Biased lead zirconate titanate as a high-power transduction material

High-power, underwater transducers utilizing polarized piezoelectric ceramic material are usually limited in drive amplitude so that depolarization does not occur, but application of a dc bias field in the polarization direction allows the use of higher ac drive fields. To demonstrate the feasibility of biased operation as a means of achieving higher power, a thin-walled, spherical-shell transducer was constructed of Channel 5800 and tested in NUWC's Acoustic Pressure Tank Facility at a hydrostatic pressure of 1400 psig (9.65 MPa). The transducer was successfully driven to 33 V/mil (1.3 MV/m) rms with an accompanying bias field of 31 V/mil (1.2 MV/m). The source level was 206 dB re: 1 mu Pa.m at 61 kHz, corresponding to a 10-dB improvement over the unbiased drive limit of 10 V/mil (0.4 MV/m) rms and 196 dB re: 1 mu Pa.m. (C) 1999 Acoustical Society of America. [S0001-4966(99)04204-6].