A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out i...A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.展开更多
With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been...With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.展开更多
Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues...Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.展开更多
Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products we...Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.展开更多
The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors f...The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...展开更多
Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolec...Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections.Sulfonyl fluorides,one of the most important sulfur(Ⅵ)fluoride species,have attracted enormous attention in diverse fields,ranging from organic synthesis and material science,to chemical biology and drug discovery.This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides,which include aromatic,aliphatic,alkenyl,and alkynyl sulfonyl fluorides.While not meant to be exhaustive,the purpose is to give a timely overview and insight in this field,and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.展开更多
Praseodymium（III） doped CeF3, CeF3：Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur- factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subj...Praseodymium（III） doped CeF3, CeF3：Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur- factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subjected to a hydrothermal treatment, which led to the formation of crystalline nanoluminophores, composed of spherical （30 nm） and elongated （40-200 nm） nanos- tructures. Due to the presence of Pr3＋ ions, the synthesized nanomaterials showed yellow luminescence under a blue light irradiation. The nanoluminophore based on the YF3 host revealed the most promising spectroscopic properties, i.e., bright and intensive emission, hence it was investigated in detail. The photophysical properties of the nanomaterials obtained were studied by powder X-ray diffrac- tion （XRD）, transmission electron microscopy （TEM） and spectrofluorometry, i.e., measurements of excitation/emission spectra and luminescence decay curves.展开更多
Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TE...Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TEM) was used to characterize the nanoparticles. The nanoparticles were modified by PEI, CTAB, PAA and Ci, respectively. It was feasible for function by -COOH and -NH2 groups, due to the surface modification. Moreover, different surface modifications of the nanoparticles were examined. The possible formation mechanisms for fluoride nanoparticles with surface modification were presented in detail. More importantly, it is expected to be widely applied to biomedicine.展开更多
Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide ran...Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.展开更多
A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to suc...A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to success is the use of pyridine-oxazoline as ligand and(MeO)_(2)MeSiH as the hydrogen source.This transformation demonstrates high efficiency,mild conditions,good functional-group compatibility and great potential in the drug discovery.展开更多
The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic volta...The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic voltammetry. The electrodeposited products were analysed by X ray diffraction. The results show that the electrolytic codeposition of Y Al alloy in the LiF YF 3 Y 2O 3 Al 2O 3 system without AlF 3 can be achieved at the same potential for Y(Ⅲ) and Al(Ⅲ) which have great difference in deposition potential. It is beneficial to codeposition of Y(Ⅲ) and Al(Ⅲ) when temperature rises. The potential of beginning codeposition is about -0.85 V ( vs Pt reference electrode), but only at the potential of -0.95 V or more negative can Y based Al alloy containing a great amount of yttrium be obtained.展开更多
The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H Vincent and D. Mark at the Institute of Occupational Me...The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H Vincent and D. Mark at the Institute of Occupational Medicine（IOM）, personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648 a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-Ntrimethylammonium bromide（CTAB） were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8 μg/L and 24 μg/L, respectively The linear range of calibration was 0.01–10 mg/L, which corresponds to 0.0001–0.1 mg of fluorides per m3 in collection of a 20 L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20–1.82 mg/m3, while the inhalable fraction contained 0.23–1.96 mg/m3 of fluorides during an eight-hour working day in the welding room.展开更多
The thermodynamic and dynamic behaviour of Ni^(2+)|Ni couple in FLINAK melt is investigated by us- ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and a large exchange cur...The thermodynamic and dynamic behaviour of Ni^(2+)|Ni couple in FLINAK melt is investigated by us- ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and a large exchange current density(6 mA·cm^(-2)).A single crystal LaF_3 which is a fluoride ion conductor used as a membrane of the Ni^(2+)|Ni couple reference electrode is reliable in FLINAK melts at 973 K.The poten- tial of LaF_3 membrane reference electrode is constant within±2 mV.The boron nitride used as a salt bridge was not good in FLINAK melts.The platinum electrode is studied by using micropolarization.The equilibrium potential of Pt electrode is dependent on the absorption and the electrochemical reaction.The potential is stable for a constant composition at constant temperature.展开更多
