High-temperature X-ray diffraction analysis of morphotropic lead titanozirconates: Influence of preparation method on chemical dispersion

By means of temperature x-ray diffraction, we estimate the compositional fl uctuation in morphotropic PbZrxTi1.xO3 (PZT) solid solutions. In these syst ems, near the morphotropic phase boundary (x approximate to 0.54), the tetr agonal and rhomboedral phases coexist at room temperature, with respective constant lattice parameters and with relative amounts according to the aver age law. Because of the overlapping and the broadening of the diffraction l ines, the morphotropic PZT x-ray pattern is complex. A convenient method is to measure diagrams at 550 degreesC, temperature above Curie temperature ( 490 degreesC) for which the PZT had cubic symmetry. From the observed line broadening, a fluctuation of lattice spacing is calculated. The composition al fluctuation is then deduced from a calibration curve made out with some PZT samples whose compositions are determined by x-ray fluoresence.