Effect of Ag doping on electronic structure of cluster compounds AgxMo9Se11 (x=3.4; 3.9)

The electronic structure of AgxMo9Se11 as potential material for thermoelectric applications was studied using high-energy-resolution fkuorescence-detection x-ray absorption spectroscopy (HERFD-XAS) and resonant inelastic x-ray scattering (RIXS) technique. The experiments were supported by first-principle calculations using density functional theory (DFT). The analysis of obtained spectra indicate the presence of subvalent (less than 1+) Ag in the AgxMo9Se11. The advanced HERFDXAS measurements allowed us to resolve the contribution of the electronic states at the Fermi level of AgxMo9Se11 and monitor its dependence on the x value. Comparison of the experimental data with the results of the DFT calculations suggests an importance of the Ag2-type sites with the shortest Ag-Se distance for affecting the properties of AgxMo9Se11