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Luo, Wei
Publications (10 of 42) Show all publications
Yang, X., Li, H., Hu, M., Liu, Z., Wärnå, J., Cao, Y., . . . Luo, W. (2018). Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds. Physica. E, Low-Dimensional systems and nanostructures, 98, 23-28
Open this publication in new window or tab >>Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds
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2018 (English)In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 98, p. 23-28Article in journal (Refereed) Published
Abstract [en]

A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zr-O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (nu) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Signal-wall ZrO2 nanotubes, Mechanical properties, Finite element method, Poisson's ratio
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-347532 (URN)10.1016/j.physe.2017.10.005 (DOI)000425118100005 ()
Funder
Swedish Research Council
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-04Bibliographically approved
Tsuppayakorn-aek, P., Luo, W., Ahuja, R. & Bovornratanaraks, T. (2018). The High-Pressure Superconducting Phase of Arsenic. Scientific Reports, 8, Article ID 3026.
Open this publication in new window or tab >>The High-Pressure Superconducting Phase of Arsenic
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3026Article in journal (Refereed) Published
Abstract [en]

Ab initio random structure searching (AIRSS) technique is predicted a stable structure of arsenic (As). We find that the body-centered tetragonal (bct) structure with spacegroup I4(1)/acd to be the stable structure at high pressure. Our calculation suggests transition sequence from the simple cubic (sc) structure transforms into the host-guest (HG) structure at 41 GPa and then into the bct structure at 81 GPa. The bct structure has been calculated using ab initio lattice dynamics with finite displacement method confirm the stability at high pressure. The spectral function alpha F-2 of the bct structure is higher than those of the body-centered cubic (bcc) structure. It is worth noting that both bct and bcc structures share the remarkable similarity of structural and property. Here we have reported the prediction of temperature superconductivity of the bct structure, with a T-c of 4.2 K at 150 GPa.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348108 (URN)10.1038/s41598-018-20088-8 (DOI)000424985800064 ()29445106 (PubMedID)
Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2018-04-11Bibliographically approved
Sun, W., Luo, W., Feng, Q. & Ahuja, R. (2017). Anisotropic distortion and Lifshitz transition in alpha-Hf under pressure. Physical Review B, 95(11), Article ID 115130.
Open this publication in new window or tab >>Anisotropic distortion and Lifshitz transition in alpha-Hf under pressure
2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 11, article id 115130Article in journal (Refereed) Published
Abstract [en]

In this work we report a theoretical investigation on behavior of the elastic constant C-44 and the transverse optical phonon mode E(2)g of a-Hf under pressure within the density functional theory. In contrast to many other reported transition metals, the above two quantities do not show a synchronous relation as pressure increases. Below 13 GPa, an opposite shifting tendency has been observed. However, once the pressure is raised above 13 GPa, the trend is pulled back to be consistent. This anomalous behavior is figured out to be caused by the large lattice anisotropy of the c/a ratio along with the elastic anisotropy. The synchronous behavior is found to be in accordance with the behavior of c/a ratio with increased pressure. In our band-structure investigations the electronic topological transition has been discovered at 10 GPa, which relates to the change of c/a ratio suggested by recent literature. The presence of the Van Hove singularity shown in the densities of states has been identified and regarded as the origin of the variation of C-44 and E(2)g.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2017
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-320218 (URN)10.1103/PhysRevB.95.115130 (DOI)000396273400004 ()
Funder
Swedish Research Council
Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2017-11-29Bibliographically approved
Naqvi, S. R., Hussain, T., Luo, W. & Ahuja, R. (2017). Exploring Doping Characteristics of Various Adatoms on Single-Layer Stanene. The Journal of Physical Chemistry C, 121(14), 7667-7676
Open this publication in new window or tab >>Exploring Doping Characteristics of Various Adatoms on Single-Layer Stanene
2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 14, p. 7667-7676Article in journal (Refereed) Published
Abstract [en]

We have performed first-principles calculations based on density functional theory to investigate the doping characteristics of 31 different adatoms on stanene monolayer, which includes the elements of alkali metals (AM), alkaline earth metals (AEM), transition metals (TMs), and groups III-VII. The most stable configurations of all the dopants have been explored by calculating and comparing binding energies of all the possible binding sites. To comment on the uniform distribution of adatoms on stanene, the adsorption energies (E-ads) of adatoms have been compared with their experimental cohesive energies (E-c,) in the bulk phase.A further comparison reveals that the binding energies of most of the studied adatoms on stanene are much stronger than other group IV monolayers. Apart from structural and binding characteristics, bond lengths, adatom adatom distance, charge-transfer mechanism, electronic properties, and work function have also been explored in pristine and doped monolayers. The strong adsorption of adatoms on stanene, tunable electronic properties, and formation of dumbbell structures in the case of AEM and TM shows that doped stanene sheets are worth further exploration.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-322817 (URN)10.1021/acs.jpcc.7b00468 (DOI)000399629000011 ()
Funder
Swedish Research CouncilStandUpCarl Tryggers foundation
Available from: 2017-05-30 Created: 2017-05-30 Last updated: 2017-05-30Bibliographically approved
Yang, X., Li, H., Ahuja, R., Kang, T. & Luo, W. (2017). Formation and electronic properties of palladium hydrides and palladium-rhodium dihydride alloys under pressure. Scientific Reports, 7, Article ID 3520.
Open this publication in new window or tab >>Formation and electronic properties of palladium hydrides and palladium-rhodium dihydride alloys under pressure
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 3520Article in journal (Refereed) Published
Abstract [en]

