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Gel polymer electrolytes with fire retardands
Veselkova, Iuliia ; Jahn, Michal (referee) ; Sedlaříková, Marie (advisor)
This graduate work deals with the study and preparation of gel polymer electrolytes with flame retardants for lithium-ion batteries. The theoretical part describes the types of electrolytes, their features, benefits, how they differ and where they are used in detail. The basis of this section is gel electrolytes with flame retardants, to measure their electrical and electrochemical properties. The experimental part deals with the preparation of samples of gel electrolytes with different percentages of flame retardant, where varied species of flame retardants and measuring their electrical conductivity and potential windows. Impedance spectroscopy, cyclic voltammetry and dynamic-analytical thermal analysis were selected as measuring methods.
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Methodology of Determination of Electroinsulating Properties
Čanigová, Veronika ; Nevřivová, Lenka (referee) ; Sokolář, Radomír (advisor)
The core of this bachelor thesis is porcelain and electrical porcelain property specification accompanied by definition and explanation of electric conductivity. The theoretical section provides insight into electrical porcelain production from initial raw material exploitation to final stages of body baking. The experimental part compiles a number of electrical porcelain test methods based on current European standards and draft test procedures, which are followed in order to specify properties of conventional electrical porcelain as well as emerging anorthite porcelain based on aluminate cement.
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Silicate materials with enhanced electrical conductivity
Míková, Maria ; Kusák, Ivo (referee) ; Rovnaník, Pavel (advisor)
This bachelor thesis deals with electrical properties of cement- or aluminosilicate-based materials used in building industry. It presents the summary of the most commonly used functional fillers with ability to increase conduction of the composites and theirs characteristics. Thesis also deals with measured electrical properties and applications of composites with enhanced electrical conductivity. In the experimental part, the influence of graphite powder concentration on the characteristics of alkali activated slag was examined. Electrical, mechanical properties and microstructure was observed. Microstructure was examined by means of mercury porosimetry and scanning elektron microscopy.
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Monitoring properties of nanocomposites on base epoxy
Libra, Miroslav ; Rozsívalová, Zdenka (referee) ; Polsterová, Helena (advisor)
The present thesis deals with the study of nanotechnology in the field of composite materials (nanocomposites). Furthermore, the production, composition and electrical properties of these materials. Samples for the experiment are made of epoxy resin as matrix and titanium dioxide TiO2 as fillers with different benefits. Are the measurements the temperature dependence of permittivity, loss factor and internal resistivity.
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Mechanical and Electrical Properties of Thin Metal Films Deposited by Vacuum Evaporation
W. F. Yahya, Doaa ; Kolařík, Vladimír (referee) ; Štencl,, Jiří (referee) ; Šandera, Josef (advisor)
Thin layers are widely used in many fields of technology and today we can say that they are found in all modern technologies. Thin layers can be created in two ways, namely by chemical or physical means. This work focuses on the latter method, more particularly a technology of thermal evaporation of thin layers in a vacuum. The work focuses on the process principles during and after the evaporation. Much of the work focuses on the development and design of experiments. These experiments illustrate some of the phenomena that take place on thin films produced by the aforementioned technology. Work helps to better understand processes during formation of thin layers and properties that influence the quality and stability of thin films. In conclusion we describe results of experiments and new developments in the field of thin films deposition using evaporation under vakuum are summarized.
