Charge distributions in BN nanocones: electric field and tip termination effects

The electronic charge distributions in boron-nitride nanocones with 240degrees disclination are investigated through first-principles calculations based on the density-functional theory. The charge distributions in BN cones are analyzed and compared with a planar BN sheet and BN nanotubes. The cones are submitted to different external electric fields applied along the axis, ranging from 0 up to 1.7 V/Angstrom, and the charge rearrangements are studied. The tip charge concentrations and the electronic behaviors of these cones show different characteristics depending on the terminating atoms. The cone's particular structure and the response to the electric field make the BN cones promising candidates to be used as probes in electronic microscopy as well as electron field emitters. (C) 2004 Elsevier B.V. All rights reserved.