Photoelectrochemical water oxidation reaction (PEC-WOR) as a sustainable route to produce H_(2)O_(2) is attractive but limited by low activity and poor product selectivity of photoanodes due to limited photogenerated ...Photoelectrochemical water oxidation reaction (PEC-WOR) as a sustainable route to produce H_(2)O_(2) is attractive but limited by low activity and poor product selectivity of photoanodes due to limited photogenerated charge efficiency and unfavorable thermodynamics. Herein, by crystal orientation engineering, the WO_(3) photoanode exposing (200) facets achieves both superior WOR activity (15.4 mA cm^(−2) at 1.76 VRHE) and high selectivity to H_(2)O_(2) (∼70%). Comprehensive experimental and theoretical investigations discover that the high PEC-WOR activity of WO_(3)-(200) is attributed to the rapid photogenerated charge separation/transfer both in bulk and at interfaces of WO_(3)-(200) facet, which reduces the charge transfer resistance. This, coupling with the unique defective hydrogen bonding network at the WO_(3)-(200)/electrolyte interface evidenced by operando PEC Fourier transform infrared spectroscopy, facilitating the outward-transfer of the WOR-produced H^(+), lowers the overall reaction barrier for the PEC-WOR. The superior selectivity of PEC-WOR to H_(2)O_(2) is ascribed to the unique defective hydrogen bonding network alleviated adsorption of ∗OH over the WO_(3)-(200) facet, which specially lowers the energy barrier of the 2-electron pathway, as compared to the 4-electron pathway. This work addresses the significant role of crystal orientation engineering on photoelectrocatalytic activity and selectivity, and sheds lights on the underlying PEC mechanism by understanding the water adsorption behaviors under illumination. The knowledge gained is expected to be extended to other photoeletrochemical reactions.展开更多
To increase efficiency and improve performance, reducing cost and emissions, advanced single crystal Ni-based superalloys are required in aerospace propulsion and power generating gas turbines. With the development of...To increase efficiency and improve performance, reducing cost and emissions, advanced single crystal Ni-based superalloys are required in aerospace propulsion and power generating gas turbines. With the development of alloy, significant improvements in casting techniques have been achieved by introducing the directionally solidified （DS） casting process followed by single crystal （SX） technique. The deviation of preferred orientation of single crystal superalloys is one of the most important defects in casting. In directional solidification equipment with high temperature gradient, single crystal specimens of DZ417G alloy were prepared successfully by the modified Bridgeman method with spiral grain selector. The orientation was investigated by means of X-ray diffraction （XRD） and electron backscattered diffraction （EBSD）.The results show that the crystal selector with a smaller angle can effectively reduce the deviation of preferred orientation.展开更多
Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate ...Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate microscopic deformation structures of the single-crystal tungsten nanowires with different crystal orientations of 〈100〉, 〈110〉and 〈111〉, in order to reveal the effect of crystal orientation on their tensile mechanical properties and failure mechanisms. Research results show that all of the stress-strain curves are classified into four stages： elastic stage, damage stage, yielding stage and failure stage, where 〈100〉orientation has a special hardening stage after yielding and two descending stages. The crystal orientation has little effect on elastic modulus but great effect on tensile strength, yielding strength and ductility, depending on different atomic surface energies and principal sliding planes. The calculated values of elastic modulus are in good agreement with the tested values of elastic modulus.展开更多
The effect of the crystal orientations and precipitates on the corrosion behavior of Al-Cu-Li single crystals was studied by scanning electron microscopy, transmission electron microscopy, optical microscopy, immersio...The effect of the crystal orientations and precipitates on the corrosion behavior of Al-Cu-Li single crystals was studied by scanning electron microscopy, transmission electron microscopy, optical microscopy, immersion testing in exfoliation corrosion solution, and electrochemical testing. The results show that the corrosion rates of different orientations of the aged Al-Cu-Li alloy increase in the order of (001) 1 phase deteriorated the corrosion resistance of the Al-Cu-Li alloy, and the degree of deterioration differed in different crystal plane orientations. The severe localized corrosion of the aged alloy propagates along the crystallography and extends along the {111}Alplane in the form of corrosion bands.展开更多
