W-Y2O3 composite nanopowders prepared via wet chemical method exhibit unique morphologies and micro structures.The yttrium addition during chemical reaction process affects not only the composition of tungsten acid hy...W-Y2O3 composite nanopowders prepared via wet chemical method exhibit unique morphologies and micro structures.The yttrium addition during chemical reaction process affects not only the composition of tungsten acid hydrate precursors,but also the reduction property of tungsten oxide transformed from precursors.In this study,the morphology evolution of the samples with and without yttrium during reduction process has been studied,and it is found that the addition of yttrium can exert a strong influence on the reduction route of tungsten oxide and the final morphology of tungsten particles.The cause of the difference of reduction route and tungsten particle morphology is also analyzed.It is suggested that the composition of the samples with yttrium at the beginning of reduction is pure cubic system WO3(c-WO3),and the c-WO3 particles have c-WO3 whiskers attached to the surface.This kind of whiskers is essential for c-WO3 to be reduced directly to tungsten and also helpful to obtain W-Y2O3 powders with small size and good uniformity.展开更多
As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical advantages.Ascertaining the synthesis m...As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical advantages.Ascertaining the synthesis mechanism behind wet chemical method is indispensable for controlled synthesis of highquality W-Y2 O3 composite powder precursor.The co-deposition mechanism of yttrium and tungsten component behind the wet chemical method of preparing yttrium-doped tungsten composite nanopowder was investigated systematically in this work.A series of co-deposited composite powders fabricated under different acidity conditions were used as research targets for investigating the effect of surface composition and structure on co-deposition efficiency.It was found that white tungstic acid has more W-OH bonds and much higher co-deposition efficiency with Y^3+ions than yellow tungstic acid.It is illustrated that the coordination reaction between W-OH bonds on tungstic acid particles and Y^3+ions brings the co-deposition of yttrium and tungsten component into being.Through displacing H^+ions in W-OH bonds,Y^3+ions can be adsorbed on the surface of or incorporated into tungstic acid particles in form of ligand.Consequently,to control and regulate Y2 O3 content in powder precursor accurately,H^+ion concentration in wet chemical reaction should be in range of 0.55-2.82 mol L^-1 to obtain white tungstic acid.Besides,H^+ion concentration also has prominent effect on the grain size and morphology of reduced powder precursor.The optimal value should be around 1.58 mol L^-1,which can lead to minimum W grain size(about 17 nm) without bimodal structure.The chemical mechanism proposed in this work could produce great sense to preparation of high-quality precursor for sintering high-performance Y2 O3 dispersion strengthened W based alloys.Our work may also shed light on the approach to exploit analogous synthesis mechanism in other alloy systems.展开更多
Bismuth-doped tin dioxide （BTO） nanometer powders were prepared by the wet chemical method using tin tetrachloride （SnCl4）, bismuth nitrate [Bi（NO3） 3 ] and ammonia as raw materials. Non-bridge hydroxides and ca...Bismuth-doped tin dioxide （BTO） nanometer powders were prepared by the wet chemical method using tin tetrachloride （SnCl4）, bismuth nitrate [Bi（NO3） 3 ] and ammonia as raw materials. Non-bridge hydroxides and capillary force between particles were found to be key factors causing hard aggregation of BTO through analyzing the formation mechanism of hard aggregation. The hard aggregation of BTO was eliminated effectively when the Bi-Sn precursor （BSP） was treated with post processing including dispersing with ultrasonic wave, refluxing and distilling with addition of n-butanol and benzene （DRD） and drying by microwave. Characterized with X-ray diffraction （XRD） and transmission electron microscopy （TEM）, BTO spherical particles with tetragonal phase structure are well crystallized, dispersed easily and the average size was less than 10 nm.展开更多
