Growth behavior of faceted Na1/2Bi1/2TiO3-BaTiO3 grains in single and two-step sintering

The grain growth behavior in the 89Na1/2Bi1/2TiO3-11BaTiO3 system has been studied at 1100 and 1200 °C, and under two-step sintering at these two temperatures. When the powder compacts were sintered at 1100 and 1200 °C, the growth behavior was distinctively abnormal and moderately abnormal, respectively. The difference can be explained in terms of the coupling effect between the maximum driving force for the growth of the largest grain and the critical driving force for appreciable migration of the grain boundary. In two-step sintering, abnormal grain growth was suppressed in the second step at 1100 °C. This beneficial effect of two-step sintering for grain growth suppression is found to be the result of a grain size distribution right after the first sintering step narrower than that of the sample conventionally sintered at 1100 °C. These results of single and two-step sintering support the general applicability of the principle of microstructural evolution.