REACTION-MECHANISMS IN THE FORMATION OF LEAD ZIRCONATE-TITANATE SOLID-SOLUTIONS UNDER HYDROTHERMAL CONDITIONS

Reaction mechanisms in the formation of PZT solid solution were studie d under hydrothermal conditions (Pb/(Zr + Ti) = 1.0 to 1.9, Zr/Ti = 0/ 10 to 10/0, 1M to 5M KOH, 100-degrees to 220-degrees-C, 2 h). A yellow tabular crystallite with tetragonal symmetry and Pb/Ti almost-equal-t o 2 was formed at 100-degrees to 130-degrees-C. A PZT crystallite was formed just above 150-degrees-C. The crystallite was a mixture of Ti-r ich PZT and Zr-rich PZT phases. When the temperature and KOH concentra tion were increased, the composition of the PZT product tended to be h omogeneous. The PZT in the morphotropic phase boundary zone was formed at Zr/Ti = 5/5, 5M KOH, 220-degrees-C, 2 h. Neither PbTiO3 nor PbZrO3 was detected as a separate phase under the above hydrothermal conditi ons.