Magnetic field dependence of critical current density in Pt-doped YBA2Cu3O7-x thick films

The addition of platinum and the Ba4Cu1+xPt2-xO9-z (0412) phase to melt-textured YBa2Cu3O7-δ (YBCO) thick films has been shown to induce notable improvements in the flux pinning characteristics of the material. Transport critical current density (Jc) values in excess of 7x103 A cm-2 at 77 K and self-field have been achieved, with volume magnetization values in excess of 9x106 A m-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 Y2BaCuO5 inclusions. (author)