http://dspace.nbuv.gov.ua:80/handle/123456789/132723 2026-04-12T23:14:51Z http://dspace.nbuv.gov.ua:80/handle/123456789/136628 Week fragmentation of round plates Brodskii, R.Ye.; Tur, A.V.; Yanovsky, V.V. The simple model of binary week fragmentation of round plates is considered. It is shown, that distribution function of fragments by masses is depended on choice of fissures arise mechanism. The exact distribution function of fragments by masses is obtained with isotropic and anisotropic fissure spreading in plates and its asymptotic behaviour in small and large masses regions is studied. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135381 Formation mechanisms and geometry of the crack assemble formed under uniaxial cyclic compression of NaCl single crystals Boyko, Yu.I.; Volosyuk, M.A.; Kononenko, V.G. Using light-scattering method, the cracks formation was experimentally studied in NaCI single crystals under uniaxial cyclic compression (10⁷ N/m²) during ~10 c at room temperature and following annealing at T = 500°C for ~10 min. The observed cracks were sorted (conventionally, in comparison with wavelength of the light used) into small ones showing the pattern of isotropic scattering, and big ones showing the scattering pattern with sharp maxima. It was established, that both small and big cracks were positioned in {100} planes and formed by Cottrell mechanism. In late stages of deformation, a little quantity of cracks was observed in {110} planes. Among possible mechanisms of the cracks formation, Stroll mechanism is considered as the most probable in our case of small deformations and stress. As the cracks are accumulated, the formation of ordered compact groups of cracks is found which are analogous to ordered groups of solid foreign-phase precipitations under decomposition of supersaturated solid solutions. The volume fraction of small cracks is by two orders of value higher than the volume fraction of big ones. The volume fractions of both kinds of cracks increase with the cycle number, but the big crack volume fraction increases much faster. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135380 Electronic structure peculiarities of disordered Mn and Co diphosphates Karbivskyy, V.L.; Smolyak, S.S.; Zagorodniy, Yu.A.; Kasiyanenko, V.H. Electronic structure peculiarities of disordered diphosphate —Mn₂₋ₓCoₓP₂O₇*5H₂O, with x = 0, 0.6, 1.0, 1.9, 2.0, were studied by XPS and X-ray emission spectroscopy. Substitution in the different degree of cobalt by manganese leads to a charge redistribu¬tion in the metal sublattice and results in increase of the chemical bond ionicity between oxygen anions and the metal cations. Such charge redistribution is responsible for forma¬tion of the states laying in the upper part of the valence band. 2012-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/135379 Evolution of normal electrical resistance in oxygen underdoped Ho₁Ba₂Cu₃O₇₋δ single crystals in the process of application-removal of high hydrostatic pressure Vovk, R.V.; Khadzhai, G.Ya.; Nazyrov, Z.F. The influence of high hydrostatic pressure on electrical resistance in afr-plane of oxygen underdoped Ho₁Ba₂Cu₃O₇₋δ has been studied. It was found that high-pressure-in-duced redistribution of labile oxygen leaded to increasing phase separation, which was accompanied by a process of structural relaxation and uphill diffusion in the bulk of the pilot sample. It has been suggested that the generation of low-temperature (oxygen-depleted) phase can occur at twin boundaries. The temperature dependence of the resistivity above Tc can be accurately approximated by the model s-d-electron scattering by phonons. Application of high pressure leads to a decrease of the resistance, which at high temperatures is much larger than at low temperatures. This may be due to the weakening the electron-phonon interaction with increasing pressure. 2012-01-01T00:00:00Z