Single crystal piezoelectric composites for advanced NDT ultrasound

Design factors of intravascular dual frequency transducers for super-harmonic contrast imaging and acoustic angiography

“…In addition, the piezoelectric 1-3 composite was designed with little lateral resonance at the working frequency. The lowest lateral resonant frequency f L in the 1-3 composite material is (Jiang et al , 2006;Jiang et al , 2007b;Jiang et al , 2007a)…”

Relaxor-PT Single Crystal Piezoelectric Sensors

“…First, the problem of the low fracture toughness has been handled by using optimized fabrication processes. Current fabrication of relaxor-PT crystal sensors usually involves the optimal dicing speed, dicing depth, blade type, and lapping speed for the precise sensor shaping without cracks and chips [121,122]. Second, the low temperature limit and the low coercive field of the first generation relaxor crystals have been improved.…”

“…(a) Although the growth method for large crystals have been demonstrated [25], relaxor-PT single crystals still cost more than the lead-based piezo-ceramics; (b) Relaxor-PT crystals are vulnerable to chipping and cracking during the shaping process of the sensor fabrication due to their low fracture toughness and possibly high internal stresses [121,122]; (c) Low Curie temperature, phase transition temperature, and coercive field of the first generation relaxor single crystals are not favorable for piezoelectric sensors; (d) High thermal sensitivity of the relaxor crystals requires a proper compensation for the accurate sensing of purposed mechanical stimulus.…”

Relaxor-PbTiO3 single crystals for various applications

“…Furthermore, the composites are found to possess the advantage of lower acoustic impedance, being about 12 to 20 MRayls, much smaller than single crystals (~30 MRayls), which will benefit the matching of the transducers to the human body (~3 to 5 MRayls) [41]. However, recent experimental data for PMNT crystal/epoxy 1–3 composites (piezoelectric composite- micromachined ultrasound transducer PC-MUT) operating at high frequencies > 20 MHz exhibited a large decrease in electromechanical coupling, with values being less than 0.80 [42], [43], showing a strong scaling effect and leading to the question of the origin of property degradation at high frequencies [44], [45]. Besides medical imaging transducers, other applications, including underwater acoustic transducers, nondestructive evaluation (NDE) transducers, piezoelectric actuators, and sensors are also benefit from the high extensional piezoelectric properties of relaxor-PT crystals [1].…”

“…In addition, the reported coupling factors for PMNT/epoxy 1–3 composites were included in Fig. 5 [42], [43]. Note that the corresponding resonance frequencies on the top x-axis of Fig.…”