Number of found documents: 576
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XXIV Czech-Polish seminar: Structural and ferroelectric phase transitions: Book of abstracts and program
Pokorný, Jan; Bubnov, Alexej; Janovská, Marie
2022 - English
This is the Book of Abstracts for the XXIV Czech-Polish Seminar (CPSEM-2022 conference) held in Harrachov (Czech Republic) on May 23 - 27, 2022. The special objective of the conference is expressed in the conference subtitle: Structural and Ferroelectric Phase Transitions. The continuous worldwide interest to this conference series is proving that it has a respected position within the series of International/European conferences covering all interdisciplinary field of the research related to structural and ferroelectric phase transitions. At the CPSEM-2022 conference there were about 100 participants from 10 countries delivered 8 tutorial lectures for early stage researchers, 8 invited lectures and selected 34 oral contributions. More than 55 posters were presented during two poster sessions. Keywords: Czech-Polish seminar; structural and ferroelectric phase transition Available at various institutes of the ASCR
XXIV Czech-Polish seminar: Structural and ferroelectric phase transitions: Book of abstracts and program

This is the Book of Abstracts for the XXIV Czech-Polish Seminar (CPSEM-2022 conference) held in Harrachov (Czech Republic) on May 23 - 27, 2022. The special objective of the conference is expressed in ...

Pokorný, Jan; Bubnov, Alexej; Janovská, Marie
Fyzikální ústav, 2022

Plasma-synthesised zinc oxide nanoparticle behavior in liquids
Rutherford, D.; Jíra, J.; Kolářová, Kateřina; Matolínová, I.; Remeš, Zdeněk; Kuliček, J.; Padmanaban, D.; Maguire, P.; Mariotti, D.; Rezek, B.
2022 - English
ZnO nanoparticles have been synthesized using non-thermal atmospheric pressure plasma (ZnO-NTP). We investigated the behavior of these ligand-free as a colloid suspension using different solvents, from deionized water to physiological saline and microbial culture broth. We found that the zeta potential of ZnONTP became more negative after exposure to microbial culture broth relative to water, which suggests increased colloid stability. Photoluminescence spectra of ZnO-NTP were similar regardless of liquid type, yet optical and fluorescent images of samples showed different agglomeration behaviour depending on liquid type. Scanning electron microscopy images revealed large agglomerates of ZnO-NTP interacting with the surface of bacteria cells, ranging in size from 200 nm up to 2 µm. We also studied effect of sub-lethal concentrations of ZnO-NTP on bacteria under illumination. There was no significant difference in viable bacteria concentration after 24h exposure to 10 µg/mL ZnO-NTP. Keywords: zinc oxide; nanotechnology; colloid suspension; bacteria Available at various institutes of the ASCR
Plasma-synthesised zinc oxide nanoparticle behavior in liquids

ZnO nanoparticles have been synthesized using non-thermal atmospheric pressure plasma (ZnO-NTP). We investigated the behavior of these ligand-free as a colloid suspension using different solvents, ...

Rutherford, D.; Jíra, J.; Kolářová, Kateřina; Matolínová, I.; Remeš, Zdeněk; Kuliček, J.; Padmanaban, D.; Maguire, P.; Mariotti, D.; Rezek, B.
Fyzikální ústav, 2022

Termická analýza vstupních surovin pro růst krystalů vysokoteplotních komplexních oxidů
Zemenová, Petra; Král, Robert; Falvey, Alexandra; Pejchal, Jan; Bystřický, Aleš
2022 - Czech
Příspěvek se zabývá studiem tepelného chování oxidů vzácných zemin (La2O3, Sc2O3 a Gd2O3), které se používají jako výchozí suroviny při přípravě krystalů komplexních oxidů na bázi granátů a perovskitů, pomocí metod DSC-TG-MS. This contribution deals with the study of thermal behavior of oxide La2O3, Sc2O3 a Gd2O3 by methods DSC-TG-MS. Keywords: thermal analysis DSC-TG; mass spectrometry; oxide; high-temperature complex oxides crystals Available at various institutes of the ASCR
Termická analýza vstupních surovin pro růst krystalů vysokoteplotních komplexních oxidů

Příspěvek se zabývá studiem tepelného chování oxidů vzácných zemin (La2O3, Sc2O3 a Gd2O3), které se používají jako výchozí suroviny při přípravě krystalů komplexních oxidů na bázi granátů a ...

