Relaxor-PbTiO³ single crystals for various applications

Abstract

Piezoelectric materials lie at the heart of electromechanical devices. Applications include actuators, ultrasonic imaging, high intensity focused ultrasound, underwater ultrasound, nondestructive evaluation transducer, pressure sensors, and accelerometers, to name a few. In this work, the advantages and disadvantages of relaxor-PbTiO3-based single crystals are discussed, based on the requirements (figure of merit) of various applications, with emphasis on recent developments of the shear properties of single crystals as a function of temperature and applied fields.

Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review

“…Table VI summarizes the thickness shear properties for various crystals with different domain configurations and compares them to commercial PZT5 and PZT8 polycrystalline ceramics [374,375]. It is evident that high shear piezoelectric coefficients and elastic compliances can be easily achieved in crystals with single domain states, such as “1R” and “1O” [162,278,292], which will benefit the broad bandwidth transducer applications (high electromechanical coupling) at low operational frequency range (large elastic compliance).…”

“…It is evident that high shear piezoelectric coefficients and elastic compliances can be easily achieved in crystals with single domain states, such as “1R” and “1O” [162,278,292], which will benefit the broad bandwidth transducer applications (high electromechanical coupling) at low operational frequency range (large elastic compliance). In addition, the high shear elastic compliance (low frequency constant) of single crystals results in small parts for the same frequency compared to polycrystalline ceramics, allowing miniaturization of the transducers or sensors [374]. …”

“…Though thickness shear exhibits ultrahigh piezoelectric coefficients, coupling factors and elastic compliances, the low field stability inherently associated with the 90° polarization rotation angle (the working direction is normal to the poling direction) will restrict their applications at high drive field condition (will be discussed in section 3.3.3.2) [141,374]. Recently, it was reported that [011] poled rhombohedral crystals possessed high face shear properties when the sample was rotated along poling direction of about 45°.…”

“…In addition, due to the uniqueness of the face shear vibration in combination with high coupling and high mechanical Q 36 , face shear crystals have been studied for tactile sensing and ultrasound motor applications [378–382]. In contrast to conventional thickness shear d 15 , the face shear vibration mode can be repolarized; i.e., the poling electrode is the same as the active electrode [141,340,374]. The ac driving field level and mechanical quality factor Q 36 of the face shear mode were reported to be significantly higher compared to thickness shear vibration modes, owing to the fact that the applied electric field in face shear vibration is along polarization direction [141,374].…”

Achieving single domain relaxor-PT crystals by high temperature poling

“…2,13,14 From the application viewpoint, on the other hand, single domain crystals exhibit many advantages, such as high thickness shear piezoelectric and pyroelectric properties. [15][16][17][18][19][20][21] As given in Table 1 To obtain domain engineered configurations, the ferroelectric crystals are poled along specific non-polar directions, so various domains appear in the crystals. These domains can form various non-180°domain configurations, satisfying the mechanical compatibility to minimize the strain energy.…”