检索结果-南通市图书馆

first principle Study on the Rectification of Molecular Junctions Based on the Thiol-ended Oligosilane

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2015年第6期34卷 813-821页

作者： ZHANG Rong-Fang YANG E LI Yi LIN Li-Xiang LING Qi-Dana College of Materials Science & Engineering Fujian Normal University College of Chemistry Fuzhou University

The electron transport properties of various molecular junctions based on the thiol-ended oligosilane are investigated through density functional theory combined with non-equilibrium Green＇s function formalism. Our calculations show that oligosilanes doped by the phenyl and -C10H6 groups demonstrate better rectifying effect and their rectification ratios are up to 15.41 and 65.13 for their molecular junctions. The current-voltage （I-V） curves of all the Au/ modified oligosilane/Au systems in this work are illustrated by frontier molecular orbitals, transmission spectra and density of states under zero bias. And their rectifying behaviors are analyzed through transmission spectra.

关键词： first principle thiol-ended oligosilane rectification

first principle study of the electronic structure of hafnium-doped anatase TiO_2

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2012年第1期33卷 25-28页

作者：李乐中杨维清丁迎春朱兴华 Department of Optics and Electronics Chengdu University of Information Technology Chengdu 610225China

Crystal structures and electronic structures of hafnium doping anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on the density functional theory within the generalized gradient approximation. The calculated results show that the lattice parameters a and c of Hf-doped anatase TiO2 are larger than those of intrinsic TiO2 under the same calculated condition. The calculated band structure and density of states show that the conduction band width of Hf-doped TiO2 is broadened which results in the band gap of Hf-doped being smaller than the band gap of TiO2.

关键词： Hf-doped anatase TiO2 first principle crystal structure electronic structure

first principle calculation of elastic and thermodynamic properties of stishovite

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第12期19卷 425-430页

作者：刘勋周显明曾召益 Laboratory for Shockwave and Detonation Physics Institute of Fluid PhysicsChina Academy of Engineering Physics College of Physical Science and Technology Sichuan University

Using ab initio plane-wave pseudo-potential density functional theory method, the elastic constants and band structures of stishovite were calculated. The calculated elastic constants under ambient conditions agree well with previous experimental and theoretical data. C13, C33, C44, and C66 increase nearly linearly with pressure while C11 and C12 show irregularly changes with pressure over 20 GPa. The shear modulus （Cll-C12）/2 was observed to decrease drastically between 40 GPa and 50 GPa, indicating acoustic mode softening in consistency with the phase transition to CaC12-type structure around 50 GPa. The calculated band structures show no obvious difference at 0 and 80 GPa, being consistent with the high incompressibility of stishovite. With a quasi-harmonic Debye model, thermodynamic properties of stishovite were also calculated and the results are in good agreement with available experimental data.

关键词： first principle elastic constants thermal properties quasi-harmonic Debye model

Edge induced band bending in van der Waals heterojunctions:A first principle study

在线全文

学校读者我要写书评

暂无评论

Nano Research 2020年第3期13卷 701-708页

作者： Yang Ou Zhuo Kang Qingliang Liao Zheng Zhang Yue Zhang Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory for Advanced Energy Materials and TechnologiesUniversity of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials School of Materials Science and EngineeringUniversity cf Science and Technology BeijingBeijing 100083China

The dangling bond free nature of two-dimensional(2D)material surface/interface makes van der Waals(vdW)heterostructure attractive for novel electronic and optoelectronic applications.But in practice,edge is unavoidable and could cause band bending at 2D material edge analog to surface/interface band bending in conventional three-dimensional(3D)materials.Here,we report a first principle simulation on edge band bending of free standing MoS2/WS2 vdW heterojunction.Due to the imbalance charges at edge,S terminated edge causes upward band bending while Mo/W terminated induces downward bending in undoped case.The edge band bending is comparable to band gap and could obviously harm electronic and optoelectronic properties.We also investigate the edge band bending of electrostatic doped heterojunction.N doping raises the edge band whereas p doping causes a decline of edge band.Heavy n doping even reverses the downward edge band bending at Mo/W terminated edge.In contrast,heavy p doping doesn’t invert the upward bending to downward.Comparing with former experiments,the expected band gap narrowing introduced by interlayer potential gradient at edge is not observed in our free-standing structures and suggests substrate’s important role in this imbalance charge induced phenomenon.

关键词： edge band bending imbalance charge electrostatic doping transition metal dichalcogenides(TMDCs)van der Waals(vdW)heterojunction first principle

first-principle study of puckered arsenene MOSFET

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Semiconductors 2020年第8期41卷 75-80页

作者： Hengze Qu Ziwei Lin Ruijuan Guo Xiyu Ming Wenhan Zhou Shiying Guo Xiufeng Song Shengli Zhang Haibo Zeng Key Laboratory of Advanced Display Materials and Devices Ministry of Industry and Information TechnologyCollege of Material Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China

Two-dimensional material has been regarded as a competitive silicon-alternative with a gate length approaching sub-10 nm,due to its unique atomic thickness and outstanding electronic properties.Herein,we provide a comprehensively study on the electronic and ballistic transport properties of the puckered arsenene by the density functional theory coupled with nonequilibrium Green’s function formalism.The puckered arsenene exhibits an anisotropic characteristic,as effective mass for the electron/hole in the armchair and zigzag directions is 0.35/0.16 m0 and 1.26/0.32 m0.And it also holds a high electron mobility,as the highest value can reach 20045 cm2V–1s–1.Moreover,the puckered arsenene FETs with a 10-nm channel length possess high on/off ratio above 105 and a steep subthreshold swing below 75 mV/dec,which have the potential to design high-performance electronic devices.Interestingly,the channel length limit for arsenene FETs can reach 7-nm.Furthermore,the benchmarking of the intrinsic arsenene FETs and the 32-bit arithmetic logic unit circuits also shows that the devices possess high switching speed and low energy dissipation,which can be comparable to the CMOS technologies and other CMOS alternatives.Therefore,the puckered arsenene is an attractive channel material in next-generation electronics.