A nickel-based superalloy was deposited onto a single crystal substrate based on epitaxial laser metal forming （E-LMF）. The microstructure development in two depositions has been researched. For the first time, the ...A nickel-based superalloy was deposited onto a single crystal substrate based on epitaxial laser metal forming （E-LMF）. The microstructure development in two depositions has been researched. For the first time, the crystal orientation of dendrites varying beyond 20° was found when the dendrites deflected in deposition. In addition, a new grain boundary was found between different orientation dendrites in a grain, and the detected grain boundary angle was 23°. The result shows that flowing field in laser pool is responsible for this phenomenon.展开更多
Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Result...Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Results reveal that Mg-4 wt% Zn alloy with dendritic microstructure exhibits typical { 0002} basal texture along growth direction. Based on this, the effect of grain orientation on corrosion behavior of directionally solidified Mg-4 wt% Zn alloy in 0.9 wt% NaCl solution was investigated. Result shows that {0002} oriented planes have better corrosion resistance than {1120} and {1010 } ones, which is attributed to a synergistic effect of surface energy, atomic packing density and the stability of oxidation film,2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology,展开更多
A novel approach to identify the crystal orientation of turbine blades with anisotropy materials is proposed. Based on enhanced mode basis, with the main advantages of its efficiency,accuracy and general applicability...A novel approach to identify the crystal orientation of turbine blades with anisotropy materials is proposed. Based on enhanced mode basis, with the main advantages of its efficiency,accuracy and general applicability, the blade vibration mode of each order is linearly constructed by several specified mode shapes, which are obtained from the considered turbine blade with specified crystal orientations correspondingly. Then, a surrogate model based on Kriging method is introduced for constructing the condensed perturbed matrix of stiffness in order to improve the efficiency even further. The constructed surrogate model allows to perform the modal analysis of turbine blades with arbitrary crystal orientations in higher efficiency, due to the fact that the elements of condensed perturbed matrix of stiffness are considered in construction of the surrogate model rather than concerning the perturbation of all the elements of the initial stiffness matrix for the blade. Genetic algorithm is finally employed to optimize the defined fitness functions in order to identify the crystal orientation angles of turbine blades. Several corresponding examples demonstrated the accuracy, efficiency and general applicability of the proposed method.展开更多
Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically...Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically studied.Herein,it is experimentally and theoretically demonstrated that the water contact angle(105.9°)of the(111)surface is higher than that(91.7°)of the(220)surface,associated with the lower surface free energy(28.44 mN/m)of(111)surface than that(38.48 mN/m)of(220)surface.Furthermore,cerium oxide films with(111)-terminated surface are annealed at 300℃ and 600℃ for1 h,respectively.The lattice constant increases(5.4594Å<5.4613Å<5.4670Å)with decreasing the annealing temperature(600℃>300℃>the as-deposited),leading to the increased water contact angle(96.7°<96.8°<99.0°).The First-principles calculation provides microscopic insights into the wetting mechanism,originating from the weakened adsorption capacity of the(111)surface for water molecules with the increasing lattice constant.展开更多
This study was conducted to investigate the influence of pulse parameters on the surface morphology and crystal orientation of the tungsten coatings electrodeposited on pure copper substrates. The deposited coatings w...This study was conducted to investigate the influence of pulse parameters on the surface morphology and crystal orientation of the tungsten coatings electrodeposited on pure copper substrates. The deposited coatings were analyzed by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive spectrometer （EDS）. SEM analysis indicates that pulse parameters have significant influences on the surface morphology of the deposited coatings. Meanwhile, the change in grain size of the tungsten coatings demonstrates that the change in frequency and duty cycle could cause the variation of nucleation rate and grain growth of deposits. Moreover, no obvious diffusion layer at the coating/substrate interface is found by line analysis of EDS. XRD results reveal that tungsten coatings are of bcc structure and the preferred orientation of the deposits varies with duty cycle and period.展开更多
Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation en...Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.展开更多
