Specific grades of high-entropy alloys(HEAs)can provide opportunities for optimizing properties toward high-temperature applications.In this work,the Co-based HEA with a chemical composition of Co_(47.5)Cr_(30)Fe_(7.5...Specific grades of high-entropy alloys(HEAs)can provide opportunities for optimizing properties toward high-temperature applications.In this work,the Co-based HEA with a chemical composition of Co_(47.5)Cr_(30)Fe_(7.5)Mn_(7.5)Ni_(7.5)(at%)was chosen.The refractory metallic elements hafnium(Hf)and molybdenum(Mo)were added in small amounts(1.5at%)because of their well-known positive effects on high-temperature properties.Inclusion characteristics were comprehensively explored by using a two-dimensional cross-sectional method and extracted by using a three-dimensional electrolytic extraction method.The results revealed that the addition of Hf can reduce Al_(2)O_(3)inclusions and lead to the formation of more stable Hf-rich inclusions as the main phase.Mo addition cannot influence the inclusion type but could influence the inclusion characteristics by affecting the physical parameters of the HEA melt.The calculated coagulation coefficient and collision rate of Al_(2)O_(3)inclusions were higher than those of HfO_(2)inclusions,but the inclusion amount played a larger role in the agglomeration behavior of HfO_(2)and Al_(2)O_(3)inclusions.The impurity level and active elements in HEAs were the crucial factors affecting inclusion formation.展开更多
Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been wid...Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been widely investigated for the synthesis of particles, and arrays of oriented nanorods and nanotubes. In this paper, based on the ideal crystal shapes predicted by the chemical bonding theory, we have developed some potential chemical strategies to tune the microstructure of functional materials, ZnS and Nb205 nanotube arrays, MgO wiskers and nestlike spheres, and cubic phase Cu2O microcrystals were synthesized here to elucidate these strategies. We describe their controlled crystallization processes and illustrate the detailed key factors controlling their growth by examining various reaction parameters. Current results demonstrate that our designed chemical strategies for tuning microstructure of functional materials are applicable to several technologically important materials, and therefore may be used as a versatile and effective route to the controllable synthesis of other inorganic functional materials.展开更多
A novel method was proposed to calculate the crystal morphology (or growth habit) on the basis of chemical bond analysis. All constituent chemical bonds were distinguished as relevant and independent bonds according t...A novel method was proposed to calculate the crystal morphology (or growth habit) on the basis of chemical bond analysis. All constituent chemical bonds were distinguished as relevant and independent bonds according to their variations during the crystallization process. By employing the current method, the influence of specific growth conditions on the crystal morphology can be considered in the structure analysis process. The ideal morphologies of both KDP (KH2PO4) and ADP (NH4H2PO4) crystals were calculated and compared with our obtained crystallites at room temperature, which validates the present calculation method very well.展开更多
In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrM...In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR furnace.The main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS core.The Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification processes.Therefore,inclusions can act as nucleation sites for carbide layer precipitation.The ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted ingot.The M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy results.The substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)carbide.Therefore,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)carbide.The Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid inclusion.The increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag.展开更多
Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate (Florisil) of three particle size ranges (mean diameters of 112, 200 and 425 ...Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate (Florisil) of three particle size ranges (mean diameters of 112, 200 and 425 μm) was compared to the corresponding adsorption onto activated carbon and Amberlite XAD-2. The best fit of the kinetic results was achieved by a pseudo second-order equation. The equilibrium data were found to be well represented by the Langmuir isotherm equation. Amberlite XAD-2, an unspecific adsorbent capable of adsorbing exclusively through a surface effect, exhibited a poor dye uptake, confirming that the adsorption mechanism on Florisil was due to electrostatic attraction and ion exchange. Moreover, the comparison between Florisil and the other adsorbents was performed on the basis of the evaluation of the surface area and pore volume occupied by the adsorbed dye.展开更多
