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1
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Dielectric Properties of (CoFeZr)_x(PZT)_{100-x} Nanocomposites Produced with a Beam of Argon and Oxygen Ions

100%
Koltunowicz T.
Acta Physica Polonica A
|
2014
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vol. 125
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issue 6
1412-1415
EN
In this paper it was established that nanocomposite (FeCoZr)_x(PZT)_{100-x}, with x=90.0 at.%, produced by ion sputtering with argon and oxygen beam remains under the percolation threshold. It is related to the compound structure of films and creation of coat consisting of metallic oxides on surface of metallic phase nanogranules, which prevents electric contact between nanoparticles. Verification of the Arrhenius dependences for capacity and conductivity demonstrates that dominant part of metallic phase nanogranules has metal oxide coatings. Only a small number of nanogranules (probably around a few percent) does not have oxide coating.
2
Content available remote

XRD Analysis of Synthetic Diamond Powders Irradiated with Electrons

51%
Shishonok E., Luhin V., Koltunowicz T.
Acta Physica Polonica A
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2015
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vol. 128
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issue 5
912-914
EN
Powders of synthetic diamond with low strength were sorted on sets with a different grain size. The synthetic diamond sets had various crushing strengths and morphology. They were irradiated with high energy electrons (6.5 MeV, D=2×10¹⁹ cm¯²) and analyzed using X-ray diffraction (Cu K_α) before and after irradiation. As established from nonlinearity of the a(Θ)=f{R(Θ)} dependences and observed extra splittings in X-ray diffraction patterns (in addition to α₁-α₂ doublets), crystal lattice of synthetic diamond from different sets was variously distorted. Irradiation led to decreasing distortions more significantly, the higher the initial strength of the set was. The made conclusions coincide well with our previous results on synthetic diamond powders which were irradiated under various softer conditions with direct measurements of synthetic diamond crushing strength without X-ray diffraction analysis. X-ray diffraction allows to presort synthetic diamond of critically low relative mechanical strength as well as evaluate resistance of diamond crystal lattice against heavy irradiation and other external impacts.
3
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Composition of Surface Layers Prepared by Ion Beam Assisted Deposition of Catalytic Metals from Pulsed Arc-Discharge Plasma onto Carbon Paper Substrates

51%
Poplavsky V., Luhin V., Koltunowicz T.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
295-298
EN
The layers were prepared by ion beam assisted deposition of iridium and platinum onto AVCarb® Carbon Fiber Paper P50 electrocatalyst supports for the production of diffusion layers of the membrane-electrode assemblies of low temperature fuel cells with polymer electrolyte membrane. Formation of the layers in the ion beam assisted deposition mode, by means of the deposition of metal and mixing of precipitating layer with the substrate by the accelerated (U=10 kV) ions of the same metal, was performed. In this process neutral fraction of metal vapour and ionized plasma of vacuum pulsed electric arc discharge were used. The investigations of morphology and composition of layers were carried out by the scanning electron microscopy, energy dispersive X-ray microanalysis, wave dispersive X-ray fluorescence analysis, and the Rutherford backscattering spectrometry methods. It was established that the obtained catalytic layers contain atoms of the deposited metals and substrate material as well as impurity oxygen atoms. The surfaces contain also metal inclusions of several micrometer size which arise from the precipitation of deposited metal droplets from the arc discharge of an ion source. The content of iridium and platinum atoms in the layers is ≈2×10¹⁶ cm¯²; the concentration of the deposited metals equals about several atomic percent.
4
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The Kinetics of the Change of SnO_{x} Thin Films Conductivity during the Gas-Adsorptive Interaction

51%
Zarapin V., Luhin V., Zukowski P., Koltunowicz T.
Acta Physica Polonica A
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2014
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vol. 125
|
issue 6
1319-1323
EN
The subjects of investigation are thin semiconductor SnO_{x} films received by thermal oxidation. The influence of gas environments on electrical conductivity of films were investigated by a static way by measurement of kinetic and equilibrium isotherm of adsorption of trimethylamine, alcohol, hydrogen sulfide and ammonia. The communication between a type isotherm of adsorption, chemical nature of gas and temperature is shown.
5
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Percolation Phenomena in Cu_{x}(SiO_{y})_{100-x} Nanocomposite Films Produced by Ion Beam-Sputtering

