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1.
Hollen, Shawna M.
Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.
Degree: PhD, Physics, 2013, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:320462/ 
► The superconductor-insulator transition (SIT) is a well-known phenomenon that is observed in many types of superconducting systems, including elemental films and high Tc superconductors. Ultrathin…
(more)
▼ The superconductor-insulator
transition (SIT) is a
well-known phenomenon that is observed in many types of
superconducting systems, including elemental films and high Tc
superconductors. Ultrathin films provide a versatile platform from
which to study this ubiquitous, and possibly universal,
transition.
Two different theoretical approaches have been made to describe the
SIT in thin films. The first predicts that Cooper pairs (CPs) exist
in the insulating
phase, and the second proposes that the
transition is driven by pair-breaking, yielding an insulator of
localized single electrons.
Recent experiments showing the existence of an insulating
phase of localized CPs have provided significant support for the
first mechanism. This CP insulating (CPI)
phase exhibits dramatic
transport features including a giant magnetoresistance (MR) peak.
Previous work in the Valles lab found such a
phase in ultrathin
amorphous Bi films quench-condensed onto a substrate with a
nanohoneycomb (NHC) hole array. The local Cooper pairing
correlations of the CPI
phase were evident from Little-Parks-like
MR oscillations due to the hole array.
This thesis describes investigations of the mechanism for CP
localization and the emergence of the CPI
phase in NHC films. There
are three main results. First, the CPI
phase appears to be induced
in NHC films by the undulating surface of the substrate, which
produces regular spatial variations in thickness that give rise to
nanoscale CP islands. Second, the giant positive MR characteristic
of the CPI
phase emerges with increasing film thickness
simultaneously with the MR oscillation signal, associated with
local CP
phase coherence. The insulating phases of the thinnest
films and films in magnetic fields just beyond the MR peak likely
consist of CPs totally localized to their islands. Third, amorphous
holey films of uniform thickness do not exhibit a CPI
phase. These
films go from superconductors directly to fermionic insulators with
decreasing thickness. These results lend further insight to the
nature of the CPI
phase and also require at least two classes of
SITs: one that can describe the presence of a CPI
phase and one
that can describe a
transition from a superconductor to a fermionic
insulator.
Advisors/Committee Members: Valles, James, Jr. (Director), Mitrovic, Vesna (Reader), Feldman, Dmitri (Reader).
Subjects/Keywords: quantum phase transition
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APA (6th Edition):
Hollen, S. M. (2013). Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320462/
Chicago Manual of Style (16th Edition):
Hollen, Shawna M. “Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.” 2013. Doctoral Dissertation, Brown University. Accessed April 12, 2021.
https://repository.library.brown.edu/studio/item/bdr:320462/.
MLA Handbook (7th Edition):
Hollen, Shawna M. “Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition.” 2013. Web. 12 Apr 2021.
Vancouver:
Hollen SM. Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Apr 12].
Available from: https://repository.library.brown.edu/studio/item/bdr:320462/.
Council of Science Editors:
Hollen SM. Cooper Pair Localization in Thin Films near the
Superconductor-Insulator Transition. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320462/
Vanderbilt University
2.
Daniel, Aaron William.
Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation.
Degree: PhD, Chemistry, 2018, Vanderbilt University
URL: http://hdl.handle.net/1803/13281
► Vanadium dioxide (VO2) is a unique transition metal oxide that undergoes a first-order phase transition at 68°C from a semiconducting monoclinic phase (M) to a…
(more)
▼ Vanadium dioxide (VO2) is a unique
transition metal oxide that undergoes a first-order
phase transition at 68°C from a semiconducting monoclinic
phase (M) to a metallic rutile
phase (R). This has made VO2 of great interest in the field of condensed matter physics, but its potential applications as a chemical sensor or catalyst have been relatively ignored. VO2(M) nanoparticles were hydrothermally synthesized on a gram scale without the need for additional treatments as with other known synthesis methods. Particle films were analyzed via four-point resistivity to determine the collective
phase transition behavior. Glassy carbon electrodes were modified with VO2 particles and used to detect 2,4,6-trinitrotoluene (TNT) in solution with a limit of detection of 5 parts per billion. VO2 particles were also incorporated into carbon paste electrodes and used to reduce CO2 in a solution of sodium bicarbonate. Inclusion of VO2 shifted the onset of CO2 reduction 200 mV more positive than carbon paste alone.
Advisors/Committee Members: Richard F. Haglund, Jr. (committee member), David W. Wright (committee member), Timothy P. Hanusa (committee member), David E. Cliffel (Committee Chair).
Subjects/Keywords: Chemistry; TNT; Phase Transition; Electrochemistry
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APA (6th Edition):
Daniel, A. W. (2018). Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/13281
Chicago Manual of Style (16th Edition):
Daniel, Aaron William. “Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation.” 2018. Doctoral Dissertation, Vanderbilt University. Accessed April 12, 2021.
http://hdl.handle.net/1803/13281.
MLA Handbook (7th Edition):
Daniel, Aaron William. “Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation.” 2018. Web. 12 Apr 2021.
Vancouver:
Daniel AW. Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation. [Internet] [Doctoral dissertation]. Vanderbilt University; 2018. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1803/13281.
Council of Science Editors:
Daniel AW. Hydrothermal Synthesis of Phase-Changing Vanadium Dioxide Nanoparticles and Their Use in Environmental Remediation. [Doctoral Dissertation]. Vanderbilt University; 2018. Available from: http://hdl.handle.net/1803/13281
Louisiana State University
3.
Hu, Biao.
Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration.
Degree: PhD, Physical Sciences and Mathematics, 2011, Louisiana State University
URL: etd-07052011-144312
;
https://digitalcommons.lsu.edu/gradschool_dissertations/3909
► Correlated Electron Materials (CEMs) have attracted the attention of the materials community because the strong coupling between charge, lattice, orbital, and spin degrees of freedom…
(more)
▼ Correlated Electron Materials (CEMs) have attracted the attention of the materials community because the strong coupling between charge, lattice, orbital, and spin degrees of freedom produces exotic phenomena. Transition metal oxide series Srn+1RunO3n+1 (n = 1 to ∞) is a prototype of CEMs. The n = 2 member of this family Sr3Ru2O7 is the subject of this dissertation. It has a paramagnetic (PM) metallic ground state, which can be driven into an antiferromagnetic (AFM) insulator with a partial substitution of Ru by Mn. The focus of this research is to understand the role of chemical doping as the driving force for the structural, electrical and magnetic properties in Mn-doped Sr3Ru2O7. A key to achieving this goal is contained in the understanding of different magnetic ordering in the system. High quality single crystals Sr3(Ru1-xMnx)2O7 (0 ≤ x ≤ 0.7) have been grown by the floating zone technique in an image furnace. A phase diagram of Sr3(Ru1-xMnx)2O7 is presented, which is divided into five different regions. The structural, electrical and magnetic properties of Sr3(Ru1-xMnx)2O7 reveal a turning point around x = 0.2. Two characteristic temperatures TMIT and TM are determined from electrical and magnetic properties measurements, where TMIT represents the temperature of a metallic-to-insulating crossover while TM corresponds to a peak in magnetic susceptibility. TMIT monotonically increases with increasing x while TM shows a cusp at x = 0.16 (TMIT > TM) and the difference between TMIT and TM becomes much larger above x = 0.2. Elastic neutron scattering experiment on x = 0.16 crystal confirms a long-range AFM ordering below its TM and suggests short-range magnetic correlations between TMIT and TM.
Subjects/Keywords: Phase transition; Crystal growth
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APA (6th Edition):
Hu, B. (2011). Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-07052011-144312 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3909
Chicago Manual of Style (16th Edition):
Hu, Biao. “Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration.” 2011. Doctoral Dissertation, Louisiana State University. Accessed April 12, 2021.
etd-07052011-144312 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3909.
MLA Handbook (7th Edition):
Hu, Biao. “Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration.” 2011. Web. 12 Apr 2021.
Vancouver:
Hu B. Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration. [Internet] [Doctoral dissertation]. Louisiana State University; 2011. [cited 2021 Apr 12].
Available from: etd-07052011-144312 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3909.
Council of Science Editors:
Hu B. Evolution of structural and physical properties of transition metal oxide Sr₃(Ru₁₋xMnx)₂O₇ (0 <̲ x >̲ 0.7) with Mn concentration. [Doctoral Dissertation]. Louisiana State University; 2011. Available from: etd-07052011-144312 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3909
University of Sydney
4.
Arunasalam, Somasuntharam.
Non-perturbative phenomena and the electroweak phase transition
.
Degree: 2019, University of Sydney
URL: http://hdl.handle.net/2123/20768
► The aim of this thesis is to investigate various non-perturbative phenomena within and beyond the standard model and their implications on the electroweak phase transition.…
(more)
▼ The aim of this thesis is to investigate various non-perturbative phenomena within and beyond the standard model and their implications on the electroweak phase transition. The perturbative spectrum of the standard model is well-known and its properties have been measured to great precision. However, the same cannot be said for the non-perturbative spectrum. We first show the existence of electroweak monopoles with finite energy in a Born-Infeld extension of the standard model. We calculate this mass and discuss experimental constraints from light by light scattering and vector boson scattering processes. We also show that these monopoles are a source of B+L - and CP-violation which could potentially provide a novel method of detecting them. We then propose a new mechanism of baryogenesis through B+L - and CP-violating monopole-antimonopole annihilation processes. The phenomenon of scale invariance is an elegant solution to the hierarchy problem. We consider a model in which the standard model is a low energy effective theory with a UV completion that exhibits scale invariance. We compute the thermal effective potential for this model and show that the electroweak phase transition is dramatically different in this theory, only occurring after the QCD chiral phase transition. We also discuss phenomenological implications of this scenario. Finally, we inspect the role of gravity in quantum electrodynamics. We show that quantum gravity effects driven by electrically charged gravitational instantons give rise to a topologically non-trivial vacuum structure resulting in important phenomenological consequences like the violation of CP and the quantisation of electric charge. These models demonstrate that the detailed study of non-perturbative phenomena can yield interesting and significant results and can be the key to answering the unanswered questions in particle physics and cosmology.
Subjects/Keywords: Electroweak Phase Transition;
Baryogenesis
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APA (6th Edition):
Arunasalam, S. (2019). Non-perturbative phenomena and the electroweak phase transition
. (Thesis). University of Sydney. Retrieved from http://hdl.handle.net/2123/20768
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Arunasalam, Somasuntharam. “Non-perturbative phenomena and the electroweak phase transition
.” 2019. Thesis, University of Sydney. Accessed April 12, 2021.
http://hdl.handle.net/2123/20768.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Arunasalam, Somasuntharam. “Non-perturbative phenomena and the electroweak phase transition
.” 2019. Web. 12 Apr 2021.
Vancouver:
Arunasalam S. Non-perturbative phenomena and the electroweak phase transition
. [Internet] [Thesis]. University of Sydney; 2019. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2123/20768.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Arunasalam S. Non-perturbative phenomena and the electroweak phase transition
. [Thesis]. University of Sydney; 2019. Available from: http://hdl.handle.net/2123/20768
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Michigan
5.
Du, Xiyu.
Solid-Solid Phase Transitions in Colloidal Matter.
