A New Carbon Nitride Phase Synthesized by Shock Compression

To synthesize a carbon nitride with high density existing by theoretical prediction, a series of shock recovery experiments up to 50 GPa were carried out on two nitrogen-rich materials of a C-N-O amorphous precursor and dicyandiamide. The powder X-ray diffractions (XRD) of recovered samples show that the carbon nitride composite phases are formed consisting of -C3N4 and a new crystalline phase. The new phase is indexed as a monoclinic cell with a=0.981 nm, b=0.723 nm, c=0.561 nm, =95.2, and Vcell=0.396 6 nm3. We considered that this new phase is formed to survive as metastable species by extremely high quenching rate (109 K/s) after transient shock-induced reaction of these organic precursors and so shock compression may provide a novel synthesis route for various carbon nitride phases from appropriate rich-nitrogen organic materials.