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Nanostructured materials based on metal oxides - structure and thermal stability
Václavů, Tereza ; Kužel, Radomír (advisor) ; Čapková, Pavla (referee) ; Klementová, Mariana (referee)
Title: Nanostructured materials based on metal oxides - structure and thermal stability Author: Tereza Václavů Department: Department of Condensed Matter Physics Supervisor: prof. RNDr. Radomír Kužel, CSc. Abstract: The structure and temperature stability of two nanocrystalline ma- terials were studied. First, titanate nanotubes prepared by hydrothermal synthesis were studied from room temperature up to 1000 ◦ C in air and helium atmospheres and in vacuum with the aid of in situ X-ray diffraction (XRD) and calorimetry combined with electron microscopy. The nanotubes exhibit different behavior and structure transformations during heating in different atmospheres. A difference between vacuum and He atmosphere was observed; also a different final product was observed after annealing: In air, the nanorods disintegrated to nanoparticles, whereas in vacuum nanowires formed. The second material studied was a nanocrystalline particle system with an iron core protected against oxidation by an oxide layer. The structure of these nanoparticles was determined by XRD and Mossbauer spectroscopy. The tem- perature stability and induced transformations of these samples were studied by in situ XRD and X-ray small-angle scattering (SAXS). The long-time stability of the structure of these nanoparticles was studied as well;...
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2D structures based on metal phosphonates; relationships between arrangement and properties studied by molecular simulations methods
Škoda, Jakub ; Pospíšil, Miroslav (advisor) ; Čapková, Pavla (referee) ; Praus, Petr (referee)
This work deals with the structural analysis of layered zirconium sulfophenylphosphonates and their intercalates with the use of the classical molecular simulation methods. The inner composition of both fully and partially sulfonated layers was determined in agreement with available experimental data, especially chemical analysis, thermogravimetric measurements and X-ray diffraction. The calculations revealed the positions of the water molecules in the planes of sulfo groups which strongly affect the resultant diffraction pattern. Within the zirconium sulfophenylphosphonate layered structure, the arrangements of intercalated species based on optically active dipyridylamine molecules and cations of sodium, copper and iron were solved with the respect to the agreement with experimental results and values of potential energy. In case of the dipyridylamine molecules and its derivatives, the resultant disordered partially row arrangements of the organic molecules in the interlayer were showed to influence the dipole moment of the intercalate. From this point of view, nitro-derivative has been picked out as the most suitable for potential applications. Regarding the intercalated cations, sodium cations take up the space of water molecules next to the sulfo groups while copper and iron cations are distributed in a...
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2D structures based on metal phosphonates; relationships between arrangement and properties studied by molecular simulations methods
Škoda, Jakub ; Pospíšil, Miroslav (advisor) ; Čapková, Pavla (referee) ; Praus, Petr (referee)
This work deals with the structural analysis of layered zirconium sulfophenylphosphonates and their intercalates with the use of the classical molecular simulation methods. The inner composition of both fully and partially sulfonated layers was determined in agreement with available experimental data, especially chemical analysis, thermogravimetric measurements and X-ray diffraction. The calculations revealed the positions of the water molecules in the planes of sulfo groups which strongly affect the resultant diffraction pattern. Within the zirconium sulfophenylphosphonate layered structure, the arrangements of intercalated species based on optically active dipyridylamine molecules and cations of sodium, copper and iron were solved with the respect to the agreement with experimental results and values of potential energy. In case of the dipyridylamine molecules and its derivatives, the resultant disordered partially row arrangements of the organic molecules in the interlayer were showed to influence the dipole moment of the intercalate. From this point of view, nitro-derivative has been picked out as the most suitable for potential applications. Regarding the intercalated cations, sodium cations take up the space of water molecules next to the sulfo groups while copper and iron cations are distributed in a...
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Structural study of nanocrystalline titanium oxide films and their temperature stability
Chlanová, Lea ; Kužel, Radomír (advisor) ; Čapková, Pavla (referee) ; Ganev, Nikolaj (referee)
Title: Structural study of nanocrystalline titanium oxide films and their temperature stability Author: Lea Chlanová Department: Department of Condensed Matter Physics Supervisor: Prof. RNDr. Radomír Kužel, CSc., Department of Condensed Matter Physics Abstract: TiO2 thin films can exhibit photocatalytic activity and photoinduced su- perhydrophilicity depending on crystallinity, phase composition and mi- crostructure. These parameters were studied by X-ray diffraction (XRD) and reflectivity (XRR) for magnetron deposited films - nanocrystalline and amorphous, namely their temperature and time evolution. For nanocrystalline films, it was found that higher partial oxygen pressure during the deposition is beneficial. Small anatase crystallites were stable up to about 450 ◦ C. Depth-profiling XRD of some samples revealed that rutile phase was only present close to the substrate. For amorphous films it was found that the crystallization depends strongly on the film thickness and it is slower for very thin films. Evolution of the intensities of anatase diffraction peaks with annealing time could be described by a modified Avrami equation. XRD profile was relatively narrow from the very be- ginning of crystallization (at about 220 ◦ C), which indicated relatively larger crystallites (> 100 nm), and hence, nanocrystalline films...
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