•A new capacitive type magnetoimpedance effect is achieved that based on the variations of relative effective permittivity with magnetic field.•An strong capacitive type magnetoimpedance effect of more than 469% is achieved in the anti-resonance window of the transducers vibrator.•Dramatic change in the magnitude of magnetoimpedance show that its response depends on the demagnetization factor of magnetic material.•Magnetically tunable sensitivity can be improved significantly by demagnetization factor depend on size effect.A magnetically tunable magnetoelectric transducer vibrator made of ring-type Pb(Zr,Ti)O3 (PZT)/Terfenol-D (TDF) composite has been developed. We investigated the size effects of the vibrator resonance frequency. The relative effective permittivity and relative effective permeability of magnetoelectric composite are related to the size of ferromagnetic material. Improvements of about 469%, 176% and 696% of magnetoimpedance, magnetoinductance and magnetocapacitance have been achieved at anti-resonance of the vibrator, respectively. The dramatic change in the magnitude of capacitive type magnetoimpedance, magnetoinductance and magnetocapacitance shows that their responses depend on the size of the magnetostrictive ring in the transducer composite vibrator. The capacitive type magnetoimpedance effect can be substantially enhanced via properly designing the inner radius of magnetostrictive ring, which providing an alternative avenue for increasing magnetically tunable sensitivity.

•The magnetostrictive and piezoelectric phases are coupled through shear stress in strip–ring composite structure.•Size effects of magnetically tuned electromechanical resonances.•The influence of single magnetic field on resonant frequencies shift in magnetoelectric composites.In this article we present a theory describing the influence of the magnetostrictive component size on magnetically tuned electromechanical resonance frequencies (EMRs) for ferromagnetic–piezoelectric heterostructures. An analytical model to evaluate the magnetically tuned EMRs offset in strip–ring magnetoelectric composite structures is introduced. The model is applied to the specific case of PZT (ferrite-lead zirconate titanate)-strip/TDF (Terfenol-D)-ring composite. Numerical simulation of magnetically tuned EMRs offset indicated that the magnetically tuned EMRs depend significantly on the ratio of outer and inner radii of the magnetostrictive ring. A maximum value for the magnetically tuned EMRs offset Δf of −2.139 × 105 Hz is found in a magnetic field H = 8.641 × 10−2 T for b = 1.2a (b and a are outer and inner radius of magnetostrictive ring). This theoretical work is significant for designing ME devices and understanding the magnetically tuned EMRs in strip–ring composite structures.

The giant room-temperature magnetocapacitance is reported in the Terfenol-D/PZT/Terfenol-D which is composed of a trilayer structure. A giant magnetocapacitance as large as 1200% is observed at the resonant frequency of 52.17 kHz and a saturated magnetic field of 1.5 kOe. We experimentally demonstrate that such magnetocapacitance effect correlates with the frequency shift of harmonic oscillator, i.e., PZT, which resulted from the applied magnetic field. In addition, theoretical analysis shows that the frequency shift is attributed to the product effects of the magnetic field-tuned Young's modulus of the Terfenol-D and the strain-capacitance of the ferroelectrics PZT. One can apply this characteristic of resonance frequency shift to design magnetocapacitance composites with a frequency-tunable magnetic filter.