由于高安全、高功率和超长循环寿命等优点,钛酸锂负极材料近年来得到了广泛关注,基于钛酸锂负极的高性能超级电池电容器和锂离子电池也成为近年来的研究热点.本文采用化学氧化法制备了有机物正极材料聚三苯胺,并通过经典的电化学测试方...由于高安全、高功率和超长循环寿命等优点,钛酸锂负极材料近年来得到了广泛关注,基于钛酸锂负极的高性能超级电池电容器和锂离子电池也成为近年来的研究热点.本文采用化学氧化法制备了有机物正极材料聚三苯胺,并通过经典的电化学测试方法研究了其储能机理及相应的电极动力学过程.研究结果表明,该有机物正极的储能机制主要是基于阴离子的吸脱附反应,并表现出85 m A·g-1的可逆容量,且其动力学过程不受扩散控制,属于典型的赝电容行为.将该正极与钛酸锂负极结合构成了新型的电池电容体系,并对其电化学性能进行了研究,结果表明该体系具有高功率特性,且能量密度高于传统的混合型超级电容器.此外,本文还对该有机物正极的不足和实际应用中所面临的挑战做了初步分析.展开更多
The(Ca,R)FeAs_(2)(R=La,Pr,etc.)superconductors with a signature of superconductivity transition above 40 K possess a new kind of block layers that consist of zig-zag As chains.We report the electronic structure of the...The(Ca,R)FeAs_(2)(R=La,Pr,etc.)superconductors with a signature of superconductivity transition above 40 K possess a new kind of block layers that consist of zig-zag As chains.We report the electronic structure of the new(Ca,La)FeAs_(2)superconductor investigated by both band structure calculations and high resolution angle-resolved photoemission spectroscopy measurements.Band structure calculations indicate that there are four hole-like bands around the zone centerΓ(0,0)and two electron-like bands near the zone corner M(π,π)in CaFeAs_(2).In our angle-resolved photoemission measurements on(Ca0.9La0.1)FeAs_(2),we have observed three hole-like bands around theΓpoint and one electron-like Fermi surface near the M(π,π)point.These results provide important information to compare and contrast with the electronic structure of other iron-based compounds in understanding the superconductivity mechanism in the iron-based superconductors.展开更多
High resolution angle-resolved photoemission measurements are carried out to systematically investigate the effect of cleaving temperature on the electronic structures and Fermi surfaces of Sr2RuO4.Unlike previous rep...High resolution angle-resolved photoemission measurements are carried out to systematically investigate the effect of cleaving temperature on the electronic structures and Fermi surfaces of Sr2RuO4.Unlike previous reports,which found that a high cleaving temperature can suppress the surface Fermi surface,we find that the surface Fermi surface remains obvious and strong in Sr2RuO4 cleaved at high temperature,even at room temperature.This indicates that cleaving temperature is not a key effective factor in suppressing surface bands.On the other hand,the bulk bands can be enhanced in an aged surface of Sr2RuO4 that has been cleaved and held for a long time.We have also carried out laser ARPES measurements on Sr_(2)RuO_(4) by using a vacuum ultra-violet laser (photon energy at 6.994eV) and found an obvious enhancement of bulk bands even for samples cleaved at low temperature.This information is important for realizing an effective approach to manipulating and detecting the surface and bulk electronic structure of Sr2RuO4.In particular,the enhancement of bulk sensitivity,along with the super-high instrumental resolution of VUV laser ARPES,will be advantageous in investigating fine electronic structure and superconducting properties of Sr_(2)RuO_(4) in the future.展开更多
High-quality large single crystals of Ni-and Zn-doped Bi_(2)Sr_(2)Ca(Cu_(2−x)M_(x))O_(8+δ)(M=Ni or Zn)have been successfully grown by the traveling solvent floating zone technique.The single crystals are characterize...High-quality large single crystals of Ni-and Zn-doped Bi_(2)Sr_(2)Ca(Cu_(2−x)M_(x))O_(8+δ)(M=Ni or Zn)have been successfully grown by the traveling solvent floating zone technique.The single crystals are characterized by compositional and structural analyses and their physical properties are investigated by magnetic susceptibility and resistivity measurements.A record high critical temperature with a T_(c)=97.5 K has been achieved in the annealed pristine Bi2212 single crystal.Substitution of Cu by Ni or Zn reduces the superconducting transition temperature when compared with pristine Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)grown under similar conditions.The successful growth of such pristine Ni-and Zn-doped Bi2212 single crystals will facilitate studies of the relationship between the magnetism and superconductivity in high-temperature cuprate superconductors.展开更多
文摘由于高安全、高功率和超长循环寿命等优点,钛酸锂负极材料近年来得到了广泛关注,基于钛酸锂负极的高性能超级电池电容器和锂离子电池也成为近年来的研究热点.本文采用化学氧化法制备了有机物正极材料聚三苯胺,并通过经典的电化学测试方法研究了其储能机理及相应的电极动力学过程.研究结果表明,该有机物正极的储能机制主要是基于阴离子的吸脱附反应,并表现出85 m A·g-1的可逆容量,且其动力学过程不受扩散控制,属于典型的赝电容行为.将该正极与钛酸锂负极结合构成了新型的电池电容体系,并对其电化学性能进行了研究,结果表明该体系具有高功率特性,且能量密度高于传统的混合型超级电容器.此外,本文还对该有机物正极的不足和实际应用中所面临的挑战做了初步分析.