Degree: PhD, Physics, 2018, University of Michigan
URL: http://hdl.handle.net/2027.42/146134
► Phase transitions are ubiquitous in nature, and observed throughout everyday life from the melting of ice to the magnetization of iron. In particular, solid–solid phase…
(more)
▼ Phase transitions are ubiquitous in nature, and observed throughout everyday life from the melting of ice to the magnetization of iron. In particular, solid–solid
phase transitions are important in many areas such as metallurgy, geosciences, and the design of reconfigurable materials. Following the recent initiative of using nano building blocks to design next generation materials, we answer fundamental questions about solid–solid
phase transitions in colloidal matter and guide the design of ma- terials that can change
phase. Using the “Digital Alchemy” framework, we extend thermodynamic ensembles to include particle shape as a thermodynamic variable. This framework enables us to study the effect of altering particle shape in solid–solid
phase transitions.
We first study the thermodynamic order of two different solid–solid
phase tran- sitions (face-centered cubic (FCC)↔body-centered cubic (BCC) and BCC↔simple cubic (SC)) in hard-particle systems upon an instantaneous change in particle shape. By calculating the Landau free energy, we are able to determine the thermody- namic order of these two
phase transitions. We find FCC↔BCC is first order while BCC↔SC is second order. This work is followed up by a more detailed investigation of the FCC↔BCC
transition to explore whether it can be second order.
We next study the design of pressure-induced solid–solid
phase transitions. Here, we incorporate varying particle shape as a part of the Monte Carlo process to find the optimal shape for a given
phase transition. We successfully designed pressure driven FCC→BCC and BCC→SC transitions using three different particle shape constraints.
We also study the kinetic
transition pathway between solid phases. Our results show that there are similarities of the pathways of an entropic system and an atom- istic system. This demonstrates that we can use entropic systems as a toy model to understand better how the transformations happen in an atomistic system.
Results from this dissertation give insight into the fundamental nature of the most common, yet poorly understood
phase transitions in nature, and provide new minimal models for understanding solid–solid transitions in atomic systems. Our findings also provide guidance for the next generation of materials design.
Advisors/Committee Members: Glotzer, Sharon C (committee member), van Anders, Greg (committee member), Kotov, Nicholas (committee member), Mao, Xiaoming (committee member), Ziff, Robert M (committee member).
Subjects/Keywords: phase transition, colloidal materials, solid – solid phase transition; Physics; Science
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APA (6th Edition):
Du, X. (2018). Solid-Solid Phase Transitions in Colloidal Matter. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/146134
Chicago Manual of Style (16th Edition):
Du, Xiyu. “Solid-Solid Phase Transitions in Colloidal Matter.” 2018. Doctoral Dissertation, University of Michigan. Accessed April 12, 2021.
http://hdl.handle.net/2027.42/146134.
MLA Handbook (7th Edition):
Du, Xiyu. “Solid-Solid Phase Transitions in Colloidal Matter.” 2018. Web. 12 Apr 2021.
Vancouver:
Du X. Solid-Solid Phase Transitions in Colloidal Matter. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2027.42/146134.
Council of Science Editors:
Du X. Solid-Solid Phase Transitions in Colloidal Matter. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/146134
6.
Bruycker, Franck De.
High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération.
Degree: Docteur es, Physique, 2010, Université d'Orléans
URL: http://www.theses.fr/2010ORLE2060
► Il est important de bien connaitre le comportement des combustibles nucléaires dans des conditions extrêmes afin d’assurer la sureté des réacteurs et de prévoir les…
(more)
▼ Il est important de bien connaitre le comportement des combustibles nucléaires dans des conditions extrêmes afin d’assurer la sureté des réacteurs et de prévoir les conséquences d’un éventuel accident. L’objectif principal de cette thèse est l’étude des transitions de phase à très haute température de matériaux envisagés pour les combustibles nucléaires de quatrième génération. Dans ce but, une méthode a été développée à l’institut européen des transuraniens (ITU) pour étudier ces matériaux à des températures excédant 2500K. La technique utilisée consiste à chauffer l’échantillon à l’aide d’un laser de haute puissance et à mesurer sa température par pyrométrie. Le signal d’un second laser réfléchi par la surface de l’échantillon est aussi étudié afin de mieux caractériser les transitions de phase. Les avantages de cette technique résident dans la rapidité des expériences (de quelques dizaines de ms à quelques secondes), et dans le contrôle de l’atmosphère, ce qui permet de limiter les effets d’évaporation ou d’oxydation/réduction de l’échantillon. Il convient de signaler que seule la partie centrale de l’échantillon est fondue, la phase liquide sondée est ainsi confinée au sein de l’échantillon lui-même, ce qui évite toute interaction avec le système de fixation. Nos résultats sur les carbures d’uranium sont en accord avec ceux de la littérature, et ont permis d’affiner le calcul des diagrammes de phase pour ces matériaux stables à haute température. La technique que nous avons mise au point a été utilisée, pour la première fois, pour étudier des matériaux de haute activité. Des résultats originaux ont été obtenus sur les systèmes PuO2, NpO2, UO2-PuO2 et Pu-C.
Understanding the behaviour of nuclear materials in extreme conditions is of prime importance for the analysis of the operation limits of nuclear fuels, and prediction of possible nuclear reactor accidents, relevant to the general objectives of nuclear safety research. The main purpose of this thesis is the study of high temperature phase transitions in nuclear materials, with special attention to the candidate fuel materials for the reactors of the 4th Generation. In this framework, material properties need to be investigated at temperatures higher than 2500K, where equilibrium conditions are difficult to obtain. Laser heating combined with fast pyrometer is the method used at the European Institute for Transuranium Elements (JRC – ITU). It is associated to a novel process used to determine phase transitions, based on the detection, via a suited low-power (mW) probe laser, of changes in surface reflectivity that may accompany solid/liquid phase transitions. Fast thermal cycles, from a few ms up to the second, under almost container-free conditions and control atmosphere narrow the problem of vaporisation and sample interactions usually meet with traditional method. This new experimental approach has led to very interesting results. It confirmed earlier research for material systems known to be stable at high temperature (such as U-C) and allowed a…
Advisors/Committee Members: Malki, Mohammed (thesis director).
Subjects/Keywords: Transition de phase; Chauffage laser; Phase transition; Laser heating
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APA ·
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APA (6th Edition):
Bruycker, F. D. (2010). High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération. (Doctoral Dissertation). Université d'Orléans. Retrieved from http://www.theses.fr/2010ORLE2060
Chicago Manual of Style (16th Edition):
Bruycker, Franck De. “High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération.” 2010. Doctoral Dissertation, Université d'Orléans. Accessed April 12, 2021.
http://www.theses.fr/2010ORLE2060.
MLA Handbook (7th Edition):
Bruycker, Franck De. “High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération.” 2010. Web. 12 Apr 2021.
Vancouver:
Bruycker FD. High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération. [Internet] [Doctoral dissertation]. Université d'Orléans; 2010. [cited 2021 Apr 12].
Available from: http://www.theses.fr/2010ORLE2060.
Council of Science Editors:
Bruycker FD. High temperature phase transitions in nuclear fuels of the fourth generation. : Transitions de phases à hautes températures de combustibles nucléaires de quatrième génération. [Doctoral Dissertation]. Université d'Orléans; 2010. Available from: http://www.theses.fr/2010ORLE2060
Colorado State University
7.
Lauzier, Joshua.
Studies of tuning magnetic properties of ferromagnetic heterostructures.
Degree: PhD, Physics, 2020, Colorado State University
URL: http://hdl.handle.net/10217/208545
► The magnetic properties of hybrid systems have increasingly become an area of intense focus in both fundamental research and technological application due to the inherent…
(more)
▼ The magnetic properties of hybrid systems have increasingly become an area of intense focus in both fundamental research and technological application due to the inherent flexibility in material properties by mixing and matching various constituent components. One particularly interesting choice is hybrid heterostructures that consist of ferromagnetic (FM) materials and materials that undergo
phase transitions, coupled via structural, electronic, and/or magnetic coupling. Two canonical examples of
phase transition materials are vanadium dioxide (VO2) and iron rhodium (Fe50Rh50, abbreviated FeRh). Both materials undergo structural
phase transitions (SPT). With increasing temperature, VO2 transitions from a low temperature monoclinic to high temperature rutile structure at 340 K. The SPT is concurrent with a 4-5 orders of magnitude metal to insulator
transition (MIT) from a low temperature insulating
phase to a high temperature metallic
phase. Similarly, FeRh undergoes an isotropic 1% volume expansion at 370 K with increasing temperature. Coincident with the SPT, FeRh also undergoes a magnetic
transition from a low temperature antiferromagnetic (AF) to a high temperature ferromagnetic (FM)
phase, which is unusual for magnetic materials. The delicate nature of these transitions makes them sensitive to parameters such as stoichiometry, growth conditions, and external stimuli, which allows for high tunability of their respective
phase transitions. In this thesis, we first show in Chapter 3 that the surface morphology and MIT properties of sputtered VO2 thin films can be tuned via deposition conditions such as deposition temperature and O2 flow rate during the sputtering process while maintaining the quality of the VO2
transition. Films grown at higher temperatures (>525 ℃) and low O2 flow rate show sub 2 nm surface roughness. Higher temperatures lead to a 'melted'-like surface morphology along with a 5 orders of magnitude MIT, comparable to single crystals. Choice of substrate allows another avenue to strongly tune both the morphology and the MIT characteristics while maintaining a strong VO2
transition due to lattice mismatch. In Chapter 4, we turn to a discussion of VO2/Ni bilayer structures, where the temperature induced VO2 SPT will impart a strain across the interface into the FM layer, which will then influence the magnetic properties via magnetoelastic coupling. Due to an inverse magnetostrictive effect the coercivity and magnetization of the FM layer can be strongly modified. Tuning the VO2 SPT via growth conditions or substrate choice then allows for tuning the coupled magnetic properties of the FM. For sufficiently smooth films, there is a strong enhancement in the coercivity localized close to their respective SPT Tc due to
phase coexistence in the SPT material. This chapter is largely based on work previously published as "Coercivity enhancement in VO2/Ni bilayers due to interfacial stress" in Journal of Applied Physics.1 VO2/FM hybrid films also show a dependence on the growth conditions during the FM…
Advisors/Committee Members: de la Venta Granda, Jose (advisor), Buchanan, Kristen (committee member), Gelfand, Martin (committee member), Field, Stuart (committee member), Menoni, Carmen (committee member).
Subjects/Keywords: magnetism; phase transition; thin film; magnetostriction; hysteresis; structural phase transition
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APA (6th Edition):
Lauzier, J. (2020). Studies of tuning magnetic properties of ferromagnetic heterostructures. (Doctoral Dissertation). Colorado State University. Retrieved from http://hdl.handle.net/10217/208545
Chicago Manual of Style (16th Edition):
Lauzier, Joshua. “Studies of tuning magnetic properties of ferromagnetic heterostructures.” 2020. Doctoral Dissertation, Colorado State University. Accessed April 12, 2021.
http://hdl.handle.net/10217/208545.
MLA Handbook (7th Edition):
Lauzier, Joshua. “Studies of tuning magnetic properties of ferromagnetic heterostructures.” 2020. Web. 12 Apr 2021.
