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  1. Article ; Online: On the mechanical properties and fracture patterns of the nonbenzenoid carbon allotrope (biphenylene network): a reactive molecular dynamics study.

    Pereira, M L / da Cunha, W F / de Sousa, R T / Amvame Nze, G D / Galvão, D S / Ribeiro, L A

    Nanoscale

    2022  Volume 14, Issue 8, Page(s) 3200–3211

    Abstract: Recently, a new two-dimensional carbon allotrope named biphenylene network (BPN) was experimentally realized. The BPN structure consists of four-, six-, and eight-membered rings of ... ...

    Abstract Recently, a new two-dimensional carbon allotrope named biphenylene network (BPN) was experimentally realized. The BPN structure consists of four-, six-, and eight-membered rings of sp
    Language English
    Publishing date 2022-02-24
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/d1nr07959j
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Dynamics and structural transformations of carbon onion-like structures under high-velocity impacts

    Pereira Júnior, M.L. / da Cunha, W.F. / de Sousa Junior, R.T. / Amvame Nze, G.D. / Galvão, D.S. / Ribeiro Júnior, L.A.

    Carbon. 2022 Apr. 15, v. 189

    2022  

    Abstract: Carbon nano-onions (CNO) are multilayered fullerenes. They exhibit good electrical conductivity and large surface area, being of interest for several optoelectronic applications. However, it is still an open question what synthesis routes can be used to ... ...

    Abstract Carbon nano-onions (CNO) are multilayered fullerenes. They exhibit good electrical conductivity and large surface area, being of interest for several optoelectronic applications. However, it is still an open question what synthesis routes can be used to convert them into diamonds. Here, we used fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the dynamics and structural transformations of CNO structures under high-velocity impacts against a fixed and rigid substrate. The aim of this study is to propose a new synthesis route, based on the mechanical impact of CNO, that can be exploited in the conversion of onions to diamonds. Our results indicated three regimes formed after the CNO impact: slightly deformed CNO (quasi-elastic collision, below 2.0 km/s), collapsed CNO (inelastic collisions, between 3.0 and 5.0 km/s) forming a diamondoid-like core, and fragmented CNO yielding linear atomic carbon chains (above 5.0 km/s). We also discussed the dynamical reconfiguration of carbon-carbon bonds during the collision process. The impact of CNO yielded sp³-like bond types for all the used initial velocities. At intermediate velocities (between 3.0 and 5.0 km/s), the inelastic collision forms diamondoid-like cores by converting a substantial quantity of sp²-like bonds into sp³-like ones.
    Keywords electrical conductivity ; fullerene ; molecular dynamics ; surface area
    Language English
    Dates of publication 2022-0415
    Size p. 422-429.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 0008-6223
    DOI 10.1016/j.carbon.2021.12.064
    Database NAL-Catalogue (AGRICOLA)

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  3. Book ; Online: Irida-Graphene

    Junior, M. L. Pereira / da Cunha, W. F. / Giozza, W. F. / Junior, R. T. de Sousa / Junior, L. A. Ribeiro

    A New 2D Carbon Allotrope

    2022  

    Abstract: Several 2D carbon-based materials have been computationally designed in the last years due to the success achieved by graphene. Here, we propose a new 2D all-sp$^2$ carbon allotrope, named Irida-Graphene (IG), using a bottom-up approach. IG is composed ... ...

    Abstract Several 2D carbon-based materials have been computationally designed in the last years due to the success achieved by graphene. Here, we propose a new 2D all-sp$^2$ carbon allotrope, named Irida-Graphene (IG), using a bottom-up approach. IG is composed of fused rings containing 3-6-8 carbon atoms. We employed density functional theory calculations and reactive (ReaxFF) molecular dynamics simulations to examine its mechanical, structural, electronic, and optical properties. Results showed that IG exhibits good dynamical and thermal stabilities. Its estimated elastic modulus varies between 80-113 GPa. IG is a metallic material and presents a Dirac cone above the Fermi level in the center of the band. The intense optical activity of IG is restricted to the infrared and violet regions. IG can act as a violet collector for photon energies of about 3.0 eV since it presents very low reflectivity and refractive index greater than one.

    Comment: 11 pages and 07 figures
    Keywords Condensed Matter - Materials Science ; Condensed Matter - Mesoscale and Nanoscale Physics ; 00-xx ; J.2 ; I.6
    Subject code 541
    Publishing date 2022-08-18
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Dynamics and Structural Transformations of Carbon Onion-Like under High-Velocity Impacts

    Júnior, M. L. Pereira / da Cunha, W. F. / Júnior, R. T. de Sousa / Nzeb, G. D. Amvame / Galvão, D. S. / Júnior, L. A. Ribeiro

    2021  

    Abstract: Carbon nano-onions (CNO) are multi-shell fullerenes. In the present work, we used fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the dynamics and structural transformations of CNO structures under high-velocity impacts against ... ...

    Abstract Carbon nano-onions (CNO) are multi-shell fullerenes. In the present work, we used fully atomistic reactive (ReaxFF) molecular dynamics simulations to study the dynamics and structural transformations of CNO structures under high-velocity impacts against a fixed and rigid substrate. We considered single and multi-shell CNO (up to six shells) and at different impact velocities (from 2 up to 7 Km/s). Our results indicated three regimes formed after the CNO impact: slightly deformed CNO (quasi-elastic collision, below 2.0 Km/s), collapsed CNO (inelastic collisions, between 3.0 and 5.0 Km/s) forming a diamondoid-like core, and fragmented CNO yielding linear atomic carbon chains (above 5.0 Km/s). We also discussed the dynamical reconfiguration of carbon-carbon bonds during the collision process. The impact of CNO against the substrate yielded $sp^3$-like bond types for all the used initial velocities. At intermediate velocities (between 3.0 and 5.0 Km/s), the inelastic collision forms diamondoid-like cores by converting a substantial quantity of $sp^2$ bonds into $sp^3$ ones. In the high velocities regime, the total number of $sp^1$, $sp^2$, and $sp^3$ bonds tend to be similar.

