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Instrumentation for study of nanomaterials in NPI REZ (New laboratory for material study in Nuclear Physics Institute in REZ)
Bejšovec, Václav ; Cannavó, Antonino ; Ceccio, Giovanni ; Hnatowicz, Vladimír ; Horák, Pavel ; Lavrentiev, Vasyl ; Macková, Anna ; Tomandl, Ivo ; Torrisi, Alfio ; Vacík, Jiří
Nano-sized materials become irreplaceable component of a number of devices for every aspect of human life. The development of new materials and deepening of the current knowledge require a set of specialized techniques-deposition methods for preparation/modification of the materials and analytical tools for proper understanding of their properties. A thoroughly equipped research centers become the requirement for the advance and development not only in nano-sized field. The Center of Accelerators and Nuclear Analytical Methods (CANAM) in the Nuclear Physics Institute (NPI) comprises a unique set of techniques for the synthesis or modification of nanostructured materials and systems, and their characterization using ion beam, neutron beam and microscopy imaging techniques. The methods are used for investigation of a broad range of nano-sized materials and structures based on metal oxides, nitrides, carbides, carbon-based materials (polymers, fullerenes, graphenes, etc.) and nano-laminate composites (MAX phases). These materials can be prepared at NPI using ion beam sputtering, physical vapor deposition and molecular beam epitaxy. Based on the deposition method and parameters, the samples can be tuned to possess specific properties, e.g., composition, thickness (nm-μm), surface roughness, optical and electrical properties, etc. Various nuclear analytical methods are applied for the sample characterization. RBS, RBS-channeling, PIXE, PIGE, micro-beam analyses and Transmission Spectroscopy are accomplished at the Tandetron 4130MC accelerator, and additionally the Neutron Depth Profiling (NDP) and Prompt Gamma Neutron Activation (PGNA) analyses are performed at an external neutron beam from the LVR-15 research reactor. The multimode AFM facility provides further surface related information, magnetic/electrical properties with nano-metric precision, nano-indentation, etc.
Study of lithium encapsulation in porous membrane using ion and neutron beams
Ceccio, Giovanni ; Cannavó, Antonino ; Horák, Pavel ; Torrisi, Alfio ; Tomandl, Ivo ; Hnatowicz, Vladimír ; Vacík, Jiří
Ion track-etched membranes are porous systems obtained by etching of the latent ion tracks using a suitable etchant solution. In this work, control of the pores' spatial profiles and dimensions in PET polymers was achieved by varying etching temperature and etching time. For determination of the pores' shape, Ion Transmission Spectroscopy technique was employed. In this method, alterations of the energy loss spectra of the transmitted ions reflect alterations in the material density of the porous foils, as well as alterations of their thickness. Simulation code, developed by the team, allowed the tomographic study of the ion track 3D geometry and its evolution during chemical etching. From the doping of porous membranes with lithium-based solution and its analysis by Thermal Neutron Depth Profiling method, the ability of porous PET membranes to encapsulate nano-sized material was also inspected. The study is important for various applications, e.g., for catalysis, active agents, biosensors, etc.
Production and characterization of micro-size pores for ion track etching applications
Cannavó, Antonino ; Havránek, Vladimír ; Lavrentiev, Vasyl ; Torrisi, L. ; Cutroneo, Mariapompea ; Ceccio, Giovanni ; Torrisi, Alfio ; Horák, Pavel ; Vacík, Jiří
For many years the applications of ion track etch materials have increased considerably, like charged particles detection, molecular identification with nanopores, ion track filters, magnetic studies with nanowires and so on. Over the materials generally used as track detector, the Poly-Allyl-Diglycol Carbonate (PADC), offers many advantages, like its nearly 100 % detection efficiency for charged particle, a high resistance to harsh environment, the lowest detection threshold, a high abrasion resistance and a low production costs. All of these properties have made it particularly attractive material, even if due to its brittleness, obtaining a thin film (less than 500 μm) is still a challenge. In this work, PADC foils have been exposed to a-particles emitted by a thin radioactive source of 241Am and to C ions from the Tandetron 4130 MC accelerator. The latent tracks generated in the polymer have been developed using a standard etching procedure in 6.25 NaOH solution. The dependence of the ion tracks' geometry on the ion beam energy and fluence has been evaluated combining the information obtained through a semiautomatic computer script that selects the etched ion tracks according to their diameter and mean grey value and nanometric resolution images by atomic force microscopy.
