The diploma thesis is focused on the preparation of test samples of paint-filled micronized mica and analysis of electrical properties of insulating material values in different environmental conditions. For this purpose, it was created five sets of composite paint primers with different ratio of mica. Samples were gradually exposed to the environment relative humidity of 0%, 33%, 55%, 65% and 75%. For each environment with a defined moisture characteristics were observed in samples exposed to the temperature of 20 to 50 ° C. The diploma paper analyzed the influence of the mass implementation of mica in each set of samples and placed on the surface structure of samples.

A literature review on the topic of ferroic and multiferroic solid solutions of BaTiO3, SrTiO3 and EuTiO3 forms the first part of this master thesis. The second part describes the experimental preparation and evaluation of the properties of samples of europium strontium titanates - EuxSr1-xTiO3. First, the high temperature solid state synthesis was carried out and relative density and open porosity of the sintered samples were evaluated. The sintered samples showed open porosity higher than 10%. The reasons for this behavior were evaluated and described from the point of view of experimental conditions and thermodynamical calculations. Finally, electric and dielectric properties of selected samples were measured. These results show that these samples are insulators and their residual conductivity is caused probably by oxygen vacancies, arising from the synthesis in a strongly reducing atmosphere of pure hydrogen.

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.

This work deals with issues of elecroinsulating varnish and composite materials. The general aim is to observe impact of fulfilment and size of particle against measured values.

The subject of this thesis are composite materials, measuring of their dielectric qualities, particularly of the polyamide and the polyamide filled with various weight percentage of the ground mica. The essential intent of the thesis is to determine the measuring methodology and respective measurement of the basic dielectrical quantities of materials, as are loss factor and the complex permitivity components. The measuring should be done for various temperature and humidity combinations. The thesic contains the physical explanation of measured dependences.

This work deals with issues of dielectric composite materials. The general aim is to observe how the amout of nanofilling influence dielectric spectrum in dependence on relative humidity and temperature which is measured on prepared samples. For this purpose had been created variety of a samples of electroinsulating varnish with different percentage of filling with nanoparticles. Experimental material is epoxy resin NH91 LV filled by Al2O3 nanoparticles.

This work deals with issues of composite materials. The general aim is to observe how the amout of filling infuence dielectric spectrum which is measured on prepared samples. For this purpose had been created variety of a samples with different percentage of filling with mica. Measured values had been compared with theoretically values, determinated using mixture formulas.

The bachelor thesis submitted deals with properties of electro-insulating lacquer hardenable by ultraviolent radiation and temperature. Within the theoretical part a summary of electro-insulating lacquers used in electrotechnics has been elaborated. Chemical changes that take place in this material group have been described during hardening process. A method of dielectric relaxation spectroscopy specifically focused on mathematic and physical description of polarisation and conductive mechanisms taking place in the structure of the given material has been closely studied. In the experimental part a workplace for hardening and long-term exposition of lacquered samples during simultaneous effect of various climatic elements has been designed and built. The selected electric and mechanical properties have been monitored on three sets of experimental samples prepared by means of different methodical procedures. The results gained have been mathematically evaluated and physically interpreted in term of methodical procedure of hardening and different temperature of measurement.

ABSTRAKT Obsah této práce je směřován na řešení problematiky měření impedančních charakteristik dielektrických materiálů, zejména keramik, za pomocí simulace připojení elektrod na mě- řený vzorek. V práci je popsáno měření impedancí se zaměřením na metodu impedanční spektroskopie. Cílem práce je seznámení s problematikou měření komplexní impedance a popsání parazitních jevů, vyskytujících se v materiálu. Dále jsou v práci popisovány současné možnosti simulací a simulačních softwarů jako je zejména ANSYS Maxwell. S využitím simulací tohoto softwaru jsou v práci řešeny impedanční charakteristiky vodivé keramiky a jejich závislost na poloze napájecích elektrod. KLÍČOVÁ SLOVA Dielektrické materiály, elektrická polarizace, impedanční spektroskopie, komplexní impe- dance, vodivé keramiky, ANSYS, metoda konečných prvků. ABSTRACT Content of this thesis is aimed to solutions of issues, created due measurement impe- dance characteristics of dielectric materials, mainly ceramics, using simulation electrode position by specific software. In thesis is described impedance measurement with focusing to impedance spectroscopy. Goal of this thesis is to get acquainted with issues of mea- surement complex impedance and explain parasitics effects in ceramics material. Further goals of thesis are described current possibilities of simulation software ANSYS Ma- xwell. Using this simulation software was solved impedance characteristics of conductive ceramics and their dependence of electrodes position.

This thesis is devoted to an experimental study of dielectric properties of incipient fer- roelectrics. The terahertz time-domain spectroscopy was used to investigate the complex permittivity spectra in both single crystals and various strained thin film structures versus temperature and applied electric bias. Namely, it allowed characterizing the ferroelectric soft-mode dynamics and its coupling to a central mode. An electric-field tunability of bulk single crystals of SrTiO3 was determined up to room temperature for the first time. The phenomenon is governed by soft-mode stiffening under applied field. As an application we proposed and characterized a tunable one-dimensional photonic structure with a thin SrTiO3 plate inserted as a defect layer. The importance of the soft-mode dynamics was stressed also in the study of bulk high density KTaO3 ceramics. A systematic study was performed of a KTaO3 thin film and especially of a set of strained multilayers consisting of SrTiO3/DyScO3 bilayers grown on DyScO3 substrate. Strain-induced ferroelectric transition was observed in these films governed by the soft mode coupled to a lower-frequency relaxation. A general model was developed describing the whole family of the studied samples. Effect of the composition stoichiometry of SrTiO3 films grown on DyScO3 was...