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Tytuł:
Influence of Annealing Temperature on $Y_2O_3:SiO_2$ Nanocomposite Prepared by Sol-Gel Process
Autorzy:
Ahlawat, R.
Aghamkar, P.
Powiązania:
https://bibliotekanauki.pl/articles/1205213.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Bc
61.46.Df
78.67.Bf
Opis:
Oxide nanoparticles embedded in a polymer matrix produce nanocomposites which are useful for optics and electronic applications. Yttrium oxide nanoparticles have received much attention due to their various properties and are significantly used in fundamental and application oriented fields. The present paper reports the influence of annealing temperature on the $Y_2O_3:SiO_2$ nanocomposite prepared by sol-gel process. $Y(NO_3)_3 ·4H_2O$ and tetraethoxysilane were used as precursors and obtained powdered form of $Y_2O_3:SiO_2$ composite. The powder sample was annealed at 500C and 900C for 6 h which were characterized by X-ray diffraction, Fourier transform infrared and transmission electron microscope. X-ray diffraction data described that the broadening of peaks decreases with increase in annealing temperature which may be due to the increase in particle size. Sample analyzed by Fourier transform infrared and transmission electron microscopy confirmed the grain size dependence on annealing temperature. Cubic phase of yttrium oxide crystal structure was obtained within the silica matrix. The nanocrystallites size has been calculated using Debye-Scherrer formula, Williamson-Hall plot and transmission electron micrographs and compared at two different temperatures (a) 500C and (b) 900C.
Źródło:
Acta Physica Polonica A; 2014, 126, 3; 736-739
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Separation and Electrical Properties of $WO_{3-x}$ Nanopowders via Partial Pressure High Energy Ball-Milling
Autorzy:
Al Mohammad, A.
Powiązania:
https://bibliotekanauki.pl/articles/1807792.pdf
Data publikacji:
2009-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
61.46.Df
64.60.Cn
Opis:
Reduction processes of $WO_{3}$ nanopowder either with carbon or with hydrogen were observed using X-ray powder diffraction and transmission electron microscope. The phase transformations, separation, grain size and electrical conductivity of $WO_{3-x}$ nanopowder during reductions via partial pressure high energy ball-milling have been studied. During the carbon-reduction process the monoclinic $WO_{3}$ structure transforms to nonstoichiometric Magneli phases $W_{40}O_{118}$, $WO_{2.9}$ and finally to $WO_{2}$ and W mixed phases. The Magneli $WO_{3-x}$ phases exhibit specific fringe contrast imaging of well-ordered crystallographic shear planes. In comparison, the monoclinic $WO_{3}$ structure transforms to hydrate $WO_{3}·1/3H_{2}O$, hexagonal $WO_{3}$, non-stoichiometric $WO_{2.7}$ and finally to $WO_{2}$ and W mixed phases during the hydrogen-reduction process. The inclusion of hydrogen atoms between the $WO_{6}$ octahedral structure shifts the reduction steps to lower milling times. It demonstrates that the formation of hydrate $WO_{3}$ phases enhances the amenability of the system to reduction. The activation energy for conduction was deduced from the Arrhenius equation and was found to depend on oxygen partial pressure or presence of the hydrogen atoms. The defect band model was used for interpretation of these behaviors. It supposes that the surface oxygen vacancies introduce donor levels in the gap of semiconductor, so free electrons are produced by reduction.
Źródło:
Acta Physica Polonica A; 2009, 116, 2; 240-244
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Annealed (0001) α-$Al_2O_3$ Surfaces on Heteroepitaxial Growth of Silver Nanoparticles
Autorzy:
Al-Mohammad, A.
