272227 Quantum Mechanical Study of Doping and Hydration Thermodynamics At the Surface of Yttrium-Doped Barium Cerate

Thursday, November 1, 2012: 1:10 PM
415 (Convention Center )
Tania A. Tauer and J.Will Medlin, Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO

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.

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