Perovskite Formation Process in Pb(Ti⋅Zr)O₃ Ceramics Containing SiO₂

Abstract

Influence of SiO₂ addition on formation process of Pb(Ti⋅Zr)O₃ solid solution was studied. Powdered PbO, TiO₂, ZrO₂ and SiO₂ were used as raw materials. The process was determined from the variation of X-ray diffraction patterns and that of dilatometric dimensional change with heating temperatures.
If the materials excluding SiO₂ were mixed, Pb(Ti⋅Zr)O₃ was synthesized, passing through formations both of PbTiO₃ and PbZrO₃. However, when the materials including SiO₂ were mixed, the PbZrO₃ formation was suppressed, accompanying by a decrease of Pb(Ti⋅Zr)O₃ formation temperature.
The difference seems to be caused by the appearance of a liquid phase formed by the co-existence of SiO₂ and PbO, which occurs during the Pb(Ti⋅Zr)O₃ formation process. Reaction observed at the contact surface of two green compacts, consisting of SiO₂-PbO as well as of Pb(Ti⋅Zr)O₃, was in line with the assumption.