THE GROWTH OF YBA2CU3O7-DELTA SINGLE-CRYSTALS WITH THE AID OF A NACL-KCL FLUX

Different quantities of mixed alkali halide flux have been used to grow single crystals of YBa2Cu3O7-delta. The superconducting properties of the crystals have been determined in the as-grown state and after post growth oxygen annealing, using AC susceptibility. The crystals were found to be relatively large in size, 8 x 7 x 2 mm, and were confirmed as being single crystals by the use of Laue X-ray diffraction. The size, the quality and the superconducting transition temperature of the crystals were found to depend not only on the proportion of flux but also on the precise heat treatment cycle, involving the maximum temperature and cooling rate. X-ray micro-analyses have confirmed the presence and identity of a number of inclusions.