We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite(α-Fe_(2)O_(3))nanostructures based on electrical resistive heating of iron wire under ambient conditions.Typically,1-5μm l...We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite(α-Fe_(2)O_(3))nanostructures based on electrical resistive heating of iron wire under ambient conditions.Typically,1-5μm longα-Fe_(2)O_(3)nanowires were synthesized on a time scale of seconds at temperatures of around 700℃.The morphology,structure,and mechanism of formation of the nanowires were studied by scanning and transmission electron microscopies,energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and Raman techniques.A nanowire growth mechanism based on diffusion of iron ions to the surface through grain boundaries and to the growing wire tip through stacking fault defects and due to surface diffusion is proposed.展开更多
Single-walled carbon nanotubes （SWNTs） have been grown on a silica-supported monometallic nickel （Ni） catalyst at temperatures ranging from as low as 450℃to 800℃. Different spectroscopic techniques, such as Rama...Single-walled carbon nanotubes （SWNTs） have been grown on a silica-supported monometallic nickel （Ni） catalyst at temperatures ranging from as low as 450℃to 800℃. Different spectroscopic techniques, such as Raman, photoluminescence emission （PLE）, and ultra violet-visible-near infrared （UV-vis-NIR） absorption spectroscopy were used to evaluate file diameter and quality of the SWNTs grown over the Ni catalyst at different temperatures. The analysis revealed that high quality SWNTs with a very narrow diameter distribution were obtained at a growth temperature of 500 ℃. In the PLE and absorption spectra, differences were observed between the SWNTs grown oil Ni and those grown on cobalt （Co）. This result expands the potential of growing a specific （n, m） tube species with relatively high abundance by tuning the catalyst composition. Furthermore, the prerequisites for the low temperature growth of SWNTs over a monometallic transition metal catalyst have been elucidated.展开更多
基金the Academy of Finland(project numbers 128445 and 128495)P.R.M.acknowledges Finnish National Graduate School in Nanoscience(NGS-NANO)S.D.S.thanks the European Commission for financial support through a Marie Curie Individual Fellowship(MIF1-CT-2005-022110).
文摘We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite(α-Fe_(2)O_(3))nanostructures based on electrical resistive heating of iron wire under ambient conditions.Typically,1-5μm longα-Fe_(2)O_(3)nanowires were synthesized on a time scale of seconds at temperatures of around 700℃.The morphology,structure,and mechanism of formation of the nanowires were studied by scanning and transmission electron microscopies,energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and Raman techniques.A nanowire growth mechanism based on diffusion of iron ions to the surface through grain boundaries and to the growing wire tip through stacking fault defects and due to surface diffusion is proposed.
文摘Single-walled carbon nanotubes （SWNTs） have been grown on a silica-supported monometallic nickel （Ni） catalyst at temperatures ranging from as low as 450℃to 800℃. Different spectroscopic techniques, such as Raman, photoluminescence emission （PLE）, and ultra violet-visible-near infrared （UV-vis-NIR） absorption spectroscopy were used to evaluate file diameter and quality of the SWNTs grown over the Ni catalyst at different temperatures. The analysis revealed that high quality SWNTs with a very narrow diameter distribution were obtained at a growth temperature of 500 ℃. In the PLE and absorption spectra, differences were observed between the SWNTs grown oil Ni and those grown on cobalt （Co）. This result expands the potential of growing a specific （n, m） tube species with relatively high abundance by tuning the catalyst composition. Furthermore, the prerequisites for the low temperature growth of SWNTs over a monometallic transition metal catalyst have been elucidated.
