The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low loss optical wave guides, have been measured by standard archimedes method and by using as Pulfri...The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low loss optical wave guides, have been measured by standard archimedes method and by using as Pulfrich refractometer respectively. The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant. The refractive index as a function of composition is also calculated, based on the Lorenz Lorentz equation, by computing the electronic polarizability of HMF glasses. All calculated results are in good agreement with the observed data.展开更多
As the most successful new energy storage device developed in recent decades,lithium-ion batteries(LIBs)are ubiquitous in the modern society.However,current commercial LIBs comprising mainly intercalated cathode mater...As the most successful new energy storage device developed in recent decades,lithium-ion batteries(LIBs)are ubiquitous in the modern society.However,current commercial LIBs comprising mainly intercalated cathode materials are limited by the theoretical energy density which cannot meet the high storing energy demanded by renewable applications.Compared to intercalation-type cathode materials,low-cost conversion-type cathode materials with a high theoretical specific capacity are expected to boost the overall energy of LIBs.Among the different conversion cathode materials,metal fluorides have become a popular research subject for their environmental friendliness,low toxicity,wide voltage range,and high theoretical specific capacity.In this review,we compare the energy storage performance of intercalation and conversion cathode materials based on thermodynamic calculation and summarize the main challenges.The common conversion-type cathode materials are described and their respective reaction mechanisms are discussed.In particular,the structural flaws and corresponding solutions and strategies are described.Finally,we discussed the prospective of metal fluorides and other conversion cathode materials to guide further research in this important field.展开更多
Exploring high‐energy density rechargeable lithium(Li)batteries is urgently needed to meet the demand of the large‐scale electric vehicle market.Conversion‐type metal fluorides(MFx)have been considered as desirable...Exploring high‐energy density rechargeable lithium(Li)batteries is urgently needed to meet the demand of the large‐scale electric vehicle market.Conversion‐type metal fluorides(MFx)have been considered as desirable cathode materials for next‐generation rechargeable batteries because of their high operational voltages,environmental non‐toxicity,low cost,and high thermal stability.In this review,we present the most promising and feasible MFx applied in rechargeable Li batteries in terms of capacity,discharge po-tential,volume change,fabricated methods,crystal structure,and cost/abun-dance.The electrochemical performance is briefly illustrated,and the recent advances in mechanisms focused on MFx cathodes upon cyclic processes are noted and discussed in detail.Finally,prospects for the current challenges and possible research directions,with the aim to provide some inspiration for the development of MFx‐based cathodes are presented.展开更多
This paper studies the properties of fluoride glasses for use in particle calorimeters or in optical fibers. The effects of major and minor impurities in manufacturing process and ultimately on the glass properties ha...This paper studies the properties of fluoride glasses for use in particle calorimeters or in optical fibers. The effects of major and minor impurities in manufacturing process and ultimately on the glass properties have been investigated. Glasses in a range of compositions have been made and tested in the form of small samples as well as larger blocks of size 2×3×14 cm 3. Results of measurements on these materials, using a high energy particle beam, are presented.展开更多
Performance boosting of hybrid metal oxide and metal alloy catalyst is crucial to the water electrolysis for hydrogen generation. Herein, a novel concept of selective fluoridation of metal alloy/oxide hybrid is propos...Performance boosting of hybrid metal oxide and metal alloy catalyst is crucial to the water electrolysis for hydrogen generation. Herein, a novel concept of selective fluoridation of metal alloy/oxide hybrid is proposed to boost their catalytic performance for the oxygen evolution reaction(OER). A well-recognized OER catalyst system of FeNi3 alloy/oxide embedded in nitrogen-doped porous nanofibers(FeNiO/NCF) is employed as a proof of concept, and it is selectively fluoridated by transforming the metal oxide to metal fluoride(FeNiF/NCF). The crystal