High power density NaNbO₃-LiTaO₃lead-free piezoelectric transformer in radial vibration modes

Abstract

In the present work, the sintering temperature was able to substantially influence the microstructure and electrical properties of the lead-free ceramic 0.88NaNbO 3 -0.12LiTaO 3. This composition without any acceptor doping presents a high mechanical quality factor, Q m , value of 1469 and a high Curie temperature of 305 °C by optimizing the sintering temperature at 1330 °C. We applied this material to make a device of disk-shaped piezoelectric transformers with a ring-dot structure and further focused on investigating the characteristics of the piezoelectric transformers. With matching load, a maximum efficiency of 92% occurs in the fundamental mode, and the maximum voltage gains are 5.5 and 3.7 for the fundamental and third radial vibration modes, respectively. The experimental results show a maximum output power of 10.5 W with a temperature rise of 27 °C. It is noteworthy that a high output power density (as high as 32.8 W cm −3 ) was obtained under a maximum input voltage of 180 V, which is comparable to the performance of PZT in a piezoelectric ceramic transformer device.

Experimental validation of axially polarized multilayer piezoelectric composite cylindrical transducers with adjustable multifrequency

“…It is noticed that the multiple electrodes layout have been successfully applied in piezoelectric ring/disk transformers (Guo et al, 2007a, 2007b; Ho, 2007; Sun et al, 2015). These electrodes are usually isolated by the annular gaps.…”

Piezoelectric PZT thin-film transformers with a ring–dot structure

“…[9][10][11][12] Among the available architectures of devices for stepdown applications, the ring-dot type transformer, by which notable conversion characteristics have been realized, is deemed to be promising. [1][2][3][4][13][14][15] In this structure, an electrode for a common ground is located on one side of a piezoelectric ceramic disk which is poled along the thickness direction. On the other side of the disk, there exist input and output electrodes separated by a small gap.…”

Vertically aligned carbon nanotube arrays as thermal interface material for vibrational structure of piezoelectric transformer

“…As a typical vibrational device, piezoelectric transformers (PTs) can adjust the voltage through vibration propagation generated from the direct/converse effects of piezoelectric structures. PTs possess advantages of high power density, electromagnetic immunity and good electrical isolation compared with traditional electromagnetic transformers [9][10][11][12]. In theory, a power density as high as 300 W cm −3 can be obtained [13].…”