NANOTUBES IN BORON-NITRIDE LASER-HEATED AT HIGH-PRESSURE

Here we report on the finding of pure boron nitride (BN) nanotubes tha t do not contain any additional inclusions and on a new method for the ir growth: laser heating of boron nitrides at high nitrogen pressure ( 5-15 GPa). The multiwalled nanotubes were observed using high resoluti on electron microscopy and were chemically characterized by electron e nergy loss spectroscopy. The circular or polygonal cross-sectional nan otubes, which have 3-8 shells and a characteristic outer dimension cro ss section of 3-15 nm, were found to have grown either in melted cubic BN or in hexagonal+amorphous BN that had recrystallized on the specim en's surface from the fluid phase. (C) 1996 American Institute of Phys ics.