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Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
Rezek, Bohuslav; Čermák, Jan; Varga, Marián; Tulic, S.; Skákalová, V.; Waitz, T.; Kromka, Alexander
2017 - English
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into formation and properties of GoD. The diamond films are coated by a nm thin sputtered Ni layer and heated to 900°C in a forming gas atmosphere (H2/Ar) to initiate catalytic thermal CVD process. The samples are cleaned from residual Ni after the growth process. We employ scanning electron microscopy, Raman micro-spectroscopy and Kelvin probe force microscopy to correlate material, structural, and electronic properties of graphene on diamond. We show how grain size and grain boundaries influence graphene growth and material and electronic properties. For instance we show that the grain boundaries (with non-diamond carbon phases) in diamond films have an important role. They influence the electronic properties and they are beneficial for forming graphene on diamond higher quality.
Keywords:
graphene; diamond; microscopy; micro-spectroscopy; electronic properties
Available at various institutes of the ASCR
Correlated microscopy of electronic and material properties of graphene grown on diamond thin films
In this work we compare growth of graphene on diamond thin films that enable large area processing. We use films with different crystal size and surface roughness to obtain deeper insight into ...
Performance of cement composites reinforced with surface-modified polypropylene micro-fibers
Antoš, J.; Dejdar, L.; Trejbal, J.; Prošek, Zdeněk
2017 - English
This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ratio equal to 0.4). Two polypropylene fiber types (micro-and macro-fibers) were used as randomly distributed and oriented reinforcement in volume amount of 2 %. The fibers were modified in the low-pressure inductively coupled cold oxygen plasma in order to enhance their surface interaction with the cement matrix. The investigated composite mechanical properties (load bearing capacity and response during loading) were examined indirectly by means of four-point bending mechanical destructive tests. A response of loaded samples containing treated fibers were compared to samples with reference fibers. Moreover, cracking behavior development was monitored using digital image correlation (DIC). This method enabled to record the micro-cracks system evaluation of both fiber reinforced samples.\n
Keywords:
cement composite; fiber reinforcement; polymeric fiber; surface modification; four-point bending; plasma treatment
Available at various institutes of the ASCR
Performance of cement composites reinforced with surface-modified polypropylene micro-fibers
This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ...
Structure and properties of DLC layers for industrial applications
Mates, Tomáš; Ledinský, Martin; Vetushka, Aliaksi; Pikna, Peter; Fejfar, Antonín; Marek, A.; Vyskočil, J.; Erichsen, J.; Dawah, P.
2017 - English
Diamond-like carbon (DLC) layers based on amorphous carbon are used for wide range of applications, mostly for mechanical protection of various industrial components. We examined DLC layers at micro- and nanoscale by two independent microscopic techniques: Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) with a good agreement. We compared DLC layers grown on steel substrate and Si wafer and found similarly structured clusters and a certain difference in the density of nucleation centres. The measurements of local mechanical properties by the AFM tip revealed that the Si wafer behaves as softer material compared to the growing DLC nanoclusters that also exhibit lower values in the map of the relative local friction coefficient. Finally, we observed changes in the Raman spectra of the DLC exposed to annealing at ambient conditions and found a gradual shift from the diamond phase to the graphite phase as a function of increasing temperature.
Keywords:
DLC; PACVD; AFM; SEM; Raman
Available at various institutes of the ASCR
Structure and properties of DLC layers for industrial applications
Diamond-like carbon (DLC) layers based on amorphous carbon are used for wide range of applications, mostly for mechanical protection of various industrial components. We examined DLC layers at micro- ...
Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition
Horažďovský, T.; Kovač, J.; Drbohlav, Ivo
2017 - English
Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of material research aimed at reducing the friction of the functional surfaces of titanium implants, and thus extending their lifetime to reoperation. An analysis of the chemical composition showed that the modified surface is composed of a carbon-based nanolayer, a mixed interface, and a nitrogen-enriched sublayer. Raman spectroscopy showed the DLC character of the carbon-based nanolayer with sp2 rich bonds. A TiN compound was detected by X-ray diffraction in the modified surface area.\n
Keywords:
nanolayer; friction; nanohardness
Available at various institutes of the ASCR
Characterization and tribological testing of a carbon-based nanolayer prepared by ion beam assisted deposition
Carbon-based nanolayers have been attracting much attention due to their excellent low-friction properties, their high hardness and their good wear resistance. In this work we present the results of ...
