We unveil the diamondization mechanism of few-layer graphene compressed in the presence of water, providing robust evidence for the pressure-induced formation of 2D diamond. High-pressure Raman spectroscopy provides evidence of a phase transition occurring in the range of 4-7 GPa for 5-layer graphene and graphite. The pressure-induced phase is partially transparent and indents the silicon substrate. Our combined theoretical and experimental results indicate a gradual top-bottom diamondization mechanism, consistent with the formation of diamondene, a 2D ferromagnetic semiconductor. High-pressure x-ray diffraction on graphene indicates the formation of hexagonal diamond, consistent with the bulk limit of eclipsed-conformed diamondene.
@article{arxiv.1910.01591,
title = {Evidence for a pressure-induced phase transition of few-layer graphene to 2D diamond},
author = {Luiz G. Pimenta Martins and Diego L. Silva and Jesse S. Smith and Ang-Yu Lu and Cong Su and Marek Hempel and Connor Occhialini and Xiang Ji and Ricardo Pablo and Rafael S. Alencar and Alan C. R. Souza and Alan B. de Oliveira and Ronaldo J. C. Batista and Tomás Palacios and Matheus J. S. Matos and Mário S. C. Mazzoni and Riccardo Comin and Jing Kong and Luiz G. Cançado},
journal= {arXiv preprint arXiv:1910.01591},
year = {2019}
}