Zemenová, Petra; Král, Robert; Falvey, Alexandra; Pejchal, Jan; Bystřický, Aleš
Fyzikální ústav, 2022

Emergence of dark ZnO nanorods by hydrogen plasma treatment
Remeš, Zdeněk; Buryi, Maksym; Sharma, Dhananjay K.; Artemenko, Anna; Mičová, J.; Rezek, B.; Poruba, A.; Hsu, H.S.; Potocký, Štěpán; Babin, Vladimir
2022 - English
We employed a custom-built inductively coupled plasma (ICP) 13.56 MHz reactor with up to 300 W RF discharge power. Hydrothermally grown ZnO nanorods were exposed to the ICP plasma with a mixture of hydrogen and argon for up to 30 min, followed in-situ by plasma oxidation. Plasma properties were monitored by optical emission spectroscopy (OES) and by measuring the self-bias potential of the stainless steel sample holder separated from the ground by a blocking capacitor. The exciton-related UV photoluminescence of ZnO nanorods and optical absorption increases significantly after the plasma treatment. We attribute it to the complex changes of ZnO surface electronic states that also give rise to its black color visually. Keywords: ZnO; ICP; photoluminescence Fulltext is available at external website.
Emergence of dark ZnO nanorods by hydrogen plasma treatment

We employed a custom-built inductively coupled plasma (ICP) 13.56 MHz reactor with up to 300 W RF discharge power. Hydrothermally grown ZnO nanorods were exposed to the ICP plasma with a mixture of ...

Remeš, Zdeněk; Buryi, Maksym; Sharma, Dhananjay K.; Artemenko, Anna; Mičová, J.; Rezek, B.; Poruba, A.; Hsu, H.S.; Potocký, Štěpán; Babin, Vladimir
Fyzikální ústav, 2022

Vliv velikosti zrn práškového NaCl na jeho termické vlastnosti
Falvey, Alexandra; Zemenová, Petra; Vaněček, Vojtěch; Bystřický, Aleš; Stehlík, Štěpán; Král, Robert
2022 - Czech
Příspěvek se zabývá studiem tepelného chování vzorku NaCl v práškové formě (s homogenní a nehomogenní distribucí zrn, různou vlhkostí) a monokrystalického NaCl metodami termické analýzy (DSC a TMA) a hmotnostní spektrometrii (MS). The paper deals with the study of the thermal behavior of a sample of NaCl in powder form (with homogeneous and inhomogeneous grain distribution, different humidity) and monocrystalline NaCl using the methods of thermal analysis (DSC and TMA) and mass spectrometry (MS). Keywords: thermal analysis Available at various institutes of the ASCR
Vliv velikosti zrn práškového NaCl na jeho termické vlastnosti

Příspěvek se zabývá studiem tepelného chování vzorku NaCl v práškové formě (s homogenní a nehomogenní distribucí zrn, různou vlhkostí) a monokrystalického NaCl metodami termické analýzy (DSC a TMA) a ...

Falvey, Alexandra; Zemenová, Petra; Vaněček, Vojtěch; Bystřický, Aleš; Stehlík, Štěpán; Král, Robert
Fyzikální ústav, 2022

Magnetocrystalline anisotropy of Ni-Mn-Ga-Co-Cu martensite
Rameš, Michal; Straka, Ladislav; Sozinov, A.; Heczko, Oleg
2022 - English
The martensites of Heusler alloys based on Ni-Mn-Ga exhibit magnetically-induced reorientation resulting in giant field-induced strain. Up to 12% strain was observed in Ni-Mn-Ga-Co-Cu with 4 at.% of Co and Cu. The driving force of the phenomenon is the magnetocrystalline anisotropy. We studied evolution of the anisotropy with temperature and compositions using magnetiyation curve measurements in four different single crystalline Ni-Mn-Ga-Co-Cu and compared with non-doped Ni-Mn-Ga. The anisotropy of martensite decreases with increasing average doping (Co+Cu)/2 but it does not scale with tetragonal ratio or valence electron concentration. Keywords: martensite; magnetocrystalline anisotropy; Heusler alloys; Ni-Mn-Ga Available at various institutes of the ASCR
Magnetocrystalline anisotropy of Ni-Mn-Ga-Co-Cu martensite

The martensites of Heusler alloys based on Ni-Mn-Ga exhibit magnetically-induced reorientation resulting in giant field-induced strain. Up to 12% strain was observed in Ni-Mn-Ga-Co-Cu with 4 at.% of ...

Rameš, Michal; Straka, Ladislav; Sozinov, A.; Heczko, Oleg
Fyzikální ústav, 2022

Chemická depozice diamantových tenkých vrstev z par plynů
Kromka, Alexander
2022 - Czech
Příprava diamantových vrstev a jejich (nano-) struktur vyžaduje zvládnutí více technologických kroků. V prvním kroku „diamantové technologie” je důležité aktivovat povrch nediamantové podložky vhodným procesem známým jako nukleace nebo zárodkování. Nejčastěji se jedná o proces pokrytí povrchu podložky (nano-) částicemi diamantu nebo aktivace povrchu podložky iontovým bombardováním. Druhým klíčovým krokem je samotný růst diamantové vrstvy tzv. chemickou depozicí z par plynů (tzv. „Chemical Vapor Deposition” - CVD) za nízkých tlaků (10 ÷ 10 000 Pa) a teplot v rozsahu 250 ÷ 1000 °C, která je nejčastěji realizována v plynné směsi metanu a vodíku v systému žhaveného vlákna nebo mikrovlnného plazmatu. V tomto příspěvku jsou oba technologické kroky, nukleace a růst, diskutovány se zřetelem aktuálních trendů a experimentálních aktivit probíhajících v laboratořích Fyzikálního ústavu AV ČR (FZÚ).\n The preparation of diamond layers and their (nano-) structures requires the optimization of several technological steps. In the first step of “diamond technology” it is important to activate the surface of the non-diamond substrate by a suitable process known as nucleation or nucleation. The second key step is the growth of the diamond layer itself by chemical vapor deposition (CVD) under low pressures (10 ÷ 10,000 Pa) and temperatures in the range of 250 ÷ 1000 °C, and from a gas mixture of methane and hydrogen commonly used in a hot filament or microwave plasma CVD systems. In this paper, both technological steps, nucleation and growth, are discussed in light of current trends and experimental activities taking place in the laboratories of the Institute of Physics of the Academy of Sciences of the Czech Republic (FZÚ). Keywords: diamond technology; nucleation; chemical vapor deposition Available at various institutes of the ASCR
Chemická depozice diamantových tenkých vrstev z par plynů