Vancouver:
Lauzier J. Studies of tuning magnetic properties of ferromagnetic heterostructures. [Internet] [Doctoral dissertation]. Colorado State University; 2020. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10217/208545.
Council of Science Editors:
Lauzier J. Studies of tuning magnetic properties of ferromagnetic heterostructures. [Doctoral Dissertation]. Colorado State University; 2020. Available from: http://hdl.handle.net/10217/208545
NSYSU
8.
Yu, Chun-cheng.
Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide.
Degree: Master, Physics, 2009, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213109-112553
► La doped HoMn2O5 in studying the influence of the local structure distortion on the magnetic transition has been investigated systematically. It is found that by…
(more)
▼ La doped HoMn2O5 in studying the influence of the local structure distortion on the magnetic
transition has been investigated systematically. It is found that by doping of La ions in a proper percentage, 0.1≤x≤0.2, the formation of the possible impurity RMnO3 (113)
phase could be suppressed; single phases of LaxHo1-xMn2O5 (0.1≤x≤0.2) can be formed in one atmosphere of flowing oxygen. For x=0.2, an weak ferromagnetic
transition on top of the paramagnetic background appears at 150K and saturated at 75K, which implies that the compound undergoes a ferromagnetic to antiferromagnetic
transition. In addition, the lattice didnât appear a huge
phase transition at low temperature, itâs observed local distortion behavior within 100~150K, and back to normal structure as high temperature ones. Itâs convinced that will be associated with the magnetic properties, which need further examination and experiment.
Advisors/Committee Members: Shih-Jye Sun (chair), Hsiung Chou (committee member), Hung-Duen Yang (chair).
Subjects/Keywords: GSAS; phase transition; Jana; Multiferroic; sol-gel
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APA (6th Edition):
Yu, C. (2009). Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213109-112553
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Yu, Chun-cheng. “Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide.” 2009. Thesis, NSYSU. Accessed April 12, 2021.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213109-112553.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Yu, Chun-cheng. “Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide.” 2009. Web. 12 Apr 2021.
Vancouver:
Yu C. Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide. [Internet] [Thesis]. NSYSU; 2009. [cited 2021 Apr 12].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213109-112553.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Yu C. Magnetic and crystal structure transition on La0.2Ho0.8Mn2O5 oxide. [Thesis]. NSYSU; 2009. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213109-112553
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
9.
吉野, 真輝; ヨシノ, マサキ.
Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols.
Degree: 博士（工学）, 2000, Gunma University / 群馬大学
URL: http://hdl.handle.net/10087/8301
学位記番号:工博乙39
Subjects/Keywords: benzenediol; phase transition
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APA (6th Edition):
吉野, 真輝; ヨシノ, . (2000). Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols. (Thesis). Gunma University / 群馬大学. Retrieved from http://hdl.handle.net/10087/8301
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
吉野, 真輝; ヨシノ, マサキ. “Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols.” 2000. Thesis, Gunma University / 群馬大学. Accessed April 12, 2021.
http://hdl.handle.net/10087/8301.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
吉野, 真輝; ヨシノ, マサキ. “Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols.” 2000. Web. 12 Apr 2021.
Vancouver:
吉野, 真輝; ヨシノ . Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols. [Internet] [Thesis]. Gunma University / 群馬大学; 2000. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10087/8301.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
吉野, 真輝; ヨシノ . Phase Transition with Volume Decrement and Its Thermodynamic Properties of Benzenediols. [Thesis]. Gunma University / 群馬大学; 2000. Available from: http://hdl.handle.net/10087/8301
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Vanderbilt University
10.
Wan, Li.
Understanding the Nanoconfined Fluid via Absolute Free Energy Determination.
Degree: PhD, Chemical Engineering, 2015, Vanderbilt University
URL: http://hdl.handle.net/1803/10898
► In recent years, the development of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) has received intense attention and effort. However, studies on nanoconfined fluid phase…
(more)
▼ In recent years, the development of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) has received intense attention and effort. However, studies on nanoconfined fluid
phase behavior has given rise to a vigorous debate that began in the early 1990s. While experiments by Klein and coworkers suggest the formation of a nanoconfinement-induced solid
phase as the separation of two solid walls is reduced below seven molecular layers, experiments by Granick and coworkers instead suggest that a glassy state is formed, since no yield stress was observed in their experiment and the measured viscosity increase is significantly smaller. Simulation studies have intrinsic molecular resolution and hence no such observational problems, but the lack of a clear demonstration that the observed solid-like structure is an equilibrated structure, has hindered wide acceptance of the results of these studies.
To determine whether a structure is metastable, the key measurement required is the free energy of the system. We concentrate our studies on development and applications of absolute free energy calculation methodology, specifically for nanoconfined systems, and uses the absolute free energy to reach a conclusive understanding of nanoconfined fluid
phase behavior. Based on free energy measurements conducted in this dissertation research, we reveal the thermodynamic role of wall-fluid interaction, wall-wall separation and fluid-wall particle size ratio, in determining nanoconfined
phase behavior.
Finally, according to investigations on the central layers of nanoconfined system with artificially increased density, we demonstrate the potential of jammed atoms in destabilizing the nanoconfinement-induced solid structure. This finding suggests one possible explanation of the divergent experimental results. In this picture, we find there are discrete solid states at separations around integer numbers of ideal layers, as opposed to a conventional fluid-solid
transition.
Advisors/Committee Members: Clare M. McCabe (committee member), M. Douglas LeVan (committee member), Terry P. Lybrand (committee member), Peter T. Cummings (Committee Chair).
Subjects/Keywords: Nanoconfined Fluid; Phase Transition; Free Energy
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APA (6th Edition):
Wan, L. (2015). Understanding the Nanoconfined Fluid via Absolute Free Energy Determination. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10898
Chicago Manual of Style (16th Edition):
Wan, Li. “Understanding the Nanoconfined Fluid via Absolute Free Energy Determination.” 2015. Doctoral Dissertation, Vanderbilt University. Accessed April 12, 2021.
http://hdl.handle.net/1803/10898.
MLA Handbook (7th Edition):
Wan, Li. “Understanding the Nanoconfined Fluid via Absolute Free Energy Determination.” 2015. Web. 12 Apr 2021.
Vancouver:
Wan L. Understanding the Nanoconfined Fluid via Absolute Free Energy Determination. [Internet] [Doctoral dissertation]. Vanderbilt University; 2015. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1803/10898.
Council of Science Editors:
Wan L. Understanding the Nanoconfined Fluid via Absolute Free Energy Determination. [Doctoral Dissertation]. Vanderbilt University; 2015. Available from: http://hdl.handle.net/1803/10898
11.
Das, Nabyendu.
Some aspects of quantum phase transition in incipient
ferroelectrics; -.
Degree: Physical Science, 2011, INFLIBNET
URL: http://shodhganga.inflibnet.ac.in/handle/10603/4723
None
Bibilography p.72-75
Advisors/Committee Members: Mishra, S G.Subjects/Keywords: quantum phase transition
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APA (6th Edition):
Das, N. (2011). Some aspects of quantum phase transition in incipient
ferroelectrics; -. (Thesis). INFLIBNET. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/4723
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Das, Nabyendu. “Some aspects of quantum phase transition in incipient
ferroelectrics; -.” 2011. Thesis, INFLIBNET. Accessed April 12, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/4723.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Das, Nabyendu. “Some aspects of quantum phase transition in incipient
ferroelectrics; -.” 2011. Web. 12 Apr 2021.
Vancouver:
Das N. Some aspects of quantum phase transition in incipient
ferroelectrics; -. [Internet] [Thesis]. INFLIBNET; 2011. [cited 2021 Apr 12].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/4723.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Das N. Some aspects of quantum phase transition in incipient
ferroelectrics; -. [Thesis]. INFLIBNET; 2011. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/4723
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Bath
12.
Thompson, Ian.
Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions.
Degree: PhD, 2015, University of Bath
URL: https://researchportal.bath.ac.uk/en/studentthesis/dynamic-phase-transitions-in-biased-ensembles-of-particle-systems-with-repulsive-interactions(eec4f877-ac19-4cee-8323-87defc8c98ab).html
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665407
► We study dynamic phase transitions in the constant-volume and constant- pressure ensembles of two different systems: a one-dimensional system of diffusive hard particles and a…
(more)
▼ We study dynamic phase transitions in the constant-volume and constant- pressure ensembles of two different systems: a one-dimensional system of diffusive hard particles and a three-dimensional glass-former of nearly-hard repulsive particles. The dynamic transitions are observed using ensembles of trajectories biased with respect to their dynamic activity, biasing to greater or lower activities than equilibrium allows us to sample different dynamic phases. We perform finite-size scaling of the transitions with respect to sys- tem size and observation time, and compare them to first-order phase tran- sitions. The two ensembles are not equivalent in the one-dimensional model. We compare our results to analytic predictions for diffusive systems in both the active and inactive phases, there are structural signatures for both dy- namic regimes. The active phases show hyperuniform ordering and the inac- tive regimes show jamming behaviour, local jamming in the constant-volume ensemble is achieved through phase separation. In the three-dimensional sys- tem we observe a dynamic transition to a glassy inactive phase, there is no obvious structural change and the structural relaxation time increases sig- nificantly. We take configurations from the active and inactive phases and subject them to a jamming protocol in order to compare the final density of the jammed packings. Previous work shows that the inactive phase of glass-forming systems have a different distribution of vibrational modes and a higher compressibility, this suggests that the jamming behaviour should differ between the two phases. We show that jammed packings generated from inactive configurations are denser than those generated from active configurations.
Subjects/Keywords: 539.7; Dynamic phase transitions; Glass transition
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Manager
APA (6th Edition):
Thompson, I. (2015). Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions. (Doctoral Dissertation). University of Bath. Retrieved from https://researchportal.bath.ac.uk/en/studentthesis/dynamic-phase-transitions-in-biased-ensembles-of-particle-systems-with-repulsive-interactions(eec4f877-ac19-4cee-8323-87defc8c98ab).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665407
Chicago Manual of Style (16th Edition):
Thompson, Ian. “Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions.” 2015. Doctoral Dissertation, University of Bath. Accessed April 12, 2021.
https://researchportal.bath.ac.uk/en/studentthesis/dynamic-phase-transitions-in-biased-ensembles-of-particle-systems-with-repulsive-interactions(eec4f877-ac19-4cee-8323-87defc8c98ab).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665407.
MLA Handbook (7th Edition):
Thompson, Ian. “Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions.” 2015. Web. 12 Apr 2021.
Vancouver:
Thompson I. Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions. [Internet] [Doctoral dissertation]. University of Bath; 2015. [cited 2021 Apr 12].
Available from: https://researchportal.bath.ac.uk/en/studentthesis/dynamic-phase-transitions-in-biased-ensembles-of-particle-systems-with-repulsive-interactions(eec4f877-ac19-4cee-8323-87defc8c98ab).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665407.
Council of Science Editors:
Thompson I. Dynamic phase transitions in biased ensembles of particle systems with repulsive interactions. [Doctoral Dissertation]. University of Bath; 2015. Available from: https://researchportal.bath.ac.uk/en/studentthesis/dynamic-phase-transitions-in-biased-ensembles-of-particle-systems-with-repulsive-interactions(eec4f877-ac19-4cee-8323-87defc8c98ab).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665407
Rice University
13.