structure and surface chemical state transformation are well supported by the spectroscopic analysis and the improved electrochemical performance for OER can be well correlated to the phase and structure change. Specifically, FeNiF/NCF can drive the benchmark current density of 10 mA cm-2 at 260 mV with a Tafel slope of 67 mV dec-1, about 70 mV less than that of FeNiO/NCF.Increased catalytic kinetics, rapid charge transfer ability, high catalytic efficiency and stability are also probed by electrochemical analysis. The high surface area and roughness are found mainly generated via the high-temperature annealing for the metal alloy/metal oxide formation, and the low-temperature fluoridation process intrinsically contributes to the active structure formation. It is an efficient and universal approach to increase the catalytic performance of metal alloy/oxide for energy-relevant catalytic reactions.展开更多
Up-conversion processes for the blue, green and red emissions were foundtwo-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd^(3+)→ Yb^(3+) → Ho^(3+) energy transfer. The str...Up-conversion processes for the blue, green and red emissions were foundtwo-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd^(3+)→ Yb^(3+) → Ho^(3+) energy transfer. The strong green emission due to the Ho^(3+) : (~5F_4, ~5S_2)→ ~5I_8 transitions was observed in Nd^(3+) - Ho^(3+) co-doped ZrF_4-based fluoride glasses under800 nm excitation. As an attempt to enhance Ho^(3+) up-conversion luminescences in the Nd^(3+) -Ho^(3+) co-doped ZrF_4-based glasses, Yb^(3+) ions were added to the glasses. As a result it wasfound that, in 800 nm excitation of 60ZrF_4. 30BaF2. (8-x)LaF_3. 1NdF_3. xYbF_3. 1HoF_3 glasses (x =0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm(green), and 650 nm (red), which correspond to the Ho^(3+) : ~5F_3 → ~5I_8, ( ~5F_4, ~5S_2) →~5I_8 and ~5F_5 → ~5I_8 transitions respectively. The intensities of the green and red emissions ina 3 mol% YbF_3-containing glass were about 50 times stronger than those glasses without YbF_3. Thisis based on sensitization due to Yb^(3+) ions. In particular, the green emission was extremelystrong and the Nd^(3+) - Yb^(3+) - Ho^(3+) co-doped ZrF_4-based glasses have a high possibility ofrealizing a green up-conversion laser glass. In this paper the up-conversion mechanism in theglasses is discussed in detail.展开更多
Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. T...Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides-MF2（M=Sr, Mg, Ca） on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.展开更多
Iron fluoride(FeF_(3)) is considered as a promising cathode material for Li-ion batteries(LIBs)due to its high theoretical capacity(712 mAh/g)with a 3 e-transfer.Herein,we have designed a strategy of hierarchical and ...Iron fluoride(FeF_(3)) is considered as a promising cathode material for Li-ion batteries(LIBs)due to its high theoretical capacity(712 mAh/g)with a 3 e-transfer.Herein,we have designed a strategy of hierarchical and mesoporous FeF_(3)/rG O hybrids for LIBs,where the hollow Fe F_(3) nanospheres are the main contributor to the specific capacity and the 2 D r GO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion.The unique FeF_(3)/rGO hybrid can be rationally synthesized by a nonaqueous in-situ precipitation method,offering the merits of large specific surface area with rich active sites,fast transport channels for lithium ions,effective alleviation of volume expansion during cycles,and accelerating the electrochemical reaction kinetics.The Fe F_(3)/r GO hybrid electrode possesses a high initial discharge capacity of 553.9 m Ah/g at a rate of 0.5 C with 378 m Ah/g after 100 cycles,acceptable rate capability with 168 m Ah/g at 2 C,and feasible high-temperature operation(320 m Ah/g at 70℃).The superior electrochemical behaviors presented here demonstrates that the FeF_(3)/rGO hybrid is a potential electrode for LIBs,which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.展开更多
Phase diagrams for the CsF-UF4 and CsF-ThF4 systems were modeled in the present work through computational thennodynamics. The associate solution model with various complex species（CsMFs, Cs2MF6 and Cs3MF7; M=Th, U）...Phase diagrams for the CsF-UF4 and CsF-ThF4 systems were modeled in the present work through computational thennodynamics. The associate solution model with various complex species（CsMFs, Cs2MF6 and Cs3MF7; M=Th, U） was used to thermodynamically describe the binary molten salts. A total of ten intermediate phases were treated as stoichiometric compounds with their Gibbs energies modeled according to the Neumann-Kopp rule. All these model parameters were optimized by the least squares procedure until good coincidence was achieved between the calculated results and most of the experimental data. The derived thermodynamic parameters will be merged into the multicomponent CsF-LiF-BeF2-ThF4-UF4 database for analyzing physicochemical behavior of CsF in the fuel salt of the molten salt breeder reactor.展开更多
