PREPARATION AND SUPERCONDUCTING PROPERTIES OF THE Ba2 Y1Cu3(O, F)7 -delta

Ba//2Y//1Cu//3(O,F)//7// minus // delta compounds were prepared by solid-state reaction using BaCO//3, Y//2O//3, CuO powders and one of BaF//2, YF//3 and CuF//2 multiplied by (times) 2H//2O powders. It was found by thermal and X-ray analyses that YF//3 was a better fluoridized material to make the Ba//2Y//1Cu//3(O,F)//7// minus // delta compounds compared with BaF//2 and CuF//2. Ba//2Y//1Cu//3(O,F)//7// minus // delta compounds with a small amount of fluorine were a single phase with the orthorhombic structure like the Ba//2Y//1Cu//3O//7// minus // delta compound. The superconducting transition temperature, T//c, and the lattice constants a//0, b//0 and c//0 were slightly changed by adding the fluorine content. The T//c depends on the lattice constant.