Effect of vapor thermolysis on microstructure development of sol-gel-derived lead zirconate-titanate (PZT) and PZT-Sr(K0.25Nb0.75)O-3 solid solutions

Ceramic granules of PZT (Pb(Zr-53,Ti-47)O-3) and fibers of SKN-doped PZT (1 Mol-% Sr(K0.25Nb0.75)O-3 substitution in PZT) were fabricated from sol-gel precursors. The transformation of the metal-organic gel to the oxide and its crystallization behavior was investigated by thermogravitmetry, and XRD. The formation of pyrochlore or perovskite phase was sensitive to the preceeding heat treatment conditions in moist atmosphere (termed vapor thermolysis). Lower thermolysis temperatures resulted in the preferred formation of metastable pyrochlore phase. Higher thermolysis temperatures favored the formation of perovskite. Investigation of sintered materials revealed a superior sintering activity for samples with pronounced intermediate pyrochlore content whereas low-pyrochlore samples remained highly porous after sintering. For constant chemical precursors the vapour thermolysis conditions (220-280 A degrees C) siginificantly affected crystallization and sintering behavior of the PZT and SKN-PZT material.