XPS study of RNiSb2 (R = Pr, Nd) compounds

The electronic structure of the ternary RNiSb2 (R = Pr, Nd) compounds, which crystallize in the tetragonal primitive ZrCuSi2-type structure, was studied by the X-ray photoemission spectroscopy. The R3d core-levels and the valence bands were investigated. The results for the PrNiSb2 valence band are compared with the previously calculated density of states. The obtained results indicate that the valence bands are mainly determined by the Ni3d band. The analysis of the XPS spectra of R3d5/2 and R3d3/2 based on the Gunnarsson–Schönhammer model gives the hybridization of the 4f orbitals with the conduction band. The experimental data concerning the valence band of these compounds are compared with the calculations based on the KKR-CPA method. The calculated data for the room temperature (paramagnetic region) give the peaks corresponding to the R4f states at the Fermi level EF = 0. A different distribution of the peaks corresponding to the Ni3d states is observed. For PrNiSb2 three peaks at 2.0, 2.3 and 3.5 eV are observed while for NdNiSb2 a broad maximum between 5.0 and 8.0 eV is visible. The experimental data for PrNiSb2 are in good agreement with the calculated ones while those for NdNiSb2 are not.