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Epitaxial growth of cobalt islands via oxide mediated epitaxy
Stará, Veronika ; Kolíbal, Miroslav (referee) ; Čechal, Jan (advisor)
This bachelor thesis deals with preparation, growth and analysis of cobalt thin films. The films are formed on silicon (111) samples covered with a thin layer of native oxide SiO2. Cobalt thin films were prepared using oxide mediated epitaxy method with the effusion cell as a source of cobalt atoms. Composition and morphology of the resulting Co system was studied as a function of the annealing temperature. Another goal of this research was to determine the dependence of the final island shape on the amount of deposited material and substrate orientation. The prepared structures were analyzed using X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. To determine the thickness of subsurface islands the samples were etched in buffered hydrofluoric acid and analyzed using above mentioned methods.
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Biocompatible titanium and cobalt alloys and their aplications
Volná, Kateřina ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
This work is written in the form of literary research and deals with titanium and cobalt alloys and their application in dental medicine. Production of the individual metals, their mechanic, physical as well as chemical characteristics and various alloys which these elements can form are described in the first part. Furthermore, biocompatibility and basic division of biocompatible materials are explicated here. The work also deals with the basic requirements placed upon the materials used in dental medicine. Subsequently, five particular alloys are introduced: Ti-6Al-4V, Nitinol, Oralium, Oralium Ceramic and Ceramill Sintron and their characteristics and usage are described. In conclusion, the individual metals and their alloys are evaluated.
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Spectral analyzing and characterization of magnetic atoms and investigating superconducting films in low temperature STM
Cahlík, Aleš ; Jelínek,, Pavel (referee) ; Šikola, Tomáš (advisor)
This work is divided in two thematic parts. The first part shows a refurbishment of a Omicron low temperature STM set-up and its utilization for preparation of superconducting-magnetic interfaces. First, a cleaning procedure of suitable metallic substrates, specifically W(110) and Ir(111), is shown. It is followed by results of iron monolayer deposition on Ir(111) (Fe-Ir(111) interface). The last section deals with study of vanadium growth on pure Ir(111) substrate as well as on mentioned Fe-Ir(111) interface. The second thematic part deals with magnetism of cobalt atoms on a monolayer metal dichalcogenide WS2. It focuses primarily on studying their magnetic moment and magnetic anisotropy using X-ray magnetic circular dichroism (XMCD).
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Deposition of magnetic nanostructures using EBID and optimalization of their chemical composition and morphology
Vyroubal, Ondřej ; Kolíbalová, Eva (referee) ; Kolíbal, Miroslav (advisor)
This master's thesis deals with deposition of cobalt nanostructures using Electron Beam Induced Depositon (EBID). The thesis firstly describes theoretical background regarding EBID. In the following experimental part, the deposition process is optimized via analysis of exposition parameters and their influence on the final shape of nanostructures. These are analyzed via Atomic Force Microscopy (AFM). Optimized exposure parameters are then applied to the deposition of functional 3-dimensional nanostrucutres. In particular, the deposition of cobalt spheres. The elemental composition is analyzed by the means of element composition using Energy-dispersive X-ray Spectroscopy (EDX) and the nanostructures of desired morphologies are studied with Magnetic Force Microscopy (MFM) and Magneto-Optical Kerr Microscope).
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Concentration of cobalt in wastewater and its removal using a constructed wetland
PIVONKOVÁ, Eliška
The presented bachelor's thesis discusses monitoring of wastewater in a vegetation wastewater treatment plant in the village Slavošovice, Czech Republic and an efficiency of cobalt removal from wastewater. Cobalt concentration in wastewater was determined using the atomic absorption spectrometry. The analyzed wastewater samples were taken from different parts of the constructed wetland's system in the period from March to September 2015. The obtained results enabled to calculate the efficiency of cobalt removal from wastewater.
