Calibration at High Pressure of Piezoelectric Elements for Deep-Submergence Hydrophones

The acoustic-pressure sensitivities of several types of piezoelectric ceramic and crystal materials have been measured at hydrostatic pressure as high as 16 000 psig. Both disks and hollow piezoelectric ceramic spheres were included in the measurement program, but pressures applied to the spheres were limited to 8000 and 12 000 psig, depending on wall thickness. All measurements were made at room temperature—about 25°C. For many of the ceramic materials, significant differences were noted between the measured sensitivities and the theoretical sensitivities as determined from data supplied by the manufacturers.