Superconducting YBa2Cu3O7-y (Y123) films were grown by liquid-phase epitaxy (LPE) on a NdGaO3(110) single-crystal substrate by a modified top-seeded crystal-growth method. The crystalline orientation of the epitaxially grown Y123 films depends on the growth temperature and the composition of the melt. In the case of copper-poor melt compositions (Ba:Cu=3.0:5.0 and 6.0), only c-axis oriented growth was observed, while both c-axis and a/b-axis oriented films were obtained using the melts of copper-rich composition (Ba:Cu = 3.0:6.5 and 7.0). In the latter case, the crystalline orientation of Y123 films was dependent on the temperature of the surface of the melt. At lower temperatures, c-axis orientation films were obtained, while the films showed a/b-axis orientation at higher temperatures. The mechanism of the orientation of epitaxial growth of Y123 film is explained by the change of the supersaturation of the solute at the growth interface dominated by the solubility line of the Y2BaCu05(Y211)-BaO + CuO system.
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