Magnetoresonant hardening of silicon single crystals

JETP Letters - A microwave magnetic field crossed with a static field was found to exert a resonance effect on the dislocation mobility in single crystals of p-type silicon. The frequency of...     

Ordering of oxygen in halogen treated 1-2-3 systems as studied by NQR

We have investigated the low-temperature behavior of Cu NQR for iodinated RBa₂Cu₃O _x (R = Y, Gd) compounds. The different influence of Gd spins on the Cu(1) and Cu(2) sites was used to separate the contributions of both sites in the spectra. The distinct NQR lines associated with the different oxygen-coordinated Cu(1) sites have been observed. The NQR spectra of the Cu(1) sites show that the iodine treatment gives rise to the modifications of the oxygen sublattice. From the analysis of the NQR spectra of the Cu(1) sites follows an increase of the average length of the Cu(1)-O chains at treatment.     

Pecularity of lithium electrodiffusion into fulleride single crystals

Diffusion of lithium cations in C₆₀ single crystals driven by an electric field has been studied. It was found that the stoichiometry of C₆₀ single crystals can be changed with respect to lithium by injection of Li⁺ ions through the heterojunction Li₇SiPO₈|C₆₀ and electrons through the heterojunction C₆₀| Graphite. The double charge injection changes the stoichiometry of lithium in a C₆₀ single crystal and increases both the lithium ionic and electronic conductivity. The electronic conductivity in Li_xC₆₀ crystals is non-metallic in nature. The temperature dependence of the electronic conductivity lithium doped C₆₀ single crystals was investigated. It was found that electrons occupied the lowest singlet exited states (LUMO) and that this leads to the appearance of an intensive EPR signal. The temperature dependence of the concentration of paramagnetic centers was investigated. Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.     

On the mechanical properties of C60 fullerite crystals

First experimental data on the plasticity, strength and microhardness of C₆₀ fullerite crystals are reported. It is concluded that the mechanical properties of the crystals studied are isotropic, and the values of their breaking point are low. The obtained results are compared with those for other materials (graphite, indium etc.).     

The electron-dislocation interaction and electronic effects at low-temperature deformation

The effect of the electronic state of crystals on the processes of their plastic flow is considered. Presented are the results of the observation and study of the effects of the electrondislocation interaction at a low-temperature deformation of metals.     

Dislocation microwave electrical conductivity of semiconductors and electron-dislocation spectrum

The experimental data are presented on the microwave electrical conductivity of dislocated silicon and germanium as well as on the effect of light on the dislocation ESR signal. Based on the results obtained the new scheme of dislocation electron energy spectrum is suggested.     

Thermally stable hydrogen compounds obtained under high pressure on the basis of carbon nanotubes and nanofibers

Compounds containing 6.3–6.5 wt % H and thermally stable in vacuum up to 500°C were obtained by annealing graphite nanofibers and single-walled carbon nanotubes in hydrogen atmosphere under a pressure of 9 GPa at temperatures up to 45°C. A change in the X-ray diffraction patterns indicates that the crystal lattice of graphite nanofibers swells upon hydrogenation and that the structure is recovered after the removal of hydrogen. It was established by IR spectroscopy that hydrogenation enhances light transmission by nanomaterials in the energy range studied (400–5000 cm^?1) and results in the appearance of absorption bands at 2860–2920 cm^?1 that are characteristic of the C–H stretching vibrations. The removal of about 40% of hydrogen absorbed under pressure fully suppresses the C–H vibrational peaks. The experimental results are evidence of two hydrogen states in the materials at room temperature; a noticeable portion of hydrogen forms C–H bonds, but the most of the hydrogen is situated between the graphene layers or inside the nanotubes.