Browsing by Author "Mazzoni, Mario Sergio de Carvalho"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Compression induced modification of boron nitride layers : a conductive two-dimensional BN compound.
    (2019) Barboza, Ana Paula Moreira; Matos, Matheus Josué de Souza; Chacham, Helio; Batista, Ronaldo Junio Campos; Oliveira, Alan Barros de; Mazzoni, Mario Sergio de Carvalho; Neves, Bernardo Ruegger Almeida
    The ability of creating materials with improved properties upon transformation processes applied to conventional materials is the keystone of materials science. Here, hexagonal boron nitride (h-BN), a large bandgap insulator, is transformed into a conductive two-dimensional (2D) material – bonitrol – that is stable at ambient conditions. The process, which requires compression of at least two h-BN layers and hydroxyl ions, is characterized via scanning probe microscopy experiments and ab initio calculations. This material and its creation mechanism represent an additional strategy on the transformation of known 2D materials into artificial advanced materials with exceptional properties
  • No Thumbnail Available
    Item
    Raman evidence for pressure-induced formation of diamondene.
    (2017) Martins, Luiz Gustavo Pimenta; Matos, Matheus Josué de Souza; Paschoal, Alexandre R.; Freire, Paulo T. C.; Andrade, Nádia Ferreira de; Aguiar, Acrisio Lins de; Kong, Jing; Neves, Bernardo Ruegger Almeida; Oliveira, Alan Barros de; Mazzoni, Mario Sergio de Carvalho; Souza Filho, Antonio Gomes; Cançado, Luiz Gustavo de Oliveira Lopes
    Despite the advanced stage of diamond thin-film technology, with applications ranging from superconductivity to biosensing, the realization of a stable and atomically thick two-dimensional diamond material, named here as diamondene, is still forthcoming. Adding to the outstanding properties of its bulk and thin-film counterparts, diamondene is predicted to be a ferromagnetic semiconductor with spin polarized bands. Here, we provide spectroscopic evidence for the formation of diamondene by performing Raman spectroscopy of double-layer graphene under high pressure. The results are explained in terms of a breakdown in the Kohn anomaly associated with the finite size of the remaining graphene sites surrounded by the diamondene matrix. Ab initio calculations and molecular dynamics simulations are employed to clarify the mechanism of diamondene formation, which requires two or more layers of graphene subjected to high pressures in the presence of specific chemical groups such as hydroxyl groups or hydrogens.
  • No Thumbnail Available
    Item
    Room temperature observation of the correlation between atomic and electronic structure of graphene on Cu(110).
    (2016) Silva, Thais Chagas Peixoto; Cunha, Thiago Henrique Rodrigues da; Matos, Matheus Josué de Souza; Reis, Diogo Duarte dos; Araujo, Karolline Aparecida de Souza; Malachias, Angelo; Mazzoni, Mario Sergio de Carvalho; Ferlauto, Andre Santarosa; Paniago, Rogério Magalhães
    In this work we have used atomically-resolved scanning tunneling microscopy and spectroscopy to study the interplay between the atomic and electronic structure of graphene formed on copper via chemical vapor deposition. Scanning tunneling microscopy directly revealed the epitaxial match between a single layer of graphene and the underlying copper substrate in different crystallographic orientations. Using scanning tunneling spectroscopy we have directly measured the electronic density of states of graphene layers near the Fermi level, observing the appearance of a series of peaks in specific cases. These features were analyzed in terms of substrate-induced perturbations in the structural and electronic properties of graphene by means of atomistic models supported by density functional theory calculations.