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[en] Mixed indium alkali metal selenites Msub(x)sup(1)In(SeOsub(3)Hsub(1-x)SeOsub(3))xnHsub(2)O (M1=Rb, x=0.3-0.8) are prepared under hydrothermal conditions for the first time. They are regarded as compounds of variable composition in the structure of which the significant role is played by the system of hydrogen bonds. The existence of In mixed selenites of the Nasub(2)In(SeOsub(3))sub(2.5) and RbInH(SeOsub(3))sub(2.5)xHsub(2)O compositions is found, which did not occur in the case of Al and Ga. The tendency to form mixed selenites increases in the Al-Ga-In series, that is connected with the increase of In complexing ability during interactions with oxygen-bearing acidoligands. Mixed selenites in the Li→Cs series of alkali metals are more easily formed with Rb and Cs (weakly polarizing cations)
[en] Highlights: •Charge trapping centers in TlGaSe2 were investigated using thermally stimulated current (TSC). •Temperature dependent frequency factor and capture cross section are computed. •Both TSC and the dark currents are measured in direction perpendicular to the layers. . -- Abstract: Charge trapping centers in TlGaSe2 single crystals were investigated by the use of thermally stimulated current (TSC) technique. The measurements of TSC spectra in the temperature range from 90 K to 300 K were performed at a constant heating rate. The measurements showed that there are several trapping levels associated with the complex structure of overlapping peaks in the spectrum. The TSC spectra are dominated by two levels appeared at 204.1 K and 220.1 K. The experimental results indicate that the traps in TlGaSe2 associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters, such as the energy depth, temperature dependent frequency factor and capture cross section together with the concentrations of the corresponding eight discrete levels, are computed. These centers all having high capture cross sections are found to be at the energies of 0.20 eV, 0.22 eV, 0.26 eV, 0.31 eV, 0.35 eV, 0.49 eV, 0.60 eV and 0.67 eV with low concentrations of 8.9 × 1013, 7.8 × 1013, 1.1 × 1014, 3.5 × 1013, 4.4 × 1013, 3.8 × 1013, 9.8 × 1014 and 8.8 × 1014 cm−3, respectively
[en] Certain results of the study of deintercalation of transition metal dichalcogendie intercallates under controlled conditions of vapour-gas phase are considered, using as an example model system Zn-2H-NbSe2. It is ascertained that the process of deintercalation is accompanied by autointercalation with the formation of quilibrium biintercalates ZnxNb1+ySe2
[en] The kinetics of dehydration of Al2(SeO3)3·6H2O, Ga2(SeO3)3·6H2O and In2(SeO3)3·6H2O were studied under non-isothermal heating on a derivatograph. The method of Coats-Redfern was used with different kinetics models. The values of the kinetics parameters characterizing the process were calculated. The dependencies observed were interpreted according to the generalized perturbation theory of chemical reactivity. Kinetic compensation effect was found
[en] Atomic-molecular mechanisms of crystal growth can be modeled based on crystallochemical information using cellular automata (a particular case of finite deterministic automata). In particular, the formation of heteropolyhedral layered complexes in uranyl selenates can be modeled applying a one-dimensional three-colored cellular automaton. The use of the theory of calculations (in particular, the theory of automata) in crystallography allows one to interpret crystal growth as a computational process (the realization of an algorithm or program with a finite number of steps).