A new carbon nitride synthesized by shock compression of organic precursors

A series of shock recovery experiments up to similar to 50 GPa were carried Out on three nitrogen-rich materials of a C-N-O amorphous precursor, dicyandiamide and melamine. The powder X-ray diffractions (XRD) of recovered samples show that carbon nitride phases are formed. They are beta-C3N4 and a new crystalline phase. The new phase is indexed as a monoclinic cell with a = 0.981 run, b = 0.723 run, c = 0.561 nm, beta = 95.2 degrees and V-cell = 0.3966 nm(3). Melamine was very stable and did not decompose up to similar to 37 GPa. This new phase is considered to form during the adiabatic release process with an extremely high quenching rate (similar to 10(9) K/s) and shock compression may provide a novel synthesis route for various C-N phases from appropriate organic materials. (c) 2005 Elsevier Ltd. All rights reserved.