Li_2CO_3助烧钴镍共掺BaTiO_3基NTC热敏材料

Co/Ni Co-Doped BaTiO_3 Based NTC Thermistors with Li_2CO_3 as Sintering Additive

为了开发新型负温度系数(negative temperature coefficient,NTC)热敏陶瓷材料,采用湿化学法制备钴镍共掺BaTiO3(BaTi0.9-xNi0.1CoxO3-δ,x=0.05,0.08,0.10,摩尔分数)粉体,并以质量分数为0.5%的Li2CO3为助烧剂,用传统烧结工艺制备相关陶瓷。用X射线衍射和扫描电子显微镜分析陶瓷的相组成与微观结构,用电阻-温度特性测试和交流阻抗谱分析研究BaTi0.9-xNi0.1CoxO3-δ陶瓷的电学性能。结果表明:在1 373 K烧结可以获得致密性好的陶瓷样品;该材料体系具有六方系晶体结构并呈现明显的NTC效应;x=0.05、0.08、0.10样品的材料常数B分别为3 590、3 796、3 354 K。用电子跃迁机理分析材料的NTC导电特性。

In order to develop a novel negative temperature coefficient（NTC） thermistor,cobalt/nickel co-doped BaTiO3（BaTi0.9-x？ Ni0.1CoxO3-δ,x=0.05,0.08,0.10,mole fraction） powders were prepared by a wet-chemical synthesis process,and related ceramics were obtained by the conventional sintering technique using 0.5%（mass fraction） Li2CO3 as sintering additive.The X-ray diffraction and scanning electron microscopy were adopted to analyze phase composition and microstructure,respectively.The resistance-tempe-rature characteristics testing and alternating current impedance analysis were used to study electrical properties of BaTi0.9-xNi0.1？ CoxO3-δ ceramics.Results show that high density ceramics can be obtained by sintering at 1 373 K.The ceramics have a hexagonal phase and show an obvious NTC effect.Material constants B of the NTC thermistors with x=0.05,0.08,0.10 are 3 590,3 796,3 354 K,respectively.The conduction mechanism of the thermistors is discussed according to the hopping conductivity model.