High strain lead-free piezo ceramics for sensor and actuator applications: A review

High strain piezoceramics are required for various sensor and actuator applications such as opening and closing of valves in fuel injector systems, for controlled flow of fuel in automobiles, applications for micro-propulsion in satellites, and other engineering applications. The precision control of fuel flow in automobiles is necessary for fuel efficiency and pollution control. In this article, lead free piezo systems having higher strain are reviewed with a focus on origin/mechanisms of high strain behavior with critical comments and future directions. Lead zirconate titanate (PZT) delivers linear but low strain of ∼0.15% of total length due to the piezoelectric effect. However, lead free piezoceramic material systems such as bismuth sodium titanate (BNT), potassium sodium niobate (KNN), barium zirconate titanate (BZT) etc. deliver high but non-linear strains, as high as 0.79% due to electrostriction.