Vs. Tiwari et al., KINETICS OF FORMATION OF THE PYROCHLORE AND PEROVSKITE PHASES IN SOL-GEL DERIVED LEAD-ZIRCONATE-TITANATE POWDER, Journal of materials research, 13(8), 1998, pp. 2170-2173
Lead zirconate titanate (PZT) powder is prepared by the sol-gel method
, The formation of pyrochlore and perovskite phases is investigated by
high temperature x-ray diffraction (XRD) and thermal analysis techniq
ues. The pyrochlore phase first appears in x-ray amorphous form, and t
hen gets converted to crystalline state on annealing in air. We show t
hat vacuum annealing of the pyrolyzed amorphous PZT gel suppresses the
formation of the crystalline pyrochlore phase. This, in turn, enhance
s the kinetics of conversion of pyrochlore to perovskite, such that a
pyrochlore-free perovskite phase can be obtained by annealing at about
500 degrees C. On the other hand, if annealing is carried out in air,
a crystalline pyrochlore phase is formed, which requires annealing te
mperatures higher than 600 degrees C for transformation to the perovsk
ite phase. These observations are explained tentatively in terms of th
e oxygen stoichiometry of the two phases.