Ag-LnBa2Cu3O7-x (Ln = Y, Nd, Sm, Eu, AND Yb) SUPERCONDUCTOR COATINGS ON STAINLESS STEEL

Ag-doped LnBa2Cu3O7-x (Ln = Y, Nd, Sm, Eu, and Yb) films on two kinds of stainless steel substrate were prepared by the method of direct deposition and heat treatment. The critical temperatures of the samples were evaluated at 91–92 K, independent of silver content and thickness of the coating layer. The resistance of the samples decreased with silver addition. The SEM observation showed a border between the coating layer and the substrate. The elemental analysis by EPMA revealed that aluminum aggregated in the border. The diffusion of iron ions in the coating layer was hindered by the existence of the border and affected by the quantity of aluminum. The width of the border increased with increasing heat-treatment time, governed by the diffusion of metals from the metallic substrate to the coating layer. This fairly agreed with the results of impedance measurements. © 1997 Elsevier Science Ltd