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Journal ArticleDOI

Unique Omnidirectional Negative Poisson’s Ratio in δ-Phase Carbon Monochalcogenides

12 Feb 2021-Journal of Physical Chemistry C (American Chemical Society (ACS))-Vol. 125, Iss: 7, pp 4133-4138
TL;DR: In this article, a two-dimensional δ-phase carbon monochalcoated carbon dioxide (CMCO) was proposed for nanomechanical applications using first-principles calculations.
Abstract: Auxetic materials (negative Poisson’s ratio) are of exceptional importance for nanomechanical applications. Using first-principles calculations, we propose two-dimensional δ-phase carbon monochalco...
Citations
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Journal ArticleDOI
TL;DR: In this paper, the structural and electronic properties of organic molecule doped MoSi 2N4 monolayers were investigated using first principles calculations to study the effect of molecular doping.
Abstract: MoSi2N4 is a recently developed 2D material that exhibits remarkable thermal, mechanical, electronic, and optical properties. We used first principles calculations to study the structural and electronic properties of organic molecule doped MoSi 2N4 monolayers. Effective p-doping was achieved by molecular doping with tetracyanoquinodimethane and tetracyanoethylene, while n-doping was achieved by molecular doping with tetrathiafulvalene. The doping gap of tetrathiafulvalene-doped MoSi2N4 was successfully modulated by the application of an external electric field, which resulted in effective n-doping. Furthermore, molecular doping injects additional carriers into the host, which is beneficial for enhancing the performance of MoSi2N4 in nanoelectronic devices. Our results demonstrate the importance of molecular doping in tuning the electronic properties of MoSi 2N4 and broadening its applications.

92 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the properties of the heterostructure constructed by Hf2CO2, AlN and GaN and provided theoretical guidance for the design of heterostructures for use as photocatalytic and photovoltaic devices.
Abstract: After the discovery of graphene, a lot of research has been conducted on two-dimensional (2D) materials. In order to increase the performance of 2D materials and expand their applications, two different layered materials are usually combined by van der Waals (vdW) interactions to form a heterostructure. In this work, based on first-principles calculation, some charming properties of the heterostructure constructed by Hf2CO2, AlN and GaN are addressed. The results show that Hf2CO2/AlN and Hf2CO2/GaN vdW heterostructures can keep their original band structure shape and have strong thermal stability at 300 K. In addition, the Hf2CO2/MN heterostructure has I-type band alignment structure, which can be used as a promising light-emitting device material. The charge transfer between the Hf2CO2 and AlN (or GaN) monolayers is 0.1513 (or 0.0414) |e|. The potential of Hf2CO2/AlN and Hf2CO2/GaN vdW heterostructures decreases by 6.445 eV and 3.752 eV, respectively, across the interface. Furthermore, both Hf2CO2/AlN and Hf2CO2/GaN heterostructures have remarkable optical absorption capacity, which further shows the application prospect of the Hf2CO2/MN heterostructure. The study of this work provides theoretical guidance for the design of heterostructures for use as photocatalytic and photovoltaic devices.

30 citations

Journal ArticleDOI
Zhen Cui, Kunqi Yang, Kai Ren, Shuang Zhang, Lu Wang 
TL;DR: The magnetic and electronic properties of metal atoms adsorbedbedding MoSi2N4 monolayer have been systematically investigated by density functional theory as mentioned in this paper , and the results reveal that the most stable sites of MoSiN4-monolayer adaption by various metal are diverse.

28 citations

Journal ArticleDOI
TL;DR: In this article, the electronic and magnetic properties of two-dimensional (2D) CrI3 adsorbed by gas molecules, CO, H 2, H2O and N2, were systematically calculated by means of first-principles simulation.
Abstract: Possessing long-range FM order and tunable interlayer magnetic coupling, extensive investigations of monolayered ferromagnetic chromium triiodide (CrI3) have been developed. In this work, by means of first-principles simulation, we systematically calculated the electronic and magnetic characteristic of two-dimensional (2D) CrI3 adsorbed by gas molecules, CO, H2, H2O and N2, which can provide theoretical guidance to modulate the desired properties of this layered material. The results show that the adsorption of those gas molecules can significantly enhance FM couplings of monolayer CrI3. In particular, the N2 adsorption can remarkably improve the Curie temperatures of the pristine CrI3 monolayer by about 2.6 times. We also hope that our findings can provide more interest around the recently studied 2D FM semiconductors.

