The O-1s x-ray near-edge-absorption spectra of La1.52xCaxBa1.5Cu3Oy and La1.5CaxBa1.52xCu3Oy have been measured by using synchrotron radiation. Their spectral features of the pre-edge spectra indicate that there is an electronic structure change similar to the effect of Pr in Y12xPrxBa2Cu3O7-d ; the holes on the CuO2 planes increase with the doping concentration of Ca ions; not all the excess oxygen ~for y^7.0! in the basal plane supply holes; and there is a sign of increasing, rather than decreasing, 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.
關聯:
Physical Review B (Condensed Matter and Materials Physics) 60(6), pp.4357-4362
