The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. ...The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly： the band gap widths and types （direct or indirect） of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.展开更多
This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical ch...This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical characteristics by using current-voltage （Ⅰ - Ⅴ） measurements. An electronic model with two back to back Sehottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured Ⅰ - Ⅴ characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.展开更多
GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nan...GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nanowires(NWs)is hindered by type-Ⅱquantum well structures arising from the mixture of zinc blende(ZB)and wurtzite(WZ)phases and surface defects due to the large surface-to-volume ratio.Achieving GaAs-based NWs with high emission efficiency has become a key research focus.In this study,pre-etched silicon substrates were combined with GaAs/AlGaAs core-shell heterostructure to achieve GaAs-based NWs with good perpendicularity,excellent crystal structures,and high emission efficiency by leveraging the shadowing effect and surface passivation.The primary evidence for this includes the prominent free-exciton emission in the variable-temperature spectra and the low thermal activation energy indicated by the variable-power spectra.The findings of this study suggest that the growth method described herein can be employed to enhance the crystal structure and optical properties of otherⅢ-Ⅴlow-dimensional materials,potentially paving the way for future NW devices.展开更多
Deep color glass-ceramics is prepared by using gold tailings as the main raw material, and Cr2O3 is added as nucleation agent. Influence of different Cr2O3 additions on crystallization structure and properties of CaO-...Deep color glass-ceramics is prepared by using gold tailings as the main raw material, and Cr2O3 is added as nucleation agent. Influence of different Cr2O3 additions on crystallization structure and properties of CaO-MgO-Al2O3-SiO2 glass-ceramics has been discussed so as to select optimum additions. DTA is employed to determine optimum crystallization and nucleation temperatures; XRD and SEM are used to characterize microstructure of each sample; and performance indexes, such as water absorption, bulk density, flexural strength and so on, are also determined. Experimental results show that when 3wt% Cr2O3 is introduced, fine glass-ceramics with diopside as the main crystal and Ca-Fe diopside as the second-crystal is obtained, and its corresponding performance indexes are as follows： water absorption 0.12%, bulk density 2.56 g/cm^3, and flexural strength 70.01 Mpa.展开更多
Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescen...Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescence,thermocatalysis,electrocatalysis,photocatalysis,magnetism,and optical activity.Over the past several decades,there has been tremendous progress in our understanding of the structure and physicochemical properties of Aun(SR)m NCs,resulting in the ability to fine-tune the characteristics of these materials.It is therefore helpful to examine the extent to which the properties of Aun(SR)m and related metal NCs can now be adjusted based on design.This review presents representative examples of previous studies concerning the geometry,electronic structure,luminescence properties,catalysis,magnetism and optical activity of Aun(SR)m and related metal NCs and discusses the current status of the designability of these NCs to impart specific structural and physicochemical characteristics.This information is expected to accelerate the fabrication of highly functional materials based on Aun(SR)m and related metal NCs.展开更多
The geometric, energetic, electronic structures and optical properties of ZnO nanowires （NWs） with hexagonal cross sections are investigated by using the first-principles calculation of plane wave ultra-soft pseudo-...The geometric, energetic, electronic structures and optical properties of ZnO nanowires （NWs） with hexagonal cross sections are investigated by using the first-principles calculation of plane wave ultra-soft pseudo-potential technology based on the density functional theory （DFT）. The calculated results reveal that the initial Zn-O double layers merge into single layers after structural relaxations, the band gap and binding energies decrease with the increase of the ZnO nanowire size. Those properties show great dimension and size dependence. It is also found that the dielectric functions of ZnO NWs have different peaks with respect to light polarization, and the peaks of ZnO NWs exhibit a significant blueshift in comparison with those of bulk ZnO. Our results gives some reference to the thorough understanding of optical properties of ZnO, and also enables more precise monitoring and controlling during the growth of ZnO materials to be possible.展开更多