Ji, Heng.
Hydrogen doping and the metal-insulator phase transition in vanadium dioxide.
Degree: PhD, Natural Sciences, 2015, Rice University
URL: http://hdl.handle.net/1911/88259
► Strongly correlated systems represent a major topic of study in condensed matter physics. Vanadium dioxide, a strongly correlated material, has a sharp metal-to-insulator phase transition…
(more)
▼ Strongly correlated systems represent a major topic of study in condensed matter physics. Vanadium dioxide, a strongly correlated material, has a sharp metal-to-insulator
phase transition at around 340 K (67 °C), a moderate temperature which can be easily achieved. Its potential as a functional material in optical switches and semiconductor applications has attracted a great deal of attention in recent years. In this thesis, after a detailed introduction of this material and the methods we used to grow VO2 in our lab (Chapter 1), I will discuss our attempts to modulate the electronic properties and
phase transition of single-crystal VO2 samples. It started with a plan to use ionic liquid to apply an electrostatic gate to this material. Although modulation of the resistance was observed, we also discovered an unexpected electrochemical reaction, leading to a suspicion that hydrogen doping is the reason for the change of properties of VO2 (Chapter 2). Next, a series of experiments were performed to systematically study the mechanism of this hydrogen doping process and to characterize the hydrogenated VO2. Our collaborators also provided supporting simulation results to interpret these phenomena from a theoretical point of view, as well as results from synchrotron x-ray diffraction and neutron diffraction experiments. From all these studies, we confirmed the existence of the hydrogen intercalation in VO2 (Chapter 3), and further, plotted the
phase diagram as a function of temperature and hydrogen concentration (Chapter 5). We also found that this diffusion process prefers the rutile crystal structure of VO2 (i.e. metallic
phase) and specifically, its c-axis (Chapter 4). Finally, the low-temperature electric transport properties of the hydrogenated VO2 material have been studied for the first time, and interesting magneto-resistance responses will be discussed (chapter 6).
Advisors/Committee Members: Natelson, Douglas (advisor), Du, Rui-rui (committee member), Biswal, Sibani L (committee member).
Subjects/Keywords: VO2; Vanadium dioxide; hydrogenation; phase transition
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APA (6th Edition):
Ji, H. (2015). Hydrogen doping and the metal-insulator phase transition in vanadium dioxide. (Doctoral Dissertation). Rice University. Retrieved from http://hdl.handle.net/1911/88259
Chicago Manual of Style (16th Edition):
Ji, Heng. “Hydrogen doping and the metal-insulator phase transition in vanadium dioxide.” 2015. Doctoral Dissertation, Rice University. Accessed April 12, 2021.
http://hdl.handle.net/1911/88259.
MLA Handbook (7th Edition):
Ji, Heng. “Hydrogen doping and the metal-insulator phase transition in vanadium dioxide.” 2015. Web. 12 Apr 2021.
Vancouver:
Ji H. Hydrogen doping and the metal-insulator phase transition in vanadium dioxide. [Internet] [Doctoral dissertation]. Rice University; 2015. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1911/88259.
Council of Science Editors:
Ji H. Hydrogen doping and the metal-insulator phase transition in vanadium dioxide. [Doctoral Dissertation]. Rice University; 2015. Available from: http://hdl.handle.net/1911/88259
University of Toronto
14.
Joushaghani, Arash.
Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide.
Degree: PhD, 2014, University of Toronto
URL: http://hdl.handle.net/1807/68313
► Miniaturization has the potential to reduce the size, cost, and power requirements of active optical devices. However, implementing (sub)wavelength-scale electro-optic switches with high efficiency, low…
(more)
▼ Miniaturization has the potential to reduce the size, cost, and power requirements of active optical devices. However, implementing (sub)wavelength-scale electro-optic switches with high efficiency, low insertion loss, and high extinction ratios remains challenging due to their small active volumes. Here, we use the insulator-metal
phase transition of vanadium dioxide (VO2), which exhibits a large and reversible change in the refractive index across the
phase transition to demonstrate compact, broadband, and efficient switches and photodetectors with record-setting characteristics. We begin by analyzing the electrical and optical properties of VO2 thin films across the
phase transition and discuss the fabrication processes that yield micron- and nano-scale VO2 devices. We then demonstrate a surface plasmon thermo-optic switch, which achieves an extinction ratio of 10 dB in a 5 um long device, a record for plasmonic devices. The switch operates over a 100 nm optical bandwidth, and exhibits a thermally limited switching time of 40 us. We investigate the current and voltage induced switching of VO2 in nano-gap junctions and show optical switching times as short as 20 ns. The two terminal VO2 junctions are incorporated in a silicon photonics platform to yield silicon-VO2 hybrid waveguide devices with a record extinction ratio of 12 dB in a 1 um long device. In photodetector mode, the devices exhibit a nonlinear responsivity greater than 12 A/W for optical powers less than 1 uW. This device is the smallest electrically controlled and integrated switch and photodetector capable of achieving extinction ratios > 10 dB/um. We finally investigate the ultra-fast thermal heating in gold nano-apertures and demonstrate that electron heating can change the gold lattice temperature by 300 K in tens of picoseconds. These nano-apertures can be hybridized with VO2 to demonstrate high extinction and ultrafast optical switches.
Advisors/Committee Members: Joyce, K.S. Poon, Electrical and Computer Engineering.
Subjects/Keywords: phase transition material; Vanadium dioxide; 0752
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APA (6th Edition):
Joushaghani, A. (2014). Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide. (Doctoral Dissertation). University of Toronto. Retrieved from http://hdl.handle.net/1807/68313
Chicago Manual of Style (16th Edition):
Joushaghani, Arash. “Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide.” 2014. Doctoral Dissertation, University of Toronto. Accessed April 12, 2021.
http://hdl.handle.net/1807/68313.
MLA Handbook (7th Edition):
Joushaghani, Arash. “Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide.” 2014. Web. 12 Apr 2021.
Vancouver:
Joushaghani A. Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide. [Internet] [Doctoral dissertation]. University of Toronto; 2014. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/1807/68313.
Council of Science Editors:
Joushaghani A. Micro- and Nano-scale Optoelectronic Devices Using Vanadium Dioxide. [Doctoral Dissertation]. University of Toronto; 2014. Available from: http://hdl.handle.net/1807/68313
Universitat de Valencia
15.
Martínez Martínez, Daniel.
Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
Degree: 2019, Universitat de Valencia
URL: http://hdl.handle.net/10550/68844
► Animal microbiota plays an essential role in keeping the physiological status of the host healthy. This microbiota consists of hundreds of different species that inhabit…
(more)
▼ Animal microbiota plays an essential role in keeping the physiological status of the host healthy. This microbiota consists of hundreds of different species that inhabit the host, and whose composition varies on a daily basis due to multiple factors as diets, medicine intakes, lifestyle or diseases. It is a highly dynamical system that shows variability even when the host is in a healthy condition, but visible changes happen when the system is perturbed. Thus, the main objective of this thesis aimed to study the temporal variability of human microbiota, and link it to the health status of the host. For this, we proposed a formal definition of stability in microbial systems based on the use of the Taylor#s law, an empirical law that captures the degree of variability of a community through time or space. With this tool in hand, we studied different scenarios in which the microbiome was perturbed. This law estimates the temporal variability of the microbial population and quantitatively characterises the path toward disease via a noise-induced
phase transition.
As the estimation of these systemic parameters may be of clinical utility, we applied this methodology to two cases of follow-up studies. The first one was related to the study of children suffering from acute infectious diarrhoea, one of the leading causes of mortality in children worldwide. This study aimed to correlate the dynamics of gut microbiota with the evolution of children who were suffering from acute infectious diarrhoea caused by a rotavirus. The experiment involved 10 children with acute infectious diarrhoea caused by a rotavirus and six healthy children. We observed that both alpha and beta diversities recovered with time in unhealthy children, something further supported by the analysis of their dynamics. The second case consisted of the study of the oral microbiomes from 26 volunteers during one month. We aimed to measure the correlations that could exist between microbial variability and the daily variability of five oxidative stress markers. We observed that all volunteers presented a different degree of variability, but constrained within a stable region. Furthermore, we also found that there was not a universal pattern of correlations between markers, or between OTUs and markers, pointing to a polymicrobial theory of disease.
Finally, it is known that the behaviour of a microbial ecosystem is determined by the interactions among the participating species. We present a novel methodology where the experimental design must include alterations of the microbial ecosystem to uncover specific interactions. We demonstrate that microbial interactions can be inferred from noise-induced experiments in which the variability of a given species is modified. We illustrate our findings with two examples where a four-fold increase in the variability of a given taxon uncovers some of its interactions with other taxa in the ecosystem.
Advisors/Committee Members: Moya Simarro, Andrés (advisor).
Subjects/Keywords: microbiota;
dynamics;
human health;
phase transition;
16S
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Manager
APA (6th Edition):
Martínez Martínez, D. (2019). Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
(Doctoral Dissertation). Universitat de Valencia. Retrieved from http://hdl.handle.net/10550/68844
Chicago Manual of Style (16th Edition):
Martínez Martínez, Daniel. “Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
” 2019. Doctoral Dissertation, Universitat de Valencia. Accessed April 12, 2021.
http://hdl.handle.net/10550/68844.
MLA Handbook (7th Edition):
Martínez Martínez, Daniel. “Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
” 2019. Web. 12 Apr 2021.
Vancouver:
Martínez Martínez D. Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
[Internet] [Doctoral dissertation]. Universitat de Valencia; 2019. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/10550/68844.
Council of Science Editors:
Martínez Martínez D. Stability of the human microbiome. Health and disease imprinted in the time variability of the human microbiota.
[Doctoral Dissertation]. Universitat de Valencia; 2019. Available from: http://hdl.handle.net/10550/68844
Laurentian University
16.
Dhungana, Navaraj.
Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
Degree: 2014, Laurentian University
URL: https://zone.biblio.laurentian.ca/dspace/handle/10219/2188
► The Project in Canada to Search for Supersymmetric Objects (PICASSO) searches for cold dark matter through the direct detection of Weakly Interacting Massive Particles (WIMPs)…
(more)
▼ The Project in Canada to Search for Supersymmetric Objects (PICASSO) searches for cold dark matter through the direct detection of Weakly Interacting Massive Particles (WIMPs) via spin-dependent and spin independent interactions with 19F nuclei. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. In order to reduce the background, it is essential to distinguish the signature of different background particles interacting in the detector. A dedicated setup was developed in order to study the response of the C4F10 droplets in the presence of different backgrounds.
The main objectives of this research are to identify the actual size (diameter) of the droplet increases due to phase transition and to check and establish the correlation between the droplet size and the maximum amplitude of the signal. In addition, the alpha-neutron discrimination was studied by observing each event’s image frames and the associated acoustic signal to get the amplitude distribution. The mean ratio of bubble size to droplet size was found to be 5.48, independent of temperature and type of interacting particle. Furthermore, no correlation was found between the droplet size and the maximum amplitude of the signal. As for the discrimination studies, the analysis of the signal events has confirmed that alphas generated outside the active liquid in the gel are much more difficult to discriminate from neutron than when alphas are generated inside the active liquid.
