Growth and Characterization of Large REBa<SUB>2</SUB>Cu<SUB>3</SUB>O<I><SUB>y</SUB></I>(RE=Y, Yb) Crystalline Films by Liquid Phase Epitaxy Process

Growth conditions for liquid phase epitaxy (LPE) growth were investigated in order to grow a large REBa2Cu3Oy(REBCO, RE=Y, Yb) film with high quality. Both a thermal stability of the seed film and an appropriate supersaturation to avoid any undesired nucleation should be maintained to grow a high quality film. Especially in the case of growing a large film, it was suggested that the peritectic temperature (Tp) of a grown crystal should be lower than that of the seed film to satisfy the above requirements. We selected a (Y, Yb)BCO mixed crystal system to grow from the YBCO seed film, since the Y1−xYbxBa2Cu3Oy system is a homogeneous solid solution, and the Tp decreases with increasing the x value. A large LPE film of 2-inch in diameter was successfully grown. The composition of the film grown in this work was confirmed to be Y0.86Yb0.14Ba2Cu3Oy. The growth rate distribution along the lateral direction of the film was observed, which was enhanced with increasing the rotation rate during the growth. This phenomenon could be explained by the heat flux from the hot region in the liquid due to the forced convection, which might be stronger for the case of rotating a large substrate. The grown film had both a high crystallinity and its high in-plane uniformity. The films also exhibited excellent superconducting properties with a critical temperature of 92 K and a critical current density of over 109 A/m2 at 77 K in 0 T. These characteristics satisfy the requirements for the substrate of the future superconducting devices.