The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp...The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp line and its valence-state is stable.展开更多
This article focuses on the electrorefining process in molten fluorides to selectively recover zirconium from one Zr-based metallic alloy involved in the field of nuclear energy: Zircaloy-4. Firstly, zirconium electro...This article focuses on the electrorefining process in molten fluorides to selectively recover zirconium from one Zr-based metallic alloy involved in the field of nuclear energy: Zircaloy-4. Firstly, zirconium electrodeposition was investigated in molten LiF-NaF at 750˚C in order to determine appropriate operating conditions to ensure Zr metal recovery: concentration and applied current density. Then, anodic behaviour of Zircaloy-4 was studied and compared to its composing elements. These results allowed us to define an adapted electrorefining strategy. Electrorefining progress, anodic and cathodic faradic efficiencies were evaluated by materials characterization obtained after galvanostatic electrolyses.展开更多
An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the den...An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the density and liquidus temperature of NaCl salt.The accuracy of the liquidus temperature measurement is about±1 K.The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%.The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF(46.5-11.5-42mol%)are investigated.展开更多
Two perovskite-type fluorides K2NaVF6 and （NH4）3VF6 were synthesized under mild hydrothermal con- ditions. The structures of the compounds were determined by means of powder X-ray diffraction analysis. The Riet- vel...Two perovskite-type fluorides K2NaVF6 and （NH4）3VF6 were synthesized under mild hydrothermal con- ditions. The structures of the compounds were determined by means of powder X-ray diffraction analysis. The Riet- veld refinement indicates that K2NaVF6 has a cubic elpasolite-type structure and crystallizes in space group Fm3m with lattice constant a=8.3180（2） nm. （NH4）3VF6 has a cubic cryolite-type structure and crystallizes in space group Fm3m with lattice parameter a=9.090（1） rim. The compounds were further characterized by scanning electron micro- scopy（SEM）, thermogravimetric（TG） and differential thermal analysis（DTA）. The variable temperature magnetic susceptibility of these two compounds was characterized for the first time and the result shows that the magnetic or- dering is related to the crystallographic features and isolated magnetic unit with the temperature decreasing.展开更多
Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long...Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long-time ball milling process with carbon,is necessary to achieve a high electrochemical performance.The most successful method to enhance electrochemical activity,carbon coating,seemed to be impracticable,so far,for sensitive fluorides like Li3 FeF6.In this work,carbon coating on Li3 FeF6 particles has been successfully achieved for the first time,while avoiding both extended hydrolysis and Fe(Ⅲ)-Fe(Ⅱ)reduction.The heat treatment and atmosphere,yielding the maximal transformation of organic carbon to both graphitised and disordered carbon,has been determined.Carbon coating,with a thickness of approximately 2.5 nm,has been achieved by controlled thermal decomposition of glucose,under air,at 300℃.Raman and X-ray photoelectron spectroscopy(XPS)experiments have proved the existence of carbon and Fe2O3 on the surface of Li3FeF6 nanoparticles.XPS spectroscopy indicates the presence of organic residues from glucose decomposition.Attempts to further reduce the orga nic carbon content results in a decrease of the amorphous carbon coating layer.Optimised carbon-coated Li3 FeF6 nanoparticles deliver 122 mA h g^(-1)(85%of theoretical capacity)significantly higher than that of a noncoated sample(58 mA h g^(-1)).Even more,a significant beneficial effect of carbon coating on both capacity retention and coulombic efficiency is observed.展开更多
Quasi-Newton, fully-connected, and feed forward neural network were used to study the correlation between the spectral structure of the Eu2+ ion in complex fluorides and the structures of complex fluorides. The experi...Quasi-Newton, fully-connected, and feed forward neural network were used to study the correlation between the spectral structure of the Eu2+ ion in complex fluorides and the structures of complex fluorides. The experimental results show that the neural network architecture (number of layers and number of nodes in each layer),the intial weights. and the organization of the data were all important factors affecting the performance of the neural network. The performance of the neural network was enhanced by adapting a test set to monitor the training process. Once trained, the neural network correctly classified 100% of the training set and 96.3% of the test set. These results offer tremendous improvement over previous pattern recognition methods.展开更多
High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unpa...High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.展开更多
基金Project supported by Polish Ministry of Science and Higher Education(Diamond Grant"Nr DI2011 011441)
文摘A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.
