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Užití elektronové difrakce k mapování elastického napětí
Ondračka, Václav ; Kuběna, Ivo (oponent) ; Spousta, Jiří (vedoucí práce)
Metoda difrakce zpětně odražených elektronů je známou a běžně používanou metodou k určení orientace a velikosti zrn. Její použití pro mapování elastické deformace a ro- tace způsobené plastickými deformacemi tak rozšířené není. Tato diplomová práce se věnuje popisu standardního EBSD systému. Poznatků o použitých soustavách, notace orientace zrn a kalibrace systému je pak využito pro vytvoření svobodného softwaru pro mapování elastické deformace a rotace v rámci jediného zrna nebo monokrystalu, pracujícího s daty získanými z komerčních EBSD systémů.
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Phase plates for transmission electron microscopy
Špičáková, Tereza ; Sháněl, Ondřej (oponent) ; Konečná, Andrea (vedoucí práce)
Samples consisting of light atoms, such as biological samples, provide low contrast in the transmission electron microscope images. However, introducing an additional phase shift between the electrons carrying the information of the sample and the background electrons can enhance the contrast significantly without impacting the quality of the image. This effect can be achieved by using a phase plate in the microscope. Phase plates based on a thin amorphous carbon film are used in conventional transmission electron microscopes. In recent years, extensive research in advanced phase plate design has been carried out. Yet, only a few studies on materials for the thin film-based phase plates have been published. For this reason, the main goal of this master’s project is to design measurements of the phase-shifting properties of various materials. In the first part of this thesis, the theory of electron wave imaging in a transmission electron microscope is described. Then, we review and compare phase plate designs. In the second part, four designs of the experimental setup are presented, out of which two have been tested experimentally. The measurements have been performed on a series of samples of different thicknesses and materials, and the results have been appropriately analysed. Furthermore, the qualitative behaviour of the tested designs has been compared to theoretical computations.
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Phase plates for transmission electron microscopy
Špičáková, Tereza ; Sháněl, Ondřej (oponent) ; Konečná, Andrea (vedoucí práce)
Samples consisting of light atoms, such as biological samples, provide low contrast in the transmission electron microscope images. However, introducing an additional phase shift between the electrons carrying the information of the sample and the background electrons can enhance the contrast significantly without impacting the quality of the image. This effect can be achieved by using a phase plate in the microscope. Phase plates based on a thin amorphous carbon film are used in conventional transmission electron microscopes. In recent years, extensive research in advanced phase plate design has been carried out. Yet, only a few studies on materials for the thin film-based phase plates have been published. For this reason, the main goal of this master’s project is to design measurements of the phase-shifting properties of various materials. In the first part of this thesis, the theory of electron wave imaging in a transmission electron microscope is described. Then, we review and compare phase plate designs. In the second part, four designs of the experimental setup are presented, out of which two have been tested experimentally. The measurements have been performed on a series of samples of different thicknesses and materials, and the results have been appropriately analysed. Furthermore, the qualitative behaviour of the tested designs has been compared to theoretical computations.
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Užití elektronové difrakce k mapování elastického napětí
Ondračka, Václav ; Kuběna, Ivo (oponent) ; Spousta, Jiří (vedoucí práce)
Metoda difrakce zpětně odražených elektronů je známou a běžně používanou metodou k určení orientace a velikosti zrn. Její použití pro mapování elastické deformace a ro- tace způsobené plastickými deformacemi tak rozšířené není. Tato diplomová práce se věnuje popisu standardního EBSD systému. Poznatků o použitých soustavách, notace orientace zrn a kalibrace systému je pak využito pro vytvoření svobodného softwaru pro mapování elastické deformace a rotace v rámci jediného zrna nebo monokrystalu, pracujícího s daty získanými z komerčních EBSD systémů.
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Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Řiháček, Tomáš ; Horák, M. ; Schachinger, T. ; Matějka, Milan ; Mika, Filip ; Müllerová, Ilona
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place almost solely in connection with transmission electron microscopes (TEM). On the other hand, although scanning electron microscopes (SEM) may provide some advantages for EVB applications, only little attention has been dedicated to them. Therefore, the aim of this work is to create electron vortices in SEM at energies of several keV.
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Nanodisperzní oxidy a hydroxidy Mg, Al a Ti
Šubrt, Jan ; Štengl, Václav ; Svobodová, Monika ; Bezdička, Petr ; Kváča, Zdeněk ; Večerníková, Eva ; Bakardjieva, Snejana
Z organických prekursorů a cestou homogenního srážení byly připraveny nanočásticové oxidy a hydroxidy Mg, Al, Ti a Fe. Hydroxidy byly zpracovány metodou sušení nad kritickou teplotou a charakterizovány pomocí elektronové mikroskopie a difrakce, změření specifického povrchu, práškovou rentgenovou difraktometrií a termickou analýzou.
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