Topics of PhD. (new 2017)

Proposed themes for 2017-2018

Development and efficient implementation of fully relativistic methods for calculation of response properties of heavy elements containing paramagnetic systems.
Supervisor: Dr. Oľga Malkina, DrSc. (Department of theoretical chemistry)

  • Nowadays, the study of heavy-element containing paramagnetic systems is becoming more important in various scientific areas. For instance: a) in the development of advanced magnetic materials for data storage, b) in decreasing the radio toxicity and heat load of nuclear spent fuel, c) in the development of new organic light-emitting diodes (OLEDs). The main goal of the thesis is the development of new relativistic methods for calculation of spectroscopic parameters (such as nuclear magnetic resonance) of paramagnetic systems, followed by their efficient implementation into program package ReSpect (www.respectprogram.org). This requires skills from both relativistic quantum physics and computational science. An optional goal is to apply the newly implemented methods to relevant systems in close collaborations with our foreign partners from Germany, Norway, Austria or Czech Republic.

Development of methods for synthesis of ternary fluorides for modern applications.
Supervisor: doc. Ing. Miroslav Boča, DrSc. (Department of molten systems)

  • The analysis of fluorides melts requires knowledge of the phases present. Analysed mixtures often consist of more than one phase that cannot be separated. Thus it is necessary to prepare these phases in pure form. The application of common methods, however, often fails. The object of the work will be the development of new methods for the synthesis of inorganic fluorides, or suitable modification of existing methods.

Molten systems in solar applications
Supervisors: doc. Ing. Miroslav Boča, DrSc., Ing. Viliam Pavlík, PhD. (Department of molten systems)

  • The student will be dealing with simplified input/output thermodynamic calculations used for thermal storage proposal, including suggestions of salts and materials of storage.

Corrosion of superalloys for energy applications
Supervisor: doc. Ing. Miroslav Boča, DrSc., Ing. Viliam Pavlík, PhD. (Department of molten systems)

  • The focus of the work will be on corrosion resistance of a high-temperature alloy, including measurements of the surface, microgeometry, thickness of the corrosion layer, aggressiveness of the environment and gravimetry of the samples.

The solid electrolytes on the basis of fluoride complexes
Supervisor: Ing. František Šimko, PhD. (Department of molten systems)

  • The topic deals with the preparation of inorganic fluoride complexes with alkaline cations which can be used as solid electrolytes with high conductivity. Thermodynamic, thermochemical, spectral and structural characterisation of the complexes will be performed, as well as how its properties change with temperature. Synergy between data from classical and modern techniques is expected.

Energy future in inorganic melts. Macro and micro characteristics of selected fluoride systems
Supervisor: Ing. Blanka Kubíková, PhD. (Department of molten systems)

  • Molten salts have a wide range of industrial uses in such different areas as applications connected with fuel and cooling systems and heat exchange circuits of nuclear reactors, pyrochemical separation of spent nuclear fuel, and electrochemical deposition of metals. However, any application of a molten salt requires its basic physico-chemical properties to be known over a wide concentration and temperature range. Therefore the object of this work will be the analysis of selected fluoride molten salt systems based on transition d- or f- elements regarding phase equilibrium, volume, surface and transport properties.

Phase equlibrium, electrochemical and physico-chemical characteristics of fluoride melts for electrodeposition of rare earth metals and other metals declared by European Commission as critical materials
Supervisor: Ing. Michal Korenko, PhD. (Department of molten systems)

  • The Rare Earth Metals (along with certain other materials, like Mg, Ti, etc.) have been declared to be critical for EU economies by the European Commission.  The reason for the selection of these materials is Chinese dominance, and in some cases, even a global monopoly in their production.  For the EU, these materials have both a high supply risk and high demand for recycling. One way to develop a recycling pathway is to commercialize high-temperature electrowinning of these metals from molten fluorides.  The main focus of the project will thus be on the identification of suitable systems, their electrochemical analysis (kinetic and diffusion parameters), and also the investigation of their physico-chemical properties (phase equilibria, transport properties, volume properties and surface properties).

Fluorescence nanofilms with cyanine dyes and clay minerals
Supervisor: Mgr. Adriana Czímerová, PhD. (Department of hydrosilicates)

  • Cyanine dyes represent a group of dyes that have been extensively studied for decades. Due to their structural and chemical variability, ability to form fluorescence aggregates, and different possibilities for interaction with other molecules, these dyes offer a wide range of practical applications. The topic of this study is the preparation of thin layers using various preparation technics. The hybrid nanosystems in this study consist of an inert inorganic matrix – mainly of clay minerals – and adsorbed cyanine dyes. Nanofilms will be prepared and studied using absorption spectroscopy in the UV/VIS and near-infrared regions. In this context, particular attention will be paid to the orientation of cyanine dyes inside the structure of the clay minerals and calculation of the thickness of the prepared films. However, the main focus of the study will be the characterization of the prepared thin layers by means of fluorescence spectroscopy.

Quantum dots as a light harvesting antennas
Supervisor: Mgr. Adriana Czímerová, PhD. (Department of hydrosilicates)

  • The integration of inorganic and organic molecules on the nanoscale range opens the door to the study of novel and promising nanomaterials. This work will be focused on the preparation of various types of quantum dots, followed by study of energy transfer between the prepared quantum dots and dye molecules. In such systems, quantum dots can play the role of light-harvesting antennas. The most important part of the work will be the preparation of quantum dots and optimization of the conditions for an efficient energy transfer process. The prepared systems will then be investigated using absorption spectroscopy in the UV/VIS and near-infrared region. The optical and photophysical properties will be studied in detail by means of fluorescence spectroscopy.

