Nanodiamond clusters and their tranformation into fullerene at high temperature: A tight-binding simulation

Small nanodiamonds (22-172 atoms) of various shapes were studied by tight-binding molecular dynamics. It was found that spherical and cubic nanodiamonds with number of atoms more than 40 formed closed-shaped fullerene-like structures under graduate heating. The smallest fullerene-like structure obtained in the simulations contained 35 atoms. One of the observed fullerenes was an isomer of the C₆₀ fullerene and had a shape which is close to spherical one. The temperature and the time of the transformation depended on the size of the nanodiamod. The heating and cooling rate also influenced the final structure and a number of distortions in the final fullerene. The mechanism of the transformation was studied. Stability of the fullerenes was confirmed by DFT optimization. Diamond nanowires of 5-8 ¿ in diameter also can transform into damaged CNT under heating.