Ultrafine diamond synthesized by long-pulse-width laser

Abstract

Nanodiamonds with sizes of 3–6nm were prepared by irradiating graphite suspension using a long-pulse-width (1.2ms) laser at room temperature and normal pressure. The low power density and long pulse laser generated a lower temperature and a lower pressure, which determine the stable size of nanodiamonds. On the other hand, the low degree of supercooling allows a rather low growth velocity, and a disordered structure formed at the diamond surface retards the epitaxy growth. The above two factors dynamically limit the final size of nanodiamonds. Our results suggest that the growth of nanodiamonds follows the Wilson-Frenkel law, and the long pulse laser is propitious to producing fine nanodiamonds.