This study investigated the effect of excess PbO and post-annealing on the crystallinity and the microstructure of Pb(Mg_1/3Nb_2/3)O₃ (PMN) epitaxial thin films. PMN thin films were deposited on SrTiO₃ (STO) (001) substrates using a chemical solution deposition (CSD) process with rapid thermal annealing (RTA) of spin-coated metallo-organic decomposition (MOD) solutions. The nominal film composition was Pbx(Mg_1/3Nb_2/3)O₃ (x = 1.0 or 1.1). All films showed the (001)_PMN//(001)_STO, [001]_PMN//[001]_STO epitaxial relationship and were single phase perovskite PMN without any pyrochlore phases. The Pb_1.1(Mg_1/3Nb_2/3)O₃/SrTiO₃ thin film post-annealed at 973 K with facing treatment showed the highest crystallinity of 0.8° in full width at half maximum (FWHM) of the 002_PMN rocking curve. Transmission electron microscopy (TEM) revealed PbO nanoparticles on the surface of the PMN thin films. The film composition was almost stoichiometric. On the other hand, the Pb_1.1(Mg_1/3Nb_2/3)O₃/SrTiO₃ thin film post-annealed at 973 K without facing treatment showed crystallinity of 1.0° and no PbO nanoparticles. The film composition was almost stoichiometric. These results indicate that the excess PbO is not incorporated into the PMN films. Instead, it volatizes from the film surface, which improves the crystallinity and inhibits the PMN decomposition.

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This study examined improvement of the crystallinity and the decomposition mechanism for the Pb(Mg_1/3Nb_2/3)O₃ (PMN) thin films using chemical solution deposition (CSD) technique with a metallo-organic decomposition (MOD) solution. The PMN thin film crystallinity increases with higher annealing temperature, but improvement is slight at temperatures higher than 700°C. The facing annealing has a distinct effect on the crystallinity of PMN thin film at 650°C, which is the lowest annealing temperature examined in this study. The ratio of the pyrochlore phase has a peak at 750°C with or without the facing annealing. The facing annealing also has a distinct effect on PMN thin film decomposition at 800°C. Improvement of the crystallinity and of the homogeneity of the morphology of PMN thin films deposited at 650°C was possible under the facing condition. The decomposition occurs locally, and the residual PMN region has high crystallinity and stoichiometry. The atomic structure of the PMN lattice has a fluctuation that is characteristic in the relaxor, which is related to the polar-nano region (PNR). The chemically ordered region (COR) also appears in PMN even at a lower annealing temperature than that of bulk relaxor materials.

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