Dielectric and ordering behavior in PbxCa1-xTiO3

The dielectric properties and microstructure of PbxCa1-x TiO3 are reported, At room temperature, PbxCa1-xTiO3 is orthorhombic for compositions where x is 0.1 and 0.2, pseudocubic for compositions where x is 0.3 and 0.4, and tetragonal for compositions where x is greater than or equal to 0.5. TEM studies on the calcium-rich compositions reveal the presence of 1/2{100}-, 1/2{110}-, and 1M{111}-type superlattice reflections in three principal zone axes, An analysis of crystal structure, based on the atomic displacements and the ordering of lead and calcium atoms, is reported, No ordering behavior is observed for the compositions where x is 0.1 and 0.2; however, partial ordering of lead and calcium atoms occurs for compositions where 0.3 less than or equal to x less than or equal to 0.60. The dielectric measurements do not reveal any relaxer behavior; however, the addition of calcium titanate to lead titanate broadens the width of the transition region, Calculation of the diffuseness parameter, delta, from the power-law model also is presented.