Chemical Synthesis of Graphite-Like B/C/N Materials Leading to the Shock Synthesis of the Heterodiamond

Graphite-like B/C/N materials, g-BCxN, are chemically prepared in very high yields using a polymer pyrolysis system of boron trichloride and commercially available N-containing materials such as tetracyanoethylene and polyacrylonitrile. Using the g-BCxN materials, a series of new diamond materials, B/C/N heterodiamond, are shock-synthesized. The Lewis acid-base reaction initially occurs between BCl3 gas and the basic organic compounds, is followed by polymerization, carbonization and heat-treatment. The g-BCxN materials over the almost entire range of compositions can be prepared: the g-BC3N material is obtained in ca 75 % yield from polyacrylonitrile, and the g-BC4N is in nearly 100 % yield from tetracyanoethylene. The materials have a miscible blend (hybrid) structure consisting of CNx and (BN)y segments and have turbostatic hexagonal structures similar to the structure of the chemical vapor deposition g-BC2N. The g-BCxN materials obtained are explosively shock-compressed and successfully phase-transformed into their almost allotropic heterodiamond materials.