Bulk and grain boundary conductivity of Ca0.97Ti1-xFexO3-δ materials

被引:69
作者
Chinarro, E
Jurado, JR
Figueiredo, FM
Frade, JR [1 ]
机构
[1] Univ Aveiro, Ceram & Glass Engn Dept, CICECO, P-3810193 Aveiro, Portugal
[2] CSIC, Inst Ceram & Vidrio, E-28049 Madrid, Spain
[3] Univ Aberta, Sci & Technol Dept, P-1269001 Lisbon, Portugal
关键词
calcium titanate; impedance spectroscopy; grain boundaries;
D O I
10.1016/S0167-2738(03)00151-6
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
Polycrystalline Ca0.97Ti1-xFexO3-delta samples with x = 0, 0.01, 0.035, 0.07 and 0.15 were prepared by a conventional ceramic route and characterised by impedance spectroscopy at different temperatures in air. Spectra obtained for samples with low iron contents (x < 0.05) clearly show two separated bulk and grain boundary contributions, which were used to determine the corresponding conductivities. Though the bulk conductivity of those samples increases slightly with additions of Fe, the true grain boundary conductivity was found nearly independent of the content of Fe, except for effects of microstructure, such as differences in grain size. The grain boundary layer thickness was also estimated. The impedance spectra obtained for samples with Fe contents of 7% or higher show a single contribution attributed to the bulk suggesting a very low grain boundary resistance, and thus revealing a major change in grain boundary behaviour relative to samples with small Fe contents. (C) 2003 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:161 / 168
页数:8
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