YBA2CU3O7-X SINGLE-CRYSTAL GROWTH BY THE PULLING METHOD WITH CRYSTAL ROTATION EFFECT CONTROL

YBa2Cu3O7-x (Y123) single crystals have been grown by the modified pul ling method (Solute Rich Liquid Crystal Pulling method, SRL-CP). For f urther superconductor device application, it is important to establish a technique that enables us to produce larger Y123 single crystals co nsistently. We have investigated the relationship among the crystal si ze, the crystal rotation rate, the flow pattern in the melt, and the t emperature at the crystal growth interface experimentally. Increase of the crystal diameter and/or the crystal rotation rate increased the s trength of the forced convection in the melt, and as a result, the tem perature at the crystal growth interface increased. This resulted in a reduction of the crystal growth rate. On the other hand, the forced c onvection should be kept high enough to prevent floating particles att aching to the growing crystal. Therefore, in order to grow a larger si ngle crystal, it was necessary to control the crystal rotation rate ac cording to the change of the crystal diameter with time. We succeeded in crystal pulling along the c-axis of a relatively large Y123 single crystal which was 17 mm X 17 mm and 8 mm in length.