45%
Koltunowicz T., Zukowski P., Czarnacka K., Svito I., Fedotov A.
Acta Physica Polonica A
|
2015
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vol. 128
|
issue 5
908-911
EN
In this paper the results of examinations of nanocomposites Cu_{x}(SiO_{y})_{100-x} produced by ion beam sputtering using argon ions were presented. The examinations were performed by the use of ac devices for measuring frequency in the range 50 Hz-1 MHz and temperatures from 81 K to 273 K. The measurements were performed for the samples directly after production. Based on temperature dependences of conductivity σ , which were determined at the frequency 100 Hz, the Arrhenius graphs were prepared. From these graphs conductivity activation energies ΔE were calculated. Dependences of conductivity and activation energy of electrons on the metallic phase content x at the frequency 100 Hz were determined. Analysis of the obtained dependences shows that conductivity is a parabolic function of the metallic phase content x in nanocomposites. Changes of activation energies of nanocomposites, in which metallic phase contents are in the ranges x < 12 at.% and x > 68 at.%, demonstrate negative values - metallic type of conductivity. In the range 12 at.% < x < 68 at.% activation energies have positive values - the dielectric type of conductivity. It was established that for the metallic phase content of about 68 at.% the real percolation threshold occurs, and the conduction changes from dielectric to metallic type.
6
Content available remote

Application of HPLC for the Analysis of Secoisolariciresinol Diglucoside in Flaxseeds

45%
Feskova A., Luhin V., Leontiev V., Sovastei O., Koltunowicz T.
Acta Physica Polonica A
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2013
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vol. 123
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issue 5
834-836
EN
High-pressure liquid chromatography - electrospray ionization-mass spectrometry coupled with the PDA detector was used for the analysis of secoisolariciresinol diglucoside in flaxseeds. The research was carried out using the spectrometer "Waters" on the BDS HYPERSIL column C_{18} 250 × 4.6 mm, with the diode-array PDA 996 and the mass-detectors Micromass ZQ 2000 with the electrospray ionization. As a mobile phase acetonitrile and water with 0.1% formic acid were used. The content of secoisolariciresinol diglucoside in the flaxseeds of 12 cultivar was determined.
7
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Voltage and Current Resonance in Nanocomposite (FeCoZr)_x(CaF₂)_{100-x} Produced by Ion-Beam Sputtering in Pure Argon Atmosphere

39%
Koltunowicz T., Zukowski P., Bondariev V., Fedotov A., Svito I., Fedotova J., Saad A.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 5
897-900
EN
In this paper the results of investigations of electrical properties of metal-dielectric nanocomposites (FeCoZr)_x(CaF₂)_{100-x} are presented. The samples with the metallic phase content x=45.7 at.% were produced by ion-beam sputtering method in pure argon atmosphere, and subsequently annealed at 398 K for 15 min. The measurements of electrical properties were performed in the frequency range from 50 Hz to 1 MHz. The frequency dependences of phase angle θ, capacity C_{p}, conductivity σ and dielectric loss factor tanδ were measured at seven different temperatures ranging from 148 K to 263 K. It was found that the nanocomposite exhibits the phenomena of voltage resonance and current resonance, characteristic of the conventional RLC circuits with series and parallel connections of elements.
8
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Low-Temperature DC Carrier Transport in (Co_{0.45}Fe_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1-x} Nanocomposites Sputtered in Mixed Argon-Oxygen Atmosphere

39%
Svito I., Fedotov A., Saad A., Koltunowicz T., Zukowski P., Bury P.
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EN
This paper studies the temperature dependences (2 < T < 300 K) of the DC conductivity σ(T) for the (Co_{0.45}Fe_{0.45}Zr_{0.10})_x(Al_2O_3)_{1-x} nanocomposites (30 < x < 65 at.%) sputtered in Ar + O_2 atmosphere. It is shown that at temperatures lower than 100-150 K dependences of DC conductance on temperature for all the studied samples are due to the Shklovski-Efros variable range hopping mechanism. It was also observed that σ(x,T) dependences can be attributed to the formation of FeCo-based oxide "shells" around metallic alloy nanoparticles due to incorporation of oxygen in the vacuum chamber during the deposition procedure.
9
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Mechanisms of Carrier Transport in Cu_x(SiO₂)_{1-x} Nanocomposites Manufactured by Ion-Beam Sputtering with Ar Ions

