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236 results on '"Polonskyi, Oleksandr"'

54. Superhydrophobic 3D Porous PTFE/TiO2 Hybrid Structures

Author

Aktas, Oral Cenk, primary, Schröder, Stefan, additional, Veziroglu, Salih, additional, Ghori, Muhammed Zubair, additional, Haidar, Ayman, additional, Polonskyi, Oleksandr, additional, Strunskus, Thomas, additional, Gleason, Karen, additional, and Faupel, Franz, additional

Published
2019
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55. Cauliflower-like CeO2–TiO2hybrid nanostructures with extreme photocatalytic and self-cleaning properties

Author

Veziroglu, Salih, primary, Röder, Katharina, additional, Gronenberg, Ole, additional, Vahl, Alexander, additional, Polonskyi, Oleksandr, additional, Strunskus, Thomas, additional, Rubahn, Horst-Günter, additional, Kienle, Lorenz, additional, Adam, Jost, additional, Fiutowski, Jacek, additional, Faupel, Franz, additional, and Aktas, Oral Cenk, additional

Published
2019
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56. Magnetron-sputtered copper nanoparticles : lost in gas aggregation and found by in situ X-ray scattering

Author

Kousal, Jaroslav, Shelemin, Artem, Schwartzkopf, Matthias, Polonskyi, Oleksandr, Hanus, Jan, Solar, Pavel, Vaidulych, Mykhailo, Nikitin, Daniil, Pleskunov, Pavel, Krtous, Zdenek, Strunskus, Thomas, Faupel, Franz, Roth, Stephan V., Biederman, Hynek, Choukourov, Andrei, Kousal, Jaroslav, Shelemin, Artem, Schwartzkopf, Matthias, Polonskyi, Oleksandr, Hanus, Jan, Solar, Pavel, Vaidulych, Mykhailo, Nikitin, Daniil, Pleskunov, Pavel, Krtous, Zdenek, Strunskus, Thomas, Faupel, Franz, Roth, Stephan V., Biederman, Hynek, and Choukourov, Andrei

Abstract

Magnetron discharge in a cold buffer gas represents a liquid-free approach to the synthesis of metal nanoparticles (NPs) with tailored structure, chemical composition and size. Despite a large number of metal NPs that were successfully produced by this method, the knowledge of the mechanisms of their nucleation and growth in the discharge is still limited, mainly because of the lack of in situ experimental data. In this work, we present the results of in situ Small Angle X-ray Scattering measurements performed in the vicinity of a Cu magnetron target with Ar used as a buffer gas. Condensation of atomic metal vapours is found to occur mainly at several mm distance from the target plane. The NPs are found to be captured preferentially within a region circumscribed by the magnetron plasma ring. In this capture zone, the NPs grow to the size of 90 nm whereas smaller ones sized 10-20 nm may escape and constitute a NP beam. Time-resolved measurements of the discharge indicate that the electrostatic force acting on the charged NPs may be largely responsible for their capturing nearby the magnetron., QC 20181210

Published
2018
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57. Enhancing composition control of alloy nanoparticles from gas aggregation source by in operando optical emission spectroscopy.

Author

Drewes, Jonas, Vahl, Alexander, Carstens, Niko, Strunskus, Thomas, Polonskyi, Oleksandr, and Faupel, Franz

Subjects
EMISSION spectroscopy, OPTICAL spectroscopy, LIGHT sources, ALLOYS, NANOPARTICLES, SILVER alloys
Abstract

The use of multicomponent targets allows the gas‐phase synthesis of a large variety of alloy nanoparticles (NPs) via gas aggregation sources. However, the redeposition of sputtered material impacts the composition of alloy NPs, as demonstrated here for the case of AgAu alloy NPs. To enable NPs with tailored Au fractions, in operando control over the composition of the NPs is in high demand. We suggest the use of optical emission spectroscopy as a versatile diagnostic tool to determine and control the composition of the NPs. A strong correlation between operating pressure, intensity ratio of Ag and Au emission lines, and the obtained NP compositions is observed. This allows precise in operando control of alloy NP composition obtained from multicomponent targets. [ABSTRACT FROM AUTHOR]

Published
2021
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59. Nucleation and Growth of Magnetron‐Sputtered Ag Nanoparticles as Witnessed by Time‐Resolved Small Angle X‐Ray Scattering.

