1
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Jiang C, Li W, Liu Q. Impact of complex boundary on the hydrodynamic properties of methane nanofluidic flow via non-equilibrium multiscale molecular dynamics simulation. Sci Rep 2022; 12:11072. [PMID: 35773348 PMCID: PMC9246931 DOI: 10.1038/s41598-022-15323-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 06/22/2022] [Indexed: 11/09/2022] Open
Abstract
Understanding the impact of complex boundary on the hydrodynamic properties of methane nanofluidic is significant for production optimization and design of energy-saving emission reduction devices. In the molecule scale, however, the microscopic mechanisms of the influence of the complex boundary on the hydrodynamic characteristics are still not well understood. In this study, a mixture boundary Poiseuille flow model is proposed to study the hydrodynamic properties and explore the molecular mechanisms of confined methane nanofluidic using the Non-equilibrium multiscale molecular dynamics simulation (NEMSMD). In order to investigate the influences of nonslip and rough boundary on hydrodynamic behavior of nanofluidic by the present model in one simulation, the coordinate transformation methods regarding the local symmetry is showed. Simulation results show that the atom number density, velocity and temperature profiles present significant differences near the nonslip boundary and rough wall surface. Moreover, the slip length of methane nanofluidic near the rough boundary decreases with the increasing of the temperature. Furthermore, the viscosity values are calculated by parabolic fit of the local velocity data based on the present model, which demonstrates that the impact of the nonslip boundary on the shear viscosity compared with the experiment result is less than one obtained using the rough boundary. In addition, the local contours of rotational and translational energy are plotted, which show that the rotational and translational energies of nonslip boundary are obvious higher than those of rough boundary. These numerical results are very significant in understanding the impact of complex boundary conditions on hydrodynamic properties in nanofluidic theory and the design of nano-devices.
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Affiliation(s)
- Chuntao Jiang
- School of Mathematics and Statistics, Xinyang Normal University, Xinyang, 464000, China.
| | - Wuming Li
- School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, 454000, China
| | - Qingsheng Liu
- School of Mathematics and Statistics, Xinyang Normal University, Xinyang, 464000, China
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2
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Jiang C, Zhang Y. Direct matching between the flow factor approach model and molecular dynamics simulation for nanochannel flows. Sci Rep 2022; 12:396. [PMID: 35013479 PMCID: PMC8748866 DOI: 10.1038/s41598-021-04391-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 12/22/2021] [Indexed: 12/02/2022] Open
Abstract
Mathematically formulating nanochannel flows is challenging. Here, the values of the characteristic parameters were extracted from molecular dynamics simulation (MDS), and directly input to the closed-form explicit flow factor approach model (FFAM) for nanochannel flows. By this way, the physical nature of the simulated system in FFAM is the same with that in MDS. Two nano slit channel heights respectively with two different liquid-channel wall interactions were addressed. The flow velocity profiles across the channel height respectively calculated from MDS and FFAM were compared. By introducing the equivalent value \documentclass[12pt]{minimal}
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\begin{document}$${{\Delta_{im} } \mathord{\left/ {\vphantom {{\Delta_{im} } D}} \right. \kern-\nulldelimiterspace} D}$$\end{document}Δim/D, FFAM fairly agrees with MDS for all the cases. The study values FFAM in simulating nanochannel flows.
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Affiliation(s)
- Chuntao Jiang
- School of Mathematics and Statistics, Xinyang Normal University, Xinyang, Henan, China
| | - Yongbin Zhang
- College of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu, China.
