Mn_(2.1)Ni_(0.9)O_4热敏陶瓷的制备与复阻抗分析

Preparation and complex impedance analysis of Mn_(2.1)Ni_(0.9)O_4 negative temperature coefficient ceramics

采用传统固相反应法制备了Mn2．1Ni0．9O4热敏陶瓷，运用X射线衍射仪、直流阻温测试仪、交流阻抗技术对其结构和电学性能进行了测试，并对Mn2．1Ni0．9O4热敏陶瓷的微观导电机理进行了分析。结果表明：Mn2．1Ni0．9O4热敏陶瓷由立方尖晶石相和岩盐相NiO组成。其电阻主要来源于晶粒和晶界的贡献，在293～363K测试温区内，其晶粒电阻和晶界电阻都表现出明显的NTC特性，且两者导电机理均符合小极化子跳跃电导模型，晶界电阻受岩盐相NiO的影响大于晶粒电阻。

The negative temperature coefficient Mn2.1Ni0.9O4 ceramics were prepared by conventional solid-state reaction method. The structure and electrical properties of the prepared ceramics were characterized by X-ray diffraction, direct current （DC） resistance temperature measurement and alternative current （AC） impedance analysis. Furthermore, the conductive mechanism of Mn2.1Ni0.9O4 ceramics were expatiated in the microscopic respect. The results show that as-prepared Mn2.1Ni0.9O4 materials are composed of phase spine and rock salt phase （NiO）. The contribution to the conductivity of Mn2.1Ni0.9O4 ceramic is mainly due to the grain boundary and grain. Both grain and grain boundary components possess NTC characteristic in the measured temperature range of 293-363 K and their conductivity exhibit a good agreement with Nernst-Einstein equation, which indicate that both conductive mechanism of grain and grain boundary components could be explained by small polaron hopping. However, the NiO phase has a greater influence on the grain boundary conductivity than the grain.