Effect of Mg addition on superconducting properties of Ba-Y-Cu-O ceramics prepared by the melt quenching method

We examined the effect of Mg addition on superconducting properties of Ba 2 YCu 3 O x ceramics prepared by the melt quenching method in order to clarify why it is very difficult to prepare superconducting Ba-Y-Cu-O thin films with a T c around 90 K on MgO substrates at processing temperatures around 900°C. We found that a very small amount of the Mg element could be introduced into Ba 2 YCu 3 O x crystals so that the values of the T c (zero) would be consequently depressed to 70–75 K.