Number of found documents: 567
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Plasma hydrogenation of hydrothermally grown ZnO micropods
Remeš, Zdeněk; Aubrechtová Dragounová, Kateřina; Mičová, J.
2021 - English
The hydrothermally grown ZnO micropods have been placed on grounded stainless-steel holder and exposed to an inductively coupled plasma (ICP) monitored in-situ by optical emission spectroscopy (OES). OES shows the immediate release of oxygen during Ar ion bombardment. The prolonged exposure to hydrogen plasma leads to deterioration of the optical properties as well. The exposure, rf power and hydrogen pressure have been optimized to enhance UV-photoluminescence peak at the wavelength 384 nm related to surface bounded excitons and reduce the defect-related photoluminescence in red spectral range. The strong UV photoluminescence appears just after 1 minute of plasma hydrogenation in a radio frequency plasma discharge with power density 40 W/dm3 and hydrogen pressure 17 Pa. Keywords: ZnO; micropods; inductively coupled plasma; optical emission spectroscopy; photoluminescence spectroscopy; Raman spectroscopy; infrared absorption spectroscopy Available at various institutes of the ASCR
Plasma hydrogenation of hydrothermally grown ZnO micropods

The hydrothermally grown ZnO micropods have been placed on grounded stainless-steel holder and exposed to an inductively coupled plasma (ICP) monitored in-situ by optical emission spectroscopy (OES). ...

Remeš, Zdeněk; Aubrechtová Dragounová, Kateřina; Mičová, J.
Fyzikální ústav, 2021

Growth and properties of diamond films prepared on 4-inch substrates by cavity plasma systems
Babčenko, Oleg; Potocký, Štěpán; Aubrechtová Dragounová, Kateřina; Szabó, Ondrej; Bergonzo, P.; Rezek, B.; Kromka, Alexander
2021 - English
We compare two microwave (2.45 GHz) plasma systems with ellipsoidal and multimode clamshell cavity for diamond synthesis by chemical vapor deposition. We use H2/CH4/CO2 gas mixture for diamond film deposition on Si <100> wafers. Both systems are capable of high pressure (up to 20 kPa) operation and high growth rates (several µm/h). We compare the cavity systems from the point of diamond quality (Raman shift measurement), substrate size (2” versus 4”) and grown film homogeneity together with surface morphology (SEM), deposition rate and parasitic doping levels (photoluminescence). Keywords: large area diamond; microwave cavity plasma; high-power density plasma Available at various institutes of the ASCR
Growth and properties of diamond films prepared on 4-inch substrates by cavity plasma systems

We compare two microwave (2.45 GHz) plasma systems with ellipsoidal and multimode clamshell cavity for diamond synthesis by chemical vapor deposition. We use H2/CH4/CO2 gas mixture for diamond film ...

Babčenko, Oleg; Potocký, Štěpán; Aubrechtová Dragounová, Kateřina; Szabó, Ondrej; Bergonzo, P.; Rezek, B.; Kromka, Alexander
Fyzikální ústav, 2021

CrystalCMP: examples of use
Rohlíček, Jan
2020 - English
The program CrystalCMP can be used for comparison of crystal structures containing separated molecular objects as it is, for instance, in molecular crystals or some metal-organic compounds. The program can be useful in many different situations. This article shows the use of the program CrystalCMP on three basic exam ples for which the program was primarily intended. Keywords: molecular packing; comparison; similarity Available at various institutes of the ASCR
CrystalCMP: examples of use

The program CrystalCMP can be used for comparison of crystal structures containing separated molecular objects as it is, for instance, in molecular crystals or some metal-organic compounds. The ...

Rohlíček, Jan
Fyzikální ústav, 2020

Nanopowders of R.sub.2./sub.Fe.sub.14./sub.B-type compounds in high magnetic fields: The effects of substitutional and interstitial atoms on inter-sublattice exchange interaction
Paukov, M.; Ivanov, L.; Tereshina, I.; Tereshina-Chitrova, Evgenia; Gorbunov, D.; Andreev, A. V.; Pyatakov, A.P.; Granovsky, S.A.; Doerr, M.; Drulis, H.
2020 - English
The fundamental magnetic characteristics of R2Fe14B intermetallics are highly sensitive to atomic substitutions and interstitial absorption of light elements. In this work, both were combined, and the influence of the substitutions in the R-sublattice and hydrogen absorption on the magnetization of (RR’) 2Fe14BHx (R is Tm or Er, and R’ is Nd) in magnetic fields up to 58 T was studied. By using direct hydrogen absorption, (R0.5Nd0.5)2Fe14BHx compounds were obtained with hydrogen content 0≤x≤5.5. Magnetic measurements were carried out on nanopowders. The strength of the inter-sublattice coupling in (R0.5Nd0.5)2Fe14B and their hydrides is estimated by analysing high-field magnetization data. It is shown that hydrogenation weakens the inter-sublattice exchange interaction up to 45 %. Keywords: rare earth; intermetallics; powder metallurgy; magnetism in solids; hydride properties Available at various institutes of the ASCR
Nanopowders of R.sub.2./sub.Fe.sub.14./sub.B-type compounds in high magnetic fields: The effects of substitutional and interstitial atoms on inter-sublattice exchange interaction

The fundamental magnetic characteristics of R2Fe14B intermetallics are highly sensitive to atomic substitutions and interstitial absorption of light elements. In this work, both were combined, and the ...

