Crystallization mechanism of Nd1+x,Ba2-xCU3O7-y and YB2CU3O7-y films deposited by metalorganic deposition method using trifluoroacetates

YBa2Cu3O7-y(Y123) and Nd1+xBa2-xCu3O7-y (Nd123) films were deposited by the metalorganic deposition method, and the growth mechanism of these films was investigated by high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. The Y123 and Nd123 films were prepared by spin-coating LaALO(3) (001) and SrTiO3 (STO) (001) substrates, respectively, with solutions including trifluoroacetates. Then, the samples were heat treated at 673 K in a humid O-2 gas flow to form amorphous precursor films. Finally, the precursor films were heated at higher temperatures for 0-30 min in a humid Ar/O-2 gas flow and cooled rapidly from those annealing temperatures. It was found that CuO crystals with a size of 10-20 nm are segregated in the Y123 and Nd123 amorphous precursor films. In the Y123 quenched film prepared by cooling the precursor film rapidly after the heat-treatment at 1048 K for 30 min, a polycrystalline film including Y2Cu2O5, BaF2, and CuO crystals was found to be generated on the c-axis-oriented Y123 film. In contrast, in the Nd123 quenched films, (Nd,Ba)(2)CuO4(Nd201) phase was found to be formed first on the surface of the STO substrate. In conclusion, the c-ay-is-oriented Y123 film is formed by diffusion and reaction of Y2Cu2O5, BaF2, and CuO crystals, and the Nd201 phase reacts with BaF2 and CuO crystals in a humid atmosphere to form a c-axis-oriented Nd123 film.