Hole localization and superconductivity in La2CuO4+delta

Hall coefficient of the oxygen-intercalated La214 cuprate was measured at r oom temperature and 77.4 K for delta = 0.015 - 0.110. The Hall number, defi ned as a quantity inversely proportional to the Hall coefficient. increased linearly with delta for delta < 0.030. However. for <delta> > 0.030. it wa s observed to be lower than the expected increase of hole carriers with inc reasing d This indicated the existence of localized holes in the electronic ally phase separated superconducting phases. Our resistivity and the thermo power measurements were also consistent with this conjecture.