Ca doped YBaSrCu2.5B0.5−xSxOz series: combination effect of the cation and oxyanion doping

Abstract A series of compounds (Y 0.6 ,Ca 0.4 )BaSrCu 2.5 B 0.5− x S x O z (0.0≤ x ≤0.5) were synthesized using the solid state reaction method. The effects of calcium substitution on phase composition and crystal structure and superconductivity are studied. The combination of the cation and oxyanion substitutions, Y 3+ by Ca 2+ and [BO 3 ] 3− by [SO 4 ] 2− , can easily induce superconductivity and T c increase of 39–43 K can be obtained in the series. Compared with related Ca-free series, we can draw the conclusion that the combination of cation and oxyanion doping is superior to single doping in hole providing ability.