CRYSTAL-STRUCTURE AND SUPERCONDUCTIVITY OF (HG0.5PB0.5)S2(A)(SR1-XLAX)CU2OZ

An Hg-based superconducting cuprate (Hg0.5Pb0.5)Sr-2(Sr1-xLax)Cu2Oz ha s been synthesized. X-ray diffraction patterns indicate that the 1212- compound exists only in a narrow composition range of 0.45 less than o r equal to x less than or equal to 0.55. Rietveld refinement based on the space group P4/mmm gives tetragonal lattice parameters of a = 3.86 9(7) and c = 12.14(2) Angstrom and a chemical composition of 0.28Cu0.2 2)(Sr0.85La0.15)(2)(Sr0.44La0.56)Cu2O6.56 for the compound of x = 0.55 . Electrical resistivity measurements show that the sample with x = 0. 55 becomes superconducting after annealing in O-2 with onset T-c of 97 K.