Sn-Cd-W系热敏陶瓷材料的制备及其线性化机理研究

THE PREPARATION OF Sn-Cd-W THERMALLY SENSITIVE CERAMICS AND ITS LINEARITY MECHANISM

用化学共沉淀方法制备了Sn-Cd-W系热敏陶瓷材料,XRD方法测定材料的物相是CdSnO_3-CdWO_4两相的机械混合物。在控制共沉淀材料的合适成份配比的情况下,制备出的材料的电阻率-温度曲线在—20～300℃温度区间有良好的线性。探讨了阻温特性线性化的机理。热敏材料由非导体的CdWO_4大晶粒构成“棚架”结构,晶粒较小的CdSnO_3填充在CdWO_4之间。提出了由CdsnO_3晶粒和有过剩的CdO的晶界组成三维导电链的模型。由晶粒或晶界构成导电链的线化点,线化点的阻温系数凹凸互补,使得由线化点串联而成的链是线性化导电链,导电链并联交织,构成三维导电网络。三维导电链的形成是线性化的关键。

Sn-Cd-W complex thermally sensitive ceramics were prepared by chemical co-precipitation method.The experiment result of XRD shows that the ceramics are a two-phase mixture of CdWO_4 and CdSnO_3.The resistance-temperature relationship of the ceramics was measured at a temperature range of -20～300℃. It has a good linearity characteristics of resistance-temperature relationship. The linearitymechanism was also discussed. It is the formation of a three-dimention conductivity chain in the ceramicsthat is essential to the linearity of resistance-temperature relationship.