High-Performance Shear Mode Ultrasonic Transducer Operating at Ultrahigh Temperature Fabricated with Bi₁₂SiO₂₀ Piezoelectric Crystal

Shear mode ultrasonic waves are in high demand for structural health monitoring (SHM) applications owing to their nondispersive characteristics, singular mode, and minimal energy loss, especially in harsh environments. However, the generation and detection of a pure shear wave using conventional piezoelectric materials present substantial challenges because of their complex piezoelectric response, involving multiple modes. Herein, we introduce a high-quality piezoelectric crystal Bi₁₂SiO₂₀ (BSO), exhibiting a robust piezoelectric response (<i>d</i>₁₄ = 45.1 pC/N) and a pure vibration mode. Thereafter, we developed a BSO-based shear mode ultrasonic transducer and conducted finite element simulations and experiments. Results indicated that the proposed transducer excels in exciting and receiving pure shear waves with a high signal-to-noise ratio across a wide operating frequency range. Remarkably, the proposed transducer demonstrates efficacy ranging from 25 to 800 °C, which exhibits an exceptionally high operating temperature. These excellent attributes, coupled with cost-effectiveness, render this crystal highly promising for practical SHM applications.