Browsing by Author "Battat, J."
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Item Open Access Kinetics of phase transformations in lead scandium tantalate thin films(Taylor and Francis, 2004) Battat, J.; Huang, Zhaorong; Donohue, P. P.; Todd, M. A.; Whatmore, Roger W.The phase transformations from amorphous to pyrochlore to perovskite in lead scandium tantalate (PST) thin films during rapid thermal annealing process (RTA) have been studied. Volume fractions for pyrochlore and perovskite were obtained from their respective X-ray diffraction intensities. Two models assuming the starting phase being pure amorphous or pyrochlore were analysed in detail. Equations have been derived and numerical calculation used to simulate the volume fractions for each phase as functions of annealing time. Transformation parameters k and n were obtained by comparing experiment with simulation using a least-squares curve fitting technique.Item Open Access A model of phase transition kinetics in lead scandium tantalate thin films(Taylor and Francis, 2003) Battat, J.; Huang, Zhaorong; Donohue, P. P.; Whatmore, Roger W.The phase transformations from amorphous to pyrochlore to perovskite in lead scandium tantalate (PST) thin films during rapid thermal annealing process (RTA) have been studied by X-ray diffraction (XRD) techniques. The growth and decay of the pyrochlore phase, the growth of the perosvkite PST were analysed using the Avrami model. Integral equations have been derived and numerical calculation been used to simulate the volume fractions for pyrochlore and perovskite as functions of annealing time. Transformation parameters k and n were obtained by comparing the simulated to the experimental intensities using a least-squares curve fitting technique. Activation energies for perovskite formation were calculated. The results indicate that the phase transitions are diffusion-limited. TEM, SEM, and EDS were employed to study the lead loss and other factors affecting phase transitions.