The activation energy values of oxygen ion diffusion in yttria-stabilized zirconia (one of the most promising solid electrolytes for fuel cell technologies), estimated in molecular dynamics studies with the classical Buckingham potential, turn out to be significantly lower than experimental ones. A possible reason is the incorrect calibration of the potential, the parameters of which were selected earlier using simple model systems. In this paper, three sets of potential parameters have been developed based on the calibration of the interatomic potential based on the results of periodic DFT calculation in an extended system. The results of molecular dynamic modeling using the developed parameter sets reproduce much better the experimental values of activation energies with a variation of the molar fraction of the dopant in a solid electrolyte.

It was for the first time that the heat capacity of β-pyrochlore complex oxides RbTe1.5W0.5O6 and Rb0.95Nb1.375Mo0.625O5.79 was investigated by adiabatic vacuum calorimetry and differential scanning calorimetry in the temperature range T = (6–640) K. The obtained experimental data were used to calculate the standard thermodynamic functions: heat capacity C_p^o , enthalpy [H°(T)−H°(0)], absolute entropy [S°(T)], and Gibbs free energy [G°(T)−H°(0)] for the range from T → 0 to 640 K. The low-temperature (T < 50 K) heat capacity trends were analyzed in terms of the multifractal model, and a chain–layered structure topology of the studied compounds was established.

The review summarizes studies on modification of fish collagen and pectin to obtain the branched and three-dimensional structures. They are biodegradable and biocompatible sealants prepared via radical graft copolymerization under photocatalysis in the presence of a RbTe1.5W0.5O6 complex oxide of a β-pyrochlore structure, including the variation of composition of a initial reaction mixture, and via the isolation stage by introduction of known modification additives.

The structure of the ideal α-pyrochlore with stoichiometry A2M2X6X′ (A—large low-charge cation of alkali, alkaline earth, or rare earth elements), M—a small high-charge cation capable of octahedral coordination (p- or d-elements), X—ions O2– and OH–, F–, or molecules H2O, X′—ions weakly bound to M) has a cubic symmetry with the space group $$Fd\overline{3}m$$ (Z = 8). This Chapter is devoted to consideration of the structural features and properties of α-pyrochlore oxides.

The antimicrobial activity of fine particles of submicron size WO3 and RbTe1.5W0.5O6 in relation to the bacteria Escherichia coli and Staphylococcus aureus is studied. It is found that all the studied compounds cause a decrease in the survival of bacteria both in the dark and in the light. It is shown that a decrease in the size of RbTe(1.5)W(0.)5O(6) particles enhances their antimicrobial effect. The action of light (source power 30 and 50 W) enhances the antimicrobial activity of the compounds under study, especially for RbTe1.5W0.5O6 with a smaller particle size, which indicates their photocatalytic activity. With an increase in the duration of exposure, the antimicrobial effect of the studied compounds increases. The ambiguity of the effect of light sources of different power on the bacteria is noted, which may be due to their physiological and biochemical characteristics.

New Dion-Jacobson type layered perovskite compounds A'Ln2Ti2NbO10 (A' = Rb, H; Ln = Pr, Nd) were synthesized for the first time. The phase and chemical purity of the compounds were proved by X-ray diffraction (XRD) and EDX. Compounds RbPr2Ti2NbO10 and RbNd2Ti2NbO10 were synthesized using solid-state reactions, whereas HPr2Ti2NbO10.1.5H2O and HNd2Ti2NbO10.2H2O were obtained from Rb-containing phases by ionexchange reactions. Crystal structures of RbPr2Ti2NbO10 (P4/mmm, a = 0.38223 (1) nm, c = 1.51485 (8) nm, Rwp = 3.87%) and RbNd2Ti2NbO10 (P4/mmm, a = 0.38153 (1) nm, c = 1.51200 (6) nm, Rwp = 3.62%) were refined using the Rietveld method. The distortions of polyhedrons in the structures were studied in detail. The thermal behavior of compounds was established using DTA. The ion-exchange products were found to be metastable hydrates. Optical band gap, valence band edge and conduction band edge potentials of obtained compounds were calculated from diffuse reflectance spectroscopy data. Photocatalytic experiment of methylene blue degradation under ultraviolet (UV) light was conducted with ground synthesized compounds. The particle size distributions were measured by laser diffraction before and after grinding. RbNd2Ti2NbO10 showed the highest photocatalytic activity, while HPr2Ti2NbO10.1.5H2O and HNd2Ti2NbO10.2H2O showed none.