We present the formation possibility for Pd-hydrides and Pd-Rh hydrides system by density functional theory (DFT) in high pressure upto 50 GPa. Calculation confirmed that PdH2 in face-centered cubic (fcc) structure is not stable under compression that will decomposition to fcc-PdH and H-2. But it can be formed under high pressure while the palladium is involved in the reaction. We also indicate a probably reason why PdH2 can not be synthesised in experiment due to PdH is most favourite to be formed in Pd and H-2 environment from ambient to higher pressure. With Rh doped, the Pd-Rh dihydrides are stabilized in fcc structure for 25% and 75% doping and in tetragonal structure for 50% doping, and can be formed from Pd, Rh and H-2 at high pressure. The electronic structural study on fcc type PdxRh1-xH2 indicates the electronic and structural transition from metallic to semi-metallic as Pd increased from x = 0 to 1.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2017
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-329676 (URN)10.1038/s41598-017-02617-z (DOI)000403318400074 ()28615686 (PubMedID)
Funder
Swedish InstituteSwedish Foundation for Strategic Research Swedish Research Council
Available from: 2017-09-19 Created: 2017-09-19 Last updated: 2017-09-19Bibliographically approved
Naqvi, S. R., Rao, G. S., Luo, W., Ahuja, R. & Hussain, T. (2017). Hexagonal Boron Nitride (h-BN) Sheets Decorated with OLi, ONa, and Li2F Molecules for Enhanced Energy Storage. ChemPhysChem, 18(5), 513-518
Open this publication in new window or tab >>Hexagonal Boron Nitride (h-BN) Sheets Decorated with OLi, ONa, and Li2F Molecules for Enhanced Energy Storage
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2017 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 18, no 5, p. 513-518Article in journal (Refereed) Published
Abstract [en]

First-principles electronic structure calculations were carried out on hexagonal boron nitride (h-BN) sheets functionalized with small molecules, such as OLi, ONa, and Li2F, to study their hydrogen (H-2) storage properties. We found that OLi and ONa strongly adsorb on h-BN sheets with reasonably large inter-adsorbent separations, which is desirable for H-2 storage. Ab initio molecular dynamics (MD) simulations further confirmed the structural stability of OLi-BN and ONa-BN systems at 400K. On the other hand, Li2F molecules form clusters over the surface of h-BN at higher temperatures. We performed a Bader charge investigation to explore the nature of binding between the functionalized molecules and h-BN sheets. The density of states (DOS) revealed that functionalized h-BN sheets become metallic with two-sided coverage of each type of molecules. Hydrogenation of OLi-BN and ONa-BN revealed that the functionalized systems adsorb multiple H-2 molecules around the Li and Na atoms, with H-2 adsorption energies ranging from 0.20 to 0.28eV, which is desirable for an efficient H-2 storage material.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
electronic properties, functionalization, hydrogenation, nanosheets, structural stability
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-320260 (URN)10.1002/cphc.201601063 (DOI)000395423100011 ()28098421 (PubMedID)
Funder
Swedish Research CouncilStandUpSwedish Energy AgencyAustralian Research Council
Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2017-04-18Bibliographically approved
Parlak, O., Mishra, Y. K., Grigoriev, A., Mecklenburg, M., Luo, W., Keene, S., . . . Tiwari, A. (2017). Hierarchical Aerographite nano-microtubular tetrapodal networks based electrodes as lightweight supercapacitor. Nano Energy, 34, 570-577
Open this publication in new window or tab >>Hierarchical Aerographite nano-microtubular tetrapodal networks based electrodes as lightweight supercapacitor
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2017 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 34, p. 570-577Article in journal (Refereed) Published
Abstract [en]

A great deal of interest has been paid to the application of carbon-based nano-and microstructured materials as electrodes due to their relatively low-cost production, abundance, large surface area, high chemical stability, wide operating temperature range, and ease of processing including many more excellent features. The nanostructured carbon materials usually offer various micro-textures due to their varying degrees of graphitisation, a rich variety in terms of dimensionality as well as morphologies, extremely large surface accessibility and high electrical conductivity, etc. The possibilities of activating them by chemical and physical methods allow these materials to be produced with further higher surface area and controlled distribution of pores from nanoscale upto macroscopic dimensions, which actually play the most crucial role towards construction of the efficient electrode/electrolyte interfaces for capacitive processes in energy storage applications. Development of new carbon materials with extremely high surface areas could exhibit significant potential in this context and motivated by this in present work, we report for the first time the utilization of ultralight and extremely porous nano-microtubular Aerographite tetrapodal network as a functional interface to probe the electrochemical properties for capacitive energy storage. A simple and robust electrode fabrication strategy based on surface functionalized Aerographite with optimum porosity leads to significantly high specific capacitance (640 F/g) with high energy (14.2 Wh/kg) and power densities (9.67x103 W/kg) which has been discussed in detail.