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3
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Pham HD, Su WP, Nguyen TDH, Tran NTT, Lin MF. Rich p-type-doping phenomena in boron-substituted silicene systems. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200723. [PMID: 33489254 PMCID: PMC7813228 DOI: 10.1098/rsos.200723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
The essential properties of monolayer silicene greatly enriched by boron substitutions are thoroughly explored through first-principles calculations. Delicate analyses are conducted on the highly non-uniform Moire superlattices, atom-dominated band structures, charge density distributions and atom- and orbital-decomposed van Hove singularities. The hybridized 2p z -3p z and [2s, 2p x , 2p y ]-[3s, 3p x , 3p y ] bondings, with orthogonal relations, are obtained from the developed theoretical framework. The red-shifted Fermi level and the modified Dirac cones/π bands/σ bands are clearly identified under various concentrations and configurations of boron-guest atoms. Our results demonstrate that the charge transfer leads to the non-uniform chemical environment that creates diverse electronic properties.
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Affiliation(s)
- Hai Duong Pham
- Center of General Studies, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Wu-Pei Su
- Department of Physics, University of Houston, Houston, 77204 TX, USA
| | | | - Ngoc Thanh Thuy Tran
- Hierarchical Green-Energy Materials (Hi-GEM) Research Center, National Cheng Kung University, Tainan 70101, Taiwan
| | - Ming-Fa Lin
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
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4
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Liu HY, Lin SY, Wu JY. Stacking-configuration-enriched essential properties of bilayer graphenes and silicenes. J Chem Phys 2020; 153:154707. [PMID: 33092355 DOI: 10.1063/5.0024421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
First-principles calculations show that the geometric and electronic properties of silicene-related systems have diversified phenomena. Critical factors of group-IV monoelements, like buckled/planar structures, stacking configurations, layer numbers, and van der Waals interactions of bilayer composites, are considered simultaneously. The theoretical framework developed provides a concise physical and chemical picture. Delicate evaluations and analyses have been made on the optimal lattices, energy bands, and orbital-projected van Hove singularities. They provide decisive mechanisms, such as buckled/planar honeycomb lattices, multi-/single-orbital hybridizations, and significant/negligible spin-orbital couplings. We investigate the stacking-configuration-induced dramatic transformations of essential properties by relative shift in bilayer graphenes and silicenes. The lattice constant, interlayer distance, buckling height, and total energy essentially depend on the magnitude and direction of the relative shift: AA → AB → AA' → AA. Apparently, sliding bilayer systems are quite different between silicene and graphene in terms of geometric structures, electronic properties, orbital hybridizations, interlayer hopping integrals, and spin interactions.
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Affiliation(s)
- Hsin-Yi Liu
- Department of Physics/QTC/Hi-GEM, National Cheng Kung University, Tainan, Taiwan
| | - Shih-Yang Lin
- Department of Physics, National Chung Cheng University, Chiayi, Taiwan
| | - Jhao-Ying Wu
- Center of General Studies, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
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5
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De Padova P, Generosi A, Paci B, Ottaviani C, Quaresima C, Olivieri B, Kopciuszyński M, Żurawek L, Zdyb R, Krawiec M. New Findings on Multilayer Silicene on Si(111)√3×√3R30°-Ag Template. MATERIALS 2019; 12:ma12142258. [PMID: 31337057 PMCID: PMC6678445 DOI: 10.3390/ma12142258] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/08/2019] [Accepted: 07/11/2019] [Indexed: 11/16/2022]
Abstract
We report new findings on multilayer silicene grown on Si(111)√3 × √3 R30°-Ag template, after the recent first compelling experimental evidence of its synthesis. Low-energy electron diffraction, reflection high-energy electron diffraction, and energy-dispersive grazing incidence X-ray diffraction measurements were performed to show up the fingerprints of √3 × √3 multilayer silicene. Angle-resolved photoemission spectroscopy displayed new features in the second surface Brillouin zone, attributed to the multilayer silicene on Si(111)√3 × √3 R30°-Ag. Band-structure dispersion theoretical calculations performed on a model of three honeycomb stacked layers, silicene grown on Si(111)√3 × √3 R30°-Ag surface confirm the experimental results.