We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perf...We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.展开更多
CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope ...CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope (SEM); the corrosion resistance was done by three electrodes system, and the natural sea water was used as corrosion medium. The results demonstrate that the strongest crystal orientation is transformed from crystal plane (200) to (111); moreover, the crystal plane (111) whose intensity is the strongest on the cross section and vertical section with REF causes the tubes be rolled easily, and the corrosion resistance of the billet is increasing with REF. As a result, properties of CuNi10Fe1Mn alloy tubes can be improved by REF.展开更多
The relationship between the solid/liquid interface and the crystal orientation for pure magnesium,which grows in fashion of cellular crystal in unidirectional solidification,was investigated.The results show that the...The relationship between the solid/liquid interface and the crystal orientation for pure magnesium,which grows in fashion of cellular crystal in unidirectional solidification,was investigated.The results show that the energy of the solid/liquid interface is the lowest during cellular crystal growth of pure magnesium;and the solid/liquid interface is covered by the basal face{0001}and by the crystal face made up of three atoms located at the orientation{0001}0100and two atoms located at the inner of magnesium crystal cell.The strongest bond is formed in the direction of 61.9°viating from the growth direction,and the second strong bond is formed in the directions of 8.5°d 47.7°espectively,deviating from the growth direction.The angle between the basal face{0001} and the growth direction is 61.9°he theoretical analysis results are basically consistent with the experimental results from SUSUMU et al.展开更多
We investigated the effect of aligning crystal orientation in the microstructures containing sub micro-sized grains on the thermoelectric properties for polycrystalline Bi-Te materials.Bi-Te powder,prepared through th...We investigated the effect of aligning crystal orientation in the microstructures containing sub micro-sized grains on the thermoelectric properties for polycrystalline Bi-Te materials.Bi-Te powder,prepared through the conventional pulverization process,was sufficiently dispersed in an appropriate solvent,and then was formed into c-axis aligned green bodies under a designated high magnetic field.The green bodies were sintered with spark-plasma-sintering machine.The degree of crystal alignment of sintered bodies was examined with the electron-back-scatter-diffraction SEM and the X-ray diffraction patterns.It was observed that for both p and n type thermoelectric Bi-Te materials,aligning crystal orientation properly made electrical resistivity decreased with keeping Seebeck coefficient and thermal conductivity remained unchanged.As a typical result,the aligned Bi-Te material with the magnetic field of 10 tesla showed 30%enhancement of the thermoelectric performance.展开更多
The characteristics of nano scale n-type double gate MOSFETs with（100） and（110） surfaces are studied using 3 D full band ensemble Monte Carlo simulator. The anisotropic surface scattering mechanism is investigated...The characteristics of nano scale n-type double gate MOSFETs with（100） and（110） surfaces are studied using 3 D full band ensemble Monte Carlo simulator. The anisotropic surface scattering mechanism is investigated. The（100） case is sensitive to the gate voltage more than the（110） case. The impact of crystal orientation and surface scattering on transport features mainly reflects in the carrier velocity distribution. The electron transport features with（100） direction are greater than that with（110） direction, but are more likely to be affected by the surface scattering.展开更多
The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were mea...The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were measured and the stress-strain hysteresis loops for selected cy- cles were recorded.The energy losses.friction stresses,back stresses and shape展开更多
The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indi...The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indicate that the value of cyclic stress σ,internal friction Q^(-1)and ultrasonic attenuation △α depend obviously on the slip orientation.There are large differences in above three parameters for different slip orientation Al crystals.In early stage of fatigue life,σ and △α increase and Q^(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q^(-1)and σ get the valley and the peak,respectively,at same cycles.展开更多
