In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structur...In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structure were prepared by an improved wet chemical method at different reaction temperature conditions.Consequently,fine platelike precursor(200-400 nm)and flower-like precursor(approximately 1.25μm)are obtained.After reduction and sintering,the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy.In the sample sintered from the platelike precursor,TiC particles with sizes in the range of40-300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors.However,in the sample sintered from the flower-like precursor,the TiC particles with sizes in the range of 50-700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix.As a result,the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor.The average bending strength of the sample sintered from the plate-like precursor is 655 MPa,which is higher than that of the sample sintered from the flower-like precursor(524 MPa).Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.展开更多
Two-dimensional(2 D)few-layerVSe_(2),V_(1-x)Fe_(x)Se_(2) nanosheets have been synthesized by a hightemperature organic solution-phase method. The thickness of VSe_(2) nanosheets can be tuned from 12 to 5 layers by dec...Two-dimensional(2 D)few-layerVSe_(2),V_(1-x)Fe_(x)Se_(2) nanosheets have been synthesized by a hightemperature organic solution-phase method. The thickness of VSe_(2) nanosheets can be tuned from 12 to 5 layers by decreasing the precursor concentrations. The few-layer VSe_(2) nanosheets show the room-temperature ferromagnetism. The coercivity and magnetization reach 0.024 T and 0.036 mA·m^(2)·g^(-1) at room temperature. The chargedensity wave behavior is also confirmed in VSe_(2) by the hysteresis loops and zero-field-cooling curve. V_(1-x)Fe_(x)Se_(2) nanosheets can be obtained by doping Fe(acac)3 in the reaction process. The room-temperature coercivity and magnetization of V_(0.8)Fe_(0.2)Se_(2) nanosheets are 5 times higher than those of the pure VSe_(2) nanosheets without destroying the structures. The enhancement of magnetization is due to the coupling interaction of 3 d orbits between V and Fe atoms. Higher Fe concentration is beneficial to improve the coercivity, which is attributed to the formation of the second phase Fe3 Se4. This simple chemical preparation method can be extended to prepare the other 2 D materials.展开更多
We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods,nanoflakes,nanoplates,and microrods by a simple wet chemical method.Growth duration is found to play a crucial role in the m...We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods,nanoflakes,nanoplates,and microrods by a simple wet chemical method.Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites.In addition,growth conditions are systematically studied as a function of precursor concentration and temperature.The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction,scanning electron microscopy,and photoluminescence spectroscopy.展开更多
A silver nanostructures prepared by using chemical reduction method. The silver nanoparticles were prepared with diameters of about (20 nm). Numerous techniques had been used to study the optical, structural like the ...A silver nanostructures prepared by using chemical reduction method. The silver nanoparticles were prepared with diameters of about (20 nm). Numerous techniques had been used to study the optical, structural like the UV-Vis absorption spectrometer, Ttransmission Electron Microscopy (TEM), Field-Emission Scanning Electron microscope (FESEM), and X-ray diffraction (XRD). The practical results exhibited the absorption spectrum of the prepared nanoparticles at (357 nm), it was found that there is a relationship between the positions of the optical absorption peak and the size of the silver nanoparticles. The analysis of TEM results showed the presence of nanoparticles in the range (20 nm). The analyzing of XRD results explained the crystal structure for silver nanoparticles. It is found a cubic unit cell have a lattice constants (a = 4.0855 <span style="white-space:nowrap;">Å</span>), with the Miller indices were (111), (002), (002), and (113).展开更多
Chemical reduction method was employed to prepare nano-sized Sn2SbNi alloy composites used as anode material for rechargeable lithium ion batteries.This strategy was adopted to combine the virtues of both active/inact...Chemical reduction method was employed to prepare nano-sized Sn2SbNi alloy composites used as anode material for rechargeable lithium ion batteries.This strategy was adopted to combine the virtues of both active/inactive and active/active alloys to fabricate a Sn2SbNi alloy powder with two active components and one inactive component.The two active components can realize the high capacity feature of electrode and can make the volume change of electrode take place in a stepwise manner due to the different lithiation potentials of two active components,leading to a stable cycling performance.Sn2SbNi alloy provides a reversible specific capacity over 640 mA·h/g with an excellent cyclic ability.The Sn-Sb-Ni alloy composite material shows to be a good candidate anode material for the lithium ion batteries.展开更多
