Elucidation of a reaction mechanism is the most critical aspect for designing electrodes for highperformance secondary batteries.Herein,we investigate the sodium insertion/extraction into an iron fluoride hydrate(FeF_...Elucidation of a reaction mechanism is the most critical aspect for designing electrodes for highperformance secondary batteries.Herein,we investigate the sodium insertion/extraction into an iron fluoride hydrate(FeF_(3)·0.5H_(2)O)electrode for sodium-ion batteries(SIBs).The electrode material is prepared by employing an ionic liquid 1-butyl-3-methylimidazolium-tetrafluoroborate,which serves as a reaction medium and precursor for F^(-)ions.The crystal structure of FeF_(3)·0.5H_(2)O is observed as pyrochlore type with large open 3-D tunnels and a unit cell volume of 1129A^(3).The morphology of FeF_(3)·0.5H_(2)O is spherical shape with a mesoporous structure.The microstructure analysis reveals primary particle size of around 10 nm.The FeF_(3)·0.5H_(2)O cathode exhibits stable discharge capacities of 158,210,and 284 mA h g^(-1) in three different potential ranges of 1.5-4.5,1.2-4.5,and 1.0-4.5 V,respectively at 0.05 C rate.The specific capacities remained stable in over 50 cycles in all three potential ranges,while the rate capability was best in the potential range of 1.5-4.5 V.The electrochemical sodium storage mechanism is studied using X-ray absorption spectroscopy,indicating higher conversion at a more discharged state.Ex-situ M?ssbauer spectroscopy strengthens the results for reversible reduction/oxidation of Fe.These results will be favorable to establish high-performance cathode materials with selective voltage window for SIBs.展开更多
MgxNi1-xFe_(2)O_(4)(x=0,0.25,0.5,0.75,1)spinel ferrite material was analyzed to determine its magnetic properties and structure.X-ray diffraction(XRD),Mössbauer spectroscopy,and vibrating sample magnetometer(VSM)...MgxNi1-xFe_(2)O_(4)(x=0,0.25,0.5,0.75,1)spinel ferrite material was analyzed to determine its magnetic properties and structure.X-ray diffraction(XRD),Mössbauer spectroscopy,and vibrating sample magnetometer(VSM)characterization were performed on the samples prepared using the sol-gel method.The results from XRD confirmed the existence of the single-phase cubic spinel structures Fd3m,as well as the evolution of the crystalline size(D),the lattice parameter(a)and cell volume in compounds.The Mössbauer spectra showed the distribution of cations and changes in the magnetic properties of the sample.VSM measurement revealed that the samples were room-temperature ferromagnetic.Moreover,the saturation magnetization(Ms)of the samples changed with the Mg^(2+)ion content x,and a maximum occured at x=0.5.Doping with Mg^(2+)ions increased the transfer of Ni^(2+)ions to tetrahedral sites,thus increasing the magnetic moment difference between tetrahedral(A)and octahedral(B)sites.Specifically,doping NiFe_(2)O_(4) with Mg^(2+)ions can enhance its magnetic properties and enhance its saturation magnetization.展开更多
In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition met...In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition metal oxides (TM;in this case Fe<sub>2</sub>O<sub>3</sub>) or rare-earth oxides<sub>3</sub>, and investigated the location of the alien metal (Fe in this case) in the structure. Previous AC magnetic susceptibility measurements at low temperatures have been consistent with the formation of arrays of TM magnetic moments along the widely spaced columns parallel to the crystallographic b-axis in the Nb<sub>28</sub>O<sub>70</sub> structure. To obtain further details about the TM distribution, the previous investigation has been extended now to include a room-temperature Mössbauer spectroscopic analysis of the Fe-doped material. The data are consistent with the presence of low-spin Fe<sup>3+</sup> ions in both octahedral and tetrahedral coordinations of oxygens, and confirm (as suggested in the previous work) that Fe also interchanges positions with Nb ions located at tetrahedrally coordinated sites in the columns of the structure.展开更多
In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition met...In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition metal oxides (TM;in this case Fe<sub>2</sub>O<sub>3</sub>) or rare-earth oxides<sub>3</sub>, and investigated the location of the alien metal (Fe in this case) in the structure. Previous AC magnetic susceptibility measurements at low temperatures have been consistent with the formation of arrays of TM magnetic moments along the widely spaced columns parallel to the crystallographic b-axis in the Nb<sub>28</sub>O<sub>70</sub> structure. To obtain further details about the TM distribution, the previous investigation has been extended now to include a room-temperature Mössbauer spectroscopic analysis of the Fe-doped material. The data are consistent with the presence of low-spin Fe<sup>3+</sup> ions in both octahedral and tetrahedral coordinations of oxygens, and confirm (as suggested in the previous work) that Fe also interchanges positions with Nb ions located at tetrahedrally coordinated sites in the columns of the structure.展开更多
The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, a...The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe^(2+)/Fe^(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe^(3+), and para-Fe^(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.展开更多
The emission Mssbauer Spectroscopy in cotnbination with transmission electron microscope was used to study NiTi shape memory alloy. The damage and the precipitated phase in NiTi alloy have heen discussed.
