A novel composite of monoclinic manganite/multi-walled carbon nanotubes(c-MnOOH/MWCNTs)composite as a cathode material of lithium-air batteries was successfully synthesized by a simple one-step hydrothermal method.Owi...A novel composite of monoclinic manganite/multi-walled carbon nanotubes(c-MnOOH/MWCNTs)composite as a cathode material of lithium-air batteries was successfully synthesized by a simple one-step hydrothermal method.Owing to the unique three-dimensional network of c-MnOOH embedded in the porous structure of MWCNTs,the c-MnOOH/MWCNTs composite could have an advantage of high electrocatalytic activities over those of two other kinds of cathode materials(MWCNTs and c-MnOOH/MWCNTs mixture).The results of chargedischarge tests showed that the c-MnOOH/MWCNTs composite as a cathode material of lithium-air batteries could effectively enhance the catalytic activity for the oxygen evolution reduction(OER)process.The lithium-air battery based on c-MnOOH/MWCNTs composite exhibits low charge potential and high discharge capacity.展开更多
In this paper, the macroscopic interaction method and high resolution EXAFS technique with a bent crystal analyzer were combined to study Eu（III） interaction mechanism and microstructure with y-MnOOH as a function o...In this paper, the macroscopic interaction method and high resolution EXAFS technique with a bent crystal analyzer were combined to study Eu（III） interaction mechanism and microstructure with y-MnOOH as a function of pH. The results indicated that Eu（III） interaction with y-MnOOH was apparently dependent on pH but independent of ionic strength, suggesting the for- mation of inner-sphere surface complexation for Eu（III） onto y-MnOOH. Results of EXAFS analysis indicated that Eu was surrounded by -9.00 atoms in first coordination shell at REu-O =2.40A, and second shell of Mn atoms at REu-Mn ≈ 3.60 was observed for the three adsorption samples. These findings suggested formation of a bidentate surface complex with Eu（III） bonding by edge sharing to MnO6-octahedron on y-MnOOH surface. Both the macroscopic interaction data and the molecular level evidence of Eu（III） microstructure at the 3,-MnOOH-water interface should be factored into better understanding the fate and mobility of Eu（III） and related radionuclides in the natural soil and water environment.展开更多
Well-defined Fe3O4/Mn OOH nanoparticles with 61.1 emu·g-1in magnetization intensity and 90.53 m2·g-1in surface area have been synthesized by a new-style of high-frequency impinging stream(HFIS)reactor.In thi...Well-defined Fe3O4/Mn OOH nanoparticles with 61.1 emu·g-1in magnetization intensity and 90.53 m2·g-1in surface area have been synthesized by a new-style of high-frequency impinging stream(HFIS)reactor.In this reactor,two streams first collided together to form nano Fe3O4suspension,which subsequently flew through an S-shaped main channel to generate high-frequency reversing high-gravity fields.At the same time,24 thin liquid sheets impinged into the main channel at the frequencies higher than 100 Hz to create nano Fe3O4/Mn OOH colloids.The obtained powders were characterized by transmission electron microscopy/energy dispersive spectrometer(TEM/EDS),X-ray diffraction(XRD),Brunner–Emmet–Teller(BET)and vibrating sample magnetometer(VSM).Experimental results indicated that low coating ratio prolonged the induction period of heterogeneous nucleation.The high-frequency impingements of 24 thin liquid sheets greatly accelerated the macro-mixing and the initial dispersion.The high-frequency reversing high-gravity fields promoted the mesoand micro-mixing.As a result,nano Fe3O4cores were fleetly and uniformly covered by Mn OOH precursor.As a continuously operated and static high-gravity reactor,the high-frequency impinging stream(HFIS)reactor is being developed to the large-scaled and low-cost production of various nanocomposites.展开更多
We report on the photodetector structures based on perovskite manganite La0.67Ca0.33MnO3 thin films on tilted SrTiO3 (001) substrates. The photovoltaic effect has been observed in response to excitation by 308 nm ultr...We report on the photodetector structures based on perovskite manganite La0.67Ca0.33MnO3 thin films on tilted SrTiO3 (001) substrates. The photovoltaic effect has been observed in response to excitation by 308 nm ultraviolet laser pulse irradiation in duration of 20 ns at room temperature. The outputs ob- tained required no amplification. To reduce the deformation of the signal detected, a series of testing measurements were made to investigate the impedance effect. When the impedance at the oscilloscope end matched to the co-axis cable, the signal trace was almost triangular and symmetrical, with re- sponse time equal to the excitation laser. In addation, the response linearly depends on the irradiated area for low on-sample energy. The devices work well under unbiased conditions and so are simple to configure for practical applications.展开更多