Miniaturized boron doped diamond film electrode for neuroblastoma biomarkers determination
Hrdlička, Vojtěch; Barek, J.; Navrátil, Tomáš; Taylor, Andrew
2017 - English
Cathodically pretreated miniaturized boron doped diamond film electrodewas successfully tested for the purposes of in-situ determination of neuroblastoma biomarkers after hollow-fibre based microextraction. Electrode was tested using K-3[Fe(CN)(6)] and vanillyl-mandelic acid as model substances. Limits of detection and determination are 2.2 and 6.6 mu mol L-1, respectively. Linear range was 2.2-100 mu molL(-1), repeatability 1.34% (n = 10).
Keywords:
biomarkers; boron doped diamond film; voltammetry
Available at various institutes of the ASCR
Miniaturized boron doped diamond film electrode for neuroblastoma biomarkers determination
Cathodically pretreated miniaturized boron doped diamond film electrodewas successfully tested for the purposes of in-situ determination of neuroblastoma biomarkers after hollow-fibre based ...
Analýza geometrických vlastností otvorů vrtaných v oxidové keramice pomocí pevnolátkového Nd:YaG laseru a kvazikontinuálního ytterbiového vláknového laseru
Řiháková, L.; Chmelíčková, Hana
2017 - Czech
Technická keramika jako např. Al2O3 v současné době nalezla uplatnění v mnoha odvětvích lidské činnosti díky jejím typickým vlastnostem.Tato práce je zaměřena na vrtání oxidové keramiky Al2O3 pomocí pevnolátkového Nd:YAG laseru a kvazikontinuálního (QCW) ytterbiového vláknového laseru s cílem vytvořit kvalitní otvory. Procesy vrtání těmito lasery byly porovnávány a byl zkoumán vliv parametrů použitých laserů na kvalitu a rozměry otvorů. Konkrétně se jednalo o studium vlivu energie pulsu, délky pulsu a počtu pulsů na průměr a kruhovitost vstupního a výstupního otvoru, „aspect ratio“ a přítomnost taveniny na okrajích otvoru. Pro oba lasery byly stanoveny optimální parametry procesu, při jejichž použití docházelo k vytvoření kvalitních otvorů bez nečistot a vzniku trhlin. Vytvořené otvory byly pozorovány a hodnoceny pomocí skenovacího konfokálního mikroskopu OLYMPUS LEXT 3100.\n Technical ceramic such as Al2O3 can be found in many fields of human activity due to its characteristic properties, like high hardness and brittleness, high thermal conductivity and wear, and chemical resistance. In this paper the percussion drilling of alumina ceramics was performed by Nd:YAG laser and quasi-continuous-wave ytterbium fiber laser with the aim to produce holes with high quality. Both processes were compared and the effects of the laser parameters on the holes quality and geometry were examined. Namely, the effects of wavelength, pulse energy, pulse length and number of pulses on the entrance and exit holes diameter and circularity, taper, aspect ratio and the presence of the melt were analyzed. The optimum parameters were found for both lasers ensuring the production of high duality holes without cracks or impurities. The holes were observed by scanning confocal microscope OLYMPUS LEXT 3100.
Keywords:
laser technology applied research
Available at various institutes of the ASCR
Analýza geometrických vlastností otvorů vrtaných v oxidové keramice pomocí pevnolátkového Nd:YaG laseru a kvazikontinuálního ytterbiového vláknového laseru
Technická keramika jako např. Al2O3 v současné době nalezla uplatnění v mnoha odvětvích lidské činnosti díky jejím typickým vlastnostem.Tato práce je zaměřena na vrtání oxidové keramiky Al2O3 pomocí ...
The intrinsic submicron ZnO thin films prepared by reactive magnetron sputtering
Remeš, Zdeněk; Stuchlík, Jiří; Purkrt, Adam; Chang, Yu-Ying; Jirásek, Vít; Štenclová, Pavla; Prajzler, V.; Nekvindová, P.
2017 - English
The DC reactive magnetron sputtering of metallic target in oxide atmosphere is a simple method of depositing the intrinsic (undoped) nanocrystalline layers of metal oxides. We have optimized the deposition of the intrinsic ZnO thin films with submicron thickness 50-500 nm on fused silica glass substrates and investigated the localized defect states below the optical absorption edge down to 0.01 % using photothermal deflection spectroscopy from UV to IR. We have shown that the defect density, the optical absorptance and the related optical attenuation in planar waveguides can be significantly reduced by annealing in air at 400 °C.
