In general, atomic emission spectrometry (AES) is an excellent technique for determination of metal elements. However, its capability of determining nonmetals has not been developed well. The major reasons are the res...In general, atomic emission spectrometry (AES) is an excellent technique for determination of metal elements. However, its capability of determining nonmetals has not been developed well. The major reasons are the resonance lines of most nonmetals lie in the vacuum ultraviolet spectral region and the ionic lines of these elements are difficult to be used because the ionization potentials of the elements are very high. And furthermore only He plasma can efficiently excit those ionic resonance lines. The practical application of HeICP-AES to determining the nonmetals is also difficult because its operating and perchace costs are very high. In contrast to HeICPAES, the costs of He microwave induced plasma (MIP)-AES are relatively low, HeMIP has a high excitation capability which can excite ionic lines of various nonmetals and the nonmetals can be determined by HeMIP-AES with a high sensitivity.展开更多
20161720Bai Guoneng(Yunnan Hualian Exploration Company of Mineral Resources,Qujing 655000,China);Zhao Jifen Minerogenetic Law and Minerogenetic Area Division of GemJade in Wenshan Area,Yunnan Province(Yunnan Geology,I...20161720Bai Guoneng(Yunnan Hualian Exploration Company of Mineral Resources,Qujing 655000,China);Zhao Jifen Minerogenetic Law and Minerogenetic Area Division of GemJade in Wenshan Area,Yunnan Province(Yunnan Geology,ISSN1004-1885,CN53-1041/P,34(3),2015,p.352-358,2illus.,1table,6refs.)展开更多
20162490 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,MLR,Beijing,100037,China);Cao Yangtong Chemical Characteristics and Origin of...20162490 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,MLR,Beijing,100037,China);Cao Yangtong Chemical Characteristics and Origin of Saline Springs and Their Significance to Potash Prospecting in the Kuqa Basin,展开更多
The purpose of this research is to develop a SolidWorks? model for transient temperature field of laser welding of PMMA/SS 304 materials for application in fabrication of the ultrasonic back-plate, with a view of opti...The purpose of this research is to develop a SolidWorks? model for transient temperature field of laser welding of PMMA/SS 304 materials for application in fabrication of the ultrasonic back-plate, with a view of optimizing the experimental conditions. The study is carried out on these materials because of the increasing application of both metals and non-metals. The work focuses specifically on these materials because they have been experimentally studied previously and as such, this study can be accepted as an assessment into feasibility of using SolidWorks? model to study the temperature field of the laser welding processes of metals and non-metals. The results of the SolidWorks? transient thermal model show that there is a concentration of high temperatures at the point of contact. It also shows that temperature decreases as we move in (between laser and the top face) to the thickness of the part. Additionally the maximum temperature occurs at the last point of the welding;this may be due to the accumulation of the temperature before arriving at the end. These findings are comparable to the previous simulated and experimental results on temperature field during laser welding of PMMA/SS 304 materials. However, SolidWorks? is shown to present a challenge in modeling a moving source of laser power.展开更多
Platinum group metal(PGM)catalysts have been well recognized as one of the best catalysts towards energy conversion and storage devices,such as fuel cells and water electrolyzers.Nevertheless,their commercial applicat...Platinum group metal(PGM)catalysts have been well recognized as one of the best catalysts towards energy conversion and storage devices,such as fuel cells and water electrolyzers.Nevertheless,their commercial applications are strictly limited by the unsatisfactory catalytic activity and stability.Recently,nonmetallic(H,B,C,N,P,S,etc.)atoms doping is explored to be an efficient strategy to optimize the catalytic activity and durability of PGM-based catalysts via precisely electronic and coordination structure modulation,thus arising tremendous attention.However,systematical discussions on this topic is still lacking.In this review,the representative progresses of nonmetal elements doped PGM-based electrocatalysts for different electrocatalytic reactions are summarized.Firstly,this review discusses the key factors that affect the activity and stability of the catalysts,and introduces the basic principles of nonmetal-doping for improving the performance of PGM-based catalysts.Secondly,advanced characterization techniques and theoretical calculations are highlighted respectively for revealing the activity enhancement mechanism.Then the synthesis methods to incorporate the nonmetals are listed,intending to provide inspirations for the future design of materials.The promising modification strategies for tuning the active species are further proposed.Afterwards,an overview of nonmetal-doped PGM-based catalysts is provided for the electrocatalytic applications,with an emphasis on revealing the structure-performance relationship.Finally,further developments and challenges involving synthesis,mechanism analysis,new materials as well as reactions,stability issues and practical applications are outlined,aiming to promote the in-depth research on advanced PGM-based catalysts.展开更多
BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaf...BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaferrite-paraffin wax composites had been measured by the transmission/reflection coaxial line method in the range from 200 MHz to 6 GHz. The measurement results showed that both the complex dielectric constant and dielectric loss exhibited no significant variation with the measuring frequency increase. It also showed that the real part of permeability decreased as the frequency increasing for all samples, the resonance phenomena due to domain wall resonance was observed in ?' spectra, the calcining temperature strongly affects the microwave properties of BaFe12O19 ferrites, the higher the calcining temperature, the lower the resonance frequency.展开更多