Subjects/Keywords: dark matter;
superheat;
phase transition;
amplitude
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APA (6th Edition):
Dhungana, N. (2014). Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
(Thesis). Laurentian University. Retrieved from https://zone.biblio.laurentian.ca/dspace/handle/10219/2188
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Dhungana, Navaraj. “Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
” 2014. Thesis, Laurentian University. Accessed April 12, 2021.
https://zone.biblio.laurentian.ca/dspace/handle/10219/2188.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Dhungana, Navaraj. “Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
” 2014. Web. 12 Apr 2021.
Vancouver:
Dhungana N. Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
[Internet] [Thesis]. Laurentian University; 2014. [cited 2021 Apr 12].
Available from: https://zone.biblio.laurentian.ca/dspace/handle/10219/2188.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Dhungana N. Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment.
[Thesis]. Laurentian University; 2014. Available from: https://zone.biblio.laurentian.ca/dspace/handle/10219/2188
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of North Texas
17.
Zare, Marzieh.
Cooperation-induced Criticality in Neural Networks.
Degree: 2013, University of North Texas
URL: https://digital.library.unt.edu/ark:/67531/metadc283813/
► The human brain is considered to be the most complex and powerful information-processing device in the known universe. The fundamental concepts behind the physics of…
(more)
▼ The human brain is considered to be the most complex and powerful information-processing device in the known universe. The fundamental concepts behind the physics of complex systems motivate scientists to investigate the human brain as a collective property emerging from the interaction of thousand agents. In this dissertation, I investigate the emergence of cooperation-induced properties in a system of interacting units. I demonstrate that the neural network of my research generates a series of properties such as avalanche distribution in size and duration coinciding with the experimental results on neural networks both in vivo and in vitro. Focusing attention on temporal complexity and fractal index of the system, I discuss how to define an order parameter and
phase transition. Criticality is assumed to correspond to the emergence of temporal complexity, interpreted as a manifestation of non-Poisson renewal dynamics. In addition, I study the transmission of information between two networks to confirm the criticality and discuss how the network topology changes over time in the light of Hebbian learning.
Advisors/Committee Members: Grigolini, Paolo, Krokhin, Arkadii, Gross, Guenter, Kowalski, Jacek.
Subjects/Keywords: Cooperation; criticality; temporal complexity; phase transition
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Louisiana State University
18.
Walker, Nicholas.
Identifying Structure Transitions Using Machine Learning Methods.
Degree: PhD, Condensed Matter Physics, 2020, Louisiana State University
URL: https://digitalcommons.lsu.edu/gradschool_dissertations/5311
► Methodologies from data science and machine learning, both new and old, provide an exciting opportunity to investigate physical systems using extremely expressive statistical modeling…
(more)
▼ Methodologies from data science and machine learning, both new and old, provide an exciting opportunity to investigate physical systems using extremely expressive statistical modeling techniques. Physical transitions are of particular interest, as they are accompanied by pattern changes in the configurations of the systems. Detecting and characterizing pattern changes in data happens to be a particular strength of statistical modeling in data science, especially with the highly expressive and flexible neural network models that have become increasingly computationally accessible in recent years through performance improvements in both hardware and algorithmic implementations. Conceptually, the machine learning approach can be regarded as one that employing algorithms that eschew explicit instructions in favor of strategies based around pattern extraction and inference driven by statistical analysis and large complex data sets. This allows for the investigation of physical systems using only raw configurational information to make inferences instead of relying on physical information obtained from a priori knowledge of the system. This work focuses on the extraction of useful compressed representations of physical configurations from systems of interest to automate phase classification tasks in addition to the identification of critical points and crossover regions.
Subjects/Keywords: Representation Learning; Ising Model; Melting; Phase Transition
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APA ·
Chicago ·
MLA ·
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Walker, N. (2020). Identifying Structure Transitions Using Machine Learning Methods. (Doctoral Dissertation). Louisiana State University. Retrieved from https://digitalcommons.lsu.edu/gradschool_dissertations/5311
Chicago Manual of Style (16th Edition):
Walker, Nicholas. “Identifying Structure Transitions Using Machine Learning Methods.” 2020. Doctoral Dissertation, Louisiana State University. Accessed April 12, 2021.
https://digitalcommons.lsu.edu/gradschool_dissertations/5311.
MLA Handbook (7th Edition):
Walker, Nicholas. “Identifying Structure Transitions Using Machine Learning Methods.” 2020. Web. 12 Apr 2021.
Vancouver:
Walker N. Identifying Structure Transitions Using Machine Learning Methods. [Internet] [Doctoral dissertation]. Louisiana State University; 2020. [cited 2021 Apr 12].
Available from: https://digitalcommons.lsu.edu/gradschool_dissertations/5311.
Council of Science Editors:
Walker N. Identifying Structure Transitions Using Machine Learning Methods. [Doctoral Dissertation]. Louisiana State University; 2020. Available from: https://digitalcommons.lsu.edu/gradschool_dissertations/5311
University of Minnesota
19.
Wang, Yuting.
Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions.
Degree: PhD, Physics, 2020, University of Minnesota
URL: http://hdl.handle.net/11299/215110
► The critical point of a topological phase transition is described by a conformal field theory. We first investigate the finite-size scaling away from criticality of…
(more)
▼ The critical point of a topological phase transition is described by a conformal field theory. We first investigate the finite-size scaling away from criticality of the ground state energy and find a scaling function, which discriminates between phases with different topological indexes. This function appears to be universal for all five Altland-Zirnbauer symmetry classes with non-trivial topology in one spatial dimension. We obtain an analytic form of the scaling function and compare it with numerical results. Then we verify the universality of the scaling function for the topological transition between dimerized and Haldane phases in bilinear-biquadratic spin-1 chain. To this end we perform high-accuracy variational matrix product state simulations. We show that the scaling function, expressed in terms of L/ξ, where L is the chain length and ξ is the correlation length, coincides with that of three species of non-interacting massive Majorana fermions. The latter is known to be a proper description of the conformal critical theory with central charge c=3/2. We have shown that it still holds away from the conformal point, including the finite size corrections. Finally we consider scaling of the entanglement entropy across a topological quantum phase transition for the Kitaev chain model. The change of the topology manifests itself in a sub-leading term, which scales as L-1/α with the size of the subsystem L, here α is the Rényi index. This term reveals the scaling function h_α(L/ξ), where ξ is the correlation length, which is sensitive to the topological index. The scaling function h_α(L/ξ) is independent of model parameters, suggesting some degree of its universality.
Subjects/Keywords: entanglement; finite size; quantum phase transition; topological
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APA ·
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MLA ·
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CSE |
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APA (6th Edition):
Wang, Y. (2020). Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions. (Doctoral Dissertation). University of Minnesota. Retrieved from http://hdl.handle.net/11299/215110
Chicago Manual of Style (16th Edition):
Wang, Yuting. “Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions.” 2020. Doctoral Dissertation, University of Minnesota. Accessed April 12, 2021.
http://hdl.handle.net/11299/215110.
MLA Handbook (7th Edition):
Wang, Yuting. “Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions.” 2020. Web. 12 Apr 2021.
Vancouver:
Wang Y. Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions. [Internet] [Doctoral dissertation]. University of Minnesota; 2020. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/11299/215110.
Council of Science Editors:
Wang Y. Finite Size Scaling Around One Dimensional Topological Quantum Phase Transitions. [Doctoral Dissertation]. University of Minnesota; 2020. Available from: http://hdl.handle.net/11299/215110
University of Sydney
20.
Allen, Patryck Kevyn Kidd.
Structural studies of lead-free piezoelectrics with the fresnoite structure type
.
Degree: 2012, University of Sydney
URL: http://hdl.handle.net/2123/11986
► The lead free piezoelectric fresnoite A2M3O8 (A = Ba, Sr, K, Cs; M = Ti, V, Si, Ge) modulated structure type has been investigated owing…
(more)
▼ The lead free piezoelectric fresnoite A2M3O8 (A = Ba, Sr, K, Cs; M = Ti, V, Si, Ge) modulated structure type has been investigated owing to its potential to exhibit excellent piezoelectric response coefficients. Ba2TiSi2O8, Sr2TiSi2O8, and Ba2TiGe2O8 end members in addition to members of the Ba2xSr2-2xTiSi2O8, Ba2xSr2 2xTiGe2O8, Ba2TiGe2ySi2 2yO8, and BaSrTiGe2ySi2 2yO8 series were synthesised and characterised using a combination of variable temperature diffraction techniques. The Ba2TiSi2O8 and Sr2TiSi2O8 modulated structures at ambient temperature were characterised using neutron powder diffraction for the first time. Variable temperature synchrotron X ray diffraction data showed a new means of identifying the incommensurate to prototypic structural phase transition at 433 K. Resonant ultrasound spectroscopy has shown coupling between the elastic moduli and structural changes in fresnoite samples. Polycrystalline Sr2TiSi2O8 samples were shown to undergo a first order phase transition from a two phase mixture of incommensurately modulated tetragonal and orthorhombic phases to a single incommensurately modulated orthorhombic phase that is complete by 567 K. The proportion of the orthorhombic phase Sr2TiSi2O8 samples was shown to slowly decrease on cooling to 125 K. The Sr2TiSi2O8 structure was also shown to undergo an additional phase transition from the incommensurately modulated orthorhombic phase to a tetragonal phase at 1323 K for the first time. The inclusion of barium or germanium into the Sr2TiSi2O8 structure was shown to suppress the formation of the orthorhombic phase at ambient temperature and elevated temperatures. New phase diagrams for the Ba2xSr2-2xTiSi2O8 and Sr2TiGe2ySi2 2yO8 systems summarise the phase transitions investigated. The intrinsic piezoelectric coefficients were calculated to be approximately 5 pm V 1 and 27 pm V 1 for polycrystalline samples of Ba2TiSi2O8 and Sr2TiSi2O8 respectively and compared to common piezoelectric materials.
Subjects/Keywords: Fresnoite;
Modulated structure;
Phase transition;
Incommensurate;
Piezoelectric
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Allen, P. K. K. (2012). Structural studies of lead-free piezoelectrics with the fresnoite structure type
. (Thesis). University of Sydney. Retrieved from http://hdl.handle.net/2123/11986
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Allen, Patryck Kevyn Kidd. “Structural studies of lead-free piezoelectrics with the fresnoite structure type
.” 2012. Thesis, University of Sydney. Accessed April 12, 2021.
http://hdl.handle.net/2123/11986.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Allen, Patryck Kevyn Kidd. “Structural studies of lead-free piezoelectrics with the fresnoite structure type
.” 2012. Web. 12 Apr 2021.
Vancouver:
Allen PKK. Structural studies of lead-free piezoelectrics with the fresnoite structure type
. [Internet] [Thesis]. University of Sydney; 2012. [cited 2021 Apr 12].
Available from: http://hdl.handle.net/2123/11986.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Allen PKK. Structural studies of lead-free piezoelectrics with the fresnoite structure type
. [Thesis]. University of Sydney; 2012. Available from: http://hdl.handle.net/2123/11986
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
21.
Fossati, Paul.
Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide.
Degree: Docteur es, Physique, 2012, Châtenay-Malabry, Ecole centrale de Paris
URL: http://www.theses.fr/2012ECAP0045
► Les propriétés mécaniques du combustibles nucléaire sont un problème complexe qui fait intervenir de nombreux mécanismes différents à des échelles diverses. Afin de faire progresser…
(more)
▼ Les propriétés mécaniques du combustibles nucléaire sont un problème complexe qui fait intervenir de nombreux mécanismes différents à des échelles diverses. Afin de faire progresser notre connaissance de ce matériau, nous avons effectué des simulations utilisant des modèles de Dynamique Moléculaire. Ces simulations permettent l'étude de différents mécanismes de déformation du dioxyde d'uranium à l'échelle atomique. Nous avons mis en place une procédure permettant de calculer les chemins de transition entre différents polymorphes de l'UO2 de manière statique et dynamique. Ces calculs ont confirmé la stabilité des structures fluorine à pression ambiante et cotunnite en compression, vers laquelle une transition reconstructive a été observée. Ils ont aussi montré l'importance de la direction de sollicitation principale pour déterminer la transition activée en tension, soit vers une structure scrutinyite, soit vers une structure rutile. D'autre part, les propriétés élastiques de l'UO2 ont été déterminées en température à partir d'une approche multi-modèles. L'accord relatif entre les potentiels existants pour l'UO2 a été utilisé pour déterminer des paramètres pour des modèles mésoscopiques. La propagation d’une fissure dans un monocristal a ensuite été étudié. Lors de ces simulations nous avons mis en évidence l'apparition de phases secondaires en pointe de fissure. Ce mécanisme prédit par les modèles atomistiques pourrait jouer un rôle important lors de la propagation d’une fissure aux échelles supérieures. Finalement, certaines propriétés des dislocations coin stabilisées dans le cristal UO2 ont été étudiées. La structure de cœur de ces dislocations dans différents plans de glissements a été comparée. Leur contrainte critique de glissement en fonction de la température a été calculée. Ces derniers calculs suggèrent un lien direct entre le désordre chimique observé au cœur de dislocations et leur mobilité.
Mechanical properties of nuclear fuel are a complex problem, involving many coupled mechanisms occurring at different length scales. We used Molecular Dynamics models to bring some light on some of these mechanisms at the atomic scale. We devised a procedure to calculate transition pathways between some UO2 polymorphs, and then carried out dynamics simulations of these transitions. We confirmed the stability of the cotunnite structure at high pressure using various empirical potentials, the fluorite structure being the most stable at room pressure. Moreover, we showed a reconstructive phase transition between the fluorite and cotunnite structures. We also showed the importance of the major deformation axis on the kind of transition that occur under tensile conditions. Depending on the loading direction, a scrutinyite or rutile phase can appear. We then calculated the elastic behaviour of UO2 using different potentials. The relative agreement between them was used to produce a set of parameters to be used as input in mesoscale models. We also simulated crack propagation in UO2 single crystals. These simulations…
Advisors/Committee Members: Devincre, Benoît (thesis director).
Subjects/Keywords: Dynamique moléculaire; Transition de phase; Combustible nucléaire; Molecular dynamics; Phase transition; Nuclear fuel
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Fossati, P. (2012). Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide. (Doctoral Dissertation). Châtenay-Malabry, Ecole centrale de Paris. Retrieved from http://www.theses.fr/2012ECAP0045
Chicago Manual of Style (16th Edition):
Fossati, Paul. “Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide.” 2012. Doctoral Dissertation, Châtenay-Malabry, Ecole centrale de Paris. Accessed April 12, 2021.
http://www.theses.fr/2012ECAP0045.
MLA Handbook (7th Edition):
Fossati, Paul. “Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide.” 2012. Web. 12 Apr 2021.
Vancouver:
Fossati P. Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide. [Internet] [Doctoral dissertation]. Châtenay-Malabry, Ecole centrale de Paris; 2012. [cited 2021 Apr 12].
Available from: http://www.theses.fr/2012ECAP0045.
Council of Science Editors:
Fossati P. Contribution à l'étude des propriétés mécaniques du combustible nucléaire : Modélisation atomistique de la déformation du dioxyde d'uranium : Contribution to the study of mechanical properties of nuclear fuel : atomistic modelling of the deformation of uranium dioxide. [Doctoral Dissertation]. Châtenay-Malabry, Ecole centrale de Paris; 2012. Available from: http://www.theses.fr/2012ECAP0045
22.
Lavrskyi, Mykola.
Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures.
Degree: Docteur es, Physique, 2017, Normandie
URL: http://www.theses.fr/2017NORMR003
► Cette thèse a été centrée sur l’étude de la formation d’une phase martensitique dans les aciersFe-Ni-C et sur la diffusion des atomes de carbone dans…
(more)
▼ Cette thèse a été centrée sur l’étude de la formation d’une phase martensitique dans les aciersFe-Ni-C et sur la diffusion des atomes de carbone dans cette phase à basse température. Lamodélisation à l’échelle atomique a été utilisée. Pour décrire ces phénomènes, deux approchesont été développées: un modèle discret basé sur la théorie de la fonction de densité atomique(ADF) et une approche quasiparticulaire basée sur la théorie atomique de Fratons (AFT). Dansun premier temps, pour montrer l’universalité de notre approche, nous avons appliqué l'AFTpour modéliser la cinétique d'auto-assemblage des atomes initialement désordonnés à desstructures ordonnées complexes. Cette approche a ensuite été appliquée à l'étude detransformation austénite/martensite. Il a été montré que le germe de martensite se développecomme agrégat multivariant dans la matrice austénitique. En utilisant des figures de pôles etdes diagrammes de diffraction simulés, ces variants ont été identifiés et comparés aux donnéesexpérimentales. La diffusion du carbone dans la phase de martensite a été étudiée en utilisantla théorie ADF. Deux systèmes avec différentes propriétés élastiques, Fe-C et Fe-Ni-C, ont étéconsidérés. Il a été montré qu’au cours du premier stade de vieillissement, les atomes decarbone subissent une décomposition spinodale sur les interstices octaédriques du réseautétragonal centré de martensite et forment les zones riches en carbone. Ensuite, la morphologie«tweed-like» des zones riches en carbone est développée. Les résultats des simulations sontun bon accord avec les images expérimentales obtenues par sonde atomique tomographique.La relation entre une mise en ordre de Zener et la concentration des zones riches en carbone aété discutée.
This thesis examines the formation of martensite in Fe-Ni-C steels and the diffusion of carbonatoms in this phase at low temperatures. To achieve this goal the atomistic modeling have beenused. To describe these phenomena two different approaches were developed: a discretemodel based on the Atomic Density Function (ADF) theory and the quasiparticle approachesbased on the Atomic Fraton Theory (AFT). First, the AFT was tested to model a self-assemblykinetics of initially disordered systems to three different classes of ordered one: singlecomponent crystals with fcc and diamond structures, two component crystals with zinc-blendstructure, and polymers with single-strand and double-stranded helixes structures. Then thisapproach was applied to model austenite/martensite transformation. It was shown thatmartensite nucleus grows as multivariant aggregate in austenite matrix. Using pole figures andsimulated diffraction patterns these variants were identified and compared with the experimentaldata. The carbon diffusion in martensite phase was studied using ADF theory. Two systemswith the different elastic properties corresponding to the Fe-C and Fe-Ni-C systems wereconsidered. It was shown that during a first stage of aging the carbon atoms undergo a spinodaldecomposition on the octahedral interstices of bcc…
Advisors/Committee Members: Zapolsky, Héléna (thesis director).
Subjects/Keywords: Dir. physique; Transition de phase; Transformation martensitique; Phase transition; Martensitic transformation; Solidification
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lavrskyi, M. (2017). Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures. (Doctoral Dissertation). Normandie. Retrieved from http://www.theses.fr/2017NORMR003
Chicago Manual of Style (16th Edition):
Lavrskyi, Mykola. “Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures.” 2017. Doctoral Dissertation, Normandie. Accessed April 12, 2021.
http://www.theses.fr/2017NORMR003.
MLA Handbook (7th Edition):
Lavrskyi, Mykola. “Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures.” 2017. Web. 12 Apr 2021.
Vancouver:
Lavrskyi M. Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures. [Internet] [Doctoral dissertation]. Normandie; 2017. [cited 2021 Apr 12].
Available from: http://www.theses.fr/2017NORMR003.
Council of Science Editors:
Lavrskyi M. Modélisation en fonctionnelle de la densité atomique des transformations de phases dans le système Fe-C à basse température : Functional Modification of the Atomic Density of Phase Transitions in the Fe-C System at Low Temperatures. [Doctoral Dissertation]. Normandie; 2017. Available from: http://www.theses.fr/2017NORMR003
23.
Mitra, Sunanda.
Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques.
Degree: Docteur es, Chimie, 2016, Université Paris-Saclay (ComUE)
URL: http://www.theses.fr/2016SACLS562
► Ce travail de thèse porte sur une série d’échantillons de composition nominale AgBiSe2-xSx (avec x= 0 à 2), appartenant à la famille des chalcogénures ternaires…
(more)
▼ Ce travail de thèse porte sur une série d’échantillons de composition nominale AgBiSe2-xSx (avec x= 0 à 2), appartenant à la famille des chalcogénures ternaires de type I-V-VI₂. Les analyses structurales et thermiques ont mis en évidence une solution solide complète sans gap de miscibilité, et des transitions de phase pour toutes les compositions. Nous avons pu obtenir des composés monophasés à la fois des phases hexagonale et cubique, et notre étude de DRX en température à mis en évidence une phase rhomboédrique pour certaines compositions (x=1 à 2 dans AgBiSexS2-x). Les résultats de DSC ont confirmé la présence de transitions de phase pour toutes les compositions, avec un déplacement des températures de transition en fonction de la fraction de soufre/sélénium. Notre étude de DRX sous pression de l’échantillon AgBiSe₂ a montré une transition de phase induite par la pression d’une phase hexagonale à rhomboédrique puis cubique. Suite à cette observation, l’application d’une pression chimique, par la substitution de 30% du Bi par du Sb a été utilisée avec succès pour stabiliser la phase cubique pour toutes les compositions. Le dopage par Nb des échantillons substitués par l’antimoine l’a pas eu d’influence sur la nature des phases stables à l’ambiante en comparaison aux échantillons non dopés. Nous avons ensuite étudié l’influence du dopage sur les propriétés de transport. Les valeurs négatives de S pour toutes les compositions indiquent un comportement de semi-conducteur de type n dans la gamme (50-300K). Par ailleurs, nos mesures ont montré à a fois de très faibles valeurs de κ mais aussi une décroissance de ∣S∣ et ρ avec l’augmentation de la fraction de Nb. Ces résultats devraient permettre d’optimiser le facteur de puissance pour améliorer les valeurs de ZT. Enfin, une étude en collaboration avec une équipe chinoise a permis d’obtenir une valeur de ZT de 1.3 à 890K dans un composé AgPbmSnSe₂.
