Seed effect in fabrication of calcium modified lead titanate ceramics

The calcium modified lead titanate [Pb0.76Ca0.24Ti0.96W0.02Co0.02O3 + MnO 0.4 wt.% + NiO 0.3 wt.% (PCaT)] bulk ceramics were fabricated. It was found that the ceramics with pure perovskite phase could be fabricated from a sol-gel powder that was annealed before being doped. The c/a ratios of the unit cell of un-doped PCaT powder and doped PCaT ceramics were 1.056 and 1.042, which were calculated according the X-ray diffraction patterns. The maximum value of piezoelectric constant d33, thickness electromechanical coupling coefficient kt, electromechanical quality factor Q and dielectric permittivity ɛ of the ceramics are 67 pC N−1, 0.52, 470 (at thickness resonance mode) and 200, respectively. The effect of powder fabrication procedure on crystalline phase purity and the function of doping element were discussed. The cause of large piezoelectric anisotropy was also investigated.