The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this wo...The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.展开更多
The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing pr...The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering （CO） phase exists in the system, the transition temperature Tco= 275 K, and the system exhibits PM when T 〉 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T 〉 150 K and transforms from paramagnetism to ferromagnetism when T〈 150 K.展开更多
The microstructure and dielectric properties of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3（x=0,0.04,0.08,0.12,0.16） ceramic system were investigated.The Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramics were prepared by the tra...The microstructure and dielectric properties of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3（x=0,0.04,0.08,0.12,0.16） ceramic system were investigated.The Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramics were prepared by the traditional solid-state reaction method and were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and Raman spectrometer.The sintering ability and dielectric properties of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 were found to be improved with the doping of Mn4＋ and W6＋ ions.The densification temperature of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramics decreased from 1 080 ℃ to 1 000 ℃ when x increased from 0 to 0.16.Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramic was found to have the best dielectric properties when x=0.08,larger permittivity（■=547） and smaller dielectric loss（tan■=0.00156）.展开更多
A novel Cu（II）-2,2＇-bipy-supported （bipy = bipyridine） mixed valence decatungstate, [Cu（2,2＇-bipy）2]2Na2W6^VW4^VIO30·2H2O 1, has been synthesized and structurally characterized by X-ray analysis. The crys...A novel Cu（II）-2,2＇-bipy-supported （bipy = bipyridine） mixed valence decatungstate, [Cu（2,2＇-bipy）2]2Na2W6^VW4^VIO30·2H2O 1, has been synthesized and structurally characterized by X-ray analysis. The crystal of 1 is of triclinic, space group P1^- with a= 10.9393（10）, b = 12.0492（2）, c = 12.3783（2）A, a = 80.631（10）, β= 70.226（10）, γ= 72.329（9）^o, V = 1459.64（4）A^3, Z = 1, Dc = 3.582 g/cm^3, F（000） = 1404, R = 0.0553 and wR = 0.1242 for 4607 observed reflections （I 〉 2σ（I））. The EPR spectrum of 1 indicates that its unpaired electrons are placed in the dx2-y2 orbital of the ground state of Cun. Furthermore, compound 1 shows an antiferromagnetic interaction.展开更多
Aniline oligomer composite materials using heteropolyacid H4SiW12O40 as dopant was synthesized, and the effect of the doping concentration on the photoluminescence and surface photovoltaic properties were investigated.
The sample La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was prepared by the solid-state method. Magnetic properties of La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was studied through the measurement of M-T curve, M-H curves and ESR curves o...The sample La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was prepared by the solid-state method. Magnetic properties of La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was studied through the measurement of M-T curve, M-H curves and ESR curves of the sample. The results show that: charge ordering (CO) phase forms at 265 K; the system exhibits paramagnetism when T>265 K; it exhibits long-range anti-ferromagnetism (there is a little FM component in AFM background) and the coexistence of a little FM phase and AFM/CO phase forms when T<225 K; the system transforms from paramagnetism to antiferromagnetism in charge-ordering state with temperature decreasing from 265 to 225 K. The width of ESR spectrum line of the sample La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was measured, and the value of the line width of paramagnetic resonance ΔH_ PP increases with temperature decreasing, which indicates that ferromagnetic connection of the sample strengthens with temperature decreasing.展开更多
The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of it...The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost,triggering the development of various types of extraterrestrial construction materials.A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and optimization.Thirteen types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial environment.Mechanical,thermal and optical,and radiation-shielding properties are considered.The influencing factors and optimization methods for these properties are analyzed.From the perspective of material properties,the existing challenges lie in the comprehensive,long-term,and real characterization of regolith-based construction materials.Correspondingly,the suggested future directions include the application of high-throughput characterization methods,accelerated durability tests,and conducting extraterrestrial experiments.展开更多
The magnetic susceptibility, high field magnetization, and specific heat of spin-5/2 trigonal prismatic ＂Fe6＂ model were investigated in terms of the Heisenberg model by algebraic method. The experimental results sh...The magnetic susceptibility, high field magnetization, and specific heat of spin-5/2 trigonal prismatic ＂Fe6＂ model were investigated in terms of the Heisenberg model by algebraic method. The experimental results showed that the adequate magnetization description of the Heisenberg model were provided. The magnetization curve has tour clear plateaus while the susceptibility exhibits typical anti- ferromagnetic feature. Two board peaks of the specific heat are observed at around 3 K and 15 K, while only a small sharp-peak at low field. Meanwhile, the magnetic susceptibility displays a sharp peak structure at low temperature, which is well consistent with experimental results.展开更多
Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and th...Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues.In this study,the HUST-1 lunar regolith simulant(HLRS)was sintered at 1030,1040,1050,1060,1070,and 1080℃.The effect of sintering temperature on the compressive strength was investigated,and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060℃.Then,the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized.It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080℃.Besides,the heat capacity,thermal conductivity,and coefficient of thermal expansion(CTE)of vacuum sintered HLRS at different temperatures were investigated.Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from-75 to 145℃.Besides,the thermal conductivity of the sintered sample is proportional to density.Finally,the two temperatures of 1040 and 1050℃were selected for a more detailed study of mechanical properties.The results showed that compressive strength of sintered sample is much higher than tensile strength.This study reveals the effects of sintering temperature on the physical,mechanical and thermal properties of vacuum sintered HLRS,and these material parameters will provide support for the construction of future lunar bases.展开更多
In this letter, we investigate the magnetic and ferroelectric properties of polycrystalline MnW1-xMoxO4 （x = 0, 0.05, 0.10, 0.20） compounds. The substitution of nonmagnetic Mo6＋ ions for W6＋ ions modifies the magn...In this letter, we investigate the magnetic and ferroelectric properties of polycrystalline MnW1-xMoxO4 （x = 0, 0.05, 0.10, 0.20） compounds. The substitution of nonmagnetic Mo6＋ ions for W6＋ ions modifies the magnetic transition tem- peratures of MnW1-xMoxO4 by changing the Mn-O-Mn bond. As a result, distinct ferroelectric properties and enhanced magnetoelectric effects are observed in Mo6＋-doped MnWO4 compounds. The effects of substitution of Mo6＋ ions on magnetic properties and magnetoelectric coupling are discussed.展开更多
The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that t...The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.展开更多
Three new one-dimensional compounds [{NaO2（H2O）2}2{（M（H2O）2）2（WO2）2- （BiW9O33）2}]·16H3O＋·XH2O （M = MnII （1）, CoII （2）, NiII （3）） have been synthesized in an aqueous solution, and structura...Three new one-dimensional compounds [{NaO2（H2O）2}2{（M（H2O）2）2（WO2）2- （BiW9O33）2}]·16H3O＋·XH2O （M = MnII （1）, CoII （2）, NiII （3）） have been synthesized in an aqueous solution, and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. These tungstobismuthates reveal that one common feature is the trivacant β-B-BiW9O33 Keggin fragment as the structural building unit. Two β-B-BiW9O33 units are connected by two WO2 groups with further stabilization by the addition of two M（H2O）22＋ groups leading to the M2Bi2W20 anions, which are linked in a 1-D chain by bisodium cluster. Electrochemical analyses show that compounds 1-3 display unique redox properties and good electrocatalytic activity to reduce nitrite.展开更多
文摘The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.
基金This project was financially supported by the National Natural Science Foundation Key Project of China (No. 19934003)the National Key Fundamental Research Project of China (No. 001CB610604)+1 种基金the Natural Science Research Project of the Education Department of Anhui Province (No. 2004KJ331)the Natural Science Research Project of Colleges and Universities of Anhui Province, China (No. 2005KJ234)
文摘The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering （CO） phase exists in the system, the transition temperature Tco= 275 K, and the system exhibits PM when T 〉 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T 〉 150 K and transforms from paramagnetism to ferromagnetism when T〈 150 K.
文摘The microstructure and dielectric properties of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3（x=0,0.04,0.08,0.12,0.16） ceramic system were investigated.The Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramics were prepared by the traditional solid-state reaction method and were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and Raman spectrometer.The sintering ability and dielectric properties of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 were found to be improved with the doping of Mn4＋ and W6＋ ions.The densification temperature of Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramics decreased from 1 080 ℃ to 1 000 ℃ when x increased from 0 to 0.16.Ag（Nb0.8Ta0.2）1-x（Mn0.5W0.5）xO3 ceramic was found to have the best dielectric properties when x=0.08,larger permittivity（■=547） and smaller dielectric loss（tan■=0.00156）.
基金Supported by the NNSFC (90206040)NSF of Fujian Province (2006F3134, 2005J058)
文摘A novel Cu（II）-2,2＇-bipy-supported （bipy = bipyridine） mixed valence decatungstate, [Cu（2,2＇-bipy）2]2Na2W6^VW4^VIO30·2H2O 1, has been synthesized and structurally characterized by X-ray analysis. The crystal of 1 is of triclinic, space group P1^- with a= 10.9393（10）, b = 12.0492（2）, c = 12.3783（2）A, a = 80.631（10）, β= 70.226（10）, γ= 72.329（9）^o, V = 1459.64（4）A^3, Z = 1, Dc = 3.582 g/cm^3, F（000） = 1404, R = 0.0553 and wR = 0.1242 for 4607 observed reflections （I 〉 2σ（I））. The EPR spectrum of 1 indicates that its unpaired electrons are placed in the dx2-y2 orbital of the ground state of Cun. Furthermore, compound 1 shows an antiferromagnetic interaction.
基金We gratefully acknowledge the support of the National Natural Science Foundation of China (29671004).
文摘Aniline oligomer composite materials using heteropolyacid H4SiW12O40 as dopant was synthesized, and the effect of the doping concentration on the photoluminescence and surface photovoltaic properties were investigated.
