Diglycolamides(DGAs) show excellent application prospects for the extraction and separation of rare earth metals from highly radioactive liquid wastes and rare earth ores.The extraction ability of DGAs for rare earth ...Diglycolamides(DGAs) show excellent application prospects for the extraction and separation of rare earth metals from highly radioactive liquid wastes and rare earth ores.The extraction ability of DGAs for rare earth ions in nitrate or chloride media increases with increasing atomic number of the rare earth metal.To understand the origin of this phenomenon,three binuclear crystals [Ln(TEDGA)_(3)][Ln(NO_(3))_(6)] of N,N,N’,N’-tetraethyldiglycolamide(TEDGA) with rare earth ions La(Ⅲ),Pr(Ⅲ) and Eu(III) were prepared and characterized crystallographically.The three complexes belong to the triclinic crystal system,P-1 space group.The bond lengths of Ln-O_(amide) are significantly shorter than those of Ln-O_(ether) in the same crystal.The Ln-O_(amide) and Ln-O_(enher) bond lengths gradually decrease with increasing atomic number of the rare earth ion.The dihedral angle formed by TEDGA and metal ions through the tridentate coordination gradually increases with increasing metal ion atomic number,tending toward the formation of sizeable planar coordination structures for the most massive rare earth ions.The structures of the compounds formed by the extractant and metal ion were optimized by means of DFT simulations.We find that the interaction between TEDGA and the rare earth ion is dominated by electrostatic interaction by analyzing binding energy,WBIs,Mulliken charge,natural electron configurations,and molecular orbital interaction.The covalent component of the Ln-O bonds of the complexes increases with increasing metal atomic number.The observed increase in extraction and separation capacity of diglycolamides for rare earth ions with increasing atomic number might be due to the formation of two fivemember rings by one tridentate ligand.The rare earth ions with large atomic numbers tend to form planar structures with large dihedral angles with DGA ligands.展开更多
Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type...Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type anodes.Currently,the large-scale extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)by traditional metallurgical routes highly relies on using reducing agents(e.g.,carbon,hydrogen,reactive metals),which consumes a large number of fossil fuels and produces greenhouse gas emissions.In addition,the common metallurgical methods for extracting semimetals involve relatively high operating temperatures and therefore produce bulk metal ingots solidified from the liquid metals.However,the commonly used electrode materials in batteries are fine powders.Thus,directly producing semimetal powders would be more energy efficient.In addition,semimetals are good candidates to host alkali/alkaline-earth ions through the alloying process because the electronegativity of semimetals is high.Therefore,preparing semimetal powders via an environment-sound manner is of great interest to provide sustainable anode materials for MIBs while reducing the ecological footprint.Low-cost and high-output capacity anode powder materials,as well as straightforward and environmental-benign synthetic methods,play key roles in enabling the energy conversion and storage technologies for real applications of MIBs.Electrochemical technologies offer new strategies to extract semimetals using electrons as the reducing agent that comes from renewable energies.Besides,the morphologies and structures of the electrolytic products can be rationally tailored by tuning the electrode potentials,electrolytes,and operating temperatures.In this regard,using the one-step green electrochemical method to prepare high-capacity and cheaper alloy-type metalloids for MIB anodes can fulfill the requirements for developing MIBs.This review critically overviews recent developments and advances in the electrochemical extraction of semimetals(Si,Ge)and se展开更多
Automatic extraction of road and linear structure from remote sensing images is a very important problem. This paper analyses several existing methods of the automatic road and linear structure extraction by using som...Automatic extraction of road and linear structure from remote sensing images is a very important problem. This paper analyses several existing methods of the automatic road and linear structure extraction by using some multi-spectral remote sensing images acquired from different spatial resolutions, districts and road characteristics. Their advantages and disadvantages have been generalized.展开更多
基金Project supported by the National Natural Science Foundation of China(21876062)。
文摘Diglycolamides(DGAs) show excellent application prospects for the extraction and separation of rare earth metals from highly radioactive liquid wastes and rare earth ores.The extraction ability of DGAs for rare earth ions in nitrate or chloride media increases with increasing atomic number of the rare earth metal.To understand the origin of this phenomenon,three binuclear crystals [Ln(TEDGA)_(3)][Ln(NO_(3))_(6)] of N,N,N’,N’-tetraethyldiglycolamide(TEDGA) with rare earth ions La(Ⅲ),Pr(Ⅲ) and Eu(III) were prepared and characterized crystallographically.The three complexes belong to the triclinic crystal system,P-1 space group.The bond lengths of Ln-O_(amide) are significantly shorter than those of Ln-O_(ether) in the same crystal.The Ln-O_(amide) and Ln-O_(enher) bond lengths gradually decrease with increasing atomic number of the rare earth ion.The dihedral angle formed by TEDGA and metal ions through the tridentate coordination gradually increases with increasing metal ion atomic number,tending toward the formation of sizeable planar coordination structures for the most massive rare earth ions.The structures of the compounds formed by the extractant and metal ion were optimized by means of DFT simulations.We find that the interaction between TEDGA and the rare earth ion is dominated by electrostatic interaction by analyzing binding energy,WBIs,Mulliken charge,natural electron configurations,and molecular orbital interaction.The covalent component of the Ln-O bonds of the complexes increases with increasing metal atomic number.The observed increase in extraction and separation capacity of diglycolamides for rare earth ions with increasing atomic number might be due to the formation of two fivemember rings by one tridentate ligand.The rare earth ions with large atomic numbers tend to form planar structures with large dihedral angles with DGA ligands.
基金the National Natural Science Foundation of China(No.51704060)the Fundamental Research Funds for the Central Universities(No.N172505002)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B16009)。
文摘Alloy-type metals/alloys hold the promise of increasing the energy density of metal-ion batteries(MIBs)because of their theoretical high gravimetrical capacities.Semimetals and semimetal-analogs are typical alloy-type anodes.Currently,the large-scale extraction of semimetals(Si,Ge)and semimetal-analogs(Sb,Bi,Sn)by traditional metallurgical routes highly relies on using reducing agents(e.g.,carbon,hydrogen,reactive metals),which consumes a large number of fossil fuels and produces greenhouse gas emissions.In addition,the common metallurgical methods for extracting semimetals involve relatively high operating temperatures and therefore produce bulk metal ingots solidified from the liquid metals.However,the commonly used electrode materials in batteries are fine powders.Thus,directly producing semimetal powders would be more energy efficient.In addition,semimetals are good candidates to host alkali/alkaline-earth ions through the alloying process because the electronegativity of semimetals is high.Therefore,preparing semimetal powders via an environment-sound manner is of great interest to provide sustainable anode materials for MIBs while reducing the ecological footprint.Low-cost and high-output capacity anode powder materials,as well as straightforward and environmental-benign synthetic methods,play key roles in enabling the energy conversion and storage technologies for real applications of MIBs.Electrochemical technologies offer new strategies to extract semimetals using electrons as the reducing agent that comes from renewable energies.Besides,the morphologies and structures of the electrolytic products can be rationally tailored by tuning the electrode potentials,electrolytes,and operating temperatures.In this regard,using the one-step green electrochemical method to prepare high-capacity and cheaper alloy-type metalloids for MIB anodes can fulfill the requirements for developing MIBs.This review critically overviews recent developments and advances in the electrochemical extraction of semimetals(Si,Ge)and se
文摘Automatic extraction of road and linear structure from remote sensing images is a very important problem. This paper analyses several existing methods of the automatic road and linear structure extraction by using some multi-spectral remote sensing images acquired from different spatial resolutions, districts and road characteristics. Their advantages and disadvantages have been generalized.
