2018 年 126 巻 7 号 p. 536-541
BaTiO3 ceramics with grain sizes of 4.7–26.1 µm were fabricated using 100 and 300 nm BaTiO3 powders by employing a two-step sintering (TSS) or conventional one-step sintering (CS) method. Polished and cut BaTiO3 samples were annealed for the recovery and relaxation of mechanical-processing-induced surface damage and lattice strain, and the piezoelectric properties were investigated. TSS-BaTiO3 ceramics annealed at 1000°C for 1 h with a grain size of 4.9 µm exhibited an excellent piezoelectric property of d33 = 529 pC/N, while the d33 value of CS-BaTiO3 ceramics annealed at 1200°C for 8 h with a grain size of 26.1 µm was 272 pC/N. Besides the excellent piezoelectric properties of the fine-grained BaTiO3 ceramics, the performance of the coarse-grained ceramics was higher than previously reported. The observed superior piezoelectric and electromechanical properties in annealed samples despite the increase in grain size suggested that the effect of annealing was more crucial than that of grain size.