基金the financial support received from the China Scholarship Council(CSC)MERAGEM graduate school and the Ministry of Science,Research and Arts of the State of Baden-Wu rttemberg for funding research+4 种基金the support of the German Research Foundation(DFG)project(SE 1407/4-2)the support of the En ABLES,a project funded by the European Union’s Horizon 2020 research and innovation program under grant agreement(730957)the support of Epi Store project under grant agreement(101017709)the Centre for Electrochemical Energy Storage Ulm-Karlsruhe(CELEST)the support from the Karlsruhe Nano Micro Facility(KNMF)。
文摘With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.
基金the financial support from Liaoning Sci-ence and Technology Development Foundation Guided by Cen-tral Government(No.2021JH6/10500139)the Fundamental Research Funds for the Central Universities(No.N2205003)+2 种基金the financial support from the National Natural Science Foundation of China(No.52003007)Nat-ural Science Foundation of Hebei Province(No.E2019409063)Langfang top-notch talent(No.LFBJ202004).
文摘Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.
基金Project supported bythe National Natural Science Foundation of China (20401006)Natural Science Foundation of Henan Province (200510475019)
文摘Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.
基金Project supported by the National Natural Science Foundation of China (10774012, 10874014 and 10979009)
文摘The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...
基金financially supported by the National Natural Science Foundation of China(Nos.21502240,81972824)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515010684,2020A1515011513)Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(No.2019B030301005)。
文摘Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections.Sulfonyl fluorides,one of the most important sulfur(Ⅵ)fluoride species,have attracted enormous attention in diverse fields,ranging from organic synthesis and material science,to chemical biology and drug discovery.This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides,which include aromatic,aliphatic,alkenyl,and alkynyl sulfonyl fluorides.While not meant to be exhaustive,the purpose is to give a timely overview and insight in this field,and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.
基金Project supported by the Polish National Science Centre(2015/17/N/ST5/01947)
文摘Praseodymium（III） doped CeF3, CeF3：Gd, LaF3, GdF3 and YF3 inorganic fluorides were precipitated in an aqueous, sur- factant-free solution, using NH4F as a source of fluoride ions. The as-prepared products were subjected to a hydrothermal treatment, which led to the formation of crystalline nanoluminophores, composed of spherical （30 nm） and elongated （40-200 nm） nanos- tructures. Due to the presence of Pr3＋ ions, the synthesized nanomaterials showed yellow luminescence under a blue light irradiation. The nanoluminophore based on the YF3 host revealed the most promising spectroscopic properties, i.e., bright and intensive emission, hence it was investigated in detail. The photophysical properties of the nanomaterials obtained were studied by powder X-ray diffrac- tion （XRD）, transmission electron microscopy （TEM） and spectrofluorometry, i.e., measurements of excitation/emission spectra and luminescence decay curves.
基金Funded by the Natural Science Foundation of Shaanxi Province(No.2018JQ2057)Shaanxi Provincial Education Department(No.17JK0151)Ph D Research Foundation Project of Shaanxi University of Technology(No.209020195)
文摘Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TEM) was used to characterize the nanoparticles. The nanoparticles were modified by PEI, CTAB, PAA and Ci, respectively. It was feasible for function by -COOH and -NH2 groups, due to the surface modification. Moreover, different surface modifications of the nanoparticles were examined. The possible formation mechanisms for fluoride nanoparticles with surface modification were presented in detail. More importantly, it is expected to be widely applied to biomedicine.
