Different piezoelectric grain size effects in BaTiO3 ceramics

Four groups of barium titanate (BaTiO3) ceramics with high piezoelectric coefficient have been successfully fabricated from different raw materials. Their average grain size (g) dependences of the piezoelectric coefficient d33 were systematically studied. It was found that for two groups of BaTiO3 ceramics, d33 firstly increases and then decreases with the increase of g, with a maximum d33 of 449 pC/N and 501 pC/N respectively at approximately 1 µm grain size, while for the other two groups of BaTiO3 ceramics, d33 keeps increasing with the increase of g. The highest d33 of 401 pC/N and 424 pC/N were obtained when g is larger than 50 µm. The experimental results indicated that piezoelectric grain size effect in BaTiO3 ceramics may be not absolute. Possible mechanisms arising from differences in domain configuration were discussed.