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 BaTiO
₃
have been studied. In (Ba
_0.996-x
Sr
_x
Er
_0.004)0.997
TiO
₃
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 (Ba
_0.996-y
CayEr
_0.004
)0.997TiO
₃
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, (Ba
_0.796
Sr
_0.10
Ca
_0.10
Er
_0.004)0.997
TiO
₃
showed the lowest room temperature resistivity (3.5Ωcm).