Electromechanical Resonance Frequency Research Articles

Resonant magnetoelectric coupling in trilayers of ferromagnetic alloys and piezoelectric lead zirconate titanate: The influence of bias magnetic field

We present the first data and theory for the bias magnetic field dependence of magnetoelectric coupling in the electromechanical resonance (EMR) region for ferromagnetic-piezoelectric heterostructures. Trilayers of Permendur, a $\mathrm{Co}\ensuremath{-}\mathrm{Fe}\ensuremath{-}\mathrm{V}$ alloy, and lead zirconate titanate were studied. Measurements of the magnetoelectric (ME) voltage coefficient ${\ensuremath{\alpha}}_{E}$ indicate a strong ME coupling in the low-frequency range and a giant ME effect due to EMR at $200--300\phantom{\rule{0.3em}{0ex}}\mathrm{kHz}$ for radial modes and at $\ensuremath{\sim}2.7\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$ for thickness modes. Data were obtained for the bias field $H$ dependence of two key parameters, the EMR frequency ${f}_{r}$ and the ME coefficient ${\ensuremath{\alpha}}_{E,R}$ at resonance. With increasing $H$, an increase in ${f}_{r}$ and a rapid rise and fall in ${\ensuremath{\alpha}}_{E,R}$ are measured. In our model we consider two mechanisms for the magnetic field influence on ME interactions: (i) a shift in the EMR frequency due to changes in compliance coefficients ($\ensuremath{\Delta}E$ effect) and (ii) variation in the piezomagnetic coefficient that manifests as a change in ${\ensuremath{\alpha}}_{E,R}$. Theoretical profiles of ${\ensuremath{\alpha}}_{E}$ vs frequency and estimates of frequency shift based on the $\ensuremath{\Delta}E$ effect are in excellent agreement with the data.

Piezoelectric ultrasonic motor by co-extrusion process

A miniaturized piezoelectric ultrasonic motor (USM) composed of four rectangular piezoelectric plates (PZN-PZT) and a stator (PZN-PZT/Ag) was developed using a co-extrusion process. Two facing neighboring piezoelectric layers were poled in the outer direction of the stator, while two other layers were poled in the inward direction. The USM generated elliptical motion at its ends by combining the bending motions in the x- and y-axis of the stator when two voltage signals that were phase shifted by π/2 were applied at the electro-mechanical resonance frequency. The USM was operated at the first bending vibration mode (∼51 kHz) at 30 Vp-p. The maximum displacement of the x- and y-axis were 1.5 μm and 0.5 μm, respectively, which were high enough for use as a stator in USM applications.

Resonant amplification of the magnetoelectric effect in ferrite-piezoelectric composites

The magnetoelectric effect in ferrite-piezoelectric composites is considered. A theory of the magnetoelectric effect in the electromechanical-resonance region for disk-shaped samples is presented. The magnetooptical coefficient is calculated for longitudinal and transverse orientations of electric and magnetic fields. It is shown that the effect increases by a few orders of magnitude at the electromechanical-resonance frequency. The frequency dependence of the effect is experimentally studied for a ferrite-nickel spinel-PZT composite. A resonant increase in the effect is observed (in agreement with the theory); the highest value of the magnetoelectric coefficient was 15 V/(cm Oe).

Dielectric and Pulsed Spectroscopy of Shear Mode PZT Microactuator

ABSTRACTFerroelectric lead zirconate titanate (PZT) is the main industrial product in piezoelectric ceramic materials used for sensor and actuator applications. High precision in manufacturing of microelectromechanical systems is essential to get demanded performance accuracy. An adequate and preferably non-destructive measurement technique is desired to characterize the materials properties at various stages of device fabrication as well as to find correlation between the processing parameters, microstructure and functional properties. We report on a new pulsed technique, which has been employed to characterize all relevant properties of special machined array of PZT channels quickly, reliably and reproducibly: dielectric constant, loss factor tan σ, electromechanical coupling coefficient, resonance frequency and mechanical quality factor Q as well as temperature dependencies of these parameters.

Anomalous degradation of electromechanical coupling and resonance frequency in tonpilz transducers

In recent years, the bandwidth of sonar arrays has been increasing, requiring wide bandwidth transducer element designs. Tonpilz transducers have come to be the dominant element design in such arrays. The location of the fronting blocks flexural resonance relative to the operating band becomes a critical feature of these wideband element designs. In some cases, unexpectedly low electromechanical coupling and resonance frequencies have occurred. These results are typically attributed to “cross modes” due to ceramic stack geometry or interface compliance at the stack ends, though no conclusive evidence exists for either. In a series of modeling investigations utilizing the piezoelectric capabilities of the commercial finite element code ANSYS, mode shapes at the fundamental resonance of a number of designs were compared. In certain designs, excessive and unsuspected bending motion in the fronting block was found to degrade the electromechanical coupling and resonant frequency. The results of these investigations will be presented along with some possible solutions.

Determination of the piezoelectric constant d14 of trigonal selenium crystals

Using the gain-bandwidth method, the piezoelectric constant d 14 of trigonal selenium has been deduced from measurements of the admittance and the electromechanical resonance frequencies of appropriately cut bars. The value was found to be | d 14| = (2.54 ± 0.2) × 10 −2 C/ N.

Stress Plate Optical Modulator for Circular Dichroism Measurements

The fused silica stress plate modulator described below offers several advantages over the other known electrooptic modulation devices: primarily, high transmission over a broad wavelength range, and large aperture. When operated at its electromechanical resonance frequency of 16.7 kHz, the modulator requires only low voltage, low power drive to operate as a +/-lambda/4 plate. Complete constructional details are given, including a model from which resonance frequencies may be calculated. As part of a circular dichroism apparatus, the modulator has allowed measurement of effects as small as 1 part in 10(5). The possibility of extension of the operating range into the vacuum uv is discussed.

Temperature Dependence of Dynamic Magnetostrictive Properties in Nickel-Cobalt-Chromium Alloys

The variation of electromechanical coupling coefficient and resonant frequency with temperature, over the range −60° to +60°C, has been determined for nickel and certain alloys of nickel with cobalt and chromium. The results indicate that some of the alloys possess almost temperature-in-variant properties near room temperature. This effect is explained qualitatively in terms of the magnetocrystalline anisotropy energy and magnetostriction of the alloys.