Author

Shelemin, Artem, Pleskunov, Pavel, Kousal, Jaroslav, Drewes, Jonas, Hanuš, Jan, Ali‐Ogly, Suren, Nikitin, Daniil, Solař, Pavel, Kratochvíl, Jiří, Vaidulych, Mykhailo, Schwartzkopf, Matthias, Kylián, Ondřej, Polonskyi, Oleksandr, Strunskus, Thomas, Faupel, Franz, Roth, Stephan V., Biederman, Hynek, and Choukourov, Andrei

Subjects
SMALL-angle scattering, X-ray scattering, SMALL-angle X-ray scattering, DISCONTINUOUS precipitation, TOROIDAL plasma, MAGNETRON sputtering, NANOPARTICLES
Abstract

Kinetic aspects of the synthesis of Ag nanoparticles (NPs) by magnetron sputtering are studied by in situ and time‐resolved small angle X‐ray scattering (SAXS). Part of the NPs are found to become confined within a capture zone at 1–10 mm from the surface of the target and circumscribed by the plasma ring. Three regimes of the NP growth are identified: 1) early growth at which the average NP diameter rapidly increases to 90 nm; 2) cycling instabilities at which the SAXS signal periodically fluctuates either due to expelling of large NPs from the capture zone or due to the axial rotation of the NP cloud; and 3) steady‐state synthesis at which stable synthesis of the NPs is achieved. The NP confinement within the capture zone is driven by the balance of forces, the electrostatic force being dominant. On reaching the critical size, large NPs acquire an excessive charge and become expelled from the capture zone via the electrostatic interactions. As a result, significant NP deposits are formed on the inner walls of the aggregation chamber as well as in the central area of the target. [ABSTRACT FROM AUTHOR]

Published
2020
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63. Tuning doping and surface functionalization of columnar oxide films for volatile organic compound sensing: experiments and theory

Author

Postica, Vasile, primary, Vahl, Alexander, additional, Strobel, Julian, additional, Santos-Carballal, David, additional, Lupan, Oleg, additional, Cadi-Essadek, Abdelaziz, additional, de Leeuw, Nora H., additional, Schütt, Fabian, additional, Polonskyi, Oleksandr, additional, Strunskus, Thomas, additional, Baum, Martina, additional, Kienle, Lorenz, additional, Adelung, Rainer, additional, and Faupel, Franz, additional

Published
2018
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64. Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering

Author

Kousal, Jaroslav, primary, Shelemin, Artem, additional, Schwartzkopf, Matthias, additional, Polonskyi, Oleksandr, additional, Hanuš, Jan, additional, Solař, Pavel, additional, Vaidulych, Mykhailo, additional, Nikitin, Daniil, additional, Pleskunov, Pavel, additional, Krtouš, Zdeněk, additional, Strunskus, Thomas, additional, Faupel, Franz, additional, Roth, Stephan V., additional, Biederman, Hynek, additional, and Choukourov, Andrei, additional

Published
2018
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66. Vacuum thermal degradation of poly(ethylene oxide)

Author

Choukourov, Andrei, Grinevich, Andrey, Polonskyi, Oleksandr, Hanus, Jan, Kousal, Jaroslav, Slavinska, Danka, and Biederman, Hynek

Subjects
Decomposition (Chemistry) -- Research, Ethylene oxide -- Properties, Ethylene oxide -- Research, Vacuum -- Research, Chemicals, plastics and rubber industries
Published
2009

69. Nanosensors: Localized Synthesis of Iron Oxide Nanowires and Fabrication of High Performance Nanosensors Based on a Single Fe2 O3 Nanowire (Small 16/2017)

Author

Lupan, Oleg, primary, Postica, Vasile, additional, Wolff, Niklas, additional, Polonskyi, Oleksandr, additional, Duppel, Viola, additional, Kaidas, Victor, additional, Lazari, Eugen, additional, Ababii, Nicolai, additional, Faupel, Franz, additional, Kienle, Lorenz, additional, and Adelung, Rainer, additional

Published
2017
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72. Morphology and optoelectronics at Metal-Polymer-Interfaces during Sputter Deposition

Author

Schwartzkopf, Matthias, Santoro, Gonzalo, Polonskyi, Oleksandr, Hinz, Alexander, Metwalli, Ezzeldin, Yao, Yuan, Strunskus, Thomas, Faupel, Franz, Müller-Buschbaum, Peter, and Roth, Stephan V.

Abstract

Oral presentation given at the DGP Verhandlungen, held in Berlin (Germany) on March 15-20th, 2015., The reproducible low-cost fabrication of functional polymer-metal-nanocomposites with tailored optoelectronic properties remains a major issue in applied nanotechnology. In order to obtain full control over the nanostructural evolution at the metal-polymer interface and its impact on optoelectronic properties, we employed the combination of in-situ time-resolved GISAXS [1] with in-situ surface differential reflectivity spectrometry during sputter deposition of gold on thin polystyrene films. We correlate the evolution of the metallic layer morphology with changes in the key scattering. This enabled us to identify the different growth regimes with their specific thresholds and permits a better understanding of the growth kinetics of gold clusters on polymer substrates. Our study opens up the opportunity to improve nanofabrication of tailored metal-polymer nanostructures for organic electronics like photovoltaic applications and plasmonic-based technologies.

