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Wang B.,Yancheng Institute of Technology | Wang X.,Huaiyin Teachers College | Zhao J.,Key Laboratory of Materials Modification by Laser | Zhao J.,Dalian University of Technology
Journal of Physical Chemistry C | Year: 2010

Very recently, mass spectroscopy of ZnO clusters revealed a hitherto unknown (ZnO)60 magic-number cluster with exceptional stability. Using first-principles approaches, we searched the most stable structures of medium-size (ZnO)n clusters by considering several possible structural motifs. Instead of the previously nominated nested cage for (ZnO)60, we found a sodalite structure via coalescence of (ZnO) 12 cages, which was predicted to be a metastable phase in bulk ZnO solid. Due to the smaller influence of surface reconstruction, this sodalite motif is very competitive for larger (ZnO)n clusters up to n = 96. © 2010 American Chemical Society.


Ding W.,Dalian Jiaotong University | Ding W.,Key Laboratory of Materials Modification by Laser | Ju D.,Saitama Institute of Technology | Chai W.,Dalian Jiaotong University
Applied Surface Science | Year: 2010

Polyethylene terephthalate (PET) surface was bombarded by N ion beams at room temperature. Varying the working pressure of the ion beams, PET surfaces with different composition and properties were obtained. Characterization by X-ray photoelectron spectrometry showed that only on film surface, ester bonds, especially C-O bonds, were broken and N element chemical bonded with C. The influence depth was less than 5 nm because of the lower ion energy (about 103 eV). Contact angle results revealed that with increasing the working pressure of ion beams, the contact angle of PET surface to pure water increased from 51° to 130°. With these results, one conclusion could be deduced that the hydrophilic and hydrophobic properties of PET surface could be influenced by N atom chemical bond with C, which in turn is controlled by the working pressure of N ion beams. © 2010 Elsevier B.V.


Du Y.,University of Wollongong | Zhuang J.,University of Wollongong | Liu H.,Key Laboratory of Materials Modification by Laser | Xu X.,University of Wollongong | And 9 more authors.
ACS Nano | Year: 2014

Silicene monolayers grown on Ag(111) surfaces demonstrate a band gap that is tunable by oxygen adatoms from semimetallic to semiconducting type. With the use of low-temperature scanning tunneling microscopy, we find that the adsorption configurations and amounts of oxygen adatoms on the silicene surface are critical for band gap engineering, which is dominated by different buckled structures in √13 × √13, 4 × 4, and 2√3 × 2√3 silicene layers. The Si-O-Si bonds are the most energy-favored species formed on √13 × √13, 4 × 4, and 2√3 × 2√3 structures under oxidation, which is verified by in situ Raman spectroscopy as well as first-principles calculations. The silicene monolayers retain their structures when fully covered by oxygen adatoms. Our work demonstrates the feasibility of tuning the band gap of silicene with oxygen adatoms, which, in turn, expands the base of available two-dimensional electronic materials for devices with properties that is hardly achieved with graphene oxide. © 2014 American Chemical Society.


Ma J.L.,Dalian University of Technology | Ye F.,Dalian University of Technology | Ye F.,Key Laboratory of Materials Modification by Laser | Ou D.R.,CAS Dalian Institute of Chemical Physics | And 2 more authors.
Journal of Physical Chemistry C | Year: 2012

Defect clusters containing oxygen vacancies and Ce3+ cations on ceria (CeO2) surface dominate the electronic and chemical properties of the surface. However, the structures of the clusters, especially the arrangements of the oxygen vacancies in the clusters, have not been explained consistently. In this work, atomistic simulation based on energy minimization has been used to investigate the cluster structures on ceria {111} surface. It was found out that the oxygen vacancies are energetically favorable to be at the second-neighbor sites to their associated Ce3+ cations. Moreover, the subsurface oxygen vacancies on the third layer are essential for the arrangement of the surface oxygen vacancy clusters. Due to the existence of the subsurface oxygen vacancies, the adjacent surface oxygen vacancies tend to be separated by 〈110〉/2, and the linear surface clusters are more energetically favorable than the triangle ones. Then, the structure development with cluster size is discussed. © 2012 American Chemical Society.


Cao S.P.,Dalian University of Technology | Ye F.,Dalian University of Technology | Ye F.,Key Laboratory of Materials Modification by Laser | Hou B.,Dalian University of Technology | Xu A.Y.,Dalian University of Technology
Thin Solid Films | Year: 2013

Aluminum-doped zinc oxide films were prepared using electron beam evaporation method at a series of oblique angles.It has been found out that the columnar structure in the films inclined with oblique angle.Moreover, the angle between the growth direction of the columnar structure and the substrate normal was essentially the same as the oblique angle.The film thickness, the average transmittance, the normalized absorption and the sheet resistance also varied as a function of angle.These properties also gradually varied along the film's surface.Then, the effects of oblique angle deposition on the film properties were discussed based on deposition speed and shadowing effect.© 2013 Elsevier B.V.All rights reserved.


