The cyclic voltammetry, open current potential-time curve after potentiostatic electrolysis, the currenttime curve at potential step, XRD, EDAX and EPMA were used to study the electrode process of Ho3+ reduction on n...The cyclic voltammetry, open current potential-time curve after potentiostatic electrolysis, the currenttime curve at potential step, XRD, EDAX and EPMA were used to study the electrode process of Ho3+ reduction on nickel electrode in molten KCI-HoC13 and the phases of surface alloy layer. The Ho-Ni alloys were deposited when Hos+ was reduced on the nickel electrode. The free energies of formation for the intermetallic compounds between Ho and Ni, the diffusion coefficients and diffusion activation energy of Ho astom in the alloy phase were determined.展开更多
The electrical conductivity of NaF-AlF3-CaF2-Al2O3-ZrO2 system was studied by a tube-type cell with fixed cell constant. The results show that the electrical conductivity of NaF-AlF3-3%Al2O3-3%CaF2-ZrO2 molten salt sy...The electrical conductivity of NaF-AlF3-CaF2-Al2O3-ZrO2 system was studied by a tube-type cell with fixed cell constant. The results show that the electrical conductivity of NaF-AlF3-3%Al2O3-3%CaF2-ZrO2 molten salt system decreases with increase of ZrO2 content in an interval of 0-5%. The increase of 1%ZrO2 results in a corresponding electrical conductivity decrease of 0.02 S/cm, and the equivalent conductivity increases with the increase of molar ratio of NaF to AlF3. When the temperature increases by 1 °C, the electrical conductivity increases by 0.004 S/cm. At last, the regression equations of electrical conductivity relative to temperature and ZrO2 are obtained by quadratic regression analysis.展开更多
The single-phase Ba(Mg_(1/3)Nb_(2/3))O_3(BMN) powder was successfully prepared by the KCl molten salt synthesis(MSS) method.The temperature for single-phase BMN powders by MSS was about 400℃ lower than that by the so...The single-phase Ba(Mg_(1/3)Nb_(2/3))O_3(BMN) powder was successfully prepared by the KCl molten salt synthesis(MSS) method.The temperature for single-phase BMN powders by MSS was about 400℃ lower than that by the solid-phase method.The average particle size(APS) was about 0.91μm at 900℃ and increased with increasing synthesis temperature.Based on the APS,the activation energy for particle growth in the MSS,whose value was 64.1kJmol^(-1),was attained.The sinterability of the powder prepared by MSS method was better than that prepared by solid-phase method.展开更多
Implementation of non-precious electrocatalysts is key-enabling for water electrolysis to relieve challenges in energy and environmental sustainability. Self-supporting Ni-V2O3 electrodes consisting of nanostrip-like ...Implementation of non-precious electrocatalysts is key-enabling for water electrolysis to relieve challenges in energy and environmental sustainability. Self-supporting Ni-V2O3 electrodes consisting of nanostrip-like V2O3 perpendicularly anchored on Ni meshes are herein constructed via the electrochemical reduction of soluble NaVO3 in molten salts for enhanced electrocatalytic hydrogen evolution. Such a special configuration in morphology and composition creates a well confined interface between Ni and V2O3. Experimental and Density-Functional-Theory results confirm that the synergy between Ni and V2O3 accelerates the dissociation of H2O for forming hydrogen intermediates and enhances the combination of H*for generating H2.展开更多
The Y-Eu oxalate precursor was prepared with a homogeneous precipitation method. And the additives, Na2CO3, S, NaCl or their combination, were introduced into the precursor to prepare Y2O3 ：Eu^3＋ red phosphors at 10...The Y-Eu oxalate precursor was prepared with a homogeneous precipitation method. And the additives, Na2CO3, S, NaCl or their combination, were introduced into the precursor to prepare Y2O3 ：Eu^3＋ red phosphors at 1000 1300 ℃ for 2 h. The effect of molten salts on particle size and luminescent intensity was studied. The experimental results showed that the complex molten salt （Na：CO3 ＋ S ＋ NaCl） was conductive to enhance the luminescent intensity of Y2O3 ：Eu^3＋. The emission intensity of the phosphor prepared with these additives at 1300 ℃ was about 45% higher than that of the one prepared without molten salt, and about 11% higher than that of the corresponding commercial phosphor. Meanwhile, the particle size of Y2O3 ：Eu^3＋ phosphor was controlled effectively with the molten salt.展开更多
Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method ...Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method in KNO3-NaNO3-NaNO2 melt.The La-Mn-O crystal grows gradually in molten salt with the increase of temperature.It was confirmed that LaMnO3-δ with perovskite structure and incomplete oxygen content were synthesized by molten salt method and presented a three-dimensional shape.LaMnO3-δ stores energy by redox reaction and adsorption of OH-in electrolyte simultaneously.In comparison with the stoichiometric LaMnO3 prepared by the sol-gel method,LaMnO3-δ prepared by molten salt method proffered higher capacitance and better performance.The galvanostatic charge-discharge curve showed specific capacitance of 973.5 F/g under current density of 1 A/g in 6 M KOH.The capacitance of LaMn03-δ was 82.7%under condition of 5 A/g compared with the capacitance at the current of 1A/g,and the specific capacitances of 648.0 and 310.0 F/g were obtained after 2000 and 5000 cycles of galvanostatic charging-discharging,respectively.Molten salt synthesis method is relatively simple and suitable for industrial scale,presenting a promising prospect in the synthesis of perovskite oxide materials.展开更多
A kind of fine and quasi-spherical Y2O3:Eu3+ phosphor was prepared by firing a preparative precursor at 1 200 ℃ for 2 h with the molten salts of Na2CO3, S and NaCl. The precursor was obtained by homogeneous precipita...A kind of fine and quasi-spherical Y2O3:Eu3+ phosphor was prepared by firing a preparative precursor at 1 200 ℃ for 2 h with the molten salts of Na2CO3, S and NaCl. The precursor was obtained by homogeneous precipitation of yttrium and europium with oxalic acid when using EDTA, citric acid or starch as complexant. The structure and morphology of the phosphors were characterized by XRD and SEM, respectively. The influence of complexing environment, firing temperature and molten salts on formation of the phosphor Y2O3:Eu3+ was discussed. The result show that the prepared Y2O3:Eu3+ phosphor is of quasi-spherical structure with size of 2-3 μm. Its luminescent intensity is 30% higher than that of the same phosphor prepared by the same procedure but without molten salts, and is 5% higher than that of commercial Y2O3:Eu3+ red phosphor.展开更多
The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2...The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2)O_(7) was used as a precursor to improve the reduction speed of titanium.Because of the greater number of"diffusion channels"created in cathode as Ca^(2+) liberates from Ca_(3)Ti_(2)O_(7) precursor in the electrodeoxidation process,the O^(2-)diffusion rate was improved significantly by using Ca_(3)Ti_(2)O_(7) instead of CaTiO3 as precursor.Parallel constant voltage electrolysis(3.2 V)confirms that Ca_(3)Ti_(2)O_(7) and CaTiO3 are reduced simultaneously because of their similar crystal structures.However,the reduction area of Ca_(3)Ti_(2)O_(7) spreads much faster than that of CaTiO3,indicating a difference in the O^(2-) diffusion rate.Constant voltage cyclic voltammetry(CV)and theoretical analysis of the crystal structure were also conducted to compare the differences between Ca_(3)Ti_(2)O_(7) and CaTiO3.The results indicate that using a precursor with a greater number of soluble cations,titanium reduction speed can be greatly improved in the electro-deoxidation process.Finally,a new electrolysis method for converting and recycling excess CaO from the Ca_(3)Ti_(2)O_(7) precursor was proposed.展开更多
To improve the separation capacity of uranium in aqueous solutions, 3R-MoS2 nanosheets were prepared with molten salt electro- lysis and further modified with polypyrrole (PPy) to synthesize a hybrid nanoadsorbent (PP...To improve the separation capacity of uranium in aqueous solutions, 3R-MoS2 nanosheets were prepared with molten salt electro- lysis and further modified with polypyrrole (PPy) to synthesize a hybrid nanoadsorbent (PPy/3R-MoS2). The preparation conditions of PPy/3R- MoS2 were investigated and the obtained nanosheets were characterized with scanning electron microscope (SEM), high resolution transmis- sion electron microscope (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectro- scopy (XPS). The results showed that PPy/3R-MoS2 exhibited enhanced adsorption capacity toward U(VI) compared to pure 3R-MoS2 and PPy;the maximum adsorption was 200.4 mg/g. The adsorption mechanism was elucidated with XPS and FTIR: (1) negatively charged PPy/3R-MoS2 nanosheets attracted by an electrostatic interaction;(2) exposed C, N, Mo, and S atoms complexed with U(VI) through co- ordination;(3) Mo in the complex partly reduced the adsorbed U(VI) to U(IV), which further regenerated the adsorption point and continu- ously adsorbed U(VI). The design of the PPy/3R-MoS2 composite with a high adsorption capacity and chemical stability provides a new direc- tion for the removal of radionuclide.展开更多
Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti...Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti （OC4H9）4） as raw materials. The synthesis temperature of Bi4Ti3O12 platelets was decreased to 650℃ from 900-1100℃. The phase compositions and crystalline morphology of Bi4Ti3O12 platelets were investigated by XRD and SEM. The experimental results indicate that Bi4Ti3O12 platelets containing tetragonal and orthorhombic phase with the size of 1-3μm can be synthesized at 650℃ for 2 h, and the orthorhombic phase becomes the dominant phase at 750℃ for 5 h. The size and proportion of Bi4Ti3O12 platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases to about ninety percent, and the platelets grow up to about 3-10μm at 750℃ for 5 h from 1-2μm at 650℃ for 2 h. This technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods.展开更多
The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was inv...The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was investigated by measuring the mass loss of a rotating sintered corundum disc. And the following empirical equation was derived when superheat degree was no more than 60 °C： w（Al2O3）sat=A×（T/1000）B, where A= –1.85774＋ 26.754234w（AlF3）–0.3683–0.00783KR2.363＋0.010266KR2.3048＋0.7902w（AlF3）0.00652, B=112.4625–53.2567w（AlF3）0.4236＋ 5.1079w（AlF3）0.9241＋0.01542w（AlF3）1.3540. Considering both higher alumina solubility and not too high superheat de gree are required, alumina solubility of different compositions at not the same temperature but the same superheat degree was studied, which will be more industrial helpful for selecting prospective compositions. The results show that the composition deserved to be further tested in lower temperature cells is 10%―30% KR and 23%―26%（mass fraction） AlF3.展开更多
The physicochemical properties of the system, such as density, surface tension, specific conductance and melting point were measured. The results were discussed.
基金the National Natural Science Foundation of China!2890179
文摘The cyclic voltammetry, open current potential-time curve after potentiostatic electrolysis, the currenttime curve at potential step, XRD, EDAX and EPMA were used to study the electrode process of Ho3+ reduction on nickel electrode in molten KCI-HoC13 and the phases of surface alloy layer. The Ho-Ni alloys were deposited when Hos+ was reduced on the nickel electrode. The free energies of formation for the intermetallic compounds between Ho and Ni, the diffusion coefficients and diffusion activation energy of Ho astom in the alloy phase were determined.
基金Project (2007CB210305) supported by the National Basic Research Program of ChinaProject (51074045) supported by the National Natural Science Foundation of China
文摘The electrical conductivity of NaF-AlF3-CaF2-Al2O3-ZrO2 system was studied by a tube-type cell with fixed cell constant. The results show that the electrical conductivity of NaF-AlF3-3%Al2O3-3%CaF2-ZrO2 molten salt system decreases with increase of ZrO2 content in an interval of 0-5%. The increase of 1%ZrO2 results in a corresponding electrical conductivity decrease of 0.02 S/cm, and the equivalent conductivity increases with the increase of molar ratio of NaF to AlF3. When the temperature increases by 1 °C, the electrical conductivity increases by 0.004 S/cm. At last, the regression equations of electrical conductivity relative to temperature and ZrO2 are obtained by quadratic regression analysis.
基金FinanciallysupportedbytheMinistryofEducationofChi na .
文摘The single-phase Ba(Mg_(1/3)Nb_(2/3))O_3(BMN) powder was successfully prepared by the KCl molten salt synthesis(MSS) method.The temperature for single-phase BMN powders by MSS was about 400℃ lower than that by the solid-phase method.The average particle size(APS) was about 0.91μm at 900℃ and increased with increasing synthesis temperature.Based on the APS,the activation energy for particle growth in the MSS,whose value was 64.1kJmol^(-1),was attained.The sinterability of the powder prepared by MSS method was better than that prepared by solid-phase method.
