Synthesis, Atomic Structures, and Electronic States of Boron Nitride Nanocage Clusters and Nanotubes

Abstract

Boron nitride (BN) nanocage clusters (B n N n : n = 12–60), endohedral BN clusters Y@B n N n , and BN nanotubes were synthesized by an arc-melting method, and characterized by mass spectrometry and high-resolution electron microscopy. The BN clusters consisted of 4-, 6-, 8-, and 10-membered BN rings satisfying the isolated tetragonal rule, which was optimized by molecular orbital calculations. Total energy calculation showed that some elements stabilize and expand the B36N36 structure. Bandgap energies of the B36N36 clusters were found to be reduced by introducing a metal atom inside the cluster, which indicates controllability of the energy gap. Chiralities of BN nanotubes with zigzag- and armchair-type structures were directly determined from high-resolution images, and structure models are proposed. Total energies of BN nanotubes with a zigzag-type structure were lower than those of armchair-type structure, and these results agreed well with the experimental data of disordered tube structure. BN nanotubes encapsulating BN clusters and a yttrium nanowire were also found. This article indicates that the new BN nanocage fullerene materials with various atomic structures and properties can be produced, and a guideline for designing the BN fullerene materials is summarized.