No (412)
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412
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Development of materials science in research and education. Book of abstracts of the 24th joint seminar
Kožíšek, Zdeněk; Nitsch, Karel
2014 - English
Topics: - Trends in development of materials research - Education of materials science at the universities - Information about the research programmes of individual institutions - Information on equipment for preparation and characterisation of materials - Results of materials science research
Keywords:
material sciences
Available at various institutes of the ASCR
Development of materials science in research and education. Book of abstracts of the 24th joint seminar
Topics: - Trends in development of materials research - Education of materials science at the universities - Information about the research programmes of individual institutions - Information on ...
Highly luminescent nanophosphors - new physics, technologies and applications
Nikl, Martin; Čuba, V.; Bárta, J.; Jarý, Vítězslav
2014 - English
The application of radiation synthesis in the manufacturing nanopowders of binary and ternary oxide nanophosphors is reviewed. Technological routes are described: irradiation of specific solutions containing soluble metal salts and OH radical scavenger by UV or ionizing radiation results in the formation of finely dispersed solid phase which is separated from the solution and subsequently converted by further thermal treatment into crystalline nanopowders with typical dimension of grains of several tens of nanometers. Doped ZnO, Y2O3, Y3Al5O12, Lu3Al5O12 and Gd3(Ga,Al)5O12 nanophosphors were prepared and their luminescence and scintillation characteristics were measured. In the photoluminescence decay of doped garnets the distinct effect of nanosized grains was found consisting in the slowing-down of the decay due to the change of effective refractive index.
Keywords:
scintillator; phosphor; radiation method; nanocrystals; garnet; ZnO; Y.sub.2./sub.O.sub.3./sub.; rare earth dopants
Available at various institutes of the ASCR
Highly luminescent nanophosphors - new physics, technologies and applications
The application of radiation synthesis in the manufacturing nanopowders of binary and ternary oxide nanophosphors is reviewed. Technological routes are described: irradiation of specific solutions ...
Electronic excitation energy transfer between quasi-zero-dimensional systems
Král, Karel; Menšík, Miroslav
2014 - English
Electronic excitation energy transfer is studied theoretically within a prototype system of quantum dots using the excitonic representation of the electronic states of two quasi-zero dimensional subsystems, between which the excitation energy is transferred in a process treated as an irreversible kinetic phenomenon. The electron-phonon interaction is used to circumvent the energy conservation problem, especially when considering the uphill and downhill excitation transfer processes. The theory is studied upon utilizing a simplified model of two interacting quantum dots, both coupled to their environment. The theoretical approach is documented by numerical calculations. The results could be relevant to various cases of the electronic excitation energy transfer between quasi zero dimensional nanostructures.
Keywords:
quantum dots; energy transfer; electron-phonon interaction
Available at various institutes of the ASCR
Electronic excitation energy transfer between quasi-zero-dimensional systems
Electronic excitation energy transfer is studied theoretically within a prototype system of quantum dots using the excitonic representation of the electronic states of two quasi-zero dimensional ...
Algicidal properties nanofibrous fabrics doped by metals
Ryparová, Pavla; Wasserbauer, R.; Rácová, Z.; Demo, Pavel; Tesárek, Pavel
2014 - English
The paper presents a novel protection against algae by nanofiber fabrics doped with metal ions. Nanofiber textiles were prepared by electrospinning on the Nanospider LB 500 device, equipped with cylindrical electrodes of a length 600 mm and electrode distance about 140 mm. The produced nanofiber textiles had a specific weight between 2 and 4 g/m2. The entire surface was covered with algae commonly accompanied by bacteria. The sample had placed in the middle of circular dishes having the diameter 20 mm. The cultivation took place at light environment in common laboratory conditions. Algicidal effect was evaluated as the resulting halo size and quality around the sample. The PVA treated sample had not produce any halo effect, unlike the samples with the addition of metal salts (AgNO3, CuSO4 center dot 5H(2)O) that exhibited the halo effect dependent on the concentration the salts, usually ranging from 0.3-2 mm, giving the evidence about their algicidal properties.\n
Keywords:
algicidal properties; polymer nanofibers; dispersed nanoparticles; metal nanoparticles; stone
Available at various institutes of the ASCR
Algicidal properties nanofibrous fabrics doped by metals
The paper presents a novel protection against algae by nanofiber fabrics doped with metal ions. Nanofiber textiles were prepared by electrospinning on the Nanospider LB 500 device, equipped with ...
Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
Domonkos, Mária; Ižák, Tibor; Stolcova, L.; Proška, J.; Kromka, Alexander
2014 - English
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with diameter of 471 nm was used as the primary template. The PM templates were processed in two different RIE systems: (i) capacitively coupled radiofrequency plasma (CCP) and (ii) dual plasma system which combines CCP and pulsed linear-antenna microwave plasma (PLAMWP). The influence of process conditions on the PM geometry was systematically studied by scanning electron microscopy (SEM). It was found out that choosing optimal parameters results in a tunable diameter of PM with various shapes (from spheres to pyramid-like structures) while keeping their periodic hexagonal ordering.
Keywords:
nanosphere lithography; reactive ion etching; pulsed linear-antenna microwave plasma; polystyrene microspheres; Langmuir-Blodgett monolayers
Available at various institutes of the ASCR
Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with ...
Safety aspects of usage of flammable and toxic gases in high power laser accelerator experiments
Procházka, Petr; Prokůpek, J.; Perales, B.
