|
|
Fabrication and study of epitaxial NiO thin films and their antiferromagnetic domain structure
Opršal, Jakub ; Caha, Ondřej (referee) ; Staňo, Michal (advisor)
Antiferomagnetické materiály získaly v posledních letech velkou pozornost díky svému uplatnění ve spintronice. NiO je dobře známý antiferomagnet a jeho Néelova teplota je nad pokojovou teplotou. Díky tomu je ideálním systémem pro studium antiferomagnetických domén. Pomocí reaktivního magnetronového naprašování jsme připravili tenké epitaxní vrstvy NiO na substrátech MgO (001) a safír (0001). Studovali jsme vliv jak substrátu tak depozičních parametrů na výslednou krystalovou a magnetickou strukturu. Použili jsme zobrazování pomocí magneto-optického dvojlomu, které slouží jako přístupnější alternativa k lineárnímu rentgenovému dichroismu pro pozorování T domén. Sestavili jsme laserovou soustavu a pomocí ní provedli experimenty zaměřené na optickou kontrolu antiferomagnetických domén.
|
|
|
Study of multilayer perovskite structures properties
Gabzdyl, Adam ; Kratochvíl, Matouš (referee) ; Pospíšil, Jan (advisor)
The bachelor thesis focuses on the optical, electrical and dielectric properties of perovskites and their multilayer structures for use in optoelectronic applications. Samples of lead MAPbI3 and lead-free Cs3Bi2I9 perovskite in a photovoltaic cell of FTO/SnO2/perovskite/spiro-OMeTAD/Au structure were prepared and studied. The optoelectrical properties were determined by direct current measurement of current-voltage characteristics and the dielectric properties were determined by impedance spectroscopy. It was determined that with this photovoltaic cell structure, lead perovskites are a more suitable material for optoelectronic applications than lead-free perovskites because they exhibit many times higher solar energy conversion efficiency and possess more favorable electron processes.
|
|
|
Material printing of UVB disposable dosimeter
Fryčová, Gabriela ; Ettler,, Karel (referee) ; Veselý, Michal (advisor)
The aim of the bachelor's thesis was the preparation of photosensitive layers responding by colour change to the exposure dose and their subsequent calibration to UVB irradiation doses of 500 and 1 000 mJcm2 using calibration agents and layer thickness change. The experimental part focuses on the preparation and application of the layers and the study of their colour response to the exposure dose. The validity of the reciprocity law was verified. The simplicity of preparation and use of the resulting disposable UVB dosimeters was emphasized.
|
|
|
Effect of substrate and geometry on the size of the anomalous Nernst phenomenon
Golub, Dmitrii ; Zázvorka,, Jakub (referee) ; Čech, Vladimír (advisor)
Anomální Nernstův jev se týká vzniku příčného napětí v magnetických materiálech při aplikovaném podélném teplotním gradientu. Tento jev slibuje aplikace v oblasti spinové kaloritroniky a zlepšené konverze tepelné energie. Zde jsme zkoumali vliv substrátu vzorku a experimentální geometrie na anomální Nernstův jev ve vzorcích tenkých filmů permaloye napařených na substrátech. Provedli jsme studii anomálního Nernstova jevu na vzorcích s čtyřmi různými substráty s podstatně odlišnou tepelnou vodivostí. Kromě toho jsme testovali čtyři různé techniky generování teplotního gradientu ve vzorcích: tři metody pro generování gradientu v rovině a jednu metodu pro generování gradientu mimo rovinu. Pozorujeme, že tepelná vodivost substrátu významně ovlivňuje velikost teplotního gradientu. V dvou konfiguracích v rovině jsme naměřili konzistentní koeficient anomálního Nernstova jevu, gradient teploty mimo rovinu byl odhadnut na základě získaných dat.
|
|
|
Preparation and charakterization of WO3 layers by brick and mortar method
Blecha, Tomáš ; Pekárková, Jana (referee) ; Králová, Marcela (advisor)
This master’s thesis deals with thin films of tungsten trioxide, which are prepared by combining nanoparticles and a binder. The composite consisted of either milled WO3 nanoparticles of different sizes or the combination of milled nanoparticles and dopamine stabilized peroxotungstic acid. The prepared compositions with the addition of templating agent polyethylene glycol were deposited on conductive FTO glass by spin coating method and further used as a photoanode in a photoelectrochemical cell. This work then focuses on studying the influence of the milled particle size and the amount of binder in the composition on the physicochemical properties of WO3 photoanodes in an attempt to measure the highest photocurrrents.
