Inhomogeneous Superconducting Properties of La2-xSrxCuOyExcept forx∼0.16,y∼4.0

Abstract
The ac susceptibility was measured for the powdered samples of La 2- x Sr x CuO y with various Sr and oxygen contents. Only the sample with a composition of x ∼0.16 and y ∼4.0 shows a sharp superconducting transition at 38 K having the maximum value of the Meissner volume fraction f of more than 80% of the ideal value. The samples with the other concentrations have broad transitions at lower transition temperatures with smaller f , while the onset temperature of the Meissner effect was observed to be independent of x and y , and close to 38 K, suggesting that only the compound with x ∼0.16 and y ∼4.0 shows intrinsic superconductivity in this system.