Number of found documents: 411
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Room temperature ethanol detection using carbon materials
Kočí, Michal
2023 - English
Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and extraordinary physical and chemical properties, preferable for many different applications, including sensor devices. This work focuses on responses of various sensing layers (NCD with hydrogen termination (H-NCD), graphene oxide (GO), reduced graphene oxide (rGO), thiol-functionalized graphene oxide (GO-SH) and their hybrid structures to ethanol vapor with concentrations up to 100 ppm in synthetic air at room temperature. The measured parameters of the tested sensors, especially stability, reproducibility and regeneration, are compared and critically evaluated. The high sensitivity of tested sensors achieved at room temperature makes them very promising for monitoring ethanol vapor as well as other volatile substances (e.g., isopropyl-alcohol or acetone). Keywords: gas sensor; nanocrystalline diamond (NCD); graphene oxide (GO); reduced graphene oxide (rGO); thiol-functionalized graphene oxide (GO-SH) Available at various institutes of the ASCR
Room temperature ethanol detection using carbon materials

Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and ...

Kočí, Michal
Fyzikální ústav, 2023

Technological challenges in the fabrication of MoS.sub.2./sub./diamond heterostructures
Varga, Marián; Sojková, M.; Hrdá, J.; Hutar, P.; Parsa Saeb, S.; Vanko, G.; Pribusova Slusna, L.; Ondič, Lukáš; Fait, Jan; Kromka, Alexander; Hulman, M.
2023 - English
Nowadays, 2D materials are one of the most studied classes of materials. In addition to the most famous graphene, progress has been achieved in studying and using fundamental properties of transition metal dichalcogenides (TMD). Complementary, diamond as a representative of 3D materials has gained a reputation as an extremely versatile material due to its extraordinary combination of physical/chemical/electrical/optical properties. Besides these particular forms of 2D and 3D materials, their heterostructures have become very attractive due to new phenomena and functions (bandgap engineering, enhanced charge transport, optical interaction, etc.). However, individual technological procedures are still minimally investigated and described. Here, we will demonstrate a proof-of-concept for the preparation of MoS2/diamond heterostructures, where two different strategies were employed: a) growth of MoS2 layers on diamond films, and b) growth of diamond films on Si/MoS2 substrates. Keywords: transition metal dichalcogenides; molybdenum disulfide; diamond; heterostructures Available at various institutes of the ASCR
Technological challenges in the fabrication of MoS.sub.2./sub./diamond heterostructures

Nowadays, 2D materials are one of the most studied classes of materials. In addition to the most famous graphene, progress has been achieved in studying and using fundamental properties of transition ...

Varga, Marián; Sojková, M.; Hrdá, J.; Hutar, P.; Parsa Saeb, S.; Vanko, G.; Pribusova Slusna, L.; Ondič, Lukáš; Fait, Jan; Kromka, Alexander; Hulman, M.
Fyzikální ústav, 2023

Enhanced growth rate of diamond films at low temperature in focused microwave plasma system
Babčenko, Oleg; Bydžovská, Irena; Fait, Jan; Shagieva, Ekaterina; Ondič, Lukáš; Kromka, Alexander
2023 - English
The low temperature (< 500 °C) diamond film deposition on fused silica in two different focused microwave plasma systems, i.e. a multimode clamshell cavity (MCC) and a rotational ellipsoid cavity (REC) reactor, was investigated. During the experiments, the methane to hydrogen ratio, in the hydrogen-rich process gas mixture, varied from 1 % to 15 % for MCC and from 1 % to 9 % for REC. The grown films were analyzed by scanning electron microscopy and Raman shift measurements. The outcomes of the study and enhanced diamond growth at low temperatures is advantageous for overcoating of fused silica as well as thermally sensitive substrates, e.g. optical elements, photonic crystals, sensors, etc. Keywords: well-faceted diamonds; low temperature deposition; high growth rate; low non-diamond content; focused plasma Available at various institutes of the ASCR
Enhanced growth rate of diamond films at low temperature in focused microwave plasma system

The low temperature (...

Babčenko, Oleg; Bydžovská, Irena; Fait, Jan; Shagieva, Ekaterina; Ondič, Lukáš; Kromka, Alexander
Fyzikální ústav, 2023

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

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

Effect of molecular structure on liquid crystalline behaviour for chiral lactic acid derivatives
Mironov, Sergei; Bubnov, Alexej
2022 - English
Liquid crystals are self-organizing materials that have great potential for practical applications. The relationship has not been fully established and understood despite numerous studies. We discuss a relatively broad subclass of calamitic chiral lactic acid derivatives and provide specific examples of effective tuning of their mesomorphic and electro-optical behaviour using various types of lateral substitution placed on the molecular core. Keywords: chiral liquid crystals; lateral substitution; ferroelectric smectic phase; spontaneous polarization; lactic acid Available at various institutes of the ASCR
Effect of molecular structure on liquid crystalline behaviour for chiral lactic acid derivatives

Liquid crystals are self-organizing materials that have great potential for practical applications. The relationship ...