    Comment: 18 pages and 07 figures
    Keywords Condensed Matter - Materials Science ; 00-xx ; J.2 ; I.6
    Subject code 541
    Publishing date 2021-09-14
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Book ; Online: On the Thermomechanical Properties and Fracture Patterns of the Novel Nonbenzenoid Carbon Allotrope (Biphenylene Network)

    Júnior, M. L. Pereira / da Cunha, W. F. / Junior, R. T. de Sousa / Nze, G. D. Amvame / Galvão, D. S. / Júnior, L. A. Ribeiro

    A Reactive Molecular Dynamics Study

    2021  

    Abstract: Recently, a new two-dimensional carbon allotrope, named biphenylene network (BPN) was experimentally realized. The BPN structure is composed of four-, six-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this work, we carried out fully- ... ...

    Abstract Recently, a new two-dimensional carbon allotrope, named biphenylene network (BPN) was experimentally realized. The BPN structure is composed of four-, six-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the thermomechanical properties and fracture patterns of non-defective and defective (nanocracks) BPN. Our results show that under uniaxial tensile loading, BPN is converted into four distinct morphologies before fracture starts. This conversion process is dependent on the stretching direction. Some of the formed structures are mainly formed by eight-membered rings, which have different shapes in each morphology. In one of them, a graphitization process was observed before the complete fracture. Importantly, in the presence of nanocracks, no new morphologies are formed. BPN exhibits a distinct fracture process when contrasted to graphene. After the critical strain threshold, the graphene transitions from an elastic to a brittle regime, while BPN can exhibit different inelastic stages. These stages are associated with the appearance of new morphologies. However, BPN shares some of the exceptional graphene properties. Its calculated Young's modulus and melting point values are comparable to the graphene ones, about 1019.4 GPa and 4024K, respectively.

    Comment: 12 pages and 09 figures
    Keywords Condensed Matter - Materials Science ; 00-xx ; J.2 ; I.6
    Subject code 541
    Publishing date 2021-09-23
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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  6. Article ; Online: Investigation of the Abstraction and Dissociation Mechanism in the Nitrogen Trifluoride Channels: Combined Post-Hartree-Fock and Transition State Theory Approaches.

    Claudino, D / Gargano, R / Carvalho-Silva, Valter H / E Silva, Geraldo M / da Cunha, W F

    The journal of physical chemistry. A

    2016  Volume 120, Issue 28, Page(s) 5464–5473

    Abstract: The present paper concludes our series of kinetics studies on the reactions involved in the complex mechanism of nitrogen trifluoride decomposition. Two other related reactions that, along with this mechanism, take part in an efficient boron nitride ... ...

    Abstract The present paper concludes our series of kinetics studies on the reactions involved in the complex mechanism of nitrogen trifluoride decomposition. Two other related reactions that, along with this mechanism, take part in an efficient boron nitride growth process are also investigated. We report results concerning two abstraction reactions, namely NF2 + N ⇄ 2NF and NF3 + NF ⇄ 2NF2, and two dissociations, N2F4 ⇄ 2NF2 and N2F3 ⇄ NF2 + NF. State-of-the-art electronic structure calculations at the CCSD(T)/cc-pVTZ level of theory were considered to determine geometries and frequencies of reactants, products, and transition states. Extrapolation of the energies to the complete basis set limit was used to obtain energies of all the species. We applied transition state theory to compute thermal rate constants including Wigner, Eckart, Bell, and deformed theory corrections in order to take tunneling effects into account. The obtained results are in good agreement with the experimental data available in the literature and are expected to provide a better phenomenological understanding of the NF3 decomposition role in the boron nitride growth for a wide range of temperature values.
    Language English
    Publishing date 2016-07-21
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/acs.jpca.6b04947
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Electron-Lattice Coupling in Armchair Graphene Nanoribbons.

    de Oliveira Neto, P H / Teixeira, J F / da Cunha, W F / Gargano, R / E Silva, G M

    The journal of physical chemistry letters

    2012  Volume 3, Issue 20, Page(s) 3039–3042

    Abstract: We report the effects of electron-lattice coupling on the charge density distribution study of armchair graphene nanoribbons (GNRs). Here, we perform a theoretical investigation explaining the unexpected electronic density states observed experimentally. ...

    Abstract We report the effects of electron-lattice coupling on the charge density distribution study of armchair graphene nanoribbons (GNRs). Here, we perform a theoretical investigation explaining the unexpected electronic density states observed experimentally. By means of a tight-binding approach with electron-lattice coupling, we obtained the same characteristic pattern of charge density along the C-C bonds suggested by both scanning tunneling and transmission electron microscopic measurements. Our results suggest electronic localized states whose sizes are dependent on the GNR width. We also show that our model rescues the quasi-particle charge-transport mechanism in GNRs. The remarkable agreement with experimental evidence allows us to conclude that our model could be, in many aspects, a fundamental tool when it comes to the phenomenological understanding of the charge behavior in this kind of system.
    Language English
    Publishing date 2012-10-18
    Publishing country United States
    Document type Journal Article
    ISSN 1948-7185
    ISSN 1948-7185
    DOI 10.1021/jz301247u
    Database MEDical Literature Analysis and Retrieval System OnLINE

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