Beschreibung:
Y1Ba2Cu3O7-y (YBCO) samples containing boric oxide as a glass-former were prepared by the melt-cast method and investigated by electric resistivity and X-ray diffraction. Superconducting transitions were observed in samples with less than 2 mol% boric oxide, whereas those with more than this amount did not show any superconducting transition down to 15 K. X-ray diffraction experiments indicated that reaction of boric oxide with other oxides composing YBCO did not form the superconducting structure. Recovery of the superconductivity was observed in the samples doped with 2.5 and 5 mol% boric oxide when a slightly excess amount of BaO2 was added.