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Surface changes induced by plasma treatment and high temperature annealing of silicon dioxide microparticles
Babčenko, Oleg ; Remeš, Zdeněk ; Beranová, Klára ; Kolářová, Kateřina ; Lörinc, J. ; Prošek, Z. ; Tesárek, P.
Due to the high surface to volume ratio, the particles’ surface properties modification defines its properties in general, which is crucial for their use. From this point of view, plasma processing or high temperature annealing can be considered as the universal techniques for efficient modification of materials in the form of powder. In this study, the silicon dioxide microparticles have been treated in a hydrogen, oxygen or vacuum by low temperature plasma or annealing. The change of SiO2 microparticles properties was investigated by photoluminescence spectroscopy at room and low temperature. High temperature annealing in hydrogen induced under UV excitation photoluminescence in the near UV and visible light indicating the change of defect states on the surface of the microparticles. We believe that observed findings clearly demonstrate useful method for analysis of SiO2 microparticles surface modification attractive also for fundamental research.
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Enhanced growth rate of diamond films at low temperature in focused microwave plasma system
Babčenko, Oleg ; Bydžovská, Irena ; Fait, Jan ; Shagieva, Ekaterina ; Ondič, Lukáš ; Kromka, Alexander
The low temperature (< 500 °C) diamond film deposition on fused silica in two different focused microwave plasma systems, i.e. a multimode clamshell cavity (MCC) and a rotational ellipsoid cavity (REC) reactor, was investigated. During the experiments, the methane to hydrogen ratio, in the hydrogen-rich process gas mixture, varied from 1 % to 15 % for MCC and from 1 % to 9 % for REC. The grown films were analyzed by scanning electron microscopy and Raman shift measurements. The outcomes of the study and enhanced diamond growth at low temperatures is advantageous for overcoating of fused silica as well as thermally sensitive substrates, e.g. optical elements, photonic crystals, sensors, etc.
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