In the present paper, we study the zero-temperature phase diagram of the doped perovskite manganitesat filling x = 0.5 by the real-space Hartree-Fock approximation method. Our purpose is to resolve a controversialissu...In the present paper, we study the zero-temperature phase diagram of the doped perovskite manganitesat filling x = 0.5 by the real-space Hartree-Fock approximation method. Our purpose is to resolve a controversialissue arising recently on the origin of the charge ordered phases in these systems. We find that the antiferromagneticsuperexchange interaction between the localized spins plays the central role in producing the concerned phases. Ourresults confirm some speculations on this issue.展开更多
Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular intere...Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular interest to investigate photon-induced emerging phenomena in spatially confined strongly correlated systems,which are important for applications of these materials in future electronic devices.Colossal magnetoresistive manganites materials offer an ideal platform for such study due to their sensitivity to photo-excitation.Here,we fabricated 900 nm wide La_(0.325)Pr_(0.3)Ca_(0.375)Mn O_3strips,whose width is comparable to the size of the electronic phase separation(EPS)domains in this system.We observed the photoinduced critical fluctuations in the strips,where abrupt resistivity jumps occurred upon photoinduced phase transition depending sensitively on the light intensity.Based on the microscopic views of the EPS domains under photoexcitation,we conclude that such photo-induced resistivity fluctuations originate from the photoinduced phase fluctuations of individual EPS domains when their size becomes comparable to the strip width.展开更多
基金supported by the National High Technology Research and Development Program of China(2011AA11A255)
文摘A novel composite of monoclinic manganite/multi-walled carbon nanotubes(c-MnOOH/MWCNTs)composite as a cathode material of lithium-air batteries was successfully synthesized by a simple one-step hydrothermal method.Owing to the unique three-dimensional network of c-MnOOH embedded in the porous structure of MWCNTs,the c-MnOOH/MWCNTs composite could have an advantage of high electrocatalytic activities over those of two other kinds of cathode materials(MWCNTs and c-MnOOH/MWCNTs mixture).The results of chargedischarge tests showed that the c-MnOOH/MWCNTs composite as a cathode material of lithium-air batteries could effectively enhance the catalytic activity for the oxygen evolution reduction(OER)process.The lithium-air battery based on c-MnOOH/MWCNTs composite exhibits low charge potential and high discharge capacity.
基金Financial supports from the National Natural Science Foundation of China(1117524421207092)+1 种基金the project of Chinese Academy of Sciences(KJCX2-YW-N43)973 projects(2011CB933700)are acknowledged
文摘In this paper, the macroscopic interaction method and high resolution EXAFS technique with a bent crystal analyzer were combined to study Eu（III） interaction mechanism and microstructure with y-MnOOH as a function of pH. The results indicated that Eu（III） interaction with y-MnOOH was apparently dependent on pH but independent of ionic strength, suggesting the for- mation of inner-sphere surface complexation for Eu（III） onto y-MnOOH. Results of EXAFS analysis indicated that Eu was surrounded by -9.00 atoms in first coordination shell at REu-O =2.40A, and second shell of Mn atoms at REu-Mn ≈ 3.60 was observed for the three adsorption samples. These findings suggested formation of a bidentate surface complex with Eu（III） bonding by edge sharing to MnO6-octahedron on y-MnOOH surface. Both the macroscopic interaction data and the molecular level evidence of Eu（III） microstructure at the 3,-MnOOH-water interface should be factored into better understanding the fate and mobility of Eu（III） and related radionuclides in the natural soil and water environment.
