Vol 68, No 2 (2023)

Search for chlorine-conducting solid electrolytes with a high ionic conductivity σ_293K at room temperature (293 K) is based on the analysis of temperature measurements of the electrical conductivity σ(T) of simple and complex compounds, solid solutions, composites, and glasses. A comparison of the thermal stability of chlorides is based on the analysis of the dependences σ(T) in cyclic heating–cooling measurements and the physicochemical data. Maximum σ_{293 K} values were found for the solid solutions (3 × 10⁻⁵ S/cm) and (1 × 10⁻⁴ S/cm). Promising directions of search for chlorine-ion solid electrolytes for chemical current sources and chlorine sensors operating at room temperature are the method of crystallochemical heterovalent substitutions and implementation of the vacancy mechanism of electrical conductivity in crystal structures of the cotunnite (PbCl₂) and fluorite (CaF₂) types. The parameters of the ionic conductivity of cotunnite and fluorite crystals of chlorides and fluorides are analyzed.

The results of studying the specific features of the growth of zinc oxide films formed on sapphire substrates by magnetron sputtering in an inhomogeneous electric field are presented. The films have been analyzed by high-resolution X-ray diffractometry, pole figure technique, and electron microscopy. A sequence of changes in the lateral structure with an increase in the film thickness, which depends also on the local potential, is revealed. Thus, regions with a higher surface potential correspond to the ZnOá10 0ñ(0001)||Al2O3á11 0ñ(0001) epitaxial ratio with the least lattice mismatch.

A new scheme for the numerical solution of Takagi–Taupin equations, which makes it possible to simulate the effect of synchrotron radiation diffraction in crystals of arbitrary structure, is described in detail. The new scheme is convenient to perform calculations for crystals of arbitrary shape. The rectangular coordinate system and the algorithm for calculating derivatives at half of step have proven their efficiency and are used, but the recurrence equations of this algorithm have been modified towards simplification. The boundary conditions are in no way related to the crystal boundaries. A computer program is developed, and two examples are considered for the cases of diffraction in the Laue and Bragg geometries, for which the analyticl solutions are known. The calculation results are in complete agreement with these solutions.

A ladder-wise calculation scheme has been developed for the structural complexity of heterodesmic crystal structures, with crystal interpreted as a system of contacting molecules, chains, and layers. In the last stage of ladder-wise calculation the structural complexity of the main motif is summed with the complexity of the contacts beyond the main motif in correspondence with the strong additivity rule. The application potential of the scheme is demonstrated, and the calculation results for the crystal structures of natural and synthetic arsenic sulfides are presented. The coordination of molecules and chains that is necessary for calculating the complexity of contacts beyond the main motif is determined by the method of Voronoi–Dirichlet polyhedra.

The diverse local environment of zinc ions in a ZnCl₂ solution, depending on the symmetry, ligand type, and solution concentration, has been analyzed using the data in the literature. Experimental zinc K-edge XANES spectra in a ZnCl₂ aqueous solution with a critically low concentration (10^–3 М) have been theoretically analyzed. It is shown that Zn(H₂O) complexes with Zn²⁺ ions in the octahedral coordination environment of water molecules are dominant in this solution.

Tetrabasic ethylenediaminetetraacetic acid H4L binds two molecules of monobasic amines to give the corresponding salts: ethylenediaminetetraacetates of bis(monoethanolaminium) H2L2–⋅2+H3NCH2CH2ОН, tris(hydroxymethyl)methylaminium H2L2–⋅2+H3NС(CH2ОН)3⋅3H2О, diethylaminium H2L2–⋅2+H2N(C2H5)2⋅H2О, tert-butylaminium H2L2–⋅2+H3NС(CH3)3⋅5H2О, and triethanolaminium H2L2–⋅2+HN(CH2CH2ОH)3. Dibasic hexamethylene-1,6-diamine, triethylenediamine, and tetramethylethylenediamine form the following 1 : 1 adducts: H2L2–⋅
+NH3(CH2)6NH , H2L2–⋅+NH3CH2CH2(OCH2CH2)2NH , H2L2–⋅ +HN(CH2)3NH+⋅H2О, and H2L2–⋅+H(CH3)2NCH2CH2N(CH3)2H+. The molecular structures of bis(monoethanolaminium) ethylenediaminetetraacetate and bis[tris(hydroxymethyl)methylaminium] ethylenediaminetetraacetate trihydrate were determined