Keywords:
ZnO; reactive magnetron sputtering; plasma treatment; photothermal deflection spectroscopy; optical spectroscopy
Available at various institutes of the ASCR
The intrinsic submicron ZnO thin films prepared by reactive magnetron sputtering
The DC reactive magnetron sputtering of metallic target in oxide atmosphere is a simple method of depositing the intrinsic (undoped) nanocrystalline layers of metal oxides. We have optimized the ...
Hydrogen plasma treatment of ZnO thin films
Chang, Yu-Ying; Neykova, Neda; Stuchlík, Jiří; Purkrt, Adam; Remeš, Zdeněk
2017 - English
ZnO is an attractive wide band gap semiconductor with large exciton binding energy, high refractive index, high biocompatibility and diversety of nanostructure shapes which makes it suitable for many applications in the optoelectronic devices, optical sensors, and biosensors. We study the effect of hydrogen plasma treatment of the nominally undoped ZnO thin film deposited by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. The SEM images show that the crystal size increases with film thickness. We confirm, that the electrical conductivity significantly increases after hydrogen plasma treatment by 4 orders of magnitude. Moreover, the increase of the infrared optical absorption, related to free carrier concentration, was detected below the optical absorption edge by the photothermal deflection spectroscopy.\n
Keywords:
ZnO; reactive magnetron sputtering; hydrogen plasma treatment
Available at various institutes of the ASCR
Hydrogen plasma treatment of ZnO thin films
ZnO is an attractive wide band gap semiconductor with large exciton binding energy, high refractive index, high biocompatibility and diversety of nanostructure shapes which makes it suitable for many ...
Preparation of zinc oxide nanorods colloid from thin layers
Mičová, Júlia; Remeš, Zdeněk; Chang, Yu-Ying; Neykova, Neda
2017 - English
The interest in ZnO (zinc oxide) nanoparticles is increasing due to low cost of their processing as well as the ability of fabricating ZnO nanostructures with controllable morphology such as size, shape and orientation. Our choice of method of the preparation of the nanostructured thin ZnO layers is the hydrothermal growth of ZnO nanorods on glass substrates coated by the nucleation layer deposited by the reactive magnetron sputtering. We have developed and optimized conditions of the thin layer growth with controllable dimensions of nanorods followed by the ultrasound peeling. The colloid of ZnO nanorods was characterized by measuring the size of particles using the dynamic light scattering (DLS) and the scanning electron microscopy (SEM). We found that the dynamic light scattering (DLS) can’t be directly used for size evaluation of ZnO nanorods due to their non- sperical shape. \n
Keywords:
ZnO; method hydrothermal growth; thin layer; nanorods
Available at various institutes of the ASCR
Preparation of zinc oxide nanorods colloid from thin layers
The interest in ZnO (zinc oxide) nanoparticles is increasing due to low cost of their processing as well as the ability of fabricating ZnO nanostructures with controllable morphology such as size, ...
DLC/TI thin films properties prepared by hybrid laser technologies
Mikšovský, Jan; Jelínek, Miroslav; Písařík, Petr; Kocourek, Tomáš; Remsa, J.; Jurek, Karel
2017 - English
Layers of diamond-like carbon are usable in many fields of industry as well as in medicine. Many scientific groups have worked with different types of deposition techniques to prepare DLC layers with improved or unique properties. The DLC properties could be improved by various dopations. In this study, we focused on DLC layers doped by titanium, prepared by hybrid laser depositions. Two techniques were used: Dual pulse laser deposition (DualPLD) and pulse laser deposition in combination with magnetron sputtering (PLD/MS). Preliminary tests for morphology, wettability, adhesion, hardness, corrosion, friction and wearability were examined. DLC samples were prepared on Si(100) wafer and on Ti6Al4V alloy substrates with titanium concentration from pure up to 25 at.%. Friction of the prepared layers ranged from 0.09 to 0.18. The films exhibited very low wear for loads 1 N and 2 N.\n
Keywords:
DLC Friction; titanium doped; hybrid deposition
Available at various institutes of the ASCR
DLC/TI thin films properties prepared by hybrid laser technologies
Layers of diamond-like carbon are usable in many fields of industry as well as in medicine. Many scientific groups have worked with different types of deposition techniques to prepare DLC layers with ...
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