Research published today by materials engineers from the University of Leeds could help pave the way towards 100% lead-free electronics.
The work, carried out at the UK's synchrotron facility, Diamond Light Source, reveals the potential of a new manmade material to replace lead-based ceramics in countless electronic devices, ranging from inkjet printers and digital cameras to hospital ultrasound scanners and diesel fuel injectors.
European regulations now bar the use of most lead-containing materials in electronic and electrical devices. Ceramic crystals known as 'piezoelectrics' are currently exempt from these regulations but this may change in the future, owing to growing concerns over the disposal of lead-based materials.
Piezoelectric materials generate an electrical field when pressure is applied, and vice-versa. In gas igniters on ovens and fires, for example, piezoelectric crystals produce a high voltage when they are hit with a spring-loaded hammer, generating a spark across a small gap that lights the fuel.
The most common piezoelectric material is a ceramic crystal called lead zirconium titanate, or PZT.
Using a high intensity X-ray beam at the Diamond Light Source, the University of Leeds researchers have now shown that a simple, lead-free ceramic could potentially do the same job as PZT.
"With the 'Extreme Conditions' beamline at Diamond we were able to probe the interior of the lead-free ceramic- potassium sodium bismuth titanate (KNBT) to learn more about its piezoelectric properties. We could see the changes in crystal structure actually happening while we applied the electric field," said Tim Comyn, lead investigator on the project."
"PZT is the best material for the job at the moment, because it has the greatest piezoelectric effect, good physical durability, and can be radically tailored to suit particular applications," said Adam Royles, PhD student on the project. "The lead-free ceramic that we have been studying is lightweight and can be used at room temperature. This could make it an ideal choice for many applications."
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.
The Leeds team will continue to work at Diamond to study the transformation induced by an electric field at high speed (1000 times per second) and under various conditions using state of the art detectors.
The results of the work are published online in the journal Applied Physics Letters.
For further information: Paula Gould, University of Leeds press office: Tel 0113 343 8059, email p.a.gould@leeds.ac.uk
Sarah Boundy, Diamond Light Source: Tel 01235 778639/07920 296957, email sarah.boundy@diamond.ac.uk
Silvana Westbury, Diamond Light Source: Tel 01235 778238/07841 432780, email silvana.westbury@diamond.ac.uk
Notes to Editors
1. The paper, 'Electric- field-induced phase switching in the lead free piezoelectric potassium sodium bismuth titanate ', is available online in the journal Applied Physics Letters (doi: 10.1063/1.3490235).
2. The 2008 Research Assessment Exercise showed the University of Leeds to be the UK's eighth biggest research powerhouse. The University is one of the largest higher education institutions in the UK and a member of the Russell Group of research-intensive universities. The University's vision is to secure a place among the world's top 50 by 2015. www.leeds.ac.uk
3. The Faculty of Engineering at the University of Leeds is ranked 7th in the UK for the quality of its research (2008 Research Assessment Exercise); an impressive 75% of the Faculty's research activity rated as internationally excellent or world leading. With 700 academic and research staff and 3,000 students the Faculty is a major player in the field with a track record of experience across the full spectrum of the engineering and computing disciplines. The Faculty of Engineering is home to five schools: civil engineering; computing; electronic and electrical engineering; mechanical engineering; process, environmental and materials engineering. www.engineering.leeds.ac.uk
4. Diamond Light Source is funded by the UK Government via the Science and Technology Facilities Council (STFC) and by the Wellcome Trust. www.diamond.ac.uk
Diamond generates extremely intense pin-point beams of synchrotron light of exceptional quality ranging from x-rays, ultra-violet and infrared. For example Diamond's X-rays are around 100 billion times brighter than a standard hospital X-ray machine or 10 billion times brighter than the sun. Many of our everyday commodities that we take for granted, from food manufacturing to cosmetics, from revolutionary drugs to surgical tools, from computers to mobile phones, have all been developed or improved using synchrotron light.
Diamond brings benefits to:
- Biology and medicine. For example, the fight against illnesses such as Parkinson's, Alzheimer's, osteoporosis and many cancers will benefit from the new research techniques available at Diamond.
- The physical and chemical sciences. For example, in the near future, engineers will be able to image their structure down to an atomic scale, helping them to understand the way impurities and defects behave and how they can be controlled.
- The Environmental and Earth sciences. For example, Diamond helps researchers to identify organisms that target specific types of contaminant in the environment which can potentially lead to identifying cheap and effective ways for cleaning polluted land.
Journal
Applied Physics Letters