Lead-Free Piezoelectric Material Could Serve as Replacement for PZT

Since the EU enacted the Restriction of Hazardous Substances directive (RoHS) several years ago, which bans several substances in electronics that are deemed hazardous, lead has become a material non grata. And though lead-based piezoelectric materials are currently exempt from the ban, some experts speculate that the materials may soon suffer a similar fate. To address this issue, materials engineers at the University of Leeds (UK) have developed a lead-free ceramic that could replace lead zirconium titanate (PZT) in many applications.

Piezoelectric materials such as PZT have lent their favorable attributes to a variety of medical applications, especially ultrasound transducers. In this capacity, PZT generates sound waves, transmits the echoes to a computer, and converts the information into a picture. The lightweight, lead-free ceramic developed by the Leeds researchers could offer a lead-free alternative without compromising performance, according to the researchers.

The researchers employed high-intensity synchroton radiation to demonstrate an electric-field-induced phase transformation in their ceramic. "We were able to probe the interior of the lead-free ceramic potassium sodium bismuth titanate (KNBT) to learn more about its piezoelectric properties," says Tim Comyn, lead investigator on the project. "We could see the changes in crystal structure actually happening while we applied the electric field."

An abstract of the research can be found in a recent issue of the journal Applied Physics Letters.