Effect of yttrium substitution on the structure and piezoelectric properties of lead titanate ceramics

Lead titanate (PT) is well known as a good piezoelectric material with high Curie temperature (∼490°C) and low dielectric constant (∼200). Pure lead titanate cannot be sintered as ceramic bodies, due to its high crystalline anisotropy (c/a=1.064), but dense ceramic bodies can be obtained if small additions of other elements are used. In this regard, we investigated the effect of Y addition on the structure and piezoelectric properties of PT ceramics, with the general formula (Pb_1-3x2/Y_x)(Ti_0,98Mn_0,02)O₃, and x=0.04, 0.06, 0.08 and 0.10. Density and coupling factors were determined as a function of sintering temperatures, and doping level. Temperature dependence of the electromechanical behaviour was also investigated for temperatures as high as 500°C. The Y modified PT ceramics have low dielectric constant (<140), high Curie point (T_C>450°C), and large electromechanical anisotropy.