The upconversion（UC） of the rare earth doped glass-ceramics has been extensively investigated due to their potential applications in many fields, such as color display, high density memories, optical data storage, s...The upconversion（UC） of the rare earth doped glass-ceramics has been extensively investigated due to their potential applications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the oxyfluorides glasses containing Ba2 LaF 7 nanocrystals were studied in this review work, due to the thermal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. Moreover, the energy transfer（ET） between the rare earth ions and transition metals plays an important role in the upconversion process. The cooperative ET has been researched very activly in UC glasses due to applications in the fields of solar cells, such as in the Er/Yb, Tm/Yb, Tb/Yb, Tb/Er/Yb and Tm/Er/Yb couples. The present article reviews on the recent progress made on：（i） upconversion materials with fluoride microcrystals in glasses and the mechanisms involved, including the UC in double and tri-dopant RE ions activated fluoride microcrystal, energy transfer process; and（ii） the effect of the metal Mn and nanoparticles of Au, Ag, Cu on the enhancement of UC emissions. Discussions have also been made on materials, material synthesis, the structural and emission properties of glass-ceramics. Additionally, the conversion efficiency is still a challenge for the spectra conversion materials and application; challenge and future advances have also been demonstrated.展开更多
文摘The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low loss optical wave guides, have been measured by standard archimedes method and by using as Pulfrich refractometer respectively. The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant. The refractive index as a function of composition is also calculated, based on the Lorenz Lorentz equation, by computing the electronic polarizability of HMF glasses. All calculated results are in good agreement with the observed data.
文摘As the most successful new energy storage device developed in recent decades,lithium-ion batteries(LIBs)are ubiquitous in the modern society.However,current commercial LIBs comprising mainly intercalated cathode materials are limited by the theoretical energy density which cannot meet the high storing energy demanded by renewable applications.Compared to intercalation-type cathode materials,low-cost conversion-type cathode materials with a high theoretical specific capacity are expected to boost the overall energy of LIBs.Among the different conversion cathode materials,metal fluorides have become a popular research subject for their environmental friendliness,low toxicity,wide voltage range,and high theoretical specific capacity.In this review,we compare the energy storage performance of intercalation and conversion cathode materials based on thermodynamic calculation and summarize the main challenges.The common conversion-type cathode materials are described and their respective reaction mechanisms are discussed.In particular,the structural flaws and corresponding solutions and strategies are described.Finally,we discussed the prospective of metal fluorides and other conversion cathode materials to guide further research in this important field.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFB2502000National Natural Science Foundation of China,Grant/Award Numbers:22109137,51972285,52225208,U21A20174Leading nonnative and Entrepreneur Team introduction Program of Zhejiang,Grant/Award Number:2020R01002。
文摘Exploring high‐energy density rechargeable lithium(Li)batteries is urgently needed to meet the demand of the large‐scale electric vehicle market.Conversion‐type metal fluorides(MFx)have been considered as desirable cathode materials for next‐generation rechargeable batteries because of their high operational voltages,environmental non‐toxicity,low cost,and high thermal stability.In this review,we present the most promising and feasible MFx applied in rechargeable Li batteries in terms of capacity,discharge po-tential,volume change,fabricated methods,crystal structure,and cost/abun-dance.The electrochemical performance is briefly illustrated,and the recent advances in mechanisms focused on MFx cathodes upon cyclic processes are noted and discussed in detail.Finally,prospects for the current challenges and possible research directions,with the aim to provide some inspiration for the development of MFx‐based cathodes are presented.
