Naval Device Applications of Relaxor Piezoelectric Single Crystals

"This proposal is for the development of a high sensitivity pressure gradient acoustic motion sensor (accelerometer) of the flexural plate type using piezoelectric single crystals. The pressure gradient acoustic motion sensor is based on flexural plateelements operating below resonance in the accelerometer mode. The high piezoelectric coefficients for single crystals is ideal for increasing the sensitivity and low frequency range of the proposed sensor. A three axis device with combined pressure sensor(hydrophone) is proposed to realize a "Vector Sensor" suitable to meet all performance goals of the Low Frequency Bow Array (LFBA) program. Variants of the proposed sensor are also applicable to conformal arrays, hull arrays, and seismic monitoring.Improved pressure gradient sensors of the fixed diffraction type are also demonstrated. The inherent problem for pressure gradient sensors with conventional materials is the lack of sensitivity at low frequencies. This application of single crystals (SCr) seems to be ideal in the sense that the material's beneficial properties are clearlyexploited and its disadvantages are avoided. Thus, high coupling coefficient keff is exploited and the small sound velocity makes it possible to effectively use the trilaminar plate design with passive materials having a small Young's modulus for strainenhancement. The improved sensor may be used in a Low Frequency Bow Array (LFBA). Other applications in