Аннотация:The effect of a uniform magnetic field on the permittivity of magnetorheological elastomers (MRE) has been simulated. The effective permittivity of MRE filled with conductive particles was shown to be strongly dependent on the applied magnetic field (magnetodielectric effect, MDE). The model has been developed to give the qualitative explanation of the experimental results obtained earlier in our group – we studied the change of the capacity of plane capacitor filled with magnetorheological elastomers (magnetocapacitance effect), and observed the increase of the effective dielectric permittivity of MRE based on Fe, Fe3O4 and NdFeB [1].
Here we present results of the computer simulation of magnetocapacitance effect. The influence of particles concentration, orientation of magnetic field, and form of the sample on the studied effect was investigated. The behavior of spherical magnetic particles uniformly distributed in elastic matrix under the applied magnetic field was simulated. We considered the dipole-dipole interactions, the interaction of particles magnetic moments with external field and elastic stresses caused with matrix deformations. It was shown, that particles tend to form a chain-like structures when magnetic field is applied. The displacement of particles and, therefore, the value of magnetocapacitance effect is dependent on the elastic properties of matrix and intensity of magnetic field. The dependence on magnetic field strength was shown to have hysteresis type. It also was shown, that effect value strongly depends on thickness of sample.
The results of modeling are in good qualitative agreement with experimental data [1].
The observed field-induced phenomena evidence the attractiveness of MREs as novel promising materials in family of composite multiferroics.