Abstract
The ac susceptibilities were measured on the powdered samples of La2-xSrxCuO ?? with various Sr and oxygen contents. Only the sample containing x-0.16 and y-4 showed the sharp superconducting transition at Tc=38K with a large volume fraction, f, of more than 80%. The others had rather broad transitions at lower temperatures with smaller f, while the onset temperature of the Meissner effect was close to 38K, suggesting that there existed a small amount of superconducting phases with Tc of 38K, and that the weak coupling in between by the Josephson effect took place at lower temperatures. These results may imply that only the compound with x-0.16 and y-4 is intrinsic in the superconductivity of this system.
