Nickel nanowires with large aspect ratio of up to 300 have been prepared by a hydrazine hydrate reduction method under applied magnetic field. The diameter of nickel nanowires is about 200 nm and length up to 60 μm. ...Nickel nanowires with large aspect ratio of up to 300 have been prepared by a hydrazine hydrate reduction method under applied magnetic field. The diameter of nickel nanowires is about 200 nm and length up to 60 μm. The role of magnetic field on the growth of magnetic nanowires is discussed and a magnetic nanowire growth mechanism has been proposed. Nickel ions are firstly reduced to nickel atoms by hydrazine hydrates in a strong alkaline solution and grow into tiny spherical nanoparticles. Then, these magnetic particles will align under a magnetic force and form linear chains. Furthermore, the as-formed chains can enhance the local magnetic field and attract other magnetic particles nearby, resulting finally as linear nanowires. The formation and the size of nanowires depend strongly on the magnitude of applied magnetic field.展开更多
The Bi-2223/Ag tapes were prepared with spray-died powders, which are of different particle sizes and phase assemblages by varying the annealing time in pure oxygen. Longer time annealing degraded the reactivity of pr...The Bi-2223/Ag tapes were prepared with spray-died powders, which are of different particle sizes and phase assemblages by varying the annealing time in pure oxygen. Longer time annealing degraded the reactivity of precursor powder, which in turn resulted in an incomplete conversion from precursors to Bi-2223, porosity core and misaligned grains in fully processed tapes. The best Jc in short pressed samples varied from 29.7 to 47kA/cm2 for the tapes made from different powders.展开更多
基金supported by the Hi-Tech Research and Development Program of China(No.2007AA03Z300)Shanghai-Applied Materials Research and Development fund(No.07SA10)+3 种基金National Natural Science Foundation of China(No.50730008)Shanghai Science and Technology Grant(No:0752nm015,09ZR1414800,1052nm05500)National Basic Research Program of China(No.2006CB300406)the fund of Defence Key Laboratory of Nano/Micro Fabrication Technology
文摘Nickel nanowires with large aspect ratio of up to 300 have been prepared by a hydrazine hydrate reduction method under applied magnetic field. The diameter of nickel nanowires is about 200 nm and length up to 60 μm. The role of magnetic field on the growth of magnetic nanowires is discussed and a magnetic nanowire growth mechanism has been proposed. Nickel ions are firstly reduced to nickel atoms by hydrazine hydrates in a strong alkaline solution and grow into tiny spherical nanoparticles. Then, these magnetic particles will align under a magnetic force and form linear chains. Furthermore, the as-formed chains can enhance the local magnetic field and attract other magnetic particles nearby, resulting finally as linear nanowires. The formation and the size of nanowires depend strongly on the magnitude of applied magnetic field.
文摘The Bi-2223/Ag tapes were prepared with spray-died powders, which are of different particle sizes and phase assemblages by varying the annealing time in pure oxygen. Longer time annealing degraded the reactivity of precursor powder, which in turn resulted in an incomplete conversion from precursors to Bi-2223, porosity core and misaligned grains in fully processed tapes. The best Jc in short pressed samples varied from 29.7 to 47kA/cm2 for the tapes made from different powders.
