A. V. Bazhenov

Properties of a composite material based on multi-walled carbon nanotubes and an ionic liquid

A solid-phase composite material based on multi-walled carbon nanotubes and an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) has been synthesized. It has been found using infrared spectroscopy that vibrational modes of the ionic liquid are shifted by 4–12 cm−1 toward lower energies with respect to those observed in the initial fluid due to the interaction of ionic liquid molecules with the nanotubes. Electron microscopy has revealed that, in the composite, the ionic liquid is present on the surface of nanotubes and partially inside them. It has been shown that the degree of extraction of lanthanides from aqueous solutions with the use of the synthesized composite increases with increasing content of the ionic liquid in it.

Synthesis of a periodic SiC/C nanostructure

Highly porous periodic structures consisting of a three-dimensional replica of pores in the initial opal lattice have been synthesized by high-temperature thermochemical treatment of opal matrices filled with carbon compounds, followed by dissolution of silicon dioxide. It has been shown that the main phases of the composite are carbon and silicon carbide. Based on the X-ray diffraction, Raman, and IR spectroscopy data, it has been assumed that the composite contains fragments of hexagonal diamond. The photoluminescence and optical reflection spectra of the composites have been measured.

Three-dimensional periodic lattice of ZrO2 nanocrystals in transparent silica matrix

The conditions for synthesizing an opal-zirconia-carbon nanocomposite in the form of monolithic (without pores) transparent silica with an ordered distribution of nanocrystals throughout the sample have been determined. Zirconia nanocrystals form a three-dimensional periodic lattice of nanoclusters with sizes ranging from several nanometers to several tens of nanometers. This nanocomposite exhibits properties typical of photonic crystals. The samples have been studied using electron microscopy, X-ray diffraction, photoluminescence, and Raman scattering. The structural state and spatial arrangement of zirconia nanocrystals and carbon clusters in the nanocomposite have been elucidated. Optical transmission and optical reflection photoluminescence spectra of the nanocomposites have been measured.

Influence of nanoparticles of cesium sulfate and deformation on structure, vibration spectra, and luminescence of polystyrene

Significant changes in infrared absorption spectra of polystyrene upon the addition of cesium sulfate nanoparticles to it are observed, which is due to two variants of attachment of organic molecules to nanoparticles (through hydrogen and pi bonds). The relation between the bonds changes significantly during deformation of polystyrene/cesium sulfate composite owing to differences in the mechanical strength thereof. In its turn, the differences in atomic and electronic bond structures result in a significant differentiation of their influence on light emission processes, making it possible to control the scintillation characteristics of polystyrene/nanoparticle composites via regulating their composition and morphology.

Structural ordering upon annealing of europium molybdate subjected to pressure treatment

It has been found that treatment of europium molybdate single crystals under high uniform pressure leads to radical changes of the IR reflectance spectra of the samples. Instead of a series of narrow lines, which are characteristic of the spectrum of the initial crystal, the spectrum of the sample subjected to pressure treatment exhibits broad bands. As follows from the results of X-ray diffraction measurements, this transformation of the IR spectra is associated with the fact that, after pressure treatment, the sample represents an amorphous matrix with inclusions of nanocrystals of the high-pressure phase. In the IR spectra, the high-pressure phase manifests itself in the form of a new line at approximately 600 cm−1. After annealing of the sample with an increase of the temperature from 100 to 400°C, the high-pressure phase disappears. A further increase of the annealing temperature to 550°C leads to the recovery of the crystal structure of the initial β′ phase of europium molybdate and to the appearance of lines corresponding to the α phase.

Oriented ZnO Nanorods and Their IR Reflection Spectra

Oriented ZnO nanorods have been grown on sapphire and silicon substrates by pulsed laser deposition. It is established that IR spectroscopy gives information about the crystal structure of nanorods, their conductivity, and degree of orientation, depending on the growth conditions. A size effect is found: softening of optical ZnO phonons with a decrease in the nanorod diameter.

Optical phonon spectra of lutetium fluoride, oxyfluoride, and lutetium oxide nanoparticles

Nano-and microcrystalline LuF3 phases have been synthesized with particle sizes of 30 nm and 30 μm, respectively. Analysis of the IR reflection spectra measured at T = 300 K showed that the nanophase differs from the microcrystalline phase by reduced optical phonon frequencies. It is established that annealing of the LuF3 nanophase in air leads to the formation of nanoparticles of the LuO1 − xF1 + 2x and Lu2O3 compositions. The IR reflection spectra of the nanophases indicate that these nanoparticles consist of an oxyfluoride core surrounded with a Lu2O3 shell; the latter is in the strained state.

Structure and Properties of SiO x Films Prepared by Chemical Etching of Amorphous Alloy Ribbons

The structure and the physical properties of amorphous SiOx films prepared by chemical etching of an iron-based amorphous ribbon alloy have been studied. The neutron diffraction and also the atomicforce and electron microscopy show that the prepared visually transparent films have amorphous structure, exhibit dielectric properties, and their morphology is similar to that of opals. The samples have been studied by differential scanning calorimetry, Raman and IR spectroscopy before and after their heat treatment. It is found that annealing of the films in air at a temperature of 1273 K leads to a change in their chemical compositions: an amorphous SiO2 compound with inclusions of SiO2 nanocrystals (crystobalite) forms.

Interaction of hydrofullerite C60H42 with air

The transmission and Raman spectra of C60H42 samples synthesized at a high hydrogen pressure and stored under different conditions have been measured. It has been found that, upon interaction of the compound with air, a part of C60-H chemical bonds are replaced by C60-O-H bonds. It has been experimentally shown that the observed changes in the vibrational and electronic properties of C60H42 are caused by the interaction of the compound with atmospheric oxygen and water vapor. The rate of oxidation of the studied samples is significantly less than the value previously published for the oxidation of the C60H36 compound synthesized by the reduction of fullerene C60 dissolved in different solvents with the use of Zn/HCl. This is explained by the fact that particles of the product of the hydrogenation at a high hydrogen pressure are polycrystals with relatively large sizes, unlike the fullerene hydrides synthesized by the reduction of C60 with Zn/HCl.

Fullerit C60 single crystals grown on earth and in space

Fullerit C60 single crystals were grown by sublimation on Earth and under microgravity during the FOTON-M3 mission using the same growth parameters and the same multizoned electrovacuum POLIZON-M furnace. IR spectroscopy and X-ray measurements revealed the considerably better crystal structure of the crystals grown under microgravity.