Specific features of magnetic properties of three-component magnetic superlattices based on Fe/Co/Mo

Synthesis of three-component magnetic superlattices based on the Fe/Co/Mo system by cathode sputtering in an electron-oscillating discharge and their complex investigations have been performed for the first time. The fields have been investigated by X-ray diffraction, vibrational magnetometry, and Mössbauer spectroscopy with the use of completely computerized systems. Oscillations of the main magnetic parameters with a change in the Mo thickness and giant spontaneous magnetization have been found. The properties of three-component superlattices are compared with those of the analogous system based on Fe/Mo.     

Protected optical line coding based on multiple-valued logics

Multiple-valued logic functions given by the Allen-Givone algebra are proposed for use in optical nonquantum communication channels as tools for generating a set of secret keys of very high dimension.     

Synthesis and crystal structure of the new complex oxide Ca<Subscript>7</Subscript>Mn<Subscript>2.14</Subscript> Ga<Subscript>5.86</Subscript>O<Subscript>17.93</Subscript>

The complex oxide Ca₇Mn_2.14Ga_5.86O_17.93 was synthesized by the solid-state reaction in a sealed evacuated quartz tube at 1000 °C. Its crystal structure was determined by electron diffraction and X-ray powder diffraction. The structure can be represented as a tetrahedral framework, viz., the polyanion [(Mn_0.285Ga_0.715)₁₅O_29.86]^19- stabilized by the incorporated cation [Ca₁₄GaO₆]₁₉₊. The polycation consists of the GaO₆ octahedra surrounded by the Ca atoms, which are arranged to form a cube capped at all places. The tetrahedral framework is partially disordered due to the presence of tetrahedra with two possible orientations in the positions (0, 0, 0) and (x, x, x) with x ≈ 0.15 and 0.17. The relationship between the Ca₇Mn_2.14Ga_5.86O_17.93 structures and related ordered phases with the symmetry F23, as well as the influence of the oxygen content on the ordering in the tetrahedral framework, are discussed.     

X-ray powder diffraction study of polytetrafluoroethylene

Samples of polytetrafluoroethylene were studied by X-ray diffraction. A quantitative X-ray powder diffraction analysis of three components of the polymer was performed for the first time. All samples of polytetrafluoroethylene were found to be three-phase and consist of one crystalline and two amorphous phases. One of the amorphous phases is composed of low-molecular-weight products. The structure of the latter phase was established for the first time by X-ray diffraction methods and computer simulation.     

Mass spectrometry of π-complexes of transition metals 38—keto-enol tautomerization of molecular ions of acetyl- and propionyl-ferrocenes in the gas phase

Fragmentation of the acetyl- and propionyl-ferrocenes under electron impact together with the rupture of C? CO bonds, characteristic of ketones, also includes elimination of water and migration of the OH group to the central metal atom, which is due to keto-enol tautomerization of the acyl group in molecular or fragment ions.     

Inducing superconductivity and structural transformations by fluorination of reduced YBCO

Bulk superconductivity with T_c up to 94 K has been induced by fluorination of non-superconducting YBa₂Cu₃O_6.11 using XeF₂ as a fluorination agent. Strong changes on X-ray patterns were found after fluorination of reduced YBCO. High resolution electron microscopy of superconducting samples showed the presence of a new phase with c ≈ 13 Å which exists as noticeable areas included within a matrix of the 123 structure or which occurs as isolated defects with a limited extension. All fluorinated compounds exhibited a strong disorder along the c-direction resulting in a ‘loss’ of c-parameter on X-ray patterns. The present results demonstrate that fluorine indeed enters the YBCO structure with a significant structural rearrangement for the high level of fluorination. The structure of the fully fluorinated YBa₂Cu₃O₆F₂ phase, possibly responsible for superconductivity, has been deduced from high resolution electron microscopy.     

Electrodeposited paint-and-varnish nickel–polymer coatings

Specific features of preparation of paint-and-varnish nickel–polymer coatings by joint cathodic electrodeposition of an amine-containing oligomeric electrolyte and nickel were studied. The coatings obtained exhibit layer-by-layer heterogeneity, with the lowest layer constituted by an intermetallic compound of nickel with iron. The coatings are characterized by higher degree of cross-linking compared to the polymer coatings without nickel. A paint-and-varnish formulation based on a nickel–polymer film-forming agent was developed for electrodeposition of corrosion- and wear-resistant coatings.     

Effect of the degree of extension on the phase composition and tendency toward mesomorphism of UHMWPE in gel-spun oriented fibers

Structural transformations of UHMWPE-based fibers prepared by orientational drawing have been studied by the combination of SAXS and WAXS methods, photo- and diffractometry, and isometric DSC measurements in a wide temperature range. A sequence of phase transformations and other structural changes has been followed and identified during the orientational deformation of the fibers in a wide range of draw ratios from 1 to 85 within the temperature interval from room temperature to the melting temperature of the polymer.