Han Y.,Nanjing University | Ge G.-X.,Nanjing University | Wan J.-G.,Nanjing University | Zhao J.-J.,Key Laboratory of Materials Modification by Laser | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We predict that a combined system of Ir dimer situated on the single-vacancy (SV) graphene is extremely stable and has high magnetic anisotropy energy (MAE), promising to be a potential candidate for high density magnetic storage. Our theoretical results show that high energy gradient in the SV graphene makes it possible to move the Ir dimer from the perfect graphene area into the center of SV (CSV), leading to the formation of the highly stable system with the Ir-Ir bond axis exactly perpendicular to the graphene plane. The calculated MAE value is as large as 25.7 meV per Ir atom. The origin of giant MAE in such a system is attributed to the difference of local densities of electronic states magnetized along different directions caused by special symmetry of Ir2 at CSV. We also propose a feasible avenue to assemble the Ir dimers on the graphene with the pattern of SV defects for actual applications. © 2013 American Physical Society.


Huang S.,Key Laboratory of Materials Modification by Laser | Xu Q.,Kyoto University | Yoshiiie T.,Kyoto University
Materials Letters | Year: 2016

The effects of Cr and W solute atoms on the evolution of irradiation-induced defects in Fe-8Cr and Fe-8Cr-2W alloys upon annealing after low-temperature neutron and electron irradiation were investigated by using positron annihilation lifetime measurements. Vacancy defects behavior at elevated temperatures showed that added solute Cr and W in Fe clearly suppress void growth. The void swelling suppression by Cr was explained using configuration-trapping model. For the W solute effects, the results of two types of irradiation support the solute and dislocation interaction model. Related results are important for the fabrication of improved radiation-resistant materials for fission or fusion reactors. © 2016 Elsevier B.V.


Wang S.-X.,Key Laboratory of Materials Modification by Laser | Wang S.-X.,Dalian Jiaotong University | Quan S.-G.,Key Laboratory of Materials Modification by Laser | Dong C.,Key Laboratory of Materials Modification by Laser
Thermochimica Acta | Year: 2012

The kinetics of the glass transition of Zr 57.2Al 21.4Ni 21.4 bulk metallic glass (BMG) was studied using differential scanning calorimetry (DSC) with continuous heating of the sample at various heating rates. The heating rate dependence of the glass transition temperature (T g) was investigated. By employing Moynihan and Kissinger models, the activation energy (E) of the glass transition was determined. It was shown that the transition process cannot be described in terms of single activation energy. The variation of E with the extent of conversion (α) was further analyzed by using two isoconversional methods (Kissinger-Akahira-Sunose method and Vyazovkin method). Evidence of the variation of E throughout the glass transition region was observed, which indicated that the transformation from amorphous to a supercooled liquid phase of Zr 57.2Al 21.4Ni 21.4 BMG was a complex process. © 2011 Elsevier B.V. All rights reserved.


Liu X.,Key Laboratory of Materials Modification by Laser | Mei X.,Key Laboratory of Materials Modification by Laser | Qiang J.,Key Laboratory of Materials Modification by Laser | Remnev G.E.,Tomsk Polytechnic University | Wang Y.,Key Laboratory of Materials Modification by Laser
Applied Surface Science | Year: 2014

High intensity pulsed ion beam technology was used for the surface irradiation treatment of metallic glass Zr55Al10Cu 30Ni5 and W metal. The ion beam was mainly composed of Cn+ (70%) and H+ (30%) at an acceleration voltage of 250 kV under different energy densities for different number of pulses. XRD analysis showed that the metallic glass remained amorphous in its main structure after HIPIB irradiation, without apparent presence of crystalline phases. SEM analysis concluded that there was no apparent irradiation damage on the surface of metallic glass at the low irradiation frequency (3 times and 10 times); "petal"-shaped irradiation damage appeared on the surface of metallic glass after multi-irradiation (100 times and 300 times), and the composition of the petal center included Fe and Cr, the composition of an ion diode cathode, in addition to the composition of Zr-based metallic glass. TEM analysis of irradiated metallic glass showed that a small amount of nanocrystalline Zr 2Ni-type phase (face centered cubic) was produced only at 300-time irradiation. Cracks appeared on the surface of W after 100-time and 300-time irradiation; shedding phenomenon even appeared on the surface of W at the energy densities of 1.4 J/cm2 and 2.0 J/cm2. The surface nano-hardness of irradiated metallic glass decreased. © 2014 Elsevier B.V. All rights reserved.


Jiang X.,Key Laboratory of Materials Modification by Laser | Hao B.,Key Laboratory of Materials Modification by Laser
Journal of Crystal Growth | Year: 2010

Gd2O3-doped CeO2 (Gd0.1Ce0.9O1.95, GDC) thin films were synthesized on (1 0 0) Si single crystal substrates by a reactive radio frequency magnetron sputtering technique. Structures and surface morphologies were characterized by X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and one-dimensional power spectral density (1DPSD) analysis. The XRD patterns indicated that, in the temperature range of 200-700 °C, f.c.c. structured GDC thin films were formed with growth orientations varying with temperature-random growth at 200 °C, (2 2 0) textures at 300-600 °C and (1 1 1) texture at 700 °C. GDC film synthesized at 200 °C had the smoothest surface with roughness of Rrms=0.973 nm. Its 1DPSD plot was characterized with a constant part at the low frequencies and a part at the high frequencies that could be fitted by the f-2.4 power law decay. Such surface feature and scaling behavior were probably caused by the high deposition rate and random growth in the GDC film at this temperature. At higher temperatures (300-700 °C), however, an intermediate frequency slope (-γ2≈-2) appeared in the 1DPSD plots between the low frequency constant part and the high frequency part fitted by f-4 power law decay, which indicated a roughing mechanism dominated by crystallographic orientation growth that caused much rougher surfaces in GDC films (Rrms>4 nm). © 2010 Elsevier B.V. All rights reserved.

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