BaTiO3-based positive temperature coefficient of resistivity ceramics with low resistivities prepared by the oxalate method

Abstract

Positive temperature coefficient of resistivity (PTCR) ceramics with low resistivities at room temperature were obtained by using oxalate-derived barium titanate powders. The average room-temperature resistivity of the PTCR ceramics was 4Ω cm, and the magnitude of their PTCR jump was around four orders with a voltage proof of more than 50 Vmm−1. These PTCR properties are significantly influenced by the calcination temperature of the starting materials and by the resultant properties of the ceramic bodies. The microstructure of such-PTCR ceramics with a low room-temperature resistivity produced in this study was found to be rather heterogeneous. Complex impedance measurements revealed that the resistivity of the present PTCR materials was determined predominantly by the grain-boundary resistance even at room temperature.