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Affiliation(s)
- Paola De Padova
- Consiglio Nazionale delle Ricerche-ISM, Via Fosso del Cavaliere 100, 00133 Roma, Italy.
- INFN-Laboratori Nazionali di Frascati Via Enrico Fermi 40, Frascati, 00044 Roma, Italy.
| | - Amanda Generosi
- Consiglio Nazionale delle Ricerche-ISM, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Barbara Paci
- Consiglio Nazionale delle Ricerche-ISM, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Carlo Ottaviani
- Consiglio Nazionale delle Ricerche-ISM, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Claudio Quaresima
- Consiglio Nazionale delle Ricerche-ISM, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Bruno Olivieri
- Consiglio Nazionale delle Ricerche-ISAC, Via Fosso del Cavaliere 100, 00133 Roma, Italy
| | - Marek Kopciuszyński
- Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin, Poland
| | - Lucyna Żurawek
- Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin, Poland
| | - Ryszard Zdyb
- Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin, Poland
| | - Mariusz Krawiec
- Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin, Poland.
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6
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Pandey D, Kamal C, Chakrabarti A. Intercalation of transition metals in aluminene bi-layers: An ab initio study. J Chem Phys 2019; 150:194702. [PMID: 31117777 DOI: 10.1063/1.5093945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using first principles calculations based on density functional theory (DFT), we probe various possible stacking arrangements of bilayer aluminene and intercalate six transition metal (TM) atoms (Ti, Cr, Mn, Fe, Co, and Ni) in unique bilayer aluminene systems. Further, we calculate valence charge density and electron localization function to ascertain the nature of bonding present in both the pristine and TM-intercalated composite systems. Intercalation of Cr, Mn, and Fe is found to result in the magnetic ground state. For Ti, Co, and Ni-intercalated systems, the starting trigonal symmetry has changed to a tetragonal symmetry. Co and Ni intercalated systems exhibit much higher (negative) formation energies compared to the other composite systems. In addition, nesting of the Fermi surface has been probed for the Co and Ni intercalated systems and observations indicate the possibility of the presence of charge density wave in the systems. A dispersion-corrected DFT study suggests that the van der Waals interaction is not likely to play a crucial role in determining the properties of both the pristine and TM-intercalated systems.
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Affiliation(s)
- Dhanshree Pandey
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - C Kamal
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Aparna Chakrabarti
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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7
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Ritter V, Genser J, Nazzari D, Bethge O, Bertagnolli E, Lugstein A. Silicene Passivation by Few-Layer Graphene. ACS APPLIED MATERIALS & INTERFACES 2019; 11:12745-12751. [PMID: 30864771 DOI: 10.1021/acsami.8b20751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The stabilization of silicene at ambient conditions is essential for its characterization, future processing, and device integration. Here, we demonstrate in situ encapsulation of silicene on Ag(111) by exfoliated few-layer graphene (FLG) flakes, allowing subsequent Raman analysis under ambient conditions. Raman spectroscopy measurements proved that FLG capping serves as an effective passivation, preventing degradation of silicene for up to 48 h. The acquired data are consistent with former in situ Raman measurements, showing two characteristic peaks, located at 216 and 515 cm-1. Polarization-dependent measurements allowed to identify the two modes as A and E, demonstrating that the symmetry properties of silicene are unaltered by the capping process.
