Room temperature resistivities and PTCR properties of Er-doped (Ba,Sr,Ca)TiO3

Effects of substitution of Sr and Ca for Ba sites on the room temperature resistivity and positive temperature coefficient of resistance (PTCR) characteristics of Er-doped BaTiO3 have been studied. In (Ba0.996−xSrxEr0.004)0.997TiO3 system, the room temperature resistivity (ρ25) and temperature coefficient of resistance (TCR, α) decreased with increasing Sr contents. As SrO content was increased, Curie temperature shifted to lower temperatures by 2.6°C/mol%. The room temperature resistivity also decreased with increasing CaO contents in (Ba0.996−yCayEr0.004)0.997TiO3 system. However, the shift in Curie point was negligibly small with increasing CaO contents. The system co-doped with 10 mol% SrO and 10 mol% CaO, (Ba0.796Sr0.10Ca0.10Er0.004)0.997TiO3 showed the lowest room temperature resistivity (3.5Ωcm).