| 1. |
- Faccio, Ricardo, et al.
(author)
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Electronic and Structural Distortions in Graphene Induced by Carbon Vacancies and Boron Doping
- 2010
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In: JOURNAL OF PHYSICAL CHEMISTRY C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 114:44, s. 18961-18971
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Journal article (peer-reviewed)abstract
- We present an ab initio-DFT/GGA-study on the structural and electronic distortions of modified graphene by the creation of vacancies, the inclusion of boron atoms, and the coexistence of both, by means of total energy and band structure calculations. In the case of coexistence of boron atoms and vacancy, the modified grapheme presents spin polarization only when B atoms locate far from vacancy. Thus, when a boron atom fills single and divacancies, it suppresses the spin polarization of the charge density. In particular, when B atoms fill a divacancy, a new type of rearrangement occurs, where a stable BC4 unit is formed inducing important out-of-plane distortions to graphene. All these findings suggest that new chemical modifications to grapheme and new types of vacancies can be used to modify its electronic properties.
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| 2. |
- Faccio, Ricardo, et al.
(author)
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Using density functional theory to increase the accuracy of experimental crystal structures : The case of potassium peroxocarbonate
- 2017
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In: Journal of Molecular Structure. - : Elsevier. - 0022-2860 .- 1872-8014. ; 1146, s. 1-4
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Journal article (peer-reviewed)abstract
- A first principles simulation of the crystal structure of potassium peroxocarbonate is presented, using density functional methods (both local and semilocal) for the calculations. An experimental crystal structure with a seemingly inconsistent disposition of the peroxide bonds was used as initial input. Both geometry optimizations of the molecular structure and optimization of the cell size were performed. While cell parameters and heavier atom positions determined at the GGA level are very close to the experimental ones, there are important discrepancies in the positioning of the hydrogen atoms. As a result of these calculations, it was shown that the assignment of the peroxydic hydrogens and the peroxydic bond in the experimental structure was incorrect. A more accurate structure is presented and geometrical as well as cell parameters described. It is also shown that LDA is not accurate enough to describe this type of ionic crystals, because of overbinding of the ions, leading to incorrect cell parameters and volume. Our methodology was validated using DFT methods with several basis sets. (C) 2017 Elsevier B.V. All rights reserved.
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| 3. |
- Pardo, Helena, et al.
(author)
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Raman characterization of bulk ferromagnetic nanostructured graphite
- 2012
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In: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 407:16, s. 3206-3209
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Journal article (peer-reviewed)abstract
- Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm(-1) showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.
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| 4. |
- Sangiovanni, Davide, et al.
(author)
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Correction: Discovering atomistic pathways for supply of metal atoms from methyl-based precursors to graphene surface (vol 25, pg 829, 2023)
- 2023
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In: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 25:7, s. 5887-5887
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Journal article (other academic/artistic)abstract
- Correction for Discovering atomistic pathways for supply of metal atoms from methyl-based precursors to graphene surface by Davide G. Sangiovanni et al., Phys. Chem. Chem. Phys., 2023, 25, 829-837, https://doi.org/10.1039/D2CP04091C.
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| 5. |
- Sangiovanni, Davide, et al.
(author)
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Discovering atomistic pathways for supply of metal atoms from methyl-based precursors to graphene surface
- 2022
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 25:1, s. 829-837
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Journal article (peer-reviewed)abstract
- Conceptual 2D group III nitrides and oxides (e.g., 2D InN and 2D InO) in heterostructures with graphene have been realized by metal-organic chemical vapor deposition (MOCVD). MOCVD is expected to bring forth the same impact in the advancement of 2D semiconductor materials as in the fabrication of established semiconductor materials and device heterostructures. MOCVD employs metal-organic precursors such as trimethyl-indium, -gallium, and -aluminum, with (strong) metal-carbon bonds. Mechanisms that regulate MOCVD processes at the atomic scale are largely unknown. Here, we employ density-functional molecular dynamics - accounting for van der Waals interactions - to identify the reaction pathways responsible for dissociation of the trimethylindium (TMIn) precursor in the gas phase as well as on top-layer and zero-layer graphene. The simulations reveal how collisions with hydrogen molecules, intramolecular or surface-mediated proton transfer, and direct TMIn/graphene reactions assist TMIn transformations, which ultimately enables delivery of In monomers or InH and CH3In admolecules, on graphene. This work provides knowledge for understanding the nucleation and intercalation mechanisms at the atomic scale and for carrying out epitaxial growth of 2D materials and graphene heterostructures.
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