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National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Preparation of nanoparticles of transition metals and their oxides using gas aggregation sources
 Hanková, Adéla ; Kylián, Ondřej (advisor) ; Khalakhan, Ivan (referee)
This work focuses on the synthesis of nanoparticles of vanadium, titanium and their oxides. Magnetron-based gas aggregation source was used for nanoparticle preparation. Metallic nanoparticles of vanadium and titanium deposited on substrate were heated at atmospheric pressure which transformed them into oxides. Metallic and oxide nanopar- ticles are compared in terms of morphology, chemical composition, crystal structure and optical properties. Oxidation of vanadium nanoparticles during short heating times at the temperature of 450 řC is discussed in more detail. It was demonstrated, that ideal heating time for VO2 preparation is 60 s, the most stable vanadium oxide phase - V2O5 - is formed after longer heating. The change of electrical and optical properties with tem- perature (thermochromic behaviour) was monitored for VO2 nanoparticles. The V2O5 and TiO2 nanoparticles were tested for their photocatalytic effect and possible use as substrates for surface-enhanced Raman spectroscopy (SERS). It was shown that TiO2 nanoparticles coated with a thin silver layer can be used as recyclable, enhancing SERS substrates. 1
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Synthesis of nanoparticles using gas aggregation sources
 Hanková, Adéla ; Kylián, Ondřej (advisor) ; Shukurov, Andrey (referee)
This work focuses on the synthesis of thin films and nanoparticles of vanadium and its oxides. Thin films are fabricated by means of magnetron sputtering, while for the prepara- tion of nanoparticles a gas aggregation source is used. Produced thin films and nanopar- ticles are investigated and compared in terms of their morphology, optical properties and chemical structure. We also study the heating of both types of samples. All em- ployed diagnostics methods prove that oxidation of films and nanoparticles at 550 řC changes the samples to crystalline V2O5. Another investigated method of vanadium oxide nanoparticles preparation is based on the addition of oxygen into the deposition chamber. Changes in shape, size, bulk composition and thickness of the deposited layer of nanoparticles are demonstrated in comparison with nanoparticles fabricated in a pure argon atmosphere. On the other hand, the surface composition is similar for both meth- ods of preparation indicating spontaneous oxidation of the surface layer of both materials on ambient air. 1
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