Fluorination and electrical conductivity of BN nanotubes.

Fluorination of BN nanotubes has been performed using a catalytic growth method, which leads to the appearance of markedly curved fluorine-doped BN sheets and converts originally insulating BN nanotubes to semiconductors, as confirmed by the comparative electron transport four-probe measurements on doped and undoped individual BN nanotubes.

Uniform micro-sized alpha- and beta-Si3N4 thin ribbons grown by a high-temperature thermal-decomposition/nitridation route.

Uniform micro-sized alpha- and beta-Si(3)N(4) thin ribbons have been achieved by a high-temperature thermal-decomposition/nitridation route. As-grown ribbons were characterized by using powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and cathodoluminescence. These alpha- and beta-Si(3)N(4) ribbons are structurally uniform micro-sized single crystals, and have a width of approximately 2-3 microns, a thickness of approximately 20-60 nm, and a length, that ranges from several hundreds of microns to the order of millimeters.

Synthesis and field emission of carbon nanotubular fibers doped with high nitrogen content.

Nitrogen-doped carbon nanotubular fibers with a very high nitrogen concentration (approximately 20 at.%) were synthesized through the aerosol-assisted decomposition of dimethylformamide in the presence of catalyst. The synthesized fibers process a novel "pearl necklace-like" morphology and exhibit an excellent field emission performance.

Insulating tubular BN sheathing on semiconducting nanowires.

An effective method was developed for generation of insulating tubular boron nitride (BN)-sheathed nanostructures. ZnS nanowires and multilayered Si-SiO2 nanowires were successfully sheathed with insulating tubular BN-forming nanocables. Both the semiconductor nanowire cores and the BN sheaths are crystalline with well-uniform morphologies.

Formation, structure, and structural properties of a new filamentary tubular form: hollow conical-helix of graphitic boron nitride.

A novel tubular form of graphitic boron nitride (BN) displaying a hollow conical-helix was discovered. It was generated via wrapping a single beltlike filament according to the geometry of an Archimedes spiral. Cone apex angles of helical-conical nanotubes (HCNTs) were found to exhibit specific values, each of which refers to a certain coincidence site lattice.

Structures of a hollow filamentary conical helix.

A hollow conical helix (HCH) of graphitic materials broadens the conical configuration by introduction of wrapping about 120 degrees symmetry positions in addition to the traditional rotation about 60 degrees symmetry sites. Complete structural models are established for a HCH and examined taking into account the rotation mode, coincidence site lattice (CSL), disclination angle and packing pattern. Combined with experimental observations, it is revealed that the size of the CSL, hence the density of the coincidence lattice sites, dominates the overlap configuration of a conical helix.

Single-crystal Al(18)B(4)O(33) microtubes.

Aluminum borate microtubes were prepared in excellent yield by annealing the Al(2)O(3)-NaBH(4)-NiCl(2) starting materials at 1050 degrees C under N(2)(H(2)) atmosphere. The tubes are usually open at each end with the outer diameters narrowly distributed at ca. 1 microm.