The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We h...The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We here demonstrate exfoliations and nano-fabrications of Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips,which possess a rather weak pinning volume of vortices,relatively low resistivity,and large normal electron diffusion coefficient.The deduced vortex velocity in Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips can be up to 300 km/s near the superconducting transition temperature,well above the speed of sound.The observed vortex velocity is an order of magnitude faster than that of conventional superconducting systems,representing a perfect platform for exploration of ultra-fast vortex matter and a good candidate for fabrications of superconducting nanowire single photon detectors or superconducting THz modulator.展开更多
As a typical hole-doped cuprate superconductor,Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)carrier doping is mostly determined by its oxygen content.Traditional doping methods can regulate its doping level within the range of...As a typical hole-doped cuprate superconductor,Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)carrier doping is mostly determined by its oxygen content.Traditional doping methods can regulate its doping level within the range of hole doping.Here we report the first application of CaH_(2)annealing method in regulating the doping level of Bi2212.By continuously controlling the anneal time,a series of differently doped samples can be obtained.The combined experimental results of x-ray diffraction,scanning transmission electron microscopy,resistance and Hall measurements demonstrate that the CaH_(2)induced topochemical reaction can effectively change the oxygen content of Bi2212 within a very wide range,even switching from hole doping to electron doping.We also found evidence of a low-T_c superconducting phase in the electron doping side.展开更多
Effects of isochronal annealing on the positron annihilation of glassy Bi_(1.6) Pb_(0.4) Sr_(1.9)Ca_2 Cu_(3.1)O_y(BPSCCO)have been reported.It is shown that the crystallization influences obviously the positron annihi...Effects of isochronal annealing on the positron annihilation of glassy Bi_(1.6) Pb_(0.4) Sr_(1.9)Ca_2 Cu_(3.1)O_y(BPSCCO)have been reported.It is shown that the crystallization influences obviously the positron annihilation characteristics of BPSCCO.A maximum is found in the region of crystallization temperature in curves of mean lifetime and peak/wing ratio, one of Doppler Iineshape parameter,with annealing temperature;the bulk lifetime of positron annihilation in the glassy state is longer than that in the crystalline one.Positron annihilation spectroscopy could be used for studying structure of glassy BPSCCO and its change with heat treatment.展开更多
Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread...Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread applications.Herein,we first present the synthesis of 2D lead-free halide perovskite (Cs_(3)Bi_(2)I_(9)) nanosheets with self-template-oriented method,in which BiOI/Bi_(2)O_(2) nanosheets were used as the template and Bi ion source simultaneously.Through facile electrostatic self-assembly strategy,a Z-scheme heterojunction composed of Cs_(3)Bi_(2)I_(9)nanosheets and CeO_(2) nanosheets (Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1) was constructed as photocatalyst for the photo-reduction of CO_(2) coupled with the oxidation of H_(2)O.Due to the matching energy levels and the close interfacial contact between Cs_(3)Bi_(2)I_(9)and CeO_(2) nanosheets,the separation efficiency of the photogenerated carriers in Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1 composite was significantly improved.Consequently,the environment-friendly halide perovskite heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1presents impressive photocatalytic activity for the reduction of CO_(2)to CH_(4)and CO with an electron consumption yield of 877.04μmol g^(-1),which is over 7 and 15 times higher than those of pristine Cs_(3)Bi_(2)I_(9)and CeO_(2)nanosheets,exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO_(2)reduction.展开更多
通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后...通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后复合材料的带隙减小,光生载流子复合率大幅下降,当Bi_(2)S_(3)循环5次时,TiO_(2)纳米复合材料的光电化学性能最好。带隙减小到2.9 e V,光电流密度由改性前的200μA·cm^(-2)提升至550μA·cm^(-2),是改性前的2.75倍;将其与304不锈钢耦合后,电位降至-1.0 V,比改性前的耦合电位低80 m V,可以进一步提升对304不锈钢的光生阴极保护效果。展开更多
