Crystal structure and XPS analysis of in-doped β-Zn4Sb3

β-Zn4Sb3 is a promising candidate thermoelectric material with extraordinary low lattice thermal conductivity and high dimensionless figure of merit. In the paper, X-ray diffraction (XRD) patterns and X-ray photoelectron spectra (XPS) of In-doped β-Zn4Sb3 compounds with nominal composition Zn4Sb3-mInm (0≤m≤0.18) were investigated to reveal the effect of indium doping on crystal structure and binding characteristics. The Rietveld refinement based on the XRD data indicates that the indium impurity preferentially occupies the 12c Sb(2) site in Zn4Sb3-mInm. The lattice parameter a increases and c decreases with the increasing m, accompanying with the lattice distortion and the bond length and angle modification. Indium doping enhances the occupancies of Zn atoms at the 36f Zn(1) and interstitial Zn sites, whereas the total occupancy of Sb and In atoms maintains constant. XPS analysis shows that the valence of Sb decreases and that of Zn increases with increasing the indium doping in Zn4Sb3-mInm. This implies ...