THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING

GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Friday, May 12, 2017

9:00 AM

in Love 210

will be held the

DISSERTATION DEFENSE

for

Jilai Ding

“PROBING COMPLEX IONIC DYNAMICS ON THE NANOSCALE VIA ENERGY DISCOVERY PLATFORMS”

Committee Members:

Dr. Nazanin Bassiri-Gharb, Advisor, ME/MSE

Dr. Raymond R. Unocic, ME

Dr. Meilin Liu, MSE

Dr. Rosario Gerhardt, MSE

Dr. Faisal Alamgir, MSE

Abstract:

Ionic dynamics underpin the functionalities of a broad spectrum of materials and devices ranging from energy storage and conversion, to sensors and catalytic devices. Electrochemical reactivity and ionic transport in these systems is, however, a complex process, controlled by the interplay of charge injection and field-controlled and diffusion-controlled transport, which are often very sensitive to the environmental conditions, microstructures and defect structures of the material.

This research uncovers complex ionic dynamics in functional oxides via energy discovery platforms, which combine microfabricated lateral devices with in-situ characterization techniques. To be specific, the water decomposition reactivity and proton conduction mechanisms are investigated in two ionic conducting oxides: nanostructured ceria (NC) and yttrium-doped barium zirconate (Y-BZO). By utilizing characterization techniques such as time-resolved Kelvin probe force microscopy (tr-KPFM), electrochemical impedance spectroscopy (EIS) and theoretical analysis such as finite element method (FEM), the effects of external conditions such as temperature, humidity and atmosphere and internal conditions such as film crystallinity, surface roughness, dopant concentration and lattice strain on the transport mechanisms of these materials systems are identified.

The comprehensive structure-property relationship study of these materials not only showcases the feasibility of energy discovery platforms in complex ionic dynamics study on the nanoscale, but also facilitate material and device design with better performance and reliability.