In 1992 we showed that nanoparticles of the layered compound WS2 are unstable in the platelet form and they spontaneously form closed cage structures akin to carbon fullerenes and carbon nanotubes. This instability was attributed to the highly reactive dangling bonds of both sulfur and tungsten atoms, which appear at the periphery of the nanoparticles.
Numerous kinds of inorganic fullerene-like (IF) nanoparticles and nanotubes (INT) were synthesized by us and by others over the years. Detailed study of the growth mechanism of fullerene-like WS2 nanoparticles and nanotubes was undertaken. This development led to the scaling-up of their production and their recent commercialization by NanoMaterials (www.apnano.com) and N.I.S. (www.nisusacorp.com) as superior solid lubricants with numerous potential applications. A production line for manufacturing lubricants (oils and greases) formulated with these nanoparticles has been recently completed (2014) with sales exceeding 1000 metric tons of lubricants this year.
Much of our efforts today are focused on the synthesis of new nanotubes and fullerene-like nanoparticles and study of their unique physical and chemical behavior. Numerous nanotubes from the large family of “misfit” compounds, like PbS-NbS2 have been recently prepared and studied. Doping of IF-MoS2 nanoparticles with minute amounts of Re and Nb atoms was demonstrated. Precipitous reduction in friction and wear was observed for lubricants formulated with the doped nanoparticles. Various medical applications were proposed for the doped IF nanoparticles.
The microscope image in the header above was produced by Drs. Maya Bar-Sadan and Lothar Houben of the Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons, in Jülich, Germany.