A series of selective dissolution experunents were conducted on the hydrogeinc ferromanganese crusts collected near Line Island to study the geochemistry of Mn, Fe, Cu, Co, Ni and Ti. Despite of the fact that the very...A series of selective dissolution experunents were conducted on the hydrogeinc ferromanganese crusts collected near Line Island to study the geochemistry of Mn, Fe, Cu, Co, Ni and Ti. Despite of the fact that the very close intergrowth between amorphous ferric oxyhydroxides and 6-MnO2 exists in the hydrogenic ferromanganese crusts, there is no isomorphous substitution between iron and manganese. This is because the two elements in oxides have different crystal chemistry and geochemistry, such assertion bemg in agreement with the results of selective dissolution experiments. Transitional metal elements such as Cu, Co, Ni and Ti are enriched in different phases, i.e. Ni and Co are incorporated into 6-MnO2 while Cu and Ti are incorporated into ferric oxyhy- droxides. The distributions of the elements in amorphous ferric oxyhydroxides and δ-MnO2 are controlled by the existing states of the elements in the seawater and the crystal chemistry and geochemistry of these elements/inns in oxides.展开更多
Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unu...Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unusual phenomena in terms of alloying effects.In the present work,we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms.In terms of rapid solidified structure,the additions of early transition elements always inhibit the for-mation of pre-existingα-Fe crystals even eliminate them,and the additions that could produce larger atomic mismatch parameter(δ)and negative mixing enthalpy(△H_(mix))show stronger effects.In terms of nanocrystallization behaviors,the increases inδand negative△H_(mix) weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the an-nealed alloys and deteriorate their magnetic softness,while the excessive increases inδand negativeHmix could significantly suppress the growth ofα-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness.展开更多
The pressure-actuated metal seal with soft metal coating has been widely used in complex working conditions such as high temperature,low temperature and high pressure.The investigation of the characteristics and bindi...The pressure-actuated metal seal with soft metal coating has been widely used in complex working conditions such as high temperature,low temperature and high pressure.The investigation of the characteristics and binding strength of the transition layer between the soft metal coating and the superalloy substrate is important to improve the sealing performance and to model and simplify the working through-process of metal sealing.The distribution characteristics of elements at soft metal-substrate interface and the binding strength between coating and substrate under different thicknesses and material combinations of coating layer were studied by experimental methods.The results indicate that the thickness of soft metal coating has little influence on the interface morphology of GH4169-Cu,GH4169-Ag and Cu-Ag,but has an influence on the thickness of transition layer between different metals,while this influence is weakened with increasing the coating thickness,and the thickness of transition layer is about 2μm when the coating thickness is more than 30μm.The cross-cut test shows that the Cu,Ag and Cu-Ag coatings are all well combined with nickel-based superalloy GH4169 substrate.The materials of soft metal,i.e.the coating materials,have significant influence on the characteristic of transition layer and the surface characteristics of coating after cross-cut test.展开更多
In this work, the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements. The shape functions of the transition plate elements are derived based...In this work, the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements. The shape functions of the transition plate elements are derived based on a practical rule. The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements. The mesh convergence rates of the models including the transition elements are compared with the regular element models. To verify the developed elements, simple tests are demonstrated and various elasto-plastic problems are solved. Their results are compared with ANSYS results.展开更多
Infrared emissivity was studied in Zno.99Mo.olO （M is Mn, Fe or Ni） and Znl_xCoxO （x=0.01, 0.02, 0.03 and 0.04） powders synthesized by solid-state reaction at various temperatures. XRD patterns confirm the wurtzit...Infrared emissivity was studied in Zno.99Mo.olO （M is Mn, Fe or Ni） and Znl_xCoxO （x=0.01, 0.02, 0.03 and 0.04） powders synthesized by solid-state reaction at various temperatures. XRD patterns confirm the wurtzite structure of the prepared samples. No peaks of other phases arising from impurities are detected in Mn- and Co-doped ZnO, hut the peaks of ZnFe204 and NiO are observed in Zno.99Feo.010 and Zno.99Nio.o10. The SEM observations indicate that with larger grain sizes than those of Zn0.99Feo.010 and Zno.99Ni0.010, Co-doped ZnO exhibits smooth grain surfaces. The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.010 are much stronger than those in Co-doped ZnO. Co ions are dissolved into the ZnO lattice with Co2＋ state from XPS spectra analysis. The infrared emissivity results imply that the emissivity of Zno.99Ni0.010 is the highest （0.829） and that of Zno.99C00.010 is the lowest （0.784） at 1 200 ℃. The emissivity of Zno.99Co0.010 decreases to the minimum （0.752） at 1 150 ℃ and then increases with growing calcination temperature. As the Co doping content grows, the emissivity of Co-doped ZnO calcined at 1 200 ℃ falls to 0.758 in the molar fraction of 3% and then ascends.展开更多