基金the financial support from the National Natural Science Foundation of China (Nos. 21772147, 22071186, 22071187)Natural Science Foundation of Hubei Province (No. 2020CFA036)+1 种基金Natural Science Foundation of Jiangsu Province (No. SKB2019041078)The Program of Introducing Talents of Discipline to Universities of China (111 Project) is also appreciated。
文摘Cu-catalyzed endo-selective asymmetric 1,3-dipolar cycloaddition of azomethine ylides with ethenesulfonyl fluorides(ESFs) was successfully developed, this protocol provided an efficient and facile method to a wide range of chiral pyrrolidine-3-sulfonyl fluorides with good to excellent results(up to 87% yield,>20:1 dr, 94% ee). Some other chiral sulfonyl derivatives, such as sulfonamide and sulfonate, were easily accessible through simple transformations with high yields, which demonstrated that the cycloaddition products could be synthetically useful in the sulfur(VI) fluoride exchange(Su FEx) chemistry.
基金National Natural Science Foundation of China(No.21971228)for financial support。
文摘A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to success is the use of pyridine-oxazoline as ligand and(MeO)_(2)MeSiH as the hydrogen source.This transformation demonstrates high efficiency,mild conditions,good functional-group compatibility and great potential in the drug discovery.
文摘The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic voltammetry. The electrodeposited products were analysed by X ray diffraction. The results show that the electrolytic codeposition of Y Al alloy in the LiF YF 3 Y 2O 3 Al 2O 3 system without AlF 3 can be achieved at the same potential for Y(Ⅲ) and Al(Ⅲ) which have great difference in deposition potential. It is beneficial to codeposition of Y(Ⅲ) and Al(Ⅲ) when temperature rises. The potential of beginning codeposition is about -0.85 V ( vs Pt reference electrode), but only at the potential of -0.95 V or more negative can Y based Al alloy containing a great amount of yttrium be obtained.
基金supported by the Polish Ministry of Science and Higher Education under grant for statutory I-43
文摘The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H Vincent and D. Mark at the Institute of Occupational Medicine（IOM）, personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648 a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-Ntrimethylammonium bromide（CTAB） were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8 μg/L and 24 μg/L, respectively The linear range of calibration was 0.01–10 mg/L, which corresponds to 0.0001–0.1 mg of fluorides per m3 in collection of a 20 L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20–1.82 mg/m3, while the inhalable fraction contained 0.23–1.96 mg/m3 of fluorides during an eight-hour working day in the welding room.
文摘The thermodynamic and dynamic behaviour of Ni^(2+)|Ni couple in FLINAK melt is investigated by us- ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and a large exchange current density(6 mA·cm^(-2)).A single crystal LaF_3 which is a fluoride ion conductor used as a membrane of the Ni^(2+)|Ni couple reference electrode is reliable in FLINAK melts at 973 K.The poten- tial of LaF_3 membrane reference electrode is constant within±2 mV.The boron nitride used as a salt bridge was not good in FLINAK melts.The platinum electrode is studied by using micropolarization.The equilibrium potential of Pt electrode is dependent on the absorption and the electrochemical reaction.The potential is stable for a constant composition at constant temperature.
基金Project supported by the National Natural Science Foundation of China
文摘The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp line and its valence-state is stable.
文摘This article focuses on the electrorefining process in molten fluorides to selectively recover zirconium from one Zr-based metallic alloy involved in the field of nuclear energy: Zircaloy-4. Firstly, zirconium electrodeposition was investigated in molten LiF-NaF at 750˚C in order to determine appropriate operating conditions to ensure Zr metal recovery: concentration and applied current density. Then, anodic behaviour of Zircaloy-4 was studied and compared to its composing elements. These results allowed us to define an adapted electrorefining strategy. Electrorefining progress, anodic and cathodic faradic efficiencies were evaluated by materials characterization obtained after galvanostatic electrolyses.
