Abstract
Using the sealed silica-tube method, ive have successfully synthesized Hg-1212 superconductors (Hg0.65V0.35)Sr-2(Ca1-xNdx)Cu2O2 in the range of 0.35 less than or equal to x less than or equal to 0.55, Rietveld refinement on the X-ray diffraction data is carried out on the basis of tetragonal space group P4/mmm. Refined occupation factors of V in the Hg site and Nd in the Ca site as well as of oxygen at (1/2,1/2,0) on the (Hg, V)Oa layer give a chemical composition (Hg0.61V0.39)Sr-2(Ca0.41Nd0.59)Cu2O6.78 for the as-prepared sample with the nominal composition of (Hg0.65V0.35)Sr-2(Ca0.55Nd0.45)Cu2O2. The variation of T-c with x and T-c enhancement after O-2 annealing indicate that the compounds are in the underdoped region, The highest onset T-c of 105K is attained in the O-2-annealed sample with x = 0.35.