Příprava diamantových vrstev a jejich (nano-) struktur vyžaduje zvládnutí více technologických kroků. V prvním kroku „diamantové technologie” je důležité aktivovat povrch nediamantové podložky vhodným ...

Kromka, Alexander
Fyzikální ústav, 2022

Development and measurement of gas sensors for room temperature applications
Kočí, Michal
2022 - English
Gas sensing properties of a nanocrystalline diamond with a hydrogen-terminated surface (H-terminated NCD) and a molybdenum disulphide (MoS2) are investigated as conductivity sensors with built-in interdigital metal electrode structures. The H-terminated NCD was prepared by plasma-enhanced chemical vapour deposition (PECVD), and the MoS2 by a carbide-free one-zone sulfurization method. The sensor's responses were measured for oxidizing (NO2) and reducing (NH3) gases by the same equipment and setup. The parameters of the tested sensors are compared and critically evaluated. Advantageously, the MoS2/H-terminated NCD heterostructure enhances the gas sensing response at room temperature compared to the H-terminated NCD and MoS2 layers. Keywords: gas sensor; nanocrystalline diamond (NCD); transition metal dichalcogenide (TMD) Fulltext is available at external website.
Development and measurement of gas sensors for room temperature applications

Gas sensing properties of a nanocrystalline diamond with a hydrogen-terminated surface (H-terminated NCD) and a molybdenum disulphide (MoS2) are investigated as conductivity sensors with built-in ...

Kočí, Michal
Fyzikální ústav, 2022

Transformation of ZnO-based structures under heavy Mo doping: Defect states and luminescence
Buryi, Maksym; Remeš, Zdeněk; Děcká, Kateřina; Mičová, J.; Landová, Lucie
2022 - English
Hydrothermally grown ZnO-based structures were heavily doped with Mo (various doping levels from 2 to 25%). It has been found that Mo strongly affects the ZnO structure and morphology rather resulting in the complex, mixed zinc and molybdenum oxides creation. Moreover, the material phases transformation upon the increased Mo content was observed. ZnO material phase was observed only at low Mo doping level (2 and 5%). This correlated very well to the changes in the luminescence and electron paramagnetic resonance signals. Keywords: ZnO; Mo doping; material phase transformation; luminescence; electron paramagnetic resonance Fulltext is available at external website.
Transformation of ZnO-based structures under heavy Mo doping: Defect states and luminescence

Hydrothermally grown ZnO-based structures were heavily doped with Mo (various doping levels from 2 to 25%). It has been found that Mo strongly affects the ZnO structure and morphology rather resulting ...

Buryi, Maksym; Remeš, Zdeněk; Děcká, Kateřina; Mičová, J.; Landová, Lucie
Fyzikální ústav, 2022

General overview of GaN devices and transport properties of AlGaN/GaN HEMT structures - impact of dislocation density and improved design
Hulicius, Eduard; Hájek, František; Hospodková, Alice; Hubík, Pavel; Gedeonová, Zuzana; Hubáček, Tomáš; Pangrác, Jiří; Kuldová, Karla
2022 - English
GaN-based nanostructures are used for many present semiconductor devices. The main topics are structures for blue LEDs and LDs, but there are also other interesting and important GaN devices namely for power electronics, scintillators and detectors as well as High Electron Mobility Transistors (HEMT). Reduction of dislocation density considerably increases electron mobility in 2DEG. All presented results support our expectation that a suitably designed AlGaN back barrier can help to prevent this phenomenon. Keywords: GaN devices; HEMT; MOVPE epitaxy; dislocation Available at various institutes of the ASCR
General overview of GaN devices and transport properties of AlGaN/GaN HEMT structures - impact of dislocation density and improved design

GaN-based nanostructures are used for many present semiconductor devices. The main topics are structures for blue LEDs and LDs, but there are also other interesting and important GaN devices namely ...

Hulicius, Eduard; Hájek, František; Hospodková, Alice; Hubík, Pavel; Gedeonová, Zuzana; Hubáček, Tomáš; Pangrác, Jiří; Kuldová, Karla
Fyzikální ústav, 2022

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