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Wyszukujesz frazę "81.07.+b" wg kryterium: Temat


Tytuł:
Preparation and Characterization of d.c.-Plated Nanocrystalline Nickel Deposits
Autorzy:
Szeptycka, B.
Derewnicka, D.
Powiązania:
https://bibliotekanauki.pl/articles/2035480.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
68.37.Lp
68.60.-p
Opis:
The microstructure, microhardness, corrosion, and wear resistance of d.c.-plated Ni electrodeposits prepared from different types of electrolyzing Watts-type baths, without or with organic compounds, ceramic powder - SiC and polymer - polytetrafluoroethylene (PTFE), on Cu substrate, which was subsequently removed from the deposits, were investigated. With the change of the type of bath, the deposit grain size was found to decrease markedly, e.g. deposits with an average grain size of about 50 nm could be produced from a bath containing 45 g/dm$\text{}^{3}$ Ni$\text{}^{2}$+ ions, 5 g/dm$\text{}^{3}$ SiC, and 20 g/dm$\text{}^{3}$ PTFE. The surface morphology on the bath side of the electrodeposited Ni or Ni-SiC-PTFE foils was characteristic of the type of bath, and its roughness correlated well with the observed grain size. Microhardness and wear resistance increased with decreasing grain size, as expected. On discussing the factors controlling deposit grain size, it is concluded that the Ni$\text{}^{2+}$ ion content in the bath and the presence of organic compounds may have a decisive role.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 199-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Topographic Peculiarities of the Formation of Nanosized Particles from Metallopolymers
Autorzy:
Pomogailo, A. D.
Dzhardimalieva, G. I.
Rosenberg, A. S.
Powiązania:
https://bibliotekanauki.pl/articles/2035462.pdf
Data publikacji:
2002-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.07.Bc
Opis:
The morphology of solid phase products of thermal transformation of transition metal acrylates or its cocrystallites is studied. The thermal transformation of the metal-containing monomers studied consists in dehydration, solid phase polymerization and thermolysis process. The topography of the initial compounds and solid phase products of thermal decay, as well as their composition, are analyzed by optical and electron microscopies. The average particle sizes, d$\text{}_{EM}$, are: 6.0-13.0 nm in the case of FeAcr$\text{}_{6}$ (based on the data of electron diffraction, the main product is Fe$\text{}_{3}$O$\text{}_{4}$), 6.0 nm for FeCoAcr$\text{}_{8}$ and Fe$\text{}_{2}$CoAcr$\text{}_{14}$ (Fe$\text{}_{3}$O$\text{}_{4}$, CoO, Fe$\text{}_{2}$CoO$\text{}_{4}$), and 6 nm for CoMal$\text{}_{2}$ (CoO). The material formed consists of nanosized metal particles uniformly allotted in polymer matrix.
Źródło:
Acta Physica Polonica A; 2002, 102, 1; 135-145
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Characterization of Two-Dimensional Ordered Arrays of Metallic Nanoparticles
Autorzy:
Kandulski, W.
Kosiorek, A.
Rybczyński, J.
Bauman, D.
Giersig, M.
Powiązania:
https://bibliotekanauki.pl/articles/2036995.pdf
Data publikacji:
2003-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
Opis:
A method of obtaining large-scale 2D arrays of ordered metallic nanoparticles is presented. The arrays were prepared using nanosphere lithography based on the self-assembly of latex particles on a water surface. Using 496 nm and 1040 nm diameter particles, it was possible to prepare arrays of over one cm$\text{}^{2}$, with defect-free areas of over 50μ m$\text{}^{2}$. By the evaporation of nickel or gold, periodic metallic particle arrays were produced. Modification of the particle array morphology was also shown by using double-layered masks. Computer simulated mask models were used to reveal interesting morphologies obtainable by the application of multilayered masks.
Źródło:
Acta Physica Polonica A; 2003, 104, 5; 495-502
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Physical Properties of SiC-GaAs Nano-Composites
Autorzy:
Kalisz, G.
Grzanka, E.
Wasik, D.
Świderska-Środa, A.
Gierlotka, S.
Borysiuk, J.
Kamińska, M.
Twardowski, A.
Pałosz, B.
