Joint Laboratory of Police Equipment of UESTC

Chengdu, China

Joint Laboratory of Police Equipment of UESTC

Chengdu, China

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Wang Z.,University of Electronic Science and Technology of China | Wang Z.,Joint Laboratory of Police Equipment of UESTC | Su Q.,Hunan University | Yin G.Q.,Joint Laboratory of Police Equipment of UESTC | And 8 more authors.
Materials Chemistry and Physics | Year: 2014

Layered transition metal dichalcogenides with unique mechanical, electronic, optical, and chemical properties can be used for novel nanoelectronic and optoelectronic devices. Large-area monolayers synthesized using chemical vapor deposition are often polycrystals with many dislocations and grain boundaries (GBs). In the present paper, atomic structure and electronic properties of MX2 (M = Mo, W, Nb; X = S, Se) with the GBs were investigated using first principles based on density functional theory. Simulation results revealed that the zigzag-oriented GBs (which consist of pentagon/heptagons (5-7) pairs) were more stable than the armchair-oriented GBs (which consist of pentagon/heptagons (5-7-5-7) pairs). The GBs induced defect levels are located within the band gap for the semiconductor materials of MX2 (M = Mo, W; X = S, Se) monolayers, and the NbS2 and NbSe2 remained as metallic materials with GBs. Results provided a possible pathway to build these nano-layered materials into nanoelectronic devices. © 2014 Published by Elsevier B.V.


Wang Z.,University of Electronic Science and Technology of China | Wang Z.,Joint Laboratory of Police Equipment of UESTC | Su Q.,Hunan University | Shi J.,University of Electronic Science and Technology of China | And 8 more authors.
ACS Applied Materials and Interfaces | Year: 2014

Using first-principles calculation based on density functional theory, diffusion of Mg atom into α- and β-Sn was investigated. The diffusion barriers are 0.395 and 0.435 eV for an isolated Mg atom in the α- and β-Sn, respectively. However, the diffusion barriers of the Mg atom decrease in the α-Sn, whereas they increase in the β-Sn, when an additional Mg atom was inserted near the original diffusing Mg atom, which is mainly due to strong binding of Mg-Mg atoms in the β-Sn. Therefore, it is better to use the α-Sn, rather than the β-Sn, as an anode material for Mg ion batteries. © 2014 American Chemical Society.


Shi J.J.,University of Electronic Science and Technology of China | Shi J.J.,Joint Laboratory of Police Equipment of UESTC | Yin G.Q.,University of Electronic Science and Technology of China | Jing L.M.,University of Electronic Science and Technology of China | And 5 more authors.
International Journal of Modern Physics B | Year: 2014

Electrolytes with a high ionic conductivity are the prerequisite for the success of solid state rechargeable ion batteries. In this paper, density functional theory (DFT) calculations are applied in combination with a climbing-image nudged elastic band (CI-NEB) method to obtain the diffusion barriers of the lithium (Li) and sodium (Na) in stoichiometric AM2(PO4)3 (A=Li, Na, M=Ti, Sn and Zr) compounds. In the AM2(PO4)3, Li and Na ions occupy the interstitial sites, M1, which is coordinated by a trigonal antiprism of oxygen, and M2, which has a distorted eight-fold coordination. Results show that the diffusion barriers are closely related with the average bond length of A-O bond when the atom A occupies the M2 site in the AM2(PO4)3 compounds, and the diffusion barriers decrease with increasing the average bond length. Among the various types of the AM2(PO4)3 compounds, the AM2(PO4)3 has a good potential for solid electrolytes due to its low diffusion barriers for the Li and Na.. © World Scientific Publishing Company.


Wang Z.,University of Electronic Science and Technology of China | Wang Z.,Joint Laboratory of Police Equipment of UESTC | Yin G.Q.,Joint Laboratory of Police Equipment of UESTC | Jing L.,University of Electronic Science and Technology of China | And 4 more authors.
International Journal of Modern Physics B | Year: 2014

The tensile behavior of single crystalline GaN nanotube bundles was studied using classical molecular dynamics. Stillinger-Weber potential was used to describe the atom-atom interactions. The GaN bundles consisted of several individual GaN nanotubes with {100} side planes. The simulation results show that the nanotube bundles show a brittle to ductile transition (BDT) by changing the temperatures. The fracture of GaN nanotube bundles is ruled by a thermal activated process, higher temperature will lead to the decrease of the critical stress. At high temperatures the individual nanotube in the bundles interact with each other, which induces the increase of the critical stress of bundles. © 2014 World Scientific Publishing Company.

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