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Affiliation(s)
- Viktoria Ritter
- Institute of Solid State Electronics , Technische Universität Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
| | - Jakob Genser
- Institute of Solid State Electronics , Technische Universität Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
| | - Daniele Nazzari
- Institute of Solid State Electronics , Technische Universität Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
| | - Ole Bethge
- Infineon Technologies Austria AG , Siemensstraße 2 , 9500 Villach , Austria
| | - Emmerich Bertagnolli
- Institute of Solid State Electronics , Technische Universität Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
| | - Alois Lugstein
- Institute of Solid State Electronics , Technische Universität Wien , Gußhausstraße 25-25a , 1040 Vienna , Austria
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8
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Nakano H, Tetsuka H, Spencer MJS, Morishita T. Chemical modification of group IV graphene analogs. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2018; 19:76-100. [PMID: 29410713 PMCID: PMC5795708 DOI: 10.1080/14686996.2017.1422224] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/25/2017] [Accepted: 12/25/2017] [Indexed: 05/31/2023]
Abstract
Mono-elemental two-dimensional (2D) crystals (graphene, silicene, germanene, stanene, and so on), termed 2D-Xenes, have been brought to the forefront of scientific research. The stability and electronic properties of 2D-Xenes are main challenges in developing practical devices. Therefore, in this review, we focus on 2D free-standing group-IV graphene analogs (graphene quantum dots, silicane, and germanane) and the functionalization of these sheets with organic moieties, which could be handled under ambient conditions. We highlight the present results and future opportunities, functions and applications, and novel device concepts.
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9
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Zhang X, Qiu X, Kong D, Zhou L, Li Z, Li X, Zhi L. Silicene Flowers: A Dual Stabilized Silicon Building Block for High-Performance Lithium Battery Anodes. ACS NANO 2017; 11:7476-7484. [PMID: 28692250 DOI: 10.1021/acsnano.7b03942] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nanostructuring is a transformative way to improve the structure stability of high capacity silicon for lithium batteries. Yet, the interface instability issue remains and even propagates in the existing nanostructured silicon building blocks. Here we demonstrate an intrinsically dual stabilized silicon building block, namely silicene flowers, to simultaneously address the structure and interface stability issues. These original Si building blocks as lithium battery anodes exhibit extraordinary combined performance including high gravimetric capacity (2000 mAh g-1 at 800 mA g-1), high volumetric capacity (1799 mAh cm-3), remarkable rate capability (950 mAh g-1 at 8 A g-1), and excellent cycling stability (1100 mA h g-1 at 2000 mA g-1 over 600 cycles). Paired with a conventional cathode, the fabricated full cells deliver extraordinarily high specific energy and energy density (543 Wh kgca-1 and 1257 Wh Lca-1, respectively) based on the cathode and anode, which are 152% and 239% of their commercial counterparts using graphite anodes. Coupled with a simple, cost-effective, scalable synthesis approach, this silicon building block offers a horizon for the development of high-performance batteries.
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Affiliation(s)
- Xinghao Zhang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
- University of Chinese Academy of Sciences , Beijing 100049, PR China
| | - Xiongying Qiu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
| | - Debin Kong
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
| | - Lu Zhou
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
| | - Zihao Li
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
| | - Xianglong Li
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
- University of Chinese Academy of Sciences , Beijing 100049, PR China
| | - Linjie Zhi
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190, PR China
- University of Chinese Academy of Sciences , Beijing 100049, PR China
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10
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Cortés N, Rosales L, Chico L, Pacheco M, Orellana PA. Enhancement of thermoelectric efficiency by quantum interference effects in trilayer silicene flakes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:015004. [PMID: 27830655 DOI: 10.1088/0953-8984/29/1/015004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In recent years, the enhancement of thermoelectric efficiencies has been accomplished in nanoscale systems by making use of quantum effects. We exploit the presence of quantum interference phenomena such as bound states in the continuum and Fano antiresonances in trilayer silicene flakes to produce sharp changes in the electronic transmission of the system. By applying symmetric gate voltages the thermoelectric properties can be tuned and, for particular flake lengths, a great enhancement of the figure of merit can be achieved. We show that the most favorable configurations are those in which the electronic transmission is dominated by the coupling of bound states to the continuum, tuned by an external gate.