The effect of Y substitution for Ca on the crystal structure and electronic states of Bi_2Sr_2CaCu_2O_(8+y) was studied. It is found that the modulation period of the incommensurate superlattice along b axis decreases...The effect of Y substitution for Ca on the crystal structure and electronic states of Bi_2Sr_2CaCu_2O_(8+y) was studied. It is found that the modulation period of the incommensurate superlattice along b axis decreases from 4.7b to about 4.0b gradually, which implies the change of the extra oxygen atoms residing within double Bi-O layers. Two kinds of modulation structures with periods of 4b and 8b exist in the same compound as Ca is completely substituted by Y. XPS was employed to study the change in the electronic structure. The results suggest that the variation of superconductivity is not caused by the slight change in crystal structure, but rather by the hole filling in O2p orbitals in CuO_2 layers. For this substituted system, it is still the case where one hole in Cu3d orbital (3d^9) is corresponding to the strong correlation antiferromaguetic insulator, and an extra hole in O2p orbital in CuO_2 layer (3d^9L) to the superconductor.展开更多
SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<...SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub> resemble each other. The antiferromagnetic phase is commonly situated in the vicinity of the superconductive phase. In Bi-2212 sys-展开更多
The heterojunction effect can effectively improve the separation efficiency of the photocatalyst’s photo-generated electron and hole pairs,thereby greatly improving the photocatalytic hydrogen production performance ...The heterojunction effect can effectively improve the separation efficiency of the photocatalyst’s photo-generated electron and hole pairs,thereby greatly improving the photocatalytic hydrogen production performance of the photocatalyst.In this paper,Bi_(6)O_(6)(OH)_(3)(NO_(3))_(3)·1.5H_(2)O(BBN)and ZnO are used to construct and synthesize Bi_(6)O_(6)(OH)_(3)(NO_(3))_(3)·1.5H_(2)O/ZnO(BBN/ZnO)heterojunction photocatalyst.Under UV-vis light irradiation,the BBN/ZnO composite could generate H_(2)with a rate of 28.66μmol·g^(−1)·h^(−1),which is higher than pure BBN(0.92μmol·g^(−1)·h^(−1))and ZnO(6.54μmol·h^(−1)·g^(−1))at around 31.1 and 4.4 times,respectively.Moreover,the experimental results found that the composite still exhibits excellent photocatalytic activity and maintains a high and stable activity in the 12-hour experiment with 3 cycles.The possible mechanism to enhance the photocatalytic behavior is attributed to the expanded light absorption range,reduced surface migration resistance,and inhibited recombination of photo-generated electron and hole pairs.展开更多
Simultaneous equilibrium was applied to the thermodynamic analysis and calculation of Bi（Ⅲ）-X（Cl-, NO-3）-H2O systems, based on which the diagrams of the logarithm of equilibrium concentration of Bi（Ⅲ） of serie...Simultaneous equilibrium was applied to the thermodynamic analysis and calculation of Bi（Ⅲ）-X（Cl-, NO-3）-H2O systems, based on which the diagrams of the logarithm of equilibrium concentration of Bi（Ⅲ） of series precipitation vs pH value of these two systems at 25 ℃ were obtained, and the pH ranges of the stable zones of various precipitations were analyzed and determined. In Bi（Ⅲ）-Cl--H2O system, the variations of c0(Bi3+) and （c0（Cl-）） have little effect on the equilibria of Bi（OH）3-solution and BiOOH-solution, but has great influence on the （equilibrium） of BiOCl-solution. However, in Bi（Ⅲ）-NO-3-H2O system, the variations of c0(Bi3+) and c0（NO-3） have little effect on equilibria of Bi（OH）3-solution, BiOOH-solution and Bi2O3-solution. When pH value is high, Bi2O3 is the thermodynamic stable phase, its stable zone is the widest, almost including the stable zones of BiOCl or （BiONO3,） （Bi（OH）3） and BiOOH. Bi（OH）3 cannot be obtained from Bi（Ⅲ）-Cl--H2O system, even strong alkaline media. Bi2O3 can be obtained from the solution directly, and highly pure BiOCl or BiONO3 can also be obtained through strictly controlling pH value.展开更多
基金supporting high quality of post growth treatment Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ)single crystalssupported by the National Key Research and Development Program of China(Grant No.2017YFA0304000)+4 种基金the National Natural Science Foundation of China(Grant Nos.61971408 and 61827823)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Shanghai Rising-Star Program(Grant No.20QA1410900)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant Nos.2020241 and 2021230)the Natural Science Foundation of Shanghai(Grant No.19ZR1467400)。
文摘The maximum velocity of a mobile vortex in movement is generally limited by the phenomenon of flux-flow instability(FFI),which necessitates weak vortex pinning and fast heat removal from non-equilibrium electrons.We here demonstrate exfoliations and nano-fabrications of Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips,which possess a rather weak pinning volume of vortices,relatively low resistivity,and large normal electron diffusion coefficient.The deduced vortex velocity in Bi_(2)Sr_(2)Ca_(2)Cu_(3)O_(10+δ) crystalline nanostrips can be up to 300 km/s near the superconducting transition temperature,well above the speed of sound.The observed vortex velocity is an order of magnitude faster than that of conventional superconducting systems,representing a perfect platform for exploration of ultra-fast vortex matter and a good candidate for fabrications of superconducting nanowire single photon detectors or superconducting THz modulator.
