INFLUENCE OF CE DOPING ON THE DISTRIBUTION OF THE ELECTRON-DENSITY INND2-XCEXCUO4-DELTA

Nd2-xCexCuO4-delta single crystals have been studied using X-ray diffr action data. The investigations have been carried out on a non-doped c rystal of Nd2CuO4 and Ce doped crystals of Nd2-xCexCuO4-delta. From th e structure parameters obtained, the deformation electron density dist ribution has been determined. In the Nd2CuO4 specimen this distributio n shows the peaks of localized 3d(z)2 electrons of the Cu atom, coordi nated by four O atoms in a square, which complete the Cu polyhedron to an octahedron. The distinction between the bonding of the O(1) atom i n the CuO2 plane and the O(2) atom is also observed. In the Nd2-xCe(x) CuO4-delta specimens the Ce doping causes a change of the valence stat e of the Cu atom and formation of channels with positive deformation e lectron density in the crystals.