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The NGA and the commercialization of graphene - InvestorIntel

Google News - Graphene - 1 hour 9 min ago

InvestorIntel

The NGA and the commercialization of graphene
InvestorIntel
Dr Zina Cinker is doing something rather interesting in the world of graphene. She is the Executive Director of the National Graphene Association (NGA) based in Nashville, TN, USA. Read on to find out why this is important…

Phosphorene-directed self-assembly of asymmetric PS- b -PMMA block copolymer for perpendicularly-oriented sub-10 nm PS nanopore arrays

Publications on 2D Materials - 3 hours 26 min ago

Few-layer black phosphorus, also known as phosphorene, is a new two-dimensional material which is of enormous interest for applications, mainly in electronics and optoelectronics. Herein, we for the first time employ phosphorene for directing the self-assembly of asymmetric polystyrene- block -polymethylmethacrylate (PS- b -PMMA) block copolymer (BCP) thin film to form the perpendicular orientation of sub-10 nm PS nanopore arrays in a hexagonal fashion normal to the interface. We experimentally demonstrate that none of the PS and PMMA blocks exhibit preferential affinity to the phosphorene-modified surface. Furthermore, the perpendicularly-oriented PS nanostructures almost stay unchanged with the variation of number of layers of few-layer phosphorene nanoflakes between 15–30 layers. Differing from the neutral polymer brushes which are widely used for chemical modification of the silicon substrate, phosphorene provides a novel physical way to control the interfacial int…

Published in: "Nanotechnology".

The post Phosphorene-directed self-assembly of asymmetric PS- b -PMMA block copolymer for
perpendicularly-oriented sub-10 nm PS nanopore arrays
appeared first on 2D Research.

Optical Forging of Graphene into Three-Dimensional Shapes

Publications on 2D Materials - 5 hours 22 min ago

Nano LettersDOI: 10.1021/acs.nanolett.7b03530

Published in: "Nano Letters".

The post Optical Forging of Graphene into Three-Dimensional
Shapes
appeared first on 2D Research.

Noncovalent functionalization and charge transfer in antimonene

Publications on 2D Materials - 5 hours 31 min ago

Antimonene, a novel group-15 2D material, is functionalized with a tailor-made perylene bisimide through strong van-der-Waals interactions. The functionalization process leads to a dramatic quenching of the perylene fluorescence, which surpasses that observed for graphene or black phosphorus, allowing a straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, pointing towards the spontaneous formation of a sub-nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge transfer band gap of 1.1 eV.

Published in: "Angewandte Chemie International Edition".

The post Noncovalent functionalization and charge transfer in antimonene appeared first on 2D Research.

Inducing 3-component fermions in centrosymmetric system by breaking TRS. (arXiv:1709.07763v1 [cond-mat.mtrl-sci])

Publications on 2D Materials - 5 hours 58 min ago

Recent researches show that by breaking inversion symmetry Dirac fermions can split into new fermions with 3-component. In this article, we demonstrate that Dirac fermions can also split into 3-component fermions with time reversal symmetry (TRS) breaking while inversion symmetry is preserved. Firstly, we conduct a symmetry analysis with the commutation relations among all symmetry operators of a Dirac semimetal and find out the symmetry conditions of Dirac fermions splitting into 3-component fermions. With the symmetry conditions, we derive the $kcdot P$ effective Hamiltonian of TRS breaking and compare it with the Hamiltonian of inversion symmetry breaking. We find that they are different in $Gamma$ point eigenenergies. This can be considered as consequence of Kramers degeneracy breaking which is a clear signature of TRS breaking. Moreover, with the $kcdot P$ effective Hamiltonian of the system we show that TRS-breaking-induced 3-component fermions can split into Weyl fermions while a small magnetic field is applied. At the end, we show our first principles calculation results are consistent with the symmetry analysis and the $kcdot P$ predictions. Our work clarifies the similarities and the differences between TRS-breaking-induced 3-component fermions and inversion-symmetry-breaking-induced 3-component fermions and extends the scope of 3-component fermion behaviors.

Published in: "arXiv Material Science".

The post Inducing 3-component fermions in centrosymmetric system by breaking TRS. (arXiv:1709.07763v1 [cond-mat.mtrl-sci]) appeared first on 2D Research.