Powiązania:
https://bibliotekanauki.pl/articles/1808108.pdf
Data publikacji:
2009-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.-a
81.15.Aa
61.05.jh
61.46.Df
Opis:
The effect of annealed (0001) α -$Al_2O_3$ surfaces on heteroepitaxial growth of silver nanoparticles were analysed by reflection high-energy electron diffraction, transmission electron microscope and selected area electron diffraction. Ag nanoparticles were deposited on 1× 1 stoichiometric and reconstructed (111)Al//(0001) α -$Al_2O_3$ with the Knudsen cell. The maximum cluster density method and the Lifethenz theory of Van der Waals energy were used to investigate the Ag//(0001)α -$Al_2O_3$ interface parameters. The growth modes, lattice parameters, nanoparticle forms and sizes are strongly dependent on the substrate surface structures. Initially, three-dimensional islands of Ag nanoparticles grow on both kinds of surfaces with partial hexagonal shapes. Ag nanoparticles on stoichiometric surface create the (111)Ag//(0001)α -$Al_2O_3$ interface without any preferred epitaxial direction. On this surface, Gaussian distribution is characteristic of an atom-by-atom growth mode with density of Ag nanoparticles lower than saturation density while a coalescence growth mode appears due to binary collisions between Ag nanoparticles accompanied by a liquid-like behaviour after saturation density. In case of reconstruction substrates, the epitaxial relationships between Ag nanoparticles and the surface are formed (111)Ag//(0001)α -$Al_2O_3$, 〈01\bar(1)〉Ag//[12\bar(3)0]α -$Al_2O_3$ or 〈01\bar(1)〉Ag//[1\bar(1)00]α-$Al_2O_3$. The Ag nanoparticles make rotation with angles between ± 6° around the epitaxial orientations 〈1\bar(1)00〉 or 〈12\bar(3)0〉. Only the atom-by-atom growth mode were found at all Ag nanoparticles growth processes.
Źródło:
Acta Physica Polonica A; 2009, 115, 3; 679-684
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of second harmonic generation in KDP/Al₂O₃ crystalline nanocomposite
Autorzy:
Andrushchak, N.
Kulyk, B.
Göring, P.
Andrushchak, A.
Sahraoui, B.
Powiązania:
https://bibliotekanauki.pl/articles/1052895.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
61.46.Df
68.37.Ps
42.65.Ky
Opis:
Crystalline nanocomposite KDP/Al₂O₃ was obtained by growth of KDP nanocrystals inside nanopores of amorphous alumina matrix (Al₂O₃) with pores diameter of 35 nm. Performed atomic force microscopy and X-ray diffraction analysis confirmed that Al₂O₃ matrix is filled up with a tetragonal phase KDP nanocrystals in preferred crystallographic orientation [100]. The nonlinear optical response was studied by means of second harmonic generation via the Maker fringe technique employing picosecond laser pulses at wavelength of 1064 nm. The polarization dependent second harmonic generation response was observed mainly due to the macroscopic crystalline structure anisotropy of KDP/Al₂O₃ nanocomposite. The investigation of such type of nanocomposites which combine nanoscale nonlinear optical materials has a great importance since they may improve the performance of entire system.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 856-859
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silver Nanoparticles as Enhancing Substrates for Raman and Fluorescence Spectroscopy
Autorzy:
Cyrankiewicz, M.
Wybranowski, T.
Kruszewski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1196708.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Fb
33.20.Kf
32.50.+d
61.46.Df
73.20.Mf
78.67.Bf
87.83.+a
Opis:
The enhancing properties of silver nanoparticles in surface-enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF) are studied in this work. The obtained results confirm that the partial aggregation of nanoparticles leads to a great increase of Raman scattering cross-section but there are significant differences in SERS-activity of colloidal silver treated with various aggregating compounds. The differences are interpreted through the analysis of both experimental and computational results. The same silver colloid covered with silica shell preventing the fluorescence quenching makes possible a several-fold increase in fluorescence emission. The effect strongly depends on thickness of the outer layer of nanoparticles. Geometrical parameters of nanoparticles (radius or radius and thickness of the adsorption layer in core-shell systems) are determined on the basis of the dynamic light scattering (DLS) data and extinction spectra analysis.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-11-A-15
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Temperature and Time on $Nd_2O_3-SiO_2$ Composite Prepared by the Solgel Process
Autorzy:
Duhan, S.
