Magnetoelectric laminate composites of piezoelectric-magnetostrictive materials were investigated. The composites were prepared by stacking and bonding Pb(Zr, Ti)O₃ (PZT) and Terfenol-D disks. Experimental results indicated that the magnetoelectric voltage coefficient, dE/dH, increased with decreasing thickness and increasing piezoelectric voltage constant (g ₃₁) of the PZT layer. We obtained the highest magnetoelectric voltage coefficient of 4.68 V/cm·Oe at room temperature for the sample with high g₃₃ PZT of 0.5 mm in thickness. This value is about 36 times higher than the best reported value.

In this study, we investigated the capability of harvesting the electrical energy from mechanical vibrations in a dynamic environment through a “cymbal” piezoelectric transducer. Targeted mechanical vibrations lie in the range of 50–150 Hz with force amplitude in the order of 1 kN (automobile engine vibration level). It was found that under such severe stress conditions the metal–ceramic composite transducer “cymbal” is a promising structure. The metal cap enhances the endurance of the ceramic to sustain high loads along with stress amplification. In this preliminary study, the experiments were performed at the frequency of 100 Hz on a cymbal with 29 mm diameter and 1 mm thickness under a force of 7.8 N. At this frequency and force level, 39 mW power was generated from a cymbal measured across a 400 kΩ resistor. A DC–DC converter was designed which allowed the transfer of 30 mW power to a low impedance load of 5 kΩ with a 2% duty cycle and at a switching frequency of 1 kHz.

Losses in piezoelectrics are considered in general to have three different mechanisms: dielectric, mechanical, and piezoelectric losses. This paper deals with the phenomenology of losses first, then how to measure these losses separately in experiments. We found that heat generation at off-resonance is caused mainly by dielectric loss tan /spl delta/' (i.e., P-E hysteresis loss), not by mechanical loss, and that a significant decrease in mechanical Q/sub m/ with an increase of vibration level was observed in resonant piezoelectric ceramic devices, which is due to an increase in the extensive dielectric loss, not in the extensive mechanical loss. We propose the usage of the antiresonance mode rather than the conventional resonance mode, particularly for high power applications because the mechanical quality factor Q/sub B/ at an antiresonance frequency is larger than Q/sub A/ at a resonance frequency.