Dielectric behaviour and improved anisotropy in piezoelectric properties of modified lead titanate ceramics

Polycrystalline samples of the nominal composition Pb0.76−xSmxCa0.24Ti0.98Mn0.02O3 were prepared using a solid state reaction technique. Single-phase formation was checked through X-ray diffraction. Dielectric properties were studied as a function of frequency and temperature. The transition temperature determined from dielectric constant vs. temperature plots was found to decrease with increasing Samarium substitution. Poling field was optimized to achieve maximum piezoelectric properties. Piezoelectric coefficients e.g. d33, d31, g33, g31, gh, dh, kt and kp were measured. The experimental results successfully showed that samarium substitution is helpful to obtain a much higher value of thickness electromechanical coupling coefficient, kt (∼ 57%) while maintaining a smaller planar electromechanical coupling coefficient, kp in PCT ceramics.