Graphene: Evidence for a New Two‐Dimensional C<sub>4</sub>H‐Type Polymer Based on Hydrogenated Graphene (Adv. Mater. 39/2011)

Haberer, Danny; Giusca, Cristina E.; Wang, Ying; Sachdev, Hermann; Fedorov, Alexander; Farjam, Mani; Jafari, Saman; Vyalikh, D. V.; Usachov, Dmitry Yu.; Liu, Xianjie; Treske, Uwe; Grobosch, M.; Vilkov, O. Yu.; Adamchuk, V. K.; Irle, Stephan; Silva, S. Ravi P.; Knupfer, M.; Büchner, B.; Grüneis, A.

doi:10.1002/adma.201190157

Cited by 2 publications

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“…At zero doping the C 8 X 2 structures are by several 100 meV per atom more favorable than the X[1:1] or X[1:0] structures. This finding is in line with the tendency of H and F to aggregate when adsorbed on graphene 2,23,24 .…”

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confidence: 87%

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Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

et al. 2014

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We show that charge doping can induce transitions between three distinct adsorbate phases in hydrogenated and fluorinated graphene. By combining ab initio, approximate density functional theory and tight binding calculations we identify a transition from islands of C 8 H 2 and C 8 F 2 to random adsorbate distributions around a doping level of ±0.05 e/Catom. Furthermore, in situations with random adsorbate coverage, charge doping is shown to trigger an ordering transition where the sublattice symmetry is spontaneously broken when the doping level exceeds the adsorbate concentration. Rehybridization and lattice distortion energies make graphene which is covalently functionalized from one side only most susceptible to these two kinds of phase transitions. The energy gains associated with the clustering and ordering transitions exceed room temperature thermal energies.

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confidence: 87%

“…Previous DFT calculations showed that the C 8 X 2 -structures (Fig. 1C shaded area) correspond to the upper concentration limit for H/F single side adsorption on graphene 2,23 . We thus compare E ads for the ordered C 8 X 2 structures to graphene with 10% adsorbed hydrogen and fluorine adatoms 1 in fully random (X[1:1], Fig.…”

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confidence: 71%

Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

et al. 2014

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“…Large adatoms prefer the hollow site position when added to a graphene sheet [7] while small atoms such as hydrogen prefer the top site position [5]. Therefore, implicit assumption of s-wave orbital structure for the impurity atom itself is only feasible for top site positions.…”

Section: Internal Structure Of the Impurity Orbital In Hollow Site Ad...mentioning

confidence: 99%

“…For example, two-dimensionality allows for tuning the carrier type and density by a gate voltage. On the one hand, the flat structure of graphene allows us to add/substitute various atoms on graphene [5]. On the other hand, the two-dimensional structure further allows us to conveniently remove some of the carbon atoms and create vacancies.…”

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confidence: 99%

Stable local moments of vacancies, substitutional and hollow site impurities in graphene

Mashkoori

Jafari

2015

J. Phys.: Condens. Matter

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The two-sublattice nature of graphene lattice in conjunction with three-fold rotational symmetry, allows for the p-wave hybridization of the impurity state with the Bloch states of carbon atoms. Such an opportunity is not available in normal metals where the wave function is scalar. The p-wave hybridization function V(→k) appears when dealing with vacancies, substitutional adatoms and the hollow site impurities while the s-wave mixing on graphene lattice pertains only to the top site impurities. In this work, we compare the local moment formation in these two cases and find that the local moments formed by p-wave mixing compared to the s-wave one are robust against the changes in the parameters of the model. Furthermore, we investigate the stability of the local moments in the above cases. We find that the quantum fluctuations can destroy the local moments in the case of s-wave hybridization, while the local moments formed by p-wave hybridization survive the quantum fluctuations. Based on these findings, we propose vacancies, substitutional adatoms, and hollow site adatoms as possible candidates to produce stable local moments in graphene.

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Graphene: Evidence for a New Two‐Dimensional C₄H‐Type Polymer Based on Hydrogenated Graphene (Adv. Mater. 39/2011)

Cited by 2 publications

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Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

Stable local moments of vacancies, substitutional and hollow site impurities in graphene

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Graphene: Evidence for a New Two‐Dimensional C4H‐Type Polymer Based on Hydrogenated Graphene (Adv. Mater. 39/2011)

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Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

Charge-doping-induced phase transitions in hydrogenated and fluorinated graphene

Stable local moments of vacancies, substitutional and hollow site impurities in graphene

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Graphene: Evidence for a New Two‐Dimensional C₄H‐Type Polymer Based on Hydrogenated Graphene (Adv. Mater. 39/2011)