The effect of gamma irradiation on the dielectric properties and ac conductivity of a TlInS2 single crystal with a layered structure has been investigated in the frequency range from 5 × 104 to 3.5 ×

We have constructed the T-x phase diagram of the TlGaS₂-TlFeS₂ system (simple eutectic system, eutectic at 80 mol % TlFeS₂ with a melting point of 953 K). The system contains limited series of monoclinic solid solutions based on the ternary end-members. At an annealing temperature of 933 K, the TlGaS₂-based solid solution extends to 5 mol % TlFeS₂ and the TlFeS₂-based solid solution extends to ≅10 mol % TlGaS₂. We have examined the effect of partial iron substitution for gallium on the optical properties of melt-grown single crystals of the TlGaS₂-based solid solutions and determined their band gap as a function of temperature and Fe concentration.

The real and imaginary parts of the complex dielectric permittivity, the dielectric loss tangent, and ac conductivity of crystals of TlInSe₂-TlGaTe₂ solid solutions have been measured as functions of frequency in the range 50 kHz to 35 MHz, and the ΔG _T ⁰ and heat capacity of the (TlInSe₂)_{1 − x} (TlGaTe₂) _x solid solutions have been determined as functions of temperature. The results demonstrate that, over the entire composition range, the measured physical properties of the solid solutions correlate with their composition.

Samples in the Li₂O–B₂O₃–Yb₂O₃ system were synthesized and studied by differential thermal analysis, X-ray powder diffraction analysis, and thermodynamic analysis. Polythermal sections and an isothermal section of the phase diagram of this system were constructed. It was shown that the polythermal sections Li₂O ⋅ 3B₂O₃–Yb₂O₃ ⋅ B₂O₃ and Li₂O ⋅ B₂O₃–Yb₂O₃ ⋅ B₂O₃ are non-quasi-binary, and Li₂O ⋅ 2B₂O₃–Yb₂O₃ ⋅ B₂O₃ and Li₆Yb(BO₃)₃–YbBO₃ are quasi-binary. The isothermal section in the Li₂O–B₂O₃–Yb₂O₃ system at 25°C has 15 stable tie lines, which divide the system into 14 triangles of coexisting phases. The compounds 6Li₂O ⋅ Yb₂O₃ ⋅ 3B₂O₃ and 3Li₂O ⋅ 2Yb₂O₃ ⋅ 3B₂O₃ were synthesized, and their physicochemical properties were studied. The temperature dependences of the electrical conductivity of polycrystalline samples in the Li₂O–B₂O₃–Yb₂O₃ system at direct current were investigated. The activation energies of the conduction of semiconducting samples were determined. It was observed that, with adding Yb₂O₃ (x = 0–0.02), the electrical conductivity of samples of the composition (1 – x)Li₂O ⋅ 3B₂O₃–xYb₂O₃ ⋅ B₂O₃ decreases, and the activation energy increases from 0.87 to 0.94 eV.

The results of studies by the density functional theory (DFT) method of the density of the electronic states (DOS) of supercells of the interface of defective graphene/Ge are presented. The regularities of the change in DOS in the series graphene/Ge → graphene + vacancy/Ge (GPV) are studied. The features of the distribution of the density of electronic states at the ordered vacancy–graphene/Ge interface are discussed. The nature of the bond between graphene and germanium and the adsorption properties of the GPV–Ge system are studied based on the DFT calculations and physicochemical modeling.