Lead-free piezoelectric material turns motion into power
The soft, hybrid material reportedly rivals the performance of traditional lead-based ceramics.
A crystal of the newly discovered piezoelectric material viewed under a microscope
© University of Birmingham/University of OxfordA team from the Universities of Birmingham, Oxford and Bristol, UK, describe a material that is both durable and sensitive to movement, with potential for sensors, wearable electronics and self-powered devices.
Based on bismuth iodide, an inorganic salt with low toxicity, the material reportedly offers lower toxicity and easier processing than lead-based materials like PZT (lead zirconate titanate), which is 60% lead.
The new material can also be produced at room temperature rather than 1,000°C.
Piezoelectric materials generate electric charge when pressed or bent and can also deform when an electric field is applied.
Researchers at the University of Birmingham used single-crystal X-ray diffraction and solid-state nuclear magnetic resonance to understand the material’s behaviour.
They have found that the way organic and inorganic parts stick together through halogen bonding can be used to change when and how the material changes its structure, as well as improving piezoelectric performance.
Lead author Dr Esther Hung, from the University of Oxford, who led the research, says, ‘By fine-tuning the interactions between the organic and inorganic components, we were able to create a delicate structural instability that breaks symmetry in just the right way.
‘This interplay between order and disorder is what gives the material its exceptional piezoelectric response. It’s a different approach to piezoelectricity than in traditional materials such as PZT, and that’s what’s led to these big improvements.’
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