26 citations


Cites background from "Unique Omnidirectional Negative Poi..."

  • ...the properties of 2D materials, such as external strain [37, 38],...

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Journal ArticleDOI
TL;DR: In this article , the configurations of nine different non-metals doped silicon carbide (NM-SiC) were structured by using the density functional theory (DFT).
Abstract: The configurations of nine different non-metals doped silicon carbide (NM-SiC) were structured by using the density functional theory (DFT). The magnetic, electronic, and optical properties of each NM-SiC are investigated at the most stable structure with the maximum binding energy. Although the O-, Si-, and S-SiC systems are still non-magnetic semiconductors, the N- and P-SiC systems have the properties of the magnetic semiconductors. The H-, F-, and Cl-SiC systems exhibit the half-metal behaviors, while the B-SiC system converts to magnetic metal. The redistribution of charges occurs between non-metals atoms and adjacent C atoms. For the same doping position, the more charges are transferred, the greater the binding energy of the NM-SiC system. The work function of the NM-SiC systems is also adjusted by the doping of NM atoms, and achieves the minimum 3.70 eV in the P-SiC, just 77.1% of the original SiC. The absorption spectrum of the NM-SiC systems occurs red-shift in the ultraviolet light region, accompanying the decrease of absorption coefficient. These adjustable magnetic, electronic, and optical performances of NM-SiC expand the application fields of two-dimensional (2D) SiC, especially in designing field emission and spintronics devices.

25 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Abstract: The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Bl\"ochl's projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addition, critical tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed core all electron methods. These tests include small molecules $({\mathrm{H}}_{2}{,\mathrm{}\mathrm{H}}_{2}{\mathrm{O},\mathrm{}\mathrm{Li}}_{2}{,\mathrm{}\mathrm{N}}_{2}{,\mathrm{}\mathrm{F}}_{2}{,\mathrm{}\mathrm{BF}}_{3}{,\mathrm{}\mathrm{SiF}}_{4})$ and several bulk systems (diamond, Si, V, Li, Ca, ${\mathrm{CaF}}_{2},$ Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.

57,691 citations

Journal ArticleDOI
Changgu Lee1, Xiaoding Wei1, Jeffrey W. Kysar1, James Hone1, James Hone2 
18 Jul 2008-Science
TL;DR: Graphene is established as the strongest material ever measured, and atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.
Abstract: We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

18,008 citations

Journal ArticleDOI
TL;DR: A bilayer architecture comprising the key features of mesoscopic and planar structures obtained by a fully solution-based process is reported, providing important progress towards the understanding of the role of solution-processing in the realization of low-cost and highly efficient perovskite solar cells.
Abstract: The performance of solar cells based on organic–inorganic perovskites strongly depends on the device architecture and processing conditions. It is now shown that solvent engineering enables the deposition of very dense perovskite layers on mesoporous titania, leading to photovoltaic devices with a high light-conversion efficiency and no hysteresis.

5,684 citations

Journal ArticleDOI
TL;DR: In this paper, a modification of the Nose-Hoover dynamics is proposed which includes not a single thermostat variable but a chain of variables, Nose chains, which gives the canonical distribution where the simple formalism fails.
Abstract: Nose has derived a set of dynamical equations that can be shown to give canonically distributed positions and momenta provided the phase space average can be taken into the trajectory average, i.e., the system is ergodic [S. Nose, J. Chem. Phys. 81, 511 (1984), W. G. Hoover, Phys. Rev. A 31, 1695 (1985)]. Unfortunately, the Nose–Hoover dynamics is not ergodic for small or stiff systems. Here a modification of the dynamics is proposed which includes not a single thermostat variable but a chain of variables, Nose–Hoover chains. The ‘‘new’’ dynamics gives the canonical distribution where the simple formalism fails. In addition, the new method is easier to use than an extension [D. Kusnezov, A. Bulgac, and W. Bauer, Ann. Phys. 204, 155 (1990)] which also gives the canonical distribution for stiff cases.

4,053 citations

Journal ArticleDOI
27 Feb 1987-Science
TL;DR: A novel foam structure is presented, which exhibits a negative Poisson's ratio, and such a material expands laterally when stretched, in contrast to ordinary materials.
Abstract: A novel foam structure is presented, which exhibits a negative Poisson's ratio. Such a material expands laterally when stretched, in contrast to ordinary materials.

2,871 citations