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You searched for subject:(Layered Materials Delamination). Showing records 1 – 2 of 2 total matches.

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Indian Institute of Science

1. Chalasani, Rajesh. Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets.

Degree: PhD, Faculty of Science, 2018, Indian Institute of Science

This thesis consists of two parts. The first part deals with the magnetic properties of Fe3O4 nanocrystals and their possible application in water remediation. The second part is on the delamination of layered materials and the preparation of new layered hybrids from the delaminated sheets. In recent years, nanoscale magnetic particles have attracted considerable attention because of their potential applications in industry, medicine and environmental remediation. The most commonly studied magnetic nanoparticles are metals, bimetals and metal oxides. Of these, magnetite, Fe3O4, nanoparticles have been the most intensively investigated as they are, non-toxic, stable and easy to synthesize. Magnetic properties of nanoparticles such as the saturation magnetization, coercivity and blocking temperature are influenced both by size and shape. Below a critical size magnetic particles can become single domain and above a critical temperature (T B , the blocking temperature) thermal fluctuations can induce random flipping of magnetic moments resulting in loss of magnetic order. At temperatures above the blocking temperature the particles are superparamagnetic. Magnetic nanocrystals of similar dimensions but with different shapes show variation in magnetic properties especially in the value of the blocking temperature, because of differences in the surface anisotropy contribution. The properties of magnetic nanoparticles are briefly reviewed in Chapter 1. The objective of the present study was to synthesize Fe3O4 nanocrystals of different morphologies, to understand the difference in magnetic properties associated with shape and to explore the possibility of using Fe3O4 nanocrystals in water remediation. In the present study, oleate capped magnetite (Fe3O4) nanocrystals of spherical and cubic morphologies of comparable dimensions (∼10nm) have been synthesized by thermal decomposition of FeOOH in high-boiling octadecene solvent (Chapter 2). The nanocrystals were characterized by XRD, TEM and XPS spectroscopy. The nanoparticles of different morphologies exhibit very different blocking temperatures. Cubic nanocrystals have a higher blocking temperature (T B = 190 K) as compared to spheres (T B = 142 K). From the shift in the hysteresis loop it is demonstrated that the higher blocking temperature is a consequence of exchange bias or exchange anisotropy that manifests when a ferromagnetic material is in physical contact with an antiferromagnetic material. In nanoparticles, the presence of an exchange bias field leads to higher blocking temperatures T B because of the magnetic exchange coupling induced at the interface between the ferromagnet and antiferromagnet. It is shown that in these iron oxide nanocrystals the exchange bias field originates from trace amounts of the antiferromagnet wustite, FeO, present along with the ferrimagnetic Fe3O4 phase. It is also shown that the higher FeO content in nanocrystals of cubic morphology is responsible for the larger exchange bias fields that in turn lead to a higher blocking temperature.… Advisors/Committee Members: Vasudevan, S (advisor).

Subjects/Keywords: Nanostructures; Iron Oxide Nanocrystals; Exfoliated Inorgnaic Nanosheets; Iron Oxide Nanocrystals; Magnetic Nanocrystals; Magnetic Nanoparticles; Magnetic Iron Oxide Nanocrystals; Magnetic Nanoparticles; Surfactant Intercalation; Layered Materials - Delamination; [email protected]; Inorganic Nanosheets; Layered Double Hydroxide; Oleate Capped Magnetite Nanocrystals; Nanotechnology

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

APA (6th Edition):

Chalasani, R. (2018). Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets. (Doctoral Dissertation). Indian Institute of Science. Retrieved from http://etd.iisc.ac.in/handle/2005/3463

Chicago Manual of Style (16th Edition):

Chalasani, Rajesh. “Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets.” 2018. Doctoral Dissertation, Indian Institute of Science. Accessed January 23, 2021. http://etd.iisc.ac.in/handle/2005/3463.

MLA Handbook (7th Edition):

Chalasani, Rajesh. “Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets.” 2018. Web. 23 Jan 2021.

Vancouver:

Chalasani R. Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets. [Internet] [Doctoral dissertation]. Indian Institute of Science; 2018. [cited 2021 Jan 23]. Available from: http://etd.iisc.ac.in/handle/2005/3463.