The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te...The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te energetically prefers to substitute the core Ga（Ef = 0.4111 eV） under As-rich conditions of Ga As nanowires, while on surface, the single Te tends to substitute the surface As site. With increasing the Te concentration, the favorable substitution sites are 2Te–Ga–A and 3Te–Ga–D. Thus, the stability of the structure of the electronic structure and optical properties are discussed.展开更多
The 0.8 Me V copper （ Cu） ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires （Sn02 NWs） are investigated. The samples are irradiated at three differen...The 0.8 Me V copper （ Cu） ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires （Sn02 NWs） are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm2, 1 ×10^13 ions/cm2 and 5 × 10^13 ions/em2 at room temperature. The XRD analysis shows that the tetragonal phase of Sn02 NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTIR spectra of pristine Sn02 NWs exhibit the chemical composition of SnO2 while the Cn-O bond is also observed in the FTIR spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO2 is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code. Optical properties of SnO2 NWs are studied before and after Cu ion irradiation. Band gap analysis reveMs that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.展开更多
Carbon/carbon composites with higher mechanical strength and better reliability at elevated tempera-tures are urgently needed to satisfy the practical applications requirements.SiC nanowires(SiCNWs)modified C/C(SC-CC)...Carbon/carbon composites with higher mechanical strength and better reliability at elevated tempera-tures are urgently needed to satisfy the practical applications requirements.SiC nanowires(SiCNWs)modified C/C(SC-CC)composites have attracted an abundance of attention for their excellent mechanical performance.To further boost the mechanical strengths of composites and maximize the reinforcing efficiency of SiCNWs,we introduce orthogonally structured graphene nanosheets(OGNs)into SC-CC composites,in which OGNs are grafted on the SiCNWs via chemical vapor deposition(CVD)method,forming SC-G-CC composites.Benefiting from the nano-interface effects,uniform stress distribution,strong SiCNWs/PyC interfacial bonding and elevated stress propagation efficiency in the PyC matrix are achieved,thus SC-G-CC composites accomplish brilliant mechanical properties before and after 1,600℃ heat treatment.As temperature rises to 2,100℃,SiCNWs lose efficacy,whereas OGNs with excellent thermal stability continue to play the nano-interface role in the PyC matrix.Therefore,SC-G-CC com-posites show better mechanical performance after 2,100℃ heat treatment,and the mechanical strength retention rate(MSR)of interlaminar shear strength,out-of-plane and in-plane compressive strength of SC-G-CC composites reach 61.0%,55.7%and 55.3%,respectively.This work proposes an alternative thought for maximizing the potentiality of nanomaterials and edifies the mechanical modification of composites.展开更多
The geometries, electronic and magnetic properties of the trimetallic clusters FeA1Aun （n = 1-6） are systematically investigated using density functional theory （DFI＇）. A number of new isomers are obtained to pro...The geometries, electronic and magnetic properties of the trimetallic clusters FeA1Aun （n = 1-6） are systematically investigated using density functional theory （DFI＇）. A number of new isomers are obtained to probe the structural evolutions. All doped clusters show larger relative binding energies than pure Aun＋2 partners, indicating that doping with Fe and A1 atoms can stabilize the Aun clusters. The highest occupied molecular orbital-lowest unoccupied molecular orbital （HOMO- LUMO） gaps, vertical ionization potentials and vertical electron affinities are also studied and compared with those of pure gold clusters. Magnetism calculations demonstrate that the magnetic moments of FeA1Aun clusters each show a pronounced odd-even oscillation with the number of Au atoms.展开更多
