Effects of Ca substitution on room temperature resistivity of donor-doped barium titanate based PTCR ceramics

Abstract

Barium titanate based semiconducting ceramics were synthesized using Ca2+ and La3+ as dopants, TiO2, SiO2 and MnO as sintering aids, and various firing process. The Ca2+ contained ceramics without impurity phases, sintered in reducing atmosphere and subsequent annealing in air, showed both the PTCR (Positive Temperature Coefficient of Resistivity) behavior and low room temperature resistivity ρRT 2.2 ω cm. Based on knowledge of ionization energy and bond disassociation energy, it was cleared that Ca substitution plays an important role in lowering the ρRT value in the ceramics. © 2014 The Ceramic Society of Japan.