Oxygen content, thermodynamic stability, and superconductivity of Hg1ÀxRexBa2CuO4¿d

A. SERQUIS; A. CANEIRO; A. BASSET; S. SHORT; J.P. HODGES; J.D. JORGENSEN

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2000 vol. 63 p. 14508 - 14517

1098-0121

The oxygen nonstoichiometry of single phase ~Hg, Re!-1201 samples was studied by high-temperaturethermodynamic techniques. The relevant structural features and the oxygen occupancy numbers were determinedby Rietveld refinements using x-ray and neutron powder diffraction data. Underdoped and overdopedsamples for different Re contents obtained by changing oxygen content through suitable post annealing treatmentsenable us to analyze the effect of both substitutions on Tc . The Re doping increases the thermodynamicstability of the Hg-1201 phase due to the incorporation of strongly bonded oxygen atoms. The Re incorporationalso makes it possible to easily reach the overdoped regime, without appreciably affecting the maximum Tc .The slight decrease of the maximum Tc may be due to the cation disorder introduced by Re. The effect of extraoxygen in the (Hg,Re)Od layer on the Tc of Hg-1201 compound is discussed.