Nanodiamond addition to chemical solution deposited YBa2Cu3O7-δ film: effect on structural and superconducting properties

The superconducting properties of YBa2Cu3O7-delta (YBCO) film can be significantly improved through the introduction of nanosized defects. In this work, the Chemical Solution Deposition (CSD) of YBCO film doped with Nanodiamond (ND) is proposed. ND introduction in YBCO (YBCO-ND) has never been reported until our recent preliminary study [1] that showed ND potential for the improvement of YBCO transport properties. Further optimizations of the YBCO-ND CSD process have been accomplished and results are illustrated in the present paper. Good epitaxial films have been obtained and a significant improvement of film morphology and superconducting properties has been observed with respect to pure YBCO. Dopant seems to have a beneficial effect on YBCO morphology. In fact, YBCO-ND films generally show denser, smoother and more connected surfaces. The good morphology corresponds to increased superconducting properties. Higher zero-field critical current densities have been measured in the temperature range from 10 K to 77 K (i.e. 18 and 13 +/- 1.2 MA.cm(-2) respectively for YBCO-ND and pure YBCO at 10 K). These results could be mainly ascribed to an improvement of the percolation path due to the increase of film density and grain coalescence. It might be supposed that ND influences the nucleation mechanisms of YBCO films facilitating c-axis orientation, but the actual role sill needs to be clarified.