Mironov, Sergei; Bubnov, Alexej
Fyzikální ústav, 2022

Nanostructured layer enhancing light extraction from GaN-based scintillator using MOVPE
Vaněk, Tomáš; Hubáček, Tomáš; Hájek, František; Dominec, Filip; Pangrác, Jiří; Kuldová, Karla; Oswald, Jiří; Hospodková, Alice
2021 - English
Light extraction (LE) efficiency of GaN buffer layer was studied by angle-resolved photoluminescence. We measured enhancement of light extraction efficiency (LEE) up to 154% by introducing the SiNx layer atop the GaN buffer and subsequent GaN light extraction layer (LEL) overgrowth. Morphological properties of GaN. Keywords: MOVPE; GaN; light extraction; SiNx; scintillator Available at various institutes of the ASCR
Nanostructured layer enhancing light extraction from GaN-based scintillator using MOVPE

Light extraction (LE) efficiency of GaN buffer layer was studied by angle-resolved photoluminescence. We measured enhancement of light extraction efficiency (LEE) up to 154% by introducing the SiNx ...

Vaněk, Tomáš; Hubáček, Tomáš; Hájek, František; Dominec, Filip; Pangrác, Jiří; Kuldová, Karla; Oswald, Jiří; Hospodková, Alice
Fyzikální ústav, 2021

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.
2021 - 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, 2021

Radical-based tuning the surface functionality of MXene
Olshtrem, A.; Chertopalov, Sergii; Guselnikova, O.; Švorčík, V.; Lyutakov, O.
2021 - English
The family of MAX phases and their derivative MXenes are continuously growing in terms of both crystalline and composition varieties. MXenes are a new family of two-dimensional (2D) transition metal carbides, carbonitrides and nitrides, with a general formula Mn+1AXn, where n = 1–3, M denotes a transition metal, A is an element such as aluminum or silicon, and X is either carbon or nitrogen. Considering the various elemental composition possibilities, surface functional tunability, various magnetic orders, and large spin–orbit coupling, MXene can truly be considered as multifunctional materials that can be used to realize highly correlated phenomena. Keywords: chemical transformation; MXene; surface grafting; tuned functionalization Available at various institutes of the ASCR
Radical-based tuning the surface functionality of MXene

The family of MAX phases and their derivative MXenes are continuously growing in terms of both crystalline and composition varieties. MXenes are a new family of two-dimensional (2D) transition metal ...

Olshtrem, A.; Chertopalov, Sergii; Guselnikova, O.; Švorčík, V.; Lyutakov, O.
Fyzikální ústav, 2021

Effect of the substrate crystalline orientation on the surface morphology and boron incorporation into epitaxial diamond layers
Voves, J.; Pošta, A.; Davydova, Marina; Laposa, A.; Povolný, V.; Hazdra, P.; Lambert, Nicolas; Sedláková, Silvia; Mortet, Vincent
2021 - English
Epitaxial growth of diamond is critically important for the fabrication of diamond-based electronic devices. The emerging study of the epitaxial diamond growth on the (113) vicinal surfaces evidences highly needed high growth rates and low structural defects concentrations with both p- and n-type doping. In this work, we compare the morphology and dopant concentration incorporation of heavily boron-doped (113) epitaxial diamond layers with conventionally studied (100) and (111) epitaxial layers. Epitaxial layers were grown using resonance cavity Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) system. The surface morphology of epitaxial layers was studied by optical microscopy and atomic force microscopy, whereas the boron incorporation homogeneity was determined by Raman spectroscopy mapping. Keywords: diamond; epitaxy; defects; boron doping; Raman mapping Available at various institutes of the ASCR
Effect of the substrate crystalline orientation on the surface morphology and boron incorporation into epitaxial diamond layers

Epitaxial growth of diamond is critically important for the fabrication of diamond-based electronic devices. The emerging study of the epitaxial diamond growth on the (113) vicinal surfaces evidences ...

Voves, J.; Pošta, A.; Davydova, Marina; Laposa, A.; Povolný, V.; Hazdra, P.; Lambert, Nicolas; Sedláková, Silvia; Mortet, Vincent
Fyzikální ústav, 2021

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