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 Ca 2+ and La 3+ as dopants, TiO 2 , SiO 2 and MnO as sintering aids, and various firing process. The Ca 2+ 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 µ RT 2.2 ³ cm. Based on knowledge of ionization energy and bond disassociation energy, it was cleared that Ca substitution plays an important role in lowering the µ RT value in the ceramics.

Fabrication of La3+ doped Ba1−xLaxTiO3 ceramics with improved dielectric and ferroelectric properties using a composite-hydroxide-mediated method

“…Similar results are also reported in some of the donor doped BaTiO 3 samples sintered at >1200 °C in air. 9,13,45 Since, in most of the PTCR ceramics, the GBs has higher electrical resistivity than the Gs interior. Thus, the ceramics with larger Gs size (i.e., less GBs density) should exhibit lower resistance value.…”