Britholite-Y is milkwhite, rosy in colour. The measured specific gravity is 4.35, with Ng′ = 1.791, Np′ = 1.784. As determined by electron microprobe, its crystal formula is (Y2.82Ca1.58Ce0.27Dy0.21Er0.11)5 [(Si2.95...Britholite-Y is milkwhite, rosy in colour. The measured specific gravity is 4.35, with Ng′ = 1.791, Np′ = 1.784. As determined by electron microprobe, its crystal formula is (Y2.82Ca1.58Ce0.27Dy0.21Er0.11)5 [(Si2.95P0.05)3O12](OH,F), space group = C22-P21, a = (0.9504±0.0005) nm, b = (0.9414±0.0004) nm, c = (0.6922±0.0002) nm, r = (119.71±0.04)°, V = (53.79±0.04) nm3, Z = 2. Least-squares refinements with 2272 independent reflection (F0>3σ|F0|) yielded R = 0.111. The change of symmetry group P63/m of apatite to P21 of britholite-Y results from the shifts of Y, Ca, Si, O and (OH) atoms (anions) from the pseudohexagonal P63/m equivalent positions (6h), (4f), (12i) and (2a) as produced by distortion of the polyhedra with 7-, 9-, and 4-corners. The substitution of Ca in apatite for Y and the order distribution of atoms Y and Ca on the equivalent positions (6h) and (4f) have contributed to the distortion of 7- and 9- cornered polyhedra. The substitutions of Si4+ for P5+ and OH- for F- may also be effected. The crystal chemistry of apatite-group minerals is also discussed.展开更多
Ni-rich layered cathodes have become the promising candidates for the next-generation high-energy Liion batteries due to their high energy density and competitive cost.However,they suffer from rapidcapacity fading due...Ni-rich layered cathodes have become the promising candidates for the next-generation high-energy Liion batteries due to their high energy density and competitive cost.However,they suffer from rapidcapacity fading due to the structural and interfacial instability upon long-term operation.Herein,the Tidoped and LiYO2-coated Ni-rich layered cathode has been synthesized via a facile one-step sinteringstrategy,which significantly restrains the interfacial parasitic side reactions and enhances the structuralstability.Specifically,the trace Ti^(4+)doping greatly stabilizes the lattice oxygen and alleviates the Li/Nidisorder while the LiYO_(2) coating layer can prevent the erosion of the cathode by the electrolyte duringcycles.As a result,the Ti-NCM83@LYO delivers a high specific capacity of 135 mAh g^(-1) even at 10C andthere is almost no capacity loss at 1C for 100 cycles.This work provides a simple one-step dual-modification strategy to meet the commercial requirements of Ni-rich cathodes.展开更多
The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recover...The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recovered even for 2πultrashort pulses. New features such as pulse splitting, red-shift and blue-shift of the corresponding spectra arise, and the component of central frequency gradually disappears.展开更多
文摘Britholite-Y is milkwhite, rosy in colour. The measured specific gravity is 4.35, with Ng′ = 1.791, Np′ = 1.784. As determined by electron microprobe, its crystal formula is (Y2.82Ca1.58Ce0.27Dy0.21Er0.11)5 [(Si2.95P0.05)3O12](OH,F), space group = C22-P21, a = (0.9504±0.0005) nm, b = (0.9414±0.0004) nm, c = (0.6922±0.0002) nm, r = (119.71±0.04)°, V = (53.79±0.04) nm3, Z = 2. Least-squares refinements with 2272 independent reflection (F0>3σ|F0|) yielded R = 0.111. The change of symmetry group P63/m of apatite to P21 of britholite-Y results from the shifts of Y, Ca, Si, O and (OH) atoms (anions) from the pseudohexagonal P63/m equivalent positions (6h), (4f), (12i) and (2a) as produced by distortion of the polyhedra with 7-, 9-, and 4-corners. The substitution of Ca in apatite for Y and the order distribution of atoms Y and Ca on the equivalent positions (6h) and (4f) have contributed to the distortion of 7- and 9- cornered polyhedra. The substitutions of Si4+ for P5+ and OH- for F- may also be effected. The crystal chemistry of apatite-group minerals is also discussed.
基金This work was supported by the National Natural ScienceFoundation of China(grant No.21975074)the Innovation Programof Shanghai Municipal Education Commission,and the Fundamental Research Funds for the Central Universities.
文摘Ni-rich layered cathodes have become the promising candidates for the next-generation high-energy Liion batteries due to their high energy density and competitive cost.However,they suffer from rapidcapacity fading due to the structural and interfacial instability upon long-term operation.Herein,the Tidoped and LiYO2-coated Ni-rich layered cathode has been synthesized via a facile one-step sinteringstrategy,which significantly restrains the interfacial parasitic side reactions and enhances the structuralstability.Specifically,the trace Ti^(4+)doping greatly stabilizes the lattice oxygen and alleviates the Li/Nidisorder while the LiYO_(2) coating layer can prevent the erosion of the cathode by the electrolyte duringcycles.As a result,the Ti-NCM83@LYO delivers a high specific capacity of 135 mAh g^(-1) even at 10C andthere is almost no capacity loss at 1C for 100 cycles.This work provides a simple one-step dual-modification strategy to meet the commercial requirements of Ni-rich cathodes.
基金The work was supported by the National Natural Science Foundation of China (No. 60478002) and the Natural Science Key Foundation of Shanghai (No. 04JC14036).
文摘The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recovered even for 2πultrashort pulses. New features such as pulse splitting, red-shift and blue-shift of the corresponding spectra arise, and the component of central frequency gradually disappears.
