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You searched for subject:(Nanocrystals Growth Kinetics). Showing records 1 – 3 of 3 total matches.

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Indian Institute of Science

1. Viswanatha, Ranjani. Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime.

Degree: 2006, Indian Institute of Science

Properties of nanocrystals are extremely sensitive to their sizes when their sizes are smaller or of the order of the excitonic diameter due to the quantum confinement effect. The interest in this field has been concentrated basically in understanding the size-property relations of nanocrystals, for example, the pronounced variation in the bandgap of the material or the fluorescence emission properties, by tuning the sizes of the nanocrystals. Thus, the optical and electronic properties of semiconductor nanocrystals can be tailor-made to suit the needs of the specific application and hence is of immense importance. One of the major aspects necessary for the actual realization of the various applications is the ability to synthesize nanocrystals of the required size with a controlled size distribution. The growing demand to obtain such nanocrystals with the required size and controlled size distribution is met largely by the solution route synthesis of nanocrystals, that constitutes an important class of synthesis methods due to their ease of implementation and the high degree of flexibility. The main difficulty of this method is that the dependence of the average size and the size distribution of the generated particles on parameters of the reaction are not understood in detail and therefore, the optimal reaction conditions are arrived at essentially in an empirical and intuitive manner. From a fundamental point of view, understanding the growth kinetics of various nanocrystals can provide a deeper insight into the phenomena. The study of growth kinetics can be experimentally achieved by measuring the time evolution of diameter using several in-situ techniques like UV-absorption and small angle X-ray scattering. Having understood the mechanism of growth of nanocrystals, it is possible to obtain the required size of the nanocrystal using optimized synthesis conditions. The properties of these high quality nanocrystals can be further tuned by doping with a small percentage of magnetic ions. The optical and magnetic properties of these nanocrystals play an important role in the various technological applications. The first part of the thesis concentrates on the theoretical methods to study the electronic structure of semiconductor nanocrystals. The second part describes the studies performed on growth of various nanocrystal systems, both in the presence and absence of capping agents. The third part of the thesis describes the studies carried out on ZnO and doped ZnO nanocrystals, synthesized using optimal conditions that were obtained in the earlier part of the thesis. The thesis is divided into five chapters which are described below. Chapter 1 provides a brief overall perspective of various interesting properties of semiconductor nanocrystals, including various concepts relevant for the study of such systems. Chapter 2 describes experimental and theoretical methods used for the study of nanocrystals reported in this thesis. In Chapter 3 of this thesis, we report results of theoretical studies carried out on III-V… Advisors/Committee Members: Sarma, D D.

Subjects/Keywords: Semiconductors; Nanomaterials; Nanocrystals; Semiconductor Nanocrystals - Electronic Structure; Semiconductor Nanocrystals - Properties; Nanocrystals - Growth Kinetics; ZnO Nanocrystals; Nanocrystallites; Nanorods; Nanotechnology

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APA (6th Edition):

Viswanatha, R. (2006). Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime. (Thesis). Indian Institute of Science. Retrieved from http://hdl.handle.net/2005/403

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):

Viswanatha, Ranjani. “Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime.” 2006. Thesis, Indian Institute of Science. Accessed July 10, 2020. http://hdl.handle.net/2005/403.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Viswanatha, Ranjani. “Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime.” 2006. Web. 10 Jul 2020.

Vancouver:

Viswanatha R. Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime. [Internet] [Thesis]. Indian Institute of Science; 2006. [cited 2020 Jul 10]. Available from: http://hdl.handle.net/2005/403.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Viswanatha R. Growth Kinetics And Electronic Properties Of Semiconducting Nanocrystals In The Quantum Confined Regime. [Thesis]. Indian Institute of Science; 2006. Available from: http://hdl.handle.net/2005/403

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of New South Wales

2. Chen, Wu Ming. Functional nanomaterials: synthesis, growth and kinetics of nanoparticles.

Degree: Materials Science & Engineering, 2012, University of New South Wales

This thesis investigates the synthesis and growth mechanisms of nanoparticles with special reference to precious metals (e.g. silver) and Bismuth based superconducting compound with stoichiometry of Bi2Sr2Ca2Cu3Ox (referred as Bi-2223). Two representative cases were studied in this work. First, a synergetic reduction approach was used to synthesize Ag nanoparticles, in which the experimental parameters, especially temperature, were optimized for the formation and growth of silver nanoplates. The kinetic control for such particle growth was discussed. Secondly, multi-filament tape of Bi-2223 nanocrystals sheathed by Ag was manufactured at the temperature of 835-845o C, respectively. The chemical reaction kinetics suggested and developed by Kolmogorov, Johnson, Mehl and Avrami (abbreviated by KJMA) were used to investigate the crystalline evolution of Bi-2223. A few new kinetics characteristics of the Bi-2223 nanocrystals were revealed: i) activation energy E of Bi-2223 crystal cannot be regarded as a constant but as a time- and temperature-dependent function; and ii) E may be positive, zero or negative, corresponding to the kinetic process of formation, equilibrium and further decomposition, respectively. In addition, the magnetic flux pinning potential energy of Bi-2223 nanocrystals determined by measured current densities, J(T, H), was also studied. The pinning activation energies, U(T, H), were quantitatively determined and closely related to the temperature but the magnetic field. Despite many different methods used for generating such materials, whereas few reports provided detailed studies regarding kinetics growth of nanoparticles (e. g. Ag and Bi-2223 nanocrystals), and their kinetic studies could provide some quantitative information for understanding particle formation, growth, and functional control.

