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    Wyświetlanie 1-26 z 26
    Tytuł:
    Functionalization and characterization of MWCNT produced by different methods
    Autorzy:
    Tomova, A.
    Gentile, G.
    Grozdanov, A.
    Errico, M.
    Paunović, P.
    Avella, M.
    Dimitrov, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1070616.pdf
    Data publikacji:
    2016-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.De
    Opis:
    The subject of this study is chemical functionalization as means of structural modification of multiwalled carbon nanotubes. The main goal of the experiments was to create highest density of carboxyl groups on multiwalled carbon nanotubes surface, necessary for further nanocomposite application. Two different types of multiwalled carbon nanotubes (I: outer diameter d=50÷ 100 nm, purity ≈84%, synthesized by pyrolysis and II: outer diameter d=10÷40 nm, purity ≈94%, synthesized by chemical vapor deposition) were treated by concentrated nitric acid (HNO₃) and by alkaline mixture (NH₄OH+H₂O₂). The alkaline medium as "milder" and less aggressive than nitric acid, was expected to be less destructive and cause minimal structural damage on multiwalled carbon nanotubes surface. Structural changes due to oxidation were observed by the Raman analysis, while the ratio of the intensities of the D and G peak was used to estimate the concentration of defects. Pristine and functionalized multiwalled carbon nanotubes were characterized by thermogravimetric analysis, scanning electron microscopy, ultraviolet-visible spectroscopy and zeta (ζ) spectroscopy. The results showed that functionalization initiates changes in carbon nanotubes structure as well as in their density of states. It also results in carbon nanotubes shortening and exfoliation and decreases their agglomeration tendency. Carbon nanotubes functionalized by both acid and alkaline treatment can successfully replace conventional carbon fibers as fillers in polymer composites for sensing application.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 3; 405-408
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation of carbon nanomaterials over Ni/ZSM-5 catalyst using simplex method algorithm
    Autorzy:
    Majewska, J.
    Michalkiewicz, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1075535.pdf
    Data publikacji:
    2016-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.De
    81.16.Hc
    81.15.Gh
    Opis:
    Carbon nanomaterials were prepared from methane by catalytic decomposition over a nickel-supported ZSM-5 catalyst. The mole ratio of SiO₂ to Al₂O₃ in ZSM-5 was 200-400. The nickel content was varied from 17 to 23 wt% Ni. In order to find the greatest yield and the highest quality of carbon nanomaterials the simplex design method for planning the experiments was applied. Different parameters such as: temperature, methane flow, nitrogen flow and nickel content in the catalyst were evaluated. The carbon nanomaterials were analyzed by the Raman spectroscopy, scanning and transmission electron microscopy, and total organic carbon analyzer.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 1; 153-157
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Production of Y-Ba-Cu-O Nanowires and Nanotubes by Electrochemical Method
    Autorzy:
    Kaya, H.
    Atalay, F.
    Avsar, D.
    Yagmur, V.
    Atalay, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399690.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.Gf
    81.07.De
    81.15.Pq
    74.78.-w
    Opis:
    In this work, the technological aspects of great importance $YBa_2Cu_3O_{7-x}$ superconducting materials were produced in the form of nanotube by electrochemical method. The electrochemical deposition conditions for the Y-Ba-Cu deposition in nanoporous $Al_2O_3$ were investigated. The heat treatment was applied to $Y-Ba-Cu//Al_2O_3$ nanopatterns, to form superconductive phase. The resulting nanostructures were found to be in length 4-5 μm, 177-210 nm in diameter. The produced nanostructures at - 4 V and more positive potentials were Y-Ba-Cu nanowires, while the nanostructures deposited at the more negative potentials were of nanotube form.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 209-211
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical Interference Effects in Visible-Near Infrared Spectral Range for Arrays of Vertically Aligned Multiwalled Carbon Nanotubes
    Autorzy:
    Wąsik, M.
