Growth of melt-textured Nd-123 by hot seeding under reduced oxygen partialpressure

The growth of large, melt-textured Nd1+xBa2-xCu3O6+delta (Nd-123) crystals has been achieved by hot seeding and isothermal solidification under a 1% o xygen in nitrogen atmosphere. These crystals, which exhibit a sharp, facete d growth interface, were grown epitaxially from a small Nd-123 single cryst al seed placed on the sample surface at elevated temperature. The growth le ngth of the melt-processed crystal was directly proportional to the isother mal holding time (approximately 17 h), as is observed for the growth of YBa 2Cu3O7-delta (Y-123). The variation of growth rate with undercooling for th is material was linear. however, in contrast to the parabolic dependence ob served for Y-123 crystals grown in air. The growth rate of Nd-123 under red uced oxygen was consequently lower than that of Nd-123 and Y-123 grown in a ir at relatively high values of undercooling. Evaluation of the experimenta l data against a solidification models suggested that the interface kinetic s are responsible, at least in part, for the observed growth features in ho t-seeded Nd-123 crystals. This was attributed to the difference in oxygen p artial pressure under the respective growth atmospheres, rather than to the species of rare-earth element in the compound.