A new superconductor with 1222 structure (Cu1−xMx)Sr2(Y1−yCey)2Cu2Oδ (M=Ti, V, Cr, Fe, Co, Ga, Ge, Mo, Ce, W and Re)

We systematically synthesized (Cu, M)-1222 cuprates, (Cu1-xMx)Sr-2(Y1 -yCey)(2)Cu2Odelta (M = Ti, V, Cr, Fe, Co, Ga, Ce, Mo, Ce, W and Re), and succeeded for the first time in synthesizing new 1222 compounds with M = Ti, V, Cr, Co, Ge, W and Re. All samples except for the compound with Fe show superconductivity, giving the highest T-c similar to 43 K for annealed M = Re sample ((Cu0.85M0.15)Sr-2(Y0.75Ce0.25)(2)Cu2Oepsilon). We compared the T-c's with the crystal structures and investigated the difference between annealed and as-sintered samples. We point out here that T-c is related to the valencies of the M-elements and the O-Cu-O angle in the CuO2 planes. (C) 1998 Elsevier Science B.V. All rights reserved.