Rui Wang

Find an error

Name:

Organization: Chongqing University

Department: Institute for Structure and Function and Department of Physics

Title:

TOPICS

Polymer

Stimuli Responsive Polymers Stimuli Responsive Polymers Photo Responsive Polymers

Chemicals
References

Local charge states in hexagonal boron nitride with Stone–Wales defects

Co-reporter:Rui Wang, Jiali Yang, Xiaozhi Wu and Shaofeng Wang

Nanoscale 2016 vol. 8(Issue 15) pp:8210-8219

Publication Date(Web):16 Mar 2016

DOI:10.1039/C5NR09099G

A Stone–Wales (SW) defect is the simplest topological defect in graphene-like materials and can be potentially employed to design electronic devices . In this paper, we have systematically investigated the formation, structural, and electronic properties of the neutral and charged SW defects in hexagonal boron nitride (BN) using first-principles calculations. The transition states and energy barrier for the formation of SW defects demonstrate that the defected BN is stable. Our calculations show that there are two in-gap defect levels, which originate from the asymmetrical pentagon–heptagon pairs. The local defect configurations and electronic properties are sensitive to their charge states induced by the defect levels. The electronic band structures show that the negative and positive charged defects are mainly determined by shifting the conduction band minimum (CBM) and valence band maximum (VBM) respectively, and the SW-defected BN can realize −1 and +1 spin-polarized charge states. The effects of carbon (C) substitution on neutral and charged SW-defected BN have also been studied. Our results indicate that the C substitution of B in BN is in favour of the formation of SW defects. Structural and electronic calculations show rich charge-dependent properties of C substitutions in SW-defected BN, thus our theoretical study is important for various applications in the design of BN nanostructure-based devices.

Phase stability, mechanical properties and electronic structure of TiAl alloying with W, Mo, Sc and Yb: First-principles study

Co-reporter:Hai Hu, Xiaozhi Wu, Rui Wang, Weiguo Li, Qing Liu

Journal of Alloys and Compounds 2016 Volume 658() pp:689-696

Publication Date(Web):15 February 2016

DOI:10.1016/j.jallcom.2015.10.270

•There is a phase transition for TiAl from L10 to B2 structure when the concentrations of W and Mo are about 10.50 at.% and 11.50 at.%, respectively. However, there is no phase transition for L10 TiAl with Sc and Yb.•The brittle/ductile transition are predicted for TiAl with W, Mo, Sc and Yb. It is found that W and Mo can effectively improve the ductility of TiAl due to the phase transition.•The density of states is also used to analysis the mechanical properties, which is consistent with brittle/ductile transition map of TiAl based alloys.The phase stability and site preference of alloying elements W, Mo, Sc and Yb in L10 and B2 TiAl alloys were investigated using first-principles calculations. It is found that there will be a phase transition from L10 to B2 structure when the concentrations of W and Mo are about 10.50 at.% and 11.50 at.%, respectively. However, there is no phase transition for L10 TiAl with Sc and Yb. The elastic constants, bulk modulus, shear modulus, Poisson's ratio and hardness of TiAl alloys are also systematically presented. Based on Pugh ratio, the brittle/ductile transition are predicted for TiAl with W, Mo, Sc and Yb. It is found that W and Mo can effectively improve the ductility of TiAl due to the phase transition. Finally, the density of states is also used to analysis the mechanical properties, which is consistent with brittle/ductile transition map of TiAl based alloys.

Charge transfer of edge states in zigzag silicene nanoribbons with Stone–Wales defects from first-principles

Co-reporter:Xie Ting, Wang Rui, Wang Shaofeng, Wu Xiaozhi

Applied Surface Science 2016 Volume 383() pp:310-316

Publication Date(Web):15 October 2016

DOI:10.1016/j.apsusc.2016.04.172

Highlights

•: The properties of SW defects in silicene and ZSNRs are obtained.
•: The SW defects at the edge of ZSNRs induce a sizable gap.
•: The charge transfer of edge states is resulted from SW defects in ZSNRS.