The antifungal activity of fine submicron-size particles of WO3 and RbTe1.5W0.5O6 against the spores and vegetative mycelium of Aspergillus niger and Penicillium chrysogenum fungi is studied. It is found that the studied compounds WO3 and RbTe1.5W0.5O6 caused a decrease in the survival rate of microorganisms in the dark. Antifungal activity increased against both the spores and vegetative mycelium of fungi under light exposure with a power of 30 and 50 W with a radiation-flux density of 325.5 and 524 W/m(2), respectively, which indicates their photocatalytic activity. It is noted that the antifungal activity of RbTe1.5W0.5O6 both under light and dark conditions on the spores and vegetative mycelium of fungi is higher compared to WO3. The antifungal effect of the compounds under study increased with an increase in the duration of exposure and the intensity of illumination.

The synthesis of polymethyl methacrylate – collagen graft copolymer was carried out upon initiation of the process by radicals formed upon irradiation of the complex oxide RbTe1.5W0.5O6 with visible light (λ = 400-700 nm) at a temperature of 250C. The characteristics of the new polymer material were obtained by the methods of elemental and physicochemical analyzes.

A new series of Dion-Jacobson layered perovskite compounds A’LnNaNb3O10 (A’ = Cs, Rb, H; Ln = Nd, Pr) was synthesized for the first time. Phase and chemical purity of compounds were proved using XRD, SEM, and EDX. Compounds RbNdNaNb3O10, RbPrNaNb3O10, CsNdNaNb3O10 and CsPrNaNb3O10 were synthesized using solid-state reaction, whereas HNdNaNb3O10, HPrNaNb3O10 were obtained by ion-exchange reaction. Crystal structures of solid-state reaction products were refined using the Rietveld method. The plausibility of obtained crystal structures was studied using the bond valence sum (BVS) method. The thermal behavior of compounds was established using DTA. Ion-exchange products were found to be metastable hydrates. The presence of the crystallization water was confirmed by DTA and IR spectroscopy. Optical band gap, electronegativity, valence band (EVB), and conduction band (ECB) potentials of obtained compounds were calculated from diffuse reflectance spectroscopy data. A previously proposed correlation between band gap and structural distortions was confirmed.

Firstly in the present research, the heat capacity C-p,m(o) = f(T) of crystalline caesium niobium molybdenum oxide CsNbMoO6 was measured in the range of T = (6 and 340) K by the precise adiabatic vacuum calorimeter. The phase purity and composition homogeneity of prepared sample have been confirmed by X-ray diffraction analysis and X-ray microanalysis. The standard thermodynamic functions (p(o) = 0.1 MPa) of CsNbMoO6, namely C-p,m(o) Delta H-T(0)m(o), Delta S-T(0)m(o) and Delta(T)(0)G(m)(o), were calculated using the obtained experimental data from T -> 0 to 340 K. The low-temperature (T < 50 K) heat capacity dependence was analyzed on the basis of the Debye heat capacity theory of solids and its multifractal model, so the characteristic temperature and the fractal dimension were determined, and chain-layered structure topology of the studied compound was established. The standard thermodynamic functions of crystalline CsNbMoO6 formation at T = 298.15 K were calculated. (C) 2021 Elsevier Ltd.

