High performance piezoelectric crystal cut designed using LiNbO3 for high temperature acoustic emission sensing application

Lithium niobate (LiNbO3, LN) is a kind of multifunctional crystal material. In this study, an optimum piezoelectric crystal cut (XZt/28 degrees) with a central resonance frequency of 150 kHz and stable electro-elastic performance over a wide temperature range of 20-500 degrees C was explored. Furthermore, a piezoelectric acoustic emission sensor was designed and fabricated using the optimum crystal cut, followed by Hsu-Nielsen tests for potential high-temperature structural health monitoring (SHM). The fabricated acoustic emission sensor was found to show a high response for detecting the Lamb wave both at room temperature and a high temperature of 500 degrees C, and the peak-to-peak values were obtained to be as high as 69.8 mV and 41.3 mV, respectively. Significantly, the signal-to-noise ratio (SNR) value of the sensor was evaluated to be >20 dB at a high temperature of 500 degrees C. The above results support that the LN-based piezoelectric acoustic emission sensor is promising for high-temperature structural health monitoring.