Oxygen content, thermodynamic stability, and superconductivity of Hg1-xRexBa2CuO4+delta - art. no. 014508

The oxygen nonstoichiometry of single phase (Hg, Re)-1201 samples was studi ed by high-temperature thermodynamic techniques. The relevant structural fe atures and the oxygen occupancy numbers were determined by Rietveld refinem ents using x-ray and neutron powder diffraction data. Underdoped and overdo ped samples for different Re contents obtained by changing oxygen content t hrough suitable post annealing treatments enable us to analyze the effect o f both substitutions on T-c. The Re doping increases the thermodynamic stab ility of the Hg-1201 phase due to the incorporation of strongly bonded oxyg en atoms. The Re incorporation also makes it possible to easily reach the o verdoped regime, without appreciably affecting the maximum T-c. The slight decrease of the maximum T-c, may be due to the cation disorder introduced b y Re. The effect of extra oxygen in the (Hg,Re)O-delta layer on the T-c, of Hg-1201 compound is discussed.