Structural stability, mechanical properties and stacking fault energies of TiAl3 alloyed with Zn, Cu, Ag: First-principles study

Co-reporter:Hai Hu, Xiaozhi Wu, Rui Wang, Zhihong Jia, Weiguo Li, Qing Liu

Journal of Alloys and Compounds 2016 Volume 666() pp:185-196

Publication Date(Web):5 May 2016

DOI:10.1016/j.jallcom.2016.01.106

•There is a phase transition from D022 to L12 with Zn, Cu and Ag.•The ductility of TiAl3 are improved due to the phase transition.•The phase stability maybe weakened by the reduction of stacking fault energy.•Density of states are used to reveal mechanical properties of TiAl3.The structural stability of D022 TiAl3 alloyed with Zn, Cu and Ag are systematically investigated using first-principles calculations. There is a phase transition from D022 to L12 with the increasing of the concentrations of Zn, Cu and Ag, respectively. Based on the predicted elastic constants and Pugh's ratio, the ductility of TiAl3 are improved due to the phase transition. The generalized stacking fault energies and cleavage energies are also presented. The reduced unstable stacking fault energy and antiphase boundary energy of 〈110〉{001} slip systems may weaken the stability of D022 TiAl3. Furthermore, Rice and Zhou–Carlsson–Thomson criterions are used to reveal the brittle/ductile mechanism, which is in agreement with Pugh's view. Finally, the electronic properties are also presented. The DOS suggests that weakened p–d interactions between Al and Ti atoms but enhanced d–d interactions between Ti and alloying atoms in TiAl3 result in the improvement of ductility.

Temperature effects on the generalized planar fault energies and twinnabilities of Al, Ni and Cu: First principles calculations

Co-reporter:Lili Liu, Rui Wang, Xiaozhi Wu, Liyong Gan, Qunyi Wei

Computational Materials Science 2014 Volume 88() pp:124-130

Publication Date(Web):1 June 2014

DOI:10.1016/j.commatsci.2014.03.005

•Temperature effects on GPFE of Al, Ni and Cu are studied by first-principles methods.•Three typical twinnabilities at different temperature of Al, Ni and Cu are studied.•GPFE and twinnabilities of Al, Ni and Cu reduce with increasing temperature.Based on the quasiharmonic approach from first-principles phonon calculations, the volume versus temperature relations for Al, Ni and Cu are obtained. Using the equilibrium volumes at temperature T, the temperature dependences of generalized planar fault energies have also been calculated by first-principles calculations. It is found that the generalized planar fault energies reduce slightly with increasing temperature. Based on the calculated generalized planar fault energies, the twinnabilities of Al, Ni and Cu are discussed with the three typical criteria for crack tip twinning, grain boundary twinning and inherent twinning at different temperatures. The twinnabilities of Al, Ni and Cu also decrease slightly with increasing temperature. Ni and Cu have the inherent twinnabilities. But, Al does not exhibit inherent twinnability. These results are in agreement with the previous theoretical studies at 0 K and experimental observations at ambient temperature.

First-principles calculations on finite temperature elastic properties of B2-AlRE (RE = Y, Tb, Pr, Nd, Dy) intermetallics

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu

Intermetallics 2012 Volume 26() pp:57-61

Publication Date(Web):July 2012

DOI:10.1016/j.intermet.2012.02.021

We have investigated the finite temperature elastic properties of AlRE (RE = Y, Tb, Pr, Nd, Dy) with B2-type structures from first principles. The phonon free energy and thermal expansion are obtained from the quasiharmonic approach based on density-functional perturbation theory. The static volume-dependent elastic constants are obtained from energy–strain functions by using the first-principles total-energy method. The comparison between our predicted results and the ultrasonic experimental data for a benchmark material Al provides excellent agreements. At T = 0 K, our calculated values of lattice equilibrium volume and elastic moduli of our calculated AlRE (RE = Y, Tb, Pr, Nd, Dy) intermetallics agree well with the previous theoretical results. The temperature-dependent elastic constants exhibit a normal behavior with temperature, i.e., decrease and approach linearity at higher temperature and zero slope around zero temperature. Furthermore, the anisotropy ratio and sound velocities as a function of temperature have also been discussed.Highlights► The finite temperature elastic constants of AlRE are calculated from first principles. ► The quasiharmonic approach is used to calculate thermal expansion. ► We discuss that the anisotropy ratio as a function of temperature. ► The temperature-dependent sound velocities are investigated.

