A series of Mn1.5-xCo1.5NixO4 (0≤x≤1.2) negative temperature coefficient materials was synthesized by the sol-gel method. The optimal pH of reaction solutions was obtained by theoretical calculation. XRD and X-ray intensity ratios (I220/I 440) and (I440/I422) studies showed that as-sintered ceramics are single spinel structures with different cation distributions. The Ni2+ ions not only enter B-site but also occupy A-site. Electrical studies showed that with increasing Ni content, the resistivity decreased from 909.229 Ω cm to 221.873 Ω cm initially in the range of x≤0.5 and then increased to 726.933 Ω cm when x=1.2, whereas the B value decreased from 4427 K to 2134 K. In addition, different sintering temperature ceramics were investigated. A higher sintering temperature results in lower resistivity and B value at same Ni content. The Mn;bsubesubbsubesubbsubesubbsubesub material showed much improved electrical stability at 125 °C for 1000 h. The rate of change (ΔR/R) is 0.2%.
Key Lab Funct Mat & Devices Special Environm CAS, Urumqi 830011, Peoples R China;Xinjiang Tech Inst Phys & Chem CAS, Urumqi 830011, Peoples R China;Xinjiang Key Lab Elect Informat Mat & Devices, Urumqi 830011, Peoples R China;Univ Chinese Acad Sci, Beijing 100049, Peoples R China
Zhang, Huimin,Chang, Aimin,Guan, Fang,et al. The optimal synthesis condition by sol-gel method and electrical properties of Mn1.5-xCo1.5NixO4 ceramics[J]. Ceramics International,2014,40(6):7865-7872.