Melting Behaviour of Fractal-Shaped Nanoparticles (the Example of Si–Ge System)

Shishulin, A. V.; Fedoseev, V. B.; Shishulina, A. V.

doi:10.1134/s1063784219090172

Cited by 11 publications

(15 citation statements)

References 38 publications

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“…High values of shape coefficient k could be obtained, for example, in the case of porous materials where the pores have the shapes similar to simple non-spherical geometric structures (for example, k=1.49 for a tetrahedron, k=1.52 for a cone, k=3.20 for a star icosahedron (an icosahedron with a tetrahedron at each face)) or structures extended in one direction (for example, values k>2.00 correspond to oblate spheroids with aspect ratio a/b>5 or to prolate spheroids with a/b>3). Moreover, high surface-to-volume ratios are also characteristic for pores of complicated and irregular shapes, in order to take into account their morphology, the notion of fractal geometry is often used [29,30,[38][39][40][41][42]. According to the approach suggested by us in [30,[40][41][42], the shape of a pore can be characterized by its fractal dimension D which correlates its volume V and surface area A:…”

Section: A Cohesive Energy-based Model For Magnetic Phase Transitions In Mesoporous Mediamentioning

confidence: 99%

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2021

Eurasian phys. tech. j.

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In this paper, we have shown how the presence of pores and pore morphology influence on magnetic phase transition temperatures in mesoporous ferromagnetic materials. Model calculations have demonstrated the possibility to obtain macroscopic mesoporous samples with notably reduced Curie temperatures which is also further depressed in the case the pore morphology is more complicated. The results have been obtained on the basis of the experimentally verified correlation between the Curie temperature and cohesive energy of the material and illustrated using the examples of pure mesoporous iron, nickel and cobalt while pore morphology has been determined by the methods of fractal geometry. Several practical applications of mesoporous materials with tuned values of the Curie temperature have also been discussed in the final section.

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Section: A Cohesive Energy-based Model For Magnetic Phase Transitions In Mesoporous Mediamentioning

confidence: 99%

Untitled

2021

Eurasian phys. tech. j.

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“…Следует отметить, что полученные ранее оценки [1,10,17,[20][21][22]28,33] для ряда простых неорганических систем и водных растворов с органическим компонентом позволяют ожидать заметных изменений температур фазовых переходов и фазовых составов при модификации геометрических параметров системы, как правило, лишь в случаях, когда характерный размер системы не превышает сотен нанометров. Как показано выше (рис.…”

Section: результаты моделирования и обсуждениеunclassified

“…Расслаивание жидких растворов в порах зачастую приводит к образованию структуры " ядро-оболочка" (core-shell) [1,2,31,32]. Форма поры, определяющаяся степенью деформации матрицы, может быть охарактеризована параметрически с использованием различных подходов [1,2,10,[20][21][22][33][34][35], включая методы фрактальной геометрии [1,10,21,22,33].…”

Section: Introductionunclassified

Расслаивающиеся Полимерные Растворы В Микроразмерных Порах: Фазовые Переходы, Индуцированные Деформацией Пористого Материала

Шишулин¹,

Федосеев²

2020

Журнал Технической Физики

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The influence of pore morphology on phase equilibria in stratifying polymer solutions within porous matrices has been simulated by means of equilibrium chemical thermodynamics. Using the example of liquid stratifying polybutadiene-polystyrene oligomer mixtures, we have shown that deformation of a matrix which influences on pore shapes, determines mutual solubilities of components within a pore, equilibrium volume ratios of co-existing phases and their thermodynamic stability. The change in the geometric characteristics of a pore is simulated in general by introducing a parameter corresponding to the degree of deviation of the shape of the pore walls from the spherical one. The dependences of mutual solubilities of components on pore volume within pores of different shapes are different which has been explained by the existence of several mechanisms of lowering the free energy of the system. Severe deformations of a matrix lead to suppressing the stratification in microsized pores while every composition up to the equimolar one becomes thermodynamically stable.

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“…The data about the peculiarities of phase equilibrium under conditions of limited geometry or while moving from massive objects to small‐size samples look as no less important. [ 1–5 ] It often happens, that size effects in such structures cause exceptional properties that are demanded, particularly, in technologies of nanocomposite materials [ 6,7 ] to increase the wear resistance and antifriction properties of protective coatings. [ 8,9 ]…”

Section: Introductionmentioning

confidence: 99%

“…The data about the peculiarities of phase equilibrium under conditions of limited geometry or while moving from massive objects to small-size samples look as no less important. [1][2][3][4][5] It often happens, that size effects in such structures cause exceptional properties that are demanded, particularly, in technologies of nanocomposite materials [6,7] to increase the wear resistance and antifriction properties of protective coatings. [8,9] A method for studying phase diagrams in alloy films, which allows to visualize the phase diagram of the studied system on the single sample and to trace its evolution under the change in the film thickness was suggested in refs.…”

Section: Introductionmentioning

confidence: 99%

Phase Diagram of In–Pb Alloy in Condensed Films

Дукаров

Petrushenko

Samsonik

et al. 2020

Physica Status Solidi (a)

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Two‐layer In–Pb films with a thickness from 50 to 200 nm, which are obtained by the method of sequential vacuum condensation, are used to study the phase diagram in this binary system. In–Pb films with a smooth composition change (0–100%) and annealing temperature (20–400 °C) are obtained within a single experimental cycle. The original method of variable composition and variable state is used. With this method of obtaining, the boundaries are observed on the substrate separating different regions of the film. X‐ray diffraction studies show that these areas correspond to different phase states of the sample and visualize the phase diagram of a binary system. The In–Pb phase diagram observed in the films generally corresponds to that for bulk samples. With an increase in the annealing temperature, the dispergation of the films intensifies. Below the liquidus temperature, the films consist of inhomogeneous in composition particles of irregular shape. Above the liquidus line, the films consist of homogeneous islands in the form of a spherical segment. Their size distribution is unimodal with a maximum; the position of which in a wide range does not depend on the concentration of the components.

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Melting Behaviour of Fractal-Shaped Nanoparticles (the Example of Si–Ge System)

Cited by 11 publications

References 38 publications

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Расслаивающиеся Полимерные Растворы В Микроразмерных Порах: Фазовые Переходы, Индуцированные Деформацией Пористого Материала

Phase Diagram of In–Pb Alloy in Condensed Films

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