    Judek, J.
    Świtkowski, K.
    Zdrojek, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030331.pdf
    Data publikacji:
    2017-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.20.Ci
    78.67.Ch
    81.07.De
    Opis:
    Based on the reflectance spectra for radiation wavelength from about 380 nm to 1.8 μm, the optical interference effects in vertically aligned multiwalled carbon nanotubes films are studied. We performed the measurements for two complementary polarization states of incoming radiation (s- and p-polarization) for nanotubes arrays sparse enough for interference effects to be possible to observe. By performing the measurements for different wavelengths and incidence angles, we mapped the evolution of interference maxima/minima of reflectance signal. The results from this novel approach indicate that for the radiation polarized perpendicularly to tubes axis (s-polarization), the real part of the effective refractive index can be estimated from the classic Fabry-Pérot model. In order to describe the differences between spectra obtained for s- and p-polarizations we discuss the most important factors that affect the reflectance signal in case of investigated nanotubes arrays.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 2; 232-236
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrochemical Capacitance of Cobalt Oxide Nanotubes on Nickel Foam
    Autorzy:
    Yagmur, V.
    Atalay, F.
    Kaya, H.
    Avcu, D.
    Aydogmus, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399695.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.De
    82.47.Uv
    88.80.fh
    Opis:
    In this study, densely packed $Co_3O_4$ nanotubes for supercapacitors have been obtained by means of chemically depositing cobalt hydroxide within a porous anodic aluminum oxide and then annealed at 360°C. The morphological properties obtained $Co_3O_4$ nanotubes were studied by scanning electron microscopy, the chemical composition was determined by examination of the energy dispersive X-ray spectra. Supercapacitor characteristics such as charging/discharging and impedance (Z) characteristics were also examined.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 215-217
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrochemical Formation of Self-Organized Nanotubular Oxide Layers on Ti13Zr13Nb Alloy for Biomedical Applications
    Autorzy:
    Smołka, A.
    Rodak, K.
    Dercz, G.
    Dudek, K.
    Łosiewicz, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1361071.pdf
    Data publikacji:
    2014-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.85.jj
    81.07.De
    87.85.J-
    Opis:
    In this work, the anodic formation of self-organized nanotubular oxide layers on Ti13Zr13Nb implant alloy was presented. Anodic oxidation was carried out at room temperature in [1 M] $(NH_4)_2SO_4$ solution with 1 wt% content of $NH_4F$. The voltage and time of anodization was 20 V for 120 min, respectively. Under proposed conditions, the best arrangement of nanopores was observed. The physical and chemical properties of the anodized surface of the Ti13Zr13Nb alloy were characterized using grazing incidence X-ray diffraction, scanning transmission electron microscopy, and atomic force microscopy. It was found that diameter of nanopores varied from 10 to 32 nm. Mechanism of the fabrication of the unique 3D tube-shaped nanostructure of $TiO_2$ on the surface of the Ti13Zr13Nb alloy by electrochemical anodization, has been discussed.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 4; 932-935
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrochemical formation of second generation TiO₂ nanotubes on Ti13Nb13Zr alloy for biomedical applications
    Autorzy:
    Stróż, A.
    Dercz, G.
    Chmiela, B.
    Stróż, D.
