Investigation of PTCR characteristics in Sm2O3-doped BaTiO3-based chip-type ceramics prepared in a reducing atmosphere

In this paper, we investigated the influence of cooling rates on electrical properties and positive temperature coefficient of resistance (PTCR) effect of (Ba 1.22−x Sm x )TiO 3 + 0.007 mol SiO 2 (BTS) ceramics, which were fired at 1200 ∘ C for 30 min in a reducing atmosphere and then reoxidized at 700–800 ∘ C for 1 h. The results showed that the room-temperature (RT) resistivity and the resistance jump of the chip-type BTS ceramics increased with an increase in the cooling rate. Furthermore, the RT resistivity of the BTS specimens gradually decreased at first and then increased with increasing donor-doping concentration. In addition, the influence of cooling rates on the microstructure of ceramics was also investigated.