The explicit representations for tensorial Fourier expansion of 3_D crystal orientation distribution functions (CODFs) are established. In comparison with that the coefficients in the mth term of the Fourier expansion...The explicit representations for tensorial Fourier expansion of 3_D crystal orientation distribution functions (CODFs) are established. In comparison with that the coefficients in the mth term of the Fourier expansion of a 3_D ODF make up just a single irreducible mth_order tensor, the coefficients in the mth term of the Fourier expansion of a 3_D CODF constitute generally so many as 2m+1 irreducible mth_order tensors. Therefore, the restricted forms of tensorial Fourier expansions of 3_D CODFs imposed by various micro_ and macro_scopic symmetries are further established, and it is shown that in most cases of symmetry the restricted forms of tensorial Fourier expansions of 3_D CODFs contain remarkably reduced numbers of mth_order irreducible tensors than the number 2m+1 . These results are based on the restricted forms of irreducible tensors imposed by various point_group symmetries, which are also thoroughly investigated in the present part in both 2_ and 3_D spaces.展开更多
The pearl or nacreous layer of mollusk shell is composed of CaCO 3 aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials. we analyzed ...The pearl or nacreous layer of mollusk shell is composed of CaCO 3 aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials. we analyzed the crystal orientation of nacreous layers with different color prepared from fresh water clams Hyriopsis cumingii Lea by X ray diffraction . The results show that the crystal CaCO 3 orientation on specific plane is responsible for the color of pearl and nacreous pearl color.展开更多
Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current stud...Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current studies have come across many challenges,e.g.serious capacity degradation and inferior rate capability caused by severe structural collapse and sluggish reaction kinetics,highlighting the need for further improvement in efficient utilization of the layered space.Herein,this study employs a novel crystal orientation regulation to enhance the performance of BiOBr electrode by a facile solvothermal method to efficiently utilize the interlayered structu re.The delicate design of BiOBr(BOB)succeeds in maximizing the exposed(110)crystalline plane,providing efficient pathways for ion diffusion and streamlining the mass migration process.Moreover,the optimized band structure and the formation of oxygen vacancies in this designed material have been found,enabling high electrical conductivity,accelerating the charge transfer process and facilitating rapid reaction rate.Owing to the simultaneously enhanced mass transfer at the interlayers and the charge transfer during the phase conversion process,the BOB-110 electrode exhibits exceptional electrochemical performances,boasting impressive charge storage and rate capability(159 mAh g^(-1)at 4 A g^(-1)),and outstanding cycling stability of capacity retention around 75%(119 mAh g^(-1))even after 1000 cycles at a high current density of 4 A g^(-1).These findings underscore the substantial potential of BiOBr electrodes for future energy storage devices such as wearable electronics and power grids where the power output,lifespan,and affordability are simultaneously required.展开更多
基金supported by the National Natural Science Foundation of China(22478211,22179067)the Major Fundamental Research Program of Natural Science Foundation of Shandong Province(ZR2022ZD10).
文摘Photoelectrochemical water oxidation reaction (PEC-WOR) as a sustainable route to produce H_(2)O_(2) is attractive but limited by low activity and poor product selectivity of photoanodes due to limited photogenerated charge efficiency and unfavorable thermodynamics. Herein, by crystal orientation engineering, the WO_(3) photoanode exposing (200) facets achieves both superior WOR activity (15.4 mA cm^(−2) at 1.76 VRHE) and high selectivity to H_(2)O_(2) (∼70%). Comprehensive experimental and theoretical investigations discover that the high PEC-WOR activity of WO_(3)-(200) is attributed to the rapid photogenerated charge separation/transfer both in bulk and at interfaces of WO_(3)-(200) facet, which reduces the charge transfer resistance. This, coupling with the unique defective hydrogen bonding network at the WO_(3)-(200)/electrolyte interface evidenced by operando PEC Fourier transform infrared spectroscopy, facilitating the outward-transfer of the WOR-produced H^(+), lowers the overall reaction barrier for the PEC-WOR. The superior selectivity of PEC-WOR to H_(2)O_(2) is ascribed to the unique defective hydrogen bonding network alleviated adsorption of ∗OH over the WO_(3)-(200) facet, which specially lowers the energy barrier of the 2-electron pathway, as compared to the 4-electron pathway. This work addresses the significant role of crystal orientation engineering on photoelectrocatalytic activity and selectivity, and sheds lights on the underlying PEC mechanism by understanding the water adsorption behaviors under illumination. The knowledge gained is expected to be extended to other photoeletrochemical reactions.
