THE CONTROL OF GROWTH ORIENTATION DURING THE PRODUCTION OF MELT-TEXTURED YBCO QUASI-SINGLE CRYSTALS

Melt texturing is a well-developed, if not fully understood, technique for the production of single crystals of Y1Ba2Cu3O7-delta. Although t his technique can produce single crystals of up to 2 mm diameter by 25 mm in length, problems remain. For example, it is difficult to contro l the orientation of the crystal relative to the rod in which it grows , it is important that the crystal is oriented so that the a-b planes lie along the bar, thus maximizing the current-carrying capability of the material. This paper reports on experiments in the use of oriented seed crystals to achieve the correct single-crystal orientation relat ive to the bar and highlights the problems associated with the use of seed crystals.