Fabrication and electrical properties of ultrasonic motor for bismuth layer-structured ferroelectric ceramics (Sr_0.7Ca_0.3)₂Bi₄Ti₅O₁₈

Abstract

Recently, there are many reports of ultrasonic motors using lead-free piezoelectric ceramics with relatively high piezoelectric strain constant d₃₃. However, ultrasonic motors using bismuth layer-structured ferroelectrics (BLSFs) with small d₃₃ have not been reported yet. In this study, we attempted to demonstrate ultrasonic motors using one of the BLSF ceramics, (Sr_0.7Ca_0.3)₂Bi₄Ti₅O₁₈. As a result, rotation of the rotor is confirmed, and the rotational speed of 300 rpm at the center frequency was observed. In addition, the temperature rise under the continuous driving at room temperature was about 20%. And, the frequency variation from the center frequency was very small of about 0.02%.