Room temperature structure of Pb(ZrxTi1-xO3) around the morphotropic phase boundary region:: A Rietveld study

We have carried out a detailed Rietveld analysis of x-ray powder diffraction data of Pb(ZrxTi1-x)O-3 (PZT) compositions across the morphotropic phase boundary (MPB) region (x=0.515, 0.520, 0.525, 0.530). It is shown that the structure of PZT is pure tetragonal for xless than or equal to0.515 with space group P4mm. In the MPB region, 0.515<0.530, the tetragonal and monoclinic (space group: Cm) phases are found to coexist as a result of a first order phase transition between the low temperature monoclinic and high temperature tetragonal phases. Further, arguments are advanced to show that the hitherto believed rhombohedral structure (F-R(HT)) of PZT for 0.530less than or equal toxless than or equal to0.62 is more likely to be monoclinic. (C) 2002 American Institute of Physics.