The large-scale ZnO rods of submicrometer were prepared on the bare glass using a wet chemical method under different experimental parameters,such as the reactant concentration and the growth time.The microstructure o...The large-scale ZnO rods of submicrometer were prepared on the bare glass using a wet chemical method under different experimental parameters,such as the reactant concentration and the growth time.The microstructure of the ZnO rods was characterized by X-ray diffractometry(XRD) and field emission scanning electron microscopy (FESEM) with the energy dispersive X-ray spectroscopy(EDX),and the optical property was investigated by the room-temperature photoluminescence (PL) spectra.XRD and FESEM results show that the wurtzite structure and rod-like ZnO is obtained.The length (3-8 μm) and the diameter (400 nm-3 μm) vary with the experimental parameters.A strong UV emission at 384 nm and a weak visible yellow-green emission around 570 nm are observed in the PL spectrum.After annealing at 600 ℃ in air,the UV peak intensity increases obviously and the yellow-green peak intensity decreases greatly.The near-band-edge UV emission is attributed to the exciton recombination; the yellow-green emission can be associated with the defect recombination; and some defect complexes may be responsible for the latter emission.展开更多
A modified wet chemical route for low-temperature synthesis of the calcium stannate CaSnO3, a potentialmaterial for dielectric applications is reported. Firstly, a precursor CaSn(OH)6 was prepared using tin tetrachlor...A modified wet chemical route for low-temperature synthesis of the calcium stannate CaSnO3, a potentialmaterial for dielectric applications is reported. Firstly, a precursor CaSn(OH)6 was prepared using tin tetrachloride,calcium chloride and sodium hydroxide at room temperature. Then the precursor was annealed at relatively low tem-perature of 600 ℃ to obtain CaSnO3. The phase identification, thermal behavior and surface morphology of the sam-ples were characterized by element analysis, X-ray diffraction (XRD), thermo-gravimetric (TG) analysis and deriva-tive thermo-gravimetric (DTG) analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron mi-croscopy (SEM) in detail. The results show that CaSnO3 obtained by this method possesses a cubic perovskitestructure with average grain size of 5 μm.展开更多
A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate sol...A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate solution with silver nitrate solution at the presence of different modifiers with high-speed stirring at 8-20℃. It is found that the diameters of resulting products are 0.6-6.0 um and the morphologies of the silver microcrystals are greatly affected by the introduced modifiers. It is concluded that the microsized silver crystals with different morphologies can be synthesized by introducing appropriate modifiers at appropriate experimental parameters. Scanning electron microscopy and X-ray diffraction were used to characterize the resulting products.展开更多
A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape fac...A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape factors of the ＂slot＂ and the preset depth used in ＂wetting-drying＂ algorithm. Two typical tests are conducted to examine the performance of the method with the effect of the shape factors of the ＂slot＂ being checked in detail in the first test. Numerical results demonstrate that： 1 ） no additional effort to improve the finite difference scheme is needed to implement ＂slot method＂ in DIVAST, and 2） ＂slot method＂ will simulate wetting and diying processes correctly if the shape factors of the ＂slot＂ being selected properly.展开更多
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
To prepare PZT powder at lower temperature, lead zirconate titanate (PZT) powder (x(Zr)/x(Ti)=56?44) was prepared by wet-dry method. Glycol was used as the solvent, and zirconium oxychloride was used as zirconium sour...To prepare PZT powder at lower temperature, lead zirconate titanate (PZT) powder (x(Zr)/x(Ti)=56?44) was prepared by wet-dry method. Glycol was used as the solvent, and zirconium oxychloride was used as zirconium source. The properties and structure of the powder were analyzed by XRD, SEM and Sedimentograph. The effects of sintering parameter such as sintering temperature, keeping time and heating-up velocity on structure of PZT power were investigated. The results show that homogeneous PZT with single-phase perovskite structure can be obtained after sintering at 730 ℃ for 2 h, and the average size of PZT powder is about 113 nm.展开更多