    Łosiewicz, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1153606.pdf
    Data publikacji:
    2016-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.85.jj
    81.07.De
    82.47.-a
    Opis:
    The aim of this study was to obtain the second generation TiO₂ nanotubes on the Ti13Nb13Zr alloy. Anodic oxidation of the alloy under study was carried out in 1 M (NH₄)₂SO₄ electrolyte under voltage-time conditions of 20 V for 120 min. The morphological parameters of the obtained nanotubes of second generation such as the length (L), internal (D_{i}) and outer (D_{o}) diameter of nanotube were determined. It was found that the anodic oxidation of the Ti13Nb13Zr alloy conducted under proposed conditions allowed to obtain the single-walled nanotubes of the following geometrical parameters: the internal diameter 61 nm, outer diameter 103 nm, and the length 3.9 μm. The total surface area of the single-walled nanotubes was equal to 4.1 μm², and the specific surface area per cm² (A_{s}) was estimated to be 15.6 cm²/cm². Formation mechanism, structure and optimal morphological parameters of the obtained single-walled nanotubes on the Ti13Nb13Zr alloy have been discussed in detail.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 4; 1079-1080
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dispersive Micro Raman Backscattering Spectroscopy Investigation of Arc Discharge Synthesized CNTs Doped by Boron and Nitrogen
    Autorzy:
    Babanejad, S.
    Malekfar, R.
    Seyyed Hosseini, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807785.pdf
    Data publikacji:
    2009-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Fg
    63.22.Gh
    78.67.Ch
    81.07.De
    Opis:
    Raman scattering studies reveal the remarkable structure and the unusual electronic and phonon properties of carbon nanotubes. In this study, we directly produced boron, B, and nitrogen doped carbon nanotubes by using DC-arc discharge method which normally can be employed for producing carbon nanotubes. We performed experiments without using catalysts and in the presence of Ar gas for producing boron doped carbon nanotubes. At the second and third stages and in the presence of $Al_{2}O_{3}$ and MgO nanopowders as catalysts and nitrogen gas were used for producing nitrogen doped carbon nanotubes. In general, our investigation revealed that some major changes caused by B and N dopants can be observed in the related recorded Raman spectra.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 2; 217-220
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of the Silanization Processes on the Properties οf Oxidized Multiwalled Carbon Nanotubes
    Autorzy:
    Scheibe, B.
    Borowiak-Palen, E.
    Kalenczuk, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807640.pdf
    Data publikacji:
    2009-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.65.Mq
    81.07.De
    61.48.De
    65.80.-g
    68.37.Lp
    Opis:
    This paper presents the results of the research on the effect of the two different silanization methods on the thermal and structural properties of oxidized multiwalled carbon nanotubes. As-purified material was oxidized in the mixture of nitric and sulfuric acids. An oxidized material was divided into two parts which underwent two silanization treatments by 3-aminopropyltriethoxysilane (APTES). The first experiment (I) was performed at room temperature in acetone (pH 7) for 30 min. The second experiment (II) involved a hydrolysis of APTES at 40°C in water (pH 4) for 3 h. The functionalization extent of the samples at each step of the preparation was investigated by the Raman spectroscopy. The presence of the functional groups on the nanotubes surface have been studied via the Fourier transform infrared spectroscopy (FT-IR). The quantity of the external moieties introduced on multiwalled carbon nanotubes surface after oxidation process was estimated by the Boehms titration method. The high resolution transmission electron microscopy analysis allowed us to observe the changes of the morphology of the investigated carbon nanotubes. The influence of the silanization processes on the thermal stability of multiwalled carbon nanotubes was thoroughly studied by thermogravimetry analysis. There was observed a significant increase of the thermal stability of the multiwalled carbon nanotubes samples upon silanization treatment in respect of pristine and oxidized multiwalled carbon nanotubes.
    Źródło:
    Acta Physica Polonica A; 2009, 116, S; S-150-S-155
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Increase of Hydrogen Storage Capacity of CNTs by Using Transition Metal, Metal Oxide-CNT Nanocomposites
    Autorzy:
    Larijani, M.
