| 1. |
- Jiang, Guanzhong, et al.
(författare)
-
Exploring pristine and Li-doped Mg2NiH4 compounds with potential lithium-storage properties : Ab initio insight
- 2018
-
Ingår i: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 746, s. 140-146
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, pure and Li-doped Mg2NiH4 hydrides are explored for potential Li-ion battery conversion anode materials applications from state-of-the-art Density functional theory. The most thermodynamically stable Li-doped Mg2NiH4 structure is determined, which possesses a smaller band gap than pure material and owns a theoretical specific capacity of 975.35 mA h g(-1) and an average voltage of 0.437 V (vs. Li+/Li-0). The Li-doping also improves the diffusion behavior of Li-ion in electrode material especially at 300 K, which implies the promising rate capability of the device at room temperature when the anode material is doped utilizing Li element. The non-empirical values of diffusion coefficients of Li-ion in both pure and Li-doped Mg2NiH4 system are also quantitatively determined from ab initio molecular dynamics. After Li-doping, the diffusion coefficient of Li-ion in the electrode is evidently increased to 1.791 x 10(-9) m(2) s(-1) from the pristine 1.431 x 10(-9) m(2) s(-1) at 300 K and the Li-ion conductivity is also increased. This theoretical study is proposed to encourage the design and experimental modification of better light-metal based hydrides for Li-ion battery conversion anodes applications.
|
|
| 2. |
- Nie, Xi, et al.
(författare)
-
Structural Evolution of AlN Nanoclusters and the Elemental Chemisorption Characteristics : Atomistic Insight
- 2019
-
Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 9:10
-
Tidskriftsartikel (refereegranskat)abstract
- A theoretical insight into the structural evolution of AlN atomic clusters and the chemisorption of several common alloying elements on a large cluster has been performed in the framework of state-of-the-art density functional theory calculations. We report the findings that the longitudinal growth takes precedence during the early stage of structural evolution of small AlN clusters, when the longitudinal dimension becomes stable, the AlN cluster proceeds with cross-growth and blossoms into the large-size Al60N60. Upon the growth of clusters, the structures tend to become well-knit gradually. As for the evolution of electronic structures of AlN clusters through the HSE06 calculations, the density of states curves become more and more nondiscrete with the atomic structures evolving from small to large size and tend to resemble that of the Wurtzite AlN. The chemisorption characteristics of the large Al60N60 cluster towards different elements such as Al, N, Fe and Cu are also theoretically unveiled, in which it is interestingly found that the N and Cu atoms are likely to be adsorbed similarly at the growth edge position of the Al60N60 cluster and the density of states curves of these two chemisorption systems near the Fermi level also show some interesting similarities.
|
|
| 3. |
- Nie, Xi, et al.
(författare)
-
Theoretical prediction of a novel aluminum nitride nanostructure : Atomistic exposure
- 2019
-
Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 45:17, s. 23690-23693
-
Tidskriftsartikel (refereegranskat)abstract
- Aluminum nitride has significant prospect as a kind of ceramic material in applications such as semiconductors, sensors and other electronic devices. In this work, a novel AlN nanostructure is reported in terms of the optimized atomic structure, energetics, phonon dispersions and electronic structures employing the state-of-the-art Density functional theory (DFT). The interesting propeller-shaped AlN nanowire structure is determined with its detailed bond lengths and bond angles identified. In this structure, the orbital hybridization of Al and N atoms with coordination number of three is sp2, and hybridization of Al and N atoms with coordination number of four and five are sp3 and sp3d, respectively. The binding energy and work function of the novel AlN nanostructure are -4.855 eV and -5.326 eV, respectively. The charge distribution inside the novel structure has also been explored through the differential charge density and the Bader charge analysis. The nanostructure has a band gap of 2.5 eV with its deep electronic structure revealed. This theoretical study proposes a new type of AlN nanowire and will make guidance for experimentalists to design novel III-V group ceramic nanostructures for semiconductor or other functional applications.
|
|
| 4. |
- Ouyang, Tianhong, et al.
