Date of Completion

8-23-2017

Embargo Period

8-23-2017

Keywords

ferroelectics, nanomaterials, simulation, thermodynamics

Major Advisor

Serge Nakhmanson

Associate Advisor

S. Pamir Alpay

Associate Advisor

Jason Hancock

Field of Study

Physics

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

In this dissertation, a mesoscale modeling approach is developed aimed at simulating the properties of dielectric nano/microstructures with coupled polar, elastic, and thermal degrees of freedom, as well as the dependence of these properties on the structure size, shape, morphology and applied conditions. The versatility of this computational method to predict functional behavior is exemplified in the following systems: (i) Semiconducting core-shell nanoparticles and the influence of their size, anisotropy, microstructure and applied pressure on their optical properties; (ii) Ferroelectric nanoparticles embedded in a dielectric medium, and the dependence on their polarization-field topology and transitions on particle shape and size, dielectric medium strength, applied electric field, as well as other factors; (iii) Artificial layered-oxide material exhibiting polar Goldstone-like (or phason) ex- citations and its electrocaloric properties that are tuneable under a wide range of applied conditions. The results of these investigations highlight the great promise of functional nano/mi- crostructures for a variety of advanced engineering applications, including electrothermal energy conversion, non-volatile multibit memories, opto and low-power electronics, as well as metamaterials by design. They also detail the utility of mesoscale "control dials," I.e., manipulation of size, shape and microstructure, for fine-tuning the useful properties and operational response of functional nano/microstructures. Finally, we demonstrate that the development of predictive-grade mesoscale-level simulation techniques that accurately un- derpin complex physical phenomena occurring at this length scale is paramount for deeper understanding of the behavior of functional dielectrics and other materials.

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