Electronic structures of perovskite-type ScRh 3B x (0≤ x≤1): X-ray photoelectron and nuclear magnetic resonance spectroscopies and ab initio band calculation

Abstract

Polycrystalline samples of ScRh 3, ScRh 3B, and their solid solution, ScRh 3B x (0< x<1) were synthesized by an arc-melting method. Sc 2p, Rh 3d, B 1s and valence band X-ray photoelectron spectra were taken for the samples fractured in situ in an electron spectrometer. The binding energy of Sc 2p 3/2 linearly increased with x from 398.4 5 to 399.3 0 eV, and its FWHM did not change with x. The binding energies of Rh 3d 5/2 for ScRh 3, and ScRh 3B x ( x≠0) were 306.7 and 306.9 eV, respectively. The binding energy of B 1s did not depend on x. Knight shifts of Sc and B in nuclear magnetic resonance spectra for 45Sc and 11B nuclei were obtained. The Knight shift of 45Sc at room temperature decreased with increase of x, and the Knight shift of 11B did not depend on x. The absence of any B 1s and the small Knight shift of 11B in ScRh 3B x indicate that the charge density of B is independent of the concentration of B. The Knight shift of 45Sc indicates that the partial density of states of Sc 4s decreases smoothly with x. The Knight shift and no dependence of FWHM of Sc 2p 3/2 indicate that the charge on Sc atoms has a unique value and for each x, irrespective of whether the nearest B sites are occupied or empty. The results of the two spectroscopies are compared with ab initio band calculations of the electronic structures in ScRh 3 and ScRh 3B. The theoretical valence band X-ray photoelectron spectra agree well with the experimental ones. The calculation indicated that the addition of B to ScRh 3 induces charge transfer not only from Sc to Rh but B to Rh. The Knight shift of 45Sc in NMR is well described with the change of partial density of states of Sc levels.