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Electrical characteristics of graphene layers and their use as gas sensors
Kučera, Štěpán ; Kaspar, Pavel (referee) ; Macků, Robert (advisor)
This bachelor thesis focuses on the general characterization and description of graphene and related nanostructures. It involves production by the most used methods, including their advantages and disadvantages. Due to the impossibility of connection in the usual way, the graphene sample had to be contacted under visual inspection with a microscope with the tip contacts in the shielded area. Subsequently, it was subjected to current-voltage characterization with normal conditions on a Keithley 4200-CSC instrument. The next step was to measure the same sample under a different gas atmosphere. The result is a comparison of the specific responses to the change in gas atmosphere in which the graphene monolayer was exposed.
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Iron Functionalized Nanoparticles of Titanium Dioxide
Volfová, Lenka
Diploma thesis Iron Functionalized Nanoparticles of Titanium Dioxide Lenka Volfová 2017, ABSTRACT Iron-functionalized TiO2 were obtained by hydrolysis of aqueous solutions of titanyl sulfate with addition of ferric nitrate with ammonium hydroxide and the reaction filtered and washed with hydrogen peroxide. The colloid solutions thus prepared were lyophilized and the products were subsequently annealed at three different temperatures of 650 řC, 800 řC and 950 řC. The prepared doped materials were characterized by powder X-ray diffractometry, electron microscopy, infrared spectroscopy, Mössbauer spectroscopy, UV/VIS spectroscopy, thermogravimetric analysis and differential thermal analysis, and measurement of the specific surface area. Photocatalytic activity was determined by measuring of the decomposition of kinetics of 4-chlorophenol in an aqueous solution in the ultraviolet and visible area. For comparison of activity in the UV area and in the visible area were used a previously prepared highly photoactive specimen and standard TiO2 from Kronos, respectively. Keywords: Doped titanium dioxide, nanostructure, X-ray diffraction, electron microscopy, Mössbauer spectroscopy, suppression of photoactivity
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Structuring of plasma polymers: new methods for fabrication of nano-architectured thin films
Nikitin, Daniil ; Shukurov, Andrey (advisor) ; Novák, Stanislav (referee) ; Straňák, Vítězslav (referee)
Title: Structuring of plasma polymers: new methods for fabrication of nano-architectured thin films Author: Daniil Nikitin Department / Institute: Department of Macromolecular Physics/Charles University Supervisor of the doctoral thesis: Doc. Ing. Andrey Shukurov, PhD, Department of Macromolecular Physics/Charles University Abstract: The PhD thesis aims at the investigation of nanostructures based on plasma polymers. The main attention is paid to the combination of a gas aggregation cluster source with plasma-assisted vapor phase deposition for the fabrication of metal-polymer nanocomposites with bactericidal potential. Copper nanoparticles were incorporated into a biocompatible matrix of plasma polymerized poly(ethylene oxide) (ppPEO). The efficiency of such nanocomposite against multi-drug resistant bacteria was demonstrated. It was found that the segmental dynamics of the plasma polymer significantly changed in the presence of nanoparticles as revealed by the measurements of the dynamic glass transition temperature. The nanoscale confinement crucially influences the non-fouling properties of poly(ethylene oxide). A separate chapter is dedicated to the examination of the nanoparticle formation, growth and transport inside the source. Copper and silver nanoparticles were detected in situ in the gas phase...
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Multicomponent plasma polymers with spatially controlled properties
Pleskunov, Pavel ; Shukurov, Andrey (advisor) ; Čech, Vladimír (referee) ; Tichý, Milan (referee)
Title: Multicomponent plasma polymers with spatially controlled properties Author: MSc. Pavel Pleskunov Department / Institute: Department of Macromolecular Physics/Charles University Supervisor of the doctoral thesis: Prof. Ing. Andrey Shukurov, PhD, Department of Macromolecular Physics / Charles University Abstract: Mixing of two (or more) polymers often leads to phase separation and to the formation of nanoscale architecture, which can be highly attractive in various applications including controllable drug delivery, fabrication of separation and solid electrolyte membranes, gas storage, etc. Different wet-chemistry techniques already exist to produce nanophase-separated polymers; however, capturing the resultant polymeric structure in a predictable manner remains a challenging task. In this thesis, a low-temperature plasma-based strategy is investigated for the production of multicomponent thin films of plasma polymers with spatially discriminated nanoscale domains. Gas aggregation cluster source is used for the fabrication of nanoparticles of plasma polymerized acrylic acid, whereas Plasma-Assisted Vapor Phase Deposition is used for the deposition of thin films of poly(ethylene oxide) plasma polymer. Embedding of nanoparticles into matrices of thermodynamically incompatible plasma polymer as well as...