基金Supported by the National Natural Science Foundation of China under Grant No 10734120the National Basic Research Program of China under Grant Nos 2011CB921703 and 2011CB605903.
文摘The(Ca,R)FeAs_(2)(R=La,Pr,etc.)superconductors with a signature of superconductivity transition above 40 K possess a new kind of block layers that consist of zig-zag As chains.We report the electronic structure of the new(Ca,La)FeAs_(2)superconductor investigated by both band structure calculations and high resolution angle-resolved photoemission spectroscopy measurements.Band structure calculations indicate that there are four hole-like bands around the zone centerΓ(0,0)and two electron-like bands near the zone corner M(π,π)in CaFeAs_(2).In our angle-resolved photoemission measurements on(Ca0.9La0.1)FeAs_(2),we have observed three hole-like bands around theΓpoint and one electron-like Fermi surface near the M(π,π)point.These results provide important information to compare and contrast with the electronic structure of other iron-based compounds in understanding the superconductivity mechanism in the iron-based superconductors.
基金Support by the National Natural Science Foundation of China under Grant Nos 10734120 and 91021006the National Basic Research Program of China under Grant Nos 2011CB921703 and 2011CB605903.
文摘High resolution angle-resolved photoemission measurements are carried out to systematically investigate the effect of cleaving temperature on the electronic structures and Fermi surfaces of Sr2RuO4.Unlike previous reports,which found that a high cleaving temperature can suppress the surface Fermi surface,we find that the surface Fermi surface remains obvious and strong in Sr2RuO4 cleaved at high temperature,even at room temperature.This indicates that cleaving temperature is not a key effective factor in suppressing surface bands.On the other hand,the bulk bands can be enhanced in an aged surface of Sr2RuO4 that has been cleaved and held for a long time.We have also carried out laser ARPES measurements on Sr_(2)RuO_(4) by using a vacuum ultra-violet laser (photon energy at 6.994eV) and found an obvious enhancement of bulk bands even for samples cleaved at low temperature.This information is important for realizing an effective approach to manipulating and detecting the surface and bulk electronic structure of Sr2RuO4.In particular,the enhancement of bulk sensitivity,along with the super-high instrumental resolution of VUV laser ARPES,will be advantageous in investigating fine electronic structure and superconducting properties of Sr_(2)RuO_(4) in the future.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11190022 and 10734120the National Basic Research Program of China under Grant No 2011CB921703.
文摘High-quality large single crystals of Ni-and Zn-doped Bi_(2)Sr_(2)Ca(Cu_(2−x)M_(x))O_(8+δ)(M=Ni or Zn)have been successfully grown by the traveling solvent floating zone technique.The single crystals are characterized by compositional and structural analyses and their physical properties are investigated by magnetic susceptibility and resistivity measurements.A record high critical temperature with a T_(c)=97.5 K has been achieved in the annealed pristine Bi2212 single crystal.Substitution of Cu by Ni or Zn reduces the superconducting transition temperature when compared with pristine Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)grown under similar conditions.The successful growth of such pristine Ni-and Zn-doped Bi2212 single crystals will facilitate studies of the relationship between the magnetism and superconductivity in high-temperature cuprate superconductors.