The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat...The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 nm.The purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and diamond.The time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and diamond.The h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr interlayer.The high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr layer.The findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.展开更多
The LiMn2O4 thin film as a cathode material was prepared through solution deposition followed by rapid thermal annealing （RTA）. The phase identification and the study of surface morphology were carried out by X-my d...The LiMn2O4 thin film as a cathode material was prepared through solution deposition followed by rapid thermal annealing （RTA）. The phase identification and the study of surface morphology were carried out by X-my diffraction and scanning electron microscopy. Electrochemical properties were examined by cyclic voltammetry, galvanostatic charge-discharge experiments, and electrochemical impedance spectroscopy. The results show that the film prepared by this method is homogeneous, dense, and crack-free. The thin film has a capacity of 38 μtAh/（cm^2·μm） with the capacity loss of 0.037% per cycle after being cycled for 100 times. The average diffusion coefficient for lithium ions in the RTA-derived LiMn2O4 thin film is 1×10 ^-10 cm^2·s^-1.展开更多
Nanosized SrCe0.95Y0.05O3-δ powders with homogeneous composition were synthesized by the low temperature combustion process based on the Pechini method. A polymeric precursor sol was formed by using citric acid and e...Nanosized SrCe0.95Y0.05O3-δ powders with homogeneous composition were synthesized by the low temperature combustion process based on the Pechini method. A polymeric precursor sol was formed by using citric acid and ethylene glycol as the chelating agents of metal ions. The perovskite-type SrCe0.95Y0.05O3-δpowders with uniform shape and smaller than 25 nm in size were obtained through the combustion of the polymeric precursor sol at the existence of nitric acid and ammonium hydroxide. It was found that modulating the quantifies of nitric acid and ammonium hydroxide could control the particle size, and the quantities of residue carbonate ions were also affected by the quantifies of citric acid and ethylene glycol.展开更多
Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for...Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for 15 min, and relatively pure Ti2O was then obtained. Conductive TiNx was also prepared after altering reaction conditions. Samples were characterized by resistivity, X-ray powder diffraction, transmission electron microscope, Ultraviolet-Visible diffuse reflection, and electromagnetic shielding efficiency. The results indicate that both Ti2O and TiNx have good conductivity. Moreover, Ti2O shows a better solar photocatalytic activity and TiNx does well in the electromagnetic shield.展开更多
Electrochemical nitrate reduction reaction (NITRR) is regarded as a “two birds-one stone” method for the treatment of nitrate contaminant in polluted water and the synthesis of valuable ammonia, which is retarded by...Electrochemical nitrate reduction reaction (NITRR) is regarded as a “two birds-one stone” method for the treatment of nitrate contaminant in polluted water and the synthesis of valuable ammonia, which is retarded by the lack of highly reactive and selective electrocatalysts .Herein, for the first time, nickel foam supported Co_(4) N was designed as a high-performance NITRR catalyst by an in-situ nonmetal leaching-induced strategy.At the optimal potential, the Co_(4) N/NF catalyst achieves ultra-high Faraday efficiency and NH_(3) selectivity of 95.4% and 99.4%, respectively.Ex situ X-ray absorption spectroscopy (XAS), together with other experiments powerfully reveal that the nitrogen vacancies produced by nitrogen leaching are stable and play a key role in boosting nitrate reduction to ammonia.Theoretical calculations confirm that Co_(4) N with abundant nitrogen vacancies can optimize the adsorption energies of NO_(3)^(-) and intermediates, lower the free energy (Δ G ) of the potential-determining step (*NH_(3) to NH_(3) ) and inhibit the formation of N-containing byproducts.In addition, we also conclude that the nitrogen vacancies can stabilize the adsorbed hydrogen, making H_(2) quite difficult to produce, and lowering ΔG from *NO to *NOH, which facilitates the selective reduction of nitrate.This study reveals significant insights about the in-situ nonmetal leaching to enhance the NITRR activity.展开更多
In this paper the authors introduce their past years’study results about the exploitation and application of three sorts of nontraditional nonmetal minerals. In this research, the main aspects and techniques of basic...In this paper the authors introduce their past years’study results about the exploitation and application of three sorts of nontraditional nonmetal minerals. In this research, the main aspects and techniques of basic study for the exploitation and application are summarized, and some key science and technological problems are proposed as the objects of their future research.展开更多
文摘In general, atomic emission spectrometry (AES) is an excellent technique for determination of metal elements. However, its capability of determining nonmetals has not been developed well. The major reasons are the resonance lines of most nonmetals lie in the vacuum ultraviolet spectral region and the ionic lines of these elements are difficult to be used because the ionization potentials of the elements are very high. And furthermore only He plasma can efficiently excit those ionic resonance lines. The practical application of HeICP-AES to determining the nonmetals is also difficult because its operating and perchace costs are very high. In contrast to HeICPAES, the costs of He microwave induced plasma (MIP)-AES are relatively low, HeMIP has a high excitation capability which can excite ionic lines of various nonmetals and the nonmetals can be determined by HeMIP-AES with a high sensitivity.