(författare)
-
Effect of defects on adsorption characteristics of AlN monolayer towards SO2 and NO2 : Ab initio exposure
- 2018
-
Ingår i: Applied Surface Science. - : ELSEVIER SCIENCE BV. - 0169-4332 .- 1873-5584. ; 462, s. 615-622
-
Tidskriftsartikel (refereegranskat)abstract
- Density functional theory (DFT) calculations have been employed to explore the adsorption properties of pristine and vacancy-defective AlN monolayer towards SO2 and NO2 in terms of their adsorption energies and electronic structures. The calculations with van der Waals effect are performed to study the binding mechanism of pristine and vacancy-defective AlN nanosheet with SO2 and NO2. Three types of vacancy defects are considered including Al-monovacancy, N-monovacancy and divacancy. The adsorption energies of vacancy-defective AlN monolayer towards SO2 and NO2 are found to be much higher than that of pristine nanosheet. The equilibrium adsorption sites and configurations of the gas molecules on AlN nanosheets are determined. The Bader charge transfer analysis reveals that a considerable amount of charge is transferred from the vacancy-defective AlN nanosheets to the gases leading to the increase of adsorption energies. The results of difference charge densities, band structures, electronic density of states and work function further give insight into adsorption energies. The dramatical changes of electronic band structures after gas interaction suggest the excellent adsorption properties of vacancy-defective AlN monolayer towards SO2 and NO2.
|
|
| 5. |
- Ouyang, Tianhong, et al.
(författare)
-
First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets
- 2018
-
Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 439, s. 196-201
-
Tidskriftsartikel (refereegranskat)abstract
- The optimized atomic structures, energetics and electronic structures of toxic gas CO adsorption systems on pristine, C-doped and N-vacancy defected h-AlN nanosheets respectively have been investigated using Density functional theory (DFT-D2 method) to explore their potential gas detection or sensing capabilities. It is found that both the C-doping and the N-vacancy defect improve the CO adsorption energies of AlN nanosheet (from pure -3.847 eV to -5.192 eV and -4.959 eV). The absolute value of the system band gap change induced by adsorption of CO can be scaled up to 2.558 eV or 1.296 eV after C-doping or N-vacancy design respectively, which is evidently larger than the value of 0.350 eV for pristine material and will benefit the robustness of electronic signals in potential gas detection. Charge transfer mechanisms between CO and the AlN nanosheet have been presented by the Bader charge and differential charge density analysis to explore the deep origin of the underlying electronic structure changes. This theoretical study is proposed to predict and understand the CO adsorption properties of the pristine and defected h-AlN nanosheets and would help to guide experimentalists to develop better AlN-based two-dimensional materials for efficient gas detection or sensing applications in the future.
|
|
| 6. |
- Qian, Zhao, et al.
(författare)
-
Revisiting Mg-Mg2Ni System from Electronic Perspective
- 2017
-
Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 7:11
-
Tidskriftsartikel (refereegranskat)abstract
- Both Mg and Mg2Ni are promising electrode materials in conversion-type secondary batteries. Earlier studies have shown their single-phase prospects in electro-devices, while in this work, we have quantitatively reported the electronic properties of their dual-phase materials, that is, Mg-Mg2Ni alloys, and analyzed the underlying reasons behind the property changes of materials. The hypoeutectic Mg-Mg2Ni alloys are found to be evidently more conductive than the hypereutectic Mg-Mg2Ni system. The density functional theory (DFT) calculations give the intrinsic origin of electronic structures of both Mg2Ni and Mg. The morphology of quasi-nanoscale eutectics is another factor that can affect the electronic properties of the investigated alloy system; that is, the electrical property change of the investigated alloys system is due to a combination of the intrinsic property difference between the two constituting phases and the change of eutectic microstructures that affect electron scattering. In addition, regarding the Mg-Mg2Ni alloy design for device applications, the electronic property and mechanical aspect should be well balanced.
|
|
