Sr_xPb_(1-x)TiO_3基陶瓷材料热敏特性研究

Study on the Properties of Sr_xPb_( 1-x)TiO_3-based Thermistors

以 Srx Pb1 - x Ti O3为基料 ,液相掺杂一定量的 Y和 Si,采用传统固相合成工艺方法制备出了具有明显 V型阻温特性的半导体热敏电阻 ,通过扫描电镜形貌观察、R- T特性测试及复阻抗分析表明 ,Srx Pb1 - x Ti O3陶瓷的阻温特性明显受半导化程度的影响 ,居里点以下的 NTC效应往往随着半导化程度的提高而降低。掺杂玻璃相物质Si(OC2 H5 ) 4能增强 Srx Pb1 - x Ti O3陶瓷 NTC效应 (t<TC) ,同时也造成了室温电阻率的升高 ,但掺杂 Si与出现 NTC效应并没有必然的联系。作者认为在烧结过程中由于存在 Pb挥发 ,使 Srx Pb1 - x Ti O3陶瓷材料中出现了梯度 Pb2 +离子空位及缺陷缔合是 Srx Pb1 - x Ti O3基 V型热敏陶瓷材料产生显著 NTC效应主要原因 ,同时对 Srx Pb1 - x Ti

A kind of semiconductive ceramics based on Sr xPb 1-xTiO 3 was prepared by traditional ceramics route,which exhibited distinct NTC effect below curie temperature and classical PTC effect above curie temperature.The morphology of ceramics were observed using SEM and the resistivity was measured from room temperature up to 400 °C.At the same time,the impedance spectoscopy was also used to analyze the resistance evolution of grain boundary.The results showed that the precipitating of SiO 2 on the grain boundary can increase the resistivity and improve the NTC effect,but it is not the fundamental cause of NTC effect.It is estimated that the volatilization of Pb and the different concentration of Pb 2+ from grain to grain-boundary are the radical elements resulting in the obvious NTC effect of Sr xPb 1-xTiO 3 ceramics below curie temperature.The semiconducting mechanism of Sr xPb 1-xTiO 3 ceramics is also discussed.