It has been known that lead titanate($PbTiO_3$) has good properties for piezoelectric and pyroelectric applications but are very porous and fragile
La-modified $PbTiO_3$ (PLT) ceramics was obtained by mixed oxide method. PLT ceramics which have high density and pure perovskite structure was obtained at the compositions with 10, 15, and 20mol% La substitution except 5mol%. The densification rate increased and the tetragonality ratio (c/a) became smaller with increasing La content.
Dielectric and pyroelectric properties of PLT ceramics with 10,15, and 20 mol% La substitution was examined. It was found that these ceramics had relatively small pyroelectric effect and figure of merit as compared with c-axis oriented thin film data. The Curie temperature decreased and the behavior of ferro-paraelectric phase transition approached a more diffuse character with an increase of La content.
The effect of the sintering condition on dielectric and pyroelectric properties was investigated in PLT ceramic with 10 mol% La substitution. The grain size change had no effect on pyroelectric figure of merit. As sintering time decreased, the behavior of ferro-paraelectric phase transition approached a diffuse character. These results can be discussed in terms of grain size effect and composition inhomogeneity.