    Safa, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1205209.pdf
    Data publikacji:
    2014-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.82.Rx
    68.37.Lp
    81.07.De
    88.30.R-
    Opis:
    In this paper, we examined the synergetic effect of transition metals or their oxides as decorative agent with carbon nanotubes on the hydrogen storage capacity. The $TiO_2$, Pd, and PdO shell nanoparticles were used as decorative agent on the surface of carbon nanotubes. The samples were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The thermal stability was investigated by thermogravimetric analysis testing. The hydrogen storage capacity was measured by a custom-made Sieverts apparatus. The Pd and $TiO_2$ doped carbon nanotube shows the most marked hydrogen storage capacity, 7 times higher than pristin carbon nanotubes after 30 min storage. The results show that the hydrogen storage capacity of the PdO shell- carbon nanotube composite is very low in comparison with those of two others and does not represent a significant difference with that of carbon nanotubes.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 3; 732-735
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Raman Study on Doped Multiwalled Carbon Nanotubes
    Autorzy:
    Costa, S.
    Borowiak-Palen, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807799.pdf
    Data publikacji:
    2009-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.67.Ch
    73.22.-f
    81.07.De
    61.72.Ww
    63.20.-e
    Opis:
    In the present study we report resonance Raman study on multiwalled carbon nanotubes treated with HCl, $HNO_3$ and $H_2SO_4$. Acids are commonly used in purification procedures in order to remove catalyst particles from the as-produced material. However, it is known that acid treatments in multiwalled carbon nanotubes can induce a surface functionalisation and intercalation of the walls, modifying their electronic properties. Here, we present a comparative study between samples of multiwalled carbon nanotubes modified with the most common acids used in the purification of carbon materials, and the influence of the acid treatment time on their vibronic properties. The samples were analysed via the Raman spectroscopy using the laser length of 785 nm. The presented data reveal the modification of the typical multiwalled carbon nanotubes Raman bands such as: disorder band (D band), the graphite band (G band), and the two-phonon second order Raman band (G' band). The last one shows a broadening effect on its line shape and the appearance of an additional peak. All the treatments enhance the number of defects in the graphitic structure of multiwalled carbon nanotubes.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 1; 32-35
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Resonance Raman Study on Carbon Nanotubes Formation
    Autorzy:
    Steplewska, A.
    Borowiak-Palen, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807842.pdf
    Data publikacji:
    2009-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Fg
    61.46.Np
    81.07.De
    78.30.-j
    61.46.+w
    Opis:
    Carbon nanotubes can be obtained from variety of the molecular precursors in chemical vapor deposition processes. The low growth temperatures strongly increase the compatibility of carbon nanotubes growth with current complementary metal-oxide-silicon technology for carbon nanotubes-based electronics. Here, we show the low temperature growth of multiwalled carbon nanotubes in acetylene chemical vapor deposition with Fe-Co/MgO. The catalyst mix was active already at 450°C. The higher temperatures growth (500°C and 550°C) were also tested in order to estimate the best thermal condition in respect of the sample quality (via thermogravimetric analyzer) and the sample relative purity (via resonance Raman spectroscopy). High resolution transmission electron microscope was used to determine the morphology of the samples.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 1; 93-95
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phase Analysis of Magnetic Inclusions in Nanomaterials Based on Multiwall Carbon Nanotubes
    Autorzy:
    Brzózka, K.
    Krajewski, M.
    Małolepszy, A.
    Stobiński, L.
    Szumiata, T.
    Górka, B.
    Gawroński, M.
    Wasik, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032146.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.Qr
    61.46.Fg
    61.48.De
    75.50.Tt
    75.75.Cd
    81.07.De
    Opis:
    Functionalized multiwall carbon nanotubes as well as nanocomposite based on that material covered by nanoparticles composed of iron oxides were the subject of investigations. In order to identify all iron-bearing phases including those reported on the base of previous X-ray diffraction measurements, the transmission Mössbauer spectroscopy was utilized. The experiments were carried out both at room temperature and also at low temperatures. It was stated that in the investigated nanotubes some impurities were present, originating from the catalyst remains, in form of Fe-C and α -Fe nanoparticles. The Mössbauer spectra collected for the nanocomposite showed a complex shape characteristic of temperature relaxations. The following subspectra related to iron-based phases were identified: sextet attributed to hematite, with hyperfine magnetic field reduced due to the temperature relaxations, sextet corresponding to iron carbide as well as two doublets linked to superparamagnetic hematite and ferrihydrites.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 863-865
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ab Initio Study of Functionalized Carbon Nanotubes
    Autorzy:
    Milowska, K.
