High-coverage stable structures of 3d transition metal intercalated bilayer graphene

Liao, Ji-Hai; Zhao, Yue; Tang, Jia-Jun; Yang, Xiao-Bao; Xu, Hu

doi:10.1039/c6cp01841f

Cited by 10 publications

(8 citation statements)

References 61 publications

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“…To further evaluate the dopant distribution and relative structural stability of Mn 4+ -doped Cs 2 SiF 6 , we performed theoretical calculations on the 2 × 2 × 2 supercell of Cs 2 SiF 6 with one to four Si 4+ ions replaced by corresponding Mn 4+ ions. To describe it, we have calculated the formation enthalpy Δ H ( x ) as , ,where E x , E 1 , and E 0 are the total energies with a coverage of x , 1, and 0. Herein, x represents the value of the ion numer ratio of Mn 4+ to Si 4+ .…”

Section: Resultsmentioning

confidence: 99%

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Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

et al. 2017

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Due to the unique narrow-band red emission and broadband blue light excitation, as well as milder synthesis conditions, Mn 4+ ion activated fluoride red phosphors show great promise for white light emitting diode (W-LED) applications. However, as the Mn 4+ emission belongs to a spin-forbidden transition ( 2 E g → 4 A 2 ), it is a fundamental challenge to synthesize these phosphors with a high external quantum efficiency (EQE) above 60%. Herein, a highly efficient and thermally stable red fluoride phosphor, Cs 2 SiF 6 :Mn 4+ , with a high internal quantum efficiency (IQE) of 89% and ultrahigh EQE of 71% is demonstrated. Furthermore, nearly 95% of the room-temperature IQE and EQE are maintained at 150 °C. The static and dynamic spectral measurements, as well as density functional theory (DFT) calculations, show that the excellent performance of Cs 2 SiF 6 :Mn 4+ is due to the Mn 4+ ions being evenly distributed in the host lattice Cs 2 SiF 6 . By employing Cs 2 SiF 6 :Mn 4+ as a red light component, stable 10 W high-power warm W-LEDs with a luminous efficiency of ∼110 lm/W could be obtained. These findings indicate that red phosphor Cs 2 SiF 6 :Mn 4+ may be a highly suitable candidate for fabricating high-performance high-power warm white LEDs.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

et al. 2017

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“…The C-C and C-TM equilibrium bond distances and d of the other BLG-TM layer materials are in agreement with the previous computational results. 31,33,34 The intercalation distances (d) in both the BLG-TM and bulk-BLG-TM are Figure 5 and the trend is similar for the bilayer and bulk analogs. To estimate the likehood of the synthesis of these materials, we have calculated the binding energy (ΔE b ) of both systems, BLG-TM and bulk-BLG-TM.…”

Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Tuning the Dirac Cone of Bilayer and Bulk Structure Graphene by Intercalating First Row Transition Metals Using First-Principles Calculations

Pakhira

Mendoza-Cortés

2018

J. Phys. Chem. C

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Modern nanoscience has focused on two-dimensional (2D) layer structure materials which have garnered tremendous attention due to their unique physical, chemical and electronic properties since the discovery of graphene in 2004. Recent advancement in graphene nanotechnology opens a new avenue of creating 2D bilayer graphene (BLG) intercalates. Using first-principles DFT techniques, we have designed 20 new materials in-silico by intercalating first row transition metals (TMs) with BLG, i.e. 10 layered structure and 10 bulk crystal structures of TM intercalated in BLG. We investigated the equilibrium structure and electronic properties of layered and bulk structure BLG intercalated with first row TMs (Sc-Zn). The present DFT calculations show that the 2p z sub-shells of C atoms in graphene and the 3d yz sub-shells of the TM atoms provide the electron density near the Fermi level controlling the material properties of the BLG-intercalated materials. This article highlights how the Dirac point moves in both the BLG and bulk-BLG given a different TM intercalated materials. The implications of controllable electronic structure and properties of intercalated BLG-TM for future device applications are discussed. This work opens up new avenues for the efficient production of two-dimensional and three-dimensional carbon-based intercalated materials with promising future applications in nanomaterial science. Structures; Density of States (DOSs); DFT-D.Recent advancement in graphene nanotechnology opens a new avenue of creating few-layer graphene intercalates. Combining layers of 2D materials in particular sequences to form 4 multilayer structures provides an avenue for the manipulation of mechanical and electronic properties and for creating heterostructure devices. 3,4,22,23,27 As stated earlier, among all the approaches, the intercalation method is one of the best methods to control the material properties of graphene, BLG and graphite. 4,19,24,28,29 Alkalimetal intercalated graphite and graphene have been intensively studied for decades, where alkali metal atoms are found to form ordered structures at the hollow sites of hexagonal carbon rings. To the best of our knowledge, the intercalation of graphene or graphite was studied mainly by using alkali atoms or ions (Li, Na and K) which has many important applications in modern science 19-21 such as Li-ion or Na-ion. battery 28,30 However, intercalation of transition metal (TM) atoms into 2D layered structure and 3D bulk structure materials (such as bilayer graphene or graphite) has not been studied systematically and extensively yet. The few reported studies have shown that they provide rich electrical, material and chemical properties that are distinctly different from those of pristine materials. 4 In particular, intercalation into bulk BLG has attracted special attention, since graphite intercalation compounds show various fascinating physical properties such as superconductivity and magnetism. 19,20,26 Bui et al. 31 carried out a theoretical investigation on 2D BLG-C...

