CRYSTAL-STRUCTURE OF SR0.875ND0.125CUO2-DELTA SUPERCONDUCTING THIN-FILMS

The crystal structure of Sr0.875Nd0.125CuO2-delta superconducting thin film was determined by x-ray diffraction. The intensity data were collected by four-circle x-ray diffractometry and the absorption correction for a thin platelike crystal of 780 angstrom thick was made. The structure was found to belong to space group P4/mmm with a = 3.920(1) angstrom, c = 3.418(1) angstrom, and Z = 1, which is almost identical with that of Ca0.84Sr0.16CuO2. The Cu-O coordination was found to be square planar without detectable buckling of the plane and no apical oxygen ions were observed. The occupation factors of Sr and Nd were slightly less than the nominal ones. The anisotropic thermal parameters for Sr, Nd, and Cu ions were elongated along the c direction, indicating the crystallographical two dimensionality of the infinite-layer structure.