Effect of TiO2 content in TiO2(Ti) powder and particle size of Ti powder on PTCR characteristic of (Ba,Sr)Ti03 vacuum-sintered compacts added with Ti02(Ti) and Ti powders

摘要

The effects of TiO2 contents (or thickness of TiO2surface layer) in TiO2(Ti) powder and the grain size of Ti powder(or interparticle spacing of Ti particles) on the PTCR characteristicof the (Ba,Sr)TiO3 compact added with TiO2(Ti) or Ti, which weresintered in vacuum at 1623K for 3.6ks, were investigated.The results obtained were as follows; (1)With increasing TiO2content of the TiO2(Ti) from 12.Smass% to 25 and 37.Smass%,the range of metallic Ti content in TiO2(Ti) needed for thedevelopment of PTCR characteristic became 1.7 times larger atmaximum. (2)For the sintered compact added with 2um Ti powder,the range of Ti content needed for the development of PTCRcharacteristic was larger than that of the compact with 18um Tipowder. (3)The above phenomena seemed to be due to thehomogenization of oxygen ion concentration in (Ba,Sr)TiO3particles which are caused by increasing thickness of TiO2 layer ordecreasing interparticle spacing of Ti particles.