Published
2015

73. Investigation of the metallization of P(VDF-TrFE) with gold by RF-sputter deposition

Author

Hinz, Alexander, Polonskyi, Oleksandr, Schwartzkopf, Matthias, Santoro, Gonzalo, Metwalli, Ezzeldin, Yao, Yuan, Strunskus, Thomas, Faupel, Franz, Roth, Stephan V., and Müller-Buschbaum, Peter

Abstract

Poster presented at the DGP Verhandlungen, held in Berlin (Germany) on March 15-20th, 2015., Although it is well established in industry and important for many applications the sputter deposition of metals onto organic surfaces is yet to be completely understood. Due to the inherent complexity (e.g. bombardment of the organic surfaces by energetic ions) of the sputtering process the basic mechanisms determining the final microstructure are still to be identified. The complexity of sputter deposition and the post-deposition changes which are to be expected necessitate the use of in-situ methods. In-situ grazing incidence small angle scattering (GISAXS) has been used to extract structural information with high spatial and temporal resolution from a growing Au-film deposited via RF-sputter deposition onto a P(VDF-TrFE)-film. The Au-P(VDF-TrFE) system has been chosen as a model system of a relatively inert metal-polymer pair. Analysis of the GISAXS data yields information about the morphology of the growing Au-film. Comparing these results to simulated scattering data provides further information about the basic growth mechanisms acting at different stages of the growth of the metal film.

Published
2015

74. Real-Time Monitoring of Morphology and Optical Properties during Sputter Deposition for Tailoring Metal–Polymer Interfaces

Author

Schwartzkopf, Matthias, Santoro, Gonzalo, Brett, Calvin J., Rothkirch, André, Polonskyi, Oleksandr, Hinz, Alexander, Metwalli, Ezzeldin, Yao, Yuan, Strunskus, Thomas, Faupel, Franz, Müller-Buschbaum, Peter, Roth, Stephan V., China Scholarship Council, and German Research Foundation

Subjects
Metal-polymer nanocomposites, ddc:540, Gold cluster growth kinetics, Sputter deposition, UV/vis specular reflectance spectroscopy, in situ GISAXS
Abstract

The reproducible low-cost fabrication of functional metal-polymer nanocomposites with tailored optoelectronic properties for advanced applications remains a major challenge in applied nanotechnology. To obtain full control over the nanostructural evolution at the metal-polymer interface and its impact on optoelectronic properties, we employed combined in situ time-resolved microfocus grazing incidence small angle X-ray scattering (μGISAXS) with in situ UV/vis specular reflectance spectroscopy (SRS) during sputter deposition of gold on thin polystyrene films. On the basis of the temporal evolution of the key scattering features in the real-time μGISAXS experiment, we directly observed four different growth regimes: nucleation, isolated island growth, growth of larger aggregates via partial coalescence, and continuous layer growth. Moreover, their individual thresholds were identified with subnanometer resolution and correlated to the changes in optical properties. During sputter deposition, a change in optical reflectivity of the pristine gray-blue PS film was observed ranging from dark blue color due to the presence of isolated nanoclusters at the interface to bright red color from larger Au aggregates. We used simplified geometrical assumptions to model the evolution of average real space parameters (distance, size, density, contact angle) in excellent agreement with the qualitative observation of key scattering features. A decrease of contact angles was observed during the island-to-percolation transition and confirmed by simulations. Furthermore, a surface diffusion coefficient according to the kinetic freezing model and interfacial energy of Au on PS at room temperature were calculated based on a real-time experiment. The morphological characterization is complemented by X-ray reflectivity, optical, and electron microscopy. Our study permits a better understanding of the growth kinetics of gold clusters and their self-organization into complex nanostructures on polymer substrates. It opens up the opportunity to improve nanofabrication and tailoring of metal-polymer nanostructures for optoelectronic applications, organic photovoltaics, and plasmonic-enhanced technologies (Figure Presented)., The authors acknowledge the Deutsche Forschungsgemeinschaft for funding under projects RO 4638/1-1, FA 234/23-1, and MU 1487/18-1. Y. Yao acknowledges the China Scholarship Council (CSC).

