Viliam Vretenár

Slovak University of Technology in Bratislava

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Viera Skákalová

University of Vienna

Vlastimil Boháč

Slovak Academy of Sciences

ĽK

Ľ. Kubičár

Slovak Academy of Sciences

Mário Kotlár

Slovak University of Technology in Bratislava

Martin Hulman

Institute of Electrical Engineering of the Slovak Academy of Sciences

Peter Dieška

Slovak University of Technology in Bratislava

Peter Kotrusz

Danubia NanoTech (Slovakia)

Alexander Kromka

Czech Academy of Sciences, Institute of Physics

MČ

Mária Čaplovičová

Slovak University of Technology in Bratislava

VŠ

Vladimír Štofanik

Institute of Physics of the Slovak Academy of Sciences

Cooperative Institutions

Slovak Academy of Sciences

Czech Academy of Sciences, Institute of Physics

Slovak University of Technology in Bratislava

Comenius University Bratislava

Center for Physical Sciences and Technology

Institute of Chemistry of the Slovak Academy of Sciences

Institute of Electrical Engineering of the Slovak Academy of Sciences

Technische Universität Ilmenau

Czech Academy of Sciences

Czech Technical University in Prague

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HFCVD growth of various carbon nanostructures on SWCNT paper controlled by surface treatment

physica status solidi (b) (2012)

M. Varga Mário Kotlár Viliam Vretenár Tibor Ižák Martin Ledinský

Abstract In this article, we investigate the nanocomposite material formation, particularly the deposition of nanocrystalline diamond and carbon nanowalls (CNWs) on single‐wall carbon nanotubes buckypaper (BP). One part of the buckypaper substrate was nucleated by nanodiamond powder. The growth was carried out in a hot filament chemical vapor deposition (HFCVD) system. Contact angle measurements, scanning electron microscopy, and Raman spectroscopy were used for the surface morphology analysis and characterization of carbon phases. Due to a different surface pretreatment, different carbon nanostructures were formed: diamond film was grown on the nucleated BP area; non‐treated area of the BP was covered with a dense field of CNWs. Covering a part of the BP surface prevented an access of the HF‐plasma and so the growth of any carbon structures.

Buckypaper

Nanodiamond

Carbon fibers

Nanocrystalline material

10.1002/pssb.201200123

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Citations (13)

Thermophysical Properties of Electrically Conductive SiC–(Nb,Ti–C)ss-Based Cermets

International Journal of Thermophysics (2009)

Miroslav Balog Viliam Vretenár I. Vávra Jiaming Zhang M.A. Crimp

Cermet

10.1007/s10765-009-0688-x

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Bacterial response to nanodiamonds and graphene oxide sheets

physica status solidi (b) (2016)

Alexander Kromka Jaroslav Jíra Pavla Štenclová Vítězslav Kříha Halyna Kozak

Carbon nanomaterials such as nanodiamond (ND) and graphene oxide (GO) attract increasing attention for biomedical applications due their unique and adjustable properties. Here we report on antibacterial activity of NDs and GO as evaluated by bacterial colony counting. ND and GO were used in oxidized (O‐ND, GO) or reduced (H‐ND, rGO) forms. ND or GO are mixed in Mueller–Hinton (MH) broth with Escherichia coli at the concentration of 1 mg ml −1 . The resulting suspensions were cultivated for 5 and 24 h at 37 °C in a shaker. After each period, a sample of the suspension was spread on the MH agar and cultivated for 24 h at 37° C. The effect of nanomaterials on colony forming ability (CFA) of E. coli was evaluated and compared with the negative control sample. The most noticeable effect was that after 5 h H‐ND decreased the CFA of E. coli in the MH broth by 60% and GO by 50%. After 24 h, H‐ND decreased CFA by 50%. Other nanomaterials had no statistically significant antibacterial effect. Factors influencing ND and GO antibacterial activity against the E. coli and possibly against other bacteria are discussed.

