NEW BARIUM-FREE MERCURY-BASED HIGH-T-C SUPERCONDUCTORS (HG,MO)SR-2(CA,Y)(N-1)CUNOY AND HGSR2(CA,Y)(N-1)(CU,RE)(N)O-Y (N=1 AND 2)

New families of barium-free mercury-based oxide superconductors were found in the HgSr2Can-1CunOy (n=1, 2) systems. The 1201-type compounds (n=1) were structurally stabilized by partial substitution of Mo for the Hg site or Re for the Cu site. These 1201-type compounds showed a superconducting transition at 60-70 K. The 1212-type compounds (n=2) with T-c of approximately 100 K were also synthesized by substitution of Mo or Re for the Hg or Cu, and Y for the Ca sites. Such a simultaneous Y doping was necessary to obtain 1212-type single-phase samples, while it seemed to result in electron carrier doping to the system. As was recently pointed out by the present authors in (Hg, Cr)Sr2CuOy, the Sr based compounds prepared in this study were also very stable during the synthesis and no deterioration was recognized after the preparations in sharp contrast to Ba containing compounds.