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Affiliation(s)
- Natalia Cortés
- Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110 V, Valparaíso, Chile
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11
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Chowdhury S, Jana D. A theoretical review on electronic, magnetic and optical properties of silicene. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:126501. [PMID: 27753431 DOI: 10.1088/0034-4885/79/12/126501] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Inspired by the success of graphene, various two dimensional (2D) structures in free standing (FS) (hypothetical) form and on different substrates have been proposed recently. Silicene, a silicon counterpart of graphene, is predicted to possess massless Dirac fermions and to exhibit an experimentally accessible quantum spin Hall effect. Since the effective spin-orbit interaction is quite significant compared to graphene, buckling in silicene opens a gap of 1.55 meV at the Dirac point. This band gap can be further tailored by applying in plane stress, an external electric field, chemical functionalization and defects. In this topical theoretical review, we would like to explore the electronic, magnetic and optical properties, including Raman spectroscopy of various important derivatives of monolayer and bilayer silicene (BLS) with different adatoms (doping). The magnetic properties can be tailored by chemical functionalization, such as hydrogenation and introducing vacancy into the pristine planar silicene. Apart from some universal features of optical absorption present in all these 2D materials, the study on reflectivity modulation with doping (Al and P) concentration in silicene has indicated the emergence of some strong peaks having the robust characteristic of a doped reflective surface for both polarizations of the electromagnetic (EM) field. Besides this, attempts will be made to understand the electronic properties of silicene from some simple tight-binding Hamiltonian. We also point out the importance of shape dependence and optical anisotropy properties in silicene nanodisks and establish that a zigzag trigonal possesses the maximum magnetic moment. We also suggest future directions to be explored to make the synthesis of silicene and its various derivatives viable for verification of theoretical predictions. Although this is a fairly new route, the results obtained so far from experimental and theoretical studies in understanding silicene have shown enough significant promising features to open a new direction in the silicon industry, silicon based nano-structures in spintronics and in opto-electronic devices.
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Affiliation(s)
- Suman Chowdhury
- Department of Physics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009, India
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13
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Yaokawa R, Ohsuna T, Morishita T, Hayasaka Y, Spencer MJS, Nakano H. Monolayer-to-bilayer transformation of silicenes and their structural analysis. Nat Commun 2016; 7:10657. [PMID: 26847858 PMCID: PMC4748253 DOI: 10.1038/ncomms10657] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/06/2016] [Indexed: 11/21/2022] Open
Abstract
Silicene, a two-dimensional honeycomb network of silicon atoms like graphene, holds great potential as a key material in the next generation of electronics; however, its use in more demanding applications is prevented because of its instability under ambient conditions. Here we report three types of bilayer silicenes that form after treating calcium-intercalated monolayer silicene (CaSi2) with a BF4(-) -based ionic liquid. The bilayer silicenes that are obtained are sandwiched between planar crystals of CaF2 and/or CaSi2, with one of the bilayer silicenes being a new allotrope of silicon, containing four-, five- and six-membered sp(3) silicon rings. The number of unsaturated silicon bonds in the structure is reduced compared with monolayer silicene. Additionally, the bandgap opens to 1.08 eV and is indirect; this is in contrast to monolayer silicene which is a zero-gap semiconductor.