Nanoparticles of Fe<sub>3</sub>O<sub>4</sub> and Fe are chemically synthesized by reduction of Fe(acac)<sub>3</sub> using ascorbic acid in controlled condition. It was observed that...Nanoparticles of Fe<sub>3</sub>O<sub>4</sub> and Fe are chemically synthesized by reduction of Fe(acac)<sub>3</sub> using ascorbic acid in controlled condition. It was observed that addition of water during the chemical synthesis process yields Fe3O4 nanoparticles, whereas if the reaction is carried out in absence of water yields Fe nanoparticles—which get oxidized upon exposure to air atmosphere. Fe<sub>3</sub>O<sub>4</sub> (15 ± 5 nm) and Fe/iron oxide nanoparticles (7 ± 1 nm) were successfully synthesized in the comparative study reported herewith. Mechanism for formation/synthesis of Fe<sub>3</sub>O<sub>4</sub> and Fe/iron oxide nanoparticles is proposed herewith in which added water acts as an oxygen supplier. Physico-chemical characterization done by SEM, TEM, EDAX, and XPS supports the proposed mechanism.展开更多
Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultravi...Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultraviolet-visible(UV-Vis)absorption spectroscopy and photoluminescence(PL)spectroscopy were used to determine optical properties of Cd S:Mn nanoparticles.Size quantization effect was observed in UV-Vis absorption spectra.Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping Cd S nanoparticles with Mn element.Orange emission was observed at wavelength~630 nm due to ^(4)T_1→^(6)A_1 transition.Isolated Mn~(2+)ions arranged in tetrahedral coordination are mainly responsible for luminescence.Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of Cd S nanoparticles were also discussed.The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy(AAS).Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction(XRD)technique.Cd S:Mn nanoparticles show ferromagnetism at room temperature.Transmission electron microscopy(TEM)images show spherical clusters of various sizes and selected area electron diffraction(SAED)patterns show the polycrystalline nature of the clusters.The electronic states of diluted magnetic semiconductors(DMS)ofⅡ-Ⅵgroup Cd S nanoparticles give them great potential for applications due to quantum confinement.In this study,experimental results and discussions on these aspects have been given.展开更多
Y_(2)O_(3)-doped tungsten(W-Y_(2)O_(3))composite powders prepared by a traditional chemical co-precipitation method possess obvious bimodal distribution in size,which would deteriorate their sintering properties.The b...Y_(2)O_(3)-doped tungsten(W-Y_(2)O_(3))composite powders prepared by a traditional chemical co-precipitation method possess obvious bimodal distribution in size,which would deteriorate their sintering properties.The bimodal distribution can be effectively eliminated by an improved chemical co-precipitation method,in which the cationic surfactant cetyltrimethyl-ammonium bromide(CTAB)was innovatively employed.The reduced powders with excellent uniformity have an average grain size of only~31.5 nm.It is noteworthy that Y_(2)O_(3)particles would fuse and grow with the growth of W grains during subsequent spark plasma sintering(SPS)process,which was rarely reported in relevant literature before.On top of that,phase interfaces of sintered W-Y_(2)O_(3)alloys were systematically analyzed.Compared to the intracrystalline oxygen content,the oxygen content at W/Y_(2)O_(3)phase boundaries is relatively higher.It can be found that the(110)crystal planes of W form coherent,semi-coherent,and non-coherent interfaces with different crystal planes of Y_(2)O_(3).The weak interfacial bonding strength between W and Y_(2)O_(3)phases results from relatively more oxygen impurities as well as more semi-coherent/non-coherent interfaces at phase boundaries compared with the inner W grains.展开更多
Quasi-one-dimensional ZrS_(3)nanoflakes attract intense interest attributed to their superior electrical and optical anisotropy,stemming from the low symmetry in the crystal structure.However,the conventional chemical...Quasi-one-dimensional ZrS_(3)nanoflakes attract intense interest attributed to their superior electrical and optical anisotropy,stemming from the low symmetry in the crystal structure.However,the conventional chemical vapor transport method for synthesizing bulk ZrS_(3)is limited by morphology and size controllability.It is highly desirable to propose a facile way to precisely synthesize ZrS_(3)nanoflakes.In this work,the chemical vapor deposition method is proposed as a feasible way to synthesize ZrS_(3)nanoflakes.The effects of various substrates and temperatures on ZrS_(3)synthesis have been investigated.For the as-grown ZrS_(3),good crystallinity is confirmed with X-ray diffraction and transmission electron microscopy.The structure and interlayer coupling are investigated with Raman scattering spectroscopy.The strong in-plane anisotropy and interlayer coupling of the ZrS_(3)nanoflakes are illustrated with angle-resolved Raman spectroscopy and temperature-dependent Raman characterization,respectively.This study demonstrates a feasible way for the synthesis of transition metal trisulfides,which may shed new light on the research of other two-dimensional anisotropic transition metal materials.展开更多
Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showe...Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption(NLA) coefficient and the value of nonlinear refraction(NLR) index of the products increased from 0 to 3.167 cm/GW and from 0.64×10 4 to 6.83×10 4 cm 2 /GW,respectively.展开更多
In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was ...In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.展开更多
Nano metal materials have been widely explored to be applied in medical,environmental,and material science.Among these nanoparticles,especially silver nanoparticles(AgNPs),have drawn increasing attention for antimicro...Nano metal materials have been widely explored to be applied in medical,environmental,and material science.Among these nanoparticles,especially silver nanoparticles(AgNPs),have drawn increasing attention for antimicrobial applications.Most researchers are keen on the development of the biologically friendly capping reagents for the synthesis of AgNPs,instead of unfriendly organic polymers.In this study,the liquid chemical reduction method was used to synthesize AgNPs with edible whey protein isolate(WPI)as a capping reagent.These WPI-AgNPs had a broad size distribution(average diameter of 138.6 nm),and their dimensions could be readily controlled in the range of 22.5-149.6 nm by introducing different concentrations of chloride.Subsequently,it was confirmed that WPI-AgNPs were formed through two mechanisms,which were respectively reduced in situ(without the addition of NaCl)and ex situ(in presence of NaCl)to yield silver nanoparticles.The WPI-AgNPs synthesized in presence of 10 mM of NaCl as mediation reagent were stable at room temperature or 4℃ up to 3 months.Furthermore,the synthesized WPI-AgNPs had a good antibacterial activity toward pathogens including Gram-negative E.coli and Gram-positive S.aureus.The results shed light on method and capping reagent to stabilize silver nanoparticles,which highlighted the potential of WPI and chloride in metal nanoparticle synthesis.展开更多
Among various metal chalcogenides,metal oxides and phases of copper sulfide,copper(Ⅱ)sulfide(covellite,CuS)nanostructures have enjoyed special attentiveness from researchers and scientists across the world owing to t...Among various metal chalcogenides,metal oxides and phases of copper sulfide,copper(Ⅱ)sulfide(covellite,CuS)nanostructures have enjoyed special attentiveness from researchers and scientists across the world owing to their complicated structure,peculiar composition and valency,attractive and panoramic morphologies,optical and electrical conductivity,less toxicity,and biocompatibility that can be exploited in advanced and technological applications.This review paper presents a brief idea about crystal structure,composition,and various chemical methods.The mechanism and effect of reaction parameters on the evolution of versatile and attractive morphologies have been described.Physical properties of CuS and its hybrid nanostructures,such as morphology and optical,mechanical,electrical,thermal,and thermoelectrical properties,have been carefully reviewed.A concise account of CuS and its hybrid nanostructures’diverse applications in emerging and recent applications such as energy storage devices(lithium-ion batteries,supercapacitance),sensors,field emission,photovoltaic cells,organic pollutant removal,electromagnetic wave absorption,and emerging biomedical field(drug delivery,photothermal ablation,deoxyribonucleic acid detection,anti-microbial and theranostic)has also been elucidated.Finally,the prospects,scope,and challenges of CuS nanostructures have been discussed precisely.展开更多
A total of 168 PM_(10)samples were collected during the year of 2005 at eight sites in the city of Wuxi in China.Fifteen chemical elements,three water-soluble ions,total carbon and organic carbon were analyzed.Six sou...A total of 168 PM_(10)samples were collected during the year of 2005 at eight sites in the city of Wuxi in China.Fifteen chemical elements,three water-soluble ions,total carbon and organic carbon were analyzed.Six source categories were identified and their contributions to ambient PM_(10)in Wuxi were estimated using a nested chemical mass balance method that reduces the effects of colinearity on the chemical mass balance model.In addition,the concentrations of secondary aerosols,such as secondary organic carbon,sulfate and nitrate,were quantified.The spatially averaged PM_(10)was high in the spring and winter(123μg·m^(-3)and low in the summer-fall(90μg·m^(-3)).According to the result of source apportionment,resuspended dust was the largest contributor to ambient PM_(10),accounting for more than 50%of the PM_(10)mass.Coal combustion(14.6%)and vehicle exhaust(9.4%)were also significant source categories of ambient PM_(10).Construction and cement dust,sulfates,secondary organic carbon,and nitrates made contributions ranging between 4.1%and 4.9%.Other source categories such as steel manufacturing dust and soil dust made low contributions to ambient PM_(10).展开更多