1.IntroductionThe influence of substitution of variouselements for Fe on the magnetic propertiesof the NdFeBalloy has been investi-gated by several authors,among which theAl substitution can increase the coercivity[1]...1.IntroductionThe influence of substitution of variouselements for Fe on the magnetic propertiesof the NdFeBalloy has been investi-gated by several authors,among which theAl substitution can increase the coercivity[1]and the addition of both Co and Al has beenproved to have a positive effect on im-proving both the coercivity and other per-展开更多
In this paper, we shall give a group of new isoparametric elements suitable .for St.Wnant's torsion of a bar with vertical cracks. These elements are eight-pointisoparametric element, quarter eight-Point isoparame...In this paper, we shall give a group of new isoparametric elements suitable .for St.Wnant's torsion of a bar with vertical cracks. These elements are eight-pointisoparametric element, quarter eight-Point isoparametric element and eight-pointisoparametric transition element. Among these elements, the second and the thirdelements possess the singularity of order r-1/2 at crack tip. Using these elements, wehave completed the calculations of St. Venant's torsion for a cylinder with a radialvertical crack. The calculated results show that the isoparametric elements given bythis paper have ideal accuracy. good convergence. high speed of convergence, lowfreedom and little computational time, and so they can be widely applied to practice.展开更多
Bond connectivity topological index S i based on chemical bonds was defined by using a matrix method.And S i is formed by atomic parameters such as the number of valence electrons,the number of the highest main quan...Bond connectivity topological index S i based on chemical bonds was defined by using a matrix method.And S i is formed by atomic parameters such as the number of valence electrons,the number of the highest main quantum of atoms and the bonding electrons and bond parameters such as the length of bonds,the electronegativity difference of bonding atoms.The molecular bond connectivity topological index S is composed of S i.The thermodynamic properties of saturated hydrocarbons,unsaturated hydrocarbons,oxygen organic,methane halide and transitional element compounds and the molecular bond connectivity topological index S have an optimal correlative relationship.展开更多
A novel optoelectronic functional circuit with heterojunction phototransistors (HPTs) and resonant tunneling diodes (RTDs) is described,which presents the function of both photocurrent switching and photo-current latc...A novel optoelectronic functional circuit with heterojunction phototransistors (HPTs) and resonant tunneling diodes (RTDs) is described,which presents the function of both photocurrent switching and photo-current latching.These behaviors have been demonstrated by simulating experiments and circuit simulation.Furthermore,basing on photo-current latching behavior,various photo-controlled basis logic elements such as delayed flip-flop (DFF) can be designed and fabricated.展开更多
Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made ...Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.展开更多
The concentration of 39 trace elements in coal from the late Permian taken from the eastern Yunnan-western Guizhou region was determined using inductively coupled plasma mass spectrometry. It was found that the mean c...The concentration of 39 trace elements in coal from the late Permian taken from the eastern Yunnan-western Guizhou region was determined using inductively coupled plasma mass spectrometry. It was found that the mean content of Ti, V, Cr, Mo, Co, Ni, Y, and Zr is higher than the national average. The occurrence of Mn, Ni, and Co in the different coalfields is distinctly different. Most of the enriched transition metal elements exist mainly as inorganic minerals. In the Zhina coalfield, Co, Ni, and Nb are primarily associated with sulfur. Mn, Cs, and Mo are mostly sulfides. Almost all Co was organic and a significant part of the Ni is also organic in the Liupanshui coalfield. Cs, Co, and Ni are related to sulfur in the coal taken from eastern Yunnan. Carbonate is the main form of Mn in the coal from eastern Yunnan and the Liupanshui coalfield. Ti is the oxide in the coal samples where Ti is enriched. Zr is in the form of zircon in the samples where Zr is enriched. The situation for most of the transition metal elements is consistent with terrestrial genesis. Coal seams are universally influenced by the sea. The strongly seawater effected peat bog with a reductive and alkaline environment favors the relative enrichment of Mn. A reducing environment is conducive to transition metal element enrichment.展开更多
