Properties of Ca-doped Bi2+xSr2−xCuO6+δ

Abstract Specific-heat measurement is performed for Ca-substituted samples for Sr in Bi 2.1 Sr 1.9− y Ca y CuO 6+ δ . Specific heat anomaly associated with the superconducting transition is observed for the samples for y  = 0.8, 0.95 and 1.0. The anomalies are consistent with the behavior of the magnetic measurement and suggest the bulk effect of the 80 K-class superconductivity.