基金the funding support from the National Natural Science Foundation of China(51722404,51674177,51804221 and 91845113)the National Key R&D Program of China(2018YFE0201703)+2 种基金the China Postdoctoral Science Foundation(2018M642906 and 2019T120684)the Fundamental Research Funds for the Central Universities(2042017kf0200)the Hubei Provincial Natural Science Foundation of China(2019CFA065)。
文摘Implementation of non-precious electrocatalysts is key-enabling for water electrolysis to relieve challenges in energy and environmental sustainability. Self-supporting Ni-V2O3 electrodes consisting of nanostrip-like V2O3 perpendicularly anchored on Ni meshes are herein constructed via the electrochemical reduction of soluble NaVO3 in molten salts for enhanced electrocatalytic hydrogen evolution. Such a special configuration in morphology and composition creates a well confined interface between Ni and V2O3. Experimental and Density-Functional-Theory results confirm that the synergy between Ni and V2O3 accelerates the dissociation of H2O for forming hydrogen intermediates and enhances the combination of H*for generating H2.
基金Project supported by the National Natural Science Foundation of China (50372086)the Ministry of Science and Technology of Chi-na (2006CB601104)
文摘The Y-Eu oxalate precursor was prepared with a homogeneous precipitation method. And the additives, Na2CO3, S, NaCl or their combination, were introduced into the precursor to prepare Y2O3 ：Eu^3＋ red phosphors at 1000 1300 ℃ for 2 h. The effect of molten salts on particle size and luminescent intensity was studied. The experimental results showed that the complex molten salt （Na：CO3 ＋ S ＋ NaCl） was conductive to enhance the luminescent intensity of Y2O3 ：Eu^3＋. The emission intensity of the phosphor prepared with these additives at 1300 ℃ was about 45% higher than that of the one prepared without molten salt, and about 11% higher than that of the corresponding commercial phosphor. Meanwhile, the particle size of Y2O3 ：Eu^3＋ phosphor was controlled effectively with the molten salt.
基金financially supported by the China Scholarship Council,the National Natural Science Foundation of China(21976047,21790373 and 51774104)the Fundamental Research funds for the Central Universities(3072019CF1005)+1 种基金the Scientific Research and Special Foundation Heilongjiang Postdoctoral Science Foundation(LBH-Q15019,LBH-Q15020 and LBH-TZ0411)Ph.D.Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(3072019GIP1011)。
文摘Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method in KNO3-NaNO3-NaNO2 melt.The La-Mn-O crystal grows gradually in molten salt with the increase of temperature.It was confirmed that LaMnO3-δ with perovskite structure and incomplete oxygen content were synthesized by molten salt method and presented a three-dimensional shape.LaMnO3-δ stores energy by redox reaction and adsorption of OH-in electrolyte simultaneously.In comparison with the stoichiometric LaMnO3 prepared by the sol-gel method,LaMnO3-δ prepared by molten salt method proffered higher capacitance and better performance.The galvanostatic charge-discharge curve showed specific capacitance of 973.5 F/g under current density of 1 A/g in 6 M KOH.The capacitance of LaMn03-δ was 82.7%under condition of 5 A/g compared with the capacitance at the current of 1A/g,and the specific capacitances of 648.0 and 310.0 F/g were obtained after 2000 and 5000 cycles of galvanostatic charging-discharging,respectively.Molten salt synthesis method is relatively simple and suitable for industrial scale,presenting a promising prospect in the synthesis of perovskite oxide materials.
基金Project(50372086) supported by the National Natural Science Foundation of China
文摘A kind of fine and quasi-spherical Y2O3:Eu3+ phosphor was prepared by firing a preparative precursor at 1 200 ℃ for 2 h with the molten salts of Na2CO3, S and NaCl. The precursor was obtained by homogeneous precipitation of yttrium and europium with oxalic acid when using EDTA, citric acid or starch as complexant. The structure and morphology of the phosphors were characterized by XRD and SEM, respectively. The influence of complexing environment, firing temperature and molten salts on formation of the phosphor Y2O3:Eu3+ was discussed. The result show that the prepared Y2O3:Eu3+ phosphor is of quasi-spherical structure with size of 2-3 μm. Its luminescent intensity is 30% higher than that of the same phosphor prepared by the same procedure but without molten salts, and is 5% higher than that of commercial Y2O3:Eu3+ red phosphor.
