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High‐Temperature Thermoelectric Behaviors of Fine‐Grained Gd‐Doped CaMnO 3 Ceramics
Author(s) -
Lan Jinle,
Lin YuanHua,
Fang Hui,
Mei Ao,
Nan CeWen,
Liu Yong,
Xu Shaoliang,
Peters Matthew
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.03673.x
Subject(s) - coprecipitation , materials science , thermoelectric effect , ceramic , grain boundary , doping , electrical resistivity and conductivity , thermal conductivity , thermoelectric materials , grain size , sintering , mineralogy , analytical chemistry (journal) , microstructure , chemical engineering , composite material , thermodynamics , chemistry , optoelectronics , physics , engineering , quantum mechanics , chromatography
Gd‐doped CaMnO 3 were synthesized by two methods: a coprecipitation route and a conventional solid‐state reaction. The ceramic samples obtained by the coprecipitation method possess nanometer‐scale grains but the grain sizes by the solid‐state reaction route are several micrometers. Our results show that the electrical conductivity is slightly decreased with a decreasing grain size, which indicates that fine‐grained ceramics can maintain good electrical property. However, thermal conductivity values of the fine‐grained sample are relatively low due to the enhancement of grain boundary scattering. The highest dimensionless figure of merit ZT =0.24 has been obtained at 973 K in the air for fine‐grained Ca 0.96 Gd 0.04 MnO 3 , suggesting that they can be a promising candidate of n ‐type material for high‐temperature thermoelectric application.