Structures and superconductivity of Nd0.7Sr1.3Cu(O,F)4-δ with Tc=44K and its precursor

Abstract Superstructure due to ordering of vacancies in Nd 2−x Sr x CuO 4−y (x=1.2−1.5) was investigated by XRD and TEM. There exist different ordering types in the same sample. After fluorination reaction, the ordering structure disappears. F doping induces superconductivity in Nd 0.7 Sr 1.3 CuO 4-δ (T c =44K. No SrF 2 was observed in the fluorinated products.