MgH2is considered as a promising hydrogen storage material for its high hydrogen storage capacity,low cost and abundant resource advantages.However,the low kinetics and high enthalpy formation of MgH_(2)limit its wide...MgH2is considered as a promising hydrogen storage material for its high hydrogen storage capacity,low cost and abundant resource advantages.However,the low kinetics and high enthalpy formation of MgH_(2)limit its wide application.From the perspective of adding catalysts to enhance the hydrogen storage properties of Mg-MgH_(2),this article elaborated the main catalysts based on Ti and Nb transition elements,including single oxide catalysts,binary oxides catalysts(combined with Ni,Na,Sr,V,etc.),multiple catalysts bound to carbon,and composite catalysts with Ti and Nb elements combined with MXene phase.Moreover,the main pathways of various catalysts to reduce the reaction activity and broaden the hydrogen desorption channel were also analyzed.The Ti-based catalysts can enhance the reactive sites of the matrix by forming multivalent states,while Nb-based catalysts broaden the hydrogen reaction channels by forming tiny Nb.By improving the size structure and enhancing the grain size stability,combined with carbon materials should be the future considerations.展开更多
The all-inorganic lead-free vacancy-ordered perovskite offers a promising avenue toward nontoxic and stable optoelectronic materials.Herein,we present a first-principles study of the structural stability,optical absor...The all-inorganic lead-free vacancy-ordered perovskite offers a promising avenue toward nontoxic and stable optoelectronic materials.Herein,we present a first-principles study of the structural stability,optical absorption,electronic structure,and mechanical behavior of Cs_(2)BCl_(6) compounds with B-site substitutions(B]Ge,Sn,Pb,Cr,Mo,W,Ti,Zr,and Hf).The structural analysis shows that the Cs_(2)BCl_(6) perovskite with face-centered cubes has a stable chemical environment,especially Cs_(2)HfCl_(6),Cs_(2)WCl_(6),and Cs_(2)PbCl_(6).Hf4^(+) and W4^(+) with high-energy d-state external electron configurations can further lower the valence band maximum position of the Cs_(2)BCl_(6) structures and thus increase the band gap,assisting in tuning the optical absorption and emission properties of these structures in the optoelectronic application.For the light absorption properties of Cs_(2)BCl_(6) materials,the best light absorption properties have been concluded for Ti4^(+),Cr4^(+),and Pb4^(+)-based perovskite in the visible range due to a suitable band gap.Therefore,the excellent optical absorption and electronic properties make these vacancy-ordered perovskites promising candidates for optoelectronic applications.展开更多
The partitioning behavior of trace elements is of key importance for understanding the geochemical process and material cycle mechanism in subduction zones.This paper focuses on the advances and prospects on the studi...The partitioning behavior of trace elements is of key importance for understanding the geochemical process and material cycle mechanism in subduction zones.This paper focuses on the advances and prospects on the studies of trace element partitioning in subduction zones from the following four aspects.(1)The properties of fluids derived from subducting slabs and their ability in element transport.How slab-derived solute-rich fluids and supercritical fluids are formed and what the roles and key control factors of these fluids are in transferring of elements(especially the high field strength elements)from slab to wedge are discussed.We point out that the detailed investigations of supercritical fluids may provide a new perspective for the element migration mechanism,material cycle process,arc magma genesis and so on.(2)The behavior of transition elements during mantle wedge melting.The behavior of the first row transition elements(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)in the mantle partial melting process is compatible or incompatible,depending on residual mineral assemblage and physicochemical conditions.The partitioning behavior of the elements such as Sc,Ti,Co,Ni and Zn whose valence states do not change in the melting process mainly depends on the residual mineral assemblage and temperature,whereas the partitioning behavior of the multivalent elements such as V and Fe is also the function of oxygen fugacity(fO_(2))in addition to mineral assemblage and temperature.Therefore,the partitioning behavior of transition elements has important applications in tracing lithologic inhomogeneity and fO_(2)of the mantle wedges.(3)The specificity of element partitioning behavior during arc magma evolution.Garnet has Dy/Yb partitioning behavior different from amphibole,and rutile has Nb/Ta partitioning behavior different from amphibole.Dy/Yb and Nb/Ta partitioning differences for these minerals enable to distinguish the specific evolution process of arc magmas.The Dy/Yb and Nb/Ta generally decrease with the increase of SiO_(2)in arc magmas,indicating that amphibole fractionation should be the most important during arc magma differentiation.