Aghamkar, P.
Powiązania:
https://bibliotekanauki.pl/articles/1812356.pdf
Data publikacji:
2008-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
61.46.Hk
78.67.Bf
Opis:
Using solgel method $Nd_2O_3-SiO_2$ binary oxide systems were prepared. The binary oxide transformed from the amorphous phase to nanocrystalline phase upon heat treatment in air. Characterization of the $Nd_2O_3-SiO_2$ was carried out by using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effect of the sintering temperature and time on the evolution of the binary oxide system was discussed. It is found that sintering time plays a pivotal role to obtain $Nd_2O_3-SiO_2$ nanocomposite. At temperature of 900°C, the sample was sintered for 12 h and monoclinic $Nd_2O_3$ nanocrystallites, with average crystallite size ≈12 nm, were obtained.
Źródło:
Acta Physica Polonica A; 2008, 113, 6; 1671-1677
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Surface Morphology of Nanocrystalline Silver Silicates
Autorzy:
Duhan, S.
Powiązania:
https://bibliotekanauki.pl/articles/1489860.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
61.46.Hk
78.67.Bf
Opis:
Microstructure and surface morphology of AgO nanocrystallites (25 nm) supported on $SiO_2$ and subjected to heat treatment in air up to 500C have been studied by transmission electron microscopy, scanning electron microscopy, and the Fourier transform infrared spectroscopy measurements. It has been found that heating at 500C resulted in spreading of AgO over silica and formation of quasi two-dimensional amorphous phase (silicate precursor) exhibiting very weak band at $566 cm^{-1}$ have appeared in the Fourier transform infrared spectroscopy. Nanocrystalline silver silicate of undefined structure formed at 300-500C.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 636-638
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:
Effects of pH Value on the Growth and Structural Properties of Sol-Gel Synthesized Nanostructured ZnO
Autorzy:
Gültekin, D.
Alaf, M.
Akbulut, H.
Powiązania:
https://bibliotekanauki.pl/articles/1399831.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
81.07.Wx
81.20.Fw
Opis:
The aim of the research presented is to investigate the effect of pH value on the structural and morphological properties of nanostructured ZnO products. Zinc acetate dihydrate $(Zn(CH_3COO)_2·2H_2O)$ has been used as precursor whereas distilled water is used as a solvent. The pH value of the sol was adjusted with monoethanolamine (MEA) and it changed from acid to base in nature. X-ray diffractometer has been used to determine preferred crystal orientation and particle size of the thin films. Film morphologies have been examined by using JEOL JSM 6060 LV scanning electron microscope equipped with energy-dispersive spectroscopy.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 330-332
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanostructured ZnO Photoelectrode Synthesis for Dye Sensitized Solar Cells
Autorzy:
Gültekin, D.
Alaf, M.
Akbulut, H.
Powiązania:
https://bibliotekanauki.pl/articles/1182877.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
61.46.Df
81.07.Wx
81.20.Fw
88.40.jm
Opis:
The main aims of this work were to produce and examine the characteristics of nanostructured ZnO in dye-sensitized solar cells. Parameters which are affected by the efficiency such as precursor materials, morphology were investigated. The Raman spectroscopy was used to investigate transformation from bulk material to solution. General morphologies and detailed structural characterizations were obtained using field emission scanning electron microscopy. X-ray diffractometer has been used to determine preferred crystal orientation and particle size of the ZnO nanostructures.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 301-303
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of ZnO Nanopowders and ZnO-CNT Nanocomposites Prepared by Chemical Precipitation Route
Autorzy:
Gültekin, D.
Alaf, M.
Akbulut, H.
