POSSIBLE EFFECT OF OXYGEN-CONTENT ON THE UNDER-DOPED CHARACTERISTICS OF THE LA2-XSRXCUO4+DELTA COMPOUND

The effect of oxygen non-stoichiometry on the superconducting characte ristics of the La2-xSrxCuO4+delta compound in the underdoped region (x <0.16) is reassessed. Although superconductivity in the La2-xSrxCuO4+d elta compound can be unambiguously attributed to the holes in the CuO2 sheet in the structure, the hole content (p(sh)) cannot be regarded a s equal to the Sr content, x, as was frequently assumed. The parabolic relation between T-c and x for La2-xSrxCuO4+delta is shown to not ful ly represent the intrinsic relation between T-c and hole content for t he p-type high-T-c cuprates, but to be related to the variation of oxy gen nonstoichiometry in the under-doped region. It is demonstrated tha t the intrinsic relation of T-c vs. p(sh) can be derived from the para bolic T-c-x relation in the under-doped region of this system, and vic e versa, provided that the variation of oxygen content with x is prope rly taken into account.