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Silicification of diatoms from a cellular, evolutional and ecological point of view
Šmída, Adam ; Kulichová, Jana (advisor) ; Němcová, Yvonne (referee)
Diatoms are a significant protist group. They've been getting a lot of attention because of their various silica cell walls since their discovery at the end of the 18th century. Even though the mechanism of the morphologically variable cell wall synthesis is well known in terms of shape and ornamentation, only recently it has been enabled to investigate the diatom silicification on the molecular basis. The knowledge of the silica cell wall synthesis can then be used to understand general acpects of biosilica handling and to enlighten the possible evolutionary substance and the progress of this phenomenon. Key words: biomineralisation, diatoms, long chain polyamins, nanostructure, silaffins, silica transporters, silica deposit vesicle, silicification
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Neutron investigation of Nitinol stents and massive samples before and after PIRAC coating
Rogante, M. ; Buhagiar, J. ; Cassar, G. ; Debono, M. ; Lebedev, V. ; Mikula, Pavol ; Ryukhtin, Vasil
Nitinol, a thermoelastic Ni-Ti Shape Memory Alloy (SMA) with approximately 50 at. % Ti, is adopted in a wide range of medical equipment and devices used in interventional radiology, orthopaedics, neurology and cardiology, in particular as a smart material for stents. In this work, NiTi real stents and massive samples before and after different Powder Immersion Reaction Assisted Coating (PIRAC) treatments have been investigated by using two neutron techniques: (1) Small and Ultra-Small Angle Neutron Scattering (SANS, USANS) for nano- and micro-scale characterization, obtaining information on structure and the effects due to the coating treatment, and (2) High-Resolution Neutron Diffraction (HRND), evaluating the macrostrain components resulting from angular shifts of diffraction peaks and the micro-strains in the plastically deformation region by means of profile-broadening analysis. The obtained results contribute: improving knowledge of defects and other key features of the materials complementary to those achieved by using traditional examination techniques. helping to better understand the functional characteristics of Nitinol parts and predict the material's mechanical behaviour.
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Structuring of plasma polymers: new methods for fabrication of nano-architectured thin films
Nikitin, Daniil ; Shukurov, Andrey (advisor) ; Novák, Stanislav (referee) ; Straňák, Vítězslav (referee)
Title: Structuring of plasma polymers: new methods for fabrication of nano-architectured thin films Author: Daniil Nikitin Department / Institute: Department of Macromolecular Physics/Charles University Supervisor of the doctoral thesis: Doc. Ing. Andrey Shukurov, PhD, Department of Macromolecular Physics/Charles University Abstract: The PhD thesis aims at the investigation of nanostructures based on plasma polymers. The main attention is paid to the combination of a gas aggregation cluster source with plasma-assisted vapor phase deposition for the fabrication of metal-polymer nanocomposites with bactericidal potential. Copper nanoparticles were incorporated into a biocompatible matrix of plasma polymerized poly(ethylene oxide) (ppPEO). The efficiency of such nanocomposite against multi-drug resistant bacteria was demonstrated. It was found that the segmental dynamics of the plasma polymer significantly changed in the presence of nanoparticles as revealed by the measurements of the dynamic glass transition temperature. The nanoscale confinement crucially influences the non-fouling properties of poly(ethylene oxide). A separate chapter is dedicated to the examination of the nanoparticle formation, growth and transport inside the source. Copper and silver nanoparticles were detected in situ in the gas phase...
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Temperature drift compensation for nanostructure analysis
Hakira, Stanli ; Páleníček, Michal (referee) ; Bábor, Petr (advisor)
An ultra high vacuum apparatus for nanostructure experiments is being developed by the Tescan company in cooperation with the Institute of Physical Engineering of the Faculty of Mechanical Engineering. The apparatus is designed for preparation, modification, and analysis of nano-scale structures. A sample holder which allows heating and cooling has been developed for the apparatus. A scanning electron microscope is attached to the chamber to provide analytical and manufacturing capabilities. During experiments with heating enabled, the sample moves relative to the SEM column, causing drift of the image. This bachelor thesis proposes a solution to the problem of temperature drift by the means of motion tracking based on image registration using Fourier transform. An application complementary to the SEM control software which implements the algorithm was designed and tested at the instrument.
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Characterisation of dielectric films on a silicon wafer
Fillner, Patrik ; Boušek, Jaroslav (referee) ; Hubálek, Jaromír (advisor)
This bachelor thesis focuses on thin oxide based dielectric layers on silicon wafer. Main effort is for characterization of properties of samples. This technology can be used for manufacturing capacitors on silicon chips. Samples are based on planar oxide layers made with thin film technology on single silicon wafers coated with electrodes deposited by evaporation or by sputtering.
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