|
|
|
Photocatalytic activity of printed hybrid layers of titanium dioxide
Sýkorová, Kateřina ; Krystyník, Pavel (referee) ; Veselý, Michal (advisor)
The main aim of this thesis was to optimalise composition of the titanium dioxide with a silica binder deposited on a PET foil. Emphasis was put on achieving maximum possible adhesion and hardness of the layer and the effect on photocatalytic activity. For the evaluation of photocatalytic activity comparative experiments with prepared layers were performed. Benzoic acid, dimethyl sulfoxide and azo dye Acid Orange 7 were used as model pollutants. Photocatalytic activity was investigated using UV-VIS spectrophotometry, formal rate constants and degree of conversion were also determined. The study results can be used for removing water pollutants from the water solution.
|
|
|
Application of correlative AFM/SEM microscopy
Hegrová, Veronika ; Fejfar, Antonín (referee) ; Konečný, Martin (advisor)
This thesis is dealing with application of Correlative Probe and Electron Microscopy. All measurements were carried out by atomic force microscope LiteScope which is designed especially to be combined with electron microscopes. Advantages of Correlative AFM/SEM Microscopy are demonstrated on selected samples from field of nanotechnology and material science. Application of the correlative imaging was proposed and then realized particularly in case of low-dimensional structures and thin films. Further, this thesis deals with the possibility of combining Correlative AFM/SEM Microscopy with other integrated techniques of an electron microscope such as Focused Ion Beam and Energy Dispersive X-rays Spectroscopy.
|
|
|
Metallization of technical plastics for lightweight traffic components with reduced fuel consumption
Sanetrníková, Dominika ; Boušek, Jaroslav (referee) ; Šimůnková, Helena (advisor)
The beginning of this thesis is dedicated to polymeric materials, which include plastics an composites. Plastics are shortly divided into two groups, thermoplastics and thermosets. The following part is the use of plastics and composites in traffic industry and briefly this work focuses on techniques of recycling of this materials. This work also focuses on the techniques of thin film deposition, electroless plating, electrodeposition as well and plating in the vacuum environment. special techniques of thin film deposition are also mentioned shortly. The coatings of polymer including cleaning and surface activation is introduced using various techniques including plasma treatment. The surface treatment of polyetheretherketone (PEEK) is included too. The final part describes performed experiments and discussion of results.
|
|
|
Plasmachemical deposition and characterization of hexamethyldiloxane thin layers
Blahová, Lucie ; doc. Mgr. Vít Kudrle. Ph.D. (referee) ; Krčma, František (advisor)
Thin films have been used to modify surface properties of various materials for many years. Plasma Enhanced Chemical Vapor Deposition (PECVD) is one of the possible methods for their preparation and this technique is applied in this work as well. An organosilicone – hexamethyldisiloxane – is used as precursor. Thin films are created on the surface of the substrate using mixture of precursor and oxygen in radiofrequently excited capacitively coupled plasma. The aim of the thesis is to find the optimal deposition conditions for production of transparent thin layers with good barrier capabilities, low oxygen transmission rate especially. Thin film depositions were realized for different compositions of the deposition mixture in continuous and pulsed mode of plasma with varying supplied power and duty cycle values. The deposition process itself was monitored in situ by optical emission spectroscopy. Thin film coatings were analyzed to determine their physical chemical properties (infrared spectroscopy, surface energy) and barrier properties. Using optical emission spectroscopy, important particles were identified in the deposition plasma. Vibrational, rotational and electron temperatures were determined from relative intensities of chosen fragments. Composition of thin films was studied by infrared spectroscopy. The best results of oxygen transmission rate were achieved with layers prepared from deposition mixture with high oxygen content. It was possible to improve barrier properties by performing deposition in pulsed plasma mode with 20–30% duty cycle. In this diploma thesis, optimal deposition conditions of thin films from hexamethyldisiloxane with low oxygen transmission rate were determined. It is possible to use these results in practical applications, such as corrosion inhibitors for archaeological objects. Optionally, they can be used in various industry branches where it is desirable and feasible to prevent oxygen access to the material by deposition of barrier coatings.
|
|
|
Preparation of photocatalytically active layers of titanium dioxide
Šeffer, Lukáš ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
This bachelor work gives an overview about preparation of titanium dioxide and silicon dioxide thin films by sol-gel process, using coating methods as spin coating, dip coating, capillary and cell coating, flow coating, spray coating, pyrosol process, chemical vapour deposition and printing. The procedures of composite films preparation obtained by mixed sols of titanium dioxide and silica dioxide are also discussed together with preparation of double layer films, when titanium dioxide is coated on glass substrate covered by a silica dioxide layer. The methods of photocatalytic activity testing are the important part of this work.
|
guest ::
