Fabrication of BiScO3-PbTiO3/epoxy 1-3 piezoelectric composites for high-temperature transducer applications

1-3 piezoelectric composites are widely used in piezoelectric ultrasonic transducers due to their high thickness electromechanical coupling factor. However, the applications of the composites in high-temperature fields are limited by the low heat resistance of both the piezoelectric and polymer phases. To tackle this, we designed and fabricated the BiScO3-PbTiO3/epoxy high-temperature 1-3 piezoelectric composites. These composites exhibit a high thickness electromechanical coupling factor k(t) of 63%, a large piezoelectric coefficient d(33) of 470 pC/N, and a pure thickness vibration mode. Furthermore, we fabricated a high-temperature transducer based on the BiScO3-PbTiO3/epoxy 1-3 composites. The bandwidths of the composites measured in water and silicone oil (30% and 23%, respectively) are approximately 1.65 times greater than those of monolithic piezoelectric ceramics (18% and 14%, respectively). The bandwidth of the transducer can be increased to 78% by adding a porous alumina backing layer, with the working temperature reaching up to 300 degrees C. The results indicate that the BS-PT/epoxy 1-3 composite is a potential candidate for high-temperature transducer applications.