Paukov, M.; Ivanov, L.; Tereshina, I.; Tereshina-Chitrova, Evgenia; Gorbunov, D.; Andreev, A. V.; Pyatakov, A.P.; Granovsky, S.A.; Doerr, M.; Drulis, H.
Fyzikální ústav, 2020

Nanosecond laser damage of metallic mirrors
Muresan, Mihai-George; Pilná, Kateřina; Čech, Pavel; Mydlář, Martin; Vanda, Jan; Navrátil, Petr
2020 - English
Laser surface processing is an established method to introduce surface functionalities on solid surfaces with the required throughputs for a commercial process. Fabrication of laser induced surface structures in an effective matter is done by laser interaction studies, which reveal the best processing parameters (laser wavelength, fluence, repetition, together with the processing speed and environment). Customized solutions are providing the best yields and they are being implemented faster than ever. However, the optics manufacturers are not being to keep up the pace with the new requirements, so they turn instead on older, but safer technology. In order to get a better understanding of optics capabilities, thorough testing is required. Common laser metallic mirrors, commercially available, are being rigorously tested using a nanosecond Yb:YAG laser and the results are compared with the vendor’s information.\n Keywords: laser patterning; metallic mirrors; LIDT; nanosecond laser testing Available at various institutes of the ASCR
Nanosecond laser damage of metallic mirrors

Laser surface processing is an established method to introduce surface functionalities on solid surfaces with the required throughputs for a commercial process. Fabrication of laser induced surface ...

Muresan, Mihai-George; Pilná, Kateřina; Čech, Pavel; Mydlář, Martin; Vanda, Jan; Navrátil, Petr
Fyzikální ústav, 2020

Studium vlivu složení ve směsi CsCl-HfCl.sub.4./sub. na její tepelné vlastnosti v uzavřeném systému pomocí DSC analýzy
Král, Robert; Zemenová, Petra; Vaněček, Vojtěch; Bystřický, Aleš
2020 - Czech
Příspěvek se zabývá studiem tepelného chování směsi CsCl-HfCl4 o různém složení (nadbytek Cs- nebo Hf-složky) v uzavřeném systému (křemenné ampuli) pomocí neizotermní DSC analýzy. Ze získaných výsledků a jejich porovnáním s fázovým diagramem CsCl-HfCl4 bylo možné získat důležité informace potřebné k optimalizaci růstu krystalů Cs2HfCl6 vertikální Bridgmanovou metodou. This contribution deals with the study of thermal behavior of CsCl-HfCl4 mixture of various composition (containing excess of Cs- or Hf-component) in enclosed system (quartz ampoule) by non-isothermal DSC analysis. Important information necessary for optimization of the Cs2HfCl6 crystal growth by the vertical Bridgman method were obtained from the comparison of the recorded results and the CsCl-HfCl4 phase diagram. Keywords: CsCl-HfCl.sub.4./sub.; thermal properties; DSC analysis in closed system Available at various institutes of the ASCR
Studium vlivu složení ve směsi CsCl-HfCl.sub.4./sub. na její tepelné vlastnosti v uzavřeném systému pomocí DSC analýzy

Příspěvek se zabývá studiem tepelného chování směsi CsCl-HfCl4 o různém složení (nadbytek Cs- nebo Hf-složky) v uzavřeném systému (křemenné ampuli) pomocí neizotermní DSC analýzy. Ze získaných ...

Král, Robert; Zemenová, Petra; Vaněček, Vojtěch; Bystřický, Aleš
Fyzikální ústav, 2020

Book of Abstracts of the 30.sup.th./sup. Joint Seminar of the Development of Materials Science in Research and Education
Kožíšek, Zdeněk; Král, Robert; Zemenová, Petra
2020 - English
Conference topics: \n- Trends in development of materials research\n- Education of materials science at the universities \n- Information about the research programmes of individual institutions \n- Information on equipment for preparation and characterisation of materials \n- Results of materials science research. Keywords: material sciences Available at various institutes of the ASCR
Book of Abstracts of the 30.sup.th./sup. Joint Seminar of the Development of Materials Science in Research and Education

Conference topics: \n- Trends in development of materials research\n- Education of materials science at the universities \n- Information about the research programmes of individual institutions \n- ...

