Discover the Unexpected Resilience of Small-Diameter Diamonds

While diamonds are renowned for their eternal qualities, when reduced to nanoscale dimensions, these crystals exhibit unexpected elasticity. Recent experiments on minuscule diamonds have illuminated what contributes to their surprising flexibility.

According to Chongxin Shan from Zhengzhou University, China, “Bulk diamonds are widely recognized for their extreme stiffness and hardness. However, the properties may differ significantly at the nanoscale.” His team investigated diamonds measuring just 4 nanometers in diameter—hundreds of times smaller than certain viruses—to analyze their behavior under pressure.

The investigation involved sandwiching nanodiamonds between cylinders featuring diamond tips designed for compression. A force sensor measured the drag on the diamonds while a specialized microscope captured their compressed state.

Shan noted the challenges of accurate nanoscale measurements, as minor disturbances can obscure data. To minimize these variables, researchers conducted experiments with approximately 100 distinct diamonds, ensuring a high vacuum environment to eliminate air interference. They discovered that reducing the diamond diameter from 12 nanometers to 4 nanometers resulted in a 30% decrease in stiffness, enhancing elasticity.

By combining experimental data with computer simulation, researchers discerned the underlying mechanics of this phenomenon. Due to their small size, nanodiamonds possess a higher surface-to-core atom ratio, with weak chemical bonds between these regions contributing to increased elasticity. This contrasts with larger diamonds, where stronger core bonds dictate behavior, as explained by Shan.

Yan Lu, a researcher at the City University of Hong Kong, highlighted that these findings reveal unexpected shifts in diamond characteristics compared to earlier investigations. Their work marks a pivotal contribution to understanding nanoscale diamonds, crucial for emerging applications in electronics and quantum technology. “With lab-created diamonds available at lower costs, now is the opportune moment to expand their use,” Lu states.