基金Supported by the National Key Technology R&D Program of China(2009BAB47B08)the Key Science and Technology Project of Zhejiang Province(2008C03006)+1 种基金the Education Office Project of Zhejiang Province(Y201225412)the Technical Innovation League Project of Zhejiang Province for Seawater Desalination(2011LM301)
文摘Well-defined Fe3O4/Mn OOH nanoparticles with 61.1 emu·g-1in magnetization intensity and 90.53 m2·g-1in surface area have been synthesized by a new-style of high-frequency impinging stream(HFIS)reactor.In this reactor,two streams first collided together to form nano Fe3O4suspension,which subsequently flew through an S-shaped main channel to generate high-frequency reversing high-gravity fields.At the same time,24 thin liquid sheets impinged into the main channel at the frequencies higher than 100 Hz to create nano Fe3O4/Mn OOH colloids.The obtained powders were characterized by transmission electron microscopy/energy dispersive spectrometer(TEM/EDS),X-ray diffraction(XRD),Brunner–Emmet–Teller(BET)and vibrating sample magnetometer(VSM).Experimental results indicated that low coating ratio prolonged the induction period of heterogeneous nucleation.The high-frequency impingements of 24 thin liquid sheets greatly accelerated the macro-mixing and the initial dispersion.The high-frequency reversing high-gravity fields promoted the mesoand micro-mixing.As a result,nano Fe3O4cores were fleetly and uniformly covered by Mn OOH precursor.As a continuously operated and static high-gravity reactor,the high-frequency impinging stream(HFIS)reactor is being developed to the large-scaled and low-cost production of various nanocomposites.
基金the National Natural Science Foundation of China (Grant Nos. 50672132, 60576015 and 60778034)the Key Project of the Ministry of Educa-tion of China (Grant No. 107020)
文摘We report on the photodetector structures based on perovskite manganite La0.67Ca0.33MnO3 thin films on tilted SrTiO3 (001) substrates. The photovoltaic effect has been observed in response to excitation by 308 nm ultraviolet laser pulse irradiation in duration of 20 ns at room temperature. The outputs ob- tained required no amplification. To reduce the deformation of the signal detected, a series of testing measurements were made to investigate the impedance effect. When the impedance at the oscilloscope end matched to the co-axis cable, the signal trace was almost triangular and symmetrical, with re- sponse time equal to the excitation laser. In addation, the response linearly depends on the irradiated area for low on-sample energy. The devices work well under unbiased conditions and so are simple to configure for practical applications.
文摘In the present paper, we study the zero-temperature phase diagram of the doped perovskite manganitesat filling x = 0.5 by the real-space Hartree-Fock approximation method. Our purpose is to resolve a controversialissue arising recently on the origin of the charge ordered phases in these systems. We find that the antiferromagneticsuperexchange interaction between the localized spins plays the central role in producing the concerned phases. Ourresults confirm some speculations on this issue.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0300702)the National Basic Research Program of China(973 Program)(Grant No.2014CB921104)+1 种基金the Program of Shanghai Academic Research Leader(Grant No.17XD1400400)the National Natural Science Foundation of China(Grant No.11504053)
文摘Light,acting as an external stimulus to induce various intriguing phenomena ranging from photovoltaics to photoinduced catalysis,exerts prominent effects in strongly correlated systems.It would be of particular interest to investigate photon-induced emerging phenomena in spatially confined strongly correlated systems,which are important for applications of these materials in future electronic devices.Colossal magnetoresistive manganites materials offer an ideal platform for such study due to their sensitivity to photo-excitation.Here,we fabricated 900 nm wide La_(0.325)Pr_(0.3)Ca_(0.375)Mn O_3strips,whose width is comparable to the size of the electronic phase separation(EPS)domains in this system.We observed the photoinduced critical fluctuations in the strips,where abrupt resistivity jumps occurred upon photoinduced phase transition depending sensitively on the light intensity.Based on the microscopic views of the EPS domains under photoexcitation,we conclude that such photo-induced resistivity fluctuations originate from the photoinduced phase fluctuations of individual EPS domains when their size becomes comparable to the strip width.