A novel water cluster [Mn(phen)2·H2O·Cl]·p-FBA·3H2O (p-FBA = p-fluorobenzoic acid and phen = 1,10-phenanthroline) was synthesized by the hydrothermal reaction of MnCl2 with p-FBA and phen at 1...A novel water cluster [Mn(phen)2·H2O·Cl]·p-FBA·3H2O (p-FBA = p-fluorobenzoic acid and phen = 1,10-phenanthroline) was synthesized by the hydrothermal reaction of MnCl2 with p-FBA and phen at 150 ℃ and characterized by elemental analysis,IR spectra and TG. Its crystal structure was determined by X-ray single-crystal diffraction study. The crystal belongs to the triclinic system,space group P1,with a = 10.5768(1),b = 11.5960(1),c = 12.9916(2) ,α = 101.816(2),β = 95.397(2),γ = 103.052(2)o,V = 1502.8(3) 3,Z = 2,Dc = 1.463 g/cm3,R = 0.0399 and wR = 0.0997. The crystal structure shows that the manganese(Ⅱ ) ion is six-coordinated by four nitrogen atoms,one chloride ion and one oxygen atom forming a distorted octahedral coordination geometry. The structure includes three acyclically connected water molecules and one coordinated water molecule thus forming a (H2O)4 water cluster. This water pattern forms a cross-linked discrete ring. The steady (H2O)4 is further extended into a cage-like structure by the hydrogen-bonding interaction formed by dissociative aqua molecule and Cl-ligand. The dimer structure is further extended into a one-dimensional (1D) structure through C-H···O interaction. π···π Stacking interaction among adjacent phen aromatic rings further stabilizes the crystal structure.展开更多
On the basis of crystallographic structure of lithium niobate (LN), the bonding energy was quantitatively calculated by the bond valence sum model, which was employed to investigate the crystal growth. A possible rela...On the basis of crystallographic structure of lithium niobate (LN), the bonding energy was quantitatively calculated by the bond valence sum model, which was employed to investigate the crystal growth. A possible relationship between the crystal growth habit and chemical bonding energy of LN crystals are found. It is found that the higher the bond energy, the slower the growth rate, and the more important the plane. The analytical results indicate that (012) plane is the most influential face for the LN crystal growth, which consists well with the standard card (JCPDS Card: 20-0631) and our previous experimental observation. The current work shows that the chemical bond analysis of LN crystals allows us to predict its growth habit and thus to obtain the expected morphology during the spontaneous growth.展开更多
Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical...Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the <100> direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.展开更多
A novel metal-organic complex Cu(p-FBA)2(phen)(H2O) (p-FBA = p-fluorobenzoic acid,phen = 1,10-phenanthroline) has been synthesized and structurally characterized by X-ray single-crystal diffraction,elemental a...A novel metal-organic complex Cu(p-FBA)2(phen)(H2O) (p-FBA = p-fluorobenzoic acid,phen = 1,10-phenanthroline) has been synthesized and structurally characterized by X-ray single-crystal diffraction,elemental analysis and IR spectra. The crystal belongs to triclinic,space group P1 with a = 7.8043(7),b = 10.4069(9),c = 14.3658(13) ,α = 105.3170(10),β = 96.877(2),γ = 96.7580(10)o,V = 1103.56(17) 3,Mr = 539.96,Z = 2,Dc = 1.625 g/cm3,μ = 1.050 mm-1,F(000) = 550,the final R = 0.0324 and wR = 0.0952. In the crystal,the structure consists of discrete molecules containing a five-coordinate copper(Ⅱ ) in a distorted square pyramidal configuration. Intramolecular O-H···O hydrogen bonds,weak intermolecular C-H···O hydrogen bonds and π-π stacking link the molecules into a one-dimensional chain structure. The study on the title complex has been performed with quantum chemistry calculation by means of G03W package on the Lanl2dz basis set. The stabilities of the complex together with the orbital energies and composition characteristics of some frontier molecular orbitals have been investigated.展开更多
The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg)...The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg). In naphthenic oil which is a good solvent for the butadiene blocks, but a non-solvent for the styrene blocks and PPE, PPE was selectively included into styrene blocks in SBS, and induced the increase of the Tg of these blocks. The melting temperature determined by viscoelastic measurements and softening temperature of the gels were elevated by adding PPE, while no significant change was detected by adding polystyrene. The gel became opaque by adding PPE, and partially separated phases were observed by field emission scanning electron microscopy (FE-SEM). The dependence of the viscoelastic behavior on the PPE concentration can be explained by the structural change observed by FE-SEM.展开更多
Lithium–sulfur batteries are one of the attractive next-generation energy storage systems owing to theienvironmental friendliness,low cost,and high specific energy densities.However,the low electrical conductivity of...Lithium–sulfur batteries are one of the attractive next-generation energy storage systems owing to theienvironmental friendliness,low cost,and high specific energy densities.However,the low electrical conductivity of sulfur,shuttling of soluble intermediate polysulfides between electrodes,and low capacitretention have hampered their commercial use.To address these issues,we use a halloysitemodulated(H-M)separator in a lithium–sulfur battery to mitigate the shuttling problem.The H-M separator acts as a mutual Coulombic repulsion in lithium-sulfur batteries,thereby selectively permitting Lions and efficiently suppressing the transfer of undesired lithium polysulfides to the Li anode sideMoreover,the use of halloysite switches the surface of the separator from hydrophobic to hydrophilicconsequently improving the electrolyte wettability and adhesion between the separator and cathodeWhen sulfur-multi-walled carbon nanotube(S-MWCNT)composites are used as cathode active materialsa lithium–sulfur battery with an H-M separator exhibits first discharge and charge capacities of 1587 an1527 m Ah g-1,respectively.Moreover,there is a consistent capacity retention up to 100 cyclesAccordingly,our approach demonstrates an economical and easily accessible strategy for commercialization of lithium–sulfur batteries.展开更多
