材料成形与模具技术国家重点实验室
“追击材料前沿，展示名师风采”
“杰出学者讲坛”学术报告
报告题目: How to Determine the Potential Barrier Height at the Grain Boundaries in Ion-conducting Oxides
时间与地点：2015年5月19日 上午10:00 先进制造大楼西楼A308室
Prof. Sangtae Kim
Dept. of Chemical Engineering and Materials Science
University of California, Davis
Director, Nano-Electroceramics Lab
Educational Background:
B.S., 1988, Sogang University, Korea
M.S., 1990, Sogang University, Korea
Ph.D., 1999, University of Houston
Postdoctor, Max Planck Institute for Solid State Research, Germany, 2000-2004
RESEARCH INTERESTS:
n Defect Chemistry of Grain Boundaries
n Defect Chemistry of Electrolyte Thin Films
n Electrical Properties of 2D Materials
Recently a new model for ionic current across blocking grain boundaries was developed by Prof. Sangtae Kim’s research group. They demonstrate the applicability of the linear diffusion model recently proposed for the current–voltage, Igb–Ugb, characteristics of blocking grain boundaries in solid electrolytes to various oxygen-ion and proton conductors: the model precisely reproduces theIgb–Ugb characteristics of La-, Sm-, Gd-, and Y-doped ceria as well as Y-doped barium zirconate to provide accurate explanations to the “power law” behavior of the Igb–Ugb relationship, i.e. Igb ∝ Ugbn, experimentally observed. The model also predicts that the grain-boundary potential, Ψgb, in doped ceria weakly depends on temperature, if the trapped charge remains constant, and that the value of Ψgb can be determined from the value of the power n. Furthermore, the model provides a plausible explanation for the increase in the Ψgb with temperature observed for the proton conductor in which the concentration of the charge carrier decreases with temperature. Hence, it is evident that the linear diffusion model is robust and applicable to grain boundaries in a large variety of practically important solid electrolytes.
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