Synthesis, characterization and superconducting properties of mercury-strontium based cuprates.

In recent years, the study of Ba-free Hg/Sr-based cuprates,(Hg,M)Sr2Can-1CunO2n+2+d; M = Cr, Mo or Re; designated as (Hg,M)/Sr-1201, for n = 1 and (Hg,M)/Sr-1212, for n = 2, has continued to draw significant attraction. Some of the key issues of interest are: (i) the stabilization of Hg/Sr-12(n-1)n-type phases at normal and low pressures, (ii) realizing superconductivity with highest Tc and (iii) studying an important issue arising from the different studies that is currently being debated, i.e., the presence (or absence) of trace amounts Cu at the Hg-site. Hence, the present investigation is focussed on synthesis, characterization and superconducting (SC) properties of (Hg,M)/Sr-1201 and (Hg,M)/Sr-1212 systems. (Hg0.7Cr0.3)Sr2CuO4+d showed a maximum Tconset of 60 K, and that Tc was not affected by the subsequent Ar or O2 annealing treatment. Remarkably, the annealed samples show significant improvement in the diamagnetic signal. In (Hg1-xMox)Sr2CuO4+d system, a maximum Tconset of 66 K was obtained for x = 0.15 samples. For x = 0.30, Tconset was found to be 36 K. More Info

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