文摘The sample La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was prepared by the solid-state method. Magnetic properties of La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was studied through the measurement of M-T curve, M-H curves and ESR curves of the sample. The results show that: charge ordering (CO) phase forms at 265 K; the system exhibits paramagnetism when T>265 K; it exhibits long-range anti-ferromagnetism (there is a little FM component in AFM background) and the coexistence of a little FM phase and AFM/CO phase forms when T<225 K; the system transforms from paramagnetism to antiferromagnetism in charge-ordering state with temperature decreasing from 265 to 225 K. The width of ESR spectrum line of the sample La_ 0.3Ca_ 0.7Mn_ 0.96W_ 0.04O_3 was measured, and the value of the line width of paramagnetic resonance ΔH_ PP increases with temperature decreasing, which indicates that ferromagnetic connection of the sample strengthens with temperature decreasing.
基金supported by the National Key Research and Development Program of China(2023YFB3711300 and 2021YFF0500300)the Strategic Research and Consulting Project of the Chinese Academy of Engineering(2023-XZ-90 and 2023-JB-09-10)the National Key Research and Development Program of China(2021YFF0500300).
文摘The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost,triggering the development of various types of extraterrestrial construction materials.A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and optimization.Thirteen types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial environment.Mechanical,thermal and optical,and radiation-shielding properties are considered.The influencing factors and optimization methods for these properties are analyzed.From the perspective of material properties,the existing challenges lie in the comprehensive,long-term,and real characterization of regolith-based construction materials.Correspondingly,the suggested future directions include the application of high-throughput characterization methods,accelerated durability tests,and conducting extraterrestrial experiments.
基金Funded by the National Natural Science Foundation of China(Nos.10774051 and 10804034)the Natural Science Foundation of Guizhou Province of China(No.[2012]2315)
文摘The magnetic susceptibility, high field magnetization, and specific heat of spin-5/2 trigonal prismatic ＂Fe6＂ model were investigated in terms of the Heisenberg model by algebraic method. The experimental results showed that the adequate magnetization description of the Heisenberg model were provided. The magnetization curve has tour clear plateaus while the susceptibility exhibits typical anti- ferromagnetic feature. Two board peaks of the specific heat are observed at around 3 K and 15 K, while only a small sharp-peak at low field. Meanwhile, the magnetic susceptibility displays a sharp peak structure at low temperature, which is well consistent with experimental results.
基金supported by the National Key Research and Development Program of China(Nos.2021YFF0500300 and 2023YFB3711300)the Strategic Research and Consulting Project of the Chinese Academy of Engineering(Nos.2023-XZ-90 and 2023-JB-09-10).
文摘Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues.In this study,the HUST-1 lunar regolith simulant(HLRS)was sintered at 1030,1040,1050,1060,1070,and 1080℃.The effect of sintering temperature on the compressive strength was investigated,and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060℃.Then,the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized.It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080℃.Besides,the heat capacity,thermal conductivity,and coefficient of thermal expansion(CTE)of vacuum sintered HLRS at different temperatures were investigated.Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from-75 to 145℃.Besides,the thermal conductivity of the sintered sample is proportional to density.Finally,the two temperatures of 1040 and 1050℃were selected for a more detailed study of mechanical properties.The results showed that compressive strength of sintered sample is much higher than tensile strength.This study reveals the effects of sintering temperature on the physical,mechanical and thermal properties of vacuum sintered HLRS,and these material parameters will provide support for the construction of future lunar bases.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB932304 and 2009CB929501)the National Natural ScienceFoundation of China(Grant Nos.11174130 and U1232210)
文摘In this letter, we investigate the magnetic and ferroelectric properties of polycrystalline MnW1-xMoxO4 （x = 0, 0.05, 0.10, 0.20） compounds. The substitution of nonmagnetic Mo6＋ ions for W6＋ ions modifies the magnetic transition tem- peratures of MnW1-xMoxO4 by changing the Mn-O-Mn bond. As a result, distinct ferroelectric properties and enhanced magnetoelectric effects are observed in Mo6＋-doped MnWO4 compounds. The effects of substitution of Mo6＋ ions on magnetic properties and magnetoelectric coupling are discussed.
基金Supported by the foundation of laboratory of rare earth chemistry and physics
文摘The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.
基金supported by the National Natural Science Foundation of China (No. 20671026 and 20971032)
文摘Three new one-dimensional compounds [{NaO2（H2O）2}2{（M（H2O）2）2（WO2）2- （BiW9O33）2}]·16H3O＋·XH2O （M = MnII （1）, CoII （2）, NiII （3）） have been synthesized in an aqueous solution, and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. These tungstobismuthates reveal that one common feature is the trivacant β-B-BiW9O33 Keggin fragment as the structural building unit. Two β-B-BiW9O33 units are connected by two WO2 groups with further stabilization by the addition of two M（H2O）22＋ groups leading to the M2Bi2W20 anions, which are linked in a 1-D chain by bisodium cluster. Electrochemical analyses show that compounds 1-3 display unique redox properties and good electrocatalytic activity to reduce nitrite.
