It is shown that in (Pb0.5Cd0.5)Sr2(Y0.5Ca 0.5)Cu2O7 and (Pb0.5Cd0.5)SrLaCuO5 cuprates, where Cu2+ ions are in pyramidal and octahedral geometry with five and six neighboring oxygens, respectively, the Cu2p3/2(2p53d10L) XPS core line is broader than that in Nd2CuO4 where Cu2+ ions are in a square planar geometry with four coordination oxygen ions, and that for (Pb0.5Cd0.5)SrLaCuO5 is the broadest. To explain these changes in the XPS Cu2p3/2 main line, two different charge transfer mechanisms from the O2p to the Cu3d orbitals are considered. For the square planar geometry (CuO4) only the O2px, y → Cu3dx2-y2 charge transfer is allowed, whereas for pyramidal and octahedral geometries an additional apical O2pz → Cu3d3z2-r2 transition could take place, and in octahedral geometry the latter transition is more significant. The valence band spectra of the cuprates also confirm this proposition.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics