Temperature dependence of the X-ray diffuse scattering intensity in V3Si in the temperature range from 8 to 300 K

Measurements of the diffuse X-ray scattering are performed from the (110) plane in V₃Si single crystal at different temperatures from 300 to 8 K. Contours of equal diffuse scattering intensity are drawn over the 440 node in the (001) and (111) sections. The temperature dependence and the anisotropy of the thermal diffuse scattering intensity distribution for this compound are analysed.     

Heterocycles containing a bridge nitrogen atom. 10. Unexpected closure of oxazole ring during the reaction of 2-chloro-1-phenacylpyridinium salt with potassium cyanate. Crystal structure of 2-(p-nitrophenyl)oxazolo-[3,2-a]pyridinium bromide and N-(p-nitrophenacyl)pyrid-2-one

Reaction of 2-chloro-N-(p-nitrophenacyl)pyridinium bromide with potassium cyanate in acetonitrile produces 2-(p-nitrophenyl)oxazolopyridinium bromide. Performing the same reaction in methanol N-(p-nitrophenacyl)pyrid-2-one was isolated. The structures of the obtained products were proved by X-ray structural data. For No. 9, see [1]. M. V. Lomonosov Moscow State University, Moscow 119899, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 542–549, April, 1999.     

Crystallochemical modeling, synthesis, and study of new tantalum and niobium phosphates with a framework structure

A crystallochemical approach is used to model the compositions of phosphates of pentavalent elements with the expected structure. New phosphates with a framework structure of the T ₂ ^I T ₃ ^2/III T ₁ ^2/V (PO₄)₃ type (T ^I = Na or K; T ^III = Al, Cr, or Fe; and T ^V = Nb or Ta) are synthesized and characterized by X-ray diffraction analysis (including high-temperature diffraction) and IR spectroscopy. It is established that, depending on the nature of the alkali cation (Na or K), these compounds are crystallized in two structural modifications: rhombohedral and cubic (sp. gr. R $\bar 3$ c and P2₁3, respectively). The unit-cell parameters and the thermal expansion coefficients of the phosphates under study are determined and the dependences of these characteristics on the nature of cations are established.     

Crystal Growth and Properties of the CuIn5S8 and AgIn5S8 Compounds

The optical and electrophysical properties as well as the structural characteristics and thermal expansion coefficients at different temperatures for the CuIn₅S₈ compound, grown by the vertical Bridgman-Stockbarger technique, and for the AgIn₅S₈ compound, prepared by the directed crystallization of the melt, were investigated.     

Preparation,structure and thermal properties of CuGa5Se8

The structural parameters, the axial thermal expansion coefficients and the characteristic Debye temperatures for the order vacancy compound CuGa₅Se₈ with the chalcopyrite‐related structure, prepared by the Bridgman technique, were determined at different temperatures between 90 and 650 K by the X‐ray diffraction method. The melting point of this compound was defined from the differential thermal analysis data. The anisotropy of thermal expansion in CuGa₅Se₈ is shown to exist with the coefficients along a ‐axis being larger than those along the c ‐axis throughout the temperature range studied.     

Diffuse X-ray scattering study of the temperature variation of elastic constants in indium arsenide

The elastic constants of indium arsenide have been determined in the temperature range from 80 to 750 K on n-type samples with a carrier concentration of about 8 · 10¹⁷ cm⁻³ by Wooster's method from the measurements of the thermal X-ray diffuse scattering intensities. An average decrease in the elastic constants with increasing temperature over the above mentioned temperature range is found to be about 8%.     

An ultra-low hydrolysis sol-gel route for titanosilicate xerogels and their characterization

In this work TiO₂-SiO₂ xerogels were prepared through an ultra low hydrolysis method using titanium and silicon alkoxide. The samples were heat treated to 500°C. The xerogels were characterized using TGA/DTA, FTIR, XRD and TEM. The samples showed the formation of Si–O–Ti bridges by its characteristic vibration within 925–960 cm⁻¹ range. Si–O–Si bond angles were calculated using the central force network model. The TiO₂ in all the samples crystallized on heat treatment to 500°C. The crystallite size calculated using the Scherer formula from the XRD was verified from the Transmission Electron Micrograph. Samples heat treated to 350°C remained amorphous and hence could be used as hosts for biomaterials and organic optical materials.     

Autowave Description of Plasticity of Materials with an Unstable Phase Structure at the Macroscale Level

Technical Physics - We consider the regularities of a plastic flow in materials with strain-induced phase transformation in titanium nickelide and trip steel as examples. The experimental analysis...     

Evidence of the Ferroelectric Polarization in Charge Transport through WTe2 Weyl Semimetal Surface

JETP Letters - We investigate electron transport along the surface of WTe2 three-dimensional single crystals, which are characterized by the coexistence of the conductivity and ferroelectricity of...     

Phytochemical Study of the Composition of the Unsaponifiable Fraction of Various Vegetable Oils by Gas Chromatography–Mass Spectrometry

Journal of Analytical Chemistry - We developed a method for quantitatively analyzing some components of the unsaponifiable fraction of edible oils and validated its characteristics. The component...