The wetting behavior of liquid tin(Sn)solder on copper(Cu)substrate at 250℃was investigated by the wetting balance method under the action of direct current(DC).The curves of wetting balance were measured and the mor...The wetting behavior of liquid tin(Sn)solder on copper(Cu)substrate at 250℃was investigated by the wetting balance method under the action of direct current(DC).The curves of wetting balance were measured and the morphology of the intermetallic compound(IMC)precipitated at the interface were observed.Results show that DC has a significant effect on the wettability and IMC.As the current increases,the balance wetting force and the thickness of the IMC layer increase.The direction of the DC also has a certain effect on the balance wetting force and IMC layer.When the current is negative,the final balance wetting force and the thickness of the Cu_(6)Sn_(5) layer are significantly higher than those in the positive current case,which is attributed to electromigration.The IMC precipitation at the interface provides a chemical driving force for the movement of the triple junction.The interaction of the interface atoms and the chemical reaction are enhanced by DC,thereby improving wettability.Meanwhile,the Marangoni convection caused by DC inside liquid Sn solder changes the structure of triple junction,which provides a physical driving force for the spread of the liquid Sn solder on the Cu substrate.展开更多
Soil surface wetness is indispensable land surface parameter in agriculture, hydrology and environmental engineering. This paper explores the relationship between surface radiant temperature and fractional vegetation ...Soil surface wetness is indispensable land surface parameter in agriculture, hydrology and environmental engineering. This paper explores the relationship between surface radiant temperature and fractional vegetation cover derived from satellite imagery to estimate soil surface wetness (triangle method) in Allahabad district. The pixel distributions create triangular shapes because the range of surface radiant temperature decreases as the amount of vegetation cover increases and sufficient number of pixels exists. A very weak correlation is found between the simulated soil surface wetness and ground measured soil moisture at deeper soil layers (R<sup>2</sup> < 0.15) on all the dates under investigation. This is because the drying rates at the surface discontinue to be linearly correlated to that at lower levels (depths). The standing water pixels distort the shape of the triangle especially at lower left edge of the triangle. This distortion is removable. The spatial and temporal inhomogeneity of soil surface wetness is examined.展开更多
Rechargeable aqueous Zn-ion batteries(AZIBs)are one of the most promising energy storage devices for large-scale energy storage owing to their high specific capacity,eco-friendliness,low cost and high safety.Neverthel...Rechargeable aqueous Zn-ion batteries(AZIBs)are one of the most promising energy storage devices for large-scale energy storage owing to their high specific capacity,eco-friendliness,low cost and high safety.Nevertheless,zinc metal anodes suffer from severe dendrite growth and side reactions,resulting in the inferior electrochemical performance of AZIBs.To address these problems,surface modification of zinc metal anodes is a facile and effective method to regulate the interaction between the zinc anode and an electrolyte.In this review,the current challenges and strategies for zinc metal anodes are presented.Furthermore,recent advances in surface modification strategies to improve their electrochemical performance are concluded and discussed.Finally,challenges and prospects for future development of zinc metal anodes are proposed.We hope this review will be useful for designing and fabricating highperformance AZIBs and boosting their practical applications.展开更多
An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loadi...An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loading of Ga, Al, Ag, and Ce was 0.2 wt.%, 0.002 wt.%, 0.25 wt.%, and 0.15 wt.%, respectively. Intermetallic compounds （IMCs） formed at the interface between Sn-9Zn-0.2Ga-0.002Al-0.25Ag- 0.15Ce solder and Cu substrate were investigated by scanning electron microscope （SEM） and energy dispersive spectroscopy （EDS） analysis. The SEM images illustrate that the IMCs can be divided into two portions from the substrate side to the solder side： a planar CusZns layer and an additional continuous scallop-like AgZn3 layer. The EDS analysis also shows that Ga segregates in the solder abutting upon the interface. X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES） of the surface components of Sn-9Zn-0.2Ga-0.002Al- 0.25Ag-0.15Ce solder indicate that Al aggregates at the surface in the form of Al203 protective fdm, which prevents the further oxidation of the solder surface. On the other hand, Ce aggregates at the subsurface, which may reduce the surface tension of the solder and improve the wettability in consequence.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51822404 and 51574178)the Science and Technology Program of Tianjin(No.18YFZCGX00070)+1 种基金the Natural Science Foundation of Tianjin(No.18JCYBJC17900)the Seed Foundation of Tianjin University(Nos.2018XRX-0005 and 2019XYF-0066).
