Mgr. Ondřej Jašek, Ph.D.
the head of the laboratory
study of microwave plasma, carbon nanostructures and nanomaterials
Department of Plasma Physics and Technology
Microwave and high-frequency plasma laboratory
Our laboratory focuses on the microwave plasma as a versatile platform for the study of plasma instabilities and the synthesis of advanced materials. In our laboratory you can also find apparatuses for preparing thin films using high-frequency discharges. The microwave and high-frequency plasma laboratory is located on the underground floor of building No.2 of the MUNI Faculty of Science campus at Kotlářská 2.
Microwave and high-frequency plasmas are simple, highly efficient, and versatile. We use them to create metal and carbon-based nanomaterials by temperature and pressure-dependent decomposition of organic precursors. Such as metal nanoparticles can further serve as a catalyst for the formation of nanotubes. Further, our laboratory uses high-temperature microwave plasmas to decompose hydrocarbons to synthesize graphene and generate hydrogen for modern power generation. We also use low-temperature, high-frequency discharge plasmas to deposit a wide range of functional layers on different types of surfaces.
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prof. Mgr. Vít Kudrle, Ph.D.
study of microwave plasma and its self-organization
doc. RNDr. Vilma Buršíková, Ph.D.
deposition of thin films (PECVD, PVD), characterization of mechanical properties of thin protective coatings
Mgr. Roman Přibyl
development of technologies for thin film preparation by PECVD and thin film analysis
Microwave plasma diagnostics
Microwave plasmas can be ignited in various conditions, such as pressure, power delivery, or gaseous environments. The plasma is diffuse, filamentary, or a stream, depending on these parameters. The principle of filament excitation, its stability, the relative positions, and the behavior of individual filaments in a mixture of argon and reactive gases is one of the unresolved questions of current plasma physics, which we are investigating. We also investigate the effect of plasma temperature and electron concentration on the synthesis process of nanomaterials in the presence of organic precursors and reactive gas admixtures.
Students
- Jan Kodýtek – Diagnostics of microwave plasma jet
- Tereza Vaněčková – Possibilities of plasma conversion of CO2 and H2O to CH4 under extraterrestrial conditions
Successfully defended final theses
- 2022 disertation thesis – Miroslav Šnírer – Diagnostics and applications of atmospheric pressure microwave plasma
- 2022 disertation thesis – Jan Faltýnek – Microwave diagnostics of plasma and materials
- 2019 bachelor thesis – Kryštof Mrózek – Diagnostics of gliding arc plasma
- 2019 bachelor thesis – Petra Vargová – Diagnostics of pulsed microwave plasma
- 2018 bachelor thesis – Martin Duchaň – Optical and microwave diagnostic of surface wave plasma
- 2018 diploma thesis – Jan Gregor – Study of processes in gliding arc plasma
- 2017 disertation thesis – Lucia Kuthanová – Internally and externally induced non-stationary phenomena in filamentary plasma discharges
- 2016 bachalor thesis – Jan Gregor – Optical diagnostics of gliding arc discharge
- 2014 diploma thesis – Jan Faltýnek – Microwave diagnostics of plasma
- 2013 disertation thesis – Jaroslav Hnilica – Time resolved diagnostics of microwave pulsed plasma
- 2012 diploma thesis – Lucia Kuthanová – Study of surface wave excited plasma source
Publications
- Electron concentration in the non-luminous part of the atmospheric pressure filamentary discharge
J. Faltýnek, V. Kudrle, M. Šnírer, J. Toman and O. Jašek
DOI: 10.1088/1361-6595/abcb6b, 2021 Plasma Sources Sci. Technol. 30 015001 - Stable filamentary structures in atmospheric pressure microwave plasma torch
M. Šnírer, J.Toman, V. Kudrle and O. Jašek
DOI: 10.1088/1361-6595/ac1ee0, 2021, Plasma Sources Sci. Technol. 30 095009 - Structure of microwave plasma-torch discharge during graphene synthesis from ethanol
M. Šnírer, V. Kudrle, J. Toman, O.j Jašek and J. Jurmanová
DOI: 10.1088/1361-6595/abfbea, 2021, Plasma Sources Sci. Technol. 30 065020 - Computational study of plasma-induced flow instabilities in power modulated atmospheric-pressure microwave plasma jet
M. Kubečka, M. Šnírer, A. Obrusník, V. Kudrle and Z. Bonaventura
DOI: 10.1088/1361-6595/ab9b19, 2020, Plasma Sources Sci. Technol. 29 075001 - Numerical enhancements of the microwave resonant cavity method for plasma diagnostics
J. Faltýnek, V. Kudrle, J. Tesař, M. Volfová and A. Tálský
DOI: 10.1088/1361-6595/ab4300, 2019, Plasma Sources Sci. Technol. 28 105007
Carbon nanostructures
Carbon nanostructures as a material are very light and durable, have a large surface area, and good electrical and thermal conductivity. Graphene is a state-of-the-art two-dimensional carbon nanomaterial, consisting of only a single plane of carbon atoms arranged in a hexagonal graphite-like network. Carbon nanostructures can be also found in the form of fullerenes, nanocrystalline particles, nanowires, and nanotubes. Nanotubes also consist of a single atomic layer of carbon atoms, but the entire structure takes the form of single or multiple cylinders embedded in each other.
