Electronic structure and chemical bonding of phosphorus-contained sulfides InPS 4, TI 3PS 4, and Sn 2P 2S 6

Abstract

The electronic structure of phosphorus-contained sulfides InPS 4, Tl 3PS 4, and Sn 2P 2S 6 was investigated experimentally with X-ray spectroscopy and theoretically by quantum mechanical calculations. The partial densities of electron states calculated with the ab initio multiple scattering FEFF8 code correspond well to their experimental analogues—the X-ray K- and L 2,3-spectra of sulfur and phosphorus. The good agreement between theory and experiment was also achieved for K-absorption spectra of S and P in the investigated sulfides. In spite of the difference in the crystallographic structure of InPS 4, TI 3PS 4, and Sn 2P 2S 6 that influence the form of K-absorption spectra, the electronic structure of their valence bands are rather similar. This is due to the strong interaction of the P and S atoms, which are the nearest neighbors in the compounds studied. The electron densities of p- and s-states of phosphorus are shifted by about 3 eV to lower energies in comparison to the analogous electron states of sulfur. This is connected with the greater electro-negativity of sulfur, and is confirmed by the calculated electron charge transfer from P to S.