关键词： first principle two-dimensional material electronic properties arsenene MOSFET

Improved luminescence and photocatalytic properties of Sm^(3+)-doped ZnO nanoparticles via modified sol-gel route:A unified experimental and DFT+U approach

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2023年第4期41卷 550-560页

作者： Sikder Ashikuzzaman Ayon Sajjad Hasan Md Muktadir Billah Sadiq Shahriyar Nishat Alamgir Kabir Department of Materials and Metallurgical Engineering Bangladesh University of Engineering and TechnologyDhaka1000Bangladesh Department of Physics Bangladesh University of Engineering and TechnologyDhaka1000Bangladesh Department of Materials Science&Engineering Rensselaer Polytechnic Institute(RPI)NY12180USA Department of Physics University of DhakaDhaka1000Bangladesh

In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm^(3+)ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD)analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM).X-ray photoelectron spectroscopy(XPS)was carried out to confirm the prese nce of Sm~(3+)on the doped NPs.Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing abso rption in the visible range,and a minimum of 3.18 eV of optical bandgap for Zn_(0.97)Sm_(0.03)O is found.Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%,followed by an increase of Zn_(0.95)Sm_(0.05)O.Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra.Theoretical analysis was also carried out with density functional theory(DFT).This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully.Later,photocatalytic activity for the optimum composition,i.e.,3 mol%,was assessed experimentally.

关键词： Samarium XPS Recombination rate Photocatalytic first principle Defect state

first principles study of ceramic materials(IVB group carbides)under ultrafast laser irradiation

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第3期27卷 351-356页

作者：何南燐程新路张红闫改琴张佳 Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610065China Key Laboratory of High Energy Density Physics and Technology of Ministry of Education Sichuan UniversityChengdu 610065China College of Physical Science and Technology Sichuan UniversityChengdu 610065China

Group IVB carbides have been applied in extreme aerospace environments as hard ceramic coatings; ZrC is being considered as a replacement for SiC in nuclear reactors. Therefore, a thorough understanding of the laser irradiation response of group IVB carbides is of clear significance. However, the existing knowledge on the fundamental properties of IVB group carbides is limited and insufficient with regard to both irradiated and non-irradiated characteristics. We investigate the effect of ultrafast laser irradiation on the lattice stability of ceramic materials （IVB group carbides） using the density functional perturbation theory （DFPT）. The calculated phonon frequencies of TiC and ZrC at the ground state are in good agreement with previous calculations and experimental values. The phonon frequencies of IVB group carbides are positive, even though the electronic temperature reached 5 eV. Thus, IVB group carbides are more stable under ultrafast laser irradiation, which has greater benefits in nuclear and aeronautical applications compared to metals （W, Na）, semimetals （Bi）, and semiconductors （Si, SIC）. The thermodynamic properties of ZrC are calculated as functions of their lattice temperature at different electronic temperatures. The elastic shear constants of IVB group carbides satisfy the Born stability criteria at Te = 5 eV. In addition, a comparison of the predicted melting temperatures of IVB group carbides, reveal that HfC is better suited for extreme high-temperature environments.

关键词： first principle lattice stability elastic properties electronic excitation

A first-principles study on electronic structures and elastic properties of metal dopedα-Fe(N)high nitrogen steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2017年第1期24卷 103-110页

作者： Ji-chun Yang Xiang-jun Liu Gui-xiao Jia Xiao-yang Fu School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010Inner MongoliaChina

The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles method.The calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is disadvantageous.For Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping species.The obvious interaction exists among M3 d,Fe4s3p3d and N2 p.In these doping systems,metal atoms lose electrons,while N gains electrons.Dopings of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and Mg.Elastic calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are enhanced.The magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.

关键词： first principle High nitrogen steel Metal nitride Electronic structure Elastic property

Carrier transportation in polycrystalline CuInSe_2 thin films with Cu-deficient grain boundaries

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2015年第7期34卷 510-516页

作者： Bo Yin Chao-Gang Lou School of Electronic Science and Engineering Southeast University

The interface energies and electronic structures of(112) grain boundaries of Cu In Se2 thin films were investigated by first-principle calculations.It is found that the grain boundary with a Cu vacancy has low interface energy and exists widely in the films.The Cu deficiency may cause the charge imbalance and result in an upward band bending at the grain boundary.It also weakens the repulsion between Cu-3d orbital and Se-4p orbital and leads to the downward shift of valence band maximum.The two mechanisms,namely the band bending from the charge imbalance and the depression of the valence band maximum, have effects on the(112) grain boundaries with different defects.The change of band structure forms a potential barrier to prevent electrons or holes from approaching the grain boundary and reduces their recombination.This might be used to explain the effects of the grain boundary on carrier transportation and why polycrystalline Cu(In,Ga)Se2thin film solar cells have better performance than single-crystal cells.

关键词： first principle CuInSe2 Grain boundary Interface e