基金Project (51074105) supported by the National Natural Science Foundation of ChinaProjects (08DZ1130100, 10520706400) supported by the Science and Technology Commission of Shanghai Municipality, ChinaProject (2007CB613606) supported by the National Basic Research Program of China
文摘To increase efficiency and improve performance, reducing cost and emissions, advanced single crystal Ni-based superalloys are required in aerospace propulsion and power generating gas turbines. With the development of alloy, significant improvements in casting techniques have been achieved by introducing the directionally solidified （DS） casting process followed by single crystal （SX） technique. The deviation of preferred orientation of single crystal superalloys is one of the most important defects in casting. In directional solidification equipment with high temperature gradient, single crystal specimens of DZ417G alloy were prepared successfully by the modified Bridgeman method with spiral grain selector. The orientation was investigated by means of X-ray diffraction （XRD） and electron backscattered diffraction （EBSD）.The results show that the crystal selector with a smaller angle can effectively reduce the deviation of preferred orientation.
基金Projects(50374082,5071112018)supported by the National Natural Science Foundation of China
文摘Based on the high-purity single-crystal tungsten nanowire firstly prepared by the metal-catalyzed vapor-phase reaction method, molecular dynamics method was used to calculate tensile stress-strain curves and simulate microscopic deformation structures of the single-crystal tungsten nanowires with different crystal orientations of 〈100〉, 〈110〉and 〈111〉, in order to reveal the effect of crystal orientation on their tensile mechanical properties and failure mechanisms. Research results show that all of the stress-strain curves are classified into four stages： elastic stage, damage stage, yielding stage and failure stage, where 〈100〉orientation has a special hardening stage after yielding and two descending stages. The crystal orientation has little effect on elastic modulus but great effect on tensile strength, yielding strength and ductility, depending on different atomic surface energies and principal sliding planes. The calculated values of elastic modulus are in good agreement with the tested values of elastic modulus.
基金the financial support from the National Natural Science Foundation of China (No. 51961013)the Natural Science Foundation of Jiangxi Province, China (No. 20202ACBL214002)+2 种基金the China Postdoctoral Science Foundation (Nos. 2019M660159 and 2020T130093)the Postdoctoral Science Foundation of Jiangxi Province, China (No. 2019KY25)the Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology, China (No. JXUSTQJYX2020022)。
文摘The effect of the crystal orientations and precipitates on the corrosion behavior of Al-Cu-Li single crystals was studied by scanning electron microscopy, transmission electron microscopy, optical microscopy, immersion testing in exfoliation corrosion solution, and electrochemical testing. The results show that the corrosion rates of different orientations of the aged Al-Cu-Li alloy increase in the order of (001) 1 phase deteriorated the corrosion resistance of the Al-Cu-Li alloy, and the degree of deterioration differed in different crystal plane orientations. The severe localized corrosion of the aged alloy propagates along the crystallography and extends along the {111}Alplane in the form of corrosion bands.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51401210 and 51271186),the National High Technology Research and Development Program of China(“863 Program”,Grant No.2014AA041701)
文摘A nickel-based superalloy was deposited onto a single crystal substrate based on epitaxial laser metal forming （E-LMF）. The microstructure development in two depositions has been researched. For the first time, the crystal orientation of dendrites varying beyond 20° was found when the dendrites deflected in deposition. In addition, a new grain boundary was found between different orientation dendrites in a grain, and the detected grain boundary angle was 23°. The result shows that flowing field in laser pool is responsible for this phenomenon.
