O-1s x-ray near-edge absorption spectroscopy studies of La1.5-xCaxBa1.5Cu3Oy and La1.5CaxBa1.5-xCu3Oy

The O-1s x-ray near-edge-absorption spectra of La1.5-xCaxBa1.5Cu3Oy and La1 .5CaxBa1.5-xCu3Oy have been measured by using synchrotron radiation. Their spectral features of the pre-edge spectra indicate that there is an electro nic structure change similar to the effect of Pr in Y1-xPrxBa2Cu3O7-delta; the holes on the CuO2 planes increase with the doping concentration of Ca i ons; not all the excess oxygen (for y greater than or equal to 7.0) in the basal plane supply holes; and there is a sign of increasing, rather than de creasing, the holes around the apical oxygen O(4) with the increase of the replacement of Ba by La on the Ba sites, an indication of a redistribution of holes. [S0163-1829(99)03930-2].