Highly ordered Tb_(x)Fe_(7)Co_(3)(x=0,0.6,0.8)nanowires were synthesized in alumina templates by electrochemical deposition method.Here,the effects of Tb content and annealing treatment on the phase composition,morpho...Highly ordered Tb_(x)Fe_(7)Co_(3)(x=0,0.6,0.8)nanowires were synthesized in alumina templates by electrochemical deposition method.Here,the effects of Tb content and annealing treatment on the phase composition,morphology,crystalline structure and magnetic properties were investigated.The asdeposited Tb_0 Fe_(7)Co_(3)nanowires comprise Fe_(7)Co_(3)phase.While after adding Tb,the diffraction peaks slightly shift left,indicating the infiltration of Tb atoms into Fe_(7)Co_(3)phase.After annealing,Tb_0 Fe_(7)Co_(3)nanowires still consist of Fe_(7)Co_(3)phase with a slight enhancement on coercivity.While the annealed nanowires with Tb doped present a complex phase composition containing Fe3 Tb,Fe_(2)Tb,Co_(3)Tb,Co_(17)Tb_(2),TbFeO_(3)and Fe_(2)O_(3)phases distribute in the central portion,and Co_(0.72)Fe_(0.28)at the nanowire outer walls.The annealed Tb_(x)Fe_(7)Co_(3)(x=0.6,0.8)nanowires show higher magnetic performance owing to the formation of hard magnetic phases,the interfacial elastic coupling between hard and soft phases and the coherent Fe3 Tb/Co_(3)Tb interface which restrain the domain wall motion.To be specific,the coercivity and remanence ratio of TbxFe_(7)Co_(3)(x=0.6,0.8)nanowires significantly enhance with increasing Tb content.展开更多
The synthesis,structure and luminescent property of a tetranuclear gold（Ⅰ）complex with doubly bridging diethyldithiocarbamate（Et2dtc）and 1,1-bis（diphenylphosphino）ethene（（Ph2P）2C=CH2）are described.The compl...The synthesis,structure and luminescent property of a tetranuclear gold（Ⅰ）complex with doubly bridging diethyldithiocarbamate（Et2dtc）and 1,1-bis（diphenylphosphino）ethene（（Ph2P）2C=CH2）are described.The complex crystallizes in monoclinic space group C2/c with a=26.785（7）,b=25.654（6）,c=12.277（3）A,β=106.879（5）°,V=8073（4）A^3,Z=8,C31H32Au2F6NO3P2S2Sb,Mr=1222.32,Dc=2.011 g/cm^3,F（000）=4592,Rint=0.0529,T=293（2）K,μ=8.157 mm^（-1）,the final R=0.0464 and wR=0.1444 for 5804 observed reflections with I〉2σ（Ⅰ）.The intramolecular and intermolecular Au¨Au distances are 2.8670（9）and 3.2367（9）A,respectively.Weak emission appears at 517 nm at room temperature in the solid state.展开更多
Periodically ordered ZnO nanowire arrays were fabricated by a combination of soft templates created by electron beam lithography and an electrochemical process. Individual ZnO nanowires were precisely placed in desire...Periodically ordered ZnO nanowire arrays were fabricated by a combination of soft templates created by electron beam lithography and an electrochemical process. Individual ZnO nanowires were precisely placed in desired locations to form two-dimensional periodic structures with specific patterns. Scanning electron microscopy and light diffraction measurements confirmed the long-range ordered structures in the nanowire arrays. Variable temperature photoluminescence revealed both band edge and defect emissions. The obtained photonic structures may have potential applications in optical and optoelectronic devices.展开更多
The mechanical property and deformation mechanism of twinned gold nanowire with non-uniform distribution of twinned boundaries(TBs)are studied by the molecular dynamics(MD)method.It is found that the twin boundary spa...The mechanical property and deformation mechanism of twinned gold nanowire with non-uniform distribution of twinned boundaries(TBs)are studied by the molecular dynamics(MD)method.It is found that the twin boundary spacing(TBS)has a great effect on the strength and plasticity of the nanowires with uniform distribution of TBs.And the strength enhances with the decrease of TBS,while its plasticity declines.For the nanowires with non-uniform distribution of TBs,the differences in distribution among different TBSs have little effect on the Young's modulus or strength,and the compromise in strength appears.But the differences have a remarkable effect on the plasticity of twinned gold nanowire.The twinned gold nanowire with higher local symmetry ratio has better plasticity.The initial dislocations always form in the largest TBS and the fracture always appears at or near the twin boundaries adjacent to the smallest TBS.Some simulation results are consistent with the experimental results.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11004142the Program for New Century Excellent Talents in University under Grant No 11-035the Project Sponsored by the Scientific Research Foundation for ROCS of the Ministry of Education of China
文摘The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly： the band gap widths and types （direct or indirect） of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.
