Densification and micro-structure evolution of BaTiO3/ZrO2 composites

The sintering of ZrO2/BaTiO3 composites was studied by stepwise, individual and non-isothermal dilatometry methods. The composites were prepared by slurry mixing followed by drying, sieving and powder compaction by uniaxial pressing. High density sintered compacts were obtained by a variable time stepwise densification method using a starting mixture with 10 mol% zirconia. Addition of ZrO2 to BaTiO3 reduced the temperature at which sintering began and a broad range of temperature of high sintering rate was observed for the composite with 10 mol% ZrO2 in the initial mixture. The addition of ZrO2 suppressed abnormal grain growth and allowed more than 97% dense ceramics to be produced by stepwise isothermal densification in short dwell time. Kinetic parameters of sintering (exponent n, specific rate constant Kt and apparent activation energy E) were evaluated from which it can be found that the mechanism of sintering is constant in the temperature range from 1260 to 1310 °C.