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Wyszukujesz frazę "Saad, A." wg kryterium: Autor


Wyświetlanie 1-10 z 10
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:
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:
Admittance and Permittivity in Doped Layered $TlGaSe_2$ Single Crystals
Autorzy:
Dawood, S.
Fedotov, A.
Mammadov, T.
Zukowski, P.
Koltunowicz, T.
Saad, A.
Drozdov, N.
Powiązania:
https://bibliotekanauki.pl/articles/1365735.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
84.37.+q
64.70.Nd
Opis:
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 $N_\text{imp}$ < 0.5 at.% nonequilibrium electronic phase transition is observed. Doping with $N_\text{imp}$ > 0.5 at.% resulted in full suppression of this phase transition presence.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1267-1270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Voltage and Current Resonance in Nanocomposite $(FeCoZr)_x(CaF_2)_{100-x}$ Produced by Ion-Beam Sputtering in Pure Argon Atmosphere
Autorzy:
Koltunowicz, T.
Zukowski, P.
Bondariev, V.
Fedotov, A.
Svito, I.
Fedotova, J.
Saad, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402224.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Pq
79.20.Rf
81.40.Ef
72.80.Le
Opis:
In this paper the results of investigations of electrical properties of metal-dielectric nanocomposites $(FeCoZr)_x(CaF_2)_{100-x}$ 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.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 897-900
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of the risk for human health of Enterovirus and Hepatitis A virus in clinical and water sources from three metropolitan cities of Pakistan
Autorzy:
Ahmad, T.
Adnan, F.
Nadeem, M.
Kakar, S.J.
Anjum, S.
Saad, A.
Waheed, A.
Arshad, N.
Powiązania:
https://bibliotekanauki.pl/articles/2081926.pdf
Data publikacji:
2018
Wydawca:
Instytut Medycyny Wsi
Tematy:
epidemiology
Enterovirus (EntV)
HAV
PCR
virology
Opis:
Introduction. Molecular studies have confirmed the silent circulation of enterovirus (EntV) and hepatitis A virus in the environment, even in the absence of clinical manifestation. Viral pathogens are among the major causes of disease outbreaks, particularly in the bigger cities and both in the developed and underdeveloped nations. Materials and method. Between June 2016 – June 2017, 97 samples of drinking water, river water polluted with sewage and blood were selected and obtained from high risk communities in Pakistan. Negatively charged membrane filters were used to concentrate the virus, followed by the use of specific PCR primers set for quick identification of the waterborne viruses. Results. Enteroviruses were recovered from 40%, 28.57% and 33.33% of river water polluted with sewage samples in Lahore, Islamabad and Rawalpindi, respectively, while the presence of 13.13% and 11.76% of viral load was also confirmed in the drinking water of Lahore and Rawalpindi, respectively. A high prevalence of HAV (12.5% and 21.05%) was also verified in the clinical samples. Phylogenetic analysis indicated close resemblance of HAV isolates with the Indian strains. This study is the first ever comparative analysis of the EntV and HAV isolated from environmental samples and clinical specimen on a molecular level. Conclusions. The parallel surveillance of EntV and HAV in the river water polluted with sewage, and clinical samples is quite helpful for controlling and reducing the disease burden of the waterborne illnesses.
Źródło:
Annals of Agricultural and Environmental Medicine; 2018, 25, 4; 708-713
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric Properties of $Ca_3Co_4O_9$-Based Ceramics Doped with Fe and/or Y
Autorzy:
Fedotov, A.
Mazanik, A.
Svito, I.
Saad, A.
Troyanchuk, I.
Bushinski, M.
Fedotova, V.
Zukowski, P.
Koltunowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1366301.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
46.25.Hf
62.20.D-
82.45.Xy
Opis:
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.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1344-1347
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropic Magnetoresistance of Ni Nanorod Arrays in Porous SiO₂/Si Templates Manufactured by Swift Heavy Ion-Induced Modification
Autorzy:
Fedotova, J.
Ivanou, D.
Mazanik, A.
Svito, I.
Streltsov, E.
Saad, A.
Zukowski, P.
Fedotov, A.
Bury, P.
Apel, P.
Powiązania:
https://bibliotekanauki.pl/articles/1402223.pdf
Data publikacji:
2015-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Km
81.15.Jj
75.47.De
Opis:
In this work anisotropic magnetoresistance in nanogranular Ni films and Ni nanorods on Si(100) wafer substrates was studied in wide ranges of temperature and magnetic field. To produce Ni films and nanorods we used electrochemical deposition of Ni clusters either directly on the Si substrate or into pores in SiO₂ layer on the Si substrate. To produce mesopores in SiO₂ layer, SiO₂/Si template was irradiated by a scanned beam of swift heavy 350 MeV ¹⁹⁷Au²⁶⁺ ions with a fluence of 5×10⁸ cm¯² and then chemically etched in diluted hydrofluoric acid. Pores, randomly distributed in the template have diameters of 100-250 nm and heights about 400-500 nm. Comparison of temperature dependences of resistance and magnetoresistance in Ni films and n-Si/SiO₂/Ni structures with Ni nanorods showed that they are strongly dependent on orientation of magnetic field and current vectors relative to each other and the plane of Si substrate. Moreover, magnetoresistance values in n-Si/SiO₂/Ni nanostructures can be controlled not only by electric field applied along Si substrate but also by additionally applied transversal bias voltage.
Źródło:
Acta Physica Polonica A; 2015, 128, 5; 894-896
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 1-10 z 10

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