ELECTRONIC-STRUCTURE OF THE BAV1-XTIXS3 SYSTEM AS STUDIED BY PHOTOELECTRON-SPECTROSCOPY

X-ray and ultraviolet photoelectron-spectroscopic (XPS and UPS) studies to investigate the core levels and valence-band spectra of BaV(1-x)Ti(x)S3, With x =0 and 0.2, is reported. The XPS results indicate that the valence of V as well as Ti is not 4 as would be expected nominally, but between 3 and 4. Essentially no difference of the core-level binding energies was observed between the two samples. The valence-band spectra exhibit three peak features at about 1, 2.5, and 4 eV. From the enhancement of the peak at 1 eV by the He II photon, it is concluded that the V 3d orbitals are strongly incorporated in this peak that is close to the Fermi level. It is shown that the bond-valence-sum method can be useful as a quantitative tool for discussion of XPS results. The possibility of using the bond-valence-sum calculation for discussions on the transport properties of the system is also shown.