University of Connecticut

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PhD Dissertation Defense

Tuesday, August 8, 2017
1:00pm – 3:00pm

Storrs Campus
Physics Building, P121

John Mangeri Department of Physics, University of Connecticut

Computational Design of Multifunctional Nanodielectrics

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) Zn-ZnO and ZnO-TiO2 semiconducting core-shell nanoparticles and the influence of their size, anisotropy, microstructure and applied pressure on their optical properties;

(ii) Ferroelectric PbTiO3 and BaTiO3 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) excitations 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/microstructures 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 underpin complex physical phenomena occurring at this length scale is paramount for deeper understanding of the behavior of functional dielectrics and other related materials.

Contact:

john.mangeri@uconn.edu

Physics Department (primary), UConn Master Calendar

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