CHARGE-TRANSFER IN NIXPT1-X ALLOYS STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY

The charge transfer between Ni and Pt atoms in the Ni-Pt alloys is studied by the core-level shifts of Ni2-rho-3/2 and Pt4f7/2 x-ray photoelectron spectra. From the analysis considering the final-state relaxation energy explicitly, we conclude that the amount of the charge transfer is, in general, very small for these alloys. We also find that the intra-atomic charge transfer between nd and (n + 1)s levels in the same atom is more important than the interatomic charge transfer from one kind of atom to the other. As the concentration of the Ni or Pt atom is diluted, its valence-electron configuration approaches that of the free atom by gaining (n + 1)s electrons at the expense of nd electrons, presumably due to the decreased hybridization between d electrons of like atoms. The valence-band spectra measured as a function of the composition are found to be well represented by the weighted superposition of the densities of states of pure Ni and Pt metals.