Here, we report on a series of samples with nominal compositions AgBiSe2-xSx (with x= 0 to 2) belonging to the class of ternary chalcogenides of type I-V-VI₂. The structural and thermal analysis result shows a complete solid solution without miscibility gap and phase transitions for all compositions. We have succeeded in obtaining single phase compounds, of both hexagonal and cubic phase, and the high temperature XRD study showed the rhombohedral phase too for selected compositions (x=1 to 2 in AgBiSexS2-x). The DSC results confirmed the presence of the phase transitions for all compositions, with a shift of the temperature of transition as a function of the sulfur/selenium fraction. The high pressure XRD investigation of the compound AgBiSe₂ showed a pressure induced phase transition from hexagonal-to-rhombohedral-to-cubic phase. In this respect, chemical pressure with 30% Sb on the Bi site has been successfully applied to stabilize the cubic phase for all compositions. Nb doping in the Sb-substituted samples does not show any change in the phase behavior at RT in comparison with the undoped samples. The influence of…
Advisors/Committee Members: Bérardan, David (thesis director).
Subjects/Keywords: Thermoélectricité; Matériaux chalcogénures; Transition de phase; Pression chimique; Thermoelectric; Chalcogenide materials; Phase transition; Chemical pressure
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MLA ·
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Export
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APA (6th Edition):
Mitra, S. (2016). Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques. (Doctoral Dissertation). Université Paris-Saclay (ComUE). Retrieved from http://www.theses.fr/2016SACLS562
Chicago Manual of Style (16th Edition):
Mitra, Sunanda. “Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques.” 2016. Doctoral Dissertation, Université Paris-Saclay (ComUE). Accessed April 12, 2021.
http://www.theses.fr/2016SACLS562.
MLA Handbook (7th Edition):
Mitra, Sunanda. “Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques.” 2016. Web. 12 Apr 2021.
Vancouver:
Mitra S. Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques. [Internet] [Doctoral dissertation]. Université Paris-Saclay (ComUE); 2016. [cited 2021 Apr 12].
Available from: http://www.theses.fr/2016SACLS562.
Council of Science Editors:
Mitra S. Chalcogenide of type I-V-VI₂ for thermoelectric applications : Chalcogénures de type I-V-VI₂ pour applications thermoélectriques. [Doctoral Dissertation]. Université Paris-Saclay (ComUE); 2016. Available from: http://www.theses.fr/2016SACLS562
Cleveland State University
24.
WAN, JIA, HONG.
Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions.
Degree: MSin Biomedical Engineering, Washkewicz College of Engineering, 2016, Cleveland State University
URL: http://rave.ohiolink.edu/etdc/view?acc_num=csu1471923273
► Elastin-like polypeptides (ELPs) are environmentally responsive biopolymers that respond to various forms of external stimuli such as temperature, light, and pH. Several factors can influence…
(more)
▼ Elastin-like polypeptides (ELPs) are environmentally
responsive biopolymers that respond to various forms of external
stimuli such as temperature, light, and pH. Several factors can
influence the transitioning behavior of ELPs. These factors include
the amino acid composition of the ELP, the protein concentration in
solution, the salt concentration of the solution, and the polymer
chain length.Elastin-like polypeptides are soluble in water below a
critical solution temperature, however, above this temperature the
ELPs become insoluble and
phase separate. This point of temperature
triggered
phase separation is referred to as the
transition
temperature. This process is completely reversible and ELPs will
redissolve once the solution temperature is decreased below the
transition temperature.In this study, the
phase transitioning
behavior for several different concentrations of a three-armed ELP,
(GVGVP)
40-foldon, was investigated. After
expression and purification of this ELP construct, characterization
was performed starting at a highly concentrated protein solution
then diluting stepwise.
Transition temperature were determined
using UV-Visible spectrophotometry then several calculation methods
were used to analyze the
transition temperature data, resulting in
multiple potential
phase diagrams. Finally, to further investigate
the
phase transitioning behavior of ELPs microscopy was used to
observe the
phase transitioning process for several samples of
different ELP concentration.
Advisors/Committee Members: Holland, Nolan B (Advisor).
Subjects/Keywords: Biomedical Engineering; Polymers; Elastin-like polypeptides; transition temperature; phase transition behavior; phase diagram
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APA (6th Edition):
WAN, JIA, H. (2016). Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions. (Masters Thesis). Cleveland State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=csu1471923273
Chicago Manual of Style (16th Edition):
WAN, JIA, HONG. “Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions.” 2016. Masters Thesis, Cleveland State University. Accessed April 12, 2021.
http://rave.ohiolink.edu/etdc/view?acc_num=csu1471923273.
MLA Handbook (7th Edition):
WAN, JIA, HONG. “Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions.” 2016. Web. 12 Apr 2021.
Vancouver:
WAN, JIA H. Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions. [Internet] [Masters thesis]. Cleveland State University; 2016. [cited 2021 Apr 12].
Available from: http://rave.ohiolink.edu/etdc/view?acc_num=csu1471923273.
Council of Science Editors:
WAN, JIA H. Investigation into the phase separation behavior of
concentrated elastin-like polypeptide solutions. [Masters Thesis]. Cleveland State University; 2016. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=csu1471923273
NSYSU
25.
Wu, Hung-Cheng.
Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study.
Degree: Master, Physics, 2013, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803113-102053
► Transitional metal oxide nanoparticles (doping 0.5 mole %) embedded in a silica glass using the sol-gel method with different annealing temperatures. For iron-oxide nanoparticles system.…
(more)
▼ Transitional metal oxide nanoparticles (doping 0.5 mole %) embedded in a silica glass using the sol-gel method with different annealing temperatures. For iron-oxide nanoparticles system. An interesting colossal enhancement of dielectric constant is observed around room temperature with diffuse
phase transition due to the thermally activated oxygen vacancies. In addition, there is a feature observed near 65 K due to ferroelectric effect. The magnetodielectric effect observed in the glass composite is considered to be affected by magnetoresistance changes. For polarization study, we observed a
transition temperature near 65 K. It is interesting to observe multiferroic phenomena in amorphous material. The characteristics of nano-magnetic iron-oxide particles were determined respectively with various techniques, such as XRD, TEM, and XANES. For cupric-oxide nanoparticles system. There is a coexistent feature observed near 250 K from magnetic and dielectric study. From magnetodielectric study, we observed this system shows a negative magnetodielectric effect.
Advisors/Committee Members: Quark Chen (chair), Jim-Long Her (chair), Hung-Duen Yang (committee member), Jiunn-Yuan Lin (chair).
Subjects/Keywords: diffuse phase transition; magnetodielectric; dielectric; ferroelectric transition; transitional metal oxide nanoparticles
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APA (6th Edition):
Wu, H. (2013). Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803113-102053
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Wu, Hung-Cheng. “Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study.” 2013. Thesis, NSYSU. Accessed April 12, 2021.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803113-102053.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Wu, Hung-Cheng. “Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study.” 2013. Web. 12 Apr 2021.
Vancouver:
Wu H. Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study. [Internet] [Thesis]. NSYSU; 2013. [cited 2021 Apr 12].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803113-102053.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Wu H. Transitional metal oxide nanoparticle embedded in SiO2 glass matrix: magnetic and dielectric study. [Thesis]. NSYSU; 2013. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803113-102053
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
26.
Varshney, Pooja.
Phase transition studies in Zro2 doped with transition
metal oxides; -.
Degree: Chemistry, 2006, Aligarh Muslim University
URL: http://shodhganga.inflibnet.ac.in/handle/10603/53738
Abstract available newline newline
-
Advisors/Committee Members: Beg, Saba.Subjects/Keywords: Phase; Transition; Studies; Doped;
Transition
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APA (6th Edition):
Varshney, P. (2006). Phase transition studies in Zro2 doped with transition
metal oxides; -. (Thesis). Aligarh Muslim University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/53738
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Varshney, Pooja. “Phase transition studies in Zro2 doped with transition
metal oxides; -.” 2006. Thesis, Aligarh Muslim University. Accessed April 12, 2021.
http://shodhganga.inflibnet.ac.in/handle/10603/53738.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Varshney, Pooja. “Phase transition studies in Zro2 doped with transition
metal oxides; -.” 2006. Web. 12 Apr 2021.
Vancouver:
Varshney P. Phase transition studies in Zro2 doped with transition
metal oxides; -. [Internet] [Thesis]. Aligarh Muslim University; 2006. [cited 2021 Apr 12].
Available from: http://shodhganga.inflibnet.ac.in/handle/10603/53738.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Varshney P. Phase transition studies in Zro2 doped with transition
metal oxides; -. [Thesis]. Aligarh Muslim University; 2006. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/53738
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Minnesota
27.
Lin, Yen-Hsiang.
Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition.
Degree: PhD, Physics, 2011, University of Minnesota
URL: http://purl.umn.edu/115916
► A combination of thickness- and perpendicular magnetic field-tuning of SI transitions has been performed on quench-deposited homogeneous a-Bi thin films with a 14.67 Angstrom a-Sb…
(more)
▼ A combination of thickness- and perpendicular magnetic field-tuning of SI transitions has been performed on quench-deposited homogeneous a-Bi thin films with a 14.67 Angstrom a-Sb underlayer. Transport properties, including measurements of resistance and of I-V characteristics have been studied in both the insulating and superconducting regimes. In the insulating regime, the resistance exhibits an Arrhenius type of conduction and the magnetoresistance (MR) exhibits a peak in perpendicular magnetic field. Furthermore, a possible quantum phase transition is found in the insulating regime. Presumably this transition is between the Bose and Fermi insulators discussed in the literature. The I-V characteristics exhibit strong non-linearities in the insulating regime at low temperatures. These non-linear curves can be well described by a heating model involving the decoupling of the electronic and phononic degrees of freedom at low temperatures. On the conductive or superconducting side of the transition, the transport properties are found to be remarkably similar to those of an overdamped random Josephson junction array, and vortex dynamics dominates the conductive behavior in both zero and non-zero magnetic fields. These observations suggest that isolated superconducting islands or localized Cooper pairs exist in both the insulating and conductive regimes. An AFM scan of the last film in the sequence has revealed that this series of films although continuous, has thickness variations on a mesoscopic length scale. Therefore, it is not surprising that there may be superconducting islands. The AFM scan also suggests that some of the thick, nominal granular films grown by quench condensed deposition are directly connected with large thickness variations. These insulating granular films also exhibit an Arrhenius type conduction at low temperatures, which reveals the existence of a hard gap in the electronic density of states, which is consistent with the theory of Feigel'man et al.. However, the activation energy of the Arrhenius type conduction found in the thickness tuning homogeneous a-Bi films doesn't follow this model. Therefore, the model may not completely explain the hard gap.
Subjects/Keywords: Disorder superconductor; Quantum phase transition; Superconuctor-Insulator transition; Physics
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APA ·
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APA (6th Edition):
Lin, Y. (2011). Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition. (Doctoral Dissertation). University of Minnesota. Retrieved from http://purl.umn.edu/115916
Chicago Manual of Style (16th Edition):
Lin, Yen-Hsiang. “Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition.” 2011. Doctoral Dissertation, University of Minnesota. Accessed April 12, 2021.
http://purl.umn.edu/115916.
MLA Handbook (7th Edition):
Lin, Yen-Hsiang. “Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition.” 2011. Web. 12 Apr 2021.
Vancouver:
Lin Y. Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition. [Internet] [Doctoral dissertation]. University of Minnesota; 2011. [cited 2021 Apr 12].
Available from: http://purl.umn.edu/115916.