基金supported by the National Natural Science Foundation of China(Grant Nos.11888101 and U1832202)the Chinese Academy of Sciences(Grant Nos.QYZDB-SSWSLH043 and XDB33000000)+4 种基金the K.C.Wong Education Foundation(Grant No.GJTD-2018-01)the Informatization Plan of Chinese Academy of Sciences(Grant No.CAS-WX2021SF-0102)supported by the Synergetic Extreme Condition User Facility(SECUF)supported by China Postdoctoral Science Foundation(Grant Nos.2020M680726 and YJ20200325)supported by US DOE(Grant Nos.DE-SC0010526 and DE-SC0012704)。
文摘As a typical hole-doped cuprate superconductor,Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)carrier doping is mostly determined by its oxygen content.Traditional doping methods can regulate its doping level within the range of hole doping.Here we report the first application of CaH_(2)annealing method in regulating the doping level of Bi2212.By continuously controlling the anneal time,a series of differently doped samples can be obtained.The combined experimental results of x-ray diffraction,scanning transmission electron microscopy,resistance and Hall measurements demonstrate that the CaH_(2)induced topochemical reaction can effectively change the oxygen content of Bi2212 within a very wide range,even switching from hole doping to electron doping.We also found evidence of a low-T_c superconducting phase in the electron doping side.
文摘Effects of isochronal annealing on the positron annihilation of glassy Bi_(1.6) Pb_(0.4) Sr_(1.9)Ca_2 Cu_(3.1)O_y(BPSCCO)have been reported.It is shown that the crystallization influences obviously the positron annihilation characteristics of BPSCCO.A maximum is found in the region of crystallization temperature in curves of mean lifetime and peak/wing ratio, one of Doppler Iineshape parameter,with annealing temperature;the bulk lifetime of positron annihilation in the glassy state is longer than that in the crystalline one.Positron annihilation spectroscopy could be used for studying structure of glassy BPSCCO and its change with heat treatment.
基金financially supported by the Natural Science Foundation of Tianjin City (17JCJQJC43800, 19JCQNJC05500)the National Key R&D Program of China (2017YFA0700104)+1 种基金NSFC (21931007)the 111 Project of China (D17003)。
文摘Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial photosynthesis in recent years.However,the toxicity of lead in LHP seriously limits their potential for widespread applications.Herein,we first present the synthesis of 2D lead-free halide perovskite (Cs_(3)Bi_(2)I_(9)) nanosheets with self-template-oriented method,in which BiOI/Bi_(2)O_(2) nanosheets were used as the template and Bi ion source simultaneously.Through facile electrostatic self-assembly strategy,a Z-scheme heterojunction composed of Cs_(3)Bi_(2)I_(9)nanosheets and CeO_(2) nanosheets (Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1) was constructed as photocatalyst for the photo-reduction of CO_(2) coupled with the oxidation of H_(2)O.Due to the matching energy levels and the close interfacial contact between Cs_(3)Bi_(2)I_(9)and CeO_(2) nanosheets,the separation efficiency of the photogenerated carriers in Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1 composite was significantly improved.Consequently,the environment-friendly halide perovskite heterojunction Cs_(3)Bi_(2)I_(9)/CeO_(2)-3:1presents impressive photocatalytic activity for the reduction of CO_(2)to CH_(4)and CO with an electron consumption yield of 877.04μmol g^(-1),which is over 7 and 15 times higher than those of pristine Cs_(3)Bi_(2)I_(9)and CeO_(2)nanosheets,exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO_(2)reduction.
