http://dspace.nbuv.gov.ua:80/handle/123456789/132726 2026-04-13T04:03:07Z http://dspace.nbuv.gov.ua:80/handle/123456789/135329 Mechanisms of microvoid formation within KCl single crystals in the pulse energy release area of laser focused radiation Boyko, Yu.I.; Volosyuk, M.A.; Kononenko, V.G. Mechanism of micropore formation in the area of pulse energy release of the laser focused radiation in KCI single crystals was studied experimentally at low (77 K) and room (300 K) temperatures. The pulse duration was varied from 510⁻⁸ s to 10⁻³ s and pulse energy — from 1 to 20 J. The observed pore sizes were (0.75 ÷ 120)*10⁻⁶ m. The dislocation structure around the pores and photo-elastic stress pattern were studied. For the experimental results obtained the following values were estimated: the initial pressure in the relaxation area (2*10⁹N/m²), the heated-up "nucleus" temperature (1100 K), and the laser pulse absorbed energy corresponding to a given pore size. As it is seen from the experiments, the dislocation mechanism contribution into the substance transport for pore sizes less than 10⁻⁵ m is 2 ÷ 4 %, while the rest of substance is taken away by crowdion (interstitial atom) mechanism. The diffusion contribution into the mass transport is found to be negligible. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135328 Strain induced effects in p-type silicon whiskers at low temperatures Druzhinin, A.A.; Maryamova, I.I.; Kutrakov, O.P.; Liakh-Kaguy, N.S.; Palewski, T. Complex studies of strain induced effects in boron doped p-type silicon whiskers with [111] crystallographic direction in the wide temperature range 4.2 - 300 K at magnetic fields up to 14 T and under high-energy electron irradiation were carried out. The peculiarities of piezomagnetoresistance of Si whiskers heavily boron doped and with boron concentration in the vicinity of metal-insulator transition were determined. The influence of electron irradiation with energy 10 MeV and fluence Φ = 5*10¹⁷ el/cm ² on the gauge factor of boron doped Si whiskers at low temperatures have been also studied. High-sensitive piezoresistive sensor to measure pressure of liquid helium on the basis of silicon whiskers with a giant gauge factor was developed. Heavily doped Si whiskers with classic piezoresistance have been successfully used in mechanical sensors operating in the wide temperature range 4.2 - 300 K. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135327 HgCrCdSe as an element of new heterostructure HgCrCdSe/HgMnTe Bekirov, B.; Ivanchenko, I.; Popenko, N.; Tkach, V. By using the EPR method we show that the introduction of the fourth component as the cadmium (Cd) into the solid solution CrₓHg₁₋ₓSe allows for increasing the transition temperature of magnetic ordering in this compound. The resistance, magnetoresistance, and current-voltage characteristics of new heterojunctions HgCdCrSe/HgMnTe are measured as a function of temperature and external magnetic field. The appearance of nonlinear plot on the reverse branch of experimental current-voltage characteristic at a temperature below the temperature of magnetic ordering can be explained by the appearance of spin-polarized current. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135326 Radiation induced defects in M₁₋ₓPrₓF₂₊ₓ (M²⁺ = Ca, Sr, Ba, x = 0.35) solid solutions Boiaryntseva, I.A.; Shiran, N.V.; Gektin, A.V. Radiation-induced processes in M₁₋ₓPrₓF₂₊ₓ (M²⁺ = Ca, Sr, Ba, x = 0.35) solid solutions have been studied. It is shown that the radiation coloration of M₀.₆₅Pr₀.₃₅F₂₃₅ crystals is due to the trapping of charge carriers at anion sublattice defects. The efficiency of color centers formation in the investigated solid solutions grows in the row Ca —> Sr —> Ba. It may be caused by the increase of the pre-irradiation defects as a result of the different cluster types formation in M₀.₆₅Pr₀.₃₅F₂₃₅ mixed systems. 2012-01-01T00:00:00Z