Abstract
In previous works, most of them employ a linear constitutive model to describe magnetocapacitance (MC) effect in magnetoelectric (ME) composites, which lead to deficiency in their theoretical results. In view of this, based on a nonlinear magnetostrictive constitutive relation and a linear piezoelectric constitutive relation, we establish a nonlinear model for MC effect in PZT-ring/Terfenol-D-strip ME composites. The numerical results in this paper coincide better with experimental data than that of a linear model, thus, it’s essential to utilize a nonlinear constitutive model for predicting MC effect in ME composites. Then the influences of external magnetic fields, pre-stresses, frequencies, and geometric sizes on the MC effect are discussed, respectively. The results show that the external magnetic field is responsible for the resonance frequency shift. And the resonance frequency is sensitive to the ratio of outer and inner radius of the PZT ring. Moreover, some other piezoelectric materials are employed in this model and the corresponding MC effects are calculated, and we find that different type of piezoelectric materials affect the MC effect obviously. The proposed model is more accurate for multifunction devices designing.
Highlights
INTRODUCTIONThe controllable capacitance or dielectric permittivity in magnetoelectric (ME) composites with external DC magnetic field,[1,2,3,4,5] which is known as magnetocapacitance (MC) effect, has a widely potential practical application, such as tunable spin filters, storage devices, and magnetic sensor.[4,6,7,8] As reported in previous study, multiferroic ME materials possesses ferromagnetism, ferroelectricity and ferroelasticity simultaneously,[9,10] the direct method to assess the degree of ME coupling is based on ME effect, and another widely used characterization method is an indirect measurement of dielectric response to an applied field, which is called MC method.[3]
The results show that the external magnetic field is responsible for the resonance frequency shift
The differences between Wang et al.’s theoretical results and experiment data range from 12.82% to 29.77%, which can be attributed to the linear constitutive relation of magnetostrictive material in their model for PZT-ring/Terfenol-D-strip structure, it’s urgent to establish a nonlinear model to describe the MC effect in this structure
Summary
The controllable capacitance or dielectric permittivity in magnetoelectric (ME) composites with external DC magnetic field,[1,2,3,4,5] which is known as magnetocapacitance (MC) effect, has a widely potential practical application, such as tunable spin filters, storage devices, and magnetic sensor.[4,6,7,8] As reported in previous study, multiferroic ME materials possesses ferromagnetism, ferroelectricity and ferroelasticity simultaneously,[9,10] the direct method to assess the degree of ME coupling is based on ME effect, and another widely used characterization method is an indirect measurement of dielectric response to an applied field, which is called MC method.[3]. Israel et al detected largest resonant frequency shift in multilayer capacitors, and developed a model for effective permittivity of piezoelectric layer.[21] Later on, Yao et al proposed a model to investigate the influence of temperature on the dielectric permittivity of Terfenol-D/PZT ME composites with considering the mechanical energy loss.[26] In addition, Wang et al carried out a series of experiments to improve resonance shift, and built a linear constitutive model to describe the MC effect in composite structures.[5,24,25,27,28,29] those models can describe the behavior qualitatively, the magnetostrictive materials possess a strong nonlinearity, and the resonant frequencies of magnetostrictive materials will be changed under the action of external magnetic field and pre-stress.[2,30] The differences between Wang et al.’s theoretical results and experiment data range from 12.82% (in high resonance frequency) to 29.77% (in low resonance frequency), which can be attributed to the linear constitutive relation of magnetostrictive material in their model for PZT-ring/Terfenol-D-strip structure, it’s urgent to establish a nonlinear model to describe the MC effect in this structure.
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