(4)The behavior of sulfur and chalcophile elements and porphyry metallogeny.In subduction zones,the behavior of chalcophile elements such as Cu and Au is controlled by sulfide and fluid.Therefore,the stability of sulfide,the time at which the fluid exsolves from the melt relative to sulfide saturation,the fluid/sulfide mass ratio and fluid/melt Cu and Au partition coefficients in intermediate-felsic magma-H_(2)O systems are especially important in understanding Cu and Au enrichment in magma-hydrothermal processes.Intermediate-felsic magmas mainly originate from the differentiation of arc magmas at lower crustal reservoirs,and thus the fluid exsolution from the lower crustal reservoirs and the fluid/melt and fluid/sulfide partition coefficients of Cu and Au should be the keys to understanding quantitatively how Cu and Au are migrated from the deep crust to the shallow site of mineralization.展开更多
CONSPECTUS:The success of lithium-ion batteries(LIBs)has driven the vigorous development of mobile electronic devices and electric vehicles.As a key component of LIBs,the energy density of traditional cathode material...CONSPECTUS:The success of lithium-ion batteries(LIBs)has driven the vigorous development of mobile electronic devices and electric vehicles.As a key component of LIBs,the energy density of traditional cathode materials has approached the theoretical limit,and the scarce transition metal elements have significantly increased the cost of batteries.In pursuit of cheap,abundant,and high-capacity materials,more attention is being focused on conversion-type cathodes.Sulfur(S),as a competitive nonmetallic element with extremely high theoretical capacity,has been widely studied in recent years.展开更多
In this paper, we discuss an adaptive hybrid stress finite element method on quadri- lateral meshes for linear elasticity problems. To deal with hanging nodes arising in the adaptive mesh refinement, we propose new tr...In this paper, we discuss an adaptive hybrid stress finite element method on quadri- lateral meshes for linear elasticity problems. To deal with hanging nodes arising in the adaptive mesh refinement, we propose new transition types of hybrid stress quadrilateral elements with 5 to 7 nodes. In particular, we derive a priori error estimation for the 5- node transition hybrid stress element to show that it is free from Poisson-locking, in the sense that the error bound in the a priori estimate is independent of the Lam~ constant A. We introduce~ for quadrilateral meshes, refinement/coarsening algorithms, which do not require storing the refinement tree explicitly, and give an adaptive algorithm. Finally, we provide some numerical results.展开更多
A MOS-NDR（negative differential resistance） transistor which is composed of four n-channel metaloxide -semiconductor field effect transistors（nMOSFETs） is fabricated in standard 0.35μm CMOS technology.This device...A MOS-NDR（negative differential resistance） transistor which is composed of four n-channel metaloxide -semiconductor field effect transistors（nMOSFETs） is fabricated in standard 0.35μm CMOS technology.This device exhibits NDR similar to conventional NDR devices such as the compound material based RTD（resonant tunneling diode） in current-voltage characteristics.At the same time it can realize a modulation effect by the third terminal. Based on the MOS-NDR transistor,a flexible logic circuit is realized in this work,which can transfer from the NAND gate to the NOR gate by suitably changing the threshold voltage of the MOS-NDR transistor.It turns out that MOS-NDR based circuits have the advantages of improved circuit compaction and reduced process complexity due to using the standard IC design and fabrication procedure.展开更多
This paper analyzes a nonconforming 5-node quadrilateral transition finite element for Poisson equation.This element was originally proposed by Choi and Park[Computers and Structures,32(1989),pp.295–304 and Thin-Wall...This paper analyzes a nonconforming 5-node quadrilateral transition finite element for Poisson equation.This element was originally proposed by Choi and Park[Computers and Structures,32(1989),pp.295–304 and Thin-Walled Structures,28(1997),pp.1–20]for the analysis of Mindlin plates.We show the consistency error of this element is only O(h^(1/2))over the transition edges of the quadrilateral subdivision.By modifying the shape functions with respect to mid-nodes,we get an improved version of the element for which the consistency error is O(h).Numerical examples are provided to verify the theoretical results.展开更多
The symmetry of rotation vibration spectra of molecule SiO_2 is described by means of group U(5). Grouptheory approach is adopted to give the matrix elements of stimulated Raman scattering in fiber. The cross sections...The symmetry of rotation vibration spectra of molecule SiO_2 is described by means of group U(5). Grouptheory approach is adopted to give the matrix elements of stimulated Raman scattering in fiber. The cross sectionsand gain coefficients of stimulated Raman scattering are given. The results are in good agreement with the experi-mental values.展开更多
基金supported by China Ocean Mineral Resources Research and Development Association (COMRA) (DY105-05-01-05)China Ministry of Education (205089)China National Natural Science Foundation (40076015).
