SYNTHESIS OF A SR-DOPED HGBA2CA0.86SR0.14CU2O6+DELTA SUPERCONDUCTOR USING TERNARY OXIDE PRECURSORS

Polycrystalline samples of a Sr-doped HgBa2Ca0.86Sr0.14Cu2O6+delta (de noted as Hg-1212) were prepared by solid state reaction of stoichiomet ric mixtures of HgO, Ba2CuO3+y and Ca0.86Sr0.14CuO2. The superconducti ng transition temperature (T(c)) of the as-synthesized Hg-1212 is abou t 120 K. Upon annealing as-synthesized Hg-1212 samples under an oxygen atmosphere, the T(c) increased to 124 K. Rietveld profile analysis of X-ray powder diffraction data revealed that the Hg-1212 is isostructu ral with TlBa2CaCu2O7-delta; space group P4/mmm, a = 8584 (1) angstrom and c = 12.6646 (5) angstrom. The use of ternary oxides as precursors appeared to facilitate the nucleation of the Hg-1212 phase. Using thi s precursor method, a nearly single-phasic sample of Hg-Ba2Ca0.86Sr0.1 4Cu2O6+delta was reproducibly obtained.