2014 - English
High power laser accelerators are promising technologies that can effectively decrease the space and potentially cost of the particle acceleration experiments. For many of them there is a technical demand to use flammable and toxic gases as targets for lasers or for accelerated particles. Their usage, however, brings many challenges for design of the technology and safety management system of the facility.
Keywords:
high power laser; accelerator
Available at various institutes of the ASCR
Safety aspects of usage of flammable and toxic gases in high power laser accelerator experiments
High power laser accelerators are promising technologies that can effectively decrease the space and potentially cost of the particle acceleration experiments. For many of them there is a technical ...
Comparative study on functionalization of NCD films with amine groups
Artemenko, Anna; Kozak, Halyna; Stuchlík, Jiří; Biederman, H.; Kromka, Alexander
2014 - English
Two plasma-based processes for functionalization of oxygen or hydrogen terminated NCD surfaces with amino groups were compared. The first process was based on deposition of thin (8 nm) amine containing plasma polymer by RF magnetron sputtering of Nylon target in Ar/N-2 working gas mixture. RF plasma treatment in NH3 for 10 minutes was used in the second process. The properties of NCD films before and after amination were characterized by scanning electron microscopy (SEM), wettability measurements, spectral ellipsometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and current-voltage (I-V) measurements. The presence of nitrogen (and thus amino groups) on the surface was confirmed by XPS measurements in both cases. The obtained results indicated that NCD surface functionalization from amine containing plasma polymer by RF magnetron sputtering is an alternative technological solution for successful functionalization of diamond surfaces for biosensor applications.
Keywords:
diamond; amino functionalization; XPS; surface conductivity
Available at various institutes of the ASCR
Comparative study on functionalization of NCD films with amine groups
Two plasma-based processes for functionalization of oxygen or hydrogen terminated NCD surfaces with amino groups were compared. The first process was based on deposition of thin (8 nm) amine ...
Model of static recrystallization in the coarse-grained B2 iron aluminide
Schindler, I.; Šumšal, V.; Kopeček, Jaromír; Kawulok, P.; Jozwik, P.; Rusz, S.; Kawulok, R.; Opěla, P.
2014 - English
Microstructure of the laboratory castings made from Fe-40at.%Al-Zr-B alloy was homogenized by the multipass hot rolling in protective capsules and subsequent lannealing. Based on the isothermal hot compression tests and EBSD analysis, the sufficiently accurate model describing the static recrystalization kinetics of the such prepared coarse-grained B2 iron aluminide after strain 0.2 was developed. The independent variables in this model are temperature of deformation as well as annealing time equal to the deformation temperature. Unexpected effect of the previous strain value on the static softening was observed. Static recrystallization begins relatively easy in the studied alloy in the whole range of testing temperatures (900-1100 °C), but a very long-term annealing is quite necessary for the complete course of recrystallization.\n
Keywords:
iron aluminide; hot compression test; microstructure; EBSD; static recrystallization
Available at various institutes of the ASCR
Model of static recrystallization in the coarse-grained B2 iron aluminide
Microstructure of the laboratory castings made from Fe-40at.%Al-Zr-B alloy was homogenized by the multipass hot rolling in protective capsules and subsequent lannealing. Based on the isothermal hot ...
Nanopositioning with detection of a standing wave
Holá, M.; Hrabina, J.; Číp, O.; Fejfar, Antonín; Stuchlík, Jiří; Kočka, Jan; Oulehla, J.; Lazar, J.
2014 - English
A measuring technique is intended for displacement and position sensing over a limited range with detection of standing-wave pattern inside of a passive Fabry-Perot cavity. In this concept we consider locking of the laser optical frequency and the length of the Fabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows stabilizing wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneity. Detection of the interference maxima and minima within the Fabry-Perot cavity along the beam axis has been tested and proven with a low loss transparent photodetector with very low reflectivity. The transparent photodetector is based on a thin polycrystalline silicon layer. Reduction of losses was achieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.
Keywords:
nanometrology; nanopositioning; Fabry-Perot cavity; standing wave; interferometry
Available at various institutes of the ASCR
Nanopositioning with detection of a standing wave
A measuring technique is intended for displacement and position sensing over a limited range with detection of standing-wave pattern inside of a passive Fabry-Perot cavity. In this concept we consider ...
Characterisation of InAs/GaAs quantum dots by high resolution transmission electron microscopy
Zíková, Markéta; Hospodková, Alice; Pangrác, Jiří; Hulicius, Eduard; Komninou, Ph.; Kioseoglou, J.
2014 - English
The InAs/GaAs quantum dots (QDs) covered by GaAsSb strain reducing layer (SRL) have suitable properties for various applications. The GaAsSb SRL covering InAs QDs is used to improve the structure growth and the final parameters like QD density, QD size or photoluminesence. To obtain high-quality structure with required properties, the structure growth and final structure have to be deeply studied. Since the QDs and SRL system is surrounded by GaAs, the high resolution transmission electron microscopy (HRTEM) measurement was used to reveal the real material arrangement in a prepared sample. In this work we will discuss the results of following HRTEM measurements: flatness and thickness of prepared layers, QD size, atomic arrangement and composition of GaAsSb layer.
Keywords:
quantum dot; InAs; GaAsSb; high resolution transmission electron microscopy
Available at various institutes of the ASCR
Characterisation of InAs/GaAs quantum dots by high resolution transmission electron microscopy
The InAs/GaAs quantum dots (QDs) covered by GaAsSb strain reducing layer (SRL) have suitable properties for various applications. The GaAsSb SRL covering InAs QDs is used to improve the structure ...
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