文摘W-Y2O3 composite nanopowders prepared via wet chemical method exhibit unique morphologies and micro structures.The yttrium addition during chemical reaction process affects not only the composition of tungsten acid hydrate precursors,but also the reduction property of tungsten oxide transformed from precursors.In this study,the morphology evolution of the samples with and without yttrium during reduction process has been studied,and it is found that the addition of yttrium can exert a strong influence on the reduction route of tungsten oxide and the final morphology of tungsten particles.The cause of the difference of reduction route and tungsten particle morphology is also analyzed.It is suggested that the composition of the samples with yttrium at the beginning of reduction is pure cubic system WO3(c-WO3),and the c-WO3 particles have c-WO3 whiskers attached to the surface.This kind of whiskers is essential for c-WO3 to be reduced directly to tungsten and also helpful to obtain W-Y2O3 powders with small size and good uniformity.
基金supported financially by the National Natural Science Foundation of China(Nos.51574178 and 51822404)the Natural Science Foundation of Tianjin(No.18JCYBJC17900)the Seed Foundation of Tianjin University(No.2018XRX-0005)。
文摘As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical advantages.Ascertaining the synthesis mechanism behind wet chemical method is indispensable for controlled synthesis of highquality W-Y2 O3 composite powder precursor.The co-deposition mechanism of yttrium and tungsten component behind the wet chemical method of preparing yttrium-doped tungsten composite nanopowder was investigated systematically in this work.A series of co-deposited composite powders fabricated under different acidity conditions were used as research targets for investigating the effect of surface composition and structure on co-deposition efficiency.It was found that white tungstic acid has more W-OH bonds and much higher co-deposition efficiency with Y^3+ions than yellow tungstic acid.It is illustrated that the coordination reaction between W-OH bonds on tungstic acid particles and Y^3+ions brings the co-deposition of yttrium and tungsten component into being.Through displacing H^+ions in W-OH bonds,Y^3+ions can be adsorbed on the surface of or incorporated into tungstic acid particles in form of ligand.Consequently,to control and regulate Y2 O3 content in powder precursor accurately,H^+ion concentration in wet chemical reaction should be in range of 0.55-2.82 mol L^-1 to obtain white tungstic acid.Besides,H^+ion concentration also has prominent effect on the grain size and morphology of reduced powder precursor.The optimal value should be around 1.58 mol L^-1,which can lead to minimum W grain size(about 17 nm) without bimodal structure.The chemical mechanism proposed in this work could produce great sense to preparation of high-quality precursor for sintering high-performance Y2 O3 dispersion strengthened W based alloys.Our work may also shed light on the approach to exploit analogous synthesis mechanism in other alloy systems.
文摘Bismuth-doped tin dioxide （BTO） nanometer powders were prepared by the wet chemical method using tin tetrachloride （SnCl4）, bismuth nitrate [Bi（NO3） 3 ] and ammonia as raw materials. Non-bridge hydroxides and capillary force between particles were found to be key factors causing hard aggregation of BTO through analyzing the formation mechanism of hard aggregation. The hard aggregation of BTO was eliminated effectively when the Bi-Sn precursor （BSP） was treated with post processing including dispersing with ultrasonic wave, refluxing and distilling with addition of n-butanol and benzene （DRD） and drying by microwave. Characterized with X-ray diffraction （XRD） and transmission electron microscopy （TEM）, BTO spherical particles with tetragonal phase structure are well crystallized, dispersed easily and the average size was less than 10 nm.
