Magnetic field dependence of critical current density in Pt-doped YBa sub(2)Cu sub(3)O sub(7-x) thick films

The addition of platinum and the Ba sub(4)Cu sub(1+x)Pt sub(2-x)O sub(9-z) (0412) phase to melt-textured YBa sub(2)Cu sub(3)O sub(7- delta ) (YBCO) thick films has been shown to induce notable improvements in the flux pinning characteristics of the material. Transport critical current density (J sub(c)) values in excess of 7x10 super(3) A cm super(-2) at 77 K and self-field have been achieved, with volume magnetization values in excess of 9x10 super(6) A m super(-1) at 77 K and zero applied field. Measurements of both the inter- and the intra-granular flux pinning characteristics in applied fields indicate that this behaviour is greatly improved in the Pt-doped YBCO films. The enhanced flux pinning was attributed to an increase in defect densities within the matrix material, associated with a change in the morphology of Y sub(2)BaCuO sub(5) inclusions.