文摘A series of selective dissolution experunents were conducted on the hydrogeinc ferromanganese crusts collected near Line Island to study the geochemistry of Mn, Fe, Cu, Co, Ni and Ti. Despite of the fact that the very close intergrowth between amorphous ferric oxyhydroxides and 6-MnO2 exists in the hydrogenic ferromanganese crusts, there is no isomorphous substitution between iron and manganese. This is because the two elements in oxides have different crystal chemistry and geochemistry, such assertion bemg in agreement with the results of selective dissolution experiments. Transitional metal elements such as Cu, Co, Ni and Ti are enriched in different phases, i.e. Ni and Co are incorporated into 6-MnO2 while Cu and Ti are incorporated into ferric oxyhy- droxides. The distributions of the elements in amorphous ferric oxyhydroxides and δ-MnO2 are controlled by the existing states of the elements in the seawater and the crystal chemistry and geochemistry of these elements/inns in oxides.
基金supported by the National Key R&D Program of China(No.2021YFB3803004)the National Natural Science Foundation of China(Nos.52101239 and 52171153)+4 种基金Ningbo Natural Science Foundation(No.2021J222)the“Pioneer”R&D Program of Zhejiang Province(No.2023C01075)Youth Innovation Promotion Association CAS(No.2021294)Zhejiang Provincial Key Research and Development Projects(No.2021C01033)CITIC Group Major Science and Technology Innovation Project(HT-FZB-2022190).
文摘Unique rapid solidified structure and nanocrystallization mechanism enable the Fe-based nanocrystalline alloys with high Cu content excellent soft magnetic properties and good manufacturability,and also results in unusual phenomena in terms of alloying effects.In the present work,we systematically studied the influence rules of early transition elements on the rapid solidified structure and nanocrystallization behaviors of Fe-Si-B-Cu soft magnetic alloys with high Cu content and explored the related mechanisms.In terms of rapid solidified structure,the additions of early transition elements always inhibit the for-mation of pre-existingα-Fe crystals even eliminate them,and the additions that could produce larger atomic mismatch parameter(δ)and negative mixing enthalpy(△H_(mix))show stronger effects.In terms of nanocrystallization behaviors,the increases inδand negative△H_(mix) weaken the competitive growth between the pre-existing nanocrystals during annealing and then coarsen the nanostructure of the an-nealed alloys and deteriorate their magnetic softness,while the excessive increases inδand negativeHmix could significantly suppress the growth ofα-Fe crystals by diffusion inhibition during annealing and thus remarkable refine the nanostructure of the annealed alloys and improve their magnetic softness.
基金National Natural Science Foundation of China(52375378)National Key Laboratory of Metal Forming Technology and Heavy Equipment(S2308100.W12)Huxiang High-Level Talent Gathering Project of Hunan Province(2021RC5001)。
文摘The pressure-actuated metal seal with soft metal coating has been widely used in complex working conditions such as high temperature,low temperature and high pressure.The investigation of the characteristics and binding strength of the transition layer between the soft metal coating and the superalloy substrate is important to improve the sealing performance and to model and simplify the working through-process of metal sealing.The distribution characteristics of elements at soft metal-substrate interface and the binding strength between coating and substrate under different thicknesses and material combinations of coating layer were studied by experimental methods.The results indicate that the thickness of soft metal coating has little influence on the interface morphology of GH4169-Cu,GH4169-Ag and Cu-Ag,but has an influence on the thickness of transition layer between different metals,while this influence is weakened with increasing the coating thickness,and the thickness of transition layer is about 2μm when the coating thickness is more than 30μm.The cross-cut test shows that the Cu,Ag and Cu-Ag coatings are all well combined with nickel-based superalloy GH4169 substrate.The materials of soft metal,i.e.the coating materials,have significant influence on the characteristic of transition layer and the surface characteristics of coating after cross-cut test.
文摘In this work, the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements. The shape functions of the transition plate elements are derived based on a practical rule. The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements. The mesh convergence rates of the models including the transition elements are compared with the regular element models. To verify the developed elements, simple tests are demonstrated and various elasto-plastic problems are solved. Their results are compared with ANSYS results.