Tin-selenium compounds at ambient and high pressures. (arXiv:1709.07570v1 [cond-mat.mtrl-sci])

Publications on 2D Materials - 5 hours 58 min ago

SnxSey crystalline compounds consisting of Sn and Se atoms of varying composition are systematically investigated at pressures from 0 to 100 GPa using the first-principles evolutionary crystal structure search method based on density functional theory (DFT). All known experimental phases of SnSe and SnSe2 are found without any prior input. A second order polymorphic phase transition from SnSe-Pnma phase to SnSe-Cmcm phase is predicted at 2.5 GPa. Initially being semiconducting, this phase becomes metallic at 7.3 GPa. Upon further increase of pressure up to 36.6 GPa, SnSe-Cmcm phase is transformed to CsCl-type SnSe-Pm3m phase, which remains stable at even higher pressures. A metallic compound with different stoichiometry, Sn3Se4-I43d, is found to be thermodynamically stable from 18 GPa to 70 GPa. Known semiconductor tin diselenide SnSe2-P3m1 phase is found to be thermodynamically stable from ambient pressure up to 18 GPa. Initially being semiconducting, it experiences metalization at pressures above 8 GPa.

Published in: "arXiv Material Science".

The post Tin-selenium compounds at ambient and high pressures. (arXiv:1709.07570v1 [cond-mat.mtrl-sci]) appeared first on 2D Research.

Inter-electron interactions and the RKKY potential between H adatoms in graphene. (arXiv:1703.05743v2 [cond-mat.str-el] UPDATED)

Publications on 2D Materials - 5 hours 58 min ago

We use first-principles Quantum Monte-Carlo simulations to study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between hydrogen adatoms attached to a graphene sheet. We find that the pairwise RKKY interactions at distances of a few lattice spacings are strongly affected by inter-electron interactions, in particular, the potential barrier between widely separated adatoms and the dimer configuration becomes wider and thus harder to penetrate. We also point out that anti-ferrromagnetic and charge density wave orderings have very different effects on the RKKY interaction. Finally, we analyze the stability of several regular adatom superlattices with respect to small displacements of a single adatom, distinguishing the cases of adatoms which populate either both or only one sublattice of the graphene lattice.

Published : "arXiv Mesoscale and Nanoscale Physics".

The post Inter-electron interactions and the RKKY potential between H adatoms in graphene. (arXiv:1703.05743v2 [cond-mat.str-el] UPDATED) appeared first on 2D Research.

Controlling the layer localization of gapless states in bilayer graphene with a gate voltage. (arXiv:1709.07624v1 [cond-mat.mes-hall])

Publications on 2D Materials - 5 hours 58 min ago

Experiments in gated bilayer graphene with stacking domain walls present topological gapless states protected by no-valley mixing. Here we research these states under gate voltages using atomistic models, which allow us to elucidate their origin. We find that the gate potential controls the layer localization of the two states, which switches non-trivially between layers depending on the applied gate voltage magnitude. We also show how these bilayer gapless states arise from bands of single-layer graphene by analyzing the formation of carbon bonds between layers. Based on this analysis we provide a model Hamiltonian with analytical solutions, which explains the layer localization as a function of the ratio between the applied potential and interlayer hopping. Our results open a route for the manipulation of gapless states in electronic devices, analogous to the proposed writing and reading memories in topological insulators.

Published : "arXiv Mesoscale and Nanoscale Physics".

The post Controlling the layer localization of gapless states in bilayer graphene with a gate voltage. (arXiv:1709.07624v1 [cond-mat.mes-hall]) appeared first on 2D Research.

Electronic Structure Theory of Strained Two-Dimensional Materials. (arXiv:1709.07510v1 [cond-mat.mes-hall])

Publications on 2D Materials - 5 hours 58 min ago

We derive electronic tight-binding Hamiltonians for strained graphene, hexagonal boron nitride and transition metal dichalcogenides based on Wannier transformation of {it ab initio} density functional theory calculations. Our microscopic models include strain effects to leading order that respect the crystal symmetry and local crystal configuration, and are beyond the central force approximation which assumes only pair-wise distance dependence. Based on these models, we also derive and analyze the effective low-energy k $cdot$ p Hamiltonians. Our {it ab initio} approaches complement the symmetry group representation construction for such effective low-energy Hamiltonians and provide the values of the coefficients for each symmetry-allowed term. These models are relevant for the design of electronic device applications, since they provide the framework for describing the coupling of electrons to other degrees of freedom including phonons, spin and the electromagnetic field. The models can also serve as the basis for exploring the physics of many-body systems of interesting quantum phases.

Published : "arXiv Mesoscale and Nanoscale Physics".

The post Electronic Structure Theory of Strained Two-Dimensional Materials. (arXiv:1709.07510v1 [cond-mat.mes-hall]) appeared first on 2D Research.