Ultraviolet(UV)nonlinear optical(NLO)crystal materials are hailed as the"chip"of the optoelectronic industry for they play a unique and crucial role in many newly developed scientific and technological appli...Ultraviolet(UV)nonlinear optical(NLO)crystal materials are hailed as the"chip"of the optoelectronic industry for they play a unique and crucial role in many newly developed scientific and technological applications.At present,due to the relatively single frequency doubling gene types of traditional NLO materials,the service performance of UV NLO materials is fundamentally restricted.Therefore,there is an urgent need to develop new synthesis methods,search for novel functional groups,expand new UV NLO materials systems,screen new high-performance crystals,and then break through performance bottlenecks.Herein,we review the recent progresses on UV NLO crystal materials.Furthermore,we prospect that these recently developed approaches will continuously extend their advantages in developing superior UV NLO materials in the near future.展开更多
Nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite was prepared by chemical co-precipitation method.The samples were characterized by X-ray diffraction(XRD),field-emission transmission electron microscopy(FETEM),vibrating ...Nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite was prepared by chemical co-precipitation method.The samples were characterized by X-ray diffraction(XRD),field-emission transmission electron microscopy(FETEM),vibrating sample magnetometer(VSM)and network analyzer.TEM analysis indicates that the diameter of as-prepared powder is about 20-30 nm.The saturation magnetization of nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite is 74.01 mA·m^(2)·g^(−1).The complex permittivity and complex permeability of the Co-Zn ferrite were measured by vector network analyzer in the frequency range of 2.0-18.0 GHz,and the reflection loss(RL)was investigated according to the wave transmission theory.The results show that the maximum reflection loss reaches−13.7 dB at 6.8 GHz and the bandwidth of reflection loss less than−10 dB reaches 3.8 GHz.The as-prepared nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite can be potentially used as an excellent microwave absorber in the C-band.展开更多
The interaction parameters of Nb in Fe-C-Nb melts at 1873 K were measured using the chemical equilibrium method.The Fe-C melts were equilibrated with the CaO-MgO-Al_(2)O_(3)-NbO_(2) slags under a controlled oxygen pot...The interaction parameters of Nb in Fe-C-Nb melts at 1873 K were measured using the chemical equilibrium method.The Fe-C melts were equilibrated with the CaO-MgO-Al_(2)O_(3)-NbO_(2) slags under a controlled oxygen potential for 24 h.In addition to acting as the protective gas,argon was adopted to control the oxygen potential.Based on the data obtained in the experiments,the activity interaction parameters were obtained by the multiple linear regression method.The first-order interaction parameters e_(Nb)^(C)and e_(Nb)^(Nb)are determined to be−0.035 and−0.134,respectively.The second-order interaction parameters r_(Nb)^(C),r_(Nb)^(Nb,C),and r_(Nb)……(Nb)are determined to be 0.011,−0.0063,and 0.0023,respectively.The thermodynamic data obtained are more reliable than those in previous publications for the Fe-C-Nb system when the Nb content range was 0.92-4.62 wt.%.展开更多
基金financially supported by the ITER-National Magnetic Confinement Fusion Program(No.2014GB123000)。
文摘In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structure were prepared by an improved wet chemical method at different reaction temperature conditions.Consequently,fine platelike precursor(200-400 nm)and flower-like precursor(approximately 1.25μm)are obtained.After reduction and sintering,the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy.In the sample sintered from the platelike precursor,TiC particles with sizes in the range of40-300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors.However,in the sample sintered from the flower-like precursor,the TiC particles with sizes in the range of 50-700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix.As a result,the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor.The average bending strength of the sample sintered from the plate-like precursor is 655 MPa,which is higher than that of the sample sintered from the flower-like precursor(524 MPa).Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.