The solvated complex [МоО2(L1)]4dimethylformamide (I) was synthesized. Its structure was
determined by X-ray diffraction analysis. The crystal structure is composed of the tetranuclear complexes [МоО2(L1)]4 (Ia) as the structural units lying on crystallographic twofold axes. Both crystallographically independent molybdenum atoms are in a distorted octahedral coordination environment formed by two cis-О(oxo) ligands, two N(L1) atoms of two molecules Ia in trans positions to the О(oxo) ligands, and two О(L1) atoms of one complex molecule in cis positions to О(oxo) and trans to each other. Each (L1)2– ligand is coordinated to two Мо atoms in a tetradentate tridentate-chelating (2О, N) bridging (N) mode. The average bond lengths in complex Iа are as follows: Мо–О(oxo), 1.701 Å; Мо–N(L1), 2.460 (b) and 2.214 Å (c); Мо–О(L1), 1.980 Å. The О(oxo)–МоО–(oxo) bond angle is 105.6°. The ordered dimethylformamide molecule is located in a narrow channel in the structure. The strongly disordered (non-located) solvent molecules (methanol/dimethylformamide/water) occupy wide channels in the structure of I.

Molecular dynamics simulations were performed for wild-type purine nucleoside phosphorylase in complexes with two substrates (adenosine and guanosine). The MD simulations were also performed for the mutant form of the enzyme with the same substrates. The free energy changes upon the formation of the complexes were evaluated from the molecular dynamics trajectories by the MM-GBSA method.

Preliminary comparative studies of the photoluminescent properties of two-dimensional ZnO nanostructures with morphology of nanowalls, nanosheets, and nanocombs, fabricated by gas-transport synthesis, have been performed. All structures exhibited near-band-edge (NBE) UV emission of the same order of intensity. Unlike nanocombs, whose spectrum contains a comparatively strong green luminescence band, nanowalls and nanosheets are characterized by a large ratio of the UV and visible components. This distinction is presumably due to the difference in the mechanisms of structure formation: nanowalls and nanosheets are formed according to the vapor–liquid–solid mechanism, whereas nanocombs grow according to the vapor–solid mechanism

The results of comprehensive studies of structural and phase transformations in
(K0.43(NH4)0.57)3H(SO4)2 superprotonic crystals under the influence of atmospheric moisture are presented. The real structure, composition, and thickness of the modified surface layers have been analyzed using scanning electron microscopy and X-ray microscopy. The local characteristics of nanostructures, formed on the freshly cleaved (001) crystal surface subjected to the electrostatic effect, have been investigated by conductive atomic force microscopy. A correlation has been established between the time changes in the structure, composition, and magnitude of the electrostatic potential of the crystal surface. The results are considered in the context of evaluation of the chemical stability of the samples and searching for the ways to optimize the compositions and functional properties of superprotonic compounds.

Nanostructured submicron calcium carbonate particles with sizes of 500 ± 90 and 172 ± 75 nm have been synthesized by mass crystallization in aqueous solutions with addition of glycerol, as well as a mixture of polyethylene glycol, polysorbate, and a cellular medium. CaCO3 : Si : Fe nanoparticles 65 ± 15 nm in size have been obtained by template synthesis in pores of silica particles. The crystal structure and polymorphism of these particles are studied, and the influence of the size and structure of particles on the efficiency of their loading with a chemotherapy agent , as well as its release under model conditions at different рН, is determined.

Gallium nanostructures have been obtained on silicon substrates by thermal evaporation in an argon atmosphere. The sizes, density, and shape of Ga particles have been determined by computer processing of electron SEM-images. The condensation of Ga on Si substrates for 10, 15, and 20 s ensured the formation of particles of several types: spherical, triangular, square, and in the form of rods and polyhedrons. The increase in the Ga condensation time to 20 s led to the increase in the density of spherical nanoparticles by 41%.

The specific features of application of a low-energy atomic-force microscope (AFM) for studying the dynamic process of face growth in terms of the fluctuation model of crystal growth are discussed. It is shown that the probe interaction with an area of growing crystal surface on the time scale characteristic of a sequence of free energy fluctuations is a limiting factor for constructing an image of growing face surface.Agreement between the phenomenological and quantum (according to the uncertainty relation) descriptions of the effect of limiting magnification for a growing crystal face in an AGM is demonstrated. Specific features of detecting a growth stage on a crystal face using a transmission/scanning high-resolution electron microscope in a gas medium are also discussed. The effect of ultimate magnification when observing crystal growth in an АСМ is a basis for discussing the concept of the transient state of matter in the topochemical reaction of crystal growth and the phenomenon of building particle.