No (567)
Yes (21)
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588
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The peculiar outburst activity of the symbiotic binary AG Draconis
Gális, R.; Merc, J.; Leedjärv, L.; Vrašťák, M.; Karpov, Sergey
2019 - English
AG Draconis is a strongly interacting binary system which manifests characteristic symbiotic activity of alternating quiescent and active stages. The latter ones consist of the series of individual outbursts repeating at about a one-year interval. After seven years of flat quiescence following the 2006–2008 major outbursts, in the late spring of 2015, the symbiotic system AG Dra started to become brighter again toward what appeared to be a new minor outburst. The current outburst activity of AG Dra was confirmed by the following three outbursts in April 2016, May 2017 and April 2018. The photometric and spectroscopic observations suggest that all these outbursts are of the hot type. Such behaviour is considerably peculiar in almost 130-year history of observing of this object, because the major outbursts at the beginning of active stages are typically cool ones. In the present work, the current peculiar activity of the symbiotic binary AG Dra is described in detail.\n
Keywords:
AG Draconis; LC; outburst
Fulltext is available at external website.
The peculiar outburst activity of the symbiotic binary AG Draconis
AG Draconis is a strongly interacting binary system which manifests characteristic symbiotic activity of alternating quiescent and active stages. The latter ones consist of the series of individual ...
Model of carrier multiplication due to impurity impact ionization in boron-doped diamond
Mortet, Vincent; Lambert, Nicolas; Hubík, Pavel; Soltani, A.
2019 - English
Boron-doped diamond exhibits a characteristic S-shaped I-V curve at room temperature [1] with two electrical conductivity states, i.e., low and high conductivity, at high electric fields (50 – 250 kV.cm-1) due to the carrier freeze-out and impurity impact ionization avalanche effect. To our knowledge, the carrier multiplication during the change of the conductivity state has not been studied. In this article, we investigate theoretically the effect of acceptor concentration and compensation level on the carrier multiplication coefficient at room temperature to determine the optimal dopants concentration of maximum carrier multiplication. The room temperature hole concentration of boron-doped diamond has been calculated for various acceptor concentration and compensation ratio by solving numerically the charge neutrality equation within the Boltzmann approximation of the Fermi-Dirac statistic.\n
Keywords:
Boron-doped diamond; semiconductor; carrier multiplication coefficient; impurity impact ionization
Fulltext is available at external website.
Model of carrier multiplication due to impurity impact ionization in boron-doped diamond
Boron-doped diamond exhibits a characteristic S-shaped I-V curve at room temperature [1] with two electrical conductivity states, i.e., low and high conductivity, at high electric fields (50 – 250 ...
Germanium and tin nanoparticles encapsulated in amorphous silicon matrix for optoelectronic application
Stuchlíková, The-Ha; Remeš, Zdeněk; Stuchlík, Jiří
2019 - English
The plasma enhanced chemical vapour deposition was combined with in situ deposition of Ge and Sn thin film by evaporation technique at surface temperature about 220 °C to form nanoparticles on the surface of hydrogenated silicon thin films to prepare diodes. Formation of nanoparticles was additionally stimulated by plasma treatment through a low pressure hydrogen glow discharge. The diodes based on PIN diode structures with and without the embedded Ge or Sn nanoparticles were characterized by temperature dependence of electrical conductivity, activation energy of conductivity, measurement of volt-ampere characteristics in dark and under solar illumination\n
Keywords:
Ge NPs; a-Si:H; Sn NPs; diode structures; I-V characteristics
Available at various institutes of the ASCR
Germanium and tin nanoparticles encapsulated in amorphous silicon matrix for optoelectronic application
The plasma enhanced chemical vapour deposition was combined with in situ deposition of Ge and Sn thin film by evaporation technique at surface temperature about 220 °C to form nanoparticles on the ...
ZnMg0.8Ca/Sr0.2 ternary alloys - the influence of the third element on material properties
Čapek, Jaroslav; Pinc, Jan; Kubásek, J.; Molnárová, Orsolya; Maňák, Jan; Drahokoupil, Jan
2019 - English
Zinc-based materials alloyed with the elements of the 2nd group of the periodic table have been studied as potential materials for the fabrication of various biodegradable implants. In this study, we prepared two ternary alloys: ZnMg0.8Ca0.2 (wt.%) and ZnMg0.8Sr0.2. The microstructure of both ternary alloys was similar, the main difference was in the size and morphology of the Ca/SrZn13 phase. The SrZn13 phase formed fine particles with a submicron size and had more significant hardening effect in the as-cast state compared to the CaZn13 phase. The annealing led to a transformation of the eutectic structure into the “massive” Mg2Zn11 phase which caused a significant increase of both hardness and compressive yield stress. In the annealed states, comparable hardness was observed for both alloys and higher compressive yield strength for the Ca-containing alloy.
Keywords:
biodegradable zinc alloys; mechanical properties; microstructure
Available in digital repository of the ASCR
ZnMg0.8Ca/Sr0.2 ternary alloys - the influence of the third element on material properties
Zinc-based materials alloyed with the elements of the 2nd group of the periodic table have been studied as potential materials for the fabrication of various biodegradable implants. In this study, we ...
Book of Abstracts of the 28th Joint Seminar "Development of Materials Science in Research and Education"
Kožíšek, Zdeněk; Král, Robert; Zemenová, Petra
2018 - English
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 28th Joint Seminar "Development of Materials Science in Research and Education"
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 ...
