MELT-PROCESSED YBA2CU3O7-X SUPERCONDUCTORS

The superconducting YBa2Cu3O7-x samples were prepared by an Arc-Cast-A nnealing (ACA) and Arc-Quench-Powder-Growth (AQPG) processes as modifi cations of QMG and MPMG techniques. Pellets of YBa2Cu3O7-x were quench ed by arc-casting in a water cooled copper mould and then the solidifi ed rods were annealed at different temperatures and times to store the superconductivity. Annealed at an appropriate temperature the cast ro ds showed rising superconducting properties with increasing the anneal ing time. Some of the rods after solidification were crushed to give p owder which was compacted and then subjected to a melt growth process. As a result of this processing, large grained textured YBCO supercond uctors with dispersed 211 inclusions in the superconducting grains wer e produced. The microstructure and physical properties of these ACA an d AQPG samples were investigated when subject to various temperature c ycles. It was found that the volume fraction and size distribution of the second phase inclusions were dependent upon the maximum temperatur e during the melt growth process. The critical current density (J(c)) for ACA and AQPG samples was estimated from magnetization ACA sample. (C) 1997 Elsevier Science S.A.