Published
2015
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75. Photodeposition of Au Nanoclusters for Enhanced Photocatalytic Dye Degradation over TiO2Thin Film

Author

Veziroglu, Salih, Obermann, Anna-Lena, Ullrich, Marie, Hussain, Majid, Kamp, Marius, Kienle, Lorenz, Leißner, Till, Rubahn, Horst-Günter, Polonskyi, Oleksandr, Strunskus, Thomas, Fiutowski, Jacek, Es-Souni, Mohammed, Adam, Jost, Faupel, Franz, and Aktas, Oral Cenk

Abstract

Au nanoparticle (NP) decorated heterogeneous TiO2catalysts are known to be effective in the degradation of various organic pollutants. The photocatalytic performance of such Au–TiO2structures remarkably depends on the size, morphology, and surface coverage of the Au NPs decorating TiO2. Here we propose an effective way of preparing a highly active Au nanocluster (NC) decorated TiO2thin film by a novel photodeposition method. By altering the solvent type as well as the illumination time, we achieved well-controlled surface coverage of TiO2by Au NCs, which directly influences the photocatalytic performance. Here the Au NCs coverage affects both the electron store capacity and the optical absorption of the hybrid Au–TiO2system. At low surface coverage, 19.2–29.5%, the Au NCs seem to enhance significantly the optical adsorption of TiO2at UV wavelengths which therefore leads to a higher photocatalytic performance.

Published
2020
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77. Low-Temperature Solution Synthesis of Au-Modified ZnO Nanowires for Highly Efficient Hydrogen Nanosensors

Author

Lupan, Oleg, Postica, Vasile, Wolff, Niklas, Su, Jun, Labat, Frédéric, Ciofini, Ilaria, Cavers, Heather, Adelung, Rainer, Polonskyi, Oleksandr, Faupel, Franz, Kienle, Lorenz, Viana, Bruno, and Pauporté, Thierry

Abstract

In this research, the low-temperature single-step electrochemical deposition of arrayed ZnO nanowires (NWs) decorated by Au nanoparticles (NPs) with diameters ranging between 10 and 100 nm is successfully demonstrated for the first time. The AuNPs and ZnO NWs were grown simultaneously in the same growth solution in consideration of the HAuCl4concentration. Optical, structural, and chemical characterizations were analyzed in detail, proving high crystallinity of the NWs as well as the distribution of Au NPs on the surface of zinc oxide NWs demonstrated by transmission electron microscopy. Individual Au NPs-functionalized ZnO NWs (Au-NP/ZnO-NWs) were incorporated into sensor nanodevices using an focused ion bean/scanning electron microscopy (FIB/SEM) scientific instrument. The gas-sensing investigations demonstrated excellent selectivity to hydrogen gas at room temperature (RT) with a gas response, Igas/Iair, as high as 7.5–100 ppm for Au-NP/ZnO-NWs, possessing a AuNP surface coverage of ∼6.4%. The concentration of HAuCl4in the electrochemical solution was observed to have no significant impact on the gas-sensing parameters in our experiments. This highlights the significant influence of the total Au/ZnO interfacial area establishing Schottky contacts for the achievement of high performances. The most significant performance of H2response was observed for gas concentrations higher than 500 ppm of H2in the environment, which was attributed to the surface metallization of ZnO NWs during exposure to hydrogen. For this case, an ultrahigh response of about 32.9 and 47 to 1000 and 5000 ppm of H2was obtained, respectively. Spin-polarized periodic density functional theory calculations were realized on Au/ZnO bulk and surface-functionalized models, validating the experimental hypothesis. The combination of H2gas detection at RT, ultralow power consumption, and reduced dimensions makes these micro-nanodevices excellent candidates for hydrogen gas leakage detection, including hydrogen gas monitoring (less than 1 ppm).

Published
2024
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83. Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties

Author

Polonskyi, Oleksandr, Biederman, Hynek, Novák, Stanislav, and Kadlec, Stanislav

Subjects
oxid kovu, nanoklastry, nanokompozitní tenká vrstva, metal oxide, plazmový polymer, nanocomposite thin film, plasma polymer, nanoclusters
Abstract

Title: Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties Author: Oleksandr Polonskyi Department: Department of Macromolecular Physics, MFF UK Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This thesis is devoted to a study of nanocomposite films Al (Al oxide)/plasma polymer prepared by various techniques using magnetron sputtering, plasma polymerization and cluster beam deposition. The formation and deposition of metal/metal oxide nanoclusters using a gas aggregation cluster source (GAS) was also considered. The role of low concentration of oxygen in the aggregation gas on the process of Al and Ti cluster deposition was studied. Properties of the nanoclusters and nanocomposite films were characterized by various techniques. Morphology of the nanocomposites was examined by AFM, TEM or HRTEM and SEM. Elemental analysis and chemical composition of the films were studied by XPS and FTIR. Optical characterization of the prepared films was done by UV-Vis spectroscopy and spectroscopic ellipsometry. It has been shown that using GAS nanocomposite Al(AlxOy)/C:H may be prepared. Keywords: nanocomposite thin film, plasma polymer, metal...

