Nanotubes in boron nitride laser heated at high pressure

Here we report on the finding of pure boron nitride (BN) nanotubes that do not contain any additional inclusions and on a new method for their growth: laser heating of boron nitrides at high nitrogen pressure (5-15 GPa). The multiwalled nanotubes were observed using high resolution electron microscopy and were chemically characterized by electron energy loss spectroscopy. The circular or polygonal cross-sectional nanotubes, which have 3-8 shells and a characteristic outer dimension cross 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 specimen's surface from the fluid phase. (C) 1996 American Institute of Physics.