文摘This paper studies the properties of fluoride glasses for use in particle calorimeters or in optical fibers. The effects of major and minor impurities in manufacturing process and ultimately on the glass properties have been investigated. Glasses in a range of compositions have been made and tested in the form of small samples as well as larger blocks of size 2×3×14 cm 3. Results of measurements on these materials, using a high energy particle beam, are presented.
基金supported by the National Natural Science Foundation of China (21603041 and 21972124)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionthe support of Six Talent Peaks Project of Jiangsu Province (XCL-070-2018)。
文摘Performance boosting of hybrid metal oxide and metal alloy catalyst is crucial to the water electrolysis for hydrogen generation. Herein, a novel concept of selective fluoridation of metal alloy/oxide hybrid is proposed to boost their catalytic performance for the oxygen evolution reaction(OER). A well-recognized OER catalyst system of FeNi3 alloy/oxide embedded in nitrogen-doped porous nanofibers(FeNiO/NCF) is employed as a proof of concept, and it is selectively fluoridated by transforming the metal oxide to metal fluoride(FeNiF/NCF). The crystal structure and surface chemical state transformation are well supported by the spectroscopic analysis and the improved electrochemical performance for OER can be well correlated to the phase and structure change. Specifically, FeNiF/NCF can drive the benchmark current density of 10 mA cm-2 at 260 mV with a Tafel slope of 67 mV dec-1, about 70 mV less than that of FeNiO/NCF.Increased catalytic kinetics, rapid charge transfer ability, high catalytic efficiency and stability are also probed by electrochemical analysis. The high surface area and roughness are found mainly generated via the high-temperature annealing for the metal alloy/metal oxide formation, and the low-temperature fluoridation process intrinsically contributes to the active structure formation. It is an efficient and universal approach to increase the catalytic performance of metal alloy/oxide for energy-relevant catalytic reactions.
文摘Up-conversion processes for the blue, green and red emissions were foundtwo-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd^(3+)→ Yb^(3+) → Ho^(3+) energy transfer. The strong green emission due to the Ho^(3+) : (~5F_4, ~5S_2)→ ~5I_8 transitions was observed in Nd^(3+) - Ho^(3+) co-doped ZrF_4-based fluoride glasses under800 nm excitation. As an attempt to enhance Ho^(3+) up-conversion luminescences in the Nd^(3+) -Ho^(3+) co-doped ZrF_4-based glasses, Yb^(3+) ions were added to the glasses. As a result it wasfound that, in 800 nm excitation of 60ZrF_4. 30BaF2. (8-x)LaF_3. 1NdF_3. xYbF_3. 1HoF_3 glasses (x =0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm(green), and 650 nm (red), which correspond to the Ho^(3+) : ~5F_3 → ~5I_8, ( ~5F_4, ~5S_2) →~5I_8 and ~5F_5 → ~5I_8 transitions respectively. The intensities of the green and red emissions ina 3 mol% YbF_3-containing glass were about 50 times stronger than those glasses without YbF_3. Thisis based on sensitization due to Yb^(3+) ions. In particular, the green emission was extremelystrong and the Nd^(3+) - Yb^(3+) - Ho^(3+) co-doped ZrF_4-based glasses have a high possibility ofrealizing a green up-conversion laser glass. In this paper the up-conversion mechanism in theglasses is discussed in detail.
基金the ＂Qimingxing＂ Project （No. 04QMX1448） of Shanghai Municipal Science and Technology Commission the National Natural Science Foundation of China （Grant No. 50572110）.