Published
2012

84. Real-Time Monitoring of Morphology and Optical Properties during Sputter Deposition for Tailoring Metal–Polymer Interfaces

Author

Schwartzkopf, Matthias, primary, Santoro, Gonzalo, additional, Brett, Calvin J., additional, Rothkirch, André, additional, Polonskyi, Oleksandr, additional, Hinz, Alexander, additional, Metwalli, Ezzeldin, additional, Yao, Yuan, additional, Strunskus, Thomas, additional, Faupel, Franz, additional, Müller-Buschbaum, Peter, additional, and Roth, Stephan V., additional

Published
2015
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85. Photovoltage method for the research of CdS and ZnO nanoparticles and hybrid MEH-PPV/nanoparticle structures

Author

Toušková, Jana, Toušek, Jiří, Rohovec, Jan, Růžička, Aleš, Polonskyi, Oleksandr, Urbánek, Pavel, Kuřitka, Ivo, Toušková, Jana, Toušek, Jiří, Rohovec, Jan, Růžička, Aleš, Polonskyi, Oleksandr, Urbánek, Pavel, and Kuřitka, Ivo

Abstract

The paper demonstrates an application of photovoltaic effect in the research of nanomaterials and hybrid structures of polymers with nanoparticles. Photovoltage (PV) measurement was utilized for estimating the size of CdS and ZnO nanoparticles and diagnostics of hybrid structures with poly[2-methoxy-5-(2- ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), namely nano-CdS/MEH-PPV and nano-ZnO/MEH-PPV. CdS average nanocrystal diameters 4.0 and 4.8 nm were calculated from the onset values of energies corresponding to the steep increase in the PV signals using the effective mass model. The range of size of ZnO particles was from about 5 up to 50 nm. Nanoparticle distribution obtained by transmission electron microscopy (TEM) measurements shows that the calculated diameters agree fairly well with the size of nanoparticles with the highest occurrence. The PV spectrum represents a sum of the spectra corresponding to the various nanoparticle sizes. The distribution of the nanoparticles was also obtained by a simple mathematical treatment of the PV spectra, and agreement with the results of TEM was found. PV and TEM measurements were performed on commercial CdS and ZnO nanoparticles and on CdS nanoparticles prepared in our laboratory. We employ triethanolamine as a protective agent to cover the surface of CdS nanoparticles. Nano-CdS/MEH-PPV and nano-ZnO/MeH-PPV hybrid structures were prepared, and influence of the particles on charge transport was shown by the PV spectra measurements. © 2014 Springer Science+Business Media.

Published
2014

88. Versatile Growth of Freestanding Orthorhombic α-Molybdenum Trioxide Nano- and Microstructures by Rapid Thermal Processing for Gas Nanosensors

Author

Lupan, Oleg, primary, Cretu, Vasilii, additional, Deng, Mao, additional, Gedamu, Dawit, additional, Paulowicz, Ingo, additional, Kaps, Sören, additional, Mishra, Yogendra Kumar, additional, Polonskyi, Oleksandr, additional, Zamponi, Christiane, additional, Kienle, Lorenz, additional, Trofim, Viorel, additional, Tiginyanu, Ion, additional, and Adelung, Rainer, additional

Published
2014
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93. Morphology of Titanium Nanocluster Films Prepared by Gas Aggregation Cluster Source

Author

Drábik, Martin, primary, Choukourov, Andrei, additional, Artemenko, Anna, additional, Kousal, Jaroslav, additional, Polonskyi, Oleksandr, additional, Solař, Pavel, additional, Kylián, Ondřej, additional, Matoušek, Jindřich, additional, Pešička, Josef, additional, Matolínová, Iva, additional, Slavínská, Danka, additional, and Biederman, Hynek, additional

Published
2011
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97. Plasma Process. Polym. 1/2010

Author

Choukourov, Andrei, primary, Solar, Pavel, additional, Polonskyi, Oleksandr, additional, Hanus, Jan, additional, Drabik, Martin, additional, Kylian, Ondrej, additional, Pavlova, Ewa, additional, Slavinska, Danka, additional, and Biederman, Hynek, additional

Published
2010
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