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. 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 d33 (the induced charge per unit force applied in the same direction) of above 300 picocoulombs per newton (pC N(-1)), and texturing the material leads to a peak d33 of 416 pC N(-1). The textured material also exhibits temperature-independent field-induced strain characteristics.

O 3 polycrystals exhibit piezoelectric properties comparable to those of lead zirconium titanate ceramics which are high-performance piezoelectric materials. The properties of the Pb-free piezoelectric ceramic are due to the existence of a morphotropic phase boundary in the alkaline niobate-based perovskite solid solution. It is expected that the new material is a leading candidate for environmentally friendly piezoelectric devices. -(SAITO, Y.; TAKAO, H.; TANI, T.; NONOYAMA, T.; TAKATORI, K.; HOMMA, T.; NAGAYA, T.; NAKAMURA, M.; Nature (London, UK) 432 (2004) 7013, 84-87; Toyota Cent. Res. Dev. Lab., Nagakute, Aichi 480-11, Japan; Eng.) -W. Pewestorf 03-016

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