YBa2Cu3O6 + x and Y2BaCuO5 composites obtained by the partial melting zone method

Improvements in obtaining YBCO single domains using the partial melting zone method

“…The precursor bars used in this work were obtained from YBa 2 Cu 3 O 6+x powder. Details of the initial conformational sinterization of the 100 mm long and 3.5 mm diameter cylindrical samples have been fully described in a previous paper [4] and are only outlined here. The 15% by weight of all the samples described in the present paper corresponds to additions of Y 2 BaCuO 5 (hereafter Y211) which was found to be the optimum ratio for refining the distribution of Y211 precipitates and for obtaining more stable morphologies [4,5].…”

“…The partial zone melting procedure produces continuous melt textured Y123 longitudinal samples using a narrow hot zone that is moved through this sample. This produces liquid migration, which hinders the stable and continuous solidification process of the samples [1,3,4]. The migrated liquid comes from the partially melted region, and is capillarily absorbed by both of the adjacent non-melted parts, which are still made up of the porous aggregate of small Y123 grains resulting from the initial conformational sinterization of the bars at temperatures of between 870 • C and 940 • C [4].…”

“…This produces liquid migration, which hinders the stable and continuous solidification process of the samples [1,3,4]. The migrated liquid comes from the partially melted region, and is capillarily absorbed by both of the adjacent non-melted parts, which are still made up of the porous aggregate of small Y123 grains resulting from the initial conformational sinterization of the bars at temperatures of between 870 • C and 940 • C [4]. The density of this porous aggregate is 55% of the theoretical density of the Y123.…”

“…Optimal performance can only be achieved using samples with a well-textured microstucture. There are several methods for obtaining large single domains in Y123 samples, but the partial melting zone technique [1][2][3][4] seems to be one of the most appropriate. In all of these procedures a longitudinal sample is moved through a narrow hot zone with a temperature gradient that melts and recrystallizes the sample sequentially along its length.…”

“…Capillary liquid migration makes it difficult to obtain a completely stable and continuous recrystallization of Y123 in this kind of process [4]. In this paper, two alternative methodologies are applied and appear to make a significant contribution towards resolving this problem.…”