ELECTRON-DENSITY DISTRIBUTION IN ND2-XCEXCUO4-DELTA

The distribution of electron density in single crystals of Nd2CuO4 and changes caused by Ce doping in Nd2-xCexCuO4-delta crystals have been studied using X-ray diffraction data. Investigations have been carried out on a non-doped sample of Nd2CuO4 at 293 and 20 K, and on two crys tals of Nd2-xCexCuO4-delta at 293 K. In the non-doped sample, the elec tron density distribution shows features characteristic at the copper atom in the Cu2+ valence state and redistribution of the valence elect rons of the Nd atom due to bonding. The substitution of Nd by Ce leads to a change in the valence state of Cu and changes the whole picture of the electron density.