Crystal Structure Refinement of (Pb_1-xCa_x)ZrO₃ by the Rietvelt Method

Abstract

Superlattice structures in rhombohedral perovskite (Pb 1- x Ca x )ZrO 3 , which has high dielectric constant with small temperature coefficient and high Q value at microwave frequencies, were refined by the X-ray Rietvelt powder profile analysis. The superlattice structure is caused by slight displacement of lead and zirconium ions from the ideal perovskite sites, together with twisting and deformation of oxygen octahedra. The Q value of (PbCa)ZrO 3 at microwave frequencies has no relation to the formation of the superlattice structures, as indicated by the absence of cation ordering.