The hydrogen plasma doping of ZnO thin films and nanoparticles
Remeš, Zdeněk; Neykova, Neda; Potocký, Štěpán; Chang, Yu-Ying; Hsu, H.S.
2018 - English
The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass substrate by the hydrothermal process in an oil bath containing a flask with ZnO nutrient solution. The localized defect states at 2.3 eV below the optical absorption edge were detected by photothermal deflection spectroscopy (PDS) in a broad spectral range from near UV to near IR. The optical absorptance spectroscopy shows that hydrogen doping increases free electron concentration changing ZnO to be electrically conductive (hydrogen doping).\n
Keywords:
ZnO; nanoparticles; hydrothermal growth; hotoluminescence spectroscopy; PDS
Available at various institutes of the ASCR
The hydrogen plasma doping of ZnO thin films and nanoparticles
The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass ...
Influence of Si doping in different layers on luminescence properties of InGaN/GaN multiple quantum well structure
Hájek, František; Hospodková, Alice; Oswald, Jiří; Slavická Zíková, Markéta
2018 - English
Luminescence of InGaN/GaN multiple quantum well (MQW) structure is strongly affected by spontaneous and piezoelectric polarizations. To suppress them, doping with shallow impurities (e. g. Si) can be used. This works presents the effects of Si doping in different layers around the MQW area. On the basis of photoluminescence and cathodoluminescence measurements and band structure simulation, the piezoelectric field is most efficiently reduced when both layers under and over MQW area are Si doped.\n
Keywords:
nitrides; quantum wells; luminescence; semiconductor doping
Fulltext is available at external website.
Influence of Si doping in different layers on luminescence properties of InGaN/GaN multiple quantum well structure
Luminescence of InGaN/GaN multiple quantum well (MQW) structure is strongly affected by spontaneous and piezoelectric polarizations. To suppress them, doping with shallow impurities (e. g. Si) can be ...
Study of cesium hafnium chloride by methods of thermal analysis
Král, Robert; Zemenová, Petra; Bystřický, Aleš; Vaněček, Vojtěch; Kohoutková, M.
2018 - Czech
This work deals with the study of processes in cesium hafnium chloride (Cs2HfCl6) and its single crystal under thermal treatment by thermal analyses (different scanning calorimetry, thermogravimetry and thermomechanical analysis). Results showed thermal instability of Cs2HfCl6 and its significant decomposition to cesium and hafnium chloride above the eutectic temperature. Tato práce se zabývá studiem procesů probíhajících při tepelném zatížení připraveného chloridu cesno-hafničitého (Cs2HfCl6) a jeho monokrystalu metodami termické analýzy: simultánní diferenciální skenovací kalorimetrií a termogravimetrií (DSC-TG) a termomechanickou analýzou (TMA). Výsledky prokázaly tepelnou nestabilitu Cs2HfCl6 a jeho rozklad na chlorid cesný a hafničitý nad eutektickou teplotou.\n
Keywords:
Cs.sub.2./sub.HfCl.sub.6./sub.; DSC-TG; TMA; krystal
Available at various institutes of the ASCR
Study of cesium hafnium chloride by methods of thermal analysis
This work deals with the study of processes in cesium hafnium chloride (Cs2HfCl6) and its single crystal under thermal treatment by thermal analyses (different scanning calorimetry, thermogravimetry ...
Secure erasing memory chips using electromagnetic pulse - phase 1
Fitl, Přemysl; Vrňata, M.; Fišer, L.; Novotný, Michal; Scholtz, V.; Vlček, J.; Tomeček, D.
2018 - Czech
The subject of this contractual research was to perform study of technologies and principles of flash memories currently available on the market. The research report focuses on technological advancements in their development, the readability of stored / deleted data by available laboratory techniques, and the interaction of these memories with the electromagnetic pulse.\nThe outcome was handed over to NUKIB representatives on 29 March 2018. \nThe project was fulfilled, the agreed amount was invoiced for this report.\n\n\n Předmětem smluvního výzkumu bylo provedení rešerše principu funkce pamětí typu flash aktuálně dostupných na trhu. Souhrnná výzkumná zpráva popisuje technologický pokrok v jejich vývoji, možnosti vyčítání uložených/smazaných dat dostupnými laboratorními technikami a interakci těchto pamětí s elektromagnetickým pulzem.\nVýstup byl předán zástupcům NÚKIB dne 29.3.2018. Projekt byl splněn, za vypracování této zprávy byla fakturována sjednaná částka.\n\n
Keywords:
flash memory; memory erasing; electromagnetic pulse
Available at various institutes of the ASCR
Secure erasing memory chips using electromagnetic pulse - phase 1
The subject of this contractual research was to perform study of technologies and principles of flash memories currently available on the market. The research report focuses on technological ...
Plasma deposition system for long electrically conductive tubes
Hubička, Zdeněk
2018 - Czech
The report describes a plasma deposition method with pulsed hollow cathode for coatings of long electrically conductive tubes. Zpráva popisuje plazmatickou metodu využívající pulzní výboj v duté katodě pro povlakování dlouhých elektricky vodivých trubek.
Keywords:
plasma; hollow cathode discharge; thin film
Available at various institutes of the ASCR
Plasma deposition system for long electrically conductive tubes
The report describes a plasma deposition method with pulsed hollow cathode for coatings of long electrically conductive tubes.
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