Carbon nanomaterials are used in the high-strength and tough composites for the manufacturing of tennis rackets, snowboards, cars, airplane fuselage or body of space rockets. The combination of excellent mechanical properties, chemical resistance, and large surface area allows these materials to be employed as membranes for absorbing hazardous substances, separating chemicals, or purifying water. There is also huge potential for these nanostructured materials in the energy production and large-scale production of new batteries and supercapacitors. So far, our carbon nanomaterials, especially few-layer graphene, have been used as hazardous gas sensors or composite materials for electromagnetic absorption. They have excellent electrical conductivity and exceptional resistance to oxidation at high temperatures in comparison to other carbon-based materials. At the same time, high-temperature microwave plasma is also an ideal tool for decomposing organic compounds and generating syngas or hydrogen for modern energy applications.
Successfully defended final theses
- 2023 diploma thesis – David Nejezchleba – Control of structural and chemical composition of graphene as a path towards improvement of its functional properties
- 2022 disertation thesis – Jozef Toman – Microwave plasma synthesis and surface modification of nanostructured materials
- 2019 diploma thesis – Daniel Burda – Study of graphene growth by chemical vapour deposition method
- 2018 diploma thesis – David Němček – Plasma chemical synthesis and functional properties of nanostructured materials
- 2016 bachelor thesis – Daniel Burda – Graphene growth by chemical vapour deposition at atmospheric pressure
- 2016 bachelor thesis – David Němček – Carbon nanotube growth in the presence of water vapour
- 2016 diploma thesis – Jozef Toman – Microwave plasma synthesis of two dimensional carbon nanostructures
- 2014 bachelor thesis – Jozef Toman – Volume synthesis of graphene by microwave plasma torch
- 2014 diploma thesis – Petr Jelínek – Synthesis and properties of graphene
- 2012 bachelor thesis – Petr Jelínek – Methods of making graphene
Publications
- On the gas-phase graphene nanosheet synthesis in atmospheric microwave plasma torch: Upscaling potential and graphene nanosheet‑copper nanocomposite oxidation resistance
J. Toman, M. Šnírer, R. Rincón, O. Jašek, D. Všianský, A.M. Raya, F.J. Morales-Calero, J. Muño and M.D. Calzada
DOI: https://doi.org/10.1016/j.fuproc.2022.107534, Fuel Processing Technology, Volume 239, January 2023, 107534 - Controlled high temperature stability of microwave plasma synthesized graphene nanosheets
O. Jašek, J. Toman, D. Všianský, J. Jurmanová, M. Šnírer, D. Hemzal, A. G. Bannov, J. Hajzler, P. Sťahel and V. Kudrle
DOI: 10.1088/1361-6463/abdb6d, 2021 J. Phys. D: Appl. Phys. 54 165201 - Microwave plasma-based high temperature dehydrogenation of hydrocarbons and alcohols as a single route to highly efficient gas phase synthesis of freestanding graphene
O. Jašek, J. Toman, M. Šnírer, J. Jurmanová, V. Kudrle, J. Michalička, D. Všianský and D. Pavliňák
DOI: 10.1088/1361-6528/ac24c3, 2021 Nanotechnology 32 505608 - On the transition of reaction pathway during microwave plasma gas-phase synthesis of graphene nanosheets: From amorphous to highly crystalline structure
J. Toman, O. Jašek, M. Šnírer, D. Pavliňák, Z. Navrátil, J. Jurmanová, St. Chudják, F. Krčma, V. Kudrle and J. Michalička
DOI: https://doi.org/10.1002/ppap.202100008, 2021, Plasma Processes and Polymers,Volume 18, Issue 8 - Study of graphene layer growth on dielectric substrate in microwave plasma torch at atmospheric pressure
