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Wyświetlanie 1-7 z 7
Tytuł:
Percolation Phenomena in $Cu_{x}(SiO_{y})_{100-x}$ Nanocomposite Films Produced by Ion Beam-Sputtering
Autorzy:
Koltunowicz, T.
Zukowski, P.
Czarnacka, K.
Svito, I.
Fedotov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402230.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.37.+q
72.80.Ga
73.22.-f
61.46.Df
64.60.ah
Opis:
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.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 908-911
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hopping Conductance in Nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1 - x}$ Manufactured by Ion-Beam Sputtering of Complex Target in $Ar+O_2$ Ambient Gas
Autorzy:
Kołtunowicz, T.
Zhukowski, P.
Fedotova, V.
Saad, A.
Fedotov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1503812.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
73.22.-f
84.37.+q
72.20.Ee
Opis:
We report the investigation of a real part of the admittance σ of granular nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1 - x}$ with 0.30 < x < 0.70 in the dielectric (hopping) regime. An analysis of the σ(T, f, x) dependences in the as-deposited and annealed films over the temperature 77 K < T < 300 K and frequency 50 < f < $10^6$ Hz ranges displayed the predominance of an activation (hopping) conductance mechanism with dσ/ dT > 0 for the samples below the percolation threshold $x_{C}$ ≈ 0.76 ± 0.05. Based on the earlier models for hopping AC conductance, computer simulation of the frequency coefficient $α_{f}$ of hopping conductance depending on the probability of jump p, frequency f, and also on the shape of σ(f) curve was performed. The experimental and simulation results revealed a good agreement.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 39-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Features of Real Part of Admittance in the Nanocomposites $(Fe_{45}Co_{45}Zr_{10})_{x}(Al_2O_3)_{100 - x}$ Manufactured by the Ion-Beam Sputtering Technique with Ar Ions
Autorzy:
Kołtunowicz, T.
Zhukowski, P.
Fedotova, V.
Saad, A.
Larkin, A.
Fedotov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1503798.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
73.22.-f
84.37.+q
72.20.Ee
Opis:
The temperature and frequency dependences of the admittance real part σ (T, f) in granular $(Fe_{45}Co_{45}Zr_{10})_{x}(Al_2O_3)_{100 - x}$ nanocomposite films around the percolation threshold $x_{C}$ were investigated. The behaviour of σ (T, f) vs. the temperature and frequency over the ranges 77-300 K and 50 Hz-1 MHz, respectively, displays the predominance of an activation (hopping) conductance mechanism for the samples below the percolation threshold $x_{C}$ and of a metallic one beyond the $x_{C}$ determined as 54 ± 2 at.%. The mean hopping range d for the nanoparticles diameter D was estimated at different metallic phase content x.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 35-38
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Formation of Noncoil-Like Inductance in Nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1-x}$ Manufactured by Ion-Beam Sputtering of Complex Targets in $Ar+O_2$ Atmosphere
Autorzy:
Zhukowski, P.
Kołtunowicz, T.
Węgierek, P.
Fedotova, J.
Fedotov, A.
Larkin, A.
Powiązania:
https://bibliotekanauki.pl/articles/1503848.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
73.22.-f
81.40.Ef
84.37.+q
72.20.Ee
Opis:
This paper investigates the inductive contribution to AC conductance in the granular nanocomposites $(Fe_{0.45}Co_{0.45}Zr_{0.10})_{x}(Al_2O_3)_{1-x}$. The initial nanocomposites studied were manufactured in $Ar+O_2$ atmosphere by ion-beam sputtering of the target containing $Fe_{0.45}Co_{0.45}Zr_{0.10}$ and alumina stripes and then subjected to the annealing procedure in air over the temperature range 373 K < $T_{a}$ < 873 K. These samples, before and after annealing, were studied using the temperature 77 K < $T_{p}$ < 300 K and frequency 50 Hz < f < 1 MHz dependences of a real part of the admittance σ(T, f). Analysis of the observed σ (f, $T_{p}$) dependences for x < 0.5 demonstrated that in the studied samples the equivalent circuits with the capacitive and noncoil-like inductive contributions can be accomplished. Just in this case, the capacitive properties of RLC circuit with the phase angle - 90° ≤ $\Theta_{L}$ < 0° are exhibited at low frequencies and the inductive properties with 0° ≤ $\Theta_{H}$ < 90° become apparent at high frequencies. A value of the critical frequency $f_{R}$, where $\Theta_{H}$ changes sign, depends on the metallic phase concentration x, measuring temperature $T_{p}$, and annealing temperature $T_{a}$.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 43-45
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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
Autorzy:
Svito, I.
Fedotov, A.
Saad, A.
Koltunowicz, T.
Zukowski, P.
Bury, P.
Powiązania:
https://bibliotekanauki.pl/articles/1366313.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
72.20.Ee
64.60.ah
Opis:
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.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1351-1354
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanisms of Carrier Transport in $Cu_x(SiO_2)_{1-x}$ Nanocomposites Manufactured by Ion-Beam Sputtering with Ar Ions
Autorzy:
Fedotov, A.
Mazanik, A.
Svito, I.
Saad, A.
Fedotova, V.
Czarnacka, K.
Koltunowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1402220.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.37.+q
72.80.Ga
73.22.-f
61.46.Df
64.60.ah
Opis:
The present paper investigates the temperature/frequency dependences of admittance Z in the granular $Cu_x(SiO_2)_{1-x}$ 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.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 883-886
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance in n-Si/$SiO_2$/Ni Nanostructures Manufactured by Swift Heavy Ion-Induced Modification Technology
Autorzy:
Fedotova, J.
Ivanou, D.
Ivanova, Y.
Fedotov, A.
Mazanik, A.
Svito, I.
Streltsov, E.
Saad, A.
Tyutyunnikov, S.
Kołtunowicz, T.
Demyanov, S.
Fedotova, V.
Powiązania:
https://bibliotekanauki.pl/articles/1504014.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
81.05.Rm
73.22.-f
73.50.Jt
Opis:
A study of magnetotransport in the n-Si/$SiO_2$/Ni nanostructures with granular Ni nanorods in $SiO_2$ pores was performed over the temperature range 2-300 K and at the magnetic fields induction up to 8 T. The n-Si/$SiO_2$/Ni Schottky nanostructures display the enhanced magnetoresistive effect at 25 K due to the impurity avalanche mechanism.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 133-135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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