Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductiv...Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly（ether ether ketone） （SPEEK）. By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic（MD） simulations and transmission electron microscope （TEM） observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.展开更多
The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with ...The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with the sputtering time increasing. The as-sputtered films are super saturation solid solution of Cu-Fe. After annealing at 500℃, α-Fe particle can be segregated from the Cu matrix. The orientations α-Fe particles in the annealed film without magnetic field are random. But the clear texture of α-Fe particles in the annealed film with magnetic field is formed, and the 〈001〉 direction of α-Fe particles tends to be parallel to the magnetic field direction.展开更多
Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was s...Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was systematically investigated. Linear current-voltage characteristics were observed in the as-prepared and the 10 h annealed samples, and nonlinear current-voltage characteristics was found in the 100 h annealed sample. At the same time, segregation of impurity phase and micro-cracks were found on the surfaces of the 100 h annealed samples, which was testified to be Ba ion impurity. Analysis showed that the changes of electronic properties were caused by barium ion im-purities and micro-cracks in the 100 h annealed sample.展开更多
Development of advanced display and lighting technology such as field emission displays and plasma display panels requires phosphor which has a high efficiency and low degradation. Particle sizes and the locations of ...Development of advanced display and lighting technology such as field emission displays and plasma display panels requires phosphor which has a high efficiency and low degradation. Particle sizes and the locations of dopants in the hosts take an important role in the luminescence emissions of phosphors. ZnO nanoparticles are widely employed in plasma field emission display devices and well investigated;however, lanthanide (Ln3+) doped ZnO needs more investigations. In ZnO:Eu the lanthanide ions (Eu3+) may occupy either Zn2+ lattice site or on surface of ZnO crystal. The emissions of Eu3+ ion on the surface are the characteristic of Eu2 O3 , which leads to weak luminescence emission. To observe such phenomena, nanoparticles of ZnO, 2 at.% Eu3+ doped ZnO (ZnO:Eu) and ZnO:Eu covered with yattria matrix were prepared by wet chemical method at low temperature. The prepared nanoparticles were characterized by XRD and TEM. XRD data reveal the significant phase segregation of the annealed nanoparticles compared with lower heated samples. This phase segregation of Eu3+ ion establishes responsible for the decrease luminescence intensity of annealed ZnO:Eu nanoparticles compared with the as-prepared ZnO:Eu nanoparticles. Improvement on luminescence emissions could be achieved only for the as-prepared ZnO:Eu nanoparticles while covered with yattria matrix.展开更多
The effect of doping additional Bi on the magnetoresistance （MR） of La2/3Ca1/3BxMn1-x O3 was investigated. It is found that traditional colossal magnetoresistance （CMR） peak can only be observed in the x〈0.05 sam...The effect of doping additional Bi on the magnetoresistance （MR） of La2/3Ca1/3BxMn1-x O3 was investigated. It is found that traditional colossal magnetoresistance （CMR） peak can only be observed in the x〈0.05 samples and the peak value decreases with the increase of x, but the x≥0.05 samples show a magnetoresistance plateau above 200 K because of the presence of additional （La,Ca,Bi）-O layers. Moreover, this MR plateau is enhanced for the segregation of the La, Ca, and Bi elements.展开更多
基金financially supported by the National Key Research and Development Program of China (2016YFB0101203)the National Natural Science Foundation of China (91545205,21633008)
文摘Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly（ether ether ketone） （SPEEK）. By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic（MD） simulations and transmission electron microscope （TEM） observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.
文摘The segregation behavior of α-Fe particles in Cu-Fe film prepared by magnetron sputtering was studied by X-ray scattering and X-ray diffraction. The results show that the roughness of the film surface increases with the sputtering time increasing. The as-sputtered films are super saturation solid solution of Cu-Fe. After annealing at 500℃, α-Fe particle can be segregated from the Cu matrix. The orientations α-Fe particles in the annealed film without magnetic field are random. But the clear texture of α-Fe particles in the annealed film with magnetic field is formed, and the 〈001〉 direction of α-Fe particles tends to be parallel to the magnetic field direction.
基金supported by the National Natural Science Foundation of China (10975103)
文摘Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was systematically investigated. Linear current-voltage characteristics were observed in the as-prepared and the 10 h annealed samples, and nonlinear current-voltage characteristics was found in the 100 h annealed sample. At the same time, segregation of impurity phase and micro-cracks were found on the surfaces of the 100 h annealed samples, which was testified to be Ba ion impurity. Analysis showed that the changes of electronic properties were caused by barium ion im-purities and micro-cracks in the 100 h annealed sample.
文摘Development of advanced display and lighting technology such as field emission displays and plasma display panels requires phosphor which has a high efficiency and low degradation. Particle sizes and the locations of dopants in the hosts take an important role in the luminescence emissions of phosphors. ZnO nanoparticles are widely employed in plasma field emission display devices and well investigated;however, lanthanide (Ln3+) doped ZnO needs more investigations. In ZnO:Eu the lanthanide ions (Eu3+) may occupy either Zn2+ lattice site or on surface of ZnO crystal. The emissions of Eu3+ ion on the surface are the characteristic of Eu2 O3 , which leads to weak luminescence emission. To observe such phenomena, nanoparticles of ZnO, 2 at.% Eu3+ doped ZnO (ZnO:Eu) and ZnO:Eu covered with yattria matrix were prepared by wet chemical method at low temperature. The prepared nanoparticles were characterized by XRD and TEM. XRD data reveal the significant phase segregation of the annealed nanoparticles compared with lower heated samples. This phase segregation of Eu3+ ion establishes responsible for the decrease luminescence intensity of annealed ZnO:Eu nanoparticles compared with the as-prepared ZnO:Eu nanoparticles. Improvement on luminescence emissions could be achieved only for the as-prepared ZnO:Eu nanoparticles while covered with yattria matrix.
基金Funded by the Foundation for the Author of National Excellent Doctoral Dissertation of China (FANEDD) (No. 200233)
文摘The effect of doping additional Bi on the magnetoresistance （MR） of La2/3Ca1/3BxMn1-x O3 was investigated. It is found that traditional colossal magnetoresistance （CMR） peak can only be observed in the x〈0.05 samples and the peak value decreases with the increase of x, but the x≥0.05 samples show a magnetoresistance plateau above 200 K because of the presence of additional （La,Ca,Bi）-O layers. Moreover, this MR plateau is enhanced for the segregation of the La, Ca, and Bi elements.
