The Effect of Platinum and Excess 211 Phase on the Loss of the Liquid Phase in Melt Textured Yba₂Cu₃O₇₋ₓ

Platinum is an important additive in YBa/sub 2/Cu/sub 3/O/sub 7-x/ [123] powders for melt processing and growth of large oriented crystals, but its role in liquid loss during the growth cycle is poorly understood. A series of experiments were conducted to determine how platinum effects liquid loss, and to study the solubility limit of platinum in 123. Both atomically mixed and solid state platinum sources were compared. Crystals were grown on a nonreactive setter so that liquid loss could be clearly distinguished by weight from reaction products with the setter. Based on weight loss studies there was little difference between atomically added platinum and by adding platinum powder to the 123 powder. In samples with no excess Y/sub 2/BaCuO/sub 5/ (211), weight loss due to liquid loss was at a minimum of 3.8 percent with 0.3 weight percent platinum content. Examination with an electron microprobe reveals different microstructures for the two different methods of platinum additions.