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Abstract. Using the Rouse-Fowler (RF) model this work studies the radiation-induced electrical conductivity of a polymer nanocomposite material with spherical nanoparticles against the intensity and exposure time of gamma-ray, concentration and size of nanoparticles. The research has found the energy distribution of localized statesinduced by nanoparticles. The studies were conducted on polymethylmethacrylate (PMMA) with CdS nanoparticles. IntroductionNanocomposite materials are materials formed by inclusion of nanoparticles into some matrix material. As a result, we can create a new functional material with unique electro physical properties. PMMA+CdS or CdSe nanocomposite allows creation of new types of photo galvanic and optoelectronic devices [1][2]. It is important to consider the possibility of using these devices under increased radiation (space, nuclear engineering, etc.). Therefore, the study of the nanocomposite radiation resistance is an important and relevant task [3]. Particular attention is given to spherical semiconductor nanoparticles such as CdS or CdSe due to the fact that their fluorescence band covers whole visible, near-IR and near-UV bands depending on the particle size. It is known that such size dependent properties are related to quantum confinement effects that are more pronounced with the smaller nanoparticle size. Thus nanocomposites with the nanoparticle size less than 10 nm possess the most interesting electrophysical properties. The maximal realization of electrophysical properties of CdS and CdSe nanoparticles requires their isolation from each other, that is why the nanoparticle concentration normally does not exceed 10 vol.%.Using the Rouse-Fowler (RF) model, this work studies the radiation-induced electrical conductivity of the polymer nanocomposite exposed to gamma-rays. According to works [4][5][6], phenomena related to the radiation-induced electrical conductivity of polymers are best described by the Rouse-Fowler model. There are analytic and numerical solutions [7][8][9][10][11] for the model variations where either the spectrum of localization centers (traps) in the bandgap has only one or two states or the distribution of trap energy states follows the exponential law. Nanocomposite materials are characterized by existence of additional centers of localization in the bandgap. The energy distribution of these centers depends on the shape, size and concentration of nanoparticles. Thus the need to describe electrophysical properties of nanocomposites requires the RF model generalization for a certain energy distribution of localization centers in the bandgap.
Abstract. Using the Rouse-Fowler (RF) model this work studies the radiation-induced electrical conductivity of a polymer nanocomposite material with spherical nanoparticles against the intensity and exposure time of gamma-ray, concentration and size of nanoparticles. The research has found the energy distribution of localized statesinduced by nanoparticles. The studies were conducted on polymethylmethacrylate (PMMA) with CdS nanoparticles. IntroductionNanocomposite materials are materials formed by inclusion of nanoparticles into some matrix material. As a result, we can create a new functional material with unique electro physical properties. PMMA+CdS or CdSe nanocomposite allows creation of new types of photo galvanic and optoelectronic devices [1][2]. It is important to consider the possibility of using these devices under increased radiation (space, nuclear engineering, etc.). Therefore, the study of the nanocomposite radiation resistance is an important and relevant task [3]. Particular attention is given to spherical semiconductor nanoparticles such as CdS or CdSe due to the fact that their fluorescence band covers whole visible, near-IR and near-UV bands depending on the particle size. It is known that such size dependent properties are related to quantum confinement effects that are more pronounced with the smaller nanoparticle size. Thus nanocomposites with the nanoparticle size less than 10 nm possess the most interesting electrophysical properties. The maximal realization of electrophysical properties of CdS and CdSe nanoparticles requires their isolation from each other, that is why the nanoparticle concentration normally does not exceed 10 vol.%.Using the Rouse-Fowler (RF) model, this work studies the radiation-induced electrical conductivity of the polymer nanocomposite exposed to gamma-rays. According to works [4][5][6], phenomena related to the radiation-induced electrical conductivity of polymers are best described by the Rouse-Fowler model. There are analytic and numerical solutions [7][8][9][10][11] for the model variations where either the spectrum of localization centers (traps) in the bandgap has only one or two states or the distribution of trap energy states follows the exponential law. Nanocomposite materials are characterized by existence of additional centers of localization in the bandgap. The energy distribution of these centers depends on the shape, size and concentration of nanoparticles. Thus the need to describe electrophysical properties of nanocomposites requires the RF model generalization for a certain energy distribution of localization centers in the bandgap.
Irradiation of solid-state targets by a high-power beam of accelerated charged particles (electrons or ions) with energy-flux density >t 107 W/cm 2 is accompanied by generation of compression and expansion waves in the radiation-free part of the material due to intense warming up of some volume of the target caused by stoppage of particles. Wave propagation over a solid body causes deformations leading to the formation of various defects [1][2][3][4], to changes in the mechanical properties of the material, and even to failure [5].The system of equations describing the generation and propagation of elastoplastic waves in a material, which are induced by a charged-particle beam, includes a kinetic equation for high-velocity charged particles, equations of continuum mechanics, and a wide-range equation of state.Experience on the numerical solution of this problem has shown that many calculations deal with the equations of continuum mechanics. To simulate the effect of high-power beams of charged particles on a material, these equations are solved by various methods: Leshkevich and Khalikov et al. in [6, 7] used the method of macroparticles [8], Akkerman et al. in [9, 10] used the Godunov method [11], and Val'chuk in [12] used the Wilkins method [13].Application of the method of macroparticles to the problem considered here involves two difficulties. First, this method is unstable for weak flows. This does not make it possible to simulate the effect of the beams that are of technological interest and, second, in the free-surface problems the free surfaces are difficult to approximate.The main drawback of the Godunov method is a strong smoothing of the solution in the vicinity of a contact discontinuity.The method for solving the equations of continuum mechanics which was developed by Wilkins [13] avoids the drawbacks listed above, although there are some difficulties in its application due to the use of Lagrangian variables to simulate strong deformations of the material.One more problem, which is common for all schemes containing artificial viscosity, is to select a value of the coefficient of artificial viscosity. Numerical experiments show that with an acceptable smoothness of the solution, variation in this coefficient changes the shock-wave amplitude by 10-20%. In addition, in calculation of flow of a medium that is in the liquid-gas equilibrium region, the schemes with artificial viscosity become unstable because of a large decrease in the sound velocity (by 2-3 orders of magnitude).In the present paper, we find analytical solutions of the equations of continuum mechanics for a material component by means of which the motion of the entire system is simulated. In some cases, the use of the analytical solutions obtained makes it possible to increase the time step of calculation. This increase can be considerable in comparison to the time step found from the Courant condition, as in the example below.The equations are solved in Lagrangian variables. The algorithm proposed for reconstruction of the Lagrangian ...
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