The Naval Undersea Warfare Center Division Newport has developed, tested, and patented piezoelectric transducers that deliver high strain over a large bandwidth while requiring a low drive level. The key is the application of small levels of compressive stress to domain engineered PIN-PNM-PT single crystals. The pre-stress brings the crystal near the phase transition point between rhombohedral (Fr) and orthorhombic (Fo) states so that a small AC electrical field can induce a transition from Fr to Fo and generate the strain that drives the transducer. A DC bias electrical field is also employed to lower the stress level at which the transition occurs, resulting in a system where a small variation in either stress or electric field can trigger the transition.
The technology is amenable to a variety of transducer designs, including the simple, robust, and tunable design shown in the graphic to the right. The sharp reversible domain switching effect of the Navy’s technology leads to potential applications in a broad field, including sound projectors, ultralarge stroke and nonlinear actuators, piezoelectric transformers, pulsed field sources, magnetoelectric micropumps, energy harvesting, and composite magnetoelectric magnetic sensing.
- High Strain: Delivers ~0.5% strain levels, more than 100x greater than PZT 8, the Navy standard piezoelectric projector material, and a 10x increase compared to unstressed crystals of the same composition
- Low Drive: Less than ~0.1 MV/m required to trigger phase transition, a 4x reduction compared to unstressed crystals of the same composition
- High Performance: Up to a 46 dB increase in acoustic energy density compared to PZT 8
- Compact: High strain enables device size reduction of up to 100x while maintaining a given output performance compared to other devices
- US Patent 8,604,676
- Potential for collaboration with Naval Undersea Warfare Center Division Newport researchers