Structure and phase characteristics of amorphous boron-carbon-nitrogen under high pressure and high temperature

摘要

An amorphous boron-carbon-nitrogen (a-BCN) phase was synthesized by ball milling of a mixture of hexagonal BN (h-BN) and graphite with a nominal composition of (BN)_0.5C_0.5 in atomic ratio. Electron energy-loss spectroscopy studies indicated that the bonding of the a-BCN is in an sp~2 configuration and the mixing between the BN and the C species was achieved at a nanometer scale, but the a-BCN phase was more likely a mechanical mixture rather than a chemical mixture. High-pressure and high-temperature (HPHT) treatment at 7.7 Gpa and 2300deg.C of the a-BCN phase resulted in complete segregation of the carbon and BN species, forming a nanocrystalline composite material comprising cubic BN (c-BN), amorphous carbon, and turbostratic graphite.