Antisite defects and valence state of vanadium in Na<Subscript>3</Subscript>V<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

Electron paramagnetic resonance (EPR) studies have been performed with the aim of determining the valence state and local crystal structure of the nearest environment of vanadium ions in the initial, charged, and discharged samples of the cathode material Na_xV₂(PO₄)₃ (1 ≤ x ≤ 3). It has been found that the charged sample (x = 1) is characterized by an intense signal corresponding to V⁴⁺ ions located in a highly distorted octahedral crystal field. An EPR signal with the g-factor close to the g-factor of the V⁴⁺ ion has also been observed in the initial sample (x = 3), where the intensity of the resonance signal is one order of magnitude lower than that in the charged sample. It has been revealed that the resonance signal under consideration is associated with the formation of antisite defects when a part of vanadium ions are located in sites of sodium ions. It has also been found that the intensity of this signal increases after a complete charge–discharge cycle (x = 3).     

A new approach to solving homogeneous Riemann boundary-value problem on a ray with infinite index

We consider a Riemann boundary-value problem with infinite Gakhov’s index. The boundary data are defined on positive ray of the real axis. We solve the problem by means of removal of singularity of boundary data at the infinity. This approach is analogous to Gakhov’s method of elimination of singularities in the problemswith finite indices, but we use another eliminating factors.     

Experimental study of ultrasmall-angle scattering of electron bremsstrahlung gamma-quanta (<Emphasis Type="Italic">E</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis></Subscript> = 11.8 MeV)

The study of the angular distribution of electron bremsstrahlung γ-quanta scattered from the reflector surface through an angle of 166 μrad reveals the emergence of total internal reflection of γ quanta with an energy E _γ ≤ 300 keV.     

Photoelectrochemical Behavior of Heterosystem AIIBVI/TiO2–RuO2 in Electrolysis of Aqueous Electrolytes

Anodic polarization curves for the CdSe/TiO₂–RuO₂ heterosystem and its components in 0.5 M Na₂SO₄ with and without illumination are compared. It is shown that the outer film consisting of titanium and ruthenium mixed oxide protects A^IIB^VI semiconductors from corrosion and promotes the electrocatalytical activity of the heterosystem in the photosplitting of water.     

On the role played by bending vibrations in heat transfer in layered crystals

The temperature dependences of the thermal conductivity of layered crystals (LCs) of graphite, boron nitride, gallium sulfide, etc., are analyzed. It is shown that the bending branch of vibrations typical of LCs determines the behavior of the thermal conductivity only in the region of its increase. The decrease in thermal conductivity upon heating cannot be explained by taking into account the bending vibrations only, and phonon-phonon interaction processes become effective only in the case of excitation of other branches in the acoustic spectrum.     

High temperature catalytic synthesis of higher hydrocarbons from methane

It has been revealed that methane conversion to higher hydrocarbons over MgO catalyst involves the direct participation of heterogeneous catalyst at contact times of up to 3s and is a homogeneous reaction at 10s.

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MgO. , 3 . , 10 . .

     

Intercalation of Toluidines into α-Zirconium Hydrogenphosphate

Intercalates of o-, m-, and p-toluidine into α-Zr(HPO₄)₂ · H₂O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom.