New candidate for the simple cubic carbon sample shock-synthesized by compression of the mixture of carbon black and tetracyanoethylene

Previous experiment of shock compression of the mixture of carbon black and tetracyanoethylene produced clear evidence of a new structural unidentified cubic carbon phase. In this letter, we confirmed that the previously proposed C20-sc and its modifications are more proper than recently suggested BC12 for explaining such a novel simple cubic carbon sample. Most of the X-ray diffraction peaks from the experiment can be understood through the pure C20-sc and some others can be explained by its modifications with introduced interstitial atoms (C21-sc and C22-sc states). Our results also show that C20-sc, C21-sc and C22-sc are all dynamically stable and more favorable than BC12 in energy. Interestingly, we find that C21-sc is a promising superhard carbon conductor, which can be used as multi-functional material in extreme condition. We expect that our discoveries can raise further explorations of this shock-compressing experiment.

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