  PbTiO3 has the highest tetragonal distortion (c/a=1.064) and highest
spontaneous polarization among perovskite titanates. But, it is hazardous and
hence one needs to reduce Pb content by substituting or reducing Pb content for
use in applications. Pb(1-x)(K0.5Sm0.5)xTiO3 (0&x&0.5) perovskite powders were
synthesized by sol-gel process, where Pb2+ was replaced by a combination of
K+10.5Sm+30.5 (equivalent charge and comparable ionic radius) providing an
excellent substitution model to study changes in structural and electrical
properties. Vibrational properties and dielectric properties are modified with
substitution. A polar tetragonal to a nearly nonpolar cubic phase transition
decreases to lower temperatures with substitution due to reduces the lattice
strain with substitution. Ferroelectricity is retained even for x=0.5, which
has a nearly cubic phase and makes the material technologically important.
