Grain growth for CuO-BaO mixtures added BaTi1+xO3+2x ceramics

CuO-BaO mixtures (molar ratio,CuO/BaO= 1,2, 2.5) at the 1 wt% level were added to BaTi1+xO3+2x ( − 0.01 ≤ × ≤ 0.02) ceramics as a liquid phase promoter to investigate the grain growth of BaTi1+xO3+2x ceramics. Sintering in air for 2 h at 950 to 1250 °C was investigated to study the densification process, whereas sintering in air for 1 to 16 h at 1150 to 1250 °C was investigated to study the grain growth. The sintered grain morphologies (small grain growth, abnormal grain growth, and normal grain growth) of BaTi1+xO3+2x ceramics depend on theTiO2/BaO ratio, the sintering temperature and time, and theCuO/BaO ratio, slightly. The average grain size increased with the sintering time and temperature. Grain growth is discussed in terms of the kinetic growth equation:Gn − Gon = Ko t exp( −Q/RT). It was found that the preexponential, the grain growth exponents, and the activation energies of the BaTi1 + xO3 + 2x system are all dependent on theCuO/BaO ratio, the sintering temperature, and theTiO2/BaO ratio. In theBaTi1+xO3+2x/CuO-BaO system, the average n values are in the range of 4.1 to 7.6, and the activation energies are in the range of 109 ± 30 to 1007 ± 180.