Optical spectroscopy of intermetallic compounds TbNi<Subscript>2</Subscript>Mn<Subscript> <Emphasis Type="Italic">x</Emphasis> </Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0, 0.5, 1)

The optical properties of intermetallic compounds TbNi₂Mn_x (x = 0, 0.5, 1) have been investigated using the ellipsometric method in the spectral range from 0.22 to 16 μm. The specific features of the modification of the dispersions of spectral characteristics with a variation in the manganese concentration have been determined. The behavior of the frequency dependences of the optical conductivity in the interband absorption region has been discussed in terms of the available data on the electronic structure of these compounds. The concentration dependences of a number of electronic parameters have been calculated.     

Analysis of nonlinearity of magnetization of YBa2Cu3O7 − x by the magnetic field modulation method

Temperature dependences of the magnetization harmonics of YBa₂Cu₃O_{7 ? x} monodomain samples are studied experimentally at temperatures of 77–120 K. It is found that nonlinearity of magnetization of YBa₂Cu₃O_{7 ? x} (higher harmonics generation) is observed up to temperatures T = 103–112 K, which are much higher than the superconducting transition temperature of this compound. At the same temperatures, the temperature dependence of resistivity begins to deviate from linearity. The observed singularity of the magnetization of YBa₂Cu₃O_{7 ? x} is associated with the emergence of a pseudogap state in this compound.     

Dispersion of zirconium dioxide by pulsed laser radiation

A technique for producing ZrO₂ dioxide nanoparticles under the action of pulsed laser radiation is developed. By the methods of transmission electron microscopy and X-ray phase analysis, it is shown that the high-temperature cubic phase of ZrO₂ is formed during laser ablation. The dependence of the size of ZrO₂ dispersed particles on the laser radiation intensity is determined. A thermodynamic one-dimensional model of laser ablation of zirconium dioxide is analyzed. The results of analytical computations of ablation of ZrO₂ particles are confirmed by experimental data.     

Local atomic environments and magnetic properties of copper binuclear azomethine complexes

Local atom environment in binuclear chelate Cu(II) complexes on the basis of azomethine ligands was investigated by extended X-ray absorption fine structure spectroscopy. The temperature magnetic measurements indicated ferro- or antiferromagnetic exchange in these complexes. A direct correlation between the character of the exchange magnetic interaction and the type of the ligand coordination in these complexes was established.     

Electronic structure and optical properties of the HoCoSi and ErNiSi compounds

The electronic structure and the optical properties of the HoCoSi and ErNiSi compounds are studied. Spin-polarized band calculations are performed in the local electron density approximation corrected for the strong electron–electron interactions in the 4f shell of a rare-earth ion (LSDA + U method [11]). The optical constants are measured by ellipsometry in a wide wavelength range, and the frequency dependences of a number of spectral parameters are determined. The calculated densities of states are used to interpret the structural features of the interband optical conductivities of the intermetallic compounds.     

Synthesis and structure of new composite hydrogels based on poly(N-vinyl caprolactam) with nanosized anatase

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Synthesis,structure, and properties of 2-[(4,6-di-tert-butyl-2,3-dihydroxyphenyl)thio]acetic acid amides

Russian Chemical Bulletin - New potential biologically active derivatives, in which the sterically hindered pyrocatechol moiety is linked through a 2-thioacetyl covalent bridge to a number of...     

Influence of “ytterbium nanofilm–silicon Si(111)” interfaces on the valence of ytterbium

The work function of ytterbium films of nanometer thickness (from 1 to 16 monolayers) has been measured. The films have been prepared by sputtering of ytterbium in an ultrahigh vacuum on n- and p-type Si(111)7 × 7 silicon substrates with an electrical resistivity from 1 to 20 Ω cm. It has been shown that, in the films with a thickness of less than 8 monolayers, the work function depends nonmonotonically on the amount of ytterbium deposited on the surface (Friedel oscillations), whereas in the films with a thickness of more than 8 monolayers, the work function takes on a constant value (3.3 eV) that exceeds the work function for macroscopic samples (2.6 eV). This difference is associated with the fact that, during the formation of an Yb–Si interface, the large difference in the work functions of ytterbium and silicon (4.63 eV) leads to the transfer of a significant fraction of electrons from the metal to the semiconductor. This transfer of electrons from the film to silicon is accompanied by the lowering of the Yb 5d level below the Fermi level. As a result, the valence of the metal and, accordingly, the work function increase.     

Methane Pyrolysis for Hydrogen Production: Specific Features of Using Molten Metals

Russian Journal of Applied Chemistry - Published data on noncatalytic pyrolysis of natural gas in molten metals are analyzed. The most illustrative results obtained in the past two decades are...     

Morphology of Composite Films Based on Poly(N-vinylcaprolactam) with Titanium Dioxide Nanoparticles

Crystallography Reports - PVCL25 and PVCL40 films have been synthesized by poly(N-vinylcaprolactam) (PVCL) aqueous solution flow coating and complete desiccation below...