Research on nanodiamonds demonstrates that they are less rigid compared to larger diamonds, enhancing knowledge of their potential in emerging technologies.
Diamonds are renowned for their durability, yet when reduced to extremely small sizes, they display increased flexibility. A study examining some of the tiniest diamonds ever analyzed explains this phenomenon.
Bulk diamonds are famous for their exceptional rigidity and toughness. However, at the nanoscale, their behavior shifts, according to Chongxin Shan from Zhengzhou University in China. Shan and his team investigated diamonds measuring just 4 nanometers in width—far smaller than many viruses—and observed their response to applied force.
The scientists positioned each nanodiamond between two diamond-tipped cylinders designed to apply pressure. These cylinders linked to a sensor that gauged resistance and a specialized microscope that captured images of the compression process.
Shan notes that obtaining accurate data at such small scales is difficult due to minimal effects and potential interference from surroundings. To address this, the team tested around 100 diamonds and conducted experiments in a high-vacuum environment to eliminate air particle disruptions. Results showed that as diamond size dropped from 12 to 4 nanometers, stiffness reduced by approximately 30 percent, increasing elasticity.
Using these findings and computational models, the researchers determined the cause. Shan explains that in such tiny diamonds, the proportion of surface atoms to core atoms is high, with weaker bonds between these areas. This leads to greater flexibility than in larger diamonds, where the core’s stronger bonds prevail due to a lower surface-to-core ratio.
Yang Lu from the City University of Hong Kong comments that this study reveals surprising alterations in diamond characteristics, surpassing previous research on small diamonds. His group conducted early work showing reduced hardness and brittleness in nanoscale diamonds, but the current effort examined sizes ten times smaller. Lu emphasizes the growing use of tiny diamonds in innovative electronics and quantum technologies, noting that synthetic diamonds are now inexpensive, facilitating broader applications.
