Enhancement of temperature coefficient of resistivity in La_0.67Ca_0.33MnO₃ polycrystalline ceramics

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• 作者：Ji Ma ; Yunqi Cai ; Wenzhang Wang ; Qi Cui ; Mya Theingi ; Hui Zhang ; Qingming Chen
• 关键词：Sol&ndash ; gel ; Sintering time ; Electrical transport properties ; La0.67Ca0.33MnO3 ceramics
• 刊名：Ceramics International
• 出版年：April, 2014
• 年：2014
• 卷：40
• 期：3
• 页码：4963-4968
• 全文大小：1351 K

文摘

La_0.67Ca_0.33MnO₃ polycrystalline ceramics with high temperature coefficient of resistivity (TCR) have been synthesized by the sol-gel method at the sintering temperature of 1450 掳C and in a sintering time range of 2 h-24 h. The micrographs of the ceramics reveal that the grains grow up from 2 渭m to about 10 渭m with increasing the sintering time. The optimization of the sintering time is found to be a simple and effective way to largely enhance the TCR values of the ceramics. The highest metal-insulator transition temperature T_p (272.5 K) and the largest TCR (21.4%) were obtained in the ceramic sintered for 12 h. The reduction of grain boundary and resistivity contributes to the enhancement of T_p and TCR values.