    Birowska, M.
    Majewski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791295.pdf
    Data publikacji:
    2009-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    31.15.ae
    31.15.E-
    61.46.Fg
    61.48.De
    73.22.-f
    81.07.De
    Opis:
    In the present paper, we study the stability of (9, 0), (10, 0), (11, 0) carbon nanotubes functionalized with simple organic molecules $-CH_{n}$ (for n = 2, 3, 4). Our studies are based on ab initio calculations within the framework of the density functional theory. We determine binding energies of the functionalized carbon nanotubes and the changes in the geometry and electronic structure caused by the functionalization. We observe the characteristic effects such as rehybridization of the bonds induced by fragments attached to carbon nanotubes and pentagon/heptagon (5/7) defects in $-CH_{2}$ functionalized carbon nanotubes. We study also dependence of the binding energies of the functionalized carbon nanotubes on the density of the adsorbed molecules and diameter of the single-wall carbon nanotubes. Our calculations reveal that the $-CH_{2}$ fragments exhibit the strongest cohesion and we determine the critical density of the $-CH_{2}$ fragments which could be adsorbed.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 5; 841-843
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    $TiO_2$ Nanotube Array as Efficient Transparent Photoanode in Dye-Sensitized Solar Cell with High Electron Lifetime
    Autorzy:
    Lamberti, A.
    Sacco, A.
    Hidalgo, D.
    Bianco, S.
    Manfredi, D.
    Quaglio, M.
    Tresso, E.
    Pirri, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399940.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.63.Bd
    72.20.Jv
    72.40.+w
    73.40.Mr
    88.40.H-
    81.07.De
    Opis:
    In the present work, the fabrication and characterization of non-curling, free-standing $TiO_2$ nanotube membranes and their integration in front-side illuminated dye-sensitized solar cells are reported. Vertically oriented $TiO_2$ nanotube arrays were fabricated by anodic oxidation of a titanium foil. Nanotube membranes were detached from the metallic foil, transferred and bonded on transparent fluorine-doped tin oxide/glass substrates employing a $TiO_2$ sol as a binder. Crystalline phase and morphology of the film were investigated, evidencing the formation of a highly ordered 1D nanotubes carpet, with a pure anatase crystalline structure. $TiO_2$ nanotube-based DSCs were fabricated using reversible microfluidic architecture. The cell performances were studied by I-V electrical characterization, incident-photon-to-electron conversion efficiency, electrochemical impedance spectroscopy and open circuit voltage decay measurements, showing an increase in electron lifetime compared to nanoparticle-based dye-sensitized solar cells.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 376-379
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Complex Magnetoimpedance in Joule-Heated $Co_{71,1}Fe_{3,9}Si_{10}B_{15}$ Microwires
    Autorzy:
    Komova, E.
    Kozar, J.
    Klein, P.
    Varga, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398258.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    81.07.Bc
    75.47.De
    Opis:
    Complex magnetoimpedance study is an alternating current technique that can be used to probe some properties of magnetic materials. We report on complex impedance measurements in low-negative magnetostrictive ferromagnetic CoFeSiB microwire. In these wires, the domain structure consists of two parts: an inner core, with domains oriented to the longitudinal direction of the wire, and an outer shell with circumferentially oriented domains. This magnetic structure is modified by AC current flowing through the microwire which produces an additional circumferential magnetic field $H_Φ$ and significantly affects magnetic structure inside the wires. The additional circular magnetization process in wires was studied by impedance measurements as a function of the amplitude and the frequency of the AC current after gradual Joule heating. Changes in the magnetization processes are reflected in the real permeability values and loss factor values.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 705-707
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural and Optical Characterization of GaN/AlGaN Single Quantum Disk Nanorods
    Autorzy:
    Almokhtar, M.
