Authors: A.V. Henkes, F. Fantuzzi, M.A.C. Nascimento
Affilation: Instituto de Química, Universidade Federal do Rio de Janeiro, Brazil
Pages: 387 - 390
Keywords: nanotubes, alkali halides, nanostructures, quantum dynamics
Results of accurate quantum-mechanical calculations for alkali halide nanoclusters (LiF, NaCl, KBr), revealed a variety of new morphologies - single and multiple tubes, double-sheets, honeycomb, sodalitic cages- quite distinct from the cubic macro crystal structure. The nanotubes are quite regular structures with a constant distance between adjacent rings along the tube and a slightly smaller external diameter. The internal diameters of the nanotubes are much smaller [between 0.241nm (LiF tetragonal) and 0.67nm (KBr hexagonal)] than the traditional covalent nanotubes of C (1-2nm), BN (1-3nm) and GaN (30-200nm). Quantum dynamics calculations indicate that small ring structures will be formed preferentially to the cubic-like and that nanotubes with octogonal cross-section are more stable than the typical cubic structures for this class of compounds. Although the larger tubes are less stable than the cubic isomers, the formation of the nanotubes appear to be kinetically controlled and the barriers of interconversion from the tubes to the corresponding cubic structures are apparently large. Thus, the calculations predict that the tube-like structures should be stable enough to allow for their isolation and characterization. These stable tubular structures may find important applications as ion pumps in Li+ and/or F- batteries.