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Příprava vzorků
Kopeček, Jaromír
2016 - Czech
Základní shrnutí metalografických a materiálografických postupů a technik pro přípravu vzorků pro mikrosvazkovou analýzu v SEM a příbuzné techniky. The basic summyry of metallography and materialography as it is exploited for SEM samples´ preparation and connected techniques.
Keywords:
SEM; metallography
Available at various institutes of the ASCR
Příprava vzorků
Základní shrnutí metalografických a materiálografických postupů a technik pro přípravu vzorků pro mikrosvazkovou analýzu v SEM a příbuzné techniky....
Difrakce zpět rozptýlených elektronů
Kopeček, Jaromír
2016 - Czech
Nástin metody EBSD dokumentující použitelnost metody, typické úkoly a aplikace. Outline of the EBSD method, its use, tasks and typical applications.
Keywords:
EBSD method; SEM; microstructure
Available at various institutes of the ASCR
Difrakce zpět rozptýlených elektronů
Nástin metody EBSD dokumentující použitelnost metody, typické úkoly a aplikace.
Outline of the EBSD method, its use, tasks and typical applications.
Laser-driven ablation through fast electrons in PALS experiment
Gus'kov, S. Yu.; Chodukowski, T.; Demchenko, N.; Kalinowska, Z.; Kasperczuk, A.; Krouský, Eduard; Pfeifer, Miroslav; Pisarczyk, P.; Pisarczyk, T.; Renner, Oldřich; Skála, Jiří; Šmíd, Michal; Ullschmied, Jiří
2016 - English
Energy transfer to shock wave in Al and Cu targets irradiated by a laser pulse with intensity of I~1-50 PW/cm2 and duration of 250 ps was investigated at Prague Asterix Laser System (PALS). The iodine laser provided energy in the range of 100-600 J at the first and third harmonic frequencies. The focal spot radius of laser beam on the target was varied from 160 to 40 µm. The dominant contribution of fast electron energy transfer into the ablation process was found when using the first harmonic radiation, the focal spot radius of 40-100 µm, and the energy of 300-600 J. The fast electron heating results in the growth of ablation pressure from 60 Mbar at the intensity of 10 PW/cm2 to 180 Mbar at the intensity of 50 PW/cm2 and in the growth of the efficiency of the energy conversion into the shock wave from 2 to 7 % under the conditions of 2D ablation.
Keywords:
laser-produced plasma; ablation pressure
Available at various institutes of the ASCR
Laser-driven ablation through fast electrons in PALS experiment
Energy transfer to shock wave in Al and Cu targets irradiated by a laser pulse with intensity of I~1-50 PW/cm2 and duration of 250 ps was investigated at Prague Asterix Laser System (PALS). The iodine ...
Aproximace Fourierových koeficientů difrakčních profilů
Čerňanský, Marian
2016 - Czech
Je podán stručný přehled aproximací, které se vyskytují ve Warrenově–Averbachově interpretaci Fourierových koeficientů difrakčních profilů. Je ukázáno, že jisté aproximace průběhu Fourierových koeficientů umožňují stanovit velikost krystalitů a mikrodeformací jen z jedné difrakční linie.\n\n Approximations in the Warren-Averbach interpretation of Fourier coeeficients of diffraction profiles are briefly summarized. It is shown, that certain approximations of a course of Fourier coefficients enable estimate of crystallite size and microstrain only from a single diffraction line.
Keywords:
line profile analysis; Fourier coefficients; crystallite size; microstrain
Available at various institutes of the ASCR
Aproximace Fourierových koeficientů difrakčních profilů
Je podán stručný přehled aproximací, které se vyskytují ve Warrenově–Averbachově interpretaci Fourierových koeficientů difrakčních profilů. Je ukázáno, že jisté aproximace průběhu Fourierových ...
Geometric resonances in reflectivity spectra of lead zirconate
Dočekalová, Zuzana; Hlinka, Jiří
2016 - English
The paper deals with effects of domain boundaries on the THz–frequency range dispersion of the complex dielectric permitivity tensor of lead zirconate. In the case of a sufficiently narrow domain widths (in comparison to the wave–length of the light used in the experiment), the effective–medium average permittivity shows additional peaks identified as geometric resonances, i.e. extraneous excitations created by thematerial interface. Features of the far–infrared reflectivity spectra of the twinned lead zirconate crystal in the limit of narrow and wide domains are estimated with the\nhelp of the damped harmonic oscillator model with paramaters fully determined fromrecent experiments.
Keywords:
geometric resonances; lead zirconate; antiferroelectrics; reflectivity; phonon
Available at various institutes of the ASCR
Geometric resonances in reflectivity spectra of lead zirconate
The paper deals with effects of domain boundaries on the THz–frequency range dispersion of the complex dielectric permitivity tensor of lead zirconate. In the case of a sufficiently narrow domain ...
Cryogenic cooling system Brayton for 10 J/10 Hz Yb:YAG multi-slab based laser system at ELI-Beamlines project
Schustr, P.; Fibrich, Martin; Polan, Jiří; Rus, Bedřich; Dostálová, M.; Valdislav, P.; Simek, J.
2016 - English
We present design and operational prototype of cryogenic cooling system based on Bryton's cycle for 10J/10Hz Yb:YAG multi-slab laser system at ELI-Beamlines project.