Keywords
Hierarchical nanocarbons, Tubular Aerographite, Electrodes, Porous interfaces, Supercapacitors
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-322849 (URN)10.1016/j.nanoen.2017.03.004 (DOI)000400383300061 ()
Funder
Knut and Alice Wallenberg Foundation, KAW 2014.0387German Research Foundation (DFG), AD 183/17-1German Research Foundation (DFG), AD 183/20-2German Research Foundation (DFG), SFB 986M3 TP B1Swedish Research Council, VR-2016-06014
Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2017-06-07Bibliographically approved
Naqvi, S. R., Hussain, T., Panigrahi, P., Luo, W. & Ahuja, R. (2017). Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping. RSC Advances, 7(14), 8598-8605
Open this publication in new window or tab >>Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping
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2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 14, p. 8598-8605Article in journal (Refereed) Published
Abstract [en]

We report, for the first time we believe, a detailed investigation on hydrogen storage efficiency of scandium (Sc) decorated boron carbide (BC3) sheets using spin-polarized density functional theory (DFT). We analyzed the energetics of Sc adsorption and explored the most favorable adsorption sites of Sc on BC3 sheets with 3.12%, 6.25%, and 12.5% coverage effects. Our investigations revealed that Sc strongly binds on pristine BC3 sheet, with a minimum binding energy of similar to 5 eV, which is robust enough to hinder Sc-Sc metal clustering. Sc, the lightest transition metal, adsorbs a large number of H-2 molecules per atom, resulting in a reasonable storage capacity. With 12.5% Sc-coverage, functionalized BC3 sheets could attain a H2 storage capacity of 5.5 wt% with binding energies suitable for a practical H-2 storage medium.

National Category
Chemical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-317700 (URN)10.1039/c6ra24890j (DOI)000393758700061 ()
Funder
Swedish Research CouncilStandUpCarl Tryggers foundation
Available from: 2017-03-17 Created: 2017-03-17 Last updated: 2017-11-29Bibliographically approved
Liu, Z., Li, H., Fan, C. & Luo, W. (2017). Necessary and sufficient elastic stability conditions in 21 quasicrystal Laue classes. European journal of mechanics. A, Solids, 65, 30-39
Open this publication in new window or tab >>Necessary and sufficient elastic stability conditions in 21 quasicrystal Laue classes
2017 (English)In: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 65, p. 30-39Article in journal (Refereed) Published
Abstract [en]

Mechanical stability is essential for solids and its stability criterion may date back to 75 years ago. Recently, the closed form necessary and sufficient conditions for elastic stability in all crystal classes have been investigated. Quasicrystals (QCs) are solids with long-range order and crystallographically forbidden rotational symmetries but without translational symmetry, attracting intense attentions in the last 30 years. In this work, we have explored the elastic constants and the elastic stability in detail for 1D, 2D and 3D QCs. All independent elastic constants and the closed form of necessary and sufficient conditions for elastic stability in all QCs classes are obtained, as a concise and pedagogical reference to stability criteria in aperiodic materials. Meanwhile, symmetry positions and stereographic projections of each QCs class are given as well.

Keywords
Elastic stability, Quasicrystals, Elastic constants, Stereograph
National Category
Reliability and Maintenance
Identifiers
urn:nbn:se:uu:diva-333066 (URN)10.1016/j.euromechsol.2017.02.007 (DOI)000405974300003 ()
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-09Bibliographically approved
Bouibes, A., Zaoui, A., Luo, W. & Ahuja, R. (2017). Promising optical characteristics of zinc peroxide from first-principles investigation. Solid State Communications, 263, 6-9
Open this publication in new window or tab >>Promising optical characteristics of zinc peroxide from first-principles investigation
2017 (English)In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 263, p. 6-9Article in journal (Refereed) Published
Abstract [en]

The structural, electronic and optical properties of zinc peroxide have been investigated using first principle pseudopotential method within generalized gradient approximation (GGA) proposed by Perdew-Burke-Ernzerhof (PBE) and also within Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional for the exchangecorrelation. An underestimated band gap (1.77 eV) along with the higher density of states and expanded energy bands around the Fermi level is obtained. The HSE06 approach corrects the band gap and allows a proper description of defects with energy levels close to the conduction band. According to the HSE06 calculations, the obtained band gap is 3.2 eV. This value is very close to semiconductors band gap such as TiO2 (3.1 eV). The dielectric constants are identified with respect to electronic band structure and are utilized to derive the other optical properties such as retractive index, energy loss function, reflectivity and absorption. This mainly shows that zinc peroxide is a poor absorber of visible light.

Keywords
ZnO2, DFT, Optical properties
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-335748 (URN)10.1016/j.ssc.2017.06.012 (DOI)000410842900002 ()
Available from: 2017-12-08 Created: 2017-12-08 Last updated: 2017-12-08Bibliographically approved
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