Comparison of electronic structures of ScAl₃ and ScRh ₃: X-ray photoelectron spectroscopy and ab initio band calculation

The electronic structure of ScAl₃ was compared with that of ScRh₃, where the electronegativity difference between the two elements in ScAl₃ is smaller than that in ScRh₃. The Al 2p and Sc 2p XPS for ScAl₃ have clear plasmon loss peaks as the Al 2p peak for the elemental Al, but Sc 3p spectrum for ScRh₃ has a featureless energy loss profile as the Sc 2p peak for the elemental Sc. The electronic structures in the valence and conduction band for ScAl₃ and ScRh₃ are calculated by ab initio band calculation method. The partial density of states of Sc 3d for ScAl₃ is higher than that for ScRh₃. The center of gravity of Sc 3d for ScAl₃ is located at lower binding energy side than that for ScRh₃. The electron density map for ScAl₃ shows that between Sc and Al atoms there is a ridge with two minimum points. On the other hand, Sc-Rh bond in ScRh₃ has one minimum point. It indicates that the bonds between Sc and Al atoms are highly covalent.