Nanodiamond

Nanomaterials

Suspension

10.1002/pssb.201600237

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Citations (21)

パルスレーザ蒸着により成長させた極薄MoS_2膜の構造特性に及ぼすGaN/AlGaN/GaN(0001)及びSi(100)基板の影響【Powered by NICT】

Applied Surface Science (2017)

Š. Chromík Michaela Sojková Viliam Vretenár A. Rosová Edmund Dobročka

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Sensor for Monitoring the Moisture in Porous Materials

International Journal of Thermophysics (2013)

Danica Fidríková Viliam Vretenár Ivana Šimková Vladimír Greif Ján Vlčko

Ball (mathematics)

10.1007/s10765-013-1493-0

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Citations (8)

Covalent Diamond–Graphite Bonding: Mechanism of Catalytic Transformation

ACS Nano (2019)

Semir Tulić Thomas Waitz Mária Čaplovičová Gerlinde Habler M. Varga

Aberration-corrected transmission electron microscopy of the atomic structure of diamond–graphite interface after Ni-induced catalytic transformation reveals graphitic planes bound covalently to the diamond in the upright orientation. The covalent attachment, together with a significant volume expansion of graphite transformed from diamond, gives rise to uniaxial stress that is released through plastic deformation. We propose a comprehensive model explaining the Ni-mediated transformation of diamond to graphite and covalent bonding at the interface as well as the mechanism of relaxation of uniaxial stress. We also explain the mechanism of electrical transport through the graphitized surface of diamond. The result may thus provide a foundation for the catalytically driven formation of graphene–diamond nanodevices.

Synthetic diamond

10.1021/acsnano.9b00692

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Citations (52)

THERMOPHYSICAL SENSORS: THEORY AND APPLICATION OF THE HOT BALL

Viliam Vretenár

The paper deals with the theory and the application of the hot ball sensor. The sensor in a form of a small ball generates heat and simultaneously measures the temperature response. The thermal conductivity is to be determined from the measured signal. The sensor has been applied for monitoring of the moisture in the wall of the Cathedral Duomo in Florence and the setting of cement paste.

Ball (mathematics)

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Electrical Properties of Graphene Oxide Layers Prepared by Material Inkjet Printing

Key engineering materials (2016)

J. Pospı́šil Veronika Schmiedová Oldřich Zmeškal Viliam Vretenár Peter Kotrusz

The paper deals with the study of optical and electrical properties of inkjet-printed graphene oxide (GO) layers, which can be used e.g. for the preparation of various types of electronic devices. To ensure stable inkjet printing conditions of GO solution, mixture was thoroughly stirred for 1 h at room temperature or sonicated in the bath for 30 min. The thicknesses of prepared layers were determined by spectroscopic ellipsometry and profilometry. An electrical conductivity of GO was increased by the multistep reduction (due to annealing) – the conductivity was changed by these processes about seven orders of magnitude (GO is an isolator and reduced GO is a conductor). For electrical and dielectric measurements, samples with GO and mixture of GO with PEDOT were prepared. All current-voltage characteristics have a diode character. From AC measurements the bulk electrical conductivity and geometric capacity of prepared layers were determined.

10.4028/www.scientific.net/kem.674.109

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Citations (1)

Ohmic Contacts to P–GaN Based on the Single–Walled Carbon Nanotubes

Journal of Electrical Engineering (2013)

Jozef Liday Peter Vogrinčič Viliam Vretenár Mário Kotlár Marián Marton

Abstract We have designed and verified a new structure for ohmic contacts to p-GaN, mainly for applications in light emitting devices based on a layer of single-walled carbon nanotubes (SWCNT) and metallic layers of Cr and Au, namely in configuration Au/Cr/SWCNT/p-GaN. The layer of carbon nanotubes was deposited on p-GaN by spraying a solution of synthesized SWCNTs, while the layers of Cr and Au were vapour deposited. The effects of the annealing temperature and time upon the electrical properties of Au/Cr/SWCNT/p-GaN contacts have been studied. It has been found that the contact structure provides a low resistivity ohmic contact after subsequent annealing in N2 ambient at 700 °C for 1 minute.

Ohmic contact

Contact resistance

Electrical contacts

10.2478/jee-2013-0047

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Citations (2)

Model for Cuboid Shape Samples and its Analysis Used for Measurements of Thermophysical Properties of Sandstone

Measurement Science Review (2011)

Vlastimil Boháč Peter Dieška Viliam Vretenár Vladimír Greif

Cuboid

10.2478/v10048-011-0032-z

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Citations (16)