基金the National Natural Science Foundation of China(Nos.51604255 and U1702251)。
文摘The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2)O_(7) was used as a precursor to improve the reduction speed of titanium.Because of the greater number of"diffusion channels"created in cathode as Ca^(2+) liberates from Ca_(3)Ti_(2)O_(7) precursor in the electrodeoxidation process,the O^(2-)diffusion rate was improved significantly by using Ca_(3)Ti_(2)O_(7) instead of CaTiO3 as precursor.Parallel constant voltage electrolysis(3.2 V)confirms that Ca_(3)Ti_(2)O_(7) and CaTiO3 are reduced simultaneously because of their similar crystal structures.However,the reduction area of Ca_(3)Ti_(2)O_(7) spreads much faster than that of CaTiO3,indicating a difference in the O^(2-) diffusion rate.Constant voltage cyclic voltammetry(CV)and theoretical analysis of the crystal structure were also conducted to compare the differences between Ca_(3)Ti_(2)O_(7) and CaTiO3.The results indicate that using a precursor with a greater number of soluble cations,titanium reduction speed can be greatly improved in the electro-deoxidation process.Finally,a new electrolysis method for converting and recycling excess CaO from the Ca_(3)Ti_(2)O_(7) precursor was proposed.
基金the National Nat-ural Science Foundation of China(Nos.21906019,21906018,21561002,21866004,and 21866003)the Sci-ence&Technology Support Program of Jiangxi Province,China(No.2018ACB21007)+1 种基金the Jiangxi Program of Aca-demic and Technical Leaders of Major Disciplines,China(No.20182BCB22011)the Project of the Jiangxi Provincial Department of Education,China(Nos.GJJ160550,GJJ180385,and GJJ180400).
文摘To improve the separation capacity of uranium in aqueous solutions, 3R-MoS2 nanosheets were prepared with molten salt electro- lysis and further modified with polypyrrole (PPy) to synthesize a hybrid nanoadsorbent (PPy/3R-MoS2). The preparation conditions of PPy/3R- MoS2 were investigated and the obtained nanosheets were characterized with scanning electron microscope (SEM), high resolution transmis- sion electron microscope (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectro- scopy (XPS). The results showed that PPy/3R-MoS2 exhibited enhanced adsorption capacity toward U(VI) compared to pure 3R-MoS2 and PPy;the maximum adsorption was 200.4 mg/g. The adsorption mechanism was elucidated with XPS and FTIR: (1) negatively charged PPy/3R-MoS2 nanosheets attracted by an electrostatic interaction;(2) exposed C, N, Mo, and S atoms complexed with U(VI) through co- ordination;(3) Mo in the complex partly reduced the adsorbed U(VI) to U(IV), which further regenerated the adsorption point and continu- ously adsorbed U(VI). The design of the PPy/3R-MoS2 composite with a high adsorption capacity and chemical stability provides a new direc- tion for the removal of radionuclide.
文摘Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti （OC4H9）4） as raw materials. The synthesis temperature of Bi4Ti3O12 platelets was decreased to 650℃ from 900-1100℃. The phase compositions and crystalline morphology of Bi4Ti3O12 platelets were investigated by XRD and SEM. The experimental results indicate that Bi4Ti3O12 platelets containing tetragonal and orthorhombic phase with the size of 1-3μm can be synthesized at 650℃ for 2 h, and the orthorhombic phase becomes the dominant phase at 750℃ for 5 h. The size and proportion of Bi4Ti3O12 platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases to about ninety percent, and the platelets grow up to about 3-10μm at 750℃ for 5 h from 1-2μm at 650℃ for 2 h. This technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods.
基金Supported by the National Basic Research Program of China(No.2005CB623703)the National High-Tech Research and Development Program of China(No.2008AA030503)
文摘The alumina solubility in the title system within the composition range of KR{m（K3AlF6）/[m（K3AlF6）＋ m（Na3AlF6）]} 10%―50%, a ternary Na3AlF6-K3AlF6-AlF3 molten system with 23%―29%（mass fraction） AlF3 was investigated by measuring the mass loss of a rotating sintered corundum disc. And the following empirical equation was derived when superheat degree was no more than 60 °C： w（Al2O3）sat=A×（T/1000）B, where A= –1.85774＋ 26.754234w（AlF3）–0.3683–0.00783KR2.363＋0.010266KR2.3048＋0.7902w（AlF3）0.00652, B=112.4625–53.2567w（AlF3）0.4236＋ 5.1079w（AlF3）0.9241＋0.01542w（AlF3）1.3540. Considering both higher alumina solubility and not too high superheat de gree are required, alumina solubility of different compositions at not the same temperature but the same superheat degree was studied, which will be more industrial helpful for selecting prospective compositions. The results show that the composition deserved to be further tested in lower temperature cells is 10%―30% KR and 23%―26%（mass fraction） AlF3.
文摘The physicochemical properties of the system, such as density, surface tension, specific conductance and melting point were measured. The results were discussed.