基金Project supported by the National Natural Science Foundation of China (Grant No 50575113)Program for NCET
文摘This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical characteristics by using current-voltage （Ⅰ - Ⅴ） measurements. An electronic model with two back to back Sehottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured Ⅰ - Ⅴ characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.
文摘GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nanowires(NWs)is hindered by type-Ⅱquantum well structures arising from the mixture of zinc blende(ZB)and wurtzite(WZ)phases and surface defects due to the large surface-to-volume ratio.Achieving GaAs-based NWs with high emission efficiency has become a key research focus.In this study,pre-etched silicon substrates were combined with GaAs/AlGaAs core-shell heterostructure to achieve GaAs-based NWs with good perpendicularity,excellent crystal structures,and high emission efficiency by leveraging the shadowing effect and surface passivation.The primary evidence for this includes the prominent free-exciton emission in the variable-temperature spectra and the low thermal activation energy indicated by the variable-power spectra.The findings of this study suggest that the growth method described herein can be employed to enhance the crystal structure and optical properties of otherⅢ-Ⅴlow-dimensional materials,potentially paving the way for future NW devices.
文摘Deep color glass-ceramics is prepared by using gold tailings as the main raw material, and Cr2O3 is added as nucleation agent. Influence of different Cr2O3 additions on crystallization structure and properties of CaO-MgO-Al2O3-SiO2 glass-ceramics has been discussed so as to select optimum additions. DTA is employed to determine optimum crystallization and nucleation temperatures; XRD and SEM are used to characterize microstructure of each sample; and performance indexes, such as water absorption, bulk density, flexural strength and so on, are also determined. Experimental results show that when 3wt% Cr2O3 is introduced, fine glass-ceramics with diopside as the main crystal and Ca-Fe diopside as the second-crystal is obtained, and its corresponding performance indexes are as follows： water absorption 0.12%, bulk density 2.56 g/cm^3, and flexural strength 70.01 Mpa.
基金Japan Society for the Promotion of Science,Grant/Award Numbers:20H02698,20H02552,18H05178,20H05115Hydrogenomics,Grant/Award Number:21H00027+7 种基金Aquatic Functional Materials,Grant/Award Numbers:18H05178,22H04562Yazaki Memorial Foundation for Science and TechnologyOgasawara Foundation for the Promotion of Science and EngineeringKao Foundation for Arts and SciencesTEPCO Memorial FoundationJapan Science SocietyTakahashi Industrial and Economic Research FoundationKubota Corporation。
文摘Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescence,thermocatalysis,electrocatalysis,photocatalysis,magnetism,and optical activity.Over the past several decades,there has been tremendous progress in our understanding of the structure and physicochemical properties of Aun(SR)m NCs,resulting in the ability to fine-tune the characteristics of these materials.It is therefore helpful to examine the extent to which the properties of Aun(SR)m and related metal NCs can now be adjusted based on design.This review presents representative examples of previous studies concerning the geometry,electronic structure,luminescence properties,catalysis,magnetism and optical activity of Aun(SR)m and related metal NCs and discusses the current status of the designability of these NCs to impart specific structural and physicochemical characteristics.This information is expected to accelerate the fabrication of highly functional materials based on Aun(SR)m and related metal NCs.
基金Project supported by the Natural Science Foundation of Shaanxi Province of China (Grant No 2005F39) the Special Foundation of the Education Department of Shaanxi Province (Grant No 08jk487).
文摘The geometric, energetic, electronic structures and optical properties of ZnO nanowires （NWs） with hexagonal cross sections are investigated by using the first-principles calculation of plane wave ultra-soft pseudo-potential technology based on the density functional theory （DFT）. The calculated results reveal that the initial Zn-O double layers merge into single layers after structural relaxations, the band gap and binding energies decrease with the increase of the ZnO nanowire size. Those properties show great dimension and size dependence. It is also found that the dielectric functions of ZnO NWs have different peaks with respect to light polarization, and the peaks of ZnO NWs exhibit a significant blueshift in comparison with those of bulk ZnO. Our results gives some reference to the thorough understanding of optical properties of ZnO, and also enables more precise monitoring and controlling during the growth of ZnO materials to be possible.