Two lead-containing compounds of the Aurivillus family: PbBi2Nb2O9 and PbBi3Ti2NbO12 were synthesized using a conventional high-temperature solid-state (ss) method and ion-exchange (ie) method. The phase and chemical purity of synthesized compounds were confirmed by XRD and EDX, respectively. The second harmonic generation experiment confirmed that all synthesized compounds have a non-centrosymmetric crystal structure. Rietveld refinement of samples prepared by different methods confirmed that ion-exchange and solid-state products share the same crystal structures; however, indirect evidence for different distributions of Pb/Bi between crystallographic positions was observed. Phase transitions, corresponding to the Curie temperatures were detected using high-temperature XRD. Thermal expansion of ion-exchange reaction products was studied in the temperature range of 298-1273 K. The optical band gap, electronegativity, valence band (EVB), and conduction band (ECB) potentials of materials were calculated from UV-vis spectroscopy data. Both PbBi2Nb2O9 (ss) and PbBi2Nb2O9 (ie) can be used for the decomposition of organic molecules under visible light, while PbBi3Ti2NbO12 (ss) and PbBi3Ti2NbO12 (ie) can work only under UV light irradiation due to their wider band gaps.

A nontrivial and simple method for modifying the surface of anatase polymorphic particles with gold or silver nanoparticles has been developed. The method involves the UV-induced formation of Au (Ag) nanoparticles from the corresponding precursors - HAuCl4 or AgNO3 - in a solution of a stabilizing polymer - chitosan, than dispersing TiO2 particles in the resulting colloidal solution, and subsequent enzymatic destruction of chitosan. As a result, Au or Ag nanoparticles, the size of which is 5.0 +/- 0.1 nm and 22.0 +/- 0.25 nm, respectively, completely settle on the TiO2 surface. It was found that in the reactions of decomposition of methylene blue and paranitrophenol in an aqueous solution under UV irradiation, modified TiO2 is 2-2.5 times more photocatalytically active than the initial titanium dioxide. It is essential that the photocatalytic properties of TiO2 modified with Au (Ag) nanoparticles also manifest themselves under the action of visible light.

Two new isostructural mixed-valence tellurium oxides, CsTe1.625W0.375O6 (1) and RbTe1.5W0.5O6 (2), have been synthesized by solid-state reaction. The single crystals of obtained compounds have been characterized by single-crystal X-ray diffraction analysis. Both compounds have beta-pyrochlore-type structure (cubic system, space group Fd-3m, Z = 8) and the following unit cell parameters: a = 10.5437(2) angstrom in (1) and a = 10.3949(3) angstrom in (2). The structural features have been investigated, and the distortions of the building blocks [MO6] (M = Te, W) have been found. The oxidation states of tellurium have been confirmed by X-ray photoelectron spectroscopy. The thermal behavior of obtained compounds has been studied.

The new ternary compounds Na1.5Te2Mo0.5O6.25 and K-6(Te94+Te6+)Mo6O42 have been revealed by the study of the phase relation in the systems Na2O-TeO2-MoO3 and K2O-TeO2-MoO3. The structure of the compounds has been investigated by X-ray Single-Crystal Analysis. The Na1.5Te2Mo0.5O6.25 compound belongs to anti-glass tellurium phase with fluorite-type structure and space group Fm3 m, Z = 1, a = 5.4087 angstrom, where the oxygen atoms are strongly disordered near the 8a site. The K-6(Te94+Te6+)Mo6O42 mixed-valence tellurium compound possesses trigonal space group P3, Z = 1, a = 12.0074 angstrom, c = 7.8979 angstrom. The K-6(Te94+Te6+)Mo6O42 structure contains rare units of two [TeO6] octahedron sharing three common oxygen. The decomposition temperatures are 378 degrees C and 410 degrees C for Na1.5Te2Mo0.5O6.25 and K-6(Te94+Te6+)Mo6O42, respectively.

Two new isostructural mixed-valent tellurium oxides, CsTeMoO6 (1) and RbTe1.25Mo0.75O6(2), have been synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction and thermal analysis. Both compounds have pyrochlore-type structure with cubic space group Fd (3) over barm, Z = 8 and the following unit cell parameters: a = 10.5892(5) angstrom in CsTeMoO6 and a = 10.4421(2) angstrom in RbTe1.25Mo0.75O6. A small part of the oxygen atoms shifts from the special position 48f to the general crystallographic position 192i, because the Te4+ ion is too large for the regular pyrochlore-structure framework and causes local distortions. The thermal instability of the CsTeMoO6 and RbTe1.25Mo0.75O6 phases was found at the 449-521 degrees C and 381-466 degrees C temperatures ranges, respectively.