文摘通过连续离子层吸附法(SILAR)在TiO_(2)纳米管上负载Bi_(2)S_(3),通过XRD、SEM、XPS等手段对Bi_(2)S_(3)/TiO_(2)纳米复合材料的形貌、结构、元素组成和价态进行表征。同时在模拟太阳光条件下进行光电化学性能测试。Bi_(2)S_(3)改性后复合材料的带隙减小,光生载流子复合率大幅下降,当Bi_(2)S_(3)循环5次时,TiO_(2)纳米复合材料的光电化学性能最好。带隙减小到2.9 e V,光电流密度由改性前的200μA·cm^(-2)提升至550μA·cm^(-2),是改性前的2.75倍;将其与304不锈钢耦合后,电位降至-1.0 V,比改性前的耦合电位低80 m V,可以进一步提升对304不锈钢的光生阴极保护效果。
基金Project supported by the National Natural Science Foundation of China and by the Laboratory of Structure and Element Analysis, Academia Sinica
文摘The effect of Y substitution for Ca on the crystal structure and electronic states of Bi_2Sr_2CaCu_2O_(8+y) was studied. It is found that the modulation period of the incommensurate superlattice along b axis decreases from 4.7b to about 4.0b gradually, which implies the change of the extra oxygen atoms residing within double Bi-O layers. Two kinds of modulation structures with periods of 4b and 8b exist in the same compound as Ca is completely substituted by Y. XPS was employed to study the change in the electronic structure. The results suggest that the variation of superconductivity is not caused by the slight change in crystal structure, but rather by the hole filling in O2p orbitals in CuO_2 layers. For this substituted system, it is still the case where one hole in Cu3d orbital (3d^9) is corresponding to the strong correlation antiferromaguetic insulator, and an extra hole in O2p orbital in CuO_2 layer (3d^9L) to the superconductor.
文摘SINCE the discovery of high-T<sub>c</sub> superconductors, experiments have revealed that the phase diagrams of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+x</sub> resemble each other. The antiferromagnetic phase is commonly situated in the vicinity of the superconductive phase. In Bi-2212 sys-
基金This work was supported by the Natural Science Foundation of Fujian Province[2020J01833]the Fujian Engineering Research Center of New Chinese lacquer Material[No.323030030702]+3 种基金the humbly acknowledge international funding provided by Fujian Agriculture and Forestry University[No.KXB16001A]the Education Research Program for Young and Middle-aged Teachers of Fujian Education Department[No.JAT190132]the open fund of the Key Laboratory of National Forestry&Grassland Bureau for Plant Fiber Functional Materials,Fujian Agriculture and Forestry University[No.2019KFJJ15]Key Laboratory of New Functional Textile Fiber and Material of Fujian Province will open fund project in 2020[MJUKF-FMSM202005,FKLTF 1708].
文摘The heterojunction effect can effectively improve the separation efficiency of the photocatalyst’s photo-generated electron and hole pairs,thereby greatly improving the photocatalytic hydrogen production performance of the photocatalyst.In this paper,Bi_(6)O_(6)(OH)_(3)(NO_(3))_(3)·1.5H_(2)O(BBN)and ZnO are used to construct and synthesize Bi_(6)O_(6)(OH)_(3)(NO_(3))_(3)·1.5H_(2)O/ZnO(BBN/ZnO)heterojunction photocatalyst.Under UV-vis light irradiation,the BBN/ZnO composite could generate H_(2)with a rate of 28.66μmol·g^(−1)·h^(−1),which is higher than pure BBN(0.92μmol·g^(−1)·h^(−1))and ZnO(6.54μmol·h^(−1)·g^(−1))at around 31.1 and 4.4 times,respectively.Moreover,the experimental results found that the composite still exhibits excellent photocatalytic activity and maintains a high and stable activity in the 12-hour experiment with 3 cycles.The possible mechanism to enhance the photocatalytic behavior is attributed to the expanded light absorption range,reduced surface migration resistance,and inhibited recombination of photo-generated electron and hole pairs.
文摘Simultaneous equilibrium was applied to the thermodynamic analysis and calculation of Bi（Ⅲ）-X（Cl-, NO-3）-H2O systems, based on which the diagrams of the logarithm of equilibrium concentration of Bi（Ⅲ） of series precipitation vs pH value of these two systems at 25 ℃ were obtained, and the pH ranges of the stable zones of various precipitations were analyzed and determined. In Bi（Ⅲ）-Cl--H2O system, the variations of c0(Bi3+) and （c0（Cl-）） have little effect on the equilibria of Bi（OH）3-solution and BiOOH-solution, but has great influence on the （equilibrium） of BiOCl-solution. However, in Bi（Ⅲ）-NO-3-H2O system, the variations of c0(Bi3+) and c0（NO-3） have little effect on equilibria of Bi（OH）3-solution, BiOOH-solution and Bi2O3-solution. When pH value is high, Bi2O3 is the thermodynamic stable phase, its stable zone is the widest, almost including the stable zones of BiOCl or （BiONO3,） （Bi（OH）3） and BiOOH. Bi（OH）3 cannot be obtained from Bi（Ⅲ）-Cl--H2O system, even strong alkaline media. Bi2O3 can be obtained from the solution directly, and highly pure BiOCl or BiONO3 can also be obtained through strictly controlling pH value.
