Martins, Luiz Gustavo PimentaSilva, Diego L.Smith, Jesse S.Lu, Ang-YuSu, CongHempel, MarekOcchialini, ConnorJi, XiangPablo, RicardoAlencar, Rafael SilvaSouza, Alan Custodio dos ReisPinto, Alysson AlvesOliveira, Alan Barros deBatista, Ronaldo Junio CamposPalacios, TomasMazzoni, Mário Sérgio de CarvalhoMatos, Matheus Josué de SouzaComin, RiccardoKong, JingCançado, Luiz Gustavo de Oliveira Lopes2022-03-082022-03-082021MARTINS, L. G. P. et al. Hard, transparent, sp3 -containing 2D phase formed from few-layer graphene under compression. Carbon, v. 173, p. 744-757, 2021. Disponível em: <https://www.sciencedirect.com/science/article/abs/pii/S0008622320311179>. Acesso em: 25 ago. 2021.0008-6223http://www.repositorio.ufop.br/jspui/handle/123456789/14645Despite several theoretically proposed two-dimensional (2D) diamond structures, experimental efforts to obtain such structures are in initial stage. Recent high-pressure experiments provided significant advancements in the field, however, expected properties of a 2D-like diamond such as sp3 content, transparency and hardness, have not been observed together in a compressed graphene system. Here, we compress few-layer graphene samples on SiO2/Si substrate in water and provide experimental evidence for the formation of a quenchable hard, transparent, sp3 -containing 2D phase. Our Raman spectroscopy data indicates phase transition and a surprisingly similar critical pressure for two-, five-layer graphene and graphite in the 4e6 GPa range, as evidenced by changes in several Raman features, combined with a lack of evidence of significant pressure gradients or local non-hydrostatic stress components of the pressure medium up to z 8 GPa. The new phase is transparent and hard, as evidenced from indentation marks on the SiO2 substrate, a material considerably harder than graphene systems. Furthermore, we report the lowest critical pressure (z 4 GPa) in graphite, which we attribute to the role of water in facilitating the phase transition. Theoretical calculations and experimental data indicate a novel, surfaceto-bulk phase transition mechanism that gives hint of diamondene formation.en-USrestritoArtigo publicado em periodicohttps://www.sciencedirect.com/science/article/abs/pii/S0008622320311179https://doi.org/10.1016/j.carbon.2020.11.038