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Wyszukujesz frazę "81.07.De" wg kryterium: Wszystkie pola


Tytuł:
Topographical, Magnetic and Optical Studies of (II,Mn)VI Quantum Structures Grown on (Ga,Mn)As
Autorzy:
Butkutė, R.
Aleszkiewicz, M.
Janik, E.
Cywiński, G.
Wojnar, P.
Däweritz, L.
Primus, J.
De Boeck, J.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036853.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Hi
07.79.Pk
78.55.-m
Opis:
We report on an overgrowth of quantum structures consisting of diluted magnetic semiconductor CdMnTe quantum wells with non-magnetic barriers made of CdMgTe or ZnTe on ferromagnetic MnAs and GaMnAs films by molecular beam epitaxy. Atomic force microscopy images of the quantum structures grown on MnAs demonstrated the existence of two types of regions on the surface: protruded islands with micrometric sizes, surrounded by areas of small-scale roughness. Magnetic force microscopy study of these samples revealed a magnetic domain structure only on the above mentioned islands. The (II,Mn)VI quantum wells grown on GaMnAs films exhibited relatively smooth surface, but no magnetic force microscopy signal was measurable either before or after magnetizing the sample. In the luminescence spectra of all our quantum structures the emission attributed to CdMnTe quantum wells was observed. The influence of magnetization on the luminescence line position was investigated.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 649-657
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:
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:
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:
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:
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:
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:
Application of Statistical Image Analysis in Quantification of Neutron Radiography Images of Drying
Autorzy:
Fijał-Kirejczyk, I.
Milczarek, J.
Żołądek-Nowak, J.
de Beer, F.
Radebe, M.
Nothnagel, G.
Powiązania:
https://bibliotekanauki.pl/articles/1419614.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.59.bf
07.05.Pj
61.05.Tv
81.05.Rm
47.56.+r
47.55.nb
Opis:
The statistical approach to the thermal neutron radiography picture analysis is applied to evaluation of the experimental results obtained for drying of rectangular and cylindrical samples of granulated and rigid porous materials. We have shown that the time dependence of the standard deviation of image brightness reflects the appearance and motion of the drying front observed during second period of the drying process. The results are discussed within a simple two-region model of the drying sample image.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 410-414
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:
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:
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:
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:
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

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