Q-carbon harder than diamond


A new phase of carbon named Q-carbon is found to be over 40% harder than diamond. This phase is formed by nanosecond laser melting of amorphous carbon and rapid quenching from the super-undercooled state. Closely packed atoms in molten metallic carbon are quenched into Q-carbon with 80-85% sp3 and the rest sp2. The number density of atoms in Q-carbon can vary from 40% to 60% higher than diamond cubic lattice, as the tetrahedra packing efficiency increases from 70% to 80%. Using this semiempirical approach, the corresponding increase in Q-carbon hardness is estimated to vary from 48% to 70% compared to diamond.

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We are grateful to Fan Family Foundation Distinguished Chair Endowment for J. Narayan. R. Sachan acknowledges the National Academy of Sciences (NAS), USA for awarding the NRC research fellowship. This work was performed under the National Science Foundation (Award number DMR-1735695). We used Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina. Filippo Cellini and Elisa Riedo acknowledge the support from the Office of Basic Energy Sciences of the US Department of Energy (grant no. DE-SC0016204).

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Correspondence to Jagdish Narayan.


Supplementary materials

The supplementary material for this article can be found at https://doi.org/10.1557/mrc.2018.35.

Author contributions

J. N. conceived and designed the theory and wrote the manuscript with inputs from all the co-authors. S. G. and A. B. synthesized the samples and performed the Raman spec-troscopy, SEM, and HR-TEM imaging. R. S. performed electron microscopic imaging and EEL spectroscopy. F. C. and E. R. performed the performed AFM imaging and nanome-chanics experiments.

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The authors declare no competing financial interests.

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The authors declare no competing financial interest.

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Narayan, J., Gupta, S., Sachan, R. et al. Q-carbon harder than diamond. MRS Communications 8, 428–436 (2018). https://doi.org/10.1557/mrc.2018.35

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