Charge, voltage, and work-conversion formulas for magnetoelectric laminated composites

Abstract

A novel analytical model for magnetoelectric (ME) laminate composites made of piezoelectric (PE) and piezomagnetic (PM) phases is proposed. The multiphysics equations are applied to all four possible laminate configurations (TT, LT, TL, and LL), with appropriate boundary conditions. Closed form, explicit formulas are derived for the calculation of the intrinsic ME charge coefficient, ME voltage coefficient, and ME coupling factor as a function of material properties of both phases and the PM volume fraction. The predicted ME voltage coefficient is in agreement with previous work and experimental data. A new approach is proposed to take into account the conductivity of the PM phase resulting in calculated ME charge coefficients within 30% of experimental data, which is a major departure from the available approaches that either require to impose an additional constraint on the model or simply ignore the conductivity of the PM phase. To assess the conversion of magnetic work into electric work, a novel approach is developed to calculate the ME coupling factor in closed form by using the calculated properties of the ME composite structure, thus avoiding the equivalent circuit assumption, and furthermore novel coupling factor formulas are developed for all four polarization/magnetization configurations and taking into account the strain coupling in both inplane directions. Using actual material properties, conclusions are drawn regarding the optimal configuration and PM volume fraction necessary to achieve maximum charge, voltage, and work conversion.