基金Project(2009K06_03) supported by the Scientific and Technological Program of Shaanxi Province,China
文摘Infrared emissivity was studied in Zno.99Mo.olO （M is Mn, Fe or Ni） and Znl_xCoxO （x=0.01, 0.02, 0.03 and 0.04） powders synthesized by solid-state reaction at various temperatures. XRD patterns confirm the wurtzite structure of the prepared samples. No peaks of other phases arising from impurities are detected in Mn- and Co-doped ZnO, hut the peaks of ZnFe204 and NiO are observed in Zno.99Feo.010 and Zno.99Nio.o10. The SEM observations indicate that with larger grain sizes than those of Zn0.99Feo.010 and Zno.99Ni0.010, Co-doped ZnO exhibits smooth grain surfaces. The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.010 are much stronger than those in Co-doped ZnO. Co ions are dissolved into the ZnO lattice with Co2＋ state from XPS spectra analysis. The infrared emissivity results imply that the emissivity of Zno.99Ni0.010 is the highest （0.829） and that of Zno.99C00.010 is the lowest （0.784） at 1 200 ℃. The emissivity of Zno.99Co0.010 decreases to the minimum （0.752） at 1 150 ℃ and then increases with growing calcination temperature. As the Co doping content grows, the emissivity of Co-doped ZnO calcined at 1 200 ℃ falls to 0.758 in the molar fraction of 3% and then ascends.
文摘1.IntroductionThe influence of substitution of variouselements for Fe on the magnetic propertiesof the NdFeBalloy has been investi-gated by several authors,among which theAl substitution can increase the coercivity[1]and the addition of both Co and Al has beenproved to have a positive effect on im-proving both the coercivity and other per-
文摘In this paper, we shall give a group of new isoparametric elements suitable .for St.Wnant's torsion of a bar with vertical cracks. These elements are eight-pointisoparametric element, quarter eight-Point isoparametric element and eight-pointisoparametric transition element. Among these elements, the second and the thirdelements possess the singularity of order r-1/2 at crack tip. Using these elements, wehave completed the calculations of St. Venant's torsion for a cylinder with a radialvertical crack. The calculated results show that the isoparametric elements given bythis paper have ideal accuracy. good convergence. high speed of convergence, lowfreedom and little computational time, and so they can be widely applied to practice.
文摘Bond connectivity topological index S i based on chemical bonds was defined by using a matrix method.And S i is formed by atomic parameters such as the number of valence electrons,the number of the highest main quantum of atoms and the bonding electrons and bond parameters such as the length of bonds,the electronegativity difference of bonding atoms.The molecular bond connectivity topological index S is composed of S i.The thermodynamic properties of saturated hydrocarbons,unsaturated hydrocarbons,oxygen organic,methane halide and transitional element compounds and the molecular bond connectivity topological index S have an optimal correlative relationship.
文摘A novel optoelectronic functional circuit with heterojunction phototransistors (HPTs) and resonant tunneling diodes (RTDs) is described,which presents the function of both photocurrent switching and photo-current latching.These behaviors have been demonstrated by simulating experiments and circuit simulation.Furthermore,basing on photo-current latching behavior,various photo-controlled basis logic elements such as delayed flip-flop (DFF) can be designed and fabricated.
基金Funded by the National Natural Science Foundation of China(Nos.51604205 and 51774223)the Natural Science Foundation of Hubei Province(No.2016CFB268)+1 种基金the Fundamental Research Funds for the Central Universities(WUT:2016IVA046 and 2017IVB018)the Open Fund from Hubei Key Laboratory of Indust rial Fume and Dust Pollution Control(HBIK2015-02)
文摘Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.
基金financially supported by the National Natural Science Foundation of China (No. 40730422)
文摘The concentration of 39 trace elements in coal from the late Permian taken from the eastern Yunnan-western Guizhou region was determined using inductively coupled plasma mass spectrometry. It was found that the mean content of Ti, V, Cr, Mo, Co, Ni, Y, and Zr is higher than the national average. The occurrence of Mn, Ni, and Co in the different coalfields is distinctly different. Most of the enriched transition metal elements exist mainly as inorganic minerals. In the Zhina coalfield, Co, Ni, and Nb are primarily associated with sulfur. Mn, Cs, and Mo are mostly sulfides. Almost all Co was organic and a significant part of the Ni is also organic in the Liupanshui coalfield. Cs, Co, and Ni are related to sulfur in the coal taken from eastern Yunnan. Carbonate is the main form of Mn in the coal from eastern Yunnan and the Liupanshui coalfield. Ti is the oxide in the coal samples where Ti is enriched. Zr is in the form of zircon in the samples where Zr is enriched. The situation for most of the transition metal elements is consistent with terrestrial genesis. Coal seams are universally influenced by the sea. The strongly seawater effected peat bog with a reductive and alkaline environment favors the relative enrichment of Mn. A reducing environment is conducive to transition metal element enrichment.