On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, t...On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.展开更多
Three alkaline earth silicate phosphors: Sr2MgSi2O7∶Eu, Dy, Gd, Sr3MgSi2O8∶Eu, Dy, Gd and Sr2MgSi2O7∶Eu, Dy were prepared and their luminescent properties were investigated. The Photoluminescence (PL) measurements ...Three alkaline earth silicate phosphors: Sr2MgSi2O7∶Eu, Dy, Gd, Sr3MgSi2O8∶Eu, Dy, Gd and Sr2MgSi2O7∶Eu, Dy were prepared and their luminescent properties were investigated. The Photoluminescence (PL) measurements indicated that the phosphors gave a longer emitting phosphorescence phenomenon by comparing with those without Gd2O3 activator, in which a better afterglow characteristic was observed by adding Gd2O3 to the phosphors. While little influence on the structure of luminescent materials was observed via XRD spectra, and obvious emission wavelength shift was exhibited due to the differences in the structure parameters of the two hosts. The results revealed that the improvement was due to nonequivalent substitution to produce more e-traps, and energy transfer from Gd3+ to Dy3+, to boost the performance of Sr2MgSi2O7∶Eu, Dy phosphor. Role of Gd3+ co-doped into Sr2MgSi2O7∶Eu, Dy matrix and the possible long-lasting phosphorescence progress were discussed.展开更多
On the basis of the Li-site vacancy model, the non-stoichiometric defects in LN crystals, i.e., anti-site defects NbLi and corresponding lithium vacancy defects VLi, were investigated by the bond valence model. Accord...On the basis of the Li-site vacancy model, the non-stoichiometric defects in LN crystals, i.e., anti-site defects NbLi and corresponding lithium vacancy defects VLi, were investigated by the bond valence model. According to the valence sum rule, 4 VLi sites must emerge in the nearest lattices of NbLi, and thus form a neutral cluster with the center, NbLi(VLi)4Nb5O15. The bond graph of the defect cluster was given, which reveals the ideal chemical bonding characteristics of defect clusters. Combining the possible configuration of defect clusters and the ideal bond lengths in the bond graph, the size of defect clusters in the LN crystallographic frame is estimated as 0.9~1.2 nm in diameter.展开更多
We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi...We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi-carrier transport instinct of the electronic transport. Current-controlled negative differential resistance(CC-NDR) observed in currentvoltage characteristics below ~ 7 K is closely associated with the intrinsic transition ~ 5 K of FeSb2, which is, however,mediated by extrinsic current-induced Joule heating effect. The antimony crystallized in a preferred orientation within the FeSb2 lattice in the high-temperature synthesis process leaves its fingerprint in the de Haas-Van Alphen(dHvA) oscillations, and results in the regular angular dependence of the oscillating frequencies. Nevertheless, possible existence of intrinsic non-trivial states cannot be completely ruled out. Our findings call for further theoretical and experimental studies to explore novel physics on flux-free grown FeSb_2 crystals.展开更多
A novel porous lanthanide-organic coordination polymer, [Nd(H2O)(HnicO)(TP)]·2H2O (1) (H2nicO=2-hydroxynicotinic acid, TP= terephthalate), was prepared under hydrothermal condition and characterized by ...A novel porous lanthanide-organic coordination polymer, [Nd(H2O)(HnicO)(TP)]·2H2O (1) (H2nicO=2-hydroxynicotinic acid, TP= terephthalate), was prepared under hydrothermal condition and characterized by single-crystal X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Compound 1 exhibited a flexible coordination geometry of lanthanide ions, which possessed a three-dimensional (3D) open framework with one-dimensional (1D) channels containing lattice water molecules. This framework structure exhibited a high stability up to 330℃ after removing free water molecules. A homometallic supramolecular framework (Zn(HnicO)2(H2O)2 (2)) was obtained due to the competitive reaction between organic ligands, Nd3+ and Zn2+ ions. The results showed that on the basis of the soft-hard/acid-base principle the coordination selection between metal ions and organic ligands played an essential role in the smart construction of lanthanide architectures.展开更多
Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for comm...Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.展开更多