文摘20161720Bai Guoneng(Yunnan Hualian Exploration Company of Mineral Resources,Qujing 655000,China);Zhao Jifen Minerogenetic Law and Minerogenetic Area Division of GemJade in Wenshan Area,Yunnan Province(Yunnan Geology,ISSN1004-1885,CN53-1041/P,34(3),2015,p.352-358,2illus.,1table,6refs.)
文摘20162490 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,MLR,Beijing,100037,China);Cao Yangtong Chemical Characteristics and Origin of Saline Springs and Their Significance to Potash Prospecting in the Kuqa Basin,
文摘The purpose of this research is to develop a SolidWorks? model for transient temperature field of laser welding of PMMA/SS 304 materials for application in fabrication of the ultrasonic back-plate, with a view of optimizing the experimental conditions. The study is carried out on these materials because of the increasing application of both metals and non-metals. The work focuses specifically on these materials because they have been experimentally studied previously and as such, this study can be accepted as an assessment into feasibility of using SolidWorks? model to study the temperature field of the laser welding processes of metals and non-metals. The results of the SolidWorks? transient thermal model show that there is a concentration of high temperatures at the point of contact. It also shows that temperature decreases as we move in (between laser and the top face) to the thickness of the part. Additionally the maximum temperature occurs at the last point of the welding;this may be due to the accumulation of the temperature before arriving at the end. These findings are comparable to the previous simulated and experimental results on temperature field during laser welding of PMMA/SS 304 materials. However, SolidWorks? is shown to present a challenge in modeling a moving source of laser power.
文摘Platinum group metal(PGM)catalysts have been well recognized as one of the best catalysts towards energy conversion and storage devices,such as fuel cells and water electrolyzers.Nevertheless,their commercial applications are strictly limited by the unsatisfactory catalytic activity and stability.Recently,nonmetallic(H,B,C,N,P,S,etc.)atoms doping is explored to be an efficient strategy to optimize the catalytic activity and durability of PGM-based catalysts via precisely electronic and coordination structure modulation,thus arising tremendous attention.However,systematical discussions on this topic is still lacking.In this review,the representative progresses of nonmetal elements doped PGM-based electrocatalysts for different electrocatalytic reactions are summarized.Firstly,this review discusses the key factors that affect the activity and stability of the catalysts,and introduces the basic principles of nonmetal-doping for improving the performance of PGM-based catalysts.Secondly,advanced characterization techniques and theoretical calculations are highlighted respectively for revealing the activity enhancement mechanism.Then the synthesis methods to incorporate the nonmetals are listed,intending to provide inspirations for the future design of materials.The promising modification strategies for tuning the active species are further proposed.Afterwards,an overview of nonmetal-doped PGM-based catalysts is provided for the electrocatalytic applications,with an emphasis on revealing the structure-performance relationship.Finally,further developments and challenges involving synthesis,mechanism analysis,new materials as well as reactions,stability issues and practical applications are outlined,aiming to promote the in-depth research on advanced PGM-based catalysts.
基金This project is financially supported by the National Natural Science Foundation of China (No.59995320.4)
文摘BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaferrite-paraffin wax composites had been measured by the transmission/reflection coaxial line method in the range from 200 MHz to 6 GHz. The measurement results showed that both the complex dielectric constant and dielectric loss exhibited no significant variation with the measuring frequency increase. It also showed that the real part of permeability decreased as the frequency increasing for all samples, the resonance phenomena due to domain wall resonance was observed in ?' spectra, the calcining temperature strongly affects the microwave properties of BaFe12O19 ferrites, the higher the calcining temperature, the lower the resonance frequency.
