EFFECTS OF MELT CONVECTION ON YBA2CU3O7-X SINGLE-CRYSTAL GROWTH BY PULLING METHOD

The melt convection phenomena in YBa2Cu3O7-x, (YBCO) single crystal gr owth by the modified pulling method (Solute Rich Liquid-Crystal Pullin g method; SRL-CP method) have been investigated by using a numerical c alculation. The finite difference method was used to calculate the ste ady state of the axisymmetric 2-dimensional incompressible viscous flu id system. In order to clarify the property of the melt convection, th e dimensional analysis was performed with changing various parameters for the calculation, such as the crystal rotation rate, the melt visco sity, etc. The intensity ratio of the forced to the natural convection in the melt could be expressed by Re(1.5)Dsc(0.7)/Gr, where Re, Gr an d Dsc were the Renolds number, the Grashof number and the diameter rat io of the crystal to the crucible, respectively. And also, the dimensi onless crystal growth interface temperature, Theta could be expressed by Theta=C Re(0.028)Pr(0.041)Gr(0.019)Dsc(0.064), where Pr was the Pra ndtl number and C was a constant. These results agreed well with the e xperimental results, and indicated that in this system, the heat trans port was mainly dominated by the forced convection. On the basis of th ese calculated results, the YBCO single crystal which was 14.5 mm x 14 .5 mm x 13 mm could be grown along the c-axis by the pulling method.