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Affiliation(s)
- Ritsuko Yaokawa
- TOYOTA Central R&D Labs, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Tetsu Ohsuna
- TOYOTA Central R&D Labs, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Tetsuya Morishita
- CD-FMat, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Yuichiro Hayasaka
- The Electron Microscopy Center, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | | | - Hideyuki Nakano
- TOYOTA Central R&D Labs, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan
- JST Presto, Kawaguchi 332-0012, Japan
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14
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Acun A, Zhang L, Bampoulis P, Farmanbar M, van Houselt A, Rudenko AN, Lingenfelder M, Brocks G, Poelsema B, Katsnelson MI, Zandvliet HJW. Germanene: the germanium analogue of graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:443002. [PMID: 26466359 DOI: 10.1088/0953-8984/27/44/443002] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recently, several research groups have reported the growth of germanene, a new member of the graphene family. Germanene is in many aspects very similar to graphene, but in contrast to the planar graphene lattice, the germanene honeycomb lattice is buckled and composed of two vertically displaced sub-lattices. Density functional theory calculations have revealed that free-standing germanene is a 2D Dirac fermion system, i.e. the electrons behave as massless relativistic particles that are described by the Dirac equation, which is the relativistic variant of the Schrödinger equation. Germanene is a very appealing 2D material. The spin-orbit gap in germanene (~24 meV) is much larger than in graphene (<0.05 meV), which makes germanene the ideal candidate to exhibit the quantum spin Hall effect at experimentally accessible temperatures. Additionally, the germanene lattice offers the possibility to open a band gap via for instance an externally applied electrical field, adsorption of foreign atoms or coupling with a substrate. This opening of the band gap paves the way to the realization of germanene based field-effect devices. In this topical review we will (1) address the various methods to synthesize germanene (2) provide a brief overview of the key results that have been obtained by density functional theory calculations and (3) discuss the potential of germanene for future applications as well for fundamentally oriented studies.
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Affiliation(s)
- A Acun
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500AE, Enschede, The Netherlands
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15
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Enhanced thermoelectric efficiency of porous silicene nanoribbons. Sci Rep 2015; 5:9514. [PMID: 25820162 PMCID: PMC4377624 DOI: 10.1038/srep09514] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/27/2015] [Indexed: 11/08/2022] Open
Abstract
There is a critical need to attain new sustainable materials for direct upgrade of waste heat to electrical energy via the thermoelectric effect. Here we demonstrate that the thermoelectric performance of silicene nanoribbons can be improved dramatically by introducing nanopores and tuning the Fermi energy. We predict that values of electronic thermoelectric figure of merit ZTe up to 160 are achievable, provided the Fermi energy is located approximately 100 meV above the charge neutrality point. Including the effect of phonons yields a value for the full figure of merit of ZT = 3.5. Furthermore the sign of the thermopower S can be varied with achievable values as high as S = +/− 500 μV/K. As a method of tuning the Fermi energy, we analyse the effect of doping the silicene with either a strong electron donor (TTF) or a strong electron acceptor (TCNQ) and demonstrate that adsorbed layers of the former increases ZTe to a value of 3.1, which is insensitive to temperature over the range 100 K – 400 K. This combination of a high, temperature-insensitive ZTe, and the ability to choose the sign of the thermopower identifies nanoporous silicene as an ideal thermoelectric material with the potential for unprecedented performance.
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16
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Liu H, Han N, Zhao J. Band gap opening in bilayer silicene by alkali metal intercalation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:475303. [PMID: 25351483 DOI: 10.1088/0953-8984/26/47/475303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Recently, bilayer and multilayer silicene have attracted increased attention following the boom of silicene, which holds great promise for future applications in microelectronic devices. Herein we systematically investigate all stacking configurations of bilayer silicene and the corresponding electronic properties. Strong coupling is found between two silicene layers, which destroys the Dirac cones in the band structures of pristine silicene and makes bilayer silicene sheets metallic. However, intercalation of alkali metal (especially potassium) can effectively decouple the interaction between two silicene layers. In the K-intercalated bilayer silicene (KSi4), the Dirac cones are recovered with a small band gap of 0.27 eV located about 0.55 eV below the Fermi level. Furthermore, intercalation of K(+) cations in bilayer silicene (K(+)Si4) results in a semiconductor with a moderate band gap of 0.43 eV, making it ideal for microelectronic applications.
