Expanded Operating Domain Piezoelectric Single Crystals

Single crystal relaxor ferroelectrics, PMN-PT, have shown great promise for broad bandwidth sonar transducers. However, the benefits of PMN-PT are somewhat counterbalanced by its maximum temperature limitation (~80 to 95°C), low coercive field (~2kV/cm) and low mechanical quality factor (60-80) for compact, high power and high duty cycle applications. The new crystal compositions with expanded operating temperature ranges are highly desired for such applications. The Phase I results suggest that PMN-PT can stabilize the perovskite phase of the crystal melt when it consists of high temperature capable binary compounds. The resulting PMN-PT based ternary compounds have significantly increased phase transition temperature and coercive field and growth conditions very similar to pure PMN-PT. In phase II, TRS proposes to grow large-size, PMN-PT-based ternary relaxor piezoelectric crystals with optimized compositions to further expand operating temperature ranges. By applying the well-established Bridgman process, not only will the cost and time for developing these new materials be dramatically reduced, but also the manufacturability of these materials will be insured. The goal is to elevate phase transition temperature to 125oC -150 oC, coercive field to 5kV/cm and mechanical Q to over 150.