This study investigated the effects of KCl treatment on microstructure and thermoelectric properties of n-type Bi_(2)Te_(2.7)Se_(0.3)(BTS)thermoelectric materials.The innovative KCl treatment was originally intended t...This study investigated the effects of KCl treatment on microstructure and thermoelectric properties of n-type Bi_(2)Te_(2.7)Se_(0.3)(BTS)thermoelectric materials.The innovative KCl treatment was originally intended to introduce nanopores through selective dissolution of KCl from a mixture of thermoelectric materials and KCl.However,it unexpectedly induced substantial variations in material composition and microstructure during the subsequent spark plasma sintering(SPS)process.Hydroxyl groups adsorbed on the powder surface during the dissolution resulted in the emergence of a Bi_(2)TeO_(5) secondary phase within the BTS matrix after the SPS process at 450℃.The concentration of Bi_(2)TeO_(5) increased with an increase in the KCl content.Furthermore,a remarkable grain growth occurred at low KCl concentrations,likely due to the liquid-phase formation in a Te-rich composition during SPS.However,excessive Bi_(2)TeO_(5) at higher KCl concentrations hindered grain growth.These variations in the microstructure had complex effects on electrical properties:The TeBi antisite defects increased the electron concentration,and Bi_(2)TeO_(5) reduced electron mobility.Additionally,the lattice thermal conductivity decreased due to the presence of Bi_(2)TeO_(5),from 0.8 W·m^(−1)·K^(−1) at 298 K for the pristine BTS to 0.6 W·m^(−1)·K^(−1) at 298 K for BTS treated with 1 wt%KCl.These insights allowed precise adjustments of the electrical and thermal conductivities,leading to an enhancement in the maximum value of figure-of-merit(ZT)from 0.76 to 0.96 through the selective dissolution of KCl approach.We believe that our observations potentially enable advances in thermoelectric materials by engineering microstructures.展开更多
Advanced hybrid nanomaterials(nanohybrids)with unique tailored morphologies and compositions have been used for the target-oriented catalysts due to the structural or supportive properties of each moiety and the syner...Advanced hybrid nanomaterials(nanohybrids)with unique tailored morphologies and compositions have been used for the target-oriented catalysts due to the structural or supportive properties of each moiety and the synergistic properties of the individual components.The rational design and development of nanohybrids by integrating highly porous silica into a nano metal-organic framework(NMOF)are expected to enable unique nanospace engineering in the resulting systems to optimize their utility in the target areas.Herein,we report the design and fabrication of advanced nanohybrids composed of dendritic fibrous nanosilica(DFNS)and DFNS/gold(DFNS/Au)hybrids as the core and zinc-based NMOF(Zn-NMOF)as the shell(DFNS@Zn-NMOF)through a solution-based approach.The combined fibrous morphology of DFNS and micropores of NMOF can be directly employed for nanospace engineering in the resulting multi-compositional and hierarchical systems in a controllable manner.The DFNS/Au dots@Zn-NMOF nanohybrid shows improved catalytic performance in the Knoevenagel condensation reaction,attributed mainly to the cooperative effect stemming from the suitably organized configurations of each component.展开更多
基金the Swedish Foundation for International Cooperation in Research and Higher Education(STINT,Nos.IB2020-8781 and IB20229228)for the collaboration between KTH<U(Sweden),HYU(Korea),and NEU(China)VINNOVA(No.2022-01216),the SSF Strategic Mobility Grant(No.SM22-0039),the?Forsk(No.23-540),and the Swedish Steel Producers’Association(Jernkontoret),in particular,Axel Ax:-son Johnsons forskningsfond,Prytziska fondennr 2,Gerhard von Hofstens Stiftelse f?r Metallurgisk forskning,and Stiftelsen?veringenj?ren Gustaf Janssons Jernkontorsfond for the financial support.Key Lab of EPM(NEU)is acknowledged for supporting the partial FactSage calculation+2 种基金the Key Laboratory for Ferrous Metallurgy and Resources Utilization of the Min-istry of Education and Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking(No.FMRUlab-22-1)for supporting this researchThe Natural Science Foundation of Liaoning Province,China(No.2023MSBA-135)the Fundamental Research Funds for the Central Universities(No.N2409006)are also acknowledged。
文摘Specific grades of high-entropy alloys(HEAs)can provide opportunities for optimizing properties toward high-temperature applications.In this work,the Co-based HEA with a chemical composition of Co_(47.5)Cr_(30)Fe_(7.5)Mn_(7.5)Ni_(7.5)(at%)was chosen.The refractory metallic elements hafnium(Hf)and molybdenum(Mo)were added in small amounts(1.5at%)because of their well-known positive effects on high-temperature properties.Inclusion characteristics were comprehensively explored by using a two-dimensional cross-sectional method and extracted by using a three-dimensional electrolytic extraction method.The results revealed that the addition of Hf can reduce Al_(2)O_(3)inclusions and lead to the formation of more stable Hf-rich inclusions as the main phase.Mo addition cannot influence the inclusion type but could influence the inclusion characteristics by affecting the physical parameters of the HEA melt.The calculated coagulation coefficient and collision rate of Al_(2)O_(3)inclusions were higher than those of HfO_(2)inclusions,but the inclusion amount played a larger role in the agglomeration behavior of HfO_(2)and Al_(2)O_(3)inclusions.The impurity level and active elements in HEAs were the crucial factors affecting inclusion formation.
