SovietRxiv · Open Access in English
Rediscovering the Soviet scientific archive, in English
25357 full-text translations 14926 English PDFs 22539 abstracts
Showing 50 of 4600 papers in Chemistry
The paper addresses the synthesis of large, strong polycrystalline formations of cubic boron nitride, a material valued for diamond-like hardness, high thermal stability, and chemical inertness toward iron. Motivated by earlier production of polycrystalline diamond aggregates, the authors sought pre…
This paper reports the synthesis and crystallographic characterization of new oxide garnets containing hexavalent tellurium, with attention to substitution of divalent ions by mono- and trivalent ions in garnet structural sites. Ceramic samples were prepared by heating carbonate and oxide mixtures i…
The paper treats the reconstruction of a centrosymmetric basic system from its vector system for crystals in the Fedorov group P overline 1, extending a previously proposed procedure for acentric crystals. Under the condition that no additional vector coincidences raise peak multiplicity above two, …
The paper determines the crystal structure of the mineral calciborite and evaluates its chemical formula in light of earlier analytical and synthetic-polymorph data. Using Weissenberg X-ray diffraction intensities, Patterson methods, electron-density syntheses, and least-squares refinement in the or…
The paper reports a single-crystal X-ray determination of the crystal structure of sodium zirconium oxyorthosilicate, Na2ZrSiO5, a compound of interest in alkali zirconia silica systems used for heat-resistant materials and adsorbents. Using Patterson and electron-density syntheses followed by least…
The study reports the synthesis and characterization of rare-earth oxytungstate chlorides of composition Ln3WO6Cl3, where Ln is Ce, Pr, or Nd, extending a previously identified group of tungstate chlorides containing chlorine anions. Single crystals were obtained by hydrothermal crystallization in c…
The paper determines the crystal structure of the Khibiny mineral phenaksite, a potassium, sodium, and iron silicate, and refines its formula as KNaFe[Si4O10]. Using Weissenberg X-ray diffraction data, Patterson analysis, multiple-peak methods, electron-density syntheses, and least-squares refinemen…
The crystal structure of the double fluoride BaTm2F8, formed in the BaF2, TmF3 system, was determined from single crystal X-ray diffraction data because no structural analogues were known. Using heavy atom methods, Patterson and electron density projections, and least squares refinement, the authors…
This paper examines the role of cementite, Fe3C, in diamond synthesis in the iron, graphite system under high pressure and temperature. The authors compare thermodynamic considerations with experiments at about 60 kbar and 1500 to 1600 degrees, including tests on iron, graphite mixtures of varied co…
This study examines the nature of chemical bonding in vanadyl complexes incorporated into oxide glasses, using electron paramagnetic resonance and electronic absorption spectra for phosphate, silicate, and borate systems containing vanadium. Interpreting the spectral parameters within molecular-orbi…
The paper reports the crystal structure determination of a new scheelite-related modification, Nd2WO6, using x-ray diffraction data from twinned plate crystals synthesized hydrothermally and from chloride melts. The structure is described mainly in space group I2/c, with a cell related to scheelite …
This paper examines apatite-like phases formed in the MeO, Nd2O3, SiO2 systems, where Me is Mg, Ca, or Ba, through heterovalent substitution of Nd3+ by divalent cations. Samples with nominal compositions of the type Me x Nd5-x(SiO4)3Oy were synthesized by prolonged firing at 1450 degrees C and analy…
The crystal structure of paraoxyacetophenone was investigated by X-ray diffraction in connection with comparisons to benzophenone, which has the same space group but different piezoelectric behavior. Unit-cell parameters, density measurements, and Weissenberg intensity data showed that the orthorhom…
This study examines glasses in the RO, Al2O3, B2O3, SiO2 system, where RO is CaO, MgO, SrO, BaO, ZnO, CdO, or PbO, with attention to crystallization behavior and structural changes. Differential thermal analysis, forced crystallization, X-ray phase analysis, and infrared spectroscopy were used to co…
The crystal structure of isothiocyanato-dinitro-(ethylenediamine)-amminecobalt(III) was determined to verify the ligand configuration inferred from chemical substitution reactions and the trans influence. Monoclinic crystals in space group P21/c were studied by X-ray diffraction using Patterson and …
