SUPERCONDUCTIVITY AND PHASE-SEPARATION IN LA2CUO4+X

It has been observed that the superconducting properties of the La2CuO 4+x (x less than or equal to 0.04) system depend substantially on how the excess oxygen is distributed in the sample: uniformly or in a mann er which results in the formation of a new phase. Precise measurements of the magnetic susceptibility of oxygenated La2CuO4+x crystals, comb ined with data found previously, lead to a revision of the phase diagr am of this system. (C) American Institute of Physics.