Modeling of ferroelectric-ferromagnetic composites to improve magnetoelectric coupling and durability

摘要

The coupling of magnetic and electric fields due to the constitutive behavior of a material is commonly denoted as ME-effect. The latter is only observed in a few crystal classes exhibiting a very weak coupling which can hardly be exploited for technical applications. Much larger coupling coefficients are obtained in so called multiferroic composite materials, where ferroelectric and ferromagnetic constituents are embedded in a matrix. The ME-effect is then induced by the strain of the matrix converting electrical and magnetic energies based on the ferroelectric and magnetostrictive effects. In this paper, the theoretical background of nonlinear constitutive multifield behavior as well as the Finite Element implementation are presented. Nonlinear material models describing the magneto-ferroelectric behavior are presented. On this basis, the poling process in the ferroelectric phase is simulated and resulting effects are analyzed. Numerical simulations in general focus on the prediction of ME coupling coefficients and residual stresses going along with the poling process. Numerical homogenization, here, is a useful means to supply effective properties.