基金financially supported by the National Natural Science Foundation of China(Nos.51971122,51571135 and 51701106)the National Key R&D Program of China(No.2017YFB0405703)。
文摘Two-dimensional(2 D)few-layerVSe_(2),V_(1-x)Fe_(x)Se_(2) nanosheets have been synthesized by a hightemperature organic solution-phase method. The thickness of VSe_(2) nanosheets can be tuned from 12 to 5 layers by decreasing the precursor concentrations. The few-layer VSe_(2) nanosheets show the room-temperature ferromagnetism. The coercivity and magnetization reach 0.024 T and 0.036 mA·m^(2)·g^(-1) at room temperature. The chargedensity wave behavior is also confirmed in VSe_(2) by the hysteresis loops and zero-field-cooling curve. V_(1-x)Fe_(x)Se_(2) nanosheets can be obtained by doping Fe(acac)3 in the reaction process. The room-temperature coercivity and magnetization of V_(0.8)Fe_(0.2)Se_(2) nanosheets are 5 times higher than those of the pure VSe_(2) nanosheets without destroying the structures. The enhancement of magnetization is due to the coupling interaction of 3 d orbits between V and Fe atoms. Higher Fe concentration is beneficial to improve the coercivity, which is attributed to the formation of the second phase Fe3 Se4. This simple chemical preparation method can be extended to prepare the other 2 D materials.
文摘We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods,nanoflakes,nanoplates,and microrods by a simple wet chemical method.Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites.In addition,growth conditions are systematically studied as a function of precursor concentration and temperature.The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction,scanning electron microscopy,and photoluminescence spectroscopy.
文摘A silver nanostructures prepared by using chemical reduction method. The silver nanoparticles were prepared with diameters of about (20 nm). Numerous techniques had been used to study the optical, structural like the UV-Vis absorption spectrometer, Ttransmission Electron Microscopy (TEM), Field-Emission Scanning Electron microscope (FESEM), and X-ray diffraction (XRD). The practical results exhibited the absorption spectrum of the prepared nanoparticles at (357 nm), it was found that there is a relationship between the positions of the optical absorption peak and the size of the silver nanoparticles. The analysis of TEM results showed the presence of nanoparticles in the range (20 nm). The analyzing of XRD results explained the crystal structure for silver nanoparticles. It is found a cubic unit cell have a lattice constants (a = 4.0855 <span style="white-space:nowrap;">Å</span>), with the Miller indices were (111), (002), (002), and (113).
基金Project(2008cd148)supported by the Social Development Plan of Yunnan Province,ChinaProject(2010)supported by Key Science and Technology Fund of Education Department,China
文摘Chemical reduction method was employed to prepare nano-sized Sn2SbNi alloy composites used as anode material for rechargeable lithium ion batteries.This strategy was adopted to combine the virtues of both active/inactive and active/active alloys to fabricate a Sn2SbNi alloy powder with two active components and one inactive component.The two active components can realize the high capacity feature of electrode and can make the volume change of electrode take place in a stepwise manner due to the different lithiation potentials of two active components,leading to a stable cycling performance.Sn2SbNi alloy provides a reversible specific capacity over 640 mA·h/g with an excellent cyclic ability.The Sn-Sb-Ni alloy composite material shows to be a good candidate anode material for the lithium ion batteries.