文摘Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Results reveal that Mg-4 wt% Zn alloy with dendritic microstructure exhibits typical { 0002} basal texture along growth direction. Based on this, the effect of grain orientation on corrosion behavior of directionally solidified Mg-4 wt% Zn alloy in 0.9 wt% NaCl solution was investigated. Result shows that {0002} oriented planes have better corrosion resistance than {1120} and {1010 } ones, which is attributed to a synergistic effect of surface energy, atomic packing density and the stability of oxidation film,2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology,
基金co-supported by the National Natural Science Foundation of China (Nos. 51405460, 11372128 and 51175244)National Safety Academic Foundation of China (No. U1730129)the Collaborative Innovation Center of Advanced Aero-Engine, Jiangsu Province Key Laboratory of Aerospace Power System,the Key Laboratory of Aero-Engine Thermal Environment and Structure, Ministry of Industry and Information Technology
文摘A novel approach to identify the crystal orientation of turbine blades with anisotropy materials is proposed. Based on enhanced mode basis, with the main advantages of its efficiency,accuracy and general applicability, the blade vibration mode of each order is linearly constructed by several specified mode shapes, which are obtained from the considered turbine blade with specified crystal orientations correspondingly. Then, a surrogate model based on Kriging method is introduced for constructing the condensed perturbed matrix of stiffness in order to improve the efficiency even further. The constructed surrogate model allows to perform the modal analysis of turbine blades with arbitrary crystal orientations in higher efficiency, due to the fact that the elements of condensed perturbed matrix of stiffness are considered in construction of the surrogate model rather than concerning the perturbation of all the elements of the initial stiffness matrix for the blade. Genetic algorithm is finally employed to optimize the defined fitness functions in order to identify the crystal orientation angles of turbine blades. Several corresponding examples demonstrated the accuracy, efficiency and general applicability of the proposed method.
基金financially supported by the National Natural Science Foundation of China(Nos.51901062 and U1908220)the Natural Science Foundation of Zhejiang Province(No.LR18E010001)+1 种基金the Key R&D Project of Zhejiang Province(Nos.2019C01121 and 2021C01023)the LiaoNing Revitalization Talents Program(No.XLYC1807177)。
文摘Cerium oxide possesses intrinsic hydrophobic properties ascribed to the unique electronic structure.However,the relationship between the crystal structure and hydrophobicity of cerium oxide has not been systematically studied.Herein,it is experimentally and theoretically demonstrated that the water contact angle(105.9°)of the(111)surface is higher than that(91.7°)of the(220)surface,associated with the lower surface free energy(28.44 mN/m)of(111)surface than that(38.48 mN/m)of(220)surface.Furthermore,cerium oxide films with(111)-terminated surface are annealed at 300℃ and 600℃ for1 h,respectively.The lattice constant increases(5.4594Å<5.4613Å<5.4670Å)with decreasing the annealing temperature(600℃>300℃>the as-deposited),leading to the increased water contact angle(96.7°<96.8°<99.0°).The First-principles calculation provides microscopic insights into the wetting mechanism,originating from the weakened adsorption capacity of the(111)surface for water molecules with the increasing lattice constant.
基金financially supported by the National Magnetic Confinement Fusion Program of China (No. 2015GB109003)National Natural Science Foundation of China (Nos. 51171006 and 51471015)
文摘This study was conducted to investigate the influence of pulse parameters on the surface morphology and crystal orientation of the tungsten coatings electrodeposited on pure copper substrates. The deposited coatings were analyzed by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive spectrometer （EDS）. SEM analysis indicates that pulse parameters have significant influences on the surface morphology of the deposited coatings. Meanwhile, the change in grain size of the tungsten coatings demonstrates that the change in frequency and duty cycle could cause the variation of nucleation rate and grain growth of deposits. Moreover, no obvious diffusion layer at the coating/substrate interface is found by line analysis of EDS. XRD results reveal that tungsten coatings are of bcc structure and the preferred orientation of the deposits varies with duty cycle and period.
