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Effective complex permittivity and continuum percolation analysis of two-phase composite media


Using ab initio finite-element (FE) calculations we study the dielectric properties of the continuum (off-lattice)-percolation system consisting of two-dimensional equilibrium distributions of randomly distributed circular and partially penetrable disks (or parallel, infinitely long, identical, partially penetrable circular cylinders) throughout a host matrix. Theoretical investigations of the (relative) effective complex permittivity ;5;=;5;''-i;5;' were conducted a hybrid modeling that combine standard Metropolis Monte Carlo (MC) algorithm and continuum-electrostatics equations which are solved by finite element calculations. We present the details of the ;5;dependence on surface fraction =5;2 of the disks, permittivity contrast between the two phases and arbitrary degree of impenetrability ;B; (0ʧD; ;B; ʧD;1), for wide ranges of these parameters. Careful evaluation of the critical exponents s and t governing the power-law behavior of ;5;'' and ;5;' respectively, near the percolation threshold, are used to address controversial or unresolved issues, related to the underlying physics of the classical percolation model. Our results, corresponding to different values of ;B; in the range 0ʧD; ;B; ʧD; 0.9 and for a wide range of phase''s permittivity ratios, indicate that s and t can differ from the universal values, i.e. s=t Ȧ1; 1.3 , characterizing the continuum percolation phenomena of statistically isotropic distributions of disks in a plane. As the distance to =5;2c is decreased, ;5;'' and ;5;' display a smooth transition from a power-law dependence, which is well fit by the standard percolation expression, to a plateau regime. We associate the plateau with finitesize effects and the short-range multipolar interactions localized in disk clusters. The radial distribution function (RDF) results are consistent with -nthe notion that larger area fractions lead to an increase in the distance over which one disk influences another via excluded volume effect. Furthermore, we perform a quantitative test of the McLachlan (TEPPE) equation by comparing its prediction of the effective permittivity to the simulation results obtained on systems with overlapping disks (0ʧD; ;B;ʧD; 0.9). We find that the analytic equation presented by McLachlan is consistent with FE-MC simulations only for =5;2=5;2c can be attributed to a poor representation of the various degrees of disk aggregation present in the equilibrium distributions where increased aggregation results in an enhanced multipolar interaction.......

【作者名称】: Myroshnychenko, V., Brosseau, C.
【作者单位】: Instituto de Óptica - CSIC Serrano 121, 28006 Madrid, Spain
【关 键 词】: Effective complex permittivity and continuum percolation analysis of two-phase composite media
【期刊名称】: Dielectrics and Electrical Insulation, IEEE Transactions on
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 109,773,657
【摘要长度】: 2,528
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