The third-order elastic moduli and pressure derivatives for AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics with B2-structure: A first-principles study

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu, Yin Yao

Solid State Communications 2011 Volume 151(14–15) pp:996-1000

Publication Date(Web):July–August 2011

DOI:10.1016/j.ssc.2011.04.030

The third-order elastic moduli and pressure derivatives of the second-order elastic constants of novel B2-type AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics are presented from first-principles calculations. The elastic moduli are obtained from the coefficients of the polynomials from the nonlinear least-squares fitting of the energy–strain functions. The calculated second-order elastic constants of AlRE intermetallics are consistent with the previous calculations. To judge that our computational accuracy is reasonable, the calculated third-order constants of Al are compared with the available experimental data and other theoretical results and are found to have good agreements. In comparison with the theory of the linear elasticity, the third-order effects are very important with the finite strains which are lager than approximately 3.5%. Finally, the pressure derivatives have been discussed.Highlights► The third-order elastic moduli of AlRE intermetallics are obtained from DFT calculations. ► The method of applying a series of finite strains has been employed. ► The range of the deformation has been discussed both for linear and nonlinear elasticity. ► The pressure derivatives of second-order elastic have also been calculated.

Nonlinear elasticity of monolayer zinc oxide honeycomb structures: A first-principles study

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu, Shaorong Li, Lili Liu

Physica E: Low-dimensional Systems and Nanostructures 2011 Volume 43(Issue 4) pp:914-918

Publication Date(Web):February 2011

DOI:10.1016/j.physe.2010.11.013

We present the second- and third-order elastic constants and discuss the nonlinear elasticity for monolayer zinc oxide (ZnO) with honeycomb structure. Density functional theory (DFT) within generalized-gradient-approximation (GGA) combining with the method of homogeneous deformation is employed. The predictions for the elastic constants are obtained from the nonlinear least-squares polynomial fit to the calculated strain-energy relations from first-principles total-energy calculations. In comparison with the linear approach, the nonlinear effects really matter for strain larger than approximately 3.0%. We discuss how internal relaxation acts on the elastic properties, and internal relaxation displacements for the corresponding applied strain are obtained. Our results show that internal relaxation is important for the values of elastic constants, and especially influence the third-order elastic constants. Finally, we discuss force–displacement behavior and the breaking strength of monolayer ZnO within a framework of nonlinear stress–strain relationship. Monolayer ZnO exhibits very high ductility, in our study exceeding 20% ductility in tension, and the elastic response will exhibit highly nonlinear while the third-order effects really matter.Research Highlights► Second- and third-order elastic constants of two-dimensional honeycomb structures of zinc oxide have been obtained by using First-principles calculations. ► The internal relaxation importantly influences on the nonlinear elastic properties. ► The nonlinear effects really matter for strain larger than approximately 3.0%. ► The nonlinear stress–strain relationship shows that monolayer ZnO exhibits very high ductility.

First-principles phonon calculations of thermodynamic properties for ductile rare-earth intermetallic compounds

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu, Anping Liu

Intermetallics 2011 Volume 19(Issue 10) pp:1599-1604

Publication Date(Web):October 2011

DOI:10.1016/j.intermet.2011.06.006

The thermodynamic properties of ductile rare-earth intermetallic compounds YAg and YCu with CsCl-type B2 structure have been studied by performing density-functional theory (DFT) and density-functional perturbation theory (DFPT). To judge that our computational method is reasonable, NiAl has also been investigated in comparisons with experimental data and previous theoretical results. Phonon dispersions and density of states are studied, and it is found that the density of states is mostly composed of Y states both in YAg and YCu at high frequencies. The temperature dependence of various quantities such as the thermal expansion, the isothermal bulk modulus, and the heat capacity is computed under the quasi-harmonic approximation (QHA), and the variation features of these quantities are discussed in detail. From these results, we demonstrate that the intermetallics with better ductility have larger thermal expansions.Highlights► The thermodynamic properties of YAg and YCu have been studied from first-principles phonon calculations.► Phonon dispersions for YAg and YCu have been obtained from DFPT. ► Phonon density of states for YAg and YCu is mostly composed of Y states at high frequencies. ► The intermetallics with better ductility have larger thermal expansions.