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“…A theoretical investigation of BLG intercalated with Cr was carried out using DFT, which found that BLG-Cr layer material is ferromagnetic. [27] Using first-principles calculations, Liao et al [30] investigated various stable BLG structures intercalated with Sc and Ti. They found that the strain was important for the stability of high-coverage TM in BLG.…”

Section: Introductionmentioning

confidence: 99%

Dirac cone in two dimensional bilayer graphene by intercalation with V, Nb, and Ta transition metals

Pakhira

Lucht

Mendoza-Cortés

2018

The Journal of Chemical Physics

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Bilayer graphene (BLG) is a semiconductor whose band gap and properties can be tuned by various methods such as doping or applying gate voltage. Here, we show how to tune electronic properties of BLG by intercalation of transition metal (TM) atoms between two monolayer graphene (MLG) using a novel dispersion-corrected first-principle density functional theory (DFT) approach. We intercalated V, Nb, and Ta atoms between two MLG. We found that the symmetry, the spin, and the concentration of TM atoms in BLG-intercalated materials are the important parameters to control and to obtain a Dirac cone in their band structures. Our study reveals that the BLG intercalated with one vanadium (V) atom, BLG-1V, has a Dirac cone at the K-point. In all the cases, the present DFT calculations show that the 2p sub-shells of C atoms in graphene and the 3d sub-shells of the TM atoms provide the electron density near the Fermi energy level (E) which controls the material properties. Thus, we show that out-of-plane atoms can influence in-plane electronic densities in BLG and enumerate the conditions necessary to control the Dirac point. This study offers insight into the physical properties of 2D BLG intercalated materials and presents a new strategy for controlling the electronic properties of BLG through TM intercalation by varying the concentration and spin arrangement of the metals resulting in various conducting properties, which include: metal, semi-metal and semiconducting states.

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High-coverage stable structures of 3d transition metal intercalated bilayer graphene

Cited by 10 publications

References 61 publications

Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

Tuning the Dirac Cone of Bilayer and Bulk Structure Graphene by Intercalating First Row Transition Metals Using First-Principles Calculations

Dirac cone in two dimensional bilayer graphene by intercalation with V, Nb, and Ta transition metals

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High-coverage stable structures of 3d transition metal intercalated bilayer graphene

Cited by 10 publications

References 61 publications

Highly Efficient and Stable Narrow-Band Red Phosphor Cs2SiF6:Mn4+ for High-Power Warm White LED Applications

Highly Efficient and Stable Narrow-Band Red Phosphor Cs2SiF6:Mn4+ for High-Power Warm White LED Applications

Tuning the Dirac Cone of Bilayer and Bulk Structure Graphene by Intercalating First Row Transition Metals Using First-Principles Calculations

Dirac cone in two dimensional bilayer graphene by intercalation with V, Nb, and Ta transition metals

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Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications

Highly Efficient and Stable Narrow-Band Red Phosphor Cs₂SiF₆:Mn⁴⁺ for High-Power Warm White LED Applications