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Abstract

Dielectric materials, used to control and store charges and electric energy, play a key role in
modern electronics and electric power systems. Dielectric spectroscopy is a versatile method,
well-suited for detection, separation and characterization of various contributions to dielectric
response of advanced ceramic and polymeric materials, as it enables understanding of
the behaviour of interfaces at the boundary of two different materials or material phases and
accurate control of material properties. This doctoral dissertation presents the recent studies
conducted in advanced ceramic and polymeric systems by means of dielectric spectroscopy.
In the beginning, a brief overview of theoretical background, analysis and used experimental
techniques of dielectric spectroscopy is presented. Then, the first main focus of
the dissertation is set on CaCu3Ti4O12 ceramic thin films. First, the dielectric response of
core-shell structured ceramic material is modelled in terms of an equivalent electric circuit
with elements that describe distinctive contributions of grains and grain boundaries. Then,
the results of investigations of the influence of preparation conditions on dielectric properties
of CaCu3Ti4O12 thin films are presented: It is shown that by proper post-annealing
process a high dielectric constant of ∼ 3000 can be obtained in films with thickness below
600 nm. Afterwards, the main focus of the dissertation shifts towards advanced polymeric
materials. Firstly, the results of studies of dielectric properties of distinctive dynamic
processes in a new class of relaxor polymers, the relaxor reduced poly(vinylidene fluoridetrifluoroethylene)
copolymer system, are presented and are then used in studies of changes in
dynamic processes of organic and inorganic relaxors due to a dc bias electric field. Secondly,
the structural, caloric, and dielectric properties in blends of relaxor poly(vinylidene fluoridetrifluoroethylene-
chlorofluoroethylene) terpolymer with a small amount of poly(vinylidene
fluoride-chlorotrifluoroethylene) copolymer, developed on aluminum foil, are presented. In
the end, the dielectric response of relaxor polymer systems, in which two different dynamic
processes take place and superimpose in the detected dielectric response, is modelled.
Scientific work, presented in this dissertation, was conducted at the Dielectric Spectroscopy
Laboratory of the Condensed Matter Physics Department of the Jožef Stefan
Institute. The work on CaCu3Ti4O12 ceramic thin films has been done in collaboration
between the Condensed Matter Physics Department, F5, and the Electronic Ceramics Department,
K5, of the Jožef Stefan Institute. Investigations of the reduced P(VDF-TrFE)
copolymer and the terpolymer-copolymer blends have been done in collaboration with the
groups of Prof. Dr. Qun-Dong Shen from the Nanjing University in China and of Prof. Dr.
Horst Beige from the Martin Luther University in Halle, Germany.
This doctoral dissertation, scientific accomplishments of which have been published in
eight articles in peer-reviewed scientific journals, presents the dielectric spectroscopy as a
powerful tool for investigations of both basic and applicatory-oriented properties of various
organic and inorganic materials. This is anticipated to result in their optimization or even
in the synthesis of new materials for advanced applications.