Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice...Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.展开更多
Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity ...Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）, cyclic voltammetry（CV）, linear sweep voltammetry（LSV）, and chronoamperometry（CA）. There were mainly three types of pore size within the hierarchical porous carbon： 2 μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon（HPC） as positive electrode was obviously larger than that using carbon felt; the former was 665.5 mAh with a coulombic efficiency of 89.0% and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5% and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles.These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.展开更多
The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main resul...The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main results obtained can be summarized as follows: The cerium carbide CeC2 can be precipitated in cast steel and distributed along the grain boundaries. Heat treating the steel as austenite, the CeC2 transformed into ternary compound Fe4Ce4 C7, its thermodynamics of formation in steel being expressed as: ac exp(6400/T-6. 28), where 1015K<T<1523K and ac 0.126. Fe4Ce4C7 in steel is primitive tetragonal, anisotmpic in polarized light, opaque in dark field and a little greyer than iron matrix in bright field. Its Vickers hardness is about 420kg/mm2 (annealed) and 750kg/mm2 (quenched). This phase in steel is stable in basic and organic solutions and can be seperated from the matrix by electrolysis. Moreover, the LaC2 in steel can not be transformed into Fe-La-C ternary compound in present investigation.展开更多
Polycrystalline Ce_(0.95)Ca_(0.05)F_(2.95) was prepared by a conventional solid-state reaction. The heat stability and ion conductivity of Ce_(0.95)Ca_(0.05)F_(2.95) were investigated by a high temperature calorimeter...Polycrystalline Ce_(0.95)Ca_(0.05)F_(2.95) was prepared by a conventional solid-state reaction. The heat stability and ion conductivity of Ce_(0.95)Ca_(0.05)F_(2.95) were investigated by a high temperature calorimeter and an ac impedance technique. Experimental results indicate that Ce_(0.95)Ca_(0.05)F_(2.95) is stable at temperatures below 1000 K and represents the ionic conductivity of 1×10^(-3) to 10^(-1) Ω^(-1)·cm^(-1) in temperature range of 660 to 1180 K.展开更多
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY12A01002)the National Natural Science Foundation of China(Grant Nos.11204058 and 21073162)the Hangzhou Dianzi University,China(Grant No.KYF09150603)
文摘Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.
基金supported by National Program on Key Basic Research Project of China(973 Program,2012CB215500)National Natural Science Foundation of China(21361010)
文摘Advanced zinc-cerium redox flow battery（ZCRFB） is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray photoelectron spectroscopy（XPS）, cyclic voltammetry（CV）, linear sweep voltammetry（LSV）, and chronoamperometry（CA）. There were mainly three types of pore size within the hierarchical porous carbon： 2 μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon（HPC） as positive electrode was obviously larger than that using carbon felt; the former was 665.5 mAh with a coulombic efficiency of 89.0% and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5% and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles.These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.
文摘The thermodynamics and the properties of the cerium carbide Fe4 Ce4 C7 in steel have been studied by means of metallography, electron microprobe, X-ray diffraction technique and electrolytic separation. The main results obtained can be summarized as follows: The cerium carbide CeC2 can be precipitated in cast steel and distributed along the grain boundaries. Heat treating the steel as austenite, the CeC2 transformed into ternary compound Fe4Ce4 C7, its thermodynamics of formation in steel being expressed as: ac exp(6400/T-6. 28), where 1015K<T<1523K and ac 0.126. Fe4Ce4C7 in steel is primitive tetragonal, anisotmpic in polarized light, opaque in dark field and a little greyer than iron matrix in bright field. Its Vickers hardness is about 420kg/mm2 (annealed) and 750kg/mm2 (quenched). This phase in steel is stable in basic and organic solutions and can be seperated from the matrix by electrolysis. Moreover, the LaC2 in steel can not be transformed into Fe-La-C ternary compound in present investigation.
文摘Polycrystalline Ce_(0.95)Ca_(0.05)F_(2.95) was prepared by a conventional solid-state reaction. The heat stability and ion conductivity of Ce_(0.95)Ca_(0.05)F_(2.95) were investigated by a high temperature calorimeter and an ac impedance technique. Experimental results indicate that Ce_(0.95)Ca_(0.05)F_(2.95) is stable at temperatures below 1000 K and represents the ionic conductivity of 1×10^(-3) to 10^(-1) Ω^(-1)·cm^(-1) in temperature range of 660 to 1180 K.
