SIZE EVOLUTION OF NANOCLUSTERS: COMPARISON BETWEEN THE PHASE DIAGRAM AND PROPERTIES OF Mo–S AND CARBON NANOPARTICLES

摘要

In this article a comparison between inorganic nanoparticles with hollow closed structure and the carbon fullerenes and nanotubes is undertaken. First, the structural evolution of inorganic fullerene-like (IF) nanoparticles of MoS_2 as a function of their size is examined in some detail and compared to that of carbon and BN fullerenes. It is shown that hollow closed structures of MoS_2 are stable above 3 nm (app 10~3 atoms). In the range of 3-8 nm (10~3-10~5) nanooctahedra with metallic character are the most stable form of MoS_2 Semiconducting nanotubes and quasispherical IF nano-particles become the stable-most form beyond that size and the bulk (platelets) are stable above about 0.2 μm. The stability of inorganic nanotubes is also discussed. The scaling-up of the synthesis of IF-WS_2 and the very recent successful synthesis of large, amounts of pure WS_2 nanotubes are briefly described. The stability of IF and INT of MoS_2 (WS_2) under pressure and that of carbon is also discussed. Applications of the IF-WS_2 as superior solid lubricants, which lead to their recent commercialization, is demonstrated.