Study of the kinetics of space charge formation in colloidal magnetic nanoparticles in liquid dielectrics

Erin, K. V.

doi:10.3103/s1068375517040044

Cited by 3 publications

(10 citation statements)

References 15 publications

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“…The main idea of constructing such a model is to study the question of the possibility of the occurrence of autowave motion due to the recharging of MF particles near the electrodes or in the regions of localization of the space charge. The model is described by a boundary-value problem, which consists of a research area (Figure 6), a system of equations (6)(7)(8)(9)(10)(11)(12), and initial and boundary conditions (13)(14)(15)(16)(17)(18)(19)(20). When constructing the model, the following assumptions were made:…”

Section: Basic Equations Of the Modelmentioning

confidence: 99%

“…In this work, we investigate the liquid "magnetite in kerosene" with oleic acid as a stabilizer, which is a weakly conducting dielectric with a conductivity of about 10 −7 Ohm −1 /m −1 . The passage of the electric current is provided by impurity ions (with a concentration of about 10 20 m −3 ) and low-mobile colloidal particles [12,13]. This process is accompanied by a disturbance in the equilibrium between the reactions of the dissociation-recombination of impurity ions.…”

Section: Introductionmentioning

confidence: 99%

“…This process is accompanied by a disturbance in the equilibrium between the reactions of the dissociation-recombination of impurity ions. As a result of this disturbance, the nonequilibrium regions of the space charge appear at the electrodes [12][13][14]. Charged electrodes attract colloidal particles of opposite charge sign to themselves and form near-electrode layers-colloidal systems with a high concentration of magnetic particles.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Theoretical Study of an Autowave Process in a Magnetic Fluid

Chekanov

Коваленко

2022

IJMS

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Magnetic fluid (MF) is a colloidal system consisting of ferromagnetic particles (magnetite) with a diameter of ~10 nm suspended in a dispersion medium of a carrier fluid (for example, kerosene). A distinctive feature of magnetic fluid is the fact that when an electric field is applied to it using two electrodes, thin layers consisting of close-packed particles of the dispersed phase are formed in the regions near the surface of both electrodes. These layers significantly affect the macroscopic properties of the colloidal system. In this work, the interpretation of the near-electrode layer is for the first time given as a new type of liquid membrane, in which the particles of the dispersed phase become charged with the opposite sign. On the basis of experimental studies, we propose a physicochemical mechanism of the autowave process in a cell with a magnetic fluid. It is based on the idea of oppositely recharging colloidal particles of magnetite in a liquid membrane. A mathematical model of an autowave process, which is described by a system of coupled partial differential equations of Nernst–Planck–Poisson and Navier–Stokes with appropriate boundary conditions, is proposed for the first time. One-dimensional, two-dimensional, and three-dimensional versions of the model are considered. The dependence of the frequency of concentration fluctuations on the stationary voltage between the electrodes was obtained, and the time of formation of a liquid membrane was estimated. Qualitative agreement between theoretical and experimental results has been established.

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Section: Basic Equations Of the Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental and Theoretical Study of an Autowave Process in a Magnetic Fluid

Chekanov

Коваленко

2022

IJMS

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“…Подвижность частицы b = ◊ -5 10 9 м 2 В -1 с -1 была определена по формуле, представленной в [21]. Тогда скорость частицы в объеме ячейки равна n = ◊ -5 10 4 м•с -1 .…”

Section: физическая модель автоколебаний частиц в ячейке с магнитной жидкостьюunclassified

“…Расчет показал, что при скачке потенциала между электродами Dj = 5 В, расстоянии между электродами d = ◊м 2 В -1 с -1[13] ширина области объемного заряда равна d  4 10 7 ◊м. Значение напряженности электрического поля в приэлектродной области изменяется согласно уравнению Пуассона из-за наличия объемного заряда плотностью r[21].По данным работы[22] характерное время образования объемного заряда для жидкости средней концентрации магнетита (3.4 об.%) для образцов на основе керосина составляет величину порядка 0.05 с. Оценка времени образования объемного заряда в электрическом поле требует учета миграционной поляризации частиц магнетита, которая в рассматриваемом нами случае может быть описана в рамках теории Максвелла-Вагнера. Время масвелл-вагнеровской поляризации (2) много меньше времени образования объемного заряда:…”

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Experimental study and mathematical modelling of self-oscillation at the electrode-magnetic fluid interface in an electric field

Chekanov

Кириллова

Коваленко

et al. 2021

kcmf

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The article describes a mathematical model of self-oscillation in the form of a boundary value problem for a nonlinear system of partial differential equations, with a numerical solution. The numerical results were compared to the experimental data to confirm the adequacy of the model. The model uses the classical system of differential equations of material balance, Nernst-Planck and Poisson equations without simplifications or fitting parameters. The aim of the article was to study the parameters of concentration self-oscillation in a layer of the dispersed phase particles of magnetic fluid at the interface with an electrode in an electric field. For this purpose, we developed a mathematical model, the consistency of which wasconfirmed by the corresponding physical mechanism.As a result of numerical experiments, we found the critical value of the potential jump after which self-oscillation began. We also determined the oscillation growth period and other characteristics of the process. We developed software called AutoWave01 with an intuitive user interface and advanced functionality for the study of self-oscillation in a thin layer of magnetic colloid.

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Electro-Orientation of Silver Nanowires in Alternating Fields

et al. 2018

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In this work, we analyze the orientation of silver nanowires immersed in aqueous solutions, under the effect of alternating electric fields in a broad frequency range covering from a few Hz to several MHz. The degree of orientation is experimentally determined by electro-optical techniques, which present the advantage of measuring multiple particles at the same time. In the electro-orientation spectrum, we observe frequency dispersion in the kHz range and provide a theoretical explanation for this behavior: at high frequencies, charge separation in the nanoparticles leads to a large induced dipole responsible for strong orientation. On the other hand, at low frequencies, redistribution of the ions in solution gives rise to an induced double layer that screens the dipolar fields, and as a consequence, the degree of orientation decreases. Moreover, we measure the transient response when the electric field is switched off, from which the size distribution of the polydisperse sample is obtained. The results match those given by electron microscopy determinations.

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Study of the kinetics of space charge formation in colloidal magnetic nanoparticles in liquid dielectrics

Cited by 3 publications

References 15 publications

Experimental and Theoretical Study of an Autowave Process in a Magnetic Fluid

Experimental and Theoretical Study of an Autowave Process in a Magnetic Fluid

Experimental study and mathematical modelling of self-oscillation at the electrode-magnetic fluid interface in an electric field

Electro-Orientation of Silver Nanowires in Alternating Fields

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