基金supported by the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,China,No.2012LF1003)the Research Foundation of Education Bureau of Sichuan Province(No.16ZA0316)
文摘The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te energetically prefers to substitute the core Ga（Ef = 0.4111 eV） under As-rich conditions of Ga As nanowires, while on surface, the single Te tends to substitute the surface As site. With increasing the Te concentration, the favorable substitution sites are 2Te–Ga–A and 3Te–Ga–D. Thus, the stability of the structure of the electronic structure and optical properties are discussed.
基金Supported by the Department of Physics,the University of AJKHigh Tech.Centralized Instrumentation Lab,the University of AJK,Pakistanthe Experimental Physics Division,and the National Center for Physics,Islamabad Pakistan
文摘The 0.8 Me V copper （ Cu） ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires （Sn02 NWs） are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm2, 1 ×10^13 ions/cm2 and 5 × 10^13 ions/em2 at room temperature. The XRD analysis shows that the tetragonal phase of Sn02 NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTIR spectra of pristine Sn02 NWs exhibit the chemical composition of SnO2 while the Cn-O bond is also observed in the FTIR spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO2 is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code. Optical properties of SnO2 NWs are studied before and after Cu ion irradiation. Band gap analysis reveMs that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.
基金supported by the National Natural Science Foundation of China(Grant No.52222204)the Joint Funds of the National Natural Science Foundation of China(Grant No.U21B2067)+2 种基金the Key R&D Program of Shaanxi Province(Grant Nos.2019ZDLGY04-02 and 2021ZDLGY14-04)Natural Science Basic Research Plan in Shaanxi(2022JC-25)GuangDong Basic and Applied Basic Research Foundation(2022A1515111220).
文摘Carbon/carbon composites with higher mechanical strength and better reliability at elevated tempera-tures are urgently needed to satisfy the practical applications requirements.SiC nanowires(SiCNWs)modified C/C(SC-CC)composites have attracted an abundance of attention for their excellent mechanical performance.To further boost the mechanical strengths of composites and maximize the reinforcing efficiency of SiCNWs,we introduce orthogonally structured graphene nanosheets(OGNs)into SC-CC composites,in which OGNs are grafted on the SiCNWs via chemical vapor deposition(CVD)method,forming SC-G-CC composites.Benefiting from the nano-interface effects,uniform stress distribution,strong SiCNWs/PyC interfacial bonding and elevated stress propagation efficiency in the PyC matrix are achieved,thus SC-G-CC composites accomplish brilliant mechanical properties before and after 1,600℃ heat treatment.As temperature rises to 2,100℃,SiCNWs lose efficacy,whereas OGNs with excellent thermal stability continue to play the nano-interface role in the PyC matrix.Therefore,SC-G-CC com-posites show better mechanical performance after 2,100℃ heat treatment,and the mechanical strength retention rate(MSR)of interlaminar shear strength,out-of-plane and in-plane compressive strength of SC-G-CC composites reach 61.0%,55.7%and 55.3%,respectively.This work proposes an alternative thought for maximizing the potentiality of nanomaterials and edifies the mechanical modification of composites.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204079,11304096,and 11404333)the Natural Science Foundation of Shanghai,China(Grant No.12ZR1407000)
文摘The geometries, electronic and magnetic properties of the trimetallic clusters FeA1Aun （n = 1-6） are systematically investigated using density functional theory （DFI＇）. A number of new isomers are obtained to probe the structural evolutions. All doped clusters show larger relative binding energies than pure Aun＋2 partners, indicating that doping with Fe and A1 atoms can stabilize the Aun clusters. The highest occupied molecular orbital-lowest unoccupied molecular orbital （HOMO- LUMO） gaps, vertical ionization potentials and vertical electron affinities are also studied and compared with those of pure gold clusters. Magnetism calculations demonstrate that the magnetic moments of FeA1Aun clusters each show a pronounced odd-even oscillation with the number of Au atoms.
