Superconducting and normal conducting characteristics of (Y/sub x/Pr/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films

The ratio of Yttrium (Y) to Praseodymium (Pr) is varied in (Y/sub x/Pr/sub 1-x/)Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YPBCO) thin films to consider the relation between superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) and insulating PrBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (PBCO) thin films. The critical temperature (T/sub c/) of the superconducting YPBCO thin film is decreased by substituting more Pr in place of Y, because Pr reduces the carrier density on the CuO/sub 2/ plane in YPBCO. The electrical characteristic of the YBCO film can be explained by the weakly coupled chain model. The addition of Pr reinforces the superconducting links among the grains in the YPBCO thin film. The normal state YPBCO film-shows two types of transport systems. Behavior similar to impurity semiconductors appears at high temperatures and the variable range hopping mechanism governs their conductance at low temperatures.<>