Effects of Atmospheric Powder and Grain Size on Electrical Properties of Lanthanum-modified PbTiO₃ Ceramics

Abstract

Dielectric and piezoelectric properties of Pb0.9La0.1TiO₃ ceramics were investigated as a function of grain size. Sintering atmosphere was controlled with changing the kind of atmosphere powder and its amount. It was confirmed that dielectric and piezoelectric properties of Pb0.9La0.1TiO₃ were strongly influenced by the sintering atmosphere. Relative dielectric constant of Pb0.9La0.1TiO₃, which was sintered in PbO-deficient atmosphere made by Pb0.9La0.1TiO₃ powder, increased with the grain size. However, the dielectric constant of the samples sintered in the PbO-sufficient atmosphere made by PbZrO₃ powder was slightly decreased with the grain size. Piezoelectric d33 constant of Pb0.9La0.1TiO₃ also showed a different trend, depending on the sintering atmosphere. It was almost constant in the range of grain size of 1.3~2.3 ㎛ when the samples were sintered in the PbO-sufficient atmosphere, while it intensively decreased with the grain size in the case of the PbO-deficient conditon.