Cn Superhard Materials Explosive Shock Compression Synthesis Research

:Carbon nitride materials predicted by theoretic calculating may have excellentpropertied in mechanics, electricity and photics. The research on syntheses and properties ofcarbon nitride materials is interesting for scholars from different countries. Carbon nitridematerials with particular properties has been synthesized. The properties such as highhardness, low friction coefficient, excellent wearability and photics properties, can providethe profound foundation for the application of carbon nitride materials in many fields. In thisthesis, we concentrate on the development in theoretical prediction and experimentalsynthesis of CN compounds in the recent 10 years. By means of shack wave synthesis, weexplore the routes to synthesize carbon nitrides. The chemical compositions, crystal structuresand bonding states of the CN powders obtained from the experiment are studied by the useof EDX, XRD, SEM and FTIR.To synthesize a carbon nitride with high density existing by theoretical prediction ,a seriesof shock recovery experiments using RDX up to 6～18 GPa were carried out on threenitrogen-rich materials of a 5-Aminotetrazole precursor,dicyandiamide and sodiumdicyanamide mixed with sodium azide and carbon tetra-iodide. FTIR analysis of therecovered shock-compressed residue showed crystallites of a C-N compound and haven'tfounded C≡N and C=N .The powder X-ray diffractions (XRD) of recovered samples showthat t he carbon nit ride composite phases are formed consisting ofα-,β-C3N4 and a few ofCNx phase and graphite-C3N4 phase. We considered that t his new phase is formed to surviveas metastable species by extremely high quenching rate (≈109 K/ s) after transient shockinducedreaction of these organic precursors and so shock compression may provide a novelsynthesis route for various carbon nitride phases from appropriate rich-nitrogen organicmaterials.