Giant electric field–induced strain in lead-free piezoceramics

Abstract

Piezoelectric actuators are indispensable over a wide range of industries for their fast response and precise displacement. Most commercial piezoelectric actuators contain lead, posing environmental challenges. We show that a giant strain (1.05%) and a large-signal piezoelectric strain coefficient (2100 picometer/volt) are achieved in strontium (Sr)–doped (K,Na)NbO 3 lead-free piezoceramics, being synthesized by the conventional solid-state reaction method without any post treatment. The underlying mechanism responsible for the ultrahigh electrostrain is the interaction between defect dipoles and domain switching. The fatigue resistance, thermal stability, and strain value (0.25%) at 20 kilovolt/centimeter are comparable with or better than those of commercial Pb(Zr,Ti)O 3 -based ceramics, showing great potential for practical applications. This material may provide a lead-free alternative with a simple composition for piezoelectric actuators and a paradigm for the design of high-performance piezoelectrics.

Achieving giant electrostrain of above 1% in (Bi,Na)TiO 3 -based lead-free piezoelectrics via introducing oxygen-defect composition

“…The mesoscopic structural modifications such as designing core-shell structures or tailoring the domain structures by periodic orthogonal poling can boost the electrostrain via enhancing reversible non-180° domain switching ( 16 , 20 ). Of particular interest is that the BiFeO 3 -PbTiO 3 -LaFeO 3 (BF-PT-LF) lead-based system achieved a record value of 1.3% by synergistically improving the intrinsic and extrinsic contributions to electrostrain ( 15 ), which is a representative perovskite-based ceramic systems with a strain greater than 1% ( 21 , 22 ).…”

“…Materials that produce a strain in response to an applied electric field are critical for actuator usage (4,5). Considerable research efforts on perovskite ferroelectrics over the past decades have led to the discovery of many materials with excellent electrostrain properties (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Among these materials, lead-free Bi 0.5 Na 0.5 TiO 3 (BNT)-based ceramics have relatively large electric field-induced strains but with reported electrostrains being lower than 0.5% (4).…”

“…It is generally believed that the electrostrain in ferroelectrics is attributed to intrinsic piezoelectric effect (8,9), polarization rotation (10), field-induced phase transitions (11)(12)(13)(14)(15), domain switching (16)(17)(18)(19)(20), defect regulation (21,22), etc. Several approaches have been developed to achieve high electrostrains.…”

“…Recently, material design based on defect chemistry of ferroelectric oxides has emerged as an effective strategy for engineering functional properties ( 22 , 25 ). For example, electric field–induced rearrangement of oxygen vacancies resulted in extraordinarily high piezoelectricity in Gd-doped CeO 2 - x thin films ( 26 ).…”

High piezoelectricity and low strain hysteresis in PMN–PT-based piezoelectric ceramics

“…Most ceramics or crystals possess large H in strain-electric field curves. Although a large strain (~over 0.2%) can be achieved, there is > 25% strain hysteresis in Bi0.5Na0.5TiO3 based ceramics [18][19][20], and also >15% in K0.5Na0.5NbO3 based ceramics [21][22][23], which restricting their applications in precisely controlled devices and system [24,25]. Compared with the lead-free ceramics, lead-based ceramics has a much smaller strain hysteresis.…”