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【5月19日】 How to Determine the Potential Barrier Height at the Grain Boundaries in Ion-conducting Oxides
发布时间:2015-05-17 14:11:10作者:   来源:    点击率:

     

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报告题目: How to Determine the Potential Barrier Height at the Grain Boundaries in Ion-conducting Oxides

时间与地点:2015519 上午10:00 先进制造大楼西楼A308

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, IgbUgb, characteristics of blocking grain boundaries in solid electrolytes to various oxygen-ion and proton conductors: the model precisely reproduces theIgbUgb 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 IgbUgb 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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