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Interfacial reactions in PZT/Pd/PZT sandwich structures
Author(s) -
YAO L. G.,
BROOK R. J.
Publication year - 1995
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1995.tb03563.x
Subject(s) - materials science , foil method , lead zirconate titanate , phase (matter) , eutectic system , monoclinic crystal system , tetragonal crystal system , scanning electron microscope , analytical chemistry (journal) , energy dispersive x ray spectroscopy , microstructure , chemical engineering , composite material , crystallography , ferroelectricity , dielectric , crystal structure , chemistry , optoelectronics , engineering , organic chemistry , chromatography
Summary The interfacial reactions of palladium foil and lead zirconate‐titanate (PZT) were studied using samples with a sandwich structure in the temperature range 1373–1523 K and under conditions where no lead is lost to the environment. The interfacial reactions were analysed using scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction and wavelength‐dispersive X‐ray spectroscopy analysis. The density of the PZT powder phase increased with increasing temperature and, when sintered above 1373 K, reached over 95% of the theoretical density of PZT. The weight loss of pellets was less than 0·8% when sintered below 1523 K. The degree of interfacial reactions became more severe with increasing temperature, as indicated by an expanding reacted region. The reaction at the PZT side of the Pd/PZT interface involved the decomposition of PZT into a monoclinic ZrO 2 phase, PbO and a lower x ‐value Pb(Zr x Ti 1 _ x )O 3 composition. Three distinguishable microstructures exist on the Pd side when sintered below 1473 K: a thin layer of PbPd 3 phase, a Pd–Pb solid solution zone and an unreacted region. Only the cubic PbPd 3 eutectic structure was found when sintered above 1473 K. The oxidation of palladium occurred during interfacial reactions, expedited by increasing temperature and resulting in the formation of the tetragonal PdO phase and the hexagonal PbPdO 2 phase. A model for the overall reaction is proposed involving decomposition of the PZT, migration of PbO and diffusion of Pb into Pd foil.