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In this paper, rotation properties of suspended particles under an external rotating electric field (EREF) are investigated. Based on the re-distribution of surface-induced charges on moving particles, the torque exerting on particles by EREF is derived analytically. Furthermore, for the sol suspended in Newtonian fluid, the angular velocity of the rotating particle is formulated by the EREF and the dielectric constants of the particle and matrix. The result shows that the angular velocity of particles depends on the angular velocity of EREF, and is proportional to the square of EREF strength. The maximum angular velocity of rotating particles is reached if the angular velocity of EREF is equal to the reciprocal of the relaxation time of the induced charge. [ABSTRACT FROM AUTHOR]

The perturbation method is developed to investigate the effective nonlinear dielectric response of Kerr composites when the external ac and dc electric field is applied. Under the external ac and dc electric field E[sub app]=E[sub a](1+sin ωt), the effective coupling nonlinear response can be induced by the cubic nonlinearity of Kerr nonlinear materials at the zero frequency, the finite basic frequency ω, the second and the third harmonics, 2ω and 3ω, and so on. As an example, we have investigated the cylindrical inclusions randomly embedded in a host and derived the formulas of the effective nonlinear dielectric response at harmonics in dilute limit. For a higher concentration of inclusions, we have proposed a nonlinear effective-medium approximation by introducing the general effective nonlinear response. With the relationships between the effective nonlinear response at harmonics and the general effective nonlinear response, we have derived a set of formulas of the effective nonlinear dielectric responses at harmonics for a larger volume fraction. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Recent experiments on electrorheological effects provide evidence that the rotation of particles weakens the induced electric forces between dielectric particles. To study the induced electric force exerted on rotating particles phenomenologically, we establish a differential equation to describe the relaxation process of the surface polarized charge distribution on rotating particles in an electrorheological fluid. In the case of a uniformly rotating particle, a general solution to the relaxation equation for the polarized charge is obtained. The surface charge distribution of a two-particle system consisting of a particle at rest and a uniformly rotating particle is calculated. Based on the Green's function approach, we evaluate the electric potential in both the host and the rotating particle. A formula relating the angular velocity of rotating particle to the induced electric force on the particle is then derived. [ABSTRACT FROM AUTHOR]

Studies the periodic composite materials with contact resistance on the inclusion surface. Equations and boundary conditions; Information on the generalized Rayleigh identity; Temperature field in a periodic composite with contact resistance.

A U(VI) mononuclear coordination complex [UO2(a4-ptz)2·(H2O)3] (1) and a Zn(II) 1-D coordination polymer [Zn(a4-ptz)2·(H2O)2]·2H2O (2) have been synthesized with 5-[N-acetato(4-pyridyl)]tetrazolate (a4-ptz) as ligand. Complex 1 has a slightly distorted pentagonal bipyramid around each U center. Complex 2 is octahedral with four a4-ptz and two water ligands. Each Zn center is linked by carboxylate-O(1) and tetrazolate-N(2) of a4-ptz forming a 1-D polymeric chain. Complexes 1 and 2 are self-assembled to form 3-D supramolecular structures through hydrogen bonds. The luminescence properties of 1 and 2 were investigated at room temperature in the solid state. The results suggest that 1 and 2 may be useful as photoactive materials. [ABSTRACT FROM AUTHOR]

The electric potential in a granular system consisting of spherical inclusions in the presence of an external applied electric field is studied in detail within the framework of the Rayleigh identity. The effects of induced charges on the inclusions are taken into account explicitly. The method, in principle, includes the effects of all multipoles. The method is applied to study the interaction between two inclusions. The standard form of interaction between inclusions widely used in studying ER fluids is recovered as an approximation of our general approach. We then apply the method to a chain of inclnsions. Analytic expressions for the electrostatic energy per inclusion and the electric field are obtained for the case in which the chain is parallel to the applied field. Our result reduces to the form used in the literature when appropriate approximation is taken. The method is further extended to study the interaction between chains of inclusions. An approximate expression is obtained for the force between two chains of inclusions. Our approach provides a rigorous framework for determining the interaction between inclusions and chains of inclusions to arbitrary accuracy. [ABSTRACT FROM AUTHOR]