Room-temperature Resistivities and PTCR Properties of Er-doped (Ba,Sr,Ca)TiO3

The effects of substitution of Sr and Ca at Ba sites on the positive temperature coefficient of resistance (PTCR) characteristics of Er-doped BaTiO3 have been studied. In (Ba0.996-xSrxEr0.004)(0.997)TiO3 system, the room-temperature resistivity (rho(25)) and temperature coefficient of resistance (TCR,alpha) decreased with increasing Sr content. As the SrO content was increased, the Curie temperature shifted to lower temperatures by 2.6 degrees C/mol%. The room-temperature resistivity also decreased with increasing CaO content in (Ba0.996-yCayEr0.004)(0.997)TiO3. However, the shift in the Curie point was negligibly small with increasing CaO content. The system co-doped with 10 mol% SrO and 10 mol% CaO, (Ba0.796Sr0.10Ca0.10Er0.004)(0.997)TiO3, showed the lowest room-temperature resistivity (3.5 Omega.cm).