The structure of Fe-M ultrafine particle catalysts was investigated by in situ Mossbauer spectroscopy. Emphasis has particularly been put on the effect of the second metal component. It was found that the incorporatio...The structure of Fe-M ultrafine particle catalysts was investigated by in situ Mossbauer spectroscopy. Emphasis has particularly been put on the effect of the second metal component. It was found that the incorporation of second metal component hinders the reduction and carburization of iron- containing phase in the presence of H2 and CO, and the degree of hindrance is in the order of Mg】Mn】Zn due to the interaction between iron and the second metal component. Consequently, the formation of light olefinic products is in the order of Fe- Mg】 Fe- Mn】 Fe- Zn catalysts consistent with the F-T synthesis performance.展开更多
采用机械合金化法制备Al V Fe纳米粉末 ,通过测定M ssbauer效应 ,研究了不同球磨能量对制备Al V Fe纳米粉末的影响·结果表明 ,振动球磨与高能球磨所制备的Al V Fe纳米粉末结构均由非晶和α Al纳米晶组成 ,其非晶含量随着球磨能量...采用机械合金化法制备Al V Fe纳米粉末 ,通过测定M ssbauer效应 ,研究了不同球磨能量对制备Al V Fe纳米粉末的影响·结果表明 ,振动球磨与高能球磨所制备的Al V Fe纳米粉末结构均由非晶和α Al纳米晶组成 ,其非晶含量随着球磨能量的增加而有所不同·展开更多
基金supported by the Basic Science Research Program of the National Research Foundation(NRF)of South Koreafunded by the Ministry of Science&ICT and Future Planning(NRF-2020M3H4A3081889)KIST Institutional Program of South Korea(Project Nos.2E31860)。
文摘Elucidation of a reaction mechanism is the most critical aspect for designing electrodes for highperformance secondary batteries.Herein,we investigate the sodium insertion/extraction into an iron fluoride hydrate(FeF_(3)·0.5H_(2)O)electrode for sodium-ion batteries(SIBs).The electrode material is prepared by employing an ionic liquid 1-butyl-3-methylimidazolium-tetrafluoroborate,which serves as a reaction medium and precursor for F^(-)ions.The crystal structure of FeF_(3)·0.5H_(2)O is observed as pyrochlore type with large open 3-D tunnels and a unit cell volume of 1129A^(3).The morphology of FeF_(3)·0.5H_(2)O is spherical shape with a mesoporous structure.The microstructure analysis reveals primary particle size of around 10 nm.The FeF_(3)·0.5H_(2)O cathode exhibits stable discharge capacities of 158,210,and 284 mA h g^(-1) in three different potential ranges of 1.5-4.5,1.2-4.5,and 1.0-4.5 V,respectively at 0.05 C rate.The specific capacities remained stable in over 50 cycles in all three potential ranges,while the rate capability was best in the potential range of 1.5-4.5 V.The electrochemical sodium storage mechanism is studied using X-ray absorption spectroscopy,indicating higher conversion at a more discharged state.Ex-situ M?ssbauer spectroscopy strengthens the results for reversible reduction/oxidation of Fe.These results will be favorable to establish high-performance cathode materials with selective voltage window for SIBs.
基金Project supported by the National Natural Science Foundation of China (Grant No.11447231)the National Undergraduate Innovation and Entrepreneurship Training Program Support Projects of China+2 种基金the Natural Science Foundation of Hunan Province,China (Grant No.2020JJ4517)the Research Foundation of the Education Bureau of Hunan Province,China (Grant Nos.19A434,19A433,and 19C1621)the Opening Project of the Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China (Grant Nos.2019KFY10 and 2019KFY09)。
文摘MgxNi1-xFe_(2)O_(4)(x=0,0.25,0.5,0.75,1)spinel ferrite material was analyzed to determine its magnetic properties and structure.X-ray diffraction(XRD),Mössbauer spectroscopy,and vibrating sample magnetometer(VSM)characterization were performed on the samples prepared using the sol-gel method.The results from XRD confirmed the existence of the single-phase cubic spinel structures Fd3m,as well as the evolution of the crystalline size(D),the lattice parameter(a)and cell volume in compounds.The Mössbauer spectra showed the distribution of cations and changes in the magnetic properties of the sample.VSM measurement revealed that the samples were room-temperature ferromagnetic.Moreover,the saturation magnetization(Ms)of the samples changed with the Mg^(2+)ion content x,and a maximum occured at x=0.5.Doping with Mg^(2+)ions increased the transfer of Ni^(2+)ions to tetrahedral sites,thus increasing the magnetic moment difference between tetrahedral(A)and octahedral(B)sites.Specifically,doping NiFe_(2)O_(4) with Mg^(2+)ions can enhance its magnetic properties and enhance its saturation magnetization.