Powiązania:
https://bibliotekanauki.pl/articles/2043724.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
07.35.+k
Opis:
Nano-composites consisting of primary phase of hard nanocrystalline SiC matrix and the secondary nanocrystalline semiconductor (GaAs) phase were obtained by high-pressure zone infiltration. The synthesis process occurs in three stages: (i) at room temperature the nanopowder of SiC is compacted along with GaAs under high pressure up to 8 GPa, (ii) the temperature is increased above the melting point of GaAs up to 1600~K and, the pores are being filled with liquid, (iii) upon cooling GaAs nanocrystallites grow in the pores. Synthesis of nano-composites was performed using a toroid-type high-pressure apparatus (IHPP of the Polish Academy of Sciences, Warsaw) and six-anvil cubic press (MAX-80 at HASYLAB, Hamburg). X-ray diffraction studies were performed using a laboratory D5000 Siemens diffractometer. Phase composition, grain size, and macrostrains present in the synthesized materials were examined. Microstructure of the composites was characterized using scanning electron microscopy and high resolution transmission electron microscopy. Far-infrared reflectivity measurements were used to determine built-in strain.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 717-721
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Dimensional Thermoelectricity
Autorzy:
Heremans, J. P.
Powiązania:
https://bibliotekanauki.pl/articles/2043708.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
73.63.-b
81.07.-b
Opis:
Thermoelectric materials are used as solid-state heat pumps and as power generators. The low efficiency of devices based on conventional bulk thermoelectric materials confines their applications to niches in which their advantages in compactness and controllability outweigh that drawback. Recent developments in nanotechnologies have led to the development of thermoelectric nano-materials with double the efficiency of the best bulk materials, opening several new classes of applications for thermoelectric energy conversion technology. We review here first the physical mechanisms that result in the superior thermoelectric performance of low-dimensional solids, compared to bulk thermoelectric materials: they are a reduction of the lattice thermal conductivity, and an increase in the Seebeck coefficient S for a given carrier density. The second part of this review summarizes experimental results obtained on macroscopic arrays of bismuth, antimony, and zinc nanowires with diameters ranging from 200 to 7 nm. We show how size-quantization effects greatly increase S for a given carrier concentration, as long as the diameter of the nanowires remains above 9 nm, below which localization effects start dominating. In a third part, we give data on PbTe nanocomposites, particularly bulk samples containing 30~nm diameter Pb inclusions. These inclusions affect the electron scattering in such a way as to again increase the Seebeck coefficient.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 609-634
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Ga$\text{}_{2}$O$\text{}_{3}$ Nanobelts Synthesized by the Thermal Annealing of GaN Powders
Autorzy:
Kim, Hyoun Woo
Kim, Nam Ho
Powiązania:
https://bibliotekanauki.pl/articles/2041772.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.05.Hd
Opis:
We synthesized the uniform monoclinic gallium oxide (Ga$\text{}_{2}$O$\text{}_{3}$) nanobelts by a simple thermal annealing of GaN powders. The as-syn-thesized nanobelts were rectangular in cross-sectional shape with width ranging from 100 to 700 nm. The length direction of the nanobelt was along [010]. Photoluminescence measurement under excitation at 325 nm showed that the Ga$\text{}_{ }$2O$\text{}_{3}$ nanobelts had a blue emission at around 454 nm.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 346-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement and Analysis of the Positron Annihilation Lifetime Spectra for Mesoporous Silica
Autorzy:
Zaleski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047164.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
41.75.Fr
Opis:
Positron annihilation lifetime spectroscopy as a technique of porous materials investigation is still under development. Both measurement conditions and lifetime spectra analysis methods have to be adapted to the requirements of positron porosimetry. If complex positron annihilation lifetime spectra of porous materials are processed, numerical methods of lifetime spectra analysis have to be used with a particular care. Among various methods of positron annihilation lifetime spectra analysis available, the most popular ones were tested implemented in programs MELT and LT. It was found, from the simulated spectra study, that a large number of counts in a spectrum is needed to obtain reliable results of analysis. Even then only an approximate solution is available. Determination of the approximation nature helps in a further interpretation of the results and in positron annihilation lifetime spectrometer setting adequate to the problem. For this purpose, a few complex spectra obtained from positron beam facility were tested. The results show a negligible influence of resolution function on long lifetime components, while the precise estimation of the background level is crucial. Also some distortions caused by imperfection of numerical analysis methods are pointed out.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 729-738
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$SiO_x$ Nanowires Produced on Molybdenum-Coated Si Substrates
Autorzy:
Kim, H.
Lee, J.
Yang, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813396.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
78.55.-m
Opis:
We synthesized $SiO_x$ nanowires with diameters of 30-140 nm, for the first time by the simple heating of the Mo-coated Si substrates. X-ray diffraction, selected area electron diffraction, and energy-dispersive X-ray spectroscopy indicated that the nanowires were in an amorphous state, comprising Si and O only. Fitting the photoluminescence spectrum with Gaussian functions revealed that the nanowires exhibited significant photoluminescence intensities near blue and green light regions. We extensively discussed the possible growth mechanism of $SiO_x$ nanowires.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 1017-1020
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