The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0～3.3)...The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0～3.3), then diffused and crystallized by annealing at 650℃ for 10 min. The film without Nd layer showed soft magnetic behavior and high content of a-Fe phase. The films with R > =1 showed good hard magnetic properties with the high coercivity of about 20 kOe.展开更多
Helium is the second most abundant element in the universe, and together with silica, they are important components of giant planets. Exploring the reactivity and state of helium and silica under high pressure is cruc...Helium is the second most abundant element in the universe, and together with silica, they are important components of giant planets. Exploring the reactivity and state of helium and silica under high pressure is crucial for understanding of the evolution and internal structure of giant planets. Here, using first-principles calculations and crystal structure predictions, we identify four stable phases of a helium-silica compound with seven/eight-coordinated silicon atoms at pressure of 600–4000 GPa, corresponding to the interior condition of the outer planets in the solar system. The density of He Si O2 agrees with current structure models of the planets.This helium-silica compound exhibits a superionic-like helium diffusive state under the high-pressure and hightemperature conditions along the isentropes of Saturn, a metallic fluid state in Jupiter, and a solid state in the deep interiors of Uranus and Neptune. These results show that helium may affect the erosion of the rocky core in giant planets and may help to form a diluted core region, which not only highlight the reactivity of helium under high pressure but also provide evidence helpful for building more sophisticated interior models of giant planets.展开更多
Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poo...Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poor electronic conductivity of TMPs,the poor-rate capability,and fast capacity decay greatly hinder its practical application.To address these issues,a low-cost and facile strategy for the synthesis of Ni,N-codoped graphitized carbon(C)and cobalt phosphide(CoP)embedded in carbon fiber(Ni-CoP@CN⊂CF)as self-supporting anode material is demonstrated for the first time.The graphitized carbon and carbon fiber improve the electrical conductivity and inhibit the volume expansion issues.In addition to that,the microporous structure,and ultrasmall sized Ni-CoP offer a high surface area for electrolyte wettability,short Na-ion diffusion path and fast charge transport kinetics.As a result,outstanding electrochemical performance with an average capacity decay of 0.04%cycle^(−1)at 2000 mA g^(−1),an excellent rate capability of 270 mAh g^(−1)@2000 mA g^(−1)and a high energy density of~231.1 Wh kg^(−1)is achieved with binder-free self-supporting anode material.This work shows a potential for designing binder-free and high energy density sodium-ion batteries.展开更多
文摘The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0～3.3), then diffused and crystallized by annealing at 650℃ for 10 min. The film without Nd layer showed soft magnetic behavior and high content of a-Fe phase. The films with R > =1 showed good hard magnetic properties with the high coercivity of about 20 kOe.
基金the financial support from the National Natural Science Foundation of China (Grant Nos. 12125404, 11974162, and 11834006)the Fundamental Research Funds for the Central Universities。
文摘Helium is the second most abundant element in the universe, and together with silica, they are important components of giant planets. Exploring the reactivity and state of helium and silica under high pressure is crucial for understanding of the evolution and internal structure of giant planets. Here, using first-principles calculations and crystal structure predictions, we identify four stable phases of a helium-silica compound with seven/eight-coordinated silicon atoms at pressure of 600–4000 GPa, corresponding to the interior condition of the outer planets in the solar system. The density of He Si O2 agrees with current structure models of the planets.This helium-silica compound exhibits a superionic-like helium diffusive state under the high-pressure and hightemperature conditions along the isentropes of Saturn, a metallic fluid state in Jupiter, and a solid state in the deep interiors of Uranus and Neptune. These results show that helium may affect the erosion of the rocky core in giant planets and may help to form a diluted core region, which not only highlight the reactivity of helium under high pressure but also provide evidence helpful for building more sophisticated interior models of giant planets.
基金supported by National Natural Science Foundation of China(Grant No.U1710256,U1810115 and 52072256)ShanXi Science and Technology Major Project(Grant No.20181102018,20181102019 and 20201101016)
文摘Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poor electronic conductivity of TMPs,the poor-rate capability,and fast capacity decay greatly hinder its practical application.To address these issues,a low-cost and facile strategy for the synthesis of Ni,N-codoped graphitized carbon(C)and cobalt phosphide(CoP)embedded in carbon fiber(Ni-CoP@CN⊂CF)as self-supporting anode material is demonstrated for the first time.The graphitized carbon and carbon fiber improve the electrical conductivity and inhibit the volume expansion issues.In addition to that,the microporous structure,and ultrasmall sized Ni-CoP offer a high surface area for electrolyte wettability,short Na-ion diffusion path and fast charge transport kinetics.As a result,outstanding electrochemical performance with an average capacity decay of 0.04%cycle^(−1)at 2000 mA g^(−1),an excellent rate capability of 270 mAh g^(−1)@2000 mA g^(−1)and a high energy density of~231.1 Wh kg^(−1)is achieved with binder-free self-supporting anode material.This work shows a potential for designing binder-free and high energy density sodium-ion batteries.