Council of Science Editors:
Lin Y. Electrical transport properties of ultrathin amorphous bismuth films near the superconductor-insulator transition. [Doctoral Dissertation]. University of Minnesota; 2011. Available from: http://purl.umn.edu/115916
Princeton University
28.
Li, Qianxiao.
Phase Transition and Free Action of Non-equilibrium Systems
.
Degree: PhD, 2016, Princeton University
URL: http://arks.princeton.edu/ark:/88435/dsp01dv13zw63x
► Extending the concept of free energy to non-equilibrium systems is a central problem in non-equilibrium statistical mechanics. In this dissertation, we discuss the issue for…
(more)
▼ Extending the concept of free energy to non-equilibrium systems is a central problem in non-equilibrium statistical mechanics. In this dissertation, we discuss the issue for two classes of non-equilibrium systems. In the first part, we focus on systems endowed with a stochastic dynamics that produces non-equilibrium steady states.We first show that a naive generalization of the free energy, based on replacing the canonical ensemble by the non-equilibrium steady state distribution, does not capture dynamical information at steady state. To resolve this, we introduce a new concept,
which we term the "free action". This can be viewed as free energy on path-space and it naturally captures macroscopic
transition rates in the thermodynamic limit. Moreover, the path-space formulation allows us to develop an efficient numerical algorithm, based on Hamiltonian Monte-Carlo and thermodynamic integration, to calculate the free action. We illustrate our framework with two examples. The first is a minimal model of a chemical reaction network exhibiting a first order
phase transition, where we use the free action to identify the
transition point and
transition mechanisms. The second example is based the Staver-Levin model of forest-savanna landscape formation. Here, we show that our path-based framework remains powerful even when direct methods becomes prohibitively inefficient.
In the second part of the thesis, we consider non-ergodic systems having deterministic evolution dynamics but random initial data. A prototypical model, which can be considered a zero-temperature Ising model, is discussed. We define and calculate exactly the free energy and the free action. Essentially, in these systems the role of the canonical ensemble is played by the ensemble of initial conditions. The usefulness of this approach is demonstrated by analyzing the laminar-turbulent
transition in 2D Poiseuille flow. By extensive numerical computations, we show the existence of a thermodynamic limit and the free energy, action and various thermodynamic relations. Moreover, we show that in the thermodynamic framework, the laminar-turbulent
transition can be regarded as a continuous
phase transition. Although the set-up of such non-ergodic models are very different from those in classical statistical
physics, one can nevertheless uncover interesting thermodynamic structures.
Advisors/Committee Members: E, Weinan (advisor).
Subjects/Keywords: Forest-savanna transition;
Free energy;
Laminar-turbulent transition;
Path sampling;
Phase transition
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Li, Q. (2016). Phase Transition and Free Action of Non-equilibrium Systems
. (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp01dv13zw63x
Chicago Manual of Style (16th Edition):
Li, Qianxiao. “Phase Transition and Free Action of Non-equilibrium Systems
.” 2016. Doctoral Dissertation, Princeton University. Accessed April 12, 2021.
http://arks.princeton.edu/ark:/88435/dsp01dv13zw63x.
MLA Handbook (7th Edition):
Li, Qianxiao. “Phase Transition and Free Action of Non-equilibrium Systems
.” 2016. Web. 12 Apr 2021.
Vancouver:
Li Q. Phase Transition and Free Action of Non-equilibrium Systems
. [Internet] [Doctoral dissertation]. Princeton University; 2016. [cited 2021 Apr 12].
Available from: http://arks.princeton.edu/ark:/88435/dsp01dv13zw63x.
Council of Science Editors:
Li Q. Phase Transition and Free Action of Non-equilibrium Systems
. [Doctoral Dissertation]. Princeton University; 2016. Available from: http://arks.princeton.edu/ark:/88435/dsp01dv13zw63x
Carnegie Mellon University
29.
Zhang, Chiqun.
Theory and Computation of Line Defect Fields in Solids and Liquid Crystals.
Degree: 2017, Carnegie Mellon University
URL: http://repository.cmu.edu/dissertations/1058
► The theory and computation of line defects are discussed in the context of both solids and liquid crystals. This dissertation includes four parts. The Generalized…
(more)
▼ The theory and computation of line defects are discussed in the context of both solids and liquid crystals. This dissertation includes four parts. The Generalized Disclination theory is discussed and applied to numerous interfacial and bulk line defect problems. An augmented Oseen-Frank energy as well as a novel 2D-model is proposed and demonstrated for disclination dynamics in liquid crystal. A model based on kinematics and thermodynamics is devised to predict tactoid dynamics during the process of the isotropic-nematic phase transition in LCLC. In the first part of the thesis, the utility of the notion of generalized disclinations in materials science is discussed within the physical context of modeling interfacial and bulk line defects. The Burgers vector of a disclination dipole in linear elasticity is derived, clearly demonstrating the equivalence of its stress field to that of an edge dislocation. An explicit formula for the displacement jump of a single localized composite defect line in terms of given g.disclination and dislocation strengths is deduced based on the Weingarten theorem for g.disclination theory at finite deformation. The Burgers vector of a g.disclination dipole at finite deformation is also derived. In the second part, a numerical method is developed to solve for the stress and distortion fields of g.disclination systems. Problems of small and finite deformation theory are considered. The fields of various line defects and grain/phase boundary problems are approximated. It is demonstrated that while the far-field topological identity of a dislocation of appropriate strength and a disclinationdipole plus a slip dislocation comprising a disconnection are the same, the latter microstructure is energetically favorable. This underscores the complementary importance of all of topology, geometry, and energetics (plus kinetics) in understanding defect mechanics. It is established that finite element approximations of fields of interfacial and bulk line defects can be achieved in a systematic and routine manner, thus contributing to the study of intricate defect microstructures in the scientific understanding and predictive design of materials. In the third part, nonsingular disclination dynamics in a uniaxial nematic liquid crystal is modeled within a mathematical framework where the kinematics is a direct extension of the classical way of identifying these line defects with singularities of a unit vector field representing the nematic director. We devise a natural augmentation of the Oseen-Frank energy to account for physical situations where infinite director gradients have zero associated energy cost, as would be necessary for modeling half-integer strength disclinations within the framework of the director theory. A novel 2D-model of disclination dynamics in nematics is proposed, which is based on the extended Oseen-Frank energy and takes into account thermodynamics and the kinematics of conservation of defect topological charge. We validate this model through computations of disclination…
Subjects/Keywords: generalized disclination; dislocation; disclination; phase boundary; nematic liquid crystal; phase transition
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APA ·
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Manager
APA (6th Edition):
Zhang, C. (2017). Theory and Computation of Line Defect Fields in Solids and Liquid Crystals. (Thesis). Carnegie Mellon University. Retrieved from http://repository.cmu.edu/dissertations/1058
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zhang, Chiqun. “Theory and Computation of Line Defect Fields in Solids and Liquid Crystals.” 2017. Thesis, Carnegie Mellon University. Accessed April 12, 2021.
http://repository.cmu.edu/dissertations/1058.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zhang, Chiqun. “Theory and Computation of Line Defect Fields in Solids and Liquid Crystals.” 2017. Web. 12 Apr 2021.
Vancouver:
Zhang C. Theory and Computation of Line Defect Fields in Solids and Liquid Crystals. [Internet] [Thesis]. Carnegie Mellon University; 2017. [cited 2021 Apr 12].
Available from: http://repository.cmu.edu/dissertations/1058.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Zhang C. Theory and Computation of Line Defect Fields in Solids and Liquid Crystals. [Thesis]. Carnegie Mellon University; 2017. Available from: http://repository.cmu.edu/dissertations/1058
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Penn State University
30.
Yu, Jiabin.
Symmetry and Topology in Quantum Matter.
Degree: 2020, Penn State University
URL: https://submit-etda.libraries.psu.edu/catalog/17871jky5062
► Quantum states of matter at zero temperature are called quantum phases, which are characterized by their symmetries and topology. If two quantum phases cannot be…
(more)
▼ Quantum states of matter at zero temperature are called quantum phases, which are characterized by their symmetries and topology. If two quantum phases cannot be related by symmetry-preserving continuous transformations, they are defined to be topologically distinct. The zero-temperature transitions among quantum phases are quantum
phase transitions. Quantum
phase transitions that happen among topologically distinct phases are called topological quantum
phase transitions. The study of topological quantum phases and topological quantum
phase transitions is a central topic in condensed matter physics.
My research on quantum phases has been focused on the theoretical study of topologically nontrivial quantum phases in the crystals governed by non-interacting Hamiltonians, including topological insulator phases, topological semimetal phases, topological superconductor phases, and so on. First, we proposed a sufficient criterion that can efficiently determine whether a three-dimensional crystal is a topological semimetal or not, based on the compatibility of different expressions for a special topological invariant, the quantized bulk average value of the effective axion field. Second, we predicted the existence of various topological insulator phases and topological semimetal phases in half-Heusler materials. Third, we proposed the magnetic-resonance-induced current as a feasible experimental probe of a special kind of topological insulators, called the axion insulators. Fourth, we proposed a new pairing mixing mechanism, the singlet-quintet mixing, for superconductors with spin-3/2 fermions, demonstrated the topological superconductor
phase induced by it, and studied various properties of it, including spin-susceptibility, upper critical field, stability against the disorder, and surface Majorana flat bands.
Besides the topological quantum phases, I have also worked on quantum
phase transitions. First, we constructed the first theoretical model for the emergent supersymmetry at a discontinuous quantum
phase transition and proposed to realize it on the surface of a topological superconductor. Second, we proposed the discontinuous change of piezoelectricity as a probe of two-dimensional topological quantum
phase transitions between insulating phases, through a systematic study of all the relevant gap closing cases. In this dissertation, I first briefly introduce the basic concepts in the field of topological quantum phases and topological quantum
phase transitions with a focus on the crystals governed by noninteracting Hamiltonians. Then, I review in detail all my first-authored research works mentioned above. My other research works are briefly mentioned.
Advisors/Committee Members: Chaoxing Liu, Dissertation Advisor/Co-Advisor, Chaoxing Liu, Committee Chair/Co-Chair, Radu Roiban, Committee Member, Marcos Antonio Rigol, Committee Member, Venkatraman Gopalan, Outside Member, Nitin Samarth, Program Head/Chair.
Subjects/Keywords: Topology; Symmetry; Quantum Phase; Quantum Phase Transition; Noninteracting Crystal
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APA ·
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APA (6th Edition):
Yu, J. (2020). Symmetry and Topology in Quantum Matter. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/17871jky5062
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Yu, Jiabin. “Symmetry and Topology in Quantum Matter.” 2020. Thesis, Penn State University. Accessed April 12, 2021.
https://submit-etda.libraries.psu.edu/catalog/17871jky5062.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Yu, Jiabin. “Symmetry and Topology in Quantum Matter.” 2020. Web. 12 Apr 2021.
Vancouver:
Yu J. Symmetry and Topology in Quantum Matter. [Internet] [Thesis]. Penn State University; 2020. [cited 2021 Apr 12].
Available from: https://submit-etda.libraries.psu.edu/catalog/17871jky5062.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Yu J. Symmetry and Topology in Quantum Matter. [Thesis]. Penn State University; 2020. Available from: https://submit-etda.libraries.psu.edu/catalog/17871jky5062
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
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. 
Open Access Theses and Dissertations