Abnormal grain growth of tetragonal tungsten bronze structured ferroelectric ceramics

Microstructures of tetragonal tungsten bronze-structured ferroelectric ceramics vary owing to abnormal grain growth. Control of the grain microstructure stability is a critical aspect in the electrical properties. In this study, the grain growth behavior was meticulously explored through a combination of experiments and numerical simulations. Effects of the liquid phase and initial particle-size distribution on the microstructural evolution were investigated under different grain boundary energy anisotropy conditions. The grain area and edge number were calculated to investigate the grain growth kinetics and shape variation. The results revealed that the presence of a large amount of the liquid phase contributed to rapid grain growth and a duplex structure formation. The grain-size inhomogeneity can be eliminated by using initial particles with a bimodal particle-size distribution. The grain shape was mainly determined by the degree of anisotropy of the grain boundary energy and was nearly unaffected by the process parameters. The findings of this study afford theoretical guidance for microstructure regulation and stable preparation of high-performance ferroelectric ceramics.