The great ability of mercury-based cuprates to accommodate transition elements eleven new superconductors Hg1-xMxBa2Cam-1CumO2m+2+δ (M V, Mo, W, Ti, Cr)

Abstract

The HgBaCuMO and HgBaCaCuMO systems have been investigated for MV, Mo, W, Ti, Cr. Eleven new superconductors Hg1-xMxBa2Cam-1CumO2m+2+δ have been synthesized at normal pressure with the 1201 structure for MTi, Mo, W and Cr, with the 1212 structure for MMo, W, Ti and Cr, and with the 1223 structure with MV, Mo, Ti and Cr. The XRD and ED investigation of these oxides shows that the a parameter of their tetragonal cell is not strongly influenced by the presence of the transition element, whereas the c parameter is significantly decreased with respect to HBC and HBCC systems, due to the partial replacement of Hg by M. The structural anisotropy in the three series of oxides, represented by the c/a ratio varies in the following way: (c/a)Cr