Superior Hardness and Stiffness of Diamond Nanoparticles

TL;DR

This paper presents a computational method using ab initio calculations to estimate the hardness and stiffness of diamond nanoparticles, revealing bond stiffening effects due to surface tension and compression.

Contribution

It introduces a novel computational approach to analyze the elastic properties of diamond surfaces and nanoparticles, explaining hardness variations through atomic-scale bond stiffening mechanisms.

Findings

Bond stiffening in diamond surfaces explained by atomic compression.

Surface tension drives bond length reduction in nanoscale diamonds.

Hardness differences linked to atomic-scale elastic response.

Abstract

We introduce a computational approach to estimate the hardness and stiffness of diamond surfaces and nanoparticles by studying their elastic response to atomic nanoindentation. Results of our ab initio density functional calculations explain the observed hardness differences between different diamond surfaces and suggest bond stiffening in bare and hydrogenated fragments of cubic diamond and lonsdaleite. The increase in hardness and stiffness can be traced back to bond length reduction especially in bare nanoscale diamond clusters, a result of compression that is driven by the dominant role of the surface tension.