Kožíšek, Zdeněk; Král, Robert; Zemenová, Petra
Fyzikální ústav, 2020

Závěrečná zpráva projektu „Efektivní využití odpadního tepla“ reg. č. CZ.07.1.02/0.0/0.0/16_040/0000384 realizovaném v rámci výzvy č. 24 OP PPR , technologie 3, stacionární vysokopotenciální zdroje odpadního tepla
Hejtmánek, Jiří; Stachura, Jan
2020 - Czech
Cílem projektu bylo ověřit možnost využití termoelektrických generátorů (dále TEG) k výrobě elektrické energie z odpadního tepla, které je produkováno spalováním fosilního paliva v dopravních prostředcích. S ohledem na charakter jízdního cyklu prostředků veřejné dopravy jsme se na základě konzultací a prozkoumání možností experimentálního testování soustředili na ověření možnosti lepšího využití energie produkované nezávislým topením (NT) s cílem alespoň částečného pokrytí jeho potřeby elektrické energie, která je nutná k jeho provozu. Při provozu NT v autobuse dochází totiž k odběru elektrické energie cca 360 W z elektrické soustavy autobusu, která je potřeba pro pohon oběhového čerpadla, ventilátorů topení a řídící elektroniky NT.\n The aim of the project was to use the waste thermal energy of flue gases or hot steam to produce electricity through thermoelectric generators (TEG). The local production of electricity at the place of its consumption will enable, for example, power source of autonomous sensors, including wireless transmission of necessary information to the control center or power source of safety lights, without installation of the electric cables from the distant power source, which is sometimes technologically difficult. Another specific possible utilization was aimed at the replacement of disposable batteries, which supply the necessary sensors and at the same time serve for sending data to the control center, which is energy demanding.\n Keywords: využití odpadniho tepla; termoelektrická konverse Available at various institutes of the ASCR
Závěrečná zpráva projektu „Efektivní využití odpadního tepla“ reg. č. CZ.07.1.02/0.0/0.0/16_040/0000384 realizovaném v rámci výzvy č. 24 OP PPR , technologie 3, stacionární vysokopotenciální zdroje odpadního tepla

Cílem projektu bylo ověřit možnost využití termoelektrických generátorů (dále TEG) k výrobě elektrické energie z odpadního tepla, které je produkováno spalováním fosilního paliva v dopravních ...

Hejtmánek, Jiří; Stachura, Jan
Fyzikální ústav, 2020

Mass production of hydrogenated ZnO nanorods
Chang, Yu-Ying; Remeš, Zdeněk; Míčová, J.
2020 - English
We have developed an inexpensive and efficient technology of hydrothermal growth of ZnO nanorods from zinc nitrate hexahydrate (Zn(NO3)2·6H2O), as a precursor and hexamethylenetetramine (HMTA) (C6H12N4), as a surfactant followed by plasma hydrogenation in a novel inductively coupled plasma (ICP) quartz reactor and equipped with the rotary sample holder to stir powder during plasma treatment. We have optimized the photoluminescence spectroscopy for measuring optical scattering samples with the high sensitivity, precise sample positioning and very low influence of the scattered excitation light. Here we present the latest results on the enhancement of the UV photoluminescence of the ZnO nanorods after plasma hydrogenation. The exciton-related photoluminescence has been significantly enhanced whereas the deep defect related yellow photoluminescence has been significantly decreased.\n Keywords: nanomaterials; ZnO; photoluminescence; excitons; inductively coupled plasma; hydrogenation Available at various institutes of the ASCR
Mass production of hydrogenated ZnO nanorods

We have developed an inexpensive and efficient technology of hydrothermal growth of ZnO nanorods from zinc nitrate hexahydrate (Zn(NO3)2·6H2O), as a precursor and hexamethylenetetramine (HMTA) ...

Chang, Yu-Ying; Remeš, Zdeněk; Míčová, J.
Fyzikální ústav, 2020

Laser-induced surface acoustic waves for thin film characterization
Kudělka, R.; Václavek, L.; Tomáštík, Jan; Malecová, S.; Čtvrtlík, R.
2020 - English
Knowledge of mechanical properties of thin films is essential for most of their applications.However, their determination can be problematic for very thin films. LAW (Laser-induced acousticwaves) is a combined acousto-optic method capable of measuring films with thickness from fewnanometers. It utilizes ultrasound surface waves which are excited via short laser pulses and detectedby a PVDF foil. Properties such as Young’s modulus, Poisson’s ratio and density of both the film andthe substrate as well as film thickness can be explored.Results from the LAW method are successfullycompared with nanoindentation for Young’s modulus evaluation and with optical method for filmthickness evaluation and also with literature data. Application of LAW for anisotropy mapping ofmaterials with cubic crystallographic lattice is also demonstrated Keywords: anisotropy; laser-induced surface acoustic waves; nanoindentation; Young’s modulus; thin films Available at various institutes of the ASCR
Laser-induced surface acoustic waves for thin film characterization

Knowledge of mechanical properties of thin films is essential for most of their applications.However, their determination can be problematic for very thin films. LAW (Laser-induced acousticwaves) is a ...

Kudělka, R.; Václavek, L.; Tomáštík, Jan; Malecová, S.; Čtvrtlík, R.
Fyzikální ústav, 2020

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