High-temperature piezoelectric crystals ReCa₄O(BO₃)₃: a review

Abstract

High-temperature sensors are desirable for structural health monitoring and/or nondestructive evaluation of next-generation turbines, more efficient jet engines, and the furnace components of electrical power plants. Of all the investigated high-temperature piezoelectric materials, rare-earth calcium oxyborate crystals ReCa4O(BO3)3 (ReCOB, Re: rare-earth) exhibit attractive advantages for high-temperature piezoelectric sensing. In this paper, the electroelastic properties of different ReCOB piezoelectric crystals are investigated. The crosstalk between various vibration modes are discussed, from which the optimized crystal cuts are achieved. Furthermore, temperature dependences of the electrical resistivity, dielectric, elastic, piezoelectric, and electromechanical properties of ReCOB crystals are studied. Finally, the thermal properties, including thermal expansion, specific heat, and thermal conductivity at elevated temperatures are studied and compared with commercially available high-temperature piezoelectric crystals.

Crystal growth and characterization of thulium calcium oxyborate high-temperature piezoelectric crystals

“…Among the investigated electromechanical coupling factors, the transverse coupling k 12 , which was determined to be on the order of 15.4% at RT, exhibited the highest temperature stability, leading to a minimal variation of 5.4% over the test temperature range, close to that of YCOB (variation of k 12 being 4.5%). 36 However, the transverse coupling k 13 and shear coupling k 26 and k 35 exhibited different temperature-dependent behaviors with relatively large variations on the order of −10.9%, −16.7% and 21.8%, respectively.…”

Crystal Structure of Gd(Ca3.319Sr0.681)O[BO3]3 and Gd(Ca2.592Sr1.408)O[BO3]3

“…The family of the rare earth calcium oxoborates $$RX_2 Z_2$$O[BO 3 ] 3 (RCOB, space group $$C1m1$$) contains promising candidates to overcome this limit. [ 2 ] RCOB was discovered in 1974 by Kindermann [ 3 ] and was first described by Khamaganova et al. [ 4 ] as a non‐centrosymmetric monoclinic material.…”

A Digital-Twin Framework for Predicting the Remaining Useful Life of Piezoelectric Vibration Sensors with Sensitivity Degradation Modeling

“…Therefore, only when the vibration of an aeroengine is measured in real-time can the safety of an aircraft be maintained to the greatest extent [3]. The exploitation of piezoelectric vibration sensors (PVSs) provides one approach to this challenge, due to the stability of their long-term operation under high-temperature conditions [4]. As an example, the CFM56 turbofan engine in the Boeing 737 uses PVSs to identify working states in every individual rotational cycle [5].…”