Giant electric field–induced strain in lead-free piezoceramics

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)NbO3 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)O3-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. Description Get the lead out Piezoelectric materials convert an electrical signal into mechanical strain, making them vital as actuators and sensors. However, the best materials currently in use contain lead. Huangfu et al. found that doping a potassium–sodium niobium oxide with strontium improved the piezoelectric properties. This material had a high strain response at electric fields similar to its leaded counterparts and could potentially be a replacement for some lead-based piezoelectrics. —BG Strontium doping improves the performance of a lead-free piezoelectric material.