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Dielectric Properties of Thin Tantalum and Niobium Oxide Layers
Abuetwirat, Inas Faisel ; Chobola, Zdeněk (referee) ; Lelák, Jaroslav (referee) ; Liedermann, Karel (advisor)
Dielektrická relaxační spektroskopie je jednou z užitečných metod pro studium molekulární dynamiky materiálů. Díky nedávnému pokroku v přístrojové a měřicí technice je dnes možné získat dielektrické spektrum v širokém frekvenčním intervalu a pro velice rozdílné materiály. Cílem mé práce bylo studium dielektrických relaxačních spekter a vodivosti oxidů titanu, niobu, tantalu, lanthanu a hafnia pro katody pracující na principu studené emise. Cílem výzkumu bylo analyzovat frekvenční a teplotní chování těchto oxidů, včetně jejich vodivosti, v širokém frekvenčním a teplotním rozsahu, a pokusit se stanovit původ relaxačního mechanismu. Vzhledem k tomu, že původně zadaný rozsah oxidů byl dosti široký, soustředila se pozornost pouze na oxidy tantalu a niobu, rovněž s ohledem na jejich aplikace v elektrolytických kondenzátorech. Elektrické, tepelné a mechanické (při zpracování) vlastnosti oxidů tantalu a niobu jsou dnes již dobře prozkoumány. K dispozici je však jen málo poznatků o jejich dielektrických relaxačních mechanismech. Výsledky získané pro Ta2O5 ukazují existence relaxačního maxima, nacházejícího se v experimentálně dostupném teplotním a frekvenčním intervalu 187 K – 385 K a 1 Hz – 10 MHz. Frekvence ztrátového maxima se řídí Arrheniovým zákonem s aktivační energií 0.048 eV. Ve vodivostních spektrech vykazují tenké vrstvy Ta2O5 na nízkých frekvencích ustálenou hodnotu a při vysokých frekvencích monotónní nárůst, který závisí na teplotě. Pozorovanou vodivost lze popsat mocninnou funkcí s exponentem nepatrně větším než jedna (tzv. superlineární závislost). Výsledky získané pro Nb2O5 v podobné teplotní a frekvenční oblasti, 218 K – 373 K, 1 Hz – 1 MHz rovněž ukazují jedno relaxační maximum. Frekvence ztrátového maxima se opět řídí Arrheniovým zákonem s poněkud vyšší aktivační energií 0.055 eV. Niobové kondenzátory vykazují vodivostní mechanismus shodný s kondenzátory tantalovými.
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Mechanical properties of gel polymer electrolytes
Bárta, Vladimír ; Vondrák, Jiří (referee) ; Sedlaříková, Marie (advisor)
This work deals with the measurement of electrical conductivity and mechanical properties of gel polymer electrolyte containing Lithium ion. Their preparation and performance depends on the concentration of nanoparticles Al2O3 contained therein. The theoretical part deals with the development of gel polymer electrolyte, their use and methods of measurement of electrical conductivity and mechanical properties. In the experimental part describes the preparation of gel electrolyte, the measurement of electrical conductivity, temperature dependence and the measurement of mechanical properties.
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Properties of aprotic electrolytes for lithium-ion accumulators
Staněk, Vladimír ; Máca, Josef (referee) ; Frk, Martin (advisor)
The present work deals with the properties of suitable electrolytes for lithium-ion batteries. The first part described in the current issue of electrolytes for lithium-ion batteries, types of solvents and their properties and methods of measurement properties. The second part is devoted to the measurement of the properties of solvents and electrolytes such as relative permittivity, density and viscosity. Measurement of relative permittivity was focused on the measurement of the solvent mixture with varying the percentage of the solvent. Viscosity and density were measured on a solvent with a lithium salt added (final electrolyte).
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Dielectric properties of liquid insulators
Jahn, Michal ; Starý, Jiří (referee) ; Špinka, Jiří (advisor)
This master‘s thesis deals with measurement of liquid dielectric materials (insulators). Above all, it is the different kinds of clean and drinking water, but also transformer oils. There was done theoretical information retrieval about the given topic in this project and on the basis of theory there were realized the relevant measurements of selected properties of liquid dielectric, such as permittivity, capacitance, loss number, conductivity, but also temperature dependence of these parameters. The measurements were realized with the help of product manufactured at the faculty FEKT VUT and with the help of measuring system AGILENT 16452A. The measured results were evaluated, graphically processed and compared.
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