JIA Hongrui (1990-), male, Ph.D., Lecturer. E-mail: hrjia@imut.edu.cn
Piezoelectric actuators, which are recognized as highly promising micro-displacement driving devices due to their merits of small size, large driving force, high-precision displacement, and fast response, are widely applied in fields such as microelectronics, precision machining, precision measurement, optical fiber calibration, aerospace and biomedical engineering. Relaxor ferroelectric ceramics with their outstanding electrostrain properties emerge as ideal materials for fabricating piezoelectric actuators. As a core component of piezoelectric actuators, the electric field-induced strain properties of relaxor ferroelectric ceramics have a significant influence on the stroke, precision and efficiency of the actuators, directly determining their overall performance. This review represents the research progress on the electrostrain characteristics of relaxor ferroelectric ceramics. This review focuses on the origins of electrostrain in relaxor ferroelectric ceramics, encompassing the electrostrictive effect, inverse piezoelectric effect, domain wall motion, field-induced phase transition, and defect engineering. The causes and calculation of strain hysteresis are also represented. Subsequently, this review describes the research progress on the electrostrain properties of both lead-based and lead-free relaxor ferroelectric ceramics. For lead-based ferroelectric ceramics, the focus is on three representative systems, i.e., PMN-PT, PZ-PT, and BS-PT, while lead-free ferroelectric ceramics primarily center on BNT-based, KNN-based, and BF-BT-based ceramics. In particular, this review emphasizes the recently discovered method of electric field-induced bending deformation in KNN-based ferroelectric ceramics, which is proven to significantly enhance the strain response of relaxor ferroelectric ceramics. Finally, the review analyzes the existing challenges and future prospects for the electrostrain properties of both lead-based and lead-free relaxor ferroelectric ceramics.
Lead-based relaxor ferroelectric ceramics exhibit relatively low strain hysteresis (mostly below 20%) and superior strain temperature stability, demonstrating significant advantages in electrostrain properties, which are highly favorable for applications in high-precision piezoelectric actuators. The existing lead-based relaxor ferroelectric ceramics still dominate the high-end piezoelectric actuator market. However, lead is extremely harmful to human health and the environment, and numerous domestic and international policies have explicitly restricted the usage of lead. Consequently, reducing the lead content or even achieving lead-free compositions in ferroelectric ceramics becomes an inevitable trend. Although lead-free relaxor ferroelectric ceramics, which avoid the environmental toxicity of lead, become a research hotspot in the piezoelectric materials field, their comprehensive electrostrain properties still cannot compete with those of lead-based ferroelectric ceramics for piezoelectric actuator applications. Lead-free relaxor ferroelectric ceramics can achieve high electrostrain responses through reversible phase transitions between relaxor and ferroelectric phase, they suffer from excessively large strain hysteresis and poor strain temperature stability. How to realize a balanced electrostrain properties remains a core challenge for lead-free relaxor ferroelectric ceramics. Despite these challenges, lead-free relaxor ferroelectric ceramics are expected to replace lead-based ferroelectric ceramics in mid-to-low-end applications through component design, process optimization, and reliability improvements. Nevertheless, in high precision or extreme environment scenarios, lead-free relaxor ferroelectric ceramics still struggle to fully substitute lead-based ceramics, necessitating long-term technological breakthroughs.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |