Mechanical Properties and Fracture Dynamics of Silicene Membranes

As graphene became one of the most important materials today, there is a renewed interest on others similar structures. One example is silicene, the silicon analogue of graphene. It share some the remarkable graphene properties, such as the Dirac cone, but presents some distinct ones, such as a pronounced structural buckling. We have investigated, through density functional based tight-binding (DFTB), as well as reactive molecular dynamics (using ReaxFF), the mechanical properties of suspended single-layer silicene. We calculated the elastic constants, analyzed the fracture patterns and edge reconstructions. We also addressed the stress distributions, unbuckling mechanisms and the fracture dependence on the temperature. We analysed the differences due to distinct edge morphologies, namely zigzag and armchair

Dynamical Aspects Of The Unzipping Of Multiwalled Boron Nitride Nanotubes.

Boron nitride nanoribbons (BNNRs) exhibit very interesting magnetic properties, which could be very useful in the development of spintronic based devices. One possible route to obtain BNNRs is through the unzipping of boron nitride nanotubes (BNNTs), which have been already experimentally realized. In this work, different aspects of the unzipping process of BNNTs were investigated through fully atomistic molecular dynamics simulations using a classical reactive force field (ReaxFF). We investigated multiwalled BNNTs of different diameters and chiralities. Our results show that chirality plays a very important role in the unzipping process, as well as the interlayer coupling. These combined aspects significantly change the fracturing patterns and several other features of the unzipping processes in comparison to the ones observed for carbon nanotubes. Also, similar to carbon nanotubes, defective BNNTs can create regions of very high curvature which can act as a path to the unzipping process.1519147-5

Functionalized carbophenes as high-capacity versatile gas adsorbents: An ab initio study

This study employs density functional theory (DFT) and density functional tight-binding theory (DFTB) to determine the adsorption properties of carbon dioxide (CO$_2$), methane (CH$_4$), and dihydrogen (H$_2$) in carbophenes functionalized with carboxyl (COOH), amine (NH$_2$), nitro (NO$_2$), and hydroxyl (OH) groups. We demonstrate that carbophenes are promising candidates as adsorbents for these gasses. Carbophenes have larger CO$_2$ and CH$_4$ adsorption energies than other next-generation solid-state capture materials. Yet, the low predicted desorption temperatures mean they can be beneficial as air scrubbers in confined spaces. Functionalized carbophenes have H$_2$ adsorption energies usually observed in metal-containing materials. Further, the predicted desorption temperatures of H$_2$ from carbophenes lie within the DOE Technical Targets for Onboard Hydrogen Storage for Light-Duty Vehicles (DOEHST) operating temperature range. The possibility of tailoring the degree of functionalization in combination with selecting sufficiently open carbophene structures that allow for multiple strong interactions without steric hindrance (crowding) effects, added to the multiplicity of possible functional groups alone or in combination, suggests that these very light materials can be ideal adsorbates for many gases. Tailoring the design to specific adsorption or separation needs would require extensive combinatorial investigations

Melting of Partially Fluorinated Graphene: From Detachment of Fluorine Atoms to Large Defects and Random Coils

The melting of fluorographene is very unusual and depends strongly on the degree of fluorination. For temperatures below 1000 K, fully fluorinated graphene (FFG) is thermo-mechanically more stable than graphene but at T$_m\approx$2800 K FFG transits to random coils which is almost twice lower than the melting temperature of graphene, i.e. 5300 K. For fluorinated graphene (PFG) up to 30 % ripples causes detachment of individual F-atoms around 2000 K while for 40-60 % fluorination, large defects are formed beyond 1500 K and beyond 60% of fluorination F-atoms remain bonded to graphene until melting. The results agree with recent experiments on the dependence of the reversibility of the fluorination process on the percentage of fluorination.Comment: 16 pages, 6 figure

Melting of Partially Fluorinated Graphene: From Detachment of Fluorine Atoms to Large Defects and Random Coils

The melting of fluorographene is very unusual and depends strongly on the degree of fluorination. For temperatures below 1000 K, fully fluorinated graphene (FFG) is thermo-mechanically more stable than graphene but at T m ≈ 2800 K FFG transits to random coils which is almost twice lower than the melting temperature of graphene, i.e. 5300 K. For fluorinated graphene (PFG) up to 30% ripples causes detachment of individual F-atoms around 2000 K while for 40-60% fluorination, large defects are formed beyond 1500 K and beyond 60% of fluorination F-atoms remain bonded to graphene until melting. The results agree with recent experiments on the dependence of the reversibility of the fluorination process on the percentage of fluorination.Fil: Singh, Sandeep Kumar. Universiteit Antwerpen. Department of Physics; BélgicaFil: Costamagna, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Neek Amal, M.. Universiteit Antwerpen. Department of Physics; BélgicaFil: Peeters, F. M.. Universiteit Antwerpen. Department of Physics; Bélgic

Controlled Route To The Fabrication Of Carbon And Boron Nitride Nanoscrolls: A Molecular Dynamics Investigation

Carbon nanoscrolls (graphene layers rolled up into papyrus-like tubular structures) are nanostructures with unique and interesting characteristics that could be exploited to build several new nanodevices. However, an efficient and controlled synthesis of these structures was not achieved yet, making its large scale production a challenge to materials scientists. Also, the formation process and detailed mechanisms that occur during its synthesis are not completely known. In this work, using fully atomistic molecular dynamics simulations, we discuss a possible route to nanoscrolls made from graphene layers deposited over silicon oxide substrates containing chambers/pits. The scrolling mechanism is triggered by carbon nanotubes deposited on the layers. The process is completely general and can be used to produce scrolls from other lamellar materials, like boron nitride, for instance. © 2013 American Institute of Physics.1135Bacon, R., (1960) J. Appl. Phys., 31, p. 283. , 10.1063/1.1735559Ijima, S., (1991) Nature, 354, p. 56. , 10.1038/354056a0Coluci, V.R., Braga, S.F., Baughman, R.H., Galvao, D.S., (2007) Phys. Rev. B, 75, p. 125404. , 10.1103/PhysRevB.75.125404Shi, X., Cheng, Y., Pugno, N.M., Gao, H., (2010) Appl. Phys. Lett., 96, p. 053115. , 10.1063/1.3302284Viculis, M.L., MacK, J.J., Kaner, R.B., (2003) Science, 299, p. 1361. , 10.1126/science.1078842Shioyama, H., Akita, T., (2003) Carbon, 41, p. 179. , 10.1016/S0008-6223(02)00278-6Tomanek, D., (2002) Physica B, 323, p. 86. , 10.1016/S0921-4526(02)00989-4Braga, S.F., Coluci, V.R., Legoas, S.B., Giro, R., Galvao, D.S., Baughman, R.H., (2004) Nano Lett., 4, p. 881. , 10.1021/nl0497272Pan, H., Feng, Y., Lin, J., (2005) Phys. Rev. B, 72, p. 085415. , 10.1103/PhysRevB.72.085415Rurali, R., Coluci, V.R., Galvao, D.S., (2006) Phys. Rev. B, 74, p. 085414. , 10.1103/PhysRevB.74.085414Savoskin, V.M., Mochalin, V.N., Yaroshenki, A.P., Lazareva, N.I., Konstantinova, T.E., Barsukov, I.V., Prokofiev, I.O., (2007) Carbon, 45, p. 2797. , 10.1016/j.carbon.2007.09.031Xie, X., Ju, L., Feng, X., Sun, Y., Zhou, R., Liu, K., Fan, S., Jiang, K., (2009) Nano Lett., 9, p. 2565. , 10.1021/nl900677yZhang, Z., Li, T., (2010) Appl. Phys. Lett., 97, p. 081909. , 10.1063/1.3479050Chu, L., Xue, Q., Zhang, T., Ling, C., (2011) J. Phys. Chem. C, 115, p. 15217. , 10.1021/jp2030768Chen, X., Li, L., Sun, X., Kia, H.G., Peng, H., (2012) Nanotechnology, 23, p. 055603. , 10.1088/0957-4484/23/5/055603Perim, E., Galvão, D.S., (2009) Nanotechnology, 20, p. 335702. , 10.1088/0957-4484/20/33/335702Rubio, A., Corkill, J.L., Cohen, M.L., (1994) Phys. Rev. B, 49, p. 5081. , 10.1103/PhysRevB.49.5081Blasé, X., Rubio, A., Louie, S.G., Cohen, M.L., (1994) Europhys. Lett., 28, p. 335. , 10.1209/0295-5075/28/5/007Rappe, A.K., Casewit, C.J., Colwell, K.S., Goddard III, W.A., Skiff, W.M., (1992) J. Am. Chem. Soc., 114, p. 10024. , 10.1021/ja00051a040http://www.accelrys.com, materials studio is a suite of simulation programs available from Accelrys. Accelrys, Inc. 10188 Telesis Court, Suite 100, San Diego, CA, 9212, USABunch, J.S., (2008) Nano Lett., 8, p. 2458. , 10.1021/nl801457bhttp://dx.doi.org/10.1063/1.4790304Chen, X., Boulos, R.A., Dobson, J.F., Raston, C.L., (2013) Nanoscale, 5, p. 498. , 10.1039/c2nr33071

