(695c) Quantum Mechanical Study of Doping and Hydration Thermodynamics At the Surface of Yttrium-Doped Barium Cerate

Acceptor-doped perovskite oxides demonstrate promising high
temperature proton conductivities, but their poor chemical stability and
inferior conduction capabilities compared to low-temperature polymers and
liquids have limited the materials' widespread implementation. While
significant advancements have been made towards overcoming these material
limitations, a greater fundamental understanding of proton behavior would lend
towards the rational design of next-generation perovskite proton conductors.

Protons are introduced into perovskite materials through a
two-step material doping and hydration process. The primary objective of this
study is to use density functional theory to explore the thermodynamics of
material doping and hydration in yttrium-doped barium cerate (BCY), a common
perovskite that demonstrates among the highest proton conductivities within its
class of materials. A series of DFT calculations was used to determine the stability
of various surface facets of barium cerate (BaCeO₃) and explain how
surface termination influences the arrangement of dopant cations and oxygen
vacancies near the surface. Systematic calculations of energy variations with
doping position were also employed toward the development of a model for oxygen
vacancy migration from the material bulk towards various surface terminations.
The positioning of oxygen vacancies at the material surface and the mobility of
oxygen vacancies in this vicinity has a significant effect on the efficiency of
material hydration and thus is an important factor to consider when designing
efficient proton conductors. Finally, we will describe the thermodynamics of
material hydration at the BCY surface and compare these properties to previous
studies done for the bulk BCY material.