39%
Fedotov A., Mazanik A., Svito I., Saad A., Fedotova V., Czarnacka K., Koltunowicz T.
Acta Physica Polonica A
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2015
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vol. 128
|
issue 5
883-886
EN
The present paper investigates the temperature/frequency dependences of admittance Z in the granular Cu_x(SiO₂)_{1-x} nanocomposite films around the percolation threshold x_{C} in the temperature range of 4-300 K and frequencies of 20-10⁶ Hz. The behavior of low-frequency ReZ(T) dependences displayed the predominance of electrons hopping between the closest Cu-based nanoparticles for the samples below the percolation threshold x_{C} ≈ 0.59 and nearly metallic behaviour beyond the x_{C}. The high-frequency curves ReZ(f) at temperatures T > 10 K for the samples with x < x_{C} exhibited behavior close to ReZ(f) ≈ f^{-s} with s ≈ 1.0 which is very similar to the known Mott law for electron hopping mechanism. For the samples beyond the percolation threshold (x > x_{C}), the frequency dependences of ReZ(f) displayed inductive-like (not capacitive) behaviour with positive values of the phase shift angles.
10
Content available remote

Electrochemically Deposited Cobalt Nanoarrays in SiO_2/n-Si Templates Produced by Swift Heavy Ion-Induced Modification Technology

39%
Koltunowicz T., Zhukowski P., Fedotova J., Bayev V., Streltsov E., Baran L.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 5
929-931
EN
Nanoarrays of Co nanorods were formed by means of electrochemical deposition in the nanoporous SiO_2/n-Si templates. Structure and magnetic properties at room temperatures were studied by means of atomic force and scanning electron microscopies, vibrating sample magnetometry. The presence of perpendicular magnetic anisotropy component at room temperature makes Co nanorods in the nanoporous SiO_2/n-Si templates promising for nanoelectronic devices and biomedical applications.
11
Content available remote

Admittance and Permittivity in Doped Layered TlGaSe_2 Single Crystals

39%
Dawood S., Fedotov A., Mammadov T., Zukowski P., Koltunowicz T., Saad A., Drozdov N.
Acta Physica Polonica A
|
2014
|
vol. 125
|
issue 6
1267-1271
EN
In doped TlGaSe_2 crystals the phase transitions at low temperatures (100-170 K) were observed using admittance and dielectric spectroscopy in a temperature range of 80-320 K. The admittance and permittivity measurements in the studied samples indicated that after Fe or Tb doping by impurities with concentrations N_{imp} < 0.5 at.% nonequilibrium electronic phase transition is observed. Doping with N_{imp} > 0.5 at.% resulted in full suppression of this phase transition presence.
12
Content available remote

Thermoelectric Properties of Ca_3Co_4O_9-Based Ceramics Doped with Fe and/or Y

33%
Fedotov A., Fedotov A., Mazanik A., Svito I., Saad A., Troyanchuk I., Bushinski M., Fedotova V., Zukowski P., Koltunowicz T.
Acta Physica Polonica A
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2014
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vol. 125
|
issue 6
1344-1347
EN
We describe here structure and temperature dependences of conductivity σ(T), the Seebeck coefficient α(T), thermal conductivity λ(T) and figure-of-merit ZT(T) in Ca_3Co_4O_9 ceramics, doped with Fe and Y, depending on compacting pressure (0.2 or 6 MPa) and temperature (300 < T < 700 K). It is shown that introduction of iron and yttrium to ceramics does not alter the crystalline structure of the material. Increasing the pressure in the compacting process before the additional diffusion annealing leads to a smaller-grained structure and increase σ and λ due to reducing of the synthesized samples porosity. The Seebeck coefficients of nanocomposite ceramics Ca_3Co_{3.9}Fe_{0.1}O_9 and (Ca_{2.9}Y_{0.1})(Co_{3.9}Fe_{0.1})O_9 have linear dependences on temperature is not changed after increase of compacting pressure. Electrical-to-heat conductivity ratio (σ/λ) for the samples compacted at high (6 GPa) pressure increases not more than 20-30% in comparison with ones compacted at low (0.2 GPa) pressure, whereby ZT is increased more than 50%. The main reason for this effect is samples porosity reduction with the compacting pressure increase.
13
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Ion-Induced Modification of Structure and Magnetic Anisotropy in Granular FeCoZr-CaF₂ Nanocomposite Films

33%
Kasiuk J., Fedotova J., Przewoznik J., Kapusta C., Skuratov V., Milosavljevic M., Bondariev V., Koltunowicz T.
Acta Physica Polonica A
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2015
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vol. 128
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issue 5
828-831
EN
The paper reports on the results of structural analysis and magnetometry of granular nanocomposite films FeCoZr-CaF₂ irradiated with Xe and Kr ions at different fluences. The observed effect of enhanced perpendicular magnetic anisotropy characterizing pristine films is discussed with respect to the irradiation regimes and structural changes of the films originating from the impact of ions.
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