And Lead is of course toxic, which makes it more or less not biocompatible and therefore not unuseable in biomedical applications for implantation in the body. Furthermore, with new Lead regulations in places like Europe, it’s basically very difficult or illegal to introduce products which contain lead, this was one of the big pushes a few years ago to put research funding into leadless solders for electronic products. So it was cool to read from New Scientist that researchers from the University of California, Berkeley including Robert Zeches and Ramamoorthy Ramesh have developed a piezoelectric-like material based on bismuth ferrite, which reatins properties similar to PZT, but without using any Lead. This could be a significant step for smart materials.

The bismuth ferrite material reacts to electrical fields and exhibits a strain of 1.5% when electrically driven.  A strain of 1.5% might seen small for most structural smart materials applications. However, from previous research dealing with active fiber composites composed of PZT fibers and interdigitated electrodes, actuation strains on the order of 0.16% have been seen when driving the actuator at 4000 Volts. This AFC technology has been used to develop active rotor blades and active wing technology, so an actuation strain of 1.5% with a green smart material really isn’t that bad.

At the moment the bismuth ferrite exists as a thin film technology, but if developments are made in the manufacturing process to produce wafers or fibers, it could find many applications in aerospace and automotive applications on the industrial scale.  For example, in active damping systems in cars, an application where it would be difficult to use Lead-based materials due to envirnomental regulations (Lead-free countries). And of course, those would need to be cost-effective manufacturing processes.