Closed-cage (fullerene-like) structures of NiBr2

It is well accepted by now that nanoparticles of inorganic layered compounds form closed-cage structures (IF). In particular closed-cage nanoparticles of metal dihalides, like NiCl2, CdCl2 and CdI2 were shown to produce such structures in the past. In the present report IF-NiBr2 polyhedra and quasi-spherical structures were obtained by the evaporation/recrystallization technique as well as by laser ablation. When the nanoclusters were formed in humid atmosphere, nickel perbromate hydrate [Ni(BrO4)2(H2O)6] polyhedra and short tubules were produced, as a result of a reaction with water. Nanooctahedra of NiBr2 were found occasionally in the irradiated soot. The reoccurrence of this structure in the IF family suggests that it is a generic one. Consistent with previous observations, this study showed that formation of the IF materials stabilized the material under the electron-beam irradiation. The growth mechanism of these nanostructures is briefly discussed.