基金supported by research programs of the National Natural Science Foundation of China(52101274)the Natural Science Foundation of Shandong Province(Nos.ZR2020QE011,ZR2022ME089)+2 种基金the Youth Top Talent Foundation of Yantai University(2219008)the Graduate Innovation Foundation of Yantai University(GGIFYTU2325)the College Student Innovation and Entrepreneurship Training Program Project(202311066088,202311066087)。
文摘MgH2is considered as a promising hydrogen storage material for its high hydrogen storage capacity,low cost and abundant resource advantages.However,the low kinetics and high enthalpy formation of MgH_(2)limit its wide application.From the perspective of adding catalysts to enhance the hydrogen storage properties of Mg-MgH_(2),this article elaborated the main catalysts based on Ti and Nb transition elements,including single oxide catalysts,binary oxides catalysts(combined with Ni,Na,Sr,V,etc.),multiple catalysts bound to carbon,and composite catalysts with Ti and Nb elements combined with MXene phase.Moreover,the main pathways of various catalysts to reduce the reaction activity and broaden the hydrogen desorption channel were also analyzed.The Ti-based catalysts can enhance the reactive sites of the matrix by forming multivalent states,while Nb-based catalysts broaden the hydrogen reaction channels by forming tiny Nb.By improving the size structure and enhancing the grain size stability,combined with carbon materials should be the future considerations.
基金supported by the National Key Research and Development Program of China(Grant 2021YFA0715600,2018YFB2202900)the National Natural Science Foundation of China(62304171,52192610,62274127,62274125,62374128)+2 种基金the China Postdoctoral Science Foundation(2022M722500,2023TQ0255)Key Research and Development Program of Shaanxi Province(Grant 2024GX-YBXM-512)the High-Performance Computing Platform of Xidian University,Guangdong Basic and Applied Basic Research Foundation(2023A1515030084).
文摘The all-inorganic lead-free vacancy-ordered perovskite offers a promising avenue toward nontoxic and stable optoelectronic materials.Herein,we present a first-principles study of the structural stability,optical absorption,electronic structure,and mechanical behavior of Cs_(2)BCl_(6) compounds with B-site substitutions(B]Ge,Sn,Pb,Cr,Mo,W,Ti,Zr,and Hf).The structural analysis shows that the Cs_(2)BCl_(6) perovskite with face-centered cubes has a stable chemical environment,especially Cs_(2)HfCl_(6),Cs_(2)WCl_(6),and Cs_(2)PbCl_(6).Hf4^(+) and W4^(+) with high-energy d-state external electron configurations can further lower the valence band maximum position of the Cs_(2)BCl_(6) structures and thus increase the band gap,assisting in tuning the optical absorption and emission properties of these structures in the optoelectronic application.For the light absorption properties of Cs_(2)BCl_(6) materials,the best light absorption properties have been concluded for Ti4^(+),Cr4^(+),and Pb4^(+)-based perovskite in the visible range due to a suitable band gap.Therefore,the excellent optical absorption and electronic properties make these vacancy-ordered perovskites promising candidates for optoelectronic applications.
基金the National Key Research and Development Program of China(Grant No.2018YFA0702704)the National Natural Science Foundation of China(Grant Nos.41573053&41921003)the Key Research Project of Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDJ-SSW-DQC012).
文摘The partitioning behavior of trace elements is of key importance for understanding the geochemical process and material cycle mechanism in subduction zones.This paper focuses on the advances and prospects on the studies of trace element partitioning in subduction zones from the following four aspects.(1)The properties of fluids derived from subducting slabs and their ability in element transport.How slab-derived solute-rich fluids and supercritical fluids are formed and what the roles and key control factors of these fluids are in transferring of elements(especially the high field strength elements)from slab to wedge are discussed.We point out that the detailed investigations of supercritical fluids may provide a new perspective for the element migration mechanism,material cycle process,arc magma genesis and so on.(2)The behavior of transition elements during mantle wedge melting.The behavior of the first row transition elements(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn)in the mantle partial melting process is compatible or incompatible,depending on residual mineral assemblage and physicochemical conditions.The partitioning behavior of the elements such as Sc,Ti,Co,Ni and Zn whose valence states do not change in the melting process mainly depends on the residual mineral assemblage and temperature,whereas the partitioning behavior of the multivalent elements such as V and Fe is also the function of oxygen fugacity(fO_(2))in addition to mineral assemblage and temperature.Therefore,the partitioning behavior of transition elements has important applications in tracing lithologic inhomogeneity and fO_(2)of the mantle wedges.(3)The specificity of element partitioning behavior during arc magma evolution.Garnet has Dy/Yb partitioning behavior different from amphibole,and rutile has Nb/Ta partitioning behavior different from amphibole.Dy/Yb and Nb/Ta partitioning differences for these minerals enable to distinguish the specific evolution process of arc magmas.The Dy/Yb and Nb/Ta generally decrease with the increase of SiO_(2)in arc magmas,indicating that amphibole fractionation should be the most important during arc magma differentiation.(4)The behavior of sulfur and chalcophile elements and porphyry metallogeny.In subduction zones,the behavior of chalcophile elements such as Cu and Au is controlled by sulfide and fluid.Therefore,the stability of sulfide,the time at which the fluid exsolves from the melt relative to sulfide saturation,the fluid/sulfide mass ratio and fluid/melt Cu and Au partition coefficients in intermediate-felsic magma-H_(2)O systems are especially important in understanding Cu and Au enrichment in magma-hydrothermal processes.Intermediate-felsic magmas mainly originate from the differentiation of arc magmas at lower crustal reservoirs,and thus the fluid exsolution from the lower crustal reservoirs and the fluid/melt and fluid/sulfide partition coefficients of Cu and Au should be the keys to understanding quantitatively how Cu and Au are migrated from the deep crust to the shallow site of mineralization.