基金the financial support of the program for the New Century Excellent Talents in University(Grant No.NCET-05-0278)the National Natural Science Foundation of China(Grant No.20471012)+1 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.200322)the Research Fund for the Doctoral Program of Higher Education(Grant No.20040141004).
文摘Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been widely investigated for the synthesis of particles, and arrays of oriented nanorods and nanotubes. In this paper, based on the ideal crystal shapes predicted by the chemical bonding theory, we have developed some potential chemical strategies to tune the microstructure of functional materials, ZnS and Nb205 nanotube arrays, MgO wiskers and nestlike spheres, and cubic phase Cu2O microcrystals were synthesized here to elucidate these strategies. We describe their controlled crystallization processes and illustrate the detailed key factors controlling their growth by examining various reaction parameters. Current results demonstrate that our designed chemical strategies for tuning microstructure of functional materials are applicable to several technologically important materials, and therefore may be used as a versatile and effective route to the controllable synthesis of other inorganic functional materials.
基金Project supported by the National Natural Science Foundation of China (20471012), Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), Research Fund for the Doctoral Program of Higher Education (20040141004) and Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘A novel method was proposed to calculate the crystal morphology (or growth habit) on the basis of chemical bond analysis. All constituent chemical bonds were distinguished as relevant and independent bonds according to their variations during the crystallization process. By employing the current method, the influence of specific growth conditions on the crystal morphology can be considered in the structure analysis process. The ideal morphologies of both KDP (KH2PO4) and ADP (NH4H2PO4) crystals were calculated and compared with our obtained crystallites at room temperature, which validates the present calculation method very well.
基金the Korea Evaluation Institute of Industrial Technology(KEIT,No.20009956)the Korea Institute for Advancement of Technology(KIAT,No.P0023676,HRD Program for Industrial Innovation)+1 种基金funded by the Ministry of Trade,Industry and Energy(MOTIE),Koreathe Swedish Foundation for International Cooperation in Research and Higher Education(STINT)for supporting the collaboration between KTH(Sweden)and Hanyang University(Korea)。
文摘In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR furnace.The main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS core.The Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification processes.Therefore,inclusions can act as nucleation sites for carbide layer precipitation.The ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted ingot.The M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy results.The substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)carbide.Therefore,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)carbide.The Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid inclusion.The increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag.
文摘Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate (Florisil) of three particle size ranges (mean diameters of 112, 200 and 425 μm) was compared to the corresponding adsorption onto activated carbon and Amberlite XAD-2. The best fit of the kinetic results was achieved by a pseudo second-order equation. The equilibrium data were found to be well represented by the Langmuir isotherm equation. Amberlite XAD-2, an unspecific adsorbent capable of adsorbing exclusively through a surface effect, exhibited a poor dye uptake, confirming that the adsorption mechanism on Florisil was due to electrostatic attraction and ion exchange. Moreover, the comparison between Florisil and the other adsorbents was performed on the basis of the evaluation of the surface area and pore volume occupied by the adsorbed dye.