O. Jašek, J. Toman, J. Jurmanová, M. Šnírer, V. Kudrle, V. Buršíková
DOI: https://doi.org/10.1016/j.diamond.2020.107798, 2020, Diamond and Related Materials, Volume 105, 107798 - On the interplay between plasma discharge instability and formation of free-standing graphene nanosheets in a dual-channel microwave plasma torch at atmospheric pressure
J. Toman, O. Jašek, M. Šnírer, V. Kudrle and J. Jurmanová
DOI: 10.1088/1361-6463/ab0f69, 2019, J. Phys. D: Appl. Phys. 52 265205
Nanoparticles
Nanoparticles are very small in size, diameter of 100 nm or less. We can create them in many ways and forms. Microwave plasma synthesis of nanoparticles uses high-temperature decomposition of organic precursors and subsequent formation of nanoparticles with the desired physical and chemical properties. In the past years, our laboratory has been involved, in the preparation of magnetic nanoparticles with precise phase structures, which have been tested in fields such as magnetic resonance and cell therapy, ferrofluids, or photoelectrochemical water decomposition.
Successfully defended final theses
- 2016 bakalářská práce – Branislav Hesko – Plasmachemical syntheis of magnetic nanoparticles
- 2013 bakalářská práce – Miroslav Šnírer – Spectroscopy during plasma synthesis of nanomaterials
- 2013 diplomová práce – Peter Zelina – Magnetic nanoparticles: production and applications
- 2012 bakalářská práce – David Vašíček – Synthesis of iron nanoparticles with advanced magnetic properties
- 2010 bakalářská práce – Peter Zelina – Plasma synthesis of nanoparticles in low-pressure discharge
- 2010 bakalářská práce – Hana Jirků – Plasma synthesis of nanoparticles in torch discharge
Publications
- The Effect of Uncoated SPIONs on hiPSC-Differentiated Endothelial Cells
B. Šalingová, P. Šimara, P. Matula, L. Zajíčková, P. Synek, O. Jašek, L. Veverková, M. Sedláčková, Z. Nichtová and I. Koutná
DOI: 10.3390/ijms20143536, Int. J. Mol. Sci. 2019, 20(14), 3536
High-frequency discharges
There are two thin film deposition devices in our laboratory, GEC (Gaseous Electronic Cell) reactor and a reactor for large-scale thin film deposition. Both reactors are used for investigation of thin film depositions as well as plasma diagnostics.
The large-capacity reactor, called R4, is used for large-scale thin film deposition by the PECVD method. The R4 reactor was developed as a working sample in the framework of research supported by the TAČR project NCK TN01000038/17, National Centre of Competence for Materials, Advanced Technologies, Coatings and their Applications. Inside the reactor, there is a powered and a grounded electrode. The limiting pressure of the apparatus is 10-4 Pa. DC and RF sources of 13,56 MHz and 27,12 MHz can be used. The power delivered to the plasma is 0 - 600 W.
Plasma enhanced chemical vapor deposition (PECVD) is a widely used technique for thin film deposition. This method uses the energy from the plasma to split the bonds of the so-called precursor and carrier gas. These two substances then react in the reactor volume and on the reactor walls/electrodes to form a thin film. Thin films improve the surface properties of bulk materials. For example, the surface energy (wettability) and electrical, optical, and thermal properties can be enhanced while maintaining the bulk properties of the supported object. For example, protective hard diamond-like layers (DLC) are deposited on the device.