    Emura, S.
    Tambo, H.
    Hasegawa, S.
    Asahi, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400040.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Km
    78.67.De
    81.07.Vb
    Opis:
    GaN/AlGaN single quantum disks on GaN nanorods were grown on Si (001) substrate with native $SiO_2$ layer by a plasma-assisted molecular-beam epitaxy under nitrogen-rich conditions. The transmission electron microscopy observations show single GaN nanorods images with an average thickness of 4 nm for the GaN single quantum disk and nanorod diameter of 15 nm. The observed photoluminescence spectra at 8 K show a peak at 3.475 eV, attributed to an exciton recombination in GaN. A strong peak was observed at 3.542 eV. This peak is attributed to the quantum confinement of excitons in the GaN quantum disks.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 473-475
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electronic Band Structure of Coiled Carbon Nanotubes
    Autorzy:
    Milošević, I.
    Damnjanović, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1503008.pdf
    Data publikacji:
    2011-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.48.De
    73.22.-f
    81.07.-b
    Opis:
    More than fifteen years have passed since the first report of experimental evidence of regularly coiled carbon nanotubes, but, the structure, formation mechanism and theoretical aspects of these nanotubes still remain unresolved. We propose model of hexagonal, helically coiled single wall carbon nanotubes, determine their line group symmetry and calculate electronic band structure of the relaxed configurations by means of fully symmetry adopted density functional tight binding method implemented into the POLSym code. Electrical properties of the straight and coiled carbon nanotubes of different chiralities are compared and analyzed.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 2; 221-223
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elasticity Study of PAAm-κ C Composite Prepared in Various κ C Content and Measured at Several Temperatures
    Autorzy:
    Evingür, G.
    Pekcan, Ö.
    Powiązania:
    https://bibliotekanauki.pl/articles/1401880.pdf
    Data publikacji:
    2015-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    62.20.de
    81.05.Mh
    07.20.Dt
    Opis:
    Polyacrylamide (PAAm)-kappa carrageenan (κC) composite gels were prepared via free radical crosslinking copolymerization with various (w/v) percentages of κC in the range between 0.5 and 3 (w/v)% of κC. Elasticity properties such as stress, strain and compressive elastic modulus, S of these composite gels were studied in various κC content and at several temperatures. The content and temperature dependence of the compressive elastic modulus, S of the swollen PAAm-κC composite gels due to volume phase transition were produced by using tensile testing technique. It is understood that the compressive elastic modulus was found to decrease up to 1 (w/v)% of κC, and then increase by increasing κC contents, at constant temperatures. The composite preserves the ability to undergo the volume phase transition and its compressive elastic modulus is found to be strongly dependent on the κC content and temperature. It is observed that the compressive elastic modulus increased when temperature is increased up to 40°C and then decreases below this temperature for all composite gels. However, PAAm-κC composite gel presented lower values for the compressive elastic modulus, showing a minima at 40°C for 1 (w/v)% of κC content gel.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 3; 331-335
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    GMI Effect in Annealed $Fe_{40}Ni_{38}Mo_{4}B_{18}$ Microwires
    Autorzy:
    Komova, E.
    Šidik, F.
    Klein, P.
    Varga, R.
