National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Preparation and characterisation of selected d and p elements carbides
Nižňanský, Matěj ; Tyrpekl, Václav (advisor) ; Vilémová, Monika (referee)
This thesis is focused on carbide ceramics synthesis, more specifically on the synthesis of a Ti2AlC MAX Phase carbide using solution chemistry rather than powder metallurgy. Chloride and nitrate precursors have been used as a source of metals and citric acid as a source of carbon for carbothermal reduction and as a complexing agent. A new route of precursor synthesis has been developed based on peroxo-titanic acid, which helps retain aluminium. The syntheses were performed using the SPS facility to ensure high heating rates. Al4C3 and TiC carbides and their mixtures were prepared successfully. However, the Ti2AlC phase was not synthesized under used conditions. The phase composition, structure and grain sizes of the samples were investigated by powder X-ray diffraction, X-ray fluorescence and electron microscopy. The contents of carbon in the precursors were determined by thermogravimetric analysis.
Study of proton conductivity on powder samples
Nižňanský, Matěj ; Havlíček, David (advisor) ; Kubíček, Vojtěch (referee)
The focus of this thesis is the synthesis and characterisation of one newly prepared and one previously prepared compound which based on the results of x-ray structure analysis both contain systems of conveniently long hydrogen bonds. These systems potentially allow proton transfer through their structure. The results acquired by measuring proton conductivity of the newly prepared substance are also discussed in this thesis. Furthermore, it contains the results of the characterisation of both prepared substances by IR spectroscopy, powder x-ray diffraction and diffraction on monocrystal. The measurement of proton conductivity was carried out using tablets consisting of pressed powder samples which had gold-palladium alloy electrodes applied to them. The specific conductivity of these samples was determined by the measured electric resistance and the size of these tablets. Based on the conducted measurements, it can be stated that the newly synthesised substance does not exercise proton conductivity within the detection limit of used hardware, whereas the previously prepared one does. These results are further discussed in corresponding chapter considering primarily the structure of both substances.

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1 Nižnanský, Matúš
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