Superconducting properties versus oxygen content in a Sr-doped HgBa2Ca1-xSrxCu2O6+δ

Abstract

Polycrystalline samples of HgBa2Ca1-xSrxCu2O6+δ were prepared by solid state reaction of HgO, Ba2CuO3+δ and Ca1-xSrCuO2 (x=0.14) in an evacuated silica tube. The as-synthesized sample has a Tc of 120 K and has tetragonal symmetry ( P4 mmm) with lattice parameters of a=3.8584(1) A ̊ and c=12.6646(5) A ̊. After annealing under O2 at 250 °C for 8 h, the Tc was enhanced to 124 K. The content of oxygen uptakes is about 0.11, which was estimated by a TGA analysis. However, the X-ray powder diffraction data and the Raman spectra of both as-synthesized and oxygen-annealed samples did not show any substantial difference. © 1994.