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We report the preparation of SmS@Y2O2S and Y2O2S@SmS ceramics with a core–shell nanostructure via 1123-K sulfidation of rare-earth oxides prepared by the sol–gel method, involving precipitation from starting metal nitrate solutions with NH4OH as a precipitant, followed by annealing of the resultant sulfide phases in an induction furnace at 1473 K. Using X-ray diffraction and scanning electron microscopy data, we have evaluated the average crystallite size in the materials and examined the morphology of the constituent phases in them. In addition, the short-range order in the coexisting nanostructures has been analyzed in detail using Raman spectroscopy and X-ray photoelectron spectroscopy data. [ABSTRACT FROM AUTHOR]

The comprehensive study of the electronic density distribution of CuCr0.99Ln0.01S2 (Ln = La, Ce) solid solutions was carried out using both X-ray photoelectron and emission spectroscopy. It was found that cationic substitution of chromium with lanthanum or cerium atoms does not significantly affect the atomic charges of the matrix elements (Cu, Cr, S) in the lanthanide-doped solid solutions. The copper atoms in the composition of CuCrS2-matrix and the lanthanide-doped solid solutions were found to be in the monovalent state. The chromium and lanthanide atoms were found to be in the trivalent state. This fact indicates the isovalent cationic substitution character. The sulfur atoms were found to be in the divalent state. The near-surface layers contain the additional oxidation forms of sulfur (S0, S4+, S6+) and copper (Cu2+) atoms. The detailed analysis of the valence band structure using DFT calculations has shown that partial DOS distribution character of the matrix elements is preserved after the cationic substitution. The experimental valence band spectra structure of CuCrS2-matrix and CuCr0.99Ln0.01S2 is determined by the occupied copper d-states contribution. The contribution of the lanthanide states in the valence band structure is lower in comparison with those for the matrix elements. The major contribution of the lanthanide states was found to be mainly localized near the conduction band bottom. [ABSTRACT FROM AUTHOR]