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 (/spl sim/490/spl deg/C) and low dielectric constant (/spl sim/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/sub 1-3x/2/Y/sub x/)(Ti/sub 0,98/Mn/sub 0,02/)O/sub 3/, 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/spl deg/C. The Y modified PT ceramics have low dielectric constant (<140), high Curie point (T/sub C/>450/spl deg/C), and large electromechanical anisotropy.