Time filter

Source Type

Rassolov S.,Aa Galkin Donetsk Institute For Physics And Engineering Of Nas Of Ukraine | Rassolov S.,Luhansk National Taras Shevchenko University | Tkatch V.,Aa Galkin Donetsk Institute For Physics And Engineering Of Nas Of Ukraine | Maslov V.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | And 5 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2010

The nanocrystallization behaviour of Al86Ni6Co2Gd3Y2Tb 1 amorphous alloy has been studied by X-ray diffraction methods involving small angle scattering, resistance measurements and differential scanning calorimetry. It has been established that the transformation in amorphous alloy investigated occurs mainly by the growth process at initial state of transformation while at final stage nucleation contributes into formation of nanocomposite structure. In order to describe thenanocrystallization kinetics of the Al- based glasses the analytical kinetic equations in the frames of Kolmogorov-Johnson-Mehl-Avrami model have been proposed and the effective volume diffusion coefficient values which govern the diffusion-limited growth nanocrystals have been determined. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kurgan N.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | Karbivskyy V.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | Kasyanenko V.,Vinnytsia National Technical University
Nanoscale Research Letters | Year: 2015

Atomic force microscopy, infrared spectroscopy and NMR studied morphological and physicochemical properties of calcium hydroxyapatite powders produced by changing the temperature parameters of synthesis. Features of morphology formation of calcium hydroxyapatite nanoparticles with an annealing temperature within 200°C to 1,100°C were determined. It is shown that the particle size of the apatite obtained that annealed 700°C is 40 nm corresponding to the particle size of apatite in native bone. The effect of dimension factor on structural parameters of calcium hydroxyapatite is manifested in a more local symmetry of the PO4 3− tetrahedra at nanodispersed calcium hydroxyapatite. © 2015, Kurgan et al.; licensee Springer.

Tkatch V.I.,Aa Galkin Donetsk Institute For Physics And Engineering | Nosenko V.K.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | Moiseeva T.N.,Aa Galkin Donetsk Institute For Physics And Engineering | Rassolov S.G.,Aa Galkin Donetsk Institute For Physics And Engineering | And 3 more authors.
Journal of Non-Crystalline Solids | Year: 2015

Thermal stability, structural changes and nanocrystallization kinetics of the Fe80B14Si6 and Fe45Ni19.4Co8.5Cr5.7Mo1.9B14Si5.5 amorphous alloys under continuous heating and isothermal annealings as well as the changes of microhardness caused by the phase transitions have been experimentally studied by a combination of X-ray diffraction analysis, differential scanning calorimetry, by measurements of electrical resistance and microhardness. The partial replacement of Fe in the Fe80B14Si6 alloy by a number of transition metals results in lowering of the onset crystallization temperature, facilitating the nanocrystal forming tendency, and enhancement of the microhardness values of the samples in the non-equilibrium structural states. The temperature dependencies of effective diffusion coefficients governing nanocrystallization are determined by approximation of the experimentally measured changes of the α-Fe nanocrystal sizes and the kinetic curves of nanocrystallizationwithin the appropriate analytical models. The essentially lower thermal stability f the Fe45Ni19.4Co8.5Cr5.7Mo1.9B14Si5.5 amorphous alloy comparedwith that of Fe80B14Si6 is associated with about two orders of magnitude lower effective diffusivity at the onset crystallization temperatures. From comparison of the rates of growth of α-Fe nanocrystals and their numbers of volumedensity in nanocomposite structures, it is suggested that the thermal stability of the former amorphous alloy is limited by slow diffusion-limited growth, while that of the latter one is controlled by nucleation. © 2015 Elsevier B.V. All rights reserved.

Karbivskyy V.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | Karbivska L.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine | Artemyuk V.,Gv Kurdymov Institute For Metal Physics Of The Nas Of Ukraine
Nanoscale Research Letters | Year: 2016

The formation mechanisms of Ag- and Au-ordered structures on single-crystal silicon (Si) (111) and Si (110) surfaces were researched using high-resolution scanning tunneling microscopy method. It was shown that different patterns of self-assembled nanostructures with very precise and regular geometric shapes can be produced by controlling process parameters of thermal metal spraying on the substrate. The surfaces of nanorelieves at each stage of deposition were researched, and the main stages of morphological transformation were fixed. Self-ordered hexagonal pyramid-shaped nanostructures were formed at thermal deposition of gold on the Si (111), whereas only monolayer hexagonal formation could be observed on the plane Si (110). Gold monolayer flake nanostructures were obtained under certain technological parameters. Atomically smooth Ag film cannot be obtained on the Si (111) surface by means of thermal spraying at room temperature. The formation of two-dimensional (2D) clusters takes place; heating of these clusters at several hundred degrees Celsius leads to their transformation into atomically smooth covering. The weak interaction between Ag multilayer coatings and substrate was established that allows to clear crystal surface from metal with reproduction of the reconstructed Si (111) 7 × 7 surface by slight warming. The offered method can be used for single-crystal surface protection from destruction. © 2016, Karbivskyy et al.

Discover hidden collaborations