Generalized-stacking-fault energy and surface properties for HCP metals: A first-principles study

Co-reporter:Xiaozhi Wu, Rui Wang, Shaofeng Wang

Applied Surface Science 2010 Volume 256(Issue 11) pp:3409-3412

Publication Date(Web):15 March 2010

DOI:10.1016/j.apsusc.2009.12.042

Abstract

We present first-principles calculations on the generalized-stacking-fault (GSF) energies and surface properties for several HCP metals on Mg, Be, Ti, Zn, and Zr, employing density functional theory (DFT) within generalized-gradient-approximation (GGA) and spin-polarized GGA (SGGA) using the Vienna ab initio simulation package (VASP). Using a supercell approach, stacking fault energies for the [1 1 $\bar{2}$ 0] and [1 0 $\bar{1}$ 0] slip systems, and surface properties on basal plane (0 0 0 1) have been determined. Our results show that GSF energy is sensitive to the primitive cell volumes and the ratio c/a $c / a$ for HCP metals. A spin-polarized calculations should be considered for transition-metal Ti, Zn, and Zr. The results for Mg from this work are good with ones from the previous ab initio and the experiments.

Ab initio calculations of generalized-stacking-fault energy surfaces and surface energies for FCC metals

Co-reporter:Xiao-Zhi Wu, Rui Wang, Shao-Feng Wang, Qun-Yi Wei

Applied Surface Science 2010 Volume 256(Issue 21) pp:6345-6349

Publication Date(Web):15 August 2010

DOI:10.1016/j.apsusc.2010.04.014

Abstract

The ab initio calculations have been used to study the generalized-stacking-fault energy (GSFE) surfaces and surface energies for the closed-packed (1 1 1) plane in FCC metals Cu, Ag, Au, Ni, Al, Rh, Ir, Pd, Pt, and Pb. The GSFE curves along $〈 1 1 2 〉$ (1 1 1) direction and $〈 1 1 0 〉$ (1 1 1) direction, and surface energies have been calculated from first principles. Based on the translational symmetry of the GSFE surfaces, the fitted expressions have been obtained from the Fourier series. Our results of the GSFEs and surface energies agree better with experimental results. The metals Al, Pd, and Pt have low γ_us/γ_I $γ_{u s} / γ_{I}$ value, so full dislocation will be observed easily; while Cu, Ag, Au, and Ni have large γ_us/γ_I $γ_{u s} / γ_{I}$ value, so it is preferred to create partial dislocation. From the calculations of surface energies, it is confirmed that the VIII column elements Ni, Rh, Ir, Pd, and Pt have higher surface energies than other metals.

Ab initio calculations on the third-order elastic constants for selected B2–MgRE (RE = Y, Tb, Dy, Nd) intermetallics

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu, Yin Yao, Anping Liu

Intermetallics 2010 Volume 18(Issue 12) pp:2472-2476

Publication Date(Web):December 2010

DOI:10.1016/j.intermet.2010.08.039

Axial strain and twist-induced changes in the electronic structure of carbon nanotubes

Co-reporter:Shaofeng Wang, Rui Wang, Xiaozhi Wu, Huili Zhang, Ruiping Liu

Physica E: Low-dimensional Systems and Nanostructures 2010 Volume 42(Issue 9) pp:2250-2256

Publication Date(Web):July 2010

DOI:10.1016/j.physe.2010.04.029

Based on the tight-binding model of generalized honeycomb lattice on cylinder, the band structure changes induced by axial strain and twist are present for the signal-wall carbon nanotubes (SWCNTs). The deformation-modified hopping amplitudes are dominated by the metric tensor and the curvature tensor. The analytical relations of the energy bands and the band gaps to both armchair and zigzag tubes are obtained. For the chiral nanotubes, we have successfully investigated the deformation-induced changes in band structure of individual nanotubes of known chiral index. The results in our model, returning to the undeformed tubes, are in good agreement with the previous experiments and theories.

On third-order elastic constants for ductile rare-earth intermetallic compounds: A first-principles study

Co-reporter:Rui Wang, Shaofeng Wang, Xiaozhi Wu

Intermetallics 2010 Volume 18(Issue 8) pp:1653-1658

Publication Date(Web):August 2010

DOI:10.1016/j.intermet.2010.04.021

We present the unknown third-order constants of ductile rare-earth intermetallic compounds YAg and YCu with CsCl-type B2 structure. Density functional theory (DFT) within generalized-gradient-approximation (GGA) combining with the method of homogeneous deformation is employed. The predictions for the elastic constants are obtained from a polynomial fit to the calculated strain–energy relation from first-principles total-energy calculations. Calculated second-order elastic constants are consistent with the previous calculations and the experiments. The third-order effects really matter when the finite strains are larger than approximately 3.0%. The relation between the third-order elastic constants and pressure derivatives of the second-order elastic constants has also been discussed.