Pressure Synthesis of Ultrahard Carbon Nitrides

The search for materials harder than diamonds is one of the holy grails of material sciences. Many candidate compounds have been suggested and carbon nitrides are among the most compelling.1,2 As it stands, none of the high-pressure experiments on the C-N system resulted in the full structural determination of a new carbon nitride. Here, we propose to employ the extremely powerful method of single-crystal X-ray diffraction of a polycrystalline sample (SC-XRDp) to characterize the reaction products of a laser-heated carbon-nitrogen precursor, tetracyanoethylene (TCNE, C6N4), between 20 and 130 GPa. The compressibility and stability range of the produced carbon nitrides will be determined. Preliminary experiments show the synthesis of a new compound.