文摘Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides-MF2（M=Sr, Mg, Ca） on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.
基金financially supported by National Natural Science Foundation of China(No.U20A20209)Zhejiang Provincial Key Research and Development Program(No.2021C01030)+1 种基金Zhejiang Provincial Natural Science Foundation of China(No.LD19E020001)Open Project of Laboratory for Biomedical Engineering of Ministry of Education,Zhejiang University。
文摘Iron fluoride(FeF_(3)) is considered as a promising cathode material for Li-ion batteries(LIBs)due to its high theoretical capacity(712 mAh/g)with a 3 e-transfer.Herein,we have designed a strategy of hierarchical and mesoporous FeF_(3)/rG O hybrids for LIBs,where the hollow Fe F_(3) nanospheres are the main contributor to the specific capacity and the 2 D r GO nanosheets are the matrix elevating the electronic conductivity and buffering the volume expansion.The unique FeF_(3)/rGO hybrid can be rationally synthesized by a nonaqueous in-situ precipitation method,offering the merits of large specific surface area with rich active sites,fast transport channels for lithium ions,effective alleviation of volume expansion during cycles,and accelerating the electrochemical reaction kinetics.The Fe F_(3)/r GO hybrid electrode possesses a high initial discharge capacity of 553.9 m Ah/g at a rate of 0.5 C with 378 m Ah/g after 100 cycles,acceptable rate capability with 168 m Ah/g at 2 C,and feasible high-temperature operation(320 m Ah/g at 70℃).The superior electrochemical behaviors presented here demonstrates that the FeF_(3)/rGO hybrid is a potential electrode for LIBs,which may open up a new vision to design high-efficiency energy-storage devices such as LIBs based on transition metal fluorides.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences（No.XD02002400） and the National Natural Science Foundation of China（No.21473234）.
文摘Phase diagrams for the CsF-UF4 and CsF-ThF4 systems were modeled in the present work through computational thennodynamics. The associate solution model with various complex species（CsMFs, Cs2MF6 and Cs3MF7; M=Th, U） was used to thermodynamically describe the binary molten salts. A total of ten intermediate phases were treated as stoichiometric compounds with their Gibbs energies modeled according to the Neumann-Kopp rule. All these model parameters were optimized by the least squares procedure until good coincidence was achieved between the calculated results and most of the experimental data. The derived thermodynamic parameters will be merged into the multicomponent CsF-LiF-BeF2-ThF4-UF4 database for analyzing physicochemical behavior of CsF in the fuel salt of the molten salt breeder reactor.
基金Project supported by the National Natural Science Foundation of China(61307111,51272097,61265004)Ningbo Natural Science Foundation(2015A610079)+1 种基金Ningbo University Science Research Fund Project(XYL15022)General Project of Zhejiang Provincial Department of Education(Y201533345)
文摘The upconversion（UC） of the rare earth doped glass-ceramics has been extensively investigated due to their potential applications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the oxyfluorides glasses containing Ba2 LaF 7 nanocrystals were studied in this review work, due to the thermal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. Moreover, the energy transfer（ET） between the rare earth ions and transition metals plays an important role in the upconversion process. The cooperative ET has been researched very activly in UC glasses due to applications in the fields of solar cells, such as in the Er/Yb, Tm/Yb, Tb/Yb, Tb/Er/Yb and Tm/Er/Yb couples. The present article reviews on the recent progress made on：（i） upconversion materials with fluoride microcrystals in glasses and the mechanisms involved, including the UC in double and tri-dopant RE ions activated fluoride microcrystal, energy transfer process; and（ii） the effect of the metal Mn and nanoparticles of Au, Ag, Cu on the enhancement of UC emissions. Discussions have also been made on materials, material synthesis, the structural and emission properties of glass-ceramics. Additionally, the conversion efficiency is still a challenge for the spectra conversion materials and application; challenge and future advances have also been demonstrated.
