Изучение свойств сплава золото-железо в макро- и нанокристаллических состояниях в различных P-T-условиях

For a disordered fcc-Au-Fe substitution alloy, the parameters of the Mie–Lennard-Jones pairwise interatomic potential are determined. Based on these parameters, the concentration dependencies of lattice properties for the macrocrystal of this alloy are calculated. Calculations of 20 properties of macrocrystals fcc-Au, fcc-Fe and fcc-Au0.5Fe0.5 are showed good agreement with experimental data. Using the RP-model of the nanocrystal, the state equation P(v, T; N) and baric dependences of both lattice and surface properties of the fcc-Au0.5Fe0.5 alloy are calculated. Calculations were performed at temperatures T = 100, 300 and 500 K for both a macrocrystal (N = Macro) and a cubic nanocrystal with N = 306 atoms. It is shown that with an isothermal-isobaric (P = 0) decrease in the size of a nanocrystal, its the Debye temperature, elastic modulus, and specific surface energy decrease, while its the specific volume, thermal expansion coefficient, specific heat capacity, and Poisson's ratio increase. At low temperatures in a certain pressure region, the specific surface energy increases at an isothermal-isobaric decrease in the number of atoms in the nanocrystal. As the temperature increases, this pressure region disappears.

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Зависимость поверхностной энергии от температуры и давления для макро- и нанокристалла

Физика твердого тела ◽

10.21883/ftt.2021.09.51279.080 ◽

2021 ◽

Vol 63 (9) ◽

pp. 1415

Author(s):

М.Н. Магомедов

Keyword(s):

High Pressures ◽

Interatomic Potential ◽

Nanocrystal Size ◽

Surface Shape ◽

Thermoelastic Properties ◽

Specific Surface Energy ◽

Lennard Jones ◽

Different Temperatures ◽

Derivatives Of ◽

Good Agreement

Based on the RP-model of a nanocrystal, an analytical method is developed for calculating the specific surface energy (), isochoric and isobaric derivatives of the  function with respect to temperature, and isothermal derivatives of the  function with respect to pressure and density. It is shown that the method is applicable for both macro-and nanocrystals with a given number of atoms and a certain surface shape. To implement this method, the parameters of the Mie–Lennard-Jones paired interatomic potential were determined in a self-consistent way based on the thermoelastic properties of the crystal. The method was tested on macrocrystals of 15 single-component substances: for 8-FCC crystals (Cu, Ag, Au, Al, Ni, Rh, Pd, Pt) and for 7-BCC crystals (Fe, V, Nb, Ta, Cr, Mo, W). The calculations were made at different temperatures and showed good agreement with the experimental data. Using the example of FCC-Rh, the change in surface properties with a decrease of the nanocrystal size along the isotherms of 10, 300, 2000 K is studied. It is shown that at high pressures and low temperatures, there is a region where the  function increases at an isomorphic-isothermal-isobaric decrease in the nanocrystal size. As the temperature increases, this area disappears.

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Размерная зависимость упругих свойств нанокристалла аргона

Физика твердого тела ◽

10.21883/ftt.2019.01.46905.175 ◽

2019 ◽

Vol 61 (1) ◽

pp. 148

Author(s):

М.Н. Магомедов

Keyword(s):

Elastic Modulus ◽

Surface Energy ◽

Specific Surface ◽

Debye Temperature ◽

State Equation ◽

Optimal Shape ◽

Nanocrystal Size ◽

Specific Surface Energy ◽

Size And Shape ◽

Gruneisen Parameters

AbstractThe state equation ( P ) and isothermal elastic modulus ( B ) are calculated for argon macro- and nanocrystals at T = 10 K using in the framework the RP(vac)-model of nanocrystal. The isochoric and isobaric (at P = 0) dependences of the Debye temperature (Θ), of the first (γ) and second ( q ) Grüneisen parameters, as well as the specific surface energy (σ), B and B '( P ) = (∂ B /∂ P )_ T , are studied as the functions of size and shape of the nanocrystal. As shown, the isothermally isobaric decrease in nanocrystal size is accompanied by a decrease in functions Θ, q , σ, B and B '( P ) and by an increase in the γ parameter. However, the elastic modulus rises in the case of the isothermally isochoric decrease in the nanocrystal size. When the nanocrystal deviates from its most energetically optimal shape (a cube for the RP(vac)-model), the size dependences of these functions become more noticeable.

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BARIC DEPENDENCE OF LATTICE PROPERTIES FOR DIAMOND

IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA ◽

10.6060/tcct.20165909.14y ◽

2018 ◽

Vol 59 (9) ◽

pp. 57

Author(s):

Makhach N. Magomedov

Keyword(s):

Experimental Data ◽

Thermal Expansion ◽

Elastic Modulus ◽

Thermal Expansion Coefficient ◽

Expansion Coefficient ◽

Interatomic Potential ◽

State Equation ◽

Relative Volume ◽

Lennard Jones ◽

Good Agreement

Based on the pairwise interatomic potential of Mi-Lennard-Jones and the Einstein's model of crystal the state equation P(V/V0, T) and the baric dependencies of the lattice properties for diamond were obtained. The calculations were performed along two isotherms: T = 300 and 3000 K and until to P = 10000 kbar (i.e. until to the relative volume V/V0 = 0.5). The baric dependencies for the following properties were obtained: isothermal elastic modulus, isochoric and isobaric heat capacities and thermal expansion coefficient. Good agreement with experimental data was obtained.

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