基金Project(2004CB619301) supported by the National Basic Research Program of ChinaProject supported by 985-Automotive Engineering of Jilin University, China
文摘The large-scale ZnO rods of submicrometer were prepared on the bare glass using a wet chemical method under different experimental parameters,such as the reactant concentration and the growth time.The microstructure of the ZnO rods was characterized by X-ray diffractometry(XRD) and field emission scanning electron microscopy (FESEM) with the energy dispersive X-ray spectroscopy(EDX),and the optical property was investigated by the room-temperature photoluminescence (PL) spectra.XRD and FESEM results show that the wurtzite structure and rod-like ZnO is obtained.The length (3-8 μm) and the diameter (400 nm-3 μm) vary with the experimental parameters.A strong UV emission at 384 nm and a weak visible yellow-green emission around 570 nm are observed in the PL spectrum.After annealing at 600 ℃ in air,the UV peak intensity increases obviously and the yellow-green peak intensity decreases greatly.The near-band-edge UV emission is attributed to the exciton recombination; the yellow-green emission can be associated with the defect recombination; and some defect complexes may be responsible for the latter emission.
文摘A modified wet chemical route for low-temperature synthesis of the calcium stannate CaSnO3, a potentialmaterial for dielectric applications is reported. Firstly, a precursor CaSn(OH)6 was prepared using tin tetrachloride,calcium chloride and sodium hydroxide at room temperature. Then the precursor was annealed at relatively low tem-perature of 600 ℃ to obtain CaSnO3. The phase identification, thermal behavior and surface morphology of the sam-ples were characterized by element analysis, X-ray diffraction (XRD), thermo-gravimetric (TG) analysis and deriva-tive thermo-gravimetric (DTG) analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron mi-croscopy (SEM) in detail. The results show that CaSnO3 obtained by this method possesses a cubic perovskitestructure with average grain size of 5 μm.
文摘A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate solution with silver nitrate solution at the presence of different modifiers with high-speed stirring at 8-20℃. It is found that the diameters of resulting products are 0.6-6.0 um and the morphologies of the silver microcrystals are greatly affected by the introduced modifiers. It is concluded that the microsized silver crystals with different morphologies can be synthesized by introducing appropriate modifiers at appropriate experimental parameters. Scanning electron microscopy and X-ray diffraction were used to characterize the resulting products.
基金the National Natural Science Foundation of China (Grant No.10702050)the Natural Science Foundation of Tianjin (Grant No.07JCYBJC07500)the Support Plan of Science and Technology of Tianjin (Grant No.07ZCGYSH01700)
文摘A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape factors of the ＂slot＂ and the preset depth used in ＂wetting-drying＂ algorithm. Two typical tests are conducted to examine the performance of the method with the effect of the shape factors of the ＂slot＂ being checked in detail in the first test. Numerical results demonstrate that： 1 ） no additional effort to improve the finite difference scheme is needed to implement ＂slot method＂ in DIVAST, and 2） ＂slot method＂ will simulate wetting and diying processes correctly if the shape factors of the ＂slot＂ being selected properly.
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.
文摘To prepare PZT powder at lower temperature, lead zirconate titanate (PZT) powder (x(Zr)/x(Ti)=56?44) was prepared by wet-dry method. Glycol was used as the solvent, and zirconium oxychloride was used as zirconium source. The properties and structure of the powder were analyzed by XRD, SEM and Sedimentograph. The effects of sintering parameter such as sintering temperature, keeping time and heating-up velocity on structure of PZT power were investigated. The results show that homogeneous PZT with single-phase perovskite structure can be obtained after sintering at 730 ℃ for 2 h, and the average size of PZT powder is about 113 nm.
