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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.

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The heat capacity Cp, thermal diffusivity χT, and lattice thermal conductivity κlatt of ceramic solid solutions of sesquisulfides Gd3‐xVGd,xS4 (0 < x < 0.33) in the temperature range 300‐700 K has been studied. Changing the real structure, namely the concentrations of vacancies (NV) and deformation (NDc) centers of polycrystals, significantly decreases κlatt. A deviation of composition from the stoichiometry 2:3 is accompanied by an increase in the specific area of the crystallite boundaries per unit volume, and, hence, the concentration of deformation centers DC increases. This observation was confirmed by examining the short‐range order disturbance of the lattice and symmetry environment of the Gd3+ and S2− environment by Raman spectroscopy and the magnetic susceptibility Faraday method. Therefore the thermal diffusivity of gadolinium sesquisulfide is reduced because of the mean free path of phonons decrease. As a result, the thermal conductivity of the polycrystalline samples is reduced by 10%.