Influence of Ca Substitution on Piezoelectric Properties of Ba 1− x Ca x TiO 3

Ca has been partially substituted for Ba in the structure of BaTiO3 to investigate the influence on its dielectric relaxation time and piezoelectric properties. Ba1−x Ca x TiO3 samples with x = 0.120, 0.140, 0.142, 0.144, 0.146, 0.148, 0.150, 0.152, and 0.160 were fabricated by the solid-state reaction method. The phase composition of the samples was identified by x-ray diffraction analysis. The impedance versus frequency characteristic in a range from 100 Hz to 2.5 MHz was measured at room temperature for all samples in both disk and cylinder shape. The results showed that Ca substitution considerably affected the piezoelectric properties of the fabricated samples. The piezoelectric properties were improved and optimized for x = 0.148, for which the relaxation time reached its minimal value. The relationship between the dielectric relaxation time and piezoelectric properties was found to be associated with structural phase competition as identified by high-resolution transmission electron microscopy analysis.