SUPERCONDUCTIVITY AND PHASE-DIAGRAM OF LA2CUO4+X

X-ray diffraction and magnetic susceptibility have been studied on high quality La2CuO4 + x (x < 0.04) single crystals in the wide temperature region 4.2 < T < 300K. From this comprehensive study we revise the initial part of the phase diagram of La2CuO4 + x. Superconductivity (SC) in the system appears without phase separation (PS) and decomposition on to antiferromagnetic (AF) and metallic phases provided that good dielectric crystals have been chosen for oxygen doping. Critical temperature for that SC transition is much lower then usually observed in PS samples. So at least the initial part of the T-x phase diagram of La2CuO4 + x resembles that of La(Sr)(2)CuO4 system.