RESUMO
Carbon nanotubes (CNTs) are among the most highly studied nanomaterials due to their unique (and intertwined) mechanical and electrical properties. Recent advances in fabrication have allowed devices to be fabricated that are capable of applying a twisting force to individual CNTs while measuring mechanical and electrical response. Here, we review major results from this emerging field of study, revealing new properties of the material itself and opening possibilities for advances in future devices.
Assuntos
Eletricidade , Nanotubos de Carbono , Torção Mecânica , Equipamentos e Provisões Elétricas , Microscopia Eletrônica de TransmissãoRESUMO
Topologically modeled amorphized silica structures have been refined using a molecular dynamics simulation technique. Several metastable structures with substantially different medium-range connectivities, as characterized by primitive ring statistics, were obtained. Whereas the total correlation function is insensitive to these differences, the first step diffraction peak derived from energy-filtered electron diffraction shows a promising correlation to medium-range structure.
Assuntos
Dióxido de Silício/química , Cristalização , Microscopia Eletrônica , Modelos Moleculares , Nanotecnologia/métodos , Difração de Raios XRESUMO
We have synthesized novel crystalline ropes of "polygonized" single-wall carbon nanotubes (SWCNTs). The tubes exhibit rounded-hexagonal cross sections in contrast to the earlier observations of nearly circular tubes. To investigate the structural characteristics of the lattice of SWCNTs we have performed extensive molecular-dynamics simulations. We find several metastable structures of the lattice characterized by different tube cross sections, hexagonal, rounded-hexagonal, and circular, and increasing cell volume. The competition between different tube shapes as a function of tube diameter is analyzed and compared to experiments.