文摘In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition metal oxides (TM;in this case Fe<sub>2</sub>O<sub>3</sub>) or rare-earth oxides<sub>3</sub>, and investigated the location of the alien metal (Fe in this case) in the structure. Previous AC magnetic susceptibility measurements at low temperatures have been consistent with the formation of arrays of TM magnetic moments along the widely spaced columns parallel to the crystallographic b-axis in the Nb<sub>28</sub>O<sub>70</sub> structure. To obtain further details about the TM distribution, the previous investigation has been extended now to include a room-temperature Mössbauer spectroscopic analysis of the Fe-doped material. The data are consistent with the presence of low-spin Fe<sup>3+</sup> ions in both octahedral and tetrahedral coordinations of oxygens, and confirm (as suggested in the previous work) that Fe also interchanges positions with Nb ions located at tetrahedrally coordinated sites in the columns of the structure.
文摘In search of an experimental route to produce linear arrays of spins without the use of nanotechnological tools, we have doped Nb<sub>28</sub>O<sub>70</sub> with small amounts of transition metal oxides (TM;in this case Fe<sub>2</sub>O<sub>3</sub>) or rare-earth oxides<sub>3</sub>, and investigated the location of the alien metal (Fe in this case) in the structure. Previous AC magnetic susceptibility measurements at low temperatures have been consistent with the formation of arrays of TM magnetic moments along the widely spaced columns parallel to the crystallographic b-axis in the Nb<sub>28</sub>O<sub>70</sub> structure. To obtain further details about the TM distribution, the previous investigation has been extended now to include a room-temperature Mössbauer spectroscopic analysis of the Fe-doped material. The data are consistent with the presence of low-spin Fe<sup>3+</sup> ions in both octahedral and tetrahedral coordinations of oxygens, and confirm (as suggested in the previous work) that Fe also interchanges positions with Nb ions located at tetrahedrally coordinated sites in the columns of the structure.
基金supported by the Natural Science Foundation of China(NSFC No.41376080)the 12th Five-Year Plan project of the State Key Laboratory of Ore-deposit Geochemistry,Chinese Academy of Sciences(SKLODG-ZY125-08)
文摘The Dounan manganese deposit is a typical large-scale marine sedimentary manganese deposit of the Middle Triassic in China. The metallogenic environment and change process directly dictate the migration, enrichment, and precipitation of Mn. To better understand its metallogenetic environment, a detailed study was undertaken involving field observation, mineralogical and geochemical and M?ssbauer spectroscopic analyses. The major findings are as follows:(1) Lithofacies paleogeography, sedimentary structural characteristics, and geochemical indexes indicate that the deposits were formed in an epicontinental marine sedimentary basin environment of normal salinity;(2) there were three ore phases including Mn oxides, Mn carbonates, and mixed Mn ores. The ore minerals found were braunite, manganite, Ca-rhodochrosite, manganocalcite, and kutnahorite. Petrographic and mineralogical information indicates that the metallogenic environment was a weakly alkaline and weakly oxidized to weakly reduced environment, and the mineralization occurred near the redox interface;(3) the V/(V + Ni)ratios, δCe and Fe^(2+)/Fe^(3+) found in profiles of Baigu and Gake ore sections show that the redox conditions of the ore-forming environment were continuously changing; and(4) three Fe species, α-Fe_2O_3, para-Fe^(3+), and para-Fe^(2+),were found in hematite and clay mineral samples using M?ssbauer spectrum analysis. The presence and distribution of these Fe species indicate that the deposit was formed in a typical sedimentary environment during the mineralization process. In summary, our study showed that redox was a key factor controlling the mineralization of the Dounan manganese deposit. Our results have led us to the conclusion that transgression and regression caused fluctuations in sea level, which in turn caused the change of the redox environment. M?ssbauer spectroscopy is an effective tool for studying the redox conditions of the paleoenvironment in which sedimentary manganese deposits were formed.
文摘The emission Mssbauer Spectroscopy in cotnbination with transmission electron microscope was used to study NiTi shape memory alloy. The damage and the precipitated phase in NiTi alloy have heen discussed.
基金The Project Supported by National Natural Science Foundation of China
文摘The structure of Fe-M ultrafine particle catalysts was investigated by in situ Mossbauer spectroscopy. Emphasis has particularly been put on the effect of the second metal component. It was found that the incorporation of second metal component hinders the reduction and carburization of iron- containing phase in the presence of H2 and CO, and the degree of hindrance is in the order of Mg】Mn】Zn due to the interaction between iron and the second metal component. Consequently, the formation of light olefinic products is in the order of Fe- Mg】 Fe- Mn】 Fe- Zn catalysts consistent with the F-T synthesis performance.
