The Preparation Of (Sr, Pb) TiO₃ Nano-powders And PTC Device By Sol-Gel Process

(Sr,Pb)TiO₃ is a new pattern ferroelectric semiconducting ceramics with NTC-PTC composite effects which has been found in recent ten years. Besides the positive temperature coefficient of resistance effect above the Curie temperature, it also exhibit a strong negative temperature coefficient of resistance below the Curie temperature. The component of NTCR and PTCR was combined together to have a composite function which benefit to conquer their own deficiency , So it has received much attention due to it's value of theoretics and practicality.(Sr,Pb)TiO₃ Nano-powders and ceramics were prepared by the sol-gel process and the technics was founded. According to Orthogonal method ,the effect of three factors including ration of H₂O to Ti, proportion between H₂O and HAC and gel temperature was studied to improve the process of sol-gel. The results shows that the grain size of (Sr,Pb)TiO₃ Nano-powders prepared with optimized technological condition is about 26nm. Y, La, Zr were used as donor and Mn, Li, Cu, Zn, Co were used as acceptor, and many experiments has been done with the method of liquid doped. And the effect of temperature to (Sr,Pb)TiO₃ ceramics also be studied. The results show that the highest temperature was very important to the electrical performance of the ceramics and the samples sintered at 1150℃ show the lowest resistivitis. According to analyse and contrast the results found that the samples doped Y, La as donor and Mn, Li as acceptor were better than others due to low room-temperature resistivitis and minimal resistivitis. The lowest room-temperature resistivitis and minimal resistivitis were 103.7Ω· cm and 70.47 Ω · cm. And the results also confirm that acceptor doped can improve the V-sharp composite effects but can not reduce the sample's resistivitis. And the influence to the Curie temperature of (Sr,Pb)TiO₃ was simply study in the end.