文摘Nanoparticles of Fe<sub>3</sub>O<sub>4</sub> and Fe are chemically synthesized by reduction of Fe(acac)<sub>3</sub> using ascorbic acid in controlled condition. It was observed that addition of water during the chemical synthesis process yields Fe3O4 nanoparticles, whereas if the reaction is carried out in absence of water yields Fe nanoparticles—which get oxidized upon exposure to air atmosphere. Fe<sub>3</sub>O<sub>4</sub> (15 ± 5 nm) and Fe/iron oxide nanoparticles (7 ± 1 nm) were successfully synthesized in the comparative study reported herewith. Mechanism for formation/synthesis of Fe<sub>3</sub>O<sub>4</sub> and Fe/iron oxide nanoparticles is proposed herewith in which added water acts as an oxygen supplier. Physico-chemical characterization done by SEM, TEM, EDAX, and XPS supports the proposed mechanism.
文摘Manganese(Mn)doped cadmium sulphide(Cd S)nanoparticles were synthesized using a chemical method.It was possible to decrease Cd S:Mn particle size by increasing Mn concentration.Investigation techniques such as ultraviolet-visible(UV-Vis)absorption spectroscopy and photoluminescence(PL)spectroscopy were used to determine optical properties of Cd S:Mn nanoparticles.Size quantization effect was observed in UV-Vis absorption spectra.Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping Cd S nanoparticles with Mn element.Orange emission was observed at wavelength~630 nm due to ^(4)T_1→^(6)A_1 transition.Isolated Mn~(2+)ions arranged in tetrahedral coordination are mainly responsible for luminescence.Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of Cd S nanoparticles were also discussed.The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy(AAS).Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction(XRD)technique.Cd S:Mn nanoparticles show ferromagnetism at room temperature.Transmission electron microscopy(TEM)images show spherical clusters of various sizes and selected area electron diffraction(SAED)patterns show the polycrystalline nature of the clusters.The electronic states of diluted magnetic semiconductors(DMS)ofⅡ-Ⅵgroup Cd S nanoparticles give them great potential for applications due to quantum confinement.In this study,experimental results and discussions on these aspects have been given.
基金the National Natural Science Foundation of China(Grant Nos.51822404 and 51574178)the Science and Technology Program of Tianjin(Grant No.18YFZCGX00070)+1 种基金the Natural Science Foundation of Tianjin(Grant No.18JCYBJC17900)the Seed Foundation of Tianjin University(Grant Nos.2018XRX-0005 and 2019XYF-0066).
文摘Y_(2)O_(3)-doped tungsten(W-Y_(2)O_(3))composite powders prepared by a traditional chemical co-precipitation method possess obvious bimodal distribution in size,which would deteriorate their sintering properties.The bimodal distribution can be effectively eliminated by an improved chemical co-precipitation method,in which the cationic surfactant cetyltrimethyl-ammonium bromide(CTAB)was innovatively employed.The reduced powders with excellent uniformity have an average grain size of only~31.5 nm.It is noteworthy that Y_(2)O_(3)particles would fuse and grow with the growth of W grains during subsequent spark plasma sintering(SPS)process,which was rarely reported in relevant literature before.On top of that,phase interfaces of sintered W-Y_(2)O_(3)alloys were systematically analyzed.Compared to the intracrystalline oxygen content,the oxygen content at W/Y_(2)O_(3)phase boundaries is relatively higher.It can be found that the(110)crystal planes of W form coherent,semi-coherent,and non-coherent interfaces with different crystal planes of Y_(2)O_(3).The weak interfacial bonding strength between W and Y_(2)O_(3)phases results from relatively more oxygen impurities as well as more semi-coherent/non-coherent interfaces at phase boundaries compared with the inner W grains.
基金S.L.acknowledges the financial support from the National Natural Science Foundation of China(Nos.22175060 and 21975067)the Natural Science Foundation of Hunan Province of China(Nos.2021JJ10014 and 2021JJ30092)。
文摘Quasi-one-dimensional ZrS_(3)nanoflakes attract intense interest attributed to their superior electrical and optical anisotropy,stemming from the low symmetry in the crystal structure.However,the conventional chemical vapor transport method for synthesizing bulk ZrS_(3)is limited by morphology and size controllability.It is highly desirable to propose a facile way to precisely synthesize ZrS_(3)nanoflakes.In this work,the chemical vapor deposition method is proposed as a feasible way to synthesize ZrS_(3)nanoflakes.The effects of various substrates and temperatures on ZrS_(3)synthesis have been investigated.For the as-grown ZrS_(3),good crystallinity is confirmed with X-ray diffraction and transmission electron microscopy.The structure and interlayer coupling are investigated with Raman scattering spectroscopy.The strong in-plane anisotropy and interlayer coupling of the ZrS_(3)nanoflakes are illustrated with angle-resolved Raman spectroscopy and temperature-dependent Raman characterization,respectively.This study demonstrates a feasible way for the synthesis of transition metal trisulfides,which may shed new light on the research of other two-dimensional anisotropic transition metal materials.
