Electrical conductivity and grain boundary composition of Gd-doped and Gd/Pr co-doped ceria

被引：96

作者：

Bowman, William J. ^{[1
]}

Zhu, Jiangtao ^{[1
]}

Sharma, Renu ^{[2
]}

Crozier, Peter A. ^{[1
]}

机构：

[1] Arizona State Univ, Sch Engn Matter Transport & Energy, Tempe, AZ 85287 USA

[2] Natl Inst Stand & Technol, Ctr Nanoscale Sci & Technol, Gaithersburg, MD 20899 USA

来源：

SOLID STATE IONICS | 2015年 / 272卷

基金：

美国国家科学基金会;

关键词：

Doped ceria; Spray drying; Impedance spectroscopy; Grain boundary; Scanning transmission electron microscopy; Electron energy-loss spectroscopy; ELECTROLYTE MATERIALS; HIGH-PURITY; CERAMICS;

D O I：

10.1016/j.ssi.2014.12.006

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

We characterize electrical conductivity, microstructure, nano-scale grain boundary structure and chemistry of ceria electrolytes with nominal compositions of Gd0.2Ce0.8O2-delta (GDC) and Gd0.11Pr0.04Ce0.85O2-delta (GPDC).The electrolytes are fabricated using mixed oxide nanopowders synthesized by spray drying. AC impedance spectroscopy was performed from 150 degrees C to 700 degrees C in air to determine grain-interior electrical conductivity. Grain-boundary conductivity was determined below 300 degrees C. The grain-interior conductivity of the GPDC was higher than that of GDC by as much as 10 times, depending on the temperature. The GPDC specific grain-boundary conductivity was measured to be approximately 100 times higher than that of GDC. Energy dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) confirmed the grain-to-grain compositional uniformity of both materials following heat treatments. Grain boundaries were free of glassy intergranular phases; dopant concentration and Ce oxidation state were found to vary significantly near grain boundaries. Boundary core composition was estimated from STEM EELS to be Gd0.62Ce0.38O2-delta, and Gd0.29Pr0.16Ce0.55O2-delta in GDC and GPDC, respectively. Pr segregation to grain boundaries in the GPDC is hypothesized to enhance conductivity by both decreasing oxygen vacancy migration energy, and inducing mixed ionic-electronic conductivity in the near-boundary region. (C) 2014 Elsevier B.V. All rights reserved.

引用

页码：9 / 17

页数：9

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