文摘An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the density and liquidus temperature of NaCl salt.The accuracy of the liquidus temperature measurement is about±1 K.The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%.The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF(46.5-11.5-42mol%)are investigated.
基金Supported by the Science and Technology Development Planning of Jilin Province,China(Nos.20100116,201105005)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20100061120089)+1 种基金the Open Project of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(No.2011-01)the Open Project of State Key Laboratory of Superhard Materials(No.2011-04),China
文摘Two perovskite-type fluorides K2NaVF6 and （NH4）3VF6 were synthesized under mild hydrothermal con- ditions. The structures of the compounds were determined by means of powder X-ray diffraction analysis. The Riet- veld refinement indicates that K2NaVF6 has a cubic elpasolite-type structure and crystallizes in space group Fm3m with lattice constant a=8.3180（2） nm. （NH4）3VF6 has a cubic cryolite-type structure and crystallizes in space group Fm3m with lattice parameter a=9.090（1） rim. The compounds were further characterized by scanning electron micro- scopy（SEM）, thermogravimetric（TG） and differential thermal analysis（DTA）. The variable temperature magnetic susceptibility of these two compounds was characterized for the first time and the result shows that the magnetic or- dering is related to the crystallographic features and isolated magnetic unit with the temperature decreasing.
基金This work was financially supported by the“Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional”(FEDER/UE)and“Comunidad de Madrid”(Nos.MAT2016-78632-C4-1-R and S2013/MIT-2753)Characterisation techniques for this research were partially financed by the EU funds(Nos.POPW.01.03.00-20.034/09-00 and POPW.01.03.00-20-004/11-00)。
文摘Li_(3)FeF_(6)has been the focus of research of fluorine-based cathode materials for lithium-ion batteries.Because of the low electronic conductivity of Li3 FeF6,the decrease of particle size,by an energyconsuming long-time ball milling process with carbon,is necessary to achieve a high electrochemical performance.The most successful method to enhance electrochemical activity,carbon coating,seemed to be impracticable,so far,for sensitive fluorides like Li3 FeF6.In this work,carbon coating on Li3 FeF6 particles has been successfully achieved for the first time,while avoiding both extended hydrolysis and Fe(Ⅲ)-Fe(Ⅱ)reduction.The heat treatment and atmosphere,yielding the maximal transformation of organic carbon to both graphitised and disordered carbon,has been determined.Carbon coating,with a thickness of approximately 2.5 nm,has been achieved by controlled thermal decomposition of glucose,under air,at 300℃.Raman and X-ray photoelectron spectroscopy(XPS)experiments have proved the existence of carbon and Fe2O3 on the surface of Li3FeF6 nanoparticles.XPS spectroscopy indicates the presence of organic residues from glucose decomposition.Attempts to further reduce the orga nic carbon content results in a decrease of the amorphous carbon coating layer.Optimised carbon-coated Li3 FeF6 nanoparticles deliver 122 mA h g^(-1)(85%of theoretical capacity)significantly higher than that of a noncoated sample(58 mA h g^(-1)).Even more,a significant beneficial effect of carbon coating on both capacity retention and coulombic efficiency is observed.
文摘Quasi-Newton, fully-connected, and feed forward neural network were used to study the correlation between the spectral structure of the Eu2+ ion in complex fluorides and the structures of complex fluorides. The experimental results show that the neural network architecture (number of layers and number of nodes in each layer),the intial weights. and the organization of the data were all important factors affecting the performance of the neural network. The performance of the neural network was enhanced by adapting a test set to monitor the training process. Once trained, the neural network correctly classified 100% of the training set and 96.3% of the test set. These results offer tremendous improvement over previous pattern recognition methods.
基金P.G.acknowledges the financial support from the Youth Foundation of Shandong Natural Science Foundation(No.ZR2023OB230)National Natural Science Foundation(No.22309035)Double First-class Discipline Construction Fund Project of Harbin Institute of Technology at Weihai(No.2023SYLHY11).
文摘High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.