Subjects/Keywords: Nanoparticles; Synthesis; Growth; Kinetics; Functional nanomaterials; Bi-2223; nanocrystals

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APA (6th Edition):

Chen, W. M. (2012). Functional nanomaterials: synthesis, growth and kinetics of nanoparticles. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/52747 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11420/SOURCE01?view=true

Chicago Manual of Style (16th Edition):

Chen, Wu Ming. “Functional nanomaterials: synthesis, growth and kinetics of nanoparticles.” 2012. Doctoral Dissertation, University of New South Wales. Accessed July 10, 2020. http://handle.unsw.edu.au/1959.4/52747 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11420/SOURCE01?view=true.

MLA Handbook (7th Edition):

Chen, Wu Ming. “Functional nanomaterials: synthesis, growth and kinetics of nanoparticles.” 2012. Web. 10 Jul 2020.

Vancouver:

Chen WM. Functional nanomaterials: synthesis, growth and kinetics of nanoparticles. [Internet] [Doctoral dissertation]. University of New South Wales; 2012. [cited 2020 Jul 10]. Available from: http://handle.unsw.edu.au/1959.4/52747 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11420/SOURCE01?view=true.

Council of Science Editors:

Chen WM. Functional nanomaterials: synthesis, growth and kinetics of nanoparticles. [Doctoral Dissertation]. University of New South Wales; 2012. Available from: http://handle.unsw.edu.au/1959.4/52747 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:11420/SOURCE01?view=true


Iowa State University

3. Yuan, Bin. Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals.

Degree: 2019, Iowa State University

Colloidal nanoparticles’ practical applications (e.g. photovoltaics, catalysis, bio-imaging, sensing, display, and drug delivery) rely substantially on their production. Although significant effort has been devoted to developing synthetic methods in the past few decades, majority of them were developed through time-consuming labor-intensive trial and error, and currently large scale synthesis of high quality (e.g. monodisperse) stable colloidal nanoparticles in a cheap way is very challenging. We believe a better understanding of the growth mechanisms of colloidal nanoparticles would help solve the problem. Recently, non-classical growth pathways (e.g. oriented attachment, step-growth crystallization, and formation of mesocrystals) have been recognized as important mechanisms of crystal growth. Since the pioneering work of Penn and Banfield on oriented attachment, significant progress has been made on the syntheses of new nanostructures (e.g. ultrathin nanowires, nanorods, nanorings, nanosheets) by non-classical growth mechanisms and on understanding and visualizing these processes. However these processes are still poorly understood, especially their kinetics. This work attempts to unravel key parameters that affect the kinetics of aggregative growth of ligand capped colloidal nanocrystals. A model reaction system, in which the colloidal nanocrystals grow by aggregation and the growth by other pathways (e.g. classical growth under supersaturation and Ostwald ripening) is negligible, is needed for the study but was not available. So, we had to first develop a unique sulfur precursor (i.e. oleylammonium hydrosulfide (OLAHS)) that allows us to establish the model reaction system. Its most important trait is that it quickly reacts with lead chloride producing lead sulfide nanoparticles, and the subsequent growth of the nanoparticles by classical growth mechanism under superaturation is finished within a minute. In the meantime, we found that OLAHS can provide a simple solution to a complex and long-standing problem, i.e. sustainable scalable synthesis of metal sulfide nanocrystals at low cost. The synthesis using OLAHS fulfills most of the principles of green chemistry as it (i) can give high reaction yield (e.g. over 70%), (ii) allows recycling of excess precursors, (iii) allows synthesis being conducted under ambient condition, and (iv) allows synthesis under high concentration (e.g. 90 gram of lead sulfide nanocrystals per liter of reaction volume). We collected comprehensive kinetic data (i.e. evolution of particle size, concentration, and polydispersity with time) for the growth of amine-capped lead sulfide colloidal nanoparticles through our model reaction system. Careful data analysis shows that the nanoparticles grow by coalescence (i.e., aggregation followed by reconstruction into a spherical single crystal) and the growth due to classical growth mechanism and Ostwald ripening are negligible. We developed a simple two-parameter mathematical model that fits the comprehensive data well. The model shows that the…

Subjects/Keywords: aggregative growth; colloids; kinetics; ligand capped; nanocrystals; prediction; Materials Science and Engineering; Mechanics of Materials; Nanoscience and Nanotechnology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Yuan, B. (2019). Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/17813

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):

Yuan, Bin. “Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals.” 2019. Thesis, Iowa State University. Accessed July 10, 2020. https://lib.dr.iastate.edu/etd/17813.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Yuan, Bin. “Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals.” 2019. Web. 10 Jul 2020.

Vancouver:

Yuan B. Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals. [Internet] [Thesis]. Iowa State University; 2019. [cited 2020 Jul 10]. Available from: https://lib.dr.iastate.edu/etd/17813.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Yuan B. Kinetics of the aggregative growth of ligand-capped colloidal nanocrystals. [Thesis]. Iowa State University; 2019. Available from: https://lib.dr.iastate.edu/etd/17813

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.