Porous Piezoelectric Ceramic Transducer

Abstract

Porous piezoelectric ceramics of Pb(Zr, Ti)O3, (P-PZT), have been newly developed to apply to transducers in an echo sounder. The P-PZT was prepared from a mixture of PZT and poly-methyl-methacrylate (PMMA) powders. The piezoelectric characteristics of the P-PZT such as the dielectric constant (ε), voltage output constant (g constant), acoustic impedance (Z c) and Q were evaluated. The P-PZT was employed in an echo sounder of 200 kHz, and its transmitting and receiving properties were measured in water. In these measurements, the P-PZT showed suitable characteristics for the echo sounder, which required high sensitivity, wide frequency bandwidth and high resolution. High sensitivity was realized by the large g constant and low Z c of P-PZT which made the impedance matching with water much easier. In the acoustic response to the burst wave, the rise and fall time were shortened to 1/3 that of the conventional PZT transducer.

Porous piezoelectric ceramic hydrophone

“…Therefore in the last decades new materials with improved piezoelectric properties and good qualities for hydroa͒ Electronic mail: floriana@idac.rm.cnr.it phone applications, obtained by introducing soft material inhomogeneities ͑e.g., voids͒ into piezoelectric ceramics and polymers, have been investigated and tested in hydrophones. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In porous piezoelectric materials, a partial decoupling between transversal and longitudinal effects avoids canceling, therefore d h increases. Moreover, due to the lower dielectric constant, g h is furthermore increased.…”

Uniqueness theorem, theorem of reciprocity, and eigenvalue problems in linear theory of porous piezoelectricity

“…Porous piezoelectric materials (PPMs) are of interest for applications such as low-frequency hydrophones, underwater sensing, and actuation applications [21][22][23] . This is due to the high hydrostatic figures of merit and low sound velocity of these materials which leads to the reduction of acoustic impedance and the enhancement of the coupling with water.…”

Piezoelectric effect on the velocities of waves in an anisotropic piezo-poroelastic medium

“…The resulting piezoelectric porous materials are widely used for applications such as low-frequency, miniature hydrophones, accelerometers, vibratory sensors and contact microphones (Arai et al 1991; *mohan_here@rediffmail.com Hayashi et al 1991). Due to lower acoustic impedance, these materials can be used to improve mismatch of acoustic impedance at the interfaces of medical ultrasonic imaging devices or underwater sonar detectors (Mizumura et al 1991).…”