Fabrication and modeling of bismuth titanate-PZT ceramic transducers for high temperature applications

Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi₄Ti₃O₁₂) composites has a competitive advantage to standard ultrasonic transducers is conforms to non-Euclidean geometries and operates at high temperature (Curie-Weiss temperature 685 °C) and is mechanically coupled to the substrate. However, an issue with many high temperature transducers such as bismuth-titanate ceramics is that they have relatively low d₃₃ (about 12-14 pC/F in Bi₄Ti₃O₁₂ versus 650 pC/F in PZT-5H). It is common conception that high-temperature capability comes at the cost of electromechanical coupling. It will be shown that the high temperature capability of bismuth-titanate-PZT composite transducers using the spray-on deposition technique previously developed, improves the electro-mechanical coupling while maintaining the high temperature performance and mechanical coupling. This material could provide advantages in harsh environments where high signal to noise ratios are needed.