a1 Sandia National Laboratory, P. O. Box 5800, Albuquerque, New Mexico 87185
a2 Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802
We report on the microstructural analyses of chemically prepared Pb(Zr0.53Ti0.47)O3 (PZT 53/47) films. Although several techniques were used to analyze films, transmission electron microscopy (TEM) was emphasized. Phase evolution of these films, fabricated using hybrid metallo-organic decomposition (HMD), was determined by processing films at temperatures ranging from 500 °C to 650 °C. Our films, when observed with an optical microscope, appeared to consist of two distinct phases: (1) a featureless matrix and (2) 1–2 μm diameter “rosettes”. PZT films fired at 500 °C consisted of a pyrochlore containing phase (featureless matrix) and contained no perovskite, whereas films fired at 600 °C were ferroelectric and were approximately 90% perovskite (rosettes) by volume. Our TEM analysis showed that the pyrochlore-containing phase consisted of interpenetrating nanocrystalline pyrochlore and amorphous phases, both with dimensions on the order of 5 nm. For PZT films processed at 650 °C, the perovskite phase was observed in two forms: (1) large (2 μm) rosette structures containing 30 nm pores and (2) dense equiaxed particles on the order of 100 nm. We propose that phase evolution—with increasing temperature of HMD PZT 53/47 films—consists of the following steps: (1) phase separation, probably occurring in solution, (2) pyrochlore crystallization, (3) heterogeneous nucleation of perovskite PZT, and (4) homogeneous nucleation of perovskite PZT.
(Received June 14 1991)
(Accepted February 26 1992)