A STUDY OF SUPERCONDUCTIVITY IN Y-Ba-Cu-F-O SYSTEM

High temperature superconductivity, up to 258K, was observed in the Y₁Ba₂Cu₃F₂xO_7-x-δ(0.2≤x≤1) bulk materials prepared by means of conventional ceramic-technique. X-ray diffraction analysis shows that these materials are multiphase. It is believed that to obtain a high T_c superconducting material with T_c near room temperature is possible. though the high T_c state of samples is now very unstable.