Controlled route to the fabrication of carbon and boron nitride nanoscrolls: A molecular dynamics investigation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Carbon nanoscrolls (graphene layers rolled up into papyrus-like tubular structures) are nanostructures with unique and interesting characteristics that could be exploited to build several new nanodevices. However, an efficient and controlled synthesis of these structures was not achieved yet, making its large scale production a challenge to materials scientists. Also, the formation process and detailed mechanisms that occur during its synthesis are not completely known. In this work, using fully atomistic molecular dynamics simulations, we discuss a possible route to nanoscrolls made from graphene layers deposited over silicon oxide substrates containing chambers/pits. The scrolling mechanism is triggered by carbon nanotubes deposited on the layers. The process is completely general and can be used to produce scrolls from other lamellar materials, like boron nitride, for instance. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4790304]1135Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The Hydrogenation Dynamics Of H-bn Sheets

Hexagonal boron nitride (h-BN), also known as white graphite, is the inorganic analogue of graphite. Single layers of both structures have been already experimentally realized. In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of hydrogenation of h-BN single-layers membranes. Our results show that the rate of hydrogenation atoms bonded to the membrane is highly dependent on the temperature and that only at low temperatures there is a preferential bond to boron atoms. Unlike graphanes (hydrogenated graphene), hydrogenated h-BN membranes do not exhibit the formation of correlated domains. Also, the out-of-plane deformations are more pronounced in comparison with the graphene case. After a critical number of incorporated hydrogen atoms the membrane become increasingly defective, lost its two-dimensional character and collapses. The hydrogen radial pair distribution and second-nearest neighbor correlations were also analyzed. © 2013 Materials Research Society.15499198Novoselov, K.S., (2004) Science, 306, p. 666Cheng, S.H., (2010) Phys. Rev. B, 81, p. 205435Withers, F., Duboist, M., Savchenko, A.K., (2010) Phys. Rev. B, 82, p. 073403Sofo, J.O., Chaudari, A.S., Barber, G.D., (2007) Phys. Rev. B, 75, p. 153401Elias, D.C., (2009) Science, 323, p. 610Flores, M.Z.S., Autreto, P.A.S., Legoas, S.B., Galvao, D.S., (2009) Nanotechnology, 20, p. 465704Nair, R.R., (2010) Small, 6, p. 2773Paupitz, R., Autreto, P.A.S., Legoas, S.B., Srinivasan, S.G., Van Duin, A.C.T., Galvao, D.S., (2013) Nanotechnology, 24, p. 035706Jin, C., Lin, F., Suenaga, K., Lijima, S., (2009) Phys. Rev. Lett., 102, p. 19Meyer, J.C., Chuvulin, A., Algara-Siller, G., Biskupek, J., Kaiser, U., (2009) Nano Lett., 9, p. 2683Song, L., (2010) Nano Lett., 10, p. 5049Van Duin, A.C.T., Dasgupta, S., Lorant, F., Goddard III, W.A., (2001) J. Phys. Chem. A, 105, p. 9396Van Duin, A.C.T., Damste, J.S.S., (2003) Org. Geochem., 34, p. 515Han, S.S., Kang, J.K., Lee, H.M., Van Duin, A.C.T., Goddard III, W.A., (2005) J. Chem. Phys., 123, p. 114703Plimpton, S., (1995) J. Comp. Phys., 117, p. 1. , http://lammps.sandia.gov/Dos Santos, R.P.B., Perim, E., Autreto, P.A.S., Brunetto, G., Galvao, D.S., (2012) Nanotechnology, 23, p. 46570