GROWTH SHAPE OF YBA2CU3O6-CRYSTA L FABRICATED BY THE PULLING METHOD(XSINGLE)

Continuous growth of YBa2Cu3O6+x(Y123) single crystal was achieved by the modified pulling method. The largest size of the Y123 single cryst al obtained reaches 20 mm square under 1-atmosphere oxygen partial pre ssure and 24 mm square for the NdBa2Cu3O6+x(Nd123) single crystal in a ir. Clear spiral growth patterns were observed on the crystal/liquid i nterface by AFM and STM. The growth model of the crystal was explained by the BCF model. The grown crystal was usually covered with a slow g rowth rate face such as a low index face, and the obtained crystal sha pe was cubic. Recently, we fabricated a round cornered Y123 single cry stal by keeping the growth temperature around the peritectic temperatu re. A seed crystal was at first remelted at its corner, followed by gr owth of the round cornered crystal. Along the vertical axis, the cryst al corner became wavy. The remelting process was explained by the free energy difference between the flat and square interfaces. Growth shap es of the round corner were explained by temperature-dependent growth rate anisotropy.