Lead-free piezoceramics

Lead has recently been expelled from many commercial applications and materials ( for example, from solder, glass and pottery glaze) owing to concerns regarding its toxicity. Lead zirconium titanate (PZT) ceramics are high-performance piezoelectric materials, which are widely used in sensors, actuators and other electronic devices; they contain more than 60 weight per cent lead. Although there has been a concerted effort to develop lead-free piezoelectric ceramics, no effective alternative to PZT has yet been found(1-14). Here we report a lead-free piezoelectric ceramic with an electric-field-induced strain comparable to typical actuator-grade PZT. We achieved this through the combination of the discovery of a morphotropic phase boundary in an alkaline niobate-based perovskite solid solution, and the development of a processing route leading to highly [001] textured polycrystals. The ceramic exhibits a piezoelectric constant d(33) ( the induced charge per unit force applied in the same direction) of above 300 picocoulombs per newton (pCN(-1)), and texturing the material leads to a peak d(33) of 416 pCN(-1). The textured material also exhibits temperature-independent field-induced strain characteristics.