基金financially supported by the National Natural Science Foundation of China (Nos. 51871014, 51571015)the National Youth Science Foundation, China (No. 51606193)
文摘The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 nm.The purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and diamond.The time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and diamond.The h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr interlayer.The high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr layer.The findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.
基金This project was financially supported by the Natural Science Foundation of Hunan Province, China (No. 04JJ40038) and the Education Department of Hunan Province, China (No. 04C 475).
文摘The LiMn2O4 thin film as a cathode material was prepared through solution deposition followed by rapid thermal annealing （RTA）. The phase identification and the study of surface morphology were carried out by X-my diffraction and scanning electron microscopy. Electrochemical properties were examined by cyclic voltammetry, galvanostatic charge-discharge experiments, and electrochemical impedance spectroscopy. The results show that the film prepared by this method is homogeneous, dense, and crack-free. The thin film has a capacity of 38 μtAh/（cm^2·μm） with the capacity loss of 0.037% per cycle after being cycled for 100 times. The average diffusion coefficient for lithium ions in the RTA-derived LiMn2O4 thin film is 1×10 ^-10 cm^2·s^-1.
基金This work was financially supported by the National Natural Science Foundation of China (No. 20076025).
文摘Nanosized SrCe0.95Y0.05O3-δ powders with homogeneous composition were synthesized by the low temperature combustion process based on the Pechini method. A polymeric precursor sol was formed by using citric acid and ethylene glycol as the chelating agents of metal ions. The perovskite-type SrCe0.95Y0.05O3-δpowders with uniform shape and smaller than 25 nm in size were obtained through the combustion of the polymeric precursor sol at the existence of nitric acid and ammonium hydroxide. It was found that modulating the quantifies of nitric acid and ammonium hydroxide could control the particle size, and the quantities of residue carbonate ions were also affected by the quantifies of citric acid and ethylene glycol.
基金financially supported by the Science Fund from Tongji University (No. 1380219042)
文摘Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for 15 min, and relatively pure Ti2O was then obtained. Conductive TiNx was also prepared after altering reaction conditions. Samples were characterized by resistivity, X-ray powder diffraction, transmission electron microscope, Ultraviolet-Visible diffuse reflection, and electromagnetic shielding efficiency. The results indicate that both Ti2O and TiNx have good conductivity. Moreover, Ti2O shows a better solar photocatalytic activity and TiNx does well in the electromagnetic shield.
基金financial supports from National Natural Science Foundation of China(Nos.91741105,22006120)Program for Innovation Team Building at Institutions of Higher Education in Chongqing(No.CXTDX201601011)Chongqing Municipal Natural Science Foundation(No.cstc2018jcyjAX0625).
文摘Electrochemical nitrate reduction reaction (NITRR) is regarded as a “two birds-one stone” method for the treatment of nitrate contaminant in polluted water and the synthesis of valuable ammonia, which is retarded by the lack of highly reactive and selective electrocatalysts .Herein, for the first time, nickel foam supported Co_(4) N was designed as a high-performance NITRR catalyst by an in-situ nonmetal leaching-induced strategy.At the optimal potential, the Co_(4) N/NF catalyst achieves ultra-high Faraday efficiency and NH_(3) selectivity of 95.4% and 99.4%, respectively.Ex situ X-ray absorption spectroscopy (XAS), together with other experiments powerfully reveal that the nitrogen vacancies produced by nitrogen leaching are stable and play a key role in boosting nitrate reduction to ammonia.Theoretical calculations confirm that Co_(4) N with abundant nitrogen vacancies can optimize the adsorption energies of NO_(3)^(-) and intermediates, lower the free energy (Δ G ) of the potential-determining step (*NH_(3) to NH_(3) ) and inhibit the formation of N-containing byproducts.In addition, we also conclude that the nitrogen vacancies can stabilize the adsorbed hydrogen, making H_(2) quite difficult to produce, and lowering ΔG from *NO to *NOH, which facilitates the selective reduction of nitrate.This study reveals significant insights about the in-situ nonmetal leaching to enhance the NITRR activity.
文摘In this paper the authors introduce their past years’study results about the exploitation and application of three sorts of nontraditional nonmetal minerals. In this research, the main aspects and techniques of basic study for the exploitation and application are summarized, and some key science and technological problems are proposed as the objects of their future research.
