NEW CUPRATES WITH THE 1222-STRUCTURE - (CE,M)SR-2(GD,CE)(2)CU2OY (M=ZN,NI)

A new type of layered cuprate with the nominal composition (Ce(0.5)M(0 .5))Sr-2(Gd2-xCex)Cu2Oy (M = Zn, Ni) has been successfully synthesized and identified by X-ray diffraction analysis. The compounds have a te tragonal cell with the space group of I4/mmm. The lattice parameters o f a = 3.8365(1) Angstrom, c = 29.2010(4) Angstrom for (Ce0.5Zn0.5)Sr-2 (Gd1.2Ce0.8)Cu2Oy and a = 3.8389(5) Angstrom, c = 29.0548(10) Angstrom for the Ni analog were obtained from indexing the XRD patterns. By us ing the Rietveld refinement, the compounds were found possessing the s ame structure type as the common 1222 structure. Although complete CuO pyramidal planes also exist in the present compounds, the as-prepared samples are not superconducting above 15 K.