    Vazquez, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1367050.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    81.07.Bc
    75.47.De
    Opis:
    Amorphous glass-coated microwires are ideal material for miniaturized applications for sensing the temperature, stress and magnetic field. One of the key parameters for future applications is their time and thermal stability. It has been shown that stability can be improved by using nanocrystalline materials that combine good soft magnetic properties of amorphous matrix with high structural stability of crystalline grains. Such nanocrystalline materials are usually obtained by annealing of amorphous precursor. In the given contribution, the influence of dc current annealing on the domain structure and GMI effect in amorphous and nanocrystalline $Fe_{40}Ni_{38}Mo_{4}B_{18}$ magnetic microwire has been studied. The annealing induces additional circular magnetic anisotropy, stress relief and structure homogenization. However, the increase of magnetostriction results in the decrease of GMI. Annealing at optimum crystallisation temperature results in an increase of the relative permeability due to the formation of the nanosized grains. Consequently, GMI amplitude is comparable to that of as-cast state.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 74-75
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and Characterisation of Silicon/Carbon Nanotube Composite Electrodes for Li-Ion Battery Systems
    Autorzy:
    Cetinkaya, T.
    Tocoglu, U.
    Cevher, O.
    Guler, M.
    Akbulut, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399951.pdf
    Data publikacji:
    2013-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.uf
    61.48.De
    81.20.Ev
    81.07.-b
    Opis:
    Silicon powders and different amounts of multiwalled carbon nanotube were mechanically alloyed in polyacrynitrile solution via high speed planetary ball milling. Produced composite was characterised via X-ray diffraction pattern, scanning electron microscopy, energy dispersive spectroscopy and thermogravimetric analysis.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 2; 398-400
    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:
    Study of the structure and thermal properties of intermetallics from Fe-Al system
    Autorzy:
    Śmiglewicz, A.
    Rodak, K.
    Tomaszewska, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1112888.pdf
    Data publikacji:
    2016-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.70.Pg
    65.40.De
    65.60.+a
    07.20.-n
    Opis:
    Selected alloys from the Fe-Al system are included into a group of materials on a matrix of intermetallic phases, and characteristic properties result from it and they constitute a resultant between properties of superalloys and ceramic materials. These materials are characterized, inter alia, by capacity for operating at elevated temperatures, as well as good strength related properties and resistance to oxidation and corrosion at an increased temperature. In addition, a low cost of alloy components and low density caused by aluminium content are their advantages. The basic reasons limiting application of alloys from Fe-Al system as construction materials are current: their low plasticity at room temperature, propensity for brittle cracking, low resistance at elevated temperature, and insufficient creep resistance. This unfavorable characteristics may be improved by adding to alloys such elements as molybdenum, zirconium, carbon, and boron, reducing the size of grains, increasing their purity, stabilizing the solid solution, and causing changes in phase transition temperatures. These alloys may be successfully manufactured by classic melting accompanied with refinement remelting, and ingot casting. In spite of additions and microadditions, grain refining of the initial structure of ingots manufactured in that way is rarely achieved, mainly because of low castability and high casting contraction. In this work we presented the results of structure analysis and investigations of the dilatometric study alloys on the base Fe-Al system. The alloys were obtained by classic casting technique. The studies were carried out on samples after casting and annealing. The phase transformation and thermal expansion investigations of the alloys from Fe-Al system with concentration of Fe-58Al were presented. The linear thermal expansion α was calculated by standard method. The α coefficient was noticed as a temperature function.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 4; 1004-1006
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    III-Nitride Nanostructures for Infrared Optoelectronics
    Autorzy:
    Monroy, E.
    Guillot, F.
    Leconte, S.
    Bellet-Amalric, E.
    Nevou, L.
    Doyennette, L.
    Tchernycheva, M.
    Julien, F. H.
    Baumann, E.
    Giorgetta, F.
    Hofstetter, D.
