The influence of pressure on the luminescence of zinc sulphide single crystals

Experiments were made which show that luminescence originated under the application of pressure on the single crystals of zinc sulphide. The calculated formula gives the same dependence of luminescence on the change of pressure dP/dt as in [1], [2].     

The influence of light intensity on surface recombination in GaS single crystals

Gallium sulphide (GaS) is a layer structure semiconductor with relatively wide energy gap (E_g (295 K) = 2.5 eV and E_g (80 K) = 2.62 eV). It has potential applications in some areas of optoelectronics. This paper presents the investigations of the influence of light intensity on surface recombination velocity of charge carriers in GaS single crystals. To attain this purpose spectral dependences (between 420 and 550 nm) of absorption coefficients, reflectivity coefficients and photoconductivity were measured in vacuum. The investigations were performed for various light intensities in several temperatures from 80 to 333 K. The least square method was applied to fit the theoretical dependences of photoconductivity on wavelength and intensity of illumination at these temperatures. From the fittings the temperature and light intensity dependences of surface recombination velocity and bulk lifetime of charge carriers were obtained.     

The influence of rest on the micromechanical properties of preliminarily deformed MgO single crystals

The influence of a prolonged rest at room temperature on the activity of acoustic emission upon microindentation of preliminarily deformed MgO single crystals is investigated. It is found that the number of acoustic emission signals after the specimens have rested increases at low loads P (～50 g) applied to an indenter and decreases at high loads P (～200 g). The change observed in the activity of acoustic emission depends on the degree of preliminary deformation. It is assumed that the observed effects are associated with the difference between the sources of acoustic pulses: the main contribution to the activity of acoustic emission comes from the breakaway of dislocation pileups at low loads P and from the formation of microcracks and macrocracks at high loads.     

The influence of impurities on the electric and thermoelectric properties of CdSb single crystals

The influence of impurities on the electric and thermoelectric properties of CdSb single crystals prepared by the modified Czochralski method and the method of zone melting was studied. It was found which impurities are electrically active and which give rise to electron and hole conductivity and a schematic model of their substitutions in the CdSb lattice was proposed. The temperature dependence of the mobility was found for both electrons and holes and the density effective masses were determined.Reported by L. toura at the Conference on Thermoelectricity, 10–12. 7. 1961, Durham, England [26].     

The influence of the stoichiometry on the Eu nuclear spin-spin relaxation in EuO single crystals

The ¹⁵³Eu spin-spin relaxation for two spherical EuO single crystals of different composition has been measured for two saturating field values of 2 and 6 T. The relaxation can be described by two time constants, a short one increasing with the magnetic field, arising from the Suhl-Nakamura coupling and a long one, due to the dipolar coupling, which is field independent. It is shown that the number of nuclei which are relaxed due to the dipolar coupling increases at increasing magnetic fields, in agreement with the Suhl-Nakamura theory. For the sample which is nearly stoichiometric the relative number of nuclei which is relaxed due to the SN coupling is much larger than for the sample which contains an excess of Eu atoms.     

The influence of defects in compound single crystals on the critical angle of planar channeling

The theoretical treatment of the relation between the critical angle of planar channeling and the characteristics of crystal lattice defects is carried out. The predictions are made about some typical forms of the critical angle dependence on the mean-square static displacement produced by defects, and then these predictions are detailed for the cases of homogeneous disordering, spherical clusters of point defects and dislocation loops. Analytical results are supported by the exact computer calculations for the defects in the intermetallic A-15 compounds.     

The influence of oxygen partial pressure on recovery creep in magnetite single crystals

Creep tests of magnetite single crystals have been performed in compression at high temperatures (between 1000 and 1340°C). The main goal was two-fold: First of all, the determination of the dependence of steady state creep rate as a function of the oxygen partial pressure in the external atmosphere. Secondly, the comparison of this dependence with that of oxygen self-diffusion coefficient with the partial oxygen pressure. This second one had been reported in literature previously. Both are quantitatively very similar. This fact has allowed us to discuss some aspects of the minority point defects in the oxygen sub-lattice of this oxide.     

The diffusion of silver ions in AgBr/Agi sheet crystals

Abstract

The results of the tracer diffusion of Ag⁺ by chemical microsectioning technique in AgBr/I sheet crystals up to the solubility limit in the temperature range 110–240°C are presented. The monotonic increase in the diffusivity and decrease of the activation enthalpy for diffusion with the increase of the iodide component in AgBr result from the decrease of the formation energy for Frenkel defects with the increase of elastic strain introduced by the oversized iodide ions.     

Optical absorption in MnIn2S4 single crystals

Optical absorption in MnIn₂S₄ single crystals has been studied. Direct and indirect optical transitions are found to occur at photon energies of 1.90?C2.16 eV in the temperature range of 80?C342 K. The temperature dependence of the band gap is determined; its temperature coefficients E _gd and E _gi are found to be ?4.84 × 10^?4 and ?6.33 × 10^?4 eV/K, respectively. The electron-phonon interaction is the main mechanism of the temperature shift of the intrinsic-absorption edge. MnIn₂S₄ single crystals exhibit anisotropy in polarized light at the absorption edge in the temperature range of 90?C190 K; the nature of this anisotropy is explained.     

The influence of CO on hydrogen sorption by Pd(111) single crystals

A novel method of calibration based on the solubility data of hydrogen in palladium is applied to both the analysis of thermal desorption spectra of hydrogen from Pd(111) and to studies on the influence of adsorbed carbon monoxide on the behaviour of adsorbed and absorbed hydrogen, at room temperature. For clean Pd(111) (θ_CO < 0.04 ML) the comparison of experimental and theoretical spectra shows that part of the hydrogen originally adsorbed on the surface dissolves. This hydrogen appears at higher temperatures as a diffusion tail. A strong influence of coadsorbed CO on the maximum hydrogen coverage was observed in the low-coverage region where usually the existence of isolated CO molecules on the surface can be expected. For hydrogen sorption comparison of experimental data with those calculated on the basis of the solution of Fick's second law for a plane sheet indicates that this process is solely diffusion controlled. On the other hand, a strong barrier for desorption of dissolved hydrogen is observed at θ_CO = 0.33 ML. It is concluded that the influence of CO on the behaviour of dissolved hydrogen may be consistently explained if there is a CO-induced change in the polarization state of adsorbed hydrogen atoms.     

Effect of neutron irradiation on the IR absorption spectra of cupric oxide single crystals

A strong increase of the absorption coefficient with photon energy increasing from 0.1 to 1.0 eV is observed in the spectra of CuO single crystals irradiated with neutrons to a fluence of 5×10¹⁸ cm⁻². The difference of the absorption coefficients before and after irradiation depends on the wavelength as λ⁻². The effect of neutron irradiation on CuO is qualitatively similar to that of neutrons on other semiconductors (for example, GaAs) and differs from that obtained by irradiating CuO with charged particles. Zh. Tekh. Fiz. 69, 98–99 (December 1999)