基金Project supported by National Natural Science Foundation of China(51271070,51871087)the Natural Science Foundation of Hebei Province(E2016202406)。
文摘Highly ordered Tb_(x)Fe_(7)Co_(3)(x=0,0.6,0.8)nanowires were synthesized in alumina templates by electrochemical deposition method.Here,the effects of Tb content and annealing treatment on the phase composition,morphology,crystalline structure and magnetic properties were investigated.The asdeposited Tb_0 Fe_(7)Co_(3)nanowires comprise Fe_(7)Co_(3)phase.While after adding Tb,the diffraction peaks slightly shift left,indicating the infiltration of Tb atoms into Fe_(7)Co_(3)phase.After annealing,Tb_0 Fe_(7)Co_(3)nanowires still consist of Fe_(7)Co_(3)phase with a slight enhancement on coercivity.While the annealed nanowires with Tb doped present a complex phase composition containing Fe3 Tb,Fe_(2)Tb,Co_(3)Tb,Co_(17)Tb_(2),TbFeO_(3)and Fe_(2)O_(3)phases distribute in the central portion,and Co_(0.72)Fe_(0.28)at the nanowire outer walls.The annealed Tb_(x)Fe_(7)Co_(3)(x=0.6,0.8)nanowires show higher magnetic performance owing to the formation of hard magnetic phases,the interfacial elastic coupling between hard and soft phases and the coherent Fe3 Tb/Co_(3)Tb interface which restrain the domain wall motion.To be specific,the coercivity and remanence ratio of TbxFe_(7)Co_(3)(x=0.6,0.8)nanowires significantly enhance with increasing Tb content.
基金financial supports from the NNSFC(20931006,U0934003,and 91122006)the NSF of Fujian Province(2011J01065)
文摘The synthesis,structure and luminescent property of a tetranuclear gold（Ⅰ）complex with doubly bridging diethyldithiocarbamate（Et2dtc）and 1,1-bis（diphenylphosphino）ethene（（Ph2P）2C=CH2）are described.The complex crystallizes in monoclinic space group C2/c with a=26.785（7）,b=25.654（6）,c=12.277（3）A,β=106.879（5）°,V=8073（4）A^3,Z=8,C31H32Au2F6NO3P2S2Sb,Mr=1222.32,Dc=2.011 g/cm^3,F（000）=4592,Rint=0.0529,T=293（2）K,μ=8.157 mm^（-1）,the final R=0.0464 and wR=0.1444 for 5804 observed reflections with I〉2σ（Ⅰ）.The intramolecular and intermolecular Au¨Au distances are 2.8670（9）and 3.2367（9）A,respectively.Weak emission appears at 517 nm at room temperature in the solid state.
文摘Periodically ordered ZnO nanowire arrays were fabricated by a combination of soft templates created by electron beam lithography and an electrochemical process. Individual ZnO nanowires were precisely placed in desired locations to form two-dimensional periodic structures with specific patterns. Scanning electron microscopy and light diffraction measurements confirmed the long-range ordered structures in the nanowire arrays. Variable temperature photoluminescence revealed both band edge and defect emissions. The obtained photonic structures may have potential applications in optical and optoelectronic devices.
基金the National Natural Science Foundation of China(Grant No.51771033).
文摘The mechanical property and deformation mechanism of twinned gold nanowire with non-uniform distribution of twinned boundaries(TBs)are studied by the molecular dynamics(MD)method.It is found that the twin boundary spacing(TBS)has a great effect on the strength and plasticity of the nanowires with uniform distribution of TBs.And the strength enhances with the decrease of TBS,while its plasticity declines.For the nanowires with non-uniform distribution of TBs,the differences in distribution among different TBSs have little effect on the Young's modulus or strength,and the compromise in strength appears.But the differences have a remarkable effect on the plasticity of twinned gold nanowire.The twinned gold nanowire with higher local symmetry ratio has better plasticity.The initial dislocations always form in the largest TBS and the fracture always appears at or near the twin boundaries adjacent to the smallest TBS.Some simulation results are consistent with the experimental results.
