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α-Fe nanočástice připravené rozkladem pentakarbonylu železa v mikrovlnném výboji
David, Bohumil ; Pizúrová, Naděžda ; Schneeweiss, Oldřich ; Hoder, T. ; Kudrle, V. ; Janča, J.
The nanocrystalline iron powder has been prepared by the introducing of Fe(CO)5 vapor into the microwave induced argon discharge. A microwave 2.45 GHz source was operated at 430 W. The reaction was performed in a quartz tube passing through the microwave waveguide. The in-situ passivation using air was applied after synthesis. The powder was characterised by TEM, XRD, and Mössbauer spectroscopy. According to our TEM investigation, the produced passivated powder included aggregated core-shell nanoparticles. The cores consist of α-Fe and the shell is supposed to be iron oxide (indicated by TEM). The presence of α-Fe and iron oxides was confirmed by XRD and Mössbauer spectroscopy. The mean coherence domain size of α-Fe cores was estimated to be 30 nm. The synthesized nanopowder exhibits ferromagnetic behaviour.
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Použití mikrovlnného plazmatu pro syntézu alfa-Fe nanočástic
Hoder, T. ; Kudrle, V. ; Frgala, Z. ; Janča, J. ; David, Bohumil
Microwave induced plasma decomposition of iron pentacarbonyl has been used to prepare iron nanosized particles. Vapours of iron pantacarbonyl have been introduced into argon surfaguide discharge, optical mission spectra have been taken and rotational and vibrational temperatures obtained. The temperatures were plotted as a functions of axial and radial distance and of iron pentacarbonyl concentration. Iron nanoparticles have been produced, XRD results and TEM images were obtained. The core-shell nanoparticles were observed, with alpha phase iron as a core and Fe(x)O(y)/C shell.
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Characterization of Supported Nanoparticles by Photoelectron Spectroscopy Methods
Bastl, Zdeněk ; Spirovová, Ilona
The study of low-dimensional materials has taken a broad importance due to the fundamental as well as technological interests. Metal nanoparticles are objects that occupy a special place between free atoms and three-dimensional systems [1]. The electronic structure of nanoparticles and their physico-chemical properties are of primary importance in their applications in heterogeneous catalysis, gas sensors, magnetic devices, etc. In the case of supported nanoparticles the influence of the substrate can modify significantly their electronic structure and induce special structures, leading thus to changes of properties important for applications. Because of high surface to volume ratio surface chemistry is crucial to control many properties of nanoparticles.
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