基金supported by and the National Natural Science Foundation of China(grant nos.22350710185,22179120,and 21975225)the National Key Research and Development Program of China(2022YFB2402200).
文摘CONSPECTUS:The success of lithium-ion batteries(LIBs)has driven the vigorous development of mobile electronic devices and electric vehicles.As a key component of LIBs,the energy density of traditional cathode materials has approached the theoretical limit,and the scarce transition metal elements have significantly increased the cost of batteries.In pursuit of cheap,abundant,and high-capacity materials,more attention is being focused on conversion-type cathodes.Sulfur(S),as a competitive nonmetallic element with extremely high theoretical capacity,has been widely studied in recent years.
文摘In this paper, we discuss an adaptive hybrid stress finite element method on quadri- lateral meshes for linear elasticity problems. To deal with hanging nodes arising in the adaptive mesh refinement, we propose new transition types of hybrid stress quadrilateral elements with 5 to 7 nodes. In particular, we derive a priori error estimation for the 5- node transition hybrid stress element to show that it is free from Poisson-locking, in the sense that the error bound in the a priori estimate is independent of the Lam~ constant A. We introduce~ for quadrilateral meshes, refinement/coarsening algorithms, which do not require storing the refinement tree explicitly, and give an adaptive algorithm. Finally, we provide some numerical results.
基金supported by the National Natural Science Foundation of China(Nos.60536030,60502005)the National High Technology Research and Development Program of China(Nos.2007AA01Z2A5,2006AA01Z239,2007AA03Z454).
文摘A MOS-NDR（negative differential resistance） transistor which is composed of four n-channel metaloxide -semiconductor field effect transistors（nMOSFETs） is fabricated in standard 0.35μm CMOS technology.This device exhibits NDR similar to conventional NDR devices such as the compound material based RTD（resonant tunneling diode） in current-voltage characteristics.At the same time it can realize a modulation effect by the third terminal. Based on the MOS-NDR transistor,a flexible logic circuit is realized in this work,which can transfer from the NAND gate to the NOR gate by suitably changing the threshold voltage of the MOS-NDR transistor.It turns out that MOS-NDR based circuits have the advantages of improved circuit compaction and reduced process complexity due to using the standard IC design and fabrication procedure.
基金supported by Natural Science Foundation of China(10771150)the National Basic Research Program of China(2005CB321701)the Program for New Century Excellent Talents in University(NCET-07-0584).
文摘This paper analyzes a nonconforming 5-node quadrilateral transition finite element for Poisson equation.This element was originally proposed by Choi and Park[Computers and Structures,32(1989),pp.295–304 and Thin-Walled Structures,28(1997),pp.1–20]for the analysis of Mindlin plates.We show the consistency error of this element is only O(h^(1/2))over the transition edges of the quadrilateral subdivision.By modifying the shape functions with respect to mid-nodes,we get an improved version of the element for which the consistency error is O(h).Numerical examples are provided to verify the theoretical results.
文摘The symmetry of rotation vibration spectra of molecule SiO_2 is described by means of group U(5). Grouptheory approach is adopted to give the matrix elements of stimulated Raman scattering in fiber. The cross sectionsand gain coefficients of stimulated Raman scattering are given. The results are in good agreement with the experi-mental values.