Application of organo-modified layered hydrosilicates for the synthesis of functional materials.
Supervisor: Ing. Helena Pálková, PhD. (Department of hydrosilicates)

  • Modification of clay minerals (layered silicates) using different types of organic compounds will be the main topic of the PhD. At present, Presently, this subject is drawing attention due to the alteration of the properties of the clay minerals, which widens the possibilities for their application. A wide spectrum of organic species (including organic cations, cationic polymers, non-ionic compounds, and organosilanes) have been applied for this purpose. The resulting materials may display new properties, e.g. improved efficiency in adsorption processes and catalytic reactions, or acting as a support on which metal nanoparticles may be immobilized. The aim of this work will be optimization of the modification process and understanding of the mechanism of the interactions between the inorganic component and the selected organic species in the prepared systems. The suitability of the systems as supports for metal nanoparticles will be investigated.

Study of clay minerals and their intercalates by means of computational methods.
Supervisor: Ing. Eva Scholtzová, CSc. (Department of theoretical chemistry)

  • Clay minerals and their intercalates are widely used in industry and have therefore become the subject of study by both experimentalists and theoreticians. The use of theoretical computational methods can help to obtain new information about the arrangement of the intercalated molecules and cations, and also about the vibrational spectra of these compounds. The calculated values will be compared with experimentally-obtained data.

Oxynitride-based transparent luminescent materials
Supervisor: doc. Ing. Zoltán Lenčéš, PhD. (Department of ceramics)

  • The work will be focused on the cost effective preparation of oxynitride (MgAlON and SiAlON)-based phosphors from a mixture of oxides and nitrides and/or from siloxane- and polysilazane-based polymer precursors. The composition of the starting powder mixtures, the nitridation conditions, and the high-temperature annealing of the phosphors will be optimized. The main goal of the work will be the preparation of high-intensity green and red phosphors, which can be used for the construction of warm white-light-emitting diodes (LEDs). The prepared materials will also be tested for applications in photovoltaics, especially for solar spectral conversion, i.e. for the conversion of UV, NUV and violet light to a wavelength which can be absorbed by a silicon-based photovoltaic device.

Effect of Si3N4 microspheres addition on mechanical and biological properties of bone cements based on brushite
Supervisor: doc. Ing. Miroslav Hnatko, PhD. (Department of ceramics)

  • The proposed work will focus on the preparation and characterization of composite cements based on calcium phosphate with the addition of a strengthening phase in the form of silicon nitride-based microspheres. Porous Si3N4 microspheres with varying of Ca3(PO4)2 content will be prepared by flame synthesis. The effect of Si3N4 microspheres as fillers will be studied. In addition to a strengthening of the calcium phosphate cement (quantity effect, size effect, structure etc.), a change is also expected in the biological properties (biotoxicity and antibacterial effect of Si3N4, resorption rate, etc.).

Assessment of secondary raw materials for the preparation of materials used in extreme conditions.
Supervisor: Ing. Jaroslav Sedláček, PhD. (Department of ceramics)

  • The subject of the proposed study will be the timely topic of waste recovery, with the potential use of wastes as secondary raw material sources for the preparation of ceramic materials for extreme conditions (high temperatures, mechanical stress, corrosive environments, etc.). The main objective is obtaining ceramic materials and/or composites based on nitrides, oxynitrides, carbides and oxide materials such as SiO2-Al2O3-CaO-MgO-MexOy from existing sources of secondary raw materials generated by the production of ferroalloys, nickel, or magnesite, the combustion of solid fuels or municipal waste, mining processes, etc. The results will provide information on the application potential of secondary raw materials for production of more valuable advanced materials. The planned study will involve the characterization of raw materials, their treatment and thermodynamic analysis, optimization of the process of treatment (carbothermal reduction, nitridation, etc.) and sintering, and the evaluation of the properties of the materials. In cooperation with Slovak industrial partners, the potential possibilities will be discussed for extension of existing technologies in terms of the direct processing or recovery of waste streams to yield advanced ceramics, thus significantly reducing environmental and energy demands.

Development of advanced ceramic materials with the improved resistance to extreme environments for aerospace industry.
Supervisor: Ing. Peter Tatarko, PhD. (Department of ceramics)

  • The use of a new type of additives (such as rare-earth elements), combined with the use of new processing routes (such as utilisation of polymer-based ceramic precursors), and modern sintering techniques (such as „rapid hot pressing“), opens up the possibility of developing new ultra-high temperature materials with desirable microstructural and chemical composition and potentially improved properties in extreme environments. This very timely, multidisciplinary project brings together fundamental research with commercial potential for aerospace applications. The main aim is to develop ceramic materials and their composites, based on borides and carbides of metal transition metal compounds (Hf, Zr, Ta), with significantly improved ultrahigh temperature properties and long-term thermo-chemical resistance. This will significantly improve the current state of the art, as well as yielding improved lifetime and reliability on the part of these newly-developed materials. This will fulfil the commercial potential of these materials for application as thermal protection systems for hypersonic and atmospheric re-entry vehicles, as well as use in different components of the propulsion systems. Development of the materials will consist of the preparation of chemically-pure ceramic powder mixtures and polymer-based ceramic precursors, and their subsequent forming, densifying and sintering. The investigation of the sintering mechanisms as well as the formation of chemical phases in the materials during sintering and their in-situ formation in extreme environments will also be investigated. The mechanical and thermo-chemical properties of these materials will be investigated in laboratory conditions, as well as by simulating the real re-entry conditions for potential industrial partners.