Structural and ferroelectric properties of perovskite Pb(1-x)(K0.5Sm0.5)(x)TiO3 ceramics

摘要

PbTiO3 has the highest tetragonal distortion (c/a similar to 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 practical applications. Pb(1-x)(K0.5Sm0.5)(x)TiO3 (0 <= x <= 0.5) perovskite powders were synthesized by sol- gel process, where Pb2+ was replaced by a combination of K0.5(1+) Sm-0.5(3+) (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 the reduction of 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.