Relationship between Tc and hole concentration in Bi2Sr2CaCu2O8 + δ

Structure and electrical property are studied in the quenched Bi 2 Sr 2 Ca 1-x Nd x Cu 2 O 8 + δ system. The quenched samples with 0≦x≦1 have a single phase of the Bi 2 Sr 2 CaCu 2 O 8 + δ structure, as do the furnace-cooled samples. The oxygen concentration decreases slightly by about 0.05 in the chemical formula upon quenching from 800°C into liquid nitrogen. The T c remains a constant (∼90K) for x≦0.15, and decreases linearly with x in the range of 0.15≦x≦0.45, and superconductivity disappears for x≧0.45. The result for the quenched systems, if x is shifted by +0.1 in it, agrees very well with that for the furnace-cooled Bi 2 Sr 2 Ca 1-x Nd x Cu 2 O 8 + δ and Bi 2 Sr 2-x Nd x CaCu 2 O 8 + δ systems. The relationship between the T c and the hole concentration in [Cu-O] is confirmed to be universal in both the quenched and the furnace-cooled Bi 2 Sr 2 CaCu 2 O 8 + δ systems.