Influence of Sm contamination on the superconducting properties of SmBa_2Cu_3O_(7-δ) seeded melt textured YBa_2Cu_3O_(7-δ)

摘要

A main processing aim of melt textured YBa_2Cu_3O_(7-δ)(YBCO) is to develop large grain material with a high J_c which flows over the length scale of the sample, in order to maximise the flux trapping ability of the large YBCO grains. If SmBa_2Cu_3O_(7-δ)(SmBCO) seeds are used for the solidification process contamination of the 123 matrix occurs at positions close to the seed. We report a study of the magnetic characterisation of a typical large YBCO grain, prepared by SmBCO seeded peritectic solidification, and correlate variations in the transition temperature, T_c, critical current density, J_c, and irreversibility field, B1L, with Sm concentration. The T_c of samples cut from the bulk increases smoothly with sample radius to a distance of the order of mm from the seed position which indicates a variation in Sm concentration at positions away from the seed. The local J_c and BtL are also extremely sensitive to Sm concentration in the vicinity of the seed.