Synthesis and Study of Alkaline-Earth Metal Uranoborates,AI I(BUO5)2·nH2O

Previously unknown compounds A^{I I}(BUO₅)₂·nH₂O (A^{I I} = Mg, Ca, Sr, Ba; n = 0-7) were synthesized. Their structure and thermal decomposition were studied by X-ray diffraction, IR spectroscopy, and thermal analysis.     

Synthesis,Structure, and Physicochemical Properties of AI 4[UO2(CO3)3]·nH2O (AI = Li,Na, K,NH4)

Procedures for the synthesis of Li₄[UO₂(CO₃)₃]·1.5H₂O, Na₄[UO₂(CO₃)₃], K₄[UO₂(CO₃)₃], (NH₄)₄[UO₂(CO₃)₃], and K₃Na[UO₂(CO₃)₃] were optimized. The structures of these compounds and their thermolysis were studied by X-ray diffraction, precision IR spectroscopy, and thermal analysis. The standard enthalpies of formation of these compounds at 298.15 K were determined by reaction calorimetry.     

Synthesis, Structure, and Physicochemical Characteristics of Rutherfordite and Tetrasodium Uranyl Tricarbonate

The optimum procedures for synthesis of UO₂CO₃ and Na₄[UO₂(CO₃)₃] were developed. The structures of these compounds and their thermal decomposition were studied by X-ray diffraction, precision IR spectroscopy, and thermography. The standard enthalpy of formation of crystalline Na₄[UO₂(CO₃)₃] at 298.16 K was determined to be -4010.0±8.0 kJ mol^{- 1}.     

Optical elements for focusing of terahertz laser radiation in a given two-dimensional domain

Binary silicon-based diffractive optical element (DOE)—Gaussian-to-Square focuser (diameter of aperture is 30 mm) for the terahertz spectral range has been designed and characterized using terahertz radiation of the Novosibirsk Free Electron Laser (NovoFEL) at the wavelength of 141 μm. The preliminary experiments have demonstrated feasibility of application of binary silicon DOE for focusing of terahertz radiation into pre-given focal domain.     

Thermodynamics of Ba2Sm2/3UO6

The standard enthalpy of formation of crystalline Ba₂Sm_2/3UO₆ at 298.15 K, ?3040.0±7.5 kJ mol^?1, was determined by reaction calorimetry. The heat capacity of the compound in the range 80–300 K was measured by adiabatic vacuum calorimetry, and its thermodynamic functions were calculated. Its standard entropy of formation at 298.15 K is ?592.5±1.0 J mol^?1 K^?1, and the Gibbs energy of formation at 298.15 K, ?2863.5±8.0 kJ mol^?1. The standard thermodynamic functions of the reactions of the Ba₂Sm_2/3UO₆ synthesis were calculated and discussed.     

Thermodynamics of lutetium uranosilicate

The standard enthalpy of formation of crystalline Lu(HSiUO₆)₃ · 10H₂O at 298.15 K, ?10668.0±16.0 kJ mol^?1, and the standard enthalpy of its dehydration were determined by reaction calorimetry. The heat capacity of this compound in the range 80–300 K was measured by adiabatic vacuum calorimetry, and its thermodynamic functions were calculated. The standard entropy of formation at 298.15 K is ?3812.9±1.2 J mol^?1 K^?1, and the standard Gibbs energy of formation at 298.15 K, ?9531.0±16.5 kJ mol^?1. The standard thermodynamic functions of the reactions of the synthesis of lutetium uranosilicate were calculated and discussed.     

Synthesis and Physicochemical Study of Compounds in UO3-AkOk/(Ak = B, Si, Ge)-HO Systems

A synthetic analog of soddyite mineral, (UO₂)₂SiO₄·2H₂O, was prepared by hydrolyzing ammonium uranosilicate under hydrothermal conditions. The germanium-containing structural analog of soddyite, (UO₂)₂GeO₄·2H₂O, was synthesized by precipitation from solution. The compound UO₂(BO₂)₂ was prepared by reaction with molten boron oxide. The structures and properties of the compounds prepared were studied by X-ray diffraction analysis, IR spectroscopy, and thermography. The enthalpies of formation of the compounds were determined by adiabatic reaction calorimetry.     

Modification of the atomic structure and surface relief in recrystallized molybdenum foils tensile strained in ultrahigh vacuum

Changes in the atomic structure and surface morphology of a recrystallized molybdenum foil under the action of uniaxial tension in ultrahigh vacuum have been studied by low -energy electron diffraction (LEED) and atomic-force microscopy (AFM). It is established that uniaxial tension of the foil surface, which consists of separate blocks of dominating (100) face with 1 × 1 structure, leads to a local destruction of this face and the rotation of blocks. AFM topographs of various regions on the surface of fractured samples have been obtained. The variation of the LEED patterns agrees well with the evolution of the surface relief measured by AFM.     

Al–Cu–Li and Al–Mg–Li alloys: Phase composition,texture, and anisotropy of mechanical properties (Review)

The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al–Cu–Li and Al–Mg–Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S₁ (Al₂MgLi), T₁ (Al₂CuLi), and δ' (Al₃Li) phases. The fraction of the δ' phase in Al–Cu–Li alloys is shown to be significantly higher than in Al–Mg–Li alloys. Therefore, the role of the T₁ phase in the hardening of Al–Cu–Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al–Cu–Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al–Cu–Li and Al–Mg–Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.     

Thin-film cracking of acid tars

The method of thin-film thermal cracking of acid tar to manufacture liquid fuel and coke or liquid fuel and asphaltic binders has been developed. Differential thermal analysis of acid tar samples has been performed. A model of the thin-layer thermal cracking of acid tar and an algorithm for calculating the engineering parameters of the process have been proposed.