Ergun, S. & Alexander, L. E. Crystalline forms of carbon: a possible hexagonal polymorph of diamond. Nature 195, 765–767 (1962).
E. I. du Pont de Nemours and Company. Netherlands Patent Release No. 6506395 (22 November 1965).
Hanneman, R. E., Strong, H. M. & Bundy, F. P. Hexagonal diamonds in meteorites: implications. Science 155, 995–997 (1967).
Shiell, T. B. et al. Nanocrystalline hexagonal diamond formed from glassy carbon. Sci. Rep. 6, 37232 (2016).
Prawer, S. & Greentree, A. D. Diamond for quantum computing. Science 320, 1601–1602 (2008).
Aharonovich, I., Greentree, A. D. & Prawer, S. Diamond photonics. Nat. Photon. 5, 397–405 (2011).
Frondel, C. & Marvin, U. B. Lonsdaleite, a hexagonal polymorph of diamond. Nature 214, 587–589 (1967).
Pan, Z., Sun, H., Zhang, Y. & Chen, C. Harder than diamond: superior indentation strength of wurtzite BN and lonsdaleite. Phys. Rev. Lett. 102, 055503 (2009).
Kraus, D. et al. Nanosecond formation of diamond and lonsdaleite by shock compression of graphite. Nat. Commun. 7, 10970 (2016).
Utsumi, W. & Yagi, T. Formation of hexagonal diamond by room temperature compression of graphite. Proc. Jpn. Acad. B 67, 159–164 (1991).
Yagi, T., Utsumi, W., Yamakata, M., Kikegawa, T. & Shimomura, O. High-pressure in situ x-ray-diffraction study of the phase transformation from graphite to hexagonal diamond at room temperature. Phys. Rev. B 46, 6031–6039 (1992).
Bundy, F. P. & Kasper, J. S. Hexagonal diamond—a new form of carbon. J. Chem. Phys. 46, 3437–3446 (1967).
Stavrou, E. et al. Detonation-induced transformation of graphite to hexagonal diamond. Phys. Rev. B 102, 104116 (2020).
Turneaure, S. J., Sharma, S. M., Volz, T. J., Winey, J. M. & Gupta, Y. M. Transformation of shock-compressed graphite to hexagonal diamond in nanoseconds. Sci. Adv. 3, eaao3561 (2017).
Volz, T. J. & Gupta, Y. M. Elastic moduli of hexagonal diamond and cubic diamond formed under shock compression. Phys. Rev. B 103, L100101 (2021).
Baek, W. et al. Unique nanomechanical properties of diamond–lonsdaleite biphases: combined experimental and theoretical consideration of Popigai impact diamonds. Nano Lett. 19, 1570–1576 (2019).
Németh, P. et al. Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material. Nat. Commun. 5, 5447 (2014).
Murri, M. et al. Quantifying hexagonal stacking in diamond. Sci. Rep. 9, 10334 (2019).
Németh, P. et al. Complex nanostructures in diamond. Nat. Mater. 19, 1126–1131 (2020).
Luo, K. et al. Coherent interfaces govern direct transformation from graphite to diamond. Nature 607, 486–491 (2022).
Luo, D. et al. Atomistic evidence of nucleation mechanism for the direct graphite-to-diamond transformation. Carbon 229, 119538 (2024).
Smith, D. C. & Godard, G. UV and VIS Raman spectra of natural lonsdaleites: towards a recognised standard. Spectrochim. Acta A 73, 428–435 (2009).
Ferrari, A., Robertson, J., Reich, S. & Thomsen, C. Raman spectroscopy of graphite. Philos. Trans. R. Soc. A 362, 2271–2288 (2004).
Cui, H.-J. et al. Diamond polytypes under high pressure: a first-principles study. Comput. Mater. Sci. 98, 129–135 (2015).
Flores-Livas, J. A. et al. Raman activity of sp3 carbon allotropes under pressure: a density functional theory study. Phys. Rev. B 85, 155428 (2012).
Kanasaki, J., Inami, E., Tanimura, K., Ohnishi, H. & Nasu, K. Formation of sp3-bonded carbon nanostructures by femtosecond laser excitation of graphite. Phys. Rev. Lett. 102, 087402 (2009).
Mao, W. L. et al. Bonding changes in compressed superhard graphite. Science 302, 425–427 (2003).
Huang, Q. et al. Nanotwinned diamond with unprecedented hardness and stability. Nature 510, 250–253 (2014).
Garvie, L. A. J., Németh, P. & Buseck, P. R. Transformation of graphite to diamond via a topotactic mechanism. Am. Mineral. 99, 531–538 (2014).
Németh, P. et al. Diamond-graphene composite nanostructures. Nano Lett. 20, 3611–3619 (2020).
Németh, P. et al. Diaphite-structured nanodiamonds with six- and twelve-fold symmetries. Diam. Relat. Mater. 119, 108573 (2021).
Volz, T. J., Turneaure, S. J., Sharma, S. M. & Gupta, Y. M. Role of graphite crystal structure on the shock-induced formation of cubic and hexagonal diamond. Phys. Rev. B 101, 224109 (2020).
Hrubiak, R., Sinogeikin, S., Rod, E. & Shen, G. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team. Rev. Sci. Instrum. 86, 072202 (2015).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).
Wan, L. & Egerton, R. F. Preparation and characterization of carbon nitride thin films. Thin Solid Films 279, 34–42 (1996).
