MICROSTRUCTURAL EVOLUTION OF PB(ZR, TI)O3 THIN-FILMS PREPARED BY HYBRID METALLOORGANIC DECOMPOSITION

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-degrees-C to 650-degrees-C. Our films, when observed with an optical microscope, appeared to consist of two distinct phases: (1) a featureless matrix and (2) 1-2-mu-m diameter "rosettes". PZT films fired at 500-degrees-C consisted of a pyrochlore containing phase (featureless matrix) and contained no perovskite, whereas films fired at 600-degrees-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-degrees-C, the perovskite phase was observed in two forms: (1) large (almost-equal-to 2-mu-m) 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.