Effects of doping hole concentration in bismuth-contained superconducting cuprates

The relation between T-c and doping hole concentration can be controlled by the substitution of ions Ba for Sr, Ca and ions Pb for Bi in Bi-contained superconductors. The liquid nitrogen quenching Pb doped samples showed T-c slight higher than that of furnace-cooled samples. The T-c reached maximum values at optinum hole concentration and there are changed by doping holes from one compound to another. The parabollic dependence of T-c on the doping concentration may be universal in many high-T-c superconducting cuprates.