基金supported by the Postgraduate Foundation of Taishan University (No. Y07-2-16)
文摘A novel water cluster [Mn(phen)2·H2O·Cl]·p-FBA·3H2O (p-FBA = p-fluorobenzoic acid and phen = 1,10-phenanthroline) was synthesized by the hydrothermal reaction of MnCl2 with p-FBA and phen at 150 ℃ and characterized by elemental analysis,IR spectra and TG. Its crystal structure was determined by X-ray single-crystal diffraction study. The crystal belongs to the triclinic system,space group P1,with a = 10.5768(1),b = 11.5960(1),c = 12.9916(2) ,α = 101.816(2),β = 95.397(2),γ = 103.052(2)o,V = 1502.8(3) 3,Z = 2,Dc = 1.463 g/cm3,R = 0.0399 and wR = 0.0997. The crystal structure shows that the manganese(Ⅱ ) ion is six-coordinated by four nitrogen atoms,one chloride ion and one oxygen atom forming a distorted octahedral coordination geometry. The structure includes three acyclically connected water molecules and one coordinated water molecule thus forming a (H2O)4 water cluster. This water pattern forms a cross-linked discrete ring. The steady (H2O)4 is further extended into a cage-like structure by the hydrogen-bonding interaction formed by dissociative aqua molecule and Cl-ligand. The dimer structure is further extended into a one-dimensional (1D) structure through C-H···O interaction. π···π Stacking interaction among adjacent phen aromatic rings further stabilizes the crystal structure.
基金Project supported by the National Natural Science Foundation of China (20471012), Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), the Research Fund for the Doctoral Program of Higher Education (20040141004) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘On the basis of crystallographic structure of lithium niobate (LN), the bonding energy was quantitatively calculated by the bond valence sum model, which was employed to investigate the crystal growth. A possible relationship between the crystal growth habit and chemical bonding energy of LN crystals are found. It is found that the higher the bond energy, the slower the growth rate, and the more important the plane. The analytical results indicate that (012) plane is the most influential face for the LN crystal growth, which consists well with the standard card (JCPDS Card: 20-0631) and our previous experimental observation. The current work shows that the chemical bond analysis of LN crystals allows us to predict its growth habit and thus to obtain the expected morphology during the spontaneous growth.
基金Project supported by the National Natural Science Foundation of China (20471012), Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), Research Fund for the Doctoral Program of Higher Education (20040141004) and Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the <100> direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.
基金supported by the Postgraduate Foundation of Taishan University (No. Y07--2-16)
文摘A novel metal-organic complex Cu(p-FBA)2(phen)(H2O) (p-FBA = p-fluorobenzoic acid,phen = 1,10-phenanthroline) has been synthesized and structurally characterized by X-ray single-crystal diffraction,elemental analysis and IR spectra. The crystal belongs to triclinic,space group P1 with a = 7.8043(7),b = 10.4069(9),c = 14.3658(13) ,α = 105.3170(10),β = 96.877(2),γ = 96.7580(10)o,V = 1103.56(17) 3,Mr = 539.96,Z = 2,Dc = 1.625 g/cm3,μ = 1.050 mm-1,F(000) = 550,the final R = 0.0324 and wR = 0.0952. In the crystal,the structure consists of discrete molecules containing a five-coordinate copper(Ⅱ ) in a distorted square pyramidal configuration. Intramolecular O-H···O hydrogen bonds,weak intermolecular C-H···O hydrogen bonds and π-π stacking link the molecules into a one-dimensional chain structure. The study on the title complex has been performed with quantum chemistry calculation by means of G03W package on the Lanl2dz basis set. The stabilities of the complex together with the orbital energies and composition characteristics of some frontier molecular orbitals have been investigated.
