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Nicotine destruction on different photoactive catalysators
Brožek, Vlastimil ; Mastný, L. ; Šrank, Z. ; Eliáš, M. ; Janča, J.
We built a testing apparatus that uses IR analysis to observe the decomposition rate of nicotine from cigarette smoke on spherical or planar catalysers prepared by plasma-thermal treatment of titania-based precursors. The photocatalytic efficiency of the products of plasma-thermal treatment of metallic titanium by the WSP® plasma generator was compared with standard anatase catalysers of the Degussa AV type when destroying nicotine by application of a 366nm UV light. The results permit to consider a construction of an efficient nicotine destruction facility.
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Diamond growth on silicon and WC-Co by microwave plasma chemical vapor deposition
Frgala, Z. ; Kudrle, V. ; Janča, J. ; Buršíková, V. ; Vašina, P. ; Meško, M. ; Buršík, Jiří ; Kadlečíková, M. ; Klapetek, P.
We studied the growth of microcrystalline diamond films on pre-treated Si and WC-Co substrates by microwave plasma chemical vapor deposition.We observed the interesting time dependence of the negative bias voltage during nucleation stage which is useful for nucleation process monitoring. The layers were analysed by Raman spectroscopy, scanning electron microscopy and atomic force microscopy.
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Plazmochemická příprava olovnato-wolframové bronzi
Brožek, Vlastimil ; Janča, J. ; Eliáš, M.
Tungsten bronzes are materials based on tungsten oxide that exhibit different colours, excellent chemical resistivity, metallic appearance and good conductivity. The doped tungsten bronzes may by used as anodic catalyst in fuel cells. The tungsten bronzes are prepared by reduction of tungstates. The reduction process is known for very long time, but the correlation between their stoichiometry, conductivity and colour are not yet completely understood. The published results about colour of products are very often misleading. In this paper, we study chemical reactions between lead-tungstate and hydrogen plasma. The reduction was performed in an inductively coupled r.f. discharge. The r.f. generator operated at the frequency of 27 MHz with the power output of 1 kW. The PbWO4 was heated by the discharge to the temperature of 900°C. The resulting samples were analysed by SEM, XRD and three point L*a*b* method. The XRD spectra of our plasmachemical product show diffraction patterns of metal tungsten and lead-tungstate bronze with a cubic phase similar to Pb0,261WO3 (P4/mbm). The diffraction peaks of original lead-tungstate bronze are higher for the sample reduced only 60 min than for 120 min. To obtain data for process kinetics observation, further experiments were performed with ground lead-tungstate powder at two size fractions. Analytical balance, after determining the W and Pb content, showed the bronze composition to be most likely close to Pb 1-X = 0,225.
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Interakce vodíkového plazmatu s ferity
Hofman, R. ; Vacík, M. ; Brožek, Vlastimil ; Eliáš, M. ; Janča, J.
Ferrites are a well-known ferroelectric materials based on metal oxides with different oxidation levels. They found thanks its advisable properties a broad field of exercise, especially in electronics. In our work we made an effort to amplify this field of exercise. An intention of our work was explaining how the ferrites behave in strongly reducing atmosphere realized in hydrogen plasma. The emphasis was laid on readiness and selectivity of reduction. And further we are interested in morphology and granulometry of obtained products and last but not least in mechanical properties, especially of obtained ceramics composite with metal matrix ( MMC
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