基金Supported by the National Natural Science Foundation of China(11174229)
文摘Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption(NLA) coefficient and the value of nonlinear refraction(NLR) index of the products increased from 0 to 3.167 cm/GW and from 0.64×10 4 to 6.83×10 4 cm 2 /GW,respectively.
基金This paper was supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20191019)the Natural Science Research Project in Colleges and Universities in Jiangsu Province of China(Grant No.19KJB470022)+1 种基金the Scientific Research Start-up Foundation funding of High-level Introduction Talents of Nanjing Institute of Technology(Grant No.YKJ201912)the Open Fund Project of the Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education of Southeast University.
文摘In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.
基金This work was supported by National Key Research and Development Program of China(2017YFC1601704)National Natural Science Foundation of China(31522044,31671909,31772034,and 31901630)+4 种基金Program of Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment&Technology(FMZ201904)National First-class Discipline Program of Food Science and Technology(JUFSTR20180205)Natural Science Foundation of Jiangsu Province-Youth Program(BK20190583)Fundamental Research Funds for the Central Universities(JUSRP12007)Jiangsu Planned Projects for Postdoctoral Research Funds(2020Z047).
文摘Nano metal materials have been widely explored to be applied in medical,environmental,and material science.Among these nanoparticles,especially silver nanoparticles(AgNPs),have drawn increasing attention for antimicrobial applications.Most researchers are keen on the development of the biologically friendly capping reagents for the synthesis of AgNPs,instead of unfriendly organic polymers.In this study,the liquid chemical reduction method was used to synthesize AgNPs with edible whey protein isolate(WPI)as a capping reagent.These WPI-AgNPs had a broad size distribution(average diameter of 138.6 nm),and their dimensions could be readily controlled in the range of 22.5-149.6 nm by introducing different concentrations of chloride.Subsequently,it was confirmed that WPI-AgNPs were formed through two mechanisms,which were respectively reduced in situ(without the addition of NaCl)and ex situ(in presence of NaCl)to yield silver nanoparticles.The WPI-AgNPs synthesized in presence of 10 mM of NaCl as mediation reagent were stable at room temperature or 4℃ up to 3 months.Furthermore,the synthesized WPI-AgNPs had a good antibacterial activity toward pathogens including Gram-negative E.coli and Gram-positive S.aureus.The results shed light on method and capping reagent to stabilize silver nanoparticles,which highlighted the potential of WPI and chloride in metal nanoparticle synthesis.
基金the Sardar Patel University,Mandi,Himachal Pradesh,India-175001 and Government College,Nadaun,District Hamirpur,Himachal Pradesh,India-177033 for unwavering support and moral support during data analysis and compilation.
文摘Among various metal chalcogenides,metal oxides and phases of copper sulfide,copper(Ⅱ)sulfide(covellite,CuS)nanostructures have enjoyed special attentiveness from researchers and scientists across the world owing to their complicated structure,peculiar composition and valency,attractive and panoramic morphologies,optical and electrical conductivity,less toxicity,and biocompatibility that can be exploited in advanced and technological applications.This review paper presents a brief idea about crystal structure,composition,and various chemical methods.The mechanism and effect of reaction parameters on the evolution of versatile and attractive morphologies have been described.Physical properties of CuS and its hybrid nanostructures,such as morphology and optical,mechanical,electrical,thermal,and thermoelectrical properties,have been carefully reviewed.A concise account of CuS and its hybrid nanostructures’diverse applications in emerging and recent applications such as energy storage devices(lithium-ion batteries,supercapacitance),sensors,field emission,photovoltaic cells,organic pollutant removal,electromagnetic wave absorption,and emerging biomedical field(drug delivery,photothermal ablation,deoxyribonucleic acid detection,anti-microbial and theranostic)has also been elucidated.Finally,the prospects,scope,and challenges of CuS nanostructures have been discussed precisely.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20877042)National Science and Technology Supporting Program during the Eleventh Five-year Plan Period(No.2007BAC16B01).