This study examines the high pressure polymorphic transformation of silver chloride and the crystal structure of the AgCl II phase, addressing discrepancies between earlier volumetric and X-ray interpretations. X-ray diffraction patterns were obtained for AgCl over 40 to 115 kbar, and for AgCl mixed…
The paper determines the crystal structure of the monoclinic modification of potassium zirconium diorthosilicate, K2ZrSi2O7, using X-ray diffraction data, Patterson analysis, electron-density syntheses, and least-squares refinement. The structure has space group P21/b, with Zr in nearly regular octa…
The paper reports an X-ray crystallographic determination of hydrothermally synthesized sodium titanogermanate, Na2(TiO)[GeO4], in order to assess its structural relation to analogous silicates and the role of germanium in tetrahedral coordination. Using three-dimensional Patterson analysis and refi…
The paper determines the crystal structure of landauite from the Burpala massif using X-ray diffraction data, Patterson projections, electron-density maps, and least-squares refinement. It evaluates alternative chemical and symmetry models and finds that the centrosymmetric space group A2/a with the…
This paper proposes sensitized photolysis on semiconductor surfaces as a basis for long-wavelength photography, extending the two-stage mechanism of silver-halide latent-image formation to systems where adsorbed metal ions are reduced by photoexcited carriers. The authors examine photoreduction of s…
This crystallographic note proves a theorem on recovering an acentric basic system of points in the Fedorov group P1 from its vector system when the vector system contains a peak of multiplicity n arising from n equal point-pair vectors, under restrictions excluding higher accidental coincidences. U…
The study determines the crystal structure of the anhydrous plate form of copper DL-alpha-alaninate, a compound unsuitable for conventional X-ray analysis because it forms very thin, brittle plates. Electron diffraction patterns from textured polycrystalline specimens and spot patterns were indexed …
This paper examines features of Patterson syntheses that are directly connected with symmetry elements in crystal structures, extending earlier use of triples of Patterson peaks beyond centrosymmetric cases. The authors represent the basic atomic system and its Patterson vector system as systems of …
The crystal structures of ammonium bis(dimethylglyoximato)bis(selenocyanato)cobaltate(III) trihydrate and the corresponding thiocyanato compound are determined and compared. X-ray diffraction data, Patterson and electron-density maps, and least-squares refinement establish monoclinic P21/n cells wit…
The paper examines the limiting case of separating a crystallographic basic point system from its vector system when the selected vector peak has multiplicity two in the Fedorov group P1. It argues that when two pairs of points in the basic system define equal vectors, the corresponding vector syste…
This study applies the solubility method to examine isomorphous substitution in yttrium aluminum and yttrium gallium garnets containing neodymium, using a PbF2, PbO, and B2O3 melt as solvent at 1100 °C. Solubility isotherms were obtained for systems involving Y3Al5O12, Y3Ga5O12, Nd3Al5O12, and Nd3Ga…
This study examines how the structural nature of initial carbon materials affects catalytic diamond synthesis under high pressure and temperature. Using carbyne, graphitizing and non-graphitizing polymer cokes, and several carbon blacks, the authors compare diamond yields, electrical-resistance kine…
The crystal structure of tetracalcium trihydrotrialuminate, formed in hydrothermal synthesis and during hardening of alumina cements at elevated temperatures, is determined from single-crystal X-ray diffraction data. Transparent rhombic crystals were examined by diffractometry, yielding an orthorhom…
The paper examines the short-range structure of liquid nickel and iron slightly above their melting points using X-ray structural analysis of radiation scattered from the free surface of the melts. Intensity curves and atomic distribution functions were obtained under controlled helium atmosphere, w…
The paper determines the crystal structure of metastable calcium chlororthosilicate, Ca3[SiO4]Cl2, a phase relevant to chloride interactions in Portland cement clinker and to reinforcement corrosion after hydration. Single-crystal X-ray data from protected, rapidly degrading crystals were analyzed u…