基金Doctoral Research Start-up Fund of Lanzhou University of Arts and Science(2021-9)Innovation Fund for Colleges and Universities of Gansu Province,China(2022B-265)。
文摘The wetting behavior of liquid tin(Sn)solder on copper(Cu)substrate at 250℃was investigated by the wetting balance method under the action of direct current(DC).The curves of wetting balance were measured and the morphology of the intermetallic compound(IMC)precipitated at the interface were observed.Results show that DC has a significant effect on the wettability and IMC.As the current increases,the balance wetting force and the thickness of the IMC layer increase.The direction of the DC also has a certain effect on the balance wetting force and IMC layer.When the current is negative,the final balance wetting force and the thickness of the Cu_(6)Sn_(5) layer are significantly higher than those in the positive current case,which is attributed to electromigration.The IMC precipitation at the interface provides a chemical driving force for the movement of the triple junction.The interaction of the interface atoms and the chemical reaction are enhanced by DC,thereby improving wettability.Meanwhile,the Marangoni convection caused by DC inside liquid Sn solder changes the structure of triple junction,which provides a physical driving force for the spread of the liquid Sn solder on the Cu substrate.
文摘Soil surface wetness is indispensable land surface parameter in agriculture, hydrology and environmental engineering. This paper explores the relationship between surface radiant temperature and fractional vegetation cover derived from satellite imagery to estimate soil surface wetness (triangle method) in Allahabad district. The pixel distributions create triangular shapes because the range of surface radiant temperature decreases as the amount of vegetation cover increases and sufficient number of pixels exists. A very weak correlation is found between the simulated soil surface wetness and ground measured soil moisture at deeper soil layers (R<sup>2</sup> < 0.15) on all the dates under investigation. This is because the drying rates at the surface discontinue to be linearly correlated to that at lower levels (depths). The standing water pixels distort the shape of the triangle especially at lower left edge of the triangle. This distortion is removable. The spatial and temporal inhomogeneity of soil surface wetness is examined.
基金supported by the National Key Research and Development Program of China(2020YFB1713500)the Chinese 02 Special Fund(2017ZX02408003)+2 种基金the Open Fund of National Joint Engineering Research Center for abrasion control and molding of metal materials(HKDNM201807)the Student Research Training Plan of Henan University of Science and Technology(2020026)the National Undergraduate Innovation and Entrepreneurship Training Program(202010464031,202110464005)。
文摘Rechargeable aqueous Zn-ion batteries(AZIBs)are one of the most promising energy storage devices for large-scale energy storage owing to their high specific capacity,eco-friendliness,low cost and high safety.Nevertheless,zinc metal anodes suffer from severe dendrite growth and side reactions,resulting in the inferior electrochemical performance of AZIBs.To address these problems,surface modification of zinc metal anodes is a facile and effective method to regulate the interaction between the zinc anode and an electrolyte.In this review,the current challenges and strategies for zinc metal anodes are presented.Furthermore,recent advances in surface modification strategies to improve their electrochemical performance are concluded and discussed.Finally,challenges and prospects for future development of zinc metal anodes are proposed.We hope this review will be useful for designing and fabricating highperformance AZIBs and boosting their practical applications.
文摘An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loading of Ga, Al, Ag, and Ce was 0.2 wt.%, 0.002 wt.%, 0.25 wt.%, and 0.15 wt.%, respectively. Intermetallic compounds （IMCs） formed at the interface between Sn-9Zn-0.2Ga-0.002Al-0.25Ag- 0.15Ce solder and Cu substrate were investigated by scanning electron microscope （SEM） and energy dispersive spectroscopy （EDS） analysis. The SEM images illustrate that the IMCs can be divided into two portions from the substrate side to the solder side： a planar CusZns layer and an additional continuous scallop-like AgZn3 layer. The EDS analysis also shows that Ga segregates in the solder abutting upon the interface. X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES） of the surface components of Sn-9Zn-0.2Ga-0.002Al- 0.25Ag-0.15Ce solder indicate that Al aggregates at the surface in the form of Al203 protective fdm, which prevents the further oxidation of the solder surface. On the other hand, Ce aggregates at the subsurface, which may reduce the surface tension of the solder and improve the wettability in consequence.
