The Effects Of Piezoelectric Material Properties On Piezoelectric Transformer

The piezoelectric materials such as PZT ceramics have been used to design devices many years in the field of medical, military, industrial, civilian, and so on. For example, piezoelectric transformer, piezoelectric filters, ultrasonic transducer, etc. But with the development of the relaxor ferroelectric crystal growth, the scholars already succeeded grasp the preparation method of outstanding ferroelectric crystal. At present, numerous empirical data demonstration show the piezoelectric coefficient and electromechanical coupling coefficient of PMN-PT single crystal are much greater than those of ordinary PZT ceramics. This fine nature has aroused the general scholar's great interest recently. The superior properties also make it a promising candidate for high performance ultrasonic devices.In view of the principle of piezoelectric transformer is make use of direct and converse piezoelectric effects, via transfer electric to mechanical energy, then transfer mechanical to electric energy. In short, the core of piezoelectric transformer is the piezoelectric material, the performance of piezoelectric transformer concerns the material property. This article studied the properties difference of the soft ceramic PZT-5H, the hard ceramics PZT-4, PZT-8 and the single crystal PMN-29%PT, and we explained it from the angle of different ions doped lead to ferroelectric domains change.We also made the piezoelectric transfoemer using the PZT-5H, PZT-4, PZT-8 ceramics and PMN-29%PT single crystal. The theoretical modeling explain the experimental results. The results displayed the difference of the materials. The experiment results also show the electromechanical couping factor plays the leading role in small signal. PMN-29%PT single crystal was best, especially the power density of PMN-29%PT single crystal was largest on the matching load, which was much larger than PZT ceramics.Until now, little research about radial vibration mode of PMN-PT single crystal has been reported, so we chose the radial vibration mode. Our experiments demonstrated that the radial vibration mode of PMN-29%PT was also excellent. There is nearly no spurious vibration mode around the resonance frequence,the planar electromechanical couping factor is as high as 84%. All of these demonstrate the radial vibration mode of PMN-PT single crystal would be favorable for practical applications.