文摘A total of 168 PM_(10)samples were collected during the year of 2005 at eight sites in the city of Wuxi in China.Fifteen chemical elements,three water-soluble ions,total carbon and organic carbon were analyzed.Six source categories were identified and their contributions to ambient PM_(10)in Wuxi were estimated using a nested chemical mass balance method that reduces the effects of colinearity on the chemical mass balance model.In addition,the concentrations of secondary aerosols,such as secondary organic carbon,sulfate and nitrate,were quantified.The spatially averaged PM_(10)was high in the spring and winter(123μg·m^(-3)and low in the summer-fall(90μg·m^(-3)).According to the result of source apportionment,resuspended dust was the largest contributor to ambient PM_(10),accounting for more than 50%of the PM_(10)mass.Coal combustion(14.6%)and vehicle exhaust(9.4%)were also significant source categories of ambient PM_(10).Construction and cement dust,sulfates,secondary organic carbon,and nitrates made contributions ranging between 4.1%and 4.9%.Other source categories such as steel manufacturing dust and soil dust made low contributions to ambient PM_(10).
基金Supported by National Natural Science Foundation of China(21971171,21875146)。
文摘Ultraviolet(UV)nonlinear optical(NLO)crystal materials are hailed as the"chip"of the optoelectronic industry for they play a unique and crucial role in many newly developed scientific and technological applications.At present,due to the relatively single frequency doubling gene types of traditional NLO materials,the service performance of UV NLO materials is fundamentally restricted.Therefore,there is an urgent need to develop new synthesis methods,search for novel functional groups,expand new UV NLO materials systems,screen new high-performance crystals,and then break through performance bottlenecks.Herein,we review the recent progresses on UV NLO crystal materials.Furthermore,we prospect that these recently developed approaches will continuously extend their advantages in developing superior UV NLO materials in the near future.
基金financially supported by the National Natural Science Foundation of China(Nos.51402154,51202111)the Natural Science Foundation of Jiangsu Province(No.BK20141000)+1 种基金the Natural Science Foundation of Jiangsu Provincial Universities(No.14KJB430019)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite was prepared by chemical co-precipitation method.The samples were characterized by X-ray diffraction(XRD),field-emission transmission electron microscopy(FETEM),vibrating sample magnetometer(VSM)and network analyzer.TEM analysis indicates that the diameter of as-prepared powder is about 20-30 nm.The saturation magnetization of nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite is 74.01 mA·m^(2)·g^(−1).The complex permittivity and complex permeability of the Co-Zn ferrite were measured by vector network analyzer in the frequency range of 2.0-18.0 GHz,and the reflection loss(RL)was investigated according to the wave transmission theory.The results show that the maximum reflection loss reaches−13.7 dB at 6.8 GHz and the bandwidth of reflection loss less than−10 dB reaches 3.8 GHz.The as-prepared nanosized Co_(0.5)Zn_(0.5)Fe_(2)O_(4) ferrite can be potentially used as an excellent microwave absorber in the C-band.
基金support of this research by the National Natural Science Foundation of China(Grant Nos.51774025,51534001)Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-20-009A1).
文摘The interaction parameters of Nb in Fe-C-Nb melts at 1873 K were measured using the chemical equilibrium method.The Fe-C melts were equilibrated with the CaO-MgO-Al_(2)O_(3)-NbO_(2) slags under a controlled oxygen potential for 24 h.In addition to acting as the protective gas,argon was adopted to control the oxygen potential.Based on the data obtained in the experiments,the activity interaction parameters were obtained by the multiple linear regression method.The first-order interaction parameters e_(Nb)^(C)and e_(Nb)^(Nb)are determined to be−0.035 and−0.134,respectively.The second-order interaction parameters r_(Nb)^(C),r_(Nb)^(Nb,C),and r_(Nb)……(Nb)are determined to be 0.011,−0.0063,and 0.0023,respectively.The thermodynamic data obtained are more reliable than those in previous publications for the Fe-C-Nb system when the Nb content range was 0.92-4.62 wt.%.
