Researchers discover potential of lead-free piezoelectric ceramics

October 4, 2010
Crystal structure of KNBT before the application of an electric field (left) and after (right). The purple spheres are either sodium or potassium atoms, the red spheres are oxygen atoms, the small blue sphere is titanium. The figures show the arrangement of the atoms changing from rhombohedral, where the a, b and c axes are of the same length and rhombohedral angle is less than 90, to tetragonal symmetry, where the a and b axes are of the same length and the c axis is longer.

Scientists are using Diamond Light Source, the UK’s national synchrotron facility, to discover how we can detoxify our electronic gadgets. Results published in the journal Applied Physics Letters on 1st October reveal the potential for new artificial materials that could replace lead-based components in everyday products from inkjet printers to digital cameras.

Researchers from the Institute for Materials Research at the University of Leeds’ Faculty of Engineering used the Diamond synchrotron to investigate the structure and properties of piezoelectric ceramics in order to develop more environmentally friendly alternatives to the widely-used but toxic ceramic crystal lead zirconium titanate (PZT).

The team used the I15 Extreme Conditions beamline at Diamond to probe the interior crystal structure of the ceramics with a high-energy pinpoint X-ray beam and saw changes in the crystal structure as an electric field was applied. Their results demonstrate that this new material, potassium sodium bismuth titanate (KNBT), shows the potential to perform the same job as its lead counterpart.

"These results are very encouraging. Although harmless when in use, at the end of their lifetime these PZT gadgets have to be carefully disposed of due to their lead content and as a consequence, there is significant interest in developing lead-free ceramics," said Dr Tim Comyn, University of Leeds scientist.

Piezoelectric materials generate an electrical field when pressure is applied, and vice versa. For example in gas igniters, like those used on ovens and fires, a piezoelectric crystal creates sparks when hit with the hammer. In an electrical field, it undergoes a phase transition, that is changes in the crystal structure.

The team will continue to work at Diamond to study the electric field induced transformation at high speed (1000 times per second) and under various conditions using state of the art detectors.

"Not only could a lead-free solution mean safer disposal of electronic equipment, by virtue of the absence of lead, these new materials are far lighter than PZT. The piezoelectric market has applications in many fields, where a lighter lead-free alternative could make quite a difference." said Adam Royles, University of Leeds researcher.

In the medical field, PZT is used in ultrasound transducers, where it generates sound waves and sends the echoes to a computer to convert into a picture. Piezoelectric ceramics also hold great potential for efficient energy harvesting, a possible solution for a clean sustainable energy source in the future.

Lead-based electronic ceramics are one of only a few exemptions to the European directive on the restriction of the use of certain hazardous substances in electrical and electronic components (2002/95/EC). This exemption will be reviewed again in 2012.
The global market for piezoelectric-operated actuators and motors was estimated to be $6.6 billion in 2009 and is estimated to reach $12.3 billion by 2014.

Explore further: Materials Advances: Holey Ceramics

More information: Electric-field-induced phase switching in the lead free piezoelectric potassium sodium bismuth titanate. A.J. Royles, A.J. Bell, A.P. Jephcoat, A.K. Kleppe, S.J. Milne and T.P. Comyn. Applied Physics Letters. (Vol.97, Issue 13). DOI: 10.1063/1.3490235

Related Stories

Materials Advances: Holey Ceramics

July 2, 2004

Unique material is designed by Rostov scientists supported by the Russian Foundation for Basic Research (RFBR) and Foundation for Assistance to Small Innovative Enterprises (FASIE). This is a porous ceramic for a piezotransformer ...

Modern ceramics help advance technology

May 8, 2008

Many important electronic devices used by people today would be impossible without the use of ceramics. A new study published in the Journal of the American Ceramic Society illustrates the use of ceramic materials in the ...

Researchers take the lead out of piezoelectrics

November 13, 2009

There is good news for the global effort to reduce the amount of lead in the environment and for the growing array of technologies that rely upon the piezoelectric effect. A lead-free alternative to the current crop of piezoelectric ...

Lead-free piezoelectric materials of the future

September 14, 2010

Piezoelectric materials have fantastic properties: squeeze them and they generate an electrical field. And vice-versa, they contract or expand when jolted with an electrical pulse. With a name derived from the Greek word ...

Recommended for you

Turbulence in bacterial cultures

November 30, 2015

Turbulent flows surround us, from complex cloud formations to rapidly flowing rivers. Populations of motile bacteria in liquid media can also exhibit patterns of collective motion that resemble turbulent flows, provided the ...

Test racetrack dipole magnet produces record 16 tesla field

November 30, 2015

A new world record has been broken by the CERN magnet group when their racetrack test magnet produced a 16.2 tesla (16.2T) peak field – nearly twice that produced by the current LHC dipoles and the highest ever for a dipole ...

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.