基金the financial support from the National Key R&D program of China(2021YFF0500501 and 2021YFF0500504)the Fundamental Research Funds for the Central Universities(YJS2213 and JB211408)+1 种基金the National Natural Science Foundation of China(61874083)the Joint Research Funds of Department of Science&Technology of Shaanxi Province and Northwestern Polytechnical University(No.2020GXLH-Z-014)
文摘Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.
文摘We use laser-scanning nonlinear imaging microscopy in atomically thin transition metal dichalcogenides(TMDs)to reveal information on the crystalline orientation distribution,within the 2D lattice.In particular,we perform polarization-resolved second-harmonic generation(PSHG)imaging in a stationary,raster-scanned chemical vapor deposition(CVD)-grown WS2 flake,in order to obtain with high precision a spatially resolved map of the orientation of its main crystallographic axis(armchair orientation).By fitting the experimental PSHG images of sub-micron resolution into a generalized nonlinear model,we are able to determine the armchair orientation for every pixel of the image of the 2D material,with further improved resolution.This pixel-wise mapping of the armchair orientation of 2D WS2 allows us to distinguish between different domains,reveal fine structure,and estimate the crystal orientation variability,which can be used as a unique crystal quality marker over large areas.The necessity and superiority of a polarization-resolved analysis over intensity-only measurements is experimentally demonstrated,while the advantages of PSHG over other techniques are analysed and discussed.
基金financially supported by the Fundamental Research Fund for the Zhejiang Provincial Laboratory of Testing and Deep Processing for Measuring and Cutting Tools(No.ZD201202)
文摘CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope (SEM); the corrosion resistance was done by three electrodes system, and the natural sea water was used as corrosion medium. The results demonstrate that the strongest crystal orientation is transformed from crystal plane (200) to (111); moreover, the crystal plane (111) whose intensity is the strongest on the cross section and vertical section with REF causes the tubes be rolled easily, and the corrosion resistance of the billet is increasing with REF. As a result, properties of CuNi10Fe1Mn alloy tubes can be improved by REF.
基金Project(2007T078)supported by the Outstanding Innovation Team in Colleges and Universities of Education Department of Liaoning Province,China
文摘The relationship between the solid/liquid interface and the crystal orientation for pure magnesium,which grows in fashion of cellular crystal in unidirectional solidification,was investigated.The results show that the energy of the solid/liquid interface is the lowest during cellular crystal growth of pure magnesium;and the solid/liquid interface is covered by the basal face{0001}and by the crystal face made up of three atoms located at the orientation{0001}0100and two atoms located at the inner of magnesium crystal cell.The strongest bond is formed in the direction of 61.9°viating from the growth direction,and the second strong bond is formed in the directions of 8.5°d 47.7°espectively,deviating from the growth direction.The angle between the basal face{0001} and the growth direction is 61.9°he theoretical analysis results are basically consistent with the experimental results from SUSUMU et al.
基金Item Sponsored by Energy Efficiency&Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Ministry of Knowledge Economy,Republic of Korea(2007EID11P050000)the DGIST Basic Research Program of the Ministry of Education,Science and Technology(MoEST),Republic of Korea(12-EN-01)
文摘We investigated the effect of aligning crystal orientation in the microstructures containing sub micro-sized grains on the thermoelectric properties for polycrystalline Bi-Te materials.Bi-Te powder,prepared through the conventional pulverization process,was sufficiently dispersed in an appropriate solvent,and then was formed into c-axis aligned green bodies under a designated high magnetic field.The green bodies were sintered with spark-plasma-sintering machine.The degree of crystal alignment of sintered bodies was examined with the electron-back-scatter-diffraction SEM and the X-ray diffraction patterns.It was observed that for both p and n type thermoelectric Bi-Te materials,aligning crystal orientation properly made electrical resistivity decreased with keeping Seebeck coefficient and thermal conductivity remained unchanged.As a typical result,the aligned Bi-Te material with the magnetic field of 10 tesla showed 30%enhancement of the thermoelectric performance.
