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Functional TiO2 layers on fiber structures
Bečár, Tomáš ; Chladil, Ladislav (referee) ; Bača, Petr (advisor)
This thesis deals with the formation of functional layers on fibrous structures. The aim of the thesis is to deposit a titanium dioxide film on glass fibres for its use as an additive in lead acid batteries. The work includes a survey of methods of titanium dioxide deposition on glass substrate, a review of measuring and recording equipment and a structural analysis of the materials used. As a result of the work, experiments of titanium dioxide deposition on filter paper and glass fibers will be developed along with their analysis. The evaluation of the analyses will be followed by a proposal for the use of these functional layers in possible applications.
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Evaluation of the effect of chelating agents on the properties of phosphate coatings on AZ31 magnesium alloy prepared by hydrothermal method
Molva, Vojtěch ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The aim of this bachelor thesis was to evaluate the influence of chelating agents on the properties of CaP coatings deposited on the AZ31 magnesium alloy by hydrothermal method. The theoretical part deals with magnesium and its alloys useful not only in biomedicine. Subsequently, the possibilities of surface treatments in the field of biomedical applications are described, with a focus on calcium phosphate (CaP) coatings. The theoretical part further discusses these coatings and the influence of selected chelating agents on the formation of CaP coatings. The theoretical part is concluded with a review of the experiments already carried out for the preparation of CaP coatings on Mg alloys. The experimental part includes the preparation and analysis of the protective Mg(OH)2 layer necessary for the deposition of CaP coatings. Within the experimental part, the influence of chelating agents (Chelaton III, citric acid, magnesium gluconate hydrate) at concentrations of 5, 50, and 500 mM at different pH of the reaction mixture on the structure, morphology, composition, and quality of the prepared CaP coatings was studied. The morphology, structure, and composition of the deposited coatings were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Based on these analyses, an assessment of the quality of the coatings was performed. In terms of coating quality, the coating prepared with the addition of 50 mM of Chelaton III at pH 7 and with the addition of 5 mM of magnesium gluconate hydrate at pH 5 appeared to be the best. The corrosion resistance was investigated by potentiodynamic tests in 0.15M NaCl, always with the sample from each batch that showed the best quality. The corrosion potential (Ecorr) and current corrosion density (icorr) values were determined from the polarization curves using the Tafel extrapolation method. Based on the measurements made, the most corrosion-resistant coated sample was the one with the addition of 5 mM magnesium gluconate hydrate at pH 5.
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Size evolution of spiral magnetic structure in cobalt chromite nanoparticles
Alemayehu, Adam ; Nižňanský, Daniel (advisor) ; Klicpera, Milan (referee)
Název práce: ývoj spirální magnetické chromitových nanočásticích Katedra anorganické chemie, PřF UK Vedoucí bakalářské práce: RNDr. Daniel Nižňanský, Ph. mail vedoucího: Magnetické nanomateriály hrají důležitou roli v posledních desetiletích díky zajímavým aplikacím . Multiferroické materiály jsou materiály, u nichž existují dva typy jevů, magnetické a feroelektrické uspořádání. To znamená, že se může indukovat magnetizac ým polem nebo elektrická magnetickým polem. chromitý patří do druhé skupiny feroických látek, nazývaných multiferroika typu II. Tyto eroické materiály jsou relativně nové. V případě, že v těchto materiálech existuje feroelektrika, musí být v těchto materiálech přítomen zvláštní typ magnetického uspořádání. chromitý ) krystalizuje ve struktuře kubického spinelu, kde jsou umístěny v tetraedrických a okta ický polohách zhlucích dochází k ferrimagnetickému uspořádání CoCr při systém dále prochází magnetickým fázovým přechodem uspořádání do řady magnetických spirál s dlouhým dosahem při přechodové teplotě 26 K Současně byla pozorovaná dielektrická anomálie pod spirálním magnetickým přechodem této práci je prezentován vývoj spirálového uspořádání se změnou velikosti částic. íčová slova: prášková röntgenová difrakce, difuzní rozptyl neutronů, hydrotermální metoda
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Příprava a vlastnosti nanočástic chromitů
Zákutná, Dominika ; Nižňanský, Daniel (advisor) ; Němec, Ivan (referee)
Title: Preparation and Characterization of Chromites nanoparticles Author: Dominika Zákutná Department: Department of Inorganic Chemistry, Faculty of Science, Charles University of Prague Supervisor: RNDr. Daniel Nižňanský, Ph.D. Consultant: RNDr. Jana Vejpravová, Ph.D. Supervisor`s e-mail address: niznansk@natur.cuni.cz Abstract: This work concerns the hydrothermal preparation of cobalt chromite nanoparticles (CoCr2O4), their characterization and the study of their magnetic properties. The preparation is based on the chlorides in the water-ethanol-oleic acid system. The samples were characterized by Powder X-ray Diffraction (PXRD), Transmission and High Resolution Electron Microscopy (TEM, HRTEM), Scanning Electron Microscopy (SEM), Raman and Infrared Spectroscopy and magnetic measurements of magnetization as a function of temperature and field. It was found, that furcation temperature, Tf depends on particle size. Keywords: CoCr2O4, superspin-glass like system, hydrothermal method, magnetic properties, oleates
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