    Dang, Le Si
    Powiązania:
    https://bibliotekanauki.pl/articles/2046980.pdf
    Data publikacji:
    2006-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.21.Fg
    78.67.De
    85.60.Gz
    85.35.Be
    81.15.Hi
    81.07.St
    Opis:
    Thanks to their large conduction band offset (~1.8 eV for the GaN/AlN system) and subpicosecond intersubband scattering rates, III-nitride heterostructures in the form of quantum wells or quantum dots are excellent candidates for high-speed unipolar devices operating at optical-fiber telecommunication wavelengths, and relying on the quantum confinement of electrons. In this work, we present the plasma-assisted molecular-beam epitaxial growth of quantum well infrared photodetector structures. The growth of Si-doped GaN/AlN multiple quantum well structures is optimized by controlling substrate temperature, metal excess and growth interruptions. Structural characterization confirms a reduction of the interface roughness to the monolayer scale. P-polarized intersubband absorption peaks covering the 1.33-1.91μm wavelength range are measured on samples with quantum well thickness varying from 1 to 2.5 nm. Complete intersubband photodetectors have been grown on conductive AlGaN claddings, the Al mole fraction of the cladding matching the average Al content of the active region. Photovoltage measurements reveal a narrow (~90 meV) detection peak at 1.39μm at room temperature.
    Źródło:
    Acta Physica Polonica A; 2006, 110, 3; 295-301
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary Investigations into the Purification and Functionalization of Multiwall Carbon Nanotubes
    Autorzy:
    Trykowski, G.
    Biniak, S.
    Stobinski, L.
    Lesiak, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1536523.pdf
    Data publikacji:
    2010-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.48.De
    81.16.Be
    07.57.Ty
    82.80-d
    68.37.Hk
    Opis:
    The purification and functionalization of commercial multiwall carbon nanotubes was investigated. Carbon nanotubes (CNT CO., Ltd, Korea) were treated with boiling concentrated HNO_3 under a reflux condenser for about 50 h at 120°C in order to purify and oxidize the raw material. The oxidized multiwall carbon nanotubes were rinsed with deionized water until stabilization of the filtrate pH. Measurement techniques included elemental analysis (CHN), scanning electron microscopy with energy dispersive X-ray spectrometer, inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy and thermal analysis. With the measurement techniques used the following information was obtained: CHN analysis provided information about the quantitative composition of the following elements carbon, hydrogen, nitrogen, scanning electron microscopy imaging provided information on shape, thickness and length of the nanotubes, energy dispersive X-ray spectrometry analysis of information about surface atomic composition of the quantitative analysis, inductively coupled plasma mass spectrometry quantitative analysis of the atomic composition (metals, especially Fe, Al), the Fourier transform infrared studies provided information about qualitative analysis of surface functional groups $C_{x}O_{y}H_{z}$ (COOH, OH, COO) and thermal gravimetric-differential thermal analysis - quantitative analysis of thermal decomposition products. It was found that oxidation leads to the removal of amorphous carbon and forms mainly carboxylic functional groups linked to the nanotubes. The Fourier transform infrared spectra indicate the presence of some other structures, like ketone (quinone), acid anhydride, ether and epoxy groups. Nitric acid treatment also effectively removes aluminum oxide catalyst and iron catalyst from commercial multiwall carbon nanotubes.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 3; 515-518
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Correlation Between Elastic Properties and AFM Images of Nanocoatings on Polymers
    Autorzy:
    Gümüş, S.
    Polat, Ş.
    Lackner, J.
    Waldhauser, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193923.pdf
    Data publikacji:
    2015-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.-b
    68.55.am
    68.55.J-
    68.37.Ps
    62.20.de
    68.60.Bs
    Opis:
    In a biomimetic approach for designing implants, both the physical properties (such as topography, elasticity, roughness, hydrophilicity, charges etc.) and the chemical structure of the artificial biomaterial should be considered, since they affect the adhesion of proteins in the nanometer-scale and of the cells in micro-scale at the interface. In this case, surface modification of biomaterials plays a major role because of the expectations from the material surface. These may be realized by changing the surface chemistry, physically or chemically, or by coating it with a material having a certain chemical composition. In this study, surface properties like topography and roughness, and mechanical properties like elastic modulus and hardness are determined for nanocoated materials.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 4; 1142-1144
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-26 z 26

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