文摘The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg). In naphthenic oil which is a good solvent for the butadiene blocks, but a non-solvent for the styrene blocks and PPE, PPE was selectively included into styrene blocks in SBS, and induced the increase of the Tg of these blocks. The melting temperature determined by viscoelastic measurements and softening temperature of the gels were elevated by adding PPE, while no significant change was detected by adding polystyrene. The gel became opaque by adding PPE, and partially separated phases were observed by field emission scanning electron microscopy (FE-SEM). The dependence of the viscoelastic behavior on the PPE concentration can be explained by the structural change observed by FE-SEM.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2018R1C1B6004689)the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2020R1I1A306182111)the Electronics and Telecommunications Research Institute(ETRI)grant funded by the Korean government(21ZB1200,Development of ICT Materials,Components and Equipment Technologies)。
文摘Lithium–sulfur batteries are one of the attractive next-generation energy storage systems owing to theienvironmental friendliness,low cost,and high specific energy densities.However,the low electrical conductivity of sulfur,shuttling of soluble intermediate polysulfides between electrodes,and low capacitretention have hampered their commercial use.To address these issues,we use a halloysitemodulated(H-M)separator in a lithium–sulfur battery to mitigate the shuttling problem.The H-M separator acts as a mutual Coulombic repulsion in lithium-sulfur batteries,thereby selectively permitting Lions and efficiently suppressing the transfer of undesired lithium polysulfides to the Li anode sideMoreover,the use of halloysite switches the surface of the separator from hydrophobic to hydrophilicconsequently improving the electrolyte wettability and adhesion between the separator and cathodeWhen sulfur-multi-walled carbon nanotube(S-MWCNT)composites are used as cathode active materialsa lithium–sulfur battery with an H-M separator exhibits first discharge and charge capacities of 1587 an1527 m Ah g-1,respectively.Moreover,there is a consistent capacity retention up to 100 cyclesAccordingly,our approach demonstrates an economical and easily accessible strategy for commercialization of lithium–sulfur batteries.
基金Project supported by the National Natural Science Foundation of China (20471012), the Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), the Research Fund for the Doctoral Program of Higher Education (20040141004) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.
基金the National Natural Science Foundation (20376009)the Liaoning Natural Science Foundation(20032129) of China
文摘Three alkaline earth silicate phosphors: Sr2MgSi2O7∶Eu, Dy, Gd, Sr3MgSi2O8∶Eu, Dy, Gd and Sr2MgSi2O7∶Eu, Dy were prepared and their luminescent properties were investigated. The Photoluminescence (PL) measurements indicated that the phosphors gave a longer emitting phosphorescence phenomenon by comparing with those without Gd2O3 activator, in which a better afterglow characteristic was observed by adding Gd2O3 to the phosphors. While little influence on the structure of luminescent materials was observed via XRD spectra, and obvious emission wavelength shift was exhibited due to the differences in the structure parameters of the two hosts. The results revealed that the improvement was due to nonequivalent substitution to produce more e-traps, and energy transfer from Gd3+ to Dy3+, to boost the performance of Sr2MgSi2O7∶Eu, Dy phosphor. Role of Gd3+ co-doped into Sr2MgSi2O7∶Eu, Dy matrix and the possible long-lasting phosphorescence progress were discussed.
基金Project supported by the National Natural Science Foundation of China (20471012), Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), the Research Fund for the Doctoral Program of Higher Education (20040141004) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘On the basis of the Li-site vacancy model, the non-stoichiometric defects in LN crystals, i.e., anti-site defects NbLi and corresponding lithium vacancy defects VLi, were investigated by the bond valence model. According to the valence sum rule, 4 VLi sites must emerge in the nearest lattices of NbLi, and thus form a neutral cluster with the center, NbLi(VLi)4Nb5O15. The bond graph of the defect cluster was given, which reveals the ideal chemical bonding characteristics of defect clusters. Combining the possible configuration of defect clusters and the ideal bond lengths in the bond graph, the size of defect clusters in the LN crystallographic frame is estimated as 0.9~1.2 nm in diameter.
基金supported by Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2016ZT06D348)the National Natural Science Foundation of China(Grant No.11874193)+1 种基金the Shenzhen Fundamental Subject Research Program,China(Grant Nos.JCYJ20170817110751776 and JCYJ20170307105434022)The work at Brookhaven is supported by the US Department of Energy,Office of Basic Energy Sciences as part of the Computational Material Science Program(material synthesis)
文摘We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi-carrier transport instinct of the electronic transport. Current-controlled negative differential resistance(CC-NDR) observed in currentvoltage characteristics below ~ 7 K is closely associated with the intrinsic transition ~ 5 K of FeSb2, which is, however,mediated by extrinsic current-induced Joule heating effect. The antimony crystallized in a preferred orientation within the FeSb2 lattice in the high-temperature synthesis process leaves its fingerprint in the de Haas-Van Alphen(dHvA) oscillations, and results in the regular angular dependence of the oscillating frequencies. Nevertheless, possible existence of intrinsic non-trivial states cannot be completely ruled out. Our findings call for further theoretical and experimental studies to explore novel physics on flux-free grown FeSb_2 crystals.