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Ellipsometry of Thin Films
Novotný, Zbyněk ; Navrátil, Karel (referee) ; Nebojsa, Alois (advisor)
Diploma thesis deals with ageing process of thin films of Co and Cu on Si substrate, prepared by the IBAD method. The process of film ageing, which depends on time of exposition to the atmosphere at room conditions, was investigated with spectroscopic ellipsometry (VIS+UV) and atomic force microscopy. In case of thin Co films, approximately four days long incubation period was observed. During this time period, a change in the optical parameters of the film occurs without a measurable change of the film topography. Using non-contact atomic force microscopy, a growth of the transitional film in the island growth regime was observed. During the ageing of thin Cu films, two stages of growth of the transitional layer were observed - nucleation stage and growth stage. Both of these time periods of the transitional layer growth show direct logarithmic dependence. Using non-contact atomic force microscopy, the growth of the transitional film was observed. Using atomic force microscopy in non-contact regime, time dependent measurement was done and the process of forming of one monolayer of the transitional layer was documented. Within the diploma thesis, a series of experiments on ultra high vacuum system were performed in order to investigate phase transformation of thin Fe films (22 monolayers) on Cu(100) stabilized by CO absorption. The transformation from fcc phase to bcc phase was induced by Ar+ ion beam bombardment with the ion energy in the range (0.5-4) keV. The process of phase transformation was observed by surface magneto-optic Kerr effect, Auger electron spectroscopy and low energy electron diffraction.
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Selective growth of metallic materials.
Šimíková, Michaela ; Schneeweiss, Oldřich (referee) ; Čechal, Jan (advisor)
The diploma thesis deals with selective growth of cobalt thin films on lattices created by focused ion beam on Si(111) substrates with thin film of silicon dioxide. Further, the growth and morphology of iron thin films growing on Si/SiO2 substrate without modification was studied. In the last part, thin film of a-C:H, influence of preparation parameters on their growth and ratio of sp2 and sp3 bonds, was investigated. For analysis of those films XPS, AFM, and SEM metods were used.
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The influence of cobalt additive on parameters of positive electrode for Ni-Cd accumulators
Svoboda, Michal ; Svoboda, Vít (referee) ; Špičák, Petr (advisor)
The Master´s thesis deals with description of the influence of cobalt additive on positive electrode parameters for Ni-Cd accumulators. Trough the use of Electrochemical Quartz Crystal Microbalance are analysed the effects which decline effective life of positive electrode during accelerated cycling. Theoretical part describes important characteristics of Ni-Cd accumulators, the working principle and effects which are in progress on positive electrode during cycling. The next part deals with description of system EQCM and the pricnciples of doping active mass with cobalt additive. Practical part consists of EQCM system calibration and electrochemical measurements. The principal aim is detection of the influence of cobalt additve on active mass during cycling in different electrolytes. From the results of measurements is set the optimal amount of cobalt additive.
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Microdetermination of cobalt by methods of molecular and atomic absorption spectrometry
Charuza, Martin ; Řezáčová, Veronika (referee) ; Sommer, Lumír (advisor)
This diploma thesis is focused on microdetermination of cobalt by UV-VIS spectrophotometry with organic agents and comparison with atomic absorption spectrometry. In the first part properties, occurance and importance of cobalt in the environment are desribed, complete with as a part of vitamine B12. Attention is also given to cobalt compounds, especially in the oxidative states +II and +III. Methods of preconcentration and preparation cobalt determination in real samples are adduced. In this thesis are described some optical analytical methods with accept on spectrophotometric agents for determination of cobalt. The experimental part of this thesis icludes optimalization of the spectrophotometric determination of cobalt with choosen organic agents 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol and optimalization of atomic absorption spectrometry for cobalt determination. All of real samples of water (surface, underground, mineral and waste) were measured by both 4-(2-pyridylazo)resorcin and 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol via UV-VIS and via atomic absorption spectrometry. Results of determinations were compared. A sample of vitamine B12 was measured too by all techniques.
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