1999 年 46 巻 4 号 p. 358-363
The effects of TiO2 contents (or thickness of TiO2 surface layer) in TiO2(Ti) powder and the grain size of Ti powder (or interparticle spacing of Ti particles) on the PTCR characteristic of the (Ba, Sr)TiO3 compact added with TiO2(Ti) or Ti, which were sintered in vacuum at 1623K for 3.6ks, were investigated.
The results obtained were as follows; (1)With increasing TiO2 content of the TiO2(Ti) from 12.5mass% to 25 and 37.5mass%, the range of metallic Ti content in TiO2(Ti) needed for the development of PTCR characteristic became 1.7 times larger at maximum. (2)For the sintered compact added with 2μm Ti powder, the range of Ti content needed for the development of PTCR characteristic was larger than that of the compact with 18μm Ti powder. (3)The above phenomena seemed to be due to the homogenization of oxygen ion concentration in (Ba, Sr)TiO3 particles which are caused by increasing thickness of TiO2 layer or decreasing interparticle spacing of Ti particles.