Asymmetric Electron-Hole Decoherence in Ion-Gated Epitaxial Graphene. (arXiv:1709.07549v1 [cond-mat.mes-hall])

Publications on 2D Materials - 5 hours 58 min ago

We report on asymmetric electron-hole decoherence in epitaxial graphene gated by an ionic liquid. The observed negative magnetoresistance near zero magnetic field for different gate voltages, analyzed in the framework of weak localization, gives rise to distinct electron-hole decoherence. The hole decoherence rate increases prominently with decreasing negative gate voltage while the electron decoherence rate does not exhibit any substantial gate dependence. Quantitatively, the hole decoherence rate is as large as the electron decoherence rate by a factor of two. We discuss possible microscopic origins including spin-exchange scattering consistent with our experimental observations.

Published : "arXiv Mesoscale and Nanoscale Physics".

The post Asymmetric Electron-Hole Decoherence in Ion-Gated Epitaxial Graphene. (arXiv:1709.07549v1 [cond-mat.mes-hall]) appeared first on 2D Research.

Normal and skewed phosphorene nanoribbons in combined magnetic and electric fields

Publications on 2D Materials - 7 hours 23 min ago

Author(s): Vladimir V. Arsoski, Marko M. Grujić, Nemanja A. Čukarić, Milan Ž. Tadić, and François M. PeetersThe energy spectrum and eigenstates of single-layer black phosphorus nanoribbons in the presence of a perpendicular magnetic field and an in-plane transverse electric field are investigated by means of a tight-binding method, and the effect of different types of edges is examined analytically. A des…[Phys. Rev. B 96, 125434] Published Mon Sep 25, 2017

Published in: "Physical Review B".

The post Normal and skewed phosphorene nanoribbons in combined magnetic and electric fields appeared first on 2D Research.

Weak measurement of quantum superposition states in graphene

Publications on 2D Materials - 7 hours 23 min ago

Author(s): Maxim Trushin, Johannes Bülte, and Wolfgang BelzigWe employ a weak measurement approach to demonstrate the very existence of the photoexcited interband superposition states in intrinsic graphene. We propose an optical two-beam setup where such measurements are possible and derive an explicit formula for the differential optical absorption that cont…[Phys. Rev. B 96, 125146] Published Mon Sep 25, 2017

Published in: "Physical Review B".

The post Weak measurement of quantum superposition states in graphene appeared first on 2D Research.

Highly Efficient Rubrene–Graphene Charge-Transfer Interfaces as Phototransistors in the Visible Regime

Publications on 2D Materials - 9 hours 23 min ago

Abstract Atomically thin materials such as graphene are uniquely responsive to charge transfer from adjacent materials, making them ideal charge-transport layers in phototransistor devices. Effective implementation of organic semiconductors as a photoactive layer would open up a multitude of applications in biomimetic circuitry and ultra-broadband imaging but polycrystalline and amorphous thin films have shown inferior performance compared to inorganic semiconductors. Here, the long-range order in rubrene single crystals is utilized to engineer organic-semiconductor–graphene phototransistors surpassing previously reported photogating efficiencies by one order of magnitude. Phototransistors based upon these interfaces are spectrally selective to visible wavelengths and, through photoconductive gain mechanisms, achieve responsivity as large as 107 A W−1 and a detectivity of 9 × 1011 Jones at room temperature. These findings point toward implementing low-cost, flexible materials for amplified imaging at ultralow light levels. Responsivity, detectivity, and photogating quantum efficiency as high as 107 A W−1, 9 × 1011 Jones, and 1% are achieved in an entirely organic graphene-based phototransistor by employing a rubrene single crystal as the photoactive layer. Long-range diffusion of triplet excitons in rubrene overcomes conflicting requirements for efficient light absorption and charge extraction, pointing toward amplified imaging of ultraweak light signals in biocompatible sensors.

Published in: "Advanced Materials".

The post Highly Efficient Rubrene–Graphene Charge-Transfer Interfaces as Phototransistors in the Visible Regime appeared first on 2D Research.

Graphene water filter commercialisation speeds up in UK - WaterWorld

Google News - Graphene - Mon, 25/09/2017 - 11:59pm

WaterWorld

Graphene water filter commercialisation speeds up in UK
WaterWorld
LONDON, England – UK company G2O Water Technologies has signed an agreement with an unnamed consumer products company to test and evaluate its graphene-based water treatment filtration technology. G2O's technology works by creating low-cost ...

Global Graphene Market Will Reach USD 193.68 Million by 2022: Zion Market Research - GlobeNewswire (press release)

Google News - Graphene - Mon, 25/09/2017 - 9:19pm

Global Graphene Market Will Reach USD 193.68 Million by 2022: Zion Market Research
GlobeNewswire (press release)
Graphene is a substance that contains high electronic mobility, heat resistance, and permeability. It is a good conductor of electricity and heat. This quality of graphene surging the use of its uses in consumer electronics, conductive inks, composites ...

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