CASIO3 AS A SUBSTRATE MATERIAL FOR BA-Y-CU-O SUPERCONDUCTING OXIDE-FILMS

The reactivities of Ba2YCu3O7-x with BaZrO3 and CaSiO3 were studied to develop a substrate material for superconducting oxide films. It was found that BaZrO3 and CaSiO3 were less reactive to Ba2YCu3O7-x and the onset critical temperature of Ba2YCu3O7-x remained unaltered after heating in contact with these materials at 1223 K. Although BaZrO3 was less reactive than CaSiO3, BaZrO3 was unsuitable for the substrate of Ba2YCu3O7-x films because of the large difference of the thermal expansion coefficient. On the other hand, the thermal expansion coefficient of CaSiO3 is almost the same as that of Ba2YCu3O7-x, High-T(c) superconducting oxide films were prepared easily on the CaSiO3 substrate by the conventional dipping-pyrolysis method. As a result, mixed oxide, CaSiO3, is one of the promising materials for the substrate of Ba2YCu3O7-x films because of its low cost, low reactivity, and comparable in thermal expansion coefficient.