This paper examines sectorial growth in synthetic cubic boron nitride crystals produced under high-pressure and high-temperature conditions designed to create a mobile saturated gaseous phase in the reaction volume. Platy and tabular crystals were studied by stereoscopic, polarizing, and metallograp…
This study investigates the origin of green, brown, and blue coloration in synthetic quartz grown from carbonate solutions with iron or cobalt additives. Using electron paramagnetic resonance, optical absorption spectroscopy, annealing experiments, and electron microscopy, the authors compare the be…
This paper examines the conditions governing isomorphous substitution of atoms in solid solutions formed by intermetallic compounds. It argues that, beyond similarities of chemical nature, crystal structure, and atomic size, a more fundamental criterion is the mutual chemical indifference of atoms o…
This paper examines the structured visible and near ultraviolet absorption spectrum of cesium uranyl chloride crystals at 77 K, addressing competing interpretations of the band structure in uranyl chloride compounds. Absorption spectra were recorded in linearly polarized light for selected crystal o…
The paper reports the laboratory synthesis of polycrystalline diamond formations of the carbonado type, distinguished from previously synthesized ballas by a much finer grained structure and an X-ray diffraction halo resembling that of natural carbonado. The authors compare the microstructures of na…
The paper reports the synthesis and crystal-structure determination of the scandium sodium diorthosilicate Na3Sc[Si2O7], obtained as transparent rhombic single crystals in the Na2O, Sc2O3, SiO2, H2O system. X-ray diffraction, Patterson and electron-density syntheses, and least-squares refinement in …
The paper reports an independent X-ray refinement of the crystal structure of ramsaite, Na2Ti2Si2O9, undertaken to verify and improve an earlier closest-packing-based model. Single-crystal Weissenberg data and three-dimensional least-squares refinement in space group Pnca gave atomic coordinates for…
This paper develops an alternative theory of the electronic structure of cyclic molecules in which strong Coulomb repulsion makes tunneling of one pi electron through another negligible, producing a one-dimensional Wigner chain that undergoes hindered rotation relative to the molecular framework. Th…
The paper develops a statistical mechanical treatment of weakly nonideal partially ionized hydrogen consisting of atoms, protons, and electrons under Debye screened Coulomb interactions. Using a grand canonical ensemble expressed in terms of physical groups, it separates bound and free proton electr…
This study reports photoelectric Raman measurements for tetramethylsilane and a series of methylchlorosilanes, determining fundamental frequencies, peak and integral intensities, half-widths, depolarization degrees, corrected scattering coefficients, and polarizability-derivative tensor invariants. …
The paper investigates charge states of krypton atoms produced by electron capture of radioactive rubidium in rubidium fluoride, chloride, and bromide matrices, using the Mössbauer emission spectra of the 9.3 keV transition in krypton-83. Resonance spectra were measured at selected temperatures and …
Ytterbium films condensed onto liquid-helium-cooled glass substrates were studied through temperature-dependent electrical resistance measurements during controlled warming. Seventeen films with thicknesses from 240 to 18000 Å showed a sharp resistance decrease near 14 K for layers thinner than abou…
The paper reports a single-crystal X-ray determination of the structure of sodium dichromate dihydrate, Na2Cr2O7·2H2O, using three-dimensional Patterson and electron-density syntheses followed by least-squares refinement. The study revises the symmetry to the hemimorphic space group P21, locates 77 …
This study determines the crystal structure of uralborite, a hydrous calcium metaborate, using X-ray diffraction data from Weissenberg photographs and refinement by least squares in the monoclinic space group P21/n. The analysis confirms the composition Ca2[B4O4(OH)8], distinguishes hydroxyl groups …
This study examines whether vibrational frequencies of ammonium cations can be identified in the fluorescence spectra of double uranyl salts through isotopic substitution. Infrared absorption and liquid nitrogen luminescence spectra were measured for ammonium uranyl chloride and ammonium uranyl sulf…
