Temperature behavior of dielectric and piezoelectric properties of samarium-doped lead titanate ceramics

The dielectric and electromechanical coupling properties of Sm-doped and Mn-doped PbTiO/sub 3/ ceramics were investigated from 4.2 to 300 K. The upper and lower limits of the ceramic dielectric and piezoelectric properties were calculated by averaging the single-domain constants that were determined from a phenomenological theory. Comparisons of the measured and calculated properties were then made. The measured dielectric permittivity epsilon /sup T//sub 33/ and piezoelectric strain coefficient d/sub 33/ appear to be mainly due to the averaging of the intrinsic single-domain response. The large piezoelectric and electromechanical anisotropies present in modified PbTiO/sub 3/ ceramics also appear to be an intrinsic property of the material. The piezoelectric coefficient d/sub 31/, as well as the planar coupling coefficient k/sub p/, was found to have very small values over two temperature regions, from 120 to 170 K and from 240 to 270 K.<>