Broadband resonant acoustic emission sensor based on [001]-textured Mn-PMN-PZT piezoelectric ceramics

Textured piezoelectric ceramics are emerging as a new material for next-generation high-performance acoustic emission (AE) sensors due to their high piezoelectric constants and large electromechanical coupling coefficients. In this work, we designed and fabricated AE sensors based on conventional untextured PZT-5A ceramics and newly developed textured Mn-PMN-PZT ceramics referred to as AE_U and AE_T. Finite element method was used to examine the effect of the aspect ratio (G = l/t) on the resonant characteristics and electromechanical behavior, revealing that when G < 0.85, the textured component exhibits a pure longitudinal vibration mode and maintains a large effective electromechanical coupling coefficient (k_eff of 0.87–0.89), far exceeding that of the untextured one (k_eff = 0.67). Guided by these results, both AE_U and AE_T were fabricated with identical geometries (l = 6 mm, t = 8 mm, G = 0.75) for direct comparison. Sensitivity measurements show that AE_T achieves a peak sensitivity of 71.8 dB and a −10 dB bandwidth of 173 kHz (bandwidth range of 56–229 kHz), representing improvements of approximately 3.5 dB and 73 kHz over AE_U. In transformer partial discharge (PD) tests, AE_T generated an output voltage amplitude about 2.8 times that of AE_U without missed or false detections, demonstrating better detection capability. These findings highlight the advantages of using high-performance textured piezoelectric ceramics to replace conventional PZT in AE sensor development, and provide a promising material and device design for health monitoring of power electronic equipment.