Structure of twisted BNC nanotubes with polygonal cross-section

摘要

BNC nanotubes and nanofibers have been synthesized in the high isostatic pressure apparatus in Ar at 1923 K and 1.5 MPa in the presence of yttrium aluminium garnet. Some of the nanotubes obtained were filled with A1 _2O _3. Transmission electron microscopy (TEM) studies have shown that the nanotubes and nanofibers have a polygonal cross-section (prismatic shape), and most often they are twisted, which is due to the transversal instability of the nanotubes originating under the growth conditions, including temperature treatment. Twisting also revealed itself in the appearance of the moiré fringes during the TEM observation of some of the nanotubes and nanofibers. Analysis of these fringes has shown that the facets of these nanotubes represent the slightly misoriented hexagonal BN and/or C plates. An A1 _2O _3 filling of the nanotube makes it harder to twist when subjected to torque, which conforms to the tube deformation theory.