基金Project supported by the National High-Tech R&D Program(No.2015AA016501)
文摘The characteristics of nano scale n-type double gate MOSFETs with（100） and（110） surfaces are studied using 3 D full band ensemble Monte Carlo simulator. The anisotropic surface scattering mechanism is investigated. The（100） case is sensitive to the gate voltage more than the（110） case. The impact of crystal orientation and surface scattering on transport features mainly reflects in the carrier velocity distribution. The electron transport features with（100） direction are greater than that with（110） direction, but are more likely to be affected by the surface scattering.
文摘The symmetrical push-pull fatigue tests at strain amplitude of 2×10~3 with different slip orientation of Al single crystals,were carried out at room temperature in air.The peak stresses of various cycles were measured and the stress-strain hysteresis loops for selected cy- cles were recorded.The energy losses.friction stresses,back stresses and shape
文摘The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indicate that the value of cyclic stress σ,internal friction Q^(-1)and ultrasonic attenuation △α depend obviously on the slip orientation.There are large differences in above three parameters for different slip orientation Al crystals.In early stage of fatigue life,σ and △α increase and Q^(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q^(-1)and σ get the valley and the peak,respectively,at same cycles.
文摘The explicit representations for tensorial Fourier expansion of 3_D crystal orientation distribution functions (CODFs) are established. In comparison with that the coefficients in the mth term of the Fourier expansion of a 3_D ODF make up just a single irreducible mth_order tensor, the coefficients in the mth term of the Fourier expansion of a 3_D CODF constitute generally so many as 2m+1 irreducible mth_order tensors. Therefore, the restricted forms of tensorial Fourier expansions of 3_D CODFs imposed by various micro_ and macro_scopic symmetries are further established, and it is shown that in most cases of symmetry the restricted forms of tensorial Fourier expansions of 3_D CODFs contain remarkably reduced numbers of mth_order irreducible tensors than the number 2m+1 . These results are based on the restricted forms of irreducible tensors imposed by various point_group symmetries, which are also thoroughly investigated in the present part in both 2_ and 3_D spaces.
文摘The pearl or nacreous layer of mollusk shell is composed of CaCO 3 aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials. we analyzed the crystal orientation of nacreous layers with different color prepared from fresh water clams Hyriopsis cumingii Lea by X ray diffraction . The results show that the crystal CaCO 3 orientation on specific plane is responsible for the color of pearl and nacreous pearl color.
基金supported by the CRF grant of the Hong Kong Research Grant Council(C5031-20G)the Guang Dong Basic and Applied Basic Research Foundation(2024A1515013283)the Seed Fund of University Research Committee(2201100760)。
文摘Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current studies have come across many challenges,e.g.serious capacity degradation and inferior rate capability caused by severe structural collapse and sluggish reaction kinetics,highlighting the need for further improvement in efficient utilization of the layered space.Herein,this study employs a novel crystal orientation regulation to enhance the performance of BiOBr electrode by a facile solvothermal method to efficiently utilize the interlayered structu re.The delicate design of BiOBr(BOB)succeeds in maximizing the exposed(110)crystalline plane,providing efficient pathways for ion diffusion and streamlining the mass migration process.Moreover,the optimized band structure and the formation of oxygen vacancies in this designed material have been found,enabling high electrical conductivity,accelerating the charge transfer process and facilitating rapid reaction rate.Owing to the simultaneously enhanced mass transfer at the interlayers and the charge transfer during the phase conversion process,the BOB-110 electrode exhibits exceptional electrochemical performances,boasting impressive charge storage and rate capability(159 mAh g^(-1)at 4 A g^(-1)),and outstanding cycling stability of capacity retention around 75%(119 mAh g^(-1))even after 1000 cycles at a high current density of 4 A g^(-1).These findings underscore the substantial potential of BiOBr electrodes for future energy storage devices such as wearable electronics and power grids where the power output,lifespan,and affordability are simultaneously required.