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Affiliation(s)
- Hongsheng Liu
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, People's Republic of China
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Resta A, Leoni T, Barth C, Ranguis A, Becker C, Bruhn T, Vogt P, Le Lay G. Atomic structures of silicene layers grown on Ag(111): scanning tunneling microscopy and noncontact atomic force microscopy observations. Sci Rep 2014; 3:2399. [PMID: 23928998 PMCID: PMC3739010 DOI: 10.1038/srep02399] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 07/24/2013] [Indexed: 12/22/2022] Open
Abstract
Silicene, the considered equivalent of graphene for silicon, has been recently synthesized on Ag(111) surfaces. Following the tremendous success of graphene, silicene might further widen the horizon of two-dimensional materials with new allotropes artificially created. Due to stronger spin-orbit coupling, lower group symmetry and different chemistry compared to graphene, silicene presents many new interesting features. Here, we focus on very important aspects of silicene layers on Ag(111): First, we present scanning tunneling microscopy (STM) and non-contact Atomic Force Microscopy (nc-AFM) observations of the major structures of single layer and bi-layer silicene in epitaxy with Ag(111). For the (3 × 3) reconstructed first silicene layer nc-AFM represents the same lateral arrangement of silicene atoms as STM and therefore provides a timely experimental confirmation of the current picture of the atomic silicene structure. Furthermore, both nc-AFM and STM give a unifying interpretation of the second layer (√3 × √3)R ± 30° structure. Finally, we give support to the conjectured possible existence of less stable, ~2% stressed, (√7 × √7)R ± 19.1° rotated silicene domains in the first layer.
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Affiliation(s)
- Andrea Resta
- Aix-Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France.
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De Padova P, Avila J, Resta A, Razado-Colambo I, Quaresima C, Ottaviani C, Olivieri B, Bruhn T, Vogt P, Asensio MC, Le Lay G. The quasiparticle band dispersion in epitaxial multilayer silicene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:382202. [PMID: 23988580 DOI: 10.1088/0953-8984/25/38/382202] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The growth of multilayer silicene is an exciting challenge for the future of silicon nano-electronics. Here, we use angle-resolved photoemission spectroscopy to map the entire Brillouin zone (BZ) of (√3 × √3)R30° reconstructed epitaxial multilayer silicene islands, growing on top of the first (3 × 3) reconstructed silicene wetting layer, on Ag(111) substrates. We found Λ- and V-shape linear dispersions, which we relate to the π and π* bands of massless quasiparticles in multilayer silicene, at the BZ centre [Formula: see text] and at all the [Formula: see text] centres of the (√3 × √3)R30° Brillouin zones in the extended scheme, due to folding of the Dirac cones at the [Formula: see text] and [Formula: see text] points of the (1 × 1) silicene BZ. The Fermi velocity of ∼0.3 × 10(6) m s(-1) obtained is highly promising for potential silicene-based devices.
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Affiliation(s)
- Paola De Padova
- Consiglio Nazionale delle Ricerche-ISM, via Fosso del Cavaliere 100, I-00133 Roma, Italy.
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Avila J, De Padova P, Cho S, Colambo I, Lorcy S, Quaresima C, Vogt P, Resta A, Le Lay G, Asensio MC. Presence of gapped silicene-derived band in the prototypical (3 × 3) silicene phase on silver (111) surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:262001. [PMID: 23759650 DOI: 10.1088/0953-8984/25/26/262001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
By mapping the low-energy electronic dynamics using angle resolved photoemission spectroscopy (ARPES), we have shed light on essential electronic characteristics of the (3 × 3) silicene phase on Ag(111) surfaces. In particular, our results show a silicene-derived band with a clear gap and linear energy-momentum dispersion near the Fermi level at the Γ symmetry point of the (3 × 3) phase at several distinctive Brillouin zones. Moreover, we have confirmed that the large buckling of ~0.7 Å of this silicene structure induces the opening of a gap close to the Fermi level higher than at least 0.3 eV, in agreement with recent reported photoemission results. The two-dimensional character of the charge carriers has also been revealed by the photon energy invariance of the gapped silicene band, suggesting a limited silicene-silver hybridization, in disagreement with recent density-functional theory (DFT) predictions.
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Affiliation(s)
- J Avila
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, F-91192 Gif sur Yvette Cedex, France
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