Powiązania:
https://bibliotekanauki.pl/articles/1399778.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
81.07.Wx
81.05.Dz
61.48.De
81.20.Fw
Opis:
The aims of this work are synthesis of ZnO nanopowders and producing nanocomposites by mixing with carbon nanotubes. ZnO nanopowders have been synthesized by chemical precipitation route. Different amount of collected nanosized Zn-based precipitates and chemically oxidized carbon nanotubes powder have been mix together and annealed at 400°C. Characterization of produced nanopowders and nanocomposites have been carried out by X-ray diffractometer and scanning electron microscope.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 274-276
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Penetration of Gold Nanoparticles into Silicon Dioxide
Autorzy:
Ilkiv, I.
Kotlyar, K.
Amel'chuk, D.
Lebedev, S.
Cirlin, G.
Bouravleuv, A.
Powiązania:
https://bibliotekanauki.pl/articles/1033145.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Pq
61.46.Df
68.08.Bc
Opis:
We report on an experimental study of the thermal annealing processes under air and nitrogen atmospheres of colloidal Au nanoparticles deposited onto SiO₂/Si(100) samples. It was shown that Au nanoparticles during annealing under ambient conditions could penetrate inside silicon dioxide layers forming pores at that their lengths were found to be dependent on the annealing time. The influence of oxygen on the penetration process is discussed. At the same time, the annealing of Au nanoparticles under nitrogen conditions did not result in the formation of pores.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 366-369
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Mössbauer Study of Cerium-Based Reactive Sorbent
Autorzy:
Jiraskova, Y.
Bursik, J.
Zivotsky, O.
Lunacek, J.
Janos, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032876.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
75.60.Ej
76.80.+y
61.46.Df
75.30.Kz
75.50.Bb
Opis:
A new kind of magnetically separable composite consisting initially of magnetite and cerium carbonate nanograins was investigated using magnetic and Mössbauer methods at room and low temperatures. Various stages of calcination treatment in air resulted in a transformation of the cerium carbonate into cerium dioxide and magnetite into more complicated iron oxide compositions. The final CeO₂ nanograins on the surface of α-Fe₂O₃ were obtained after calcination at 973 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1096-1098
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Transition of Electrooxidized $Fe_3O_4$ to γ and $α-Fe_2O_3$ Nanoparticles Using Sintering Treatment
Autorzy:
Kazeminezhad, I.
Mosivand, S.
Powiązania:
https://bibliotekanauki.pl/articles/1365306.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.cd
61.46.Df
61.46.Bc
Opis:
In this work, electrosynthesis of $Fe_3O_4$ nanoparticles was carried out potentiostatically in an aqueous solution of $C_4H_{12}NCl$ which acts as supporting electrolyte and electrostatic stabilizer. $γ-Fe_2O_3$ nanoparticles were synthesized by controlling oxidation of the electrooxidized $Fe_3O_4$ nanoparticles at different temperature. Finally the phase transition to $α-Fe_2O_3$ nanoparticles was performed at high temperatures using sintering treatment. The synthesized particles were characterized using X-ray diffraction, Fourier transformation, infrared scanning electron microscopy with energy dispersive X-ray analysis, and vibrating sample magnetometry. Based on the X-ray diffraction results, the transition from $Fe_3O_4$ to cubic and tetragonal $γ-Fe_2O_3$ was performed at 200C and 650°C, respectively. Furthermore, phase transition from metastable $γ-Fe_2O_3$ to stable $α-Fe_2O_3$ with rhombohedral crystal structure was approved at 800°C. The existence of the stabilizer molecules at the surface of $Fe_3O_4$ nanoparticles was confirmed by Fourier transformation infrared spectroscopy. According to scanning electron microscopy images, the average particles size was observed around 50 nm for electrooxidized $Fe_3O_4$ and $γ-Fe_2O_3$ nanoparticles prepared at sintering temperature lower than 900°C, however by raising sintering temperature above 900C the mean particles size increases. Energy dispersive X-ray point analysis revealed that the nanoparticles are almost pure and composed of Fe and O elements. According to the vibrating sample magnetometry results, saturation magnetization, coercivity field, and remnant magnetization decrease by phase transition from $Fe_3O_4$ to $Fe_2O_3$.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1210-1214
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Wyświetlanie 1-15 z 30

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