Effects of ceramic processing parameters on the microstructure and dielectric properties of (Ba1-xCax)(Ti0.99-y, ZryMn0.01)O3 sintered in a reducing atmosphere

The effect of A/B ratio, sintering temperature, and oxygen partial pressure on microstructure and ceramic dielectric properties of 1 mol % MnO2 doped (Ba,Ca)(Ti,Zr,)O-3 sintered in a reducing atmosphere were investigated. Microstructure is found to be closely related to processing parameters. With decreasing A/B ratio, decreasing oxygen partial pressure and increasing sintering temperature, grain growth is enhanced. Concurrent with the grain size reduction, the crystal structure transformed from tetragonal to pseudocubic at room temperature and the dielectric constant, the dissipation factor and Curie point all decreased. However, the effects of grain size give a marked discrepancy on breakdown. The effect of A/B ratio and sintering temperature both suggest that breakdown voltage is decreased with increasing grain size. However, the breakdown voltage in relation to grain size by changing the oxygen partial pressure seems to show no significant difference. (C) 2001 Kluwer Academic Publishers.