Century-Old Belief About Diamond Overturned After Scientists Discover Something Fascinating

Image Courtesy: SciTechDaily

Diamond, long valued for its unmatched hardness and durability, has revealed a surprising new property. Scientists have discovered that ultrathin diamond membranes can generate electricity when bent, overturning a century-old belief that the material is inherently non-piezoelectric.

The breakthrough was made by researchers at the University of Hong Kong (HKU), led by Professor Zhiqin Chu from the Department of Electrical and Computer Engineering and Professor Yuan Lin from the Department of Mechanical Engineering. By creating an ultrathin, flexible polycrystalline diamond membrane, the team showed that mechanical bending consistently produced measurable electrical voltage.

Piezoelectric materials generate an electric charge when subjected to mechanical stress and are widely used in sensors, actuators, and energy-harvesting devices. For more than 100 years, diamond was considered incapable of exhibiting this behavior despite its exceptional mechanical strength, thermal conductivity, and chemical stability. Instead, it was primarily used as a durable support material in microelectromechanical systems.

To test whether diamond could behave differently at extremely small scales, the HKU team used a recently developed edge-exfoliation technique to produce ultrathin membranes that were flexible enough to bend significantly. Repeated experiments under carefully controlled conditions confirmed that the membranes generated stable and reproducible voltage signals, ruling out electrical effects caused by friction or environmental interference.

Computer simulations revealed that the electrical response originates mainly from asymmetrical grain boundaries, the interfaces where tiny diamond crystals meet within the membrane. As the material bends, electrical charges accumulate along these boundaries, creating a voltage difference between the membrane’s upper and lower surfaces.

The discovery could significantly expand diamond’s role in advanced technology. Because diamond is biocompatible, chemically stable, and non-toxic, the newly discovered piezoelectric effect could enable implantable medical devices that monitor deformation or even generate their own power. Researchers also believe the material could be used in miniature sensors and self-powered energy-harvesting systems that operate without external batteries.