Keywords:
Brayton; cryogenics; laser; cooling; ytterbium; design; prototype
Available at various institutes of the ASCR
Cryogenic cooling system Brayton for 10 J/10 Hz Yb:YAG multi-slab based laser system at ELI-Beamlines project
We present design and operational prototype of cryogenic cooling system based on Bryton's cycle for 10J/10Hz Yb:YAG multi-slab laser system at ELI-Beamlines project.
Microscopic characterization of graphene material and electronic quality across neighbouring, differently oriented copper grains
Čermák, Jan; Yamada, T.; Ganzerová, Kristína; Rezek, Bohuslav
2015 - English
We study graphene grown across the boundary of three such grains having bright, medium, and dark color in reflection. Raman micro-spectroscopy proves presence of mostly a monoor bi-layer graphene on all the grains. Yet intensity of Raman 2D band is grain-dependent: highest at the darkest grain and lowest at the brightest one. Contrary, conductive atomic force microscopy detects the highest conductivity at the brightest grain and the lowest current at the darkest grain. This is attributed to dominant electrical current path through graphene and underlying oxide thickness of which also depends on the type of copper grain. We correlate and discuss the results with view to better understanding of graphene growth and electronic properties on large area copper substrates.
Keywords:
graphene; chemical vapor deposition; atomic force microscopy; Raman spectroscopy; electronic properties
Available at various institutes of the ASCR
Microscopic characterization of graphene material and electronic quality across neighbouring, differently oriented copper grains
We study graphene grown across the boundary of three such grains having bright, medium, and dark color in reflection. Raman micro-spectroscopy proves presence of mostly a monoor bi-layer graphene on ...
Magnetic domains under mechanical stress in single crystal Ni-Mn-Ga
Kopecký, Vít; Heczko, Oleg
2015 - English
The complexity of Ni-Mn-Ga single crystal lies in combination of ferromagnetic domain structure and ferroelastic twinned microstructure. Magnetic domain structure for different twinned microstructure was studied using magneto-optical indicator film. Different orientations of magnetic domains can be observed at the same place of the sample thanks to magnetically induced structural reorientation by movement of twin boundaries. We investigated experimentally the changes of magnetic domain structure in the vicinity of mobile a/c twin boundary.
Keywords:
Ni-Mn-Ga; magnetic domains; twin boundary
Available at various institutes of the ASCR
Magnetic domains under mechanical stress in single crystal Ni-Mn-Ga
The complexity of Ni-Mn-Ga single crystal lies in combination of ferromagnetic domain structure and ferroelastic twinned microstructure. Magnetic domain structure for different twinned ...
Diamond coated AlGaN/GaN high electron mobility transistors - effect of deposition process on gate electrode
Vanko, G.; Ižák, Tibor; Babchenko, O.; Kromka, Alexander
2015 - English
We studied the influence of the diamond deposition on the degradation of Schottky gate electrodes (i.e. Ir or IrO2) and on the electrical characteristics of AlGaN/GaN high electron mobility transistors (HEMTs). In present study, the diamond films were selectively deposited on the AlGaN/GaN circular HEMT by focused (ellispoidal cavity reactor) and linear antenna (surface wave) microwave plasma at different temperatures from 400°C to 1100°C. The preliminary results on electrical measurements on the diamond-coated c-HEMTs showed degraded electrical properties comparing to c-HEMTs before deposition process, which was attributed to degradation of the Ir gate electrodes even at temperatures as low as 400°C. On the other hand, metal oxide gate electrode layer (IrO2) can withstand diamond CVD process even at high temperatures (~900°C) which make it suitable for fabrication of all-in-diamond c-HEMT devices for high-power applications.
Keywords:
GaN HEMT; CVD diamond; iridium oxide; thermal stability; IV characteristics
Available at various institutes of the ASCR
Diamond coated AlGaN/GaN high electron mobility transistors - effect of deposition process on gate electrode
We studied the influence of the diamond deposition on the degradation of Schottky gate electrodes (i.e. Ir or IrO2) and on the electrical characteristics of AlGaN/GaN high electron mobility ...
Scanning thermal microscopy of thermoelectric pulsed laser deposited nanostructures
Vaniš, Jan; Zelinka, Jiří; Zeipl, Radek; Jelínek, Miroslav; Kocourek, Tomáš; Remsa, Jan; Navrátil, Jiří
2015 - English
New materials with high possible figure of merit ZT are of high interest as a promising candidates for thermoelectric applications such as energy harvesting. Miniaturization of such systems tends toward developing of the suitable characterization method with nanometer resolution ability. In our contribution, we present the development and experimental results of a simple scanning probe microscopy method for the relative thermal conductivity characterization. The possibility of the setup is demonstrated on the set of different thin thermoelectric layers grown from hot pressed targets by pulsed laser deposition on the reference Si substrate. All the measurements were performed on the commercial Veeco Multimode scanning AFM/STM microscope with home developed controller and by using PicoCal Inc. bolometer probes with tungsten resistive path. All the experiments were done in the air at the ambient condition. Additional sample treatment for the measurement will be also briefly described
Keywords:
Scanning thermal microscopy; figure of merit; thermoeletric materials
Available at various institutes of the ASCR
Scanning thermal microscopy of thermoelectric pulsed laser deposited nanostructures
New materials with high possible figure of merit ZT are of high interest as a promising candidates for thermoelectric applications such as energy harvesting. Miniaturization of such systems tends ...
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