Yu. A. Osip'yan

Hydrogen absorption and desorption kinetics in fullerite C60 single crystals. Low-temperature micromechanical and structural characteristics of the interstitial solid solution C60(H2)x

The microhardness HV and lattice parameter a of C60 single crystals are measured at room temperature as functions of the hydrogen saturation time t for several values of the saturation temperature (250, 300, and 350°C) at a fixed hydrogen pressure p=30atm. According to the measurements of HV and a, the kinetics of hydrogen absorption is described by a simple exponential law with a single, temperature-dependent characteristic time. In highly saturated samples the microhardness is 4 times greater than for the initial C60 crystal, while the lattice parameter is 0.2% larger. The temperature dependence of the microhardness HV and lattice parameter a of C60(H2)x crystals is investigated in the temperature interval 77–300K. The introduction of hydrogen lowers the temperature of the fcc–sc phase transition, and the transition becomes strongly broadened in temperature. The dependence of the microhardness of the saturated sample on the hold time in air at room temperature is described by the sum of two exponentials...

Influence of Magnetic Field on Critical Stress and Mobility of Dislocations in Silicon

We have found the effect of strong influence of magnetic field tre atm nt on the starting stresses of individual dislocations in Czochralski-gr own silicon (CZ-Si). It is shown that the exposure of CZ-Si samples with dislocations at room temperatur to magnetic field reduces essentially the starting stresses for dislocation motion. T he effect is absent in FZ-Si samples. We suppose that magnetic field causes the singlet-triplet transiti o in thermally exited states of oxygen complexes in a dislocation core that changes the state of oxy gen already situated on dislocations in such a way that the mean binding energy of oxygen w ith a dislocation is diminished.

Endor of a dislocation center in a deformed silicon

Abstract We present the first ENDOR measurements on dislocations in silicon, which measurements directly show the extended nature of the electron wave function on the dislocation.

Micromechanical properties of C70 single crystals in the temperature range 77–350 K

Hexagonal single crystals of C70 down to 1–2 mm in size were grown, which allowed the investigation of their low-temperature mechanical properties for the first time. Morphology, microplasticity anisotropy, and the temperature dependence of Vickers microhardness HV (T) of the C70 crystals involving all known phase transitions were studied with the aid of optical microscopy and microindentation in the temperature range 77–350 K. The association of the features of HV (T) dependence with orientation phase transformations was analyzed. It is suggested that microplasticity anisotropy of the C70 crystals correlates with the active slip systems.

Influence of Magnetic Field on the Unlocking Stress for Dislocation Motion in Cz-Si Depending on Pre-Annealing Time

We investigated the effect of magnetic field on the unlocking stress for dislocations in Cz-Si, measured at 600oC, depending on the thermal prehistory of samples. The effect increases with increasing of the duration of sample annealing at 600oC before the magnetic field treatment. The experimental data are consistent with the assumption that the magnetic field stimulate some changes in configuration of oxygen accumulated at dislocations before the magnetic field treatment, but not the state of oxygen in a bulk.

Development of shaping technologies for crystals grown from melts

The development of technologies for growing crystals with a given shape and designing the growth equipment for the Czochralski and conventional and modified Stepanov methods have been considered. The reviewed experimental data lead to the conclusion that it is possible to provide three-dimensional control of the crystal geometry with the aid of a die in the growth process.

Deformation and structure of YBCO ceramics and single crystals in the temperature range 300–1200 K

Abstract The data deformation and structure of YBCO ceramics and single crystals have been reported. It has been concluded that deformation of ceramic specimens is governed by processes of grain-boundary break-down. In syngle crystal specimens and ceramic crystallites the deformation is followed by dislocation processes, alterration in the twin structure, and microcracking.

INVESTIGATION OF ONE-DIMENSIONAL DEFECTS IN SI USING THE EDSR

The electron-dipole spin resonance (EDSR) is shown to be a powerful tool for investigation of electronic properties of extended defects in semiconductors. Using EDSR for plastically deformed Si, the existence of one dimensional dislocation energy band is found and the temperature dependence of electron mobility in this band is measured.