The influence of a zirconia environment on the melt processing of YBa2Cu3O7−x

In the self-flux growth of YBa 2 Cu 3 O 7− x single crystals in zirconia crucibles a large proportion of the boule consists of secondary phases, from which the YBa 2 Cu 3 O 7− x crystals are then mechanically separated. The same secondary phases also occur in thick films melt processed on zirconia substrates. The nature and relative proportions of the phases depend on the starting composition, the use of crucible or substrate and growth conditions. However, there are a number of common features, which are the subject of this paper. Scanning electron microscopy EDX analysis of crystal growth boules and thick films are reported. Considerable amounts of Zr are found in the flux phases, even at relatively large distances from the crucible or substrate interface. However, large Zr-doping of the 123 phases does not occur and the superconducting properties are not adversely affected by the presence of these small amounts of Zr.