Council of Science Editors:

Chalasani R. Functionalized Nanostructures : Iron Oxide Nanocrystals and Exfoliated Inorganic Nanosheets. [Doctoral Dissertation]. Indian Institute of Science; 2018. Available from: http://etd.iisc.ac.in/handle/2005/3463


University of Illinois – Urbana-Champaign

2. Wang, Cai Mike. Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit.

Degree: PhD, Mechanical Engineering, 2018, University of Illinois – Urbana-Champaign

Two-dimensional (2D) layered materials, exemplified by the prototypical graphene, have been intensively studied for their diverse material properties and superlative mechanical strength. Due to their atomically-thin nature, weak basal plane van der Waals interactions, and vanishing bending stiffness, 2D materials are extremely flexible and thus susceptible to mechanical instabilities that result in deformed out-of-plane morphologies. Such unique combination of material properties and mechanical anisotropy presents new scientific and practical challenges, but also enables novel opportunities in the nanomanufacture of 2D materials and of their derivative materials systems and devices. Surface instabilities (e.g. wrinkling and buckling) and interfacial phenomena (e.g. delamination) are typically deemed as engineering nuisances and failure modes. However, these universally ubiquitous phenomena can instead be harnessed to realize novel strategies and architectures for precise manipulation and assembly of 2D and other low-dimensional nanoscale materials, the combination of which contributes to an ever-growing toolset of capabilities towards layer-by-layer nanomanufacturing at the atomically-thin limit. This dissertation details new methods that have been developed to deterministically create hierarchical and deformed 2D materials via large-scale elastic strain engineering and controlled shape memory deformation. The emergent tunable 3D architectures arising from flat 2D materials exhibit large-scale, uniform, and well-organized patterns with characteristic length scales spanning from tens of nanometers to few microns without any a priori patterning or lithographic definition of the constituent sub-nanometer 2D thin films. By controlling bulk substrate deformation, this highly robust and scalable process imparts spatially heterogeneous strain gradients that perturb the intrinsic lattice structure and consequently the local optoelectronic properties of atomically-thin monolayer graphene analogs such as semiconducting transition metal chalcogenides, thus creating highly uniform and periodic lateral superlattice configurations. In addition, the generality of this self-patterning scheme allows for facile and scalable definition of nanoscale architectures for template guided nano-convective/capillary self-assembly of arbitrary 0D/1D nanoparticles onto deformed 2D substrates. Here, high quality colloidally prepared gold nanoparticles of diverse shapes and sizes readily self-assemble into various tunable structured mixed-dimensional metamaterials, opening the opportunity to investigate emergent phenomena such as those arising from coupling between metallic plasmonic nanostructures/nanoparticles with excitons and other quasiparticles in 2D materials. Finally, with the eventual goal towards large-scale nano-manufacturing of these 2D materials and devices, a new technique has been developed to cleanly and sustainably manufacture graphene and recycle the catalyst metal substrate using benign materials. By separating the 2D… Advisors/Committee Members: Nam, SungWoo (advisor), Nam, SungWoo (Committee Chair), Saif, Taher (committee member), Murphy, Catherine J. (committee member), Lyding, Joseph W. (committee member), Mensing, Glennys A (committee member).

Subjects/Keywords: 0D/1D materials; 2D materials; 2.5D; 3D; adaptive materials; atomic force microscopy; atomically thin; AuNPs; buckling; carbon dioxide; chemical vapour deposition; CO2; conformable materials; copper; crumpling; deformation; delamination; dichroism; electrochemistry; electrolyte; excitonics; field-effect transistor; flexible electronics; gold nanoparticles; graphene; grating; green chemistry; green manufacturing; heterostructures; interfaces; layered materials; lithography-free; low-dimensional materials; materials processing; mechanical instabilities; metamaterials; molybdenum disulphide; MoS2; nano-manufacturing; nanomaterials; nanoparticles; nanoscale patterning; nano-templating; photoluminescence; plasmonics; Raman spectroscopy; self-assembly; semiconductors; strain; surface instabilities; surface wrinkling; sustainable manufacturing; three-dimensional; transition metal chalcogenide; two-dimensional materials; van der Waals materials

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

APA (6th Edition):

Wang, C. M. (2018). Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/101761

Chicago Manual of Style (16th Edition):

Wang, Cai Mike. “Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit.” 2018. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed January 23, 2021. http://hdl.handle.net/2142/101761.

MLA Handbook (7th Edition):

Wang, Cai Mike. “Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit.” 2018. Web. 23 Jan 2021.

Vancouver:

Wang CM. Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2018. [cited 2021 Jan 23]. Available from: http://hdl.handle.net/2142/101761.

Council of Science Editors:

Wang CM. Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2018. Available from: http://hdl.handle.net/2142/101761

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