La_(0.6)Sr_(0.4)Co_(1-y)Fe_yO_3钙矿复合氧化物的结构与电学性能

Structure and Electrical Properties of La_0.6 Sr_0.4 Co_1-y Fe_yO_3 Perovskite-Type Oxides

采用固相反应法合成出La_(0.6)Sr_(0.4)Co_(1-y)Fe_yO_3体系复合氧化物样品,XRD分析结果证实不同Co/Fe比例的样品中均形成菱形六面体钙钛矿结构,采用固相烧结法制备出致密的La_(0.6)Sr(0.4)Co_(1-y)Fe_yO_3体系陶瓷。研究结果表明,在室温到900℃温度范围内La_(0.6)Sr_(0.4)CoO_3(y=0)的电导率随温度的增加而单调降低,其它Co/Fe比例样品的电导率随着温度的增加出现最大值,电导率达到最大值的温度随Co/Fe比例的降低而提高。在低温段,La_(0.6)Sr_(0.4)Co_(1-y)Fe_yO_3体系的导电行为符合小极子导电机制,导电活化能随Co/Fe比例的降低而增加。

La0.6Sr0.4Co1-gammaFegammaO3 system oxides were synthesized by using a solid reaction method, and the perovskite-type structure with rhombohedral symmetry was certified by XRD for the oxides with different Co/Fe ratios. The results show that the electrical conductivity of La0.6Sr0.4CoO3 (gamma=O) decreases monotonously with increasing temperature in the range from room temperature to 900degreesC, while the electrical conductivities of the samples with other compositions increase with temperature and then decrease after a maximum. The temperature corresponding to the electrical conductivity maximum shifts from 250 degreesC for La0.6Sr0.4CO0.8Fe0.2O3 (gamma=0.2) to 650 degreesC for La0.6Sr0.4FeO3 (gamma=1.0) with increasing Co/Fe ratio. It was confirmed that the hopping of small polarons is the dominating mechanism for the electrical conduction at low temperature. The activation energy of the small polarons increases from 0.033 ev with the increase of Co/Fe ratio.