基金Program for New Century Excellent Talents in University (NCET-05-0278)the National Natural Science Foundation of China (50872016)the Foundation for the Author of National Excellent Doctoral Dissertation of China (200322)
文摘A novel porous lanthanide-organic coordination polymer, [Nd(H2O)(HnicO)(TP)]·2H2O (1) (H2nicO=2-hydroxynicotinic acid, TP= terephthalate), was prepared under hydrothermal condition and characterized by single-crystal X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Compound 1 exhibited a flexible coordination geometry of lanthanide ions, which possessed a three-dimensional (3D) open framework with one-dimensional (1D) channels containing lattice water molecules. This framework structure exhibited a high stability up to 330℃ after removing free water molecules. A homometallic supramolecular framework (Zn(HnicO)2(H2O)2 (2)) was obtained due to the competitive reaction between organic ligands, Nd3+ and Zn2+ ions. The results showed that on the basis of the soft-hard/acid-base principle the coordination selection between metal ions and organic ligands played an essential role in the smart construction of lanthanide architectures.
基金supported by the Creative Materials Discovery Program (Grant No. 2018M3D1A1057844) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICTthe Basic Science Research Program through the NRF funded by the Ministry of Science, ICT and Future Planning (Grant No. 2021R1A2B5B01002879).
文摘Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.
基金This research was supported by the National Research Foundation(NRF)of Republic of Korea,funded by the Ministry of Science and ICT(Nos.NRF2020M3 D1A1110499 and NRF2022M3H4A1A04085311)the KU-KIST Research Program(No.2V09840-23-P025)his research was also supported by the Korea Institute of Science and Technology(No.2E32491).
文摘This study investigated the effects of KCl treatment on microstructure and thermoelectric properties of n-type Bi_(2)Te_(2.7)Se_(0.3)(BTS)thermoelectric materials.The innovative KCl treatment was originally intended to introduce nanopores through selective dissolution of KCl from a mixture of thermoelectric materials and KCl.However,it unexpectedly induced substantial variations in material composition and microstructure during the subsequent spark plasma sintering(SPS)process.Hydroxyl groups adsorbed on the powder surface during the dissolution resulted in the emergence of a Bi_(2)TeO_(5) secondary phase within the BTS matrix after the SPS process at 450℃.The concentration of Bi_(2)TeO_(5) increased with an increase in the KCl content.Furthermore,a remarkable grain growth occurred at low KCl concentrations,likely due to the liquid-phase formation in a Te-rich composition during SPS.However,excessive Bi_(2)TeO_(5) at higher KCl concentrations hindered grain growth.These variations in the microstructure had complex effects on electrical properties:The TeBi antisite defects increased the electron concentration,and Bi_(2)TeO_(5) reduced electron mobility.Additionally,the lattice thermal conductivity decreased due to the presence of Bi_(2)TeO_(5),from 0.8 W·m^(−1)·K^(−1) at 298 K for the pristine BTS to 0.6 W·m^(−1)·K^(−1) at 298 K for BTS treated with 1 wt%KCl.These insights allowed precise adjustments of the electrical and thermal conductivities,leading to an enhancement in the maximum value of figure-of-merit(ZT)from 0.76 to 0.96 through the selective dissolution of KCl approach.We believe that our observations potentially enable advances in thermoelectric materials by engineering microstructures.
基金This research was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT,MSICT)(NRF-2015R1A4A1041631 and NRF-2016R1A2B4009281)This research was also supported by the research fund of Hanyang University(201900000002834).
文摘Advanced hybrid nanomaterials(nanohybrids)with unique tailored morphologies and compositions have been used for the target-oriented catalysts due to the structural or supportive properties of each moiety and the synergistic properties of the individual components.The rational design and development of nanohybrids by integrating highly porous silica into a nano metal-organic framework(NMOF)are expected to enable unique nanospace engineering in the resulting systems to optimize their utility in the target areas.Herein,we report the design and fabrication of advanced nanohybrids composed of dendritic fibrous nanosilica(DFNS)and DFNS/gold(DFNS/Au)hybrids as the core and zinc-based NMOF(Zn-NMOF)as the shell(DFNS@Zn-NMOF)through a solution-based approach.The combined fibrous morphology of DFNS and micropores of NMOF can be directly employed for nanospace engineering in the resulting multi-compositional and hierarchical systems in a controllable manner.The DFNS/Au dots@Zn-NMOF nanohybrid shows improved catalytic performance in the Knoevenagel condensation reaction,attributed mainly to the cooperative effect stemming from the suitably organized configurations of each component.
基金Project(20080430895)supported by China Postdoctoral Science FoundationProject(2008RFQXG045)supported by Special Fund of Technological Innovation of Harbin,ChinaProject(HITQNJS.2009.021)supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology,China