Laser-generated nanoparticles to change physical properties of solids, liquids and gases
Torrisi, Alfio ; Cutroneo, Mariapompea ; Ceccio, Giovanni ; Cannavó, Antonino ; Horák, Pavel ; Torrisi, L. ; Vacík, Jiří
Synthesis of nanoparticles was possible employing a Nd: YAG pulsed laser at fundamental harmonic. The production of nanoparticles in water depends mainly on the laser parameters (pulse duration, energy, wavelength), the irradiation conditions (focal spot, repetition rate, irradiation time) and the medium where the ablation occurs (solid target, water, solution concentration). The nanoparticles can be introduced in solids, liquids or gases to change many physical characteristics. The optical properties of polymers and solutions, the wetting ability of liquids, the electron density of laser-generated plasma, represent some examples that can be controlled by the concentration of metallic nanoparticles (Au, Ag, Ti, Cu). Some bio-medical applications will be presented and discussed.
Morphological characterization of monolithic columns
Širc, Jakub ; Bosáková, Zuzana (advisor) ; Feltl, Ladislav (referee) ; Vacík, Jiří (referee)
I ntroduction Iligh-perfbnnance liquid chromatography (lIPLC) is currently one of the ntost common anal1'tica| soparation 1cclrtlic1ttcs' Duc to its ability to separate a widc range oÍ'a structurally rlil.Íěrent lorr- and high ntolecular oompourtds o1'polar as rvcll as non-polar nature, tIPLC found application in analylical laboratories in thc field ofrnedicine. plrarrrracy. biology. industry and the environmelt. Although the oonverttional packed colunrns are used in most of ths chronratographic applications, stationary phases in the Íbrnr of.particles have their limitations and disadvňtages. Quality o| the packed colutltns is irrÍluerrced by a rrunrber ol. paranreters' |or exanrple relatiňly conrplicated process ol.lilling I l |' Variances in the particle size and inegularities in their shape have á n!'galive inrpact on thc chrotratoBraphic process. Conrmon problems of the packed oolunrns are an inhomogeucous distribution ol the particles ol'various sizes and their settling in the column u,ith consequent greation of dcad voIuntes' FIighly uniÍbm spherical partic|es prcpared by suspension polynrerization can partlY solve stlnte Iintitations. hor,vever. disadvantagcs arising Íionr the prin|iple of tlrc packcd coluurns still rcntain. Prornising altcmative to thc paoked colunrns are monoliths. made of a block...
Lavrentiev, Vasyl ; Lavrentieva, Inna ; Vacík, Jiří
The morphology and roughness of the films show great change around some critical composition x(c) of the mixture film (x(c) approximate to 3). The films with lower Co content (x < 3) is rather smooth and the roughness is rather low. However, if x >= 3, the roughness of the CoxC60 films dramatically increases and sharp protrusions appear on the surface that reflects an important phase transformation in the film structure. The obtained AFM results define the concentration interval of the Co solubility in solid C-60 (x < 3), which was found to be narrower than that evaluated from spectroscopic experiments (see the text). This interval suggests a formation of the Co1C60 and Co2C60 fullerides in the CoxC60 mixtures where the Co atoms occupy the tetrahedral holes in the fullerene lattice. The dramatic change of the surface morphology at x >= 3 reflects the pronounced Co clustering which likely occurs due to numerical filling the octahedral pores. Formation of the protrusions on the surface of the supersaturated CoxC60 mixture films (x > 3) is a consequence of the compressive stress arising in the film due to the Co clustering.
Horák, Pavel ; Khun, J. ; Vrňata, M. ; Bejšovec, Václav ; Lavrentiev, Vasyl ; Vacík, Jiří
Thin layers (90 nm) of nickel(II)- and copper(II)- oxide were deposited onto ceramic sensor substrates equipped with interdigital electrodes for signal reading. The deposition was carried out in two or three steps: (i) sputtering by means of Ar ion beam from pure (99.99%) metal targets, (ii) following thermal oxidation (400 degrees C for 5 h) in air, (iii) in some cases - sputtering of Pd catalyst to the surface. Then the impedance response of produced sensors (NiO, NiO+Pd, CuO, CuO+Pd) to 1000 ppm of hydrogen and 1000 ppm of methanol vapor was measured. Impedance measurements were performed in the frequency range from 40 Hz to 100 MHz. The obtained data were depicted in Nyquist representation (i.e. imaginary vs. real part of complex impedance). These diagrams have a character of one complete and one incomplete semicircle, each of them corresponding to a parallel RC-element. It was proved, that both NiO and CuO behave like p-type semiconductors; the sensor impedance increases on exposure to reducing gases. The best sensitivity was achieved on NiO+Pd sensor - during detection of hydrogen (1000 ppm) the real part of complex impedance measured at 40 Hz increased from 120 to 350 Omega.

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3 Vacík, Jakub
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