The effect of high temperature HIPing and annealing on the dielectric properties of modified lead titanate ceramics

Studies on the hot isostatic pressing (HIPing) of Sm, Mn-doped lead titanate ceramics in an argon/oxygen atmosphere have shown that the HIPed materials exhibit a substantially lower dielectric loss than conventionally sintered materials (tan /spl delta/ being reduced from approximately 0.02 to 0.01 at 1 kHz). The present work was carried out in order to identify the processing variables which are most important in effecting this reduction in loss. The materials were prepared by conventional solid state reaction and subjected to a variety of HIPing and annealing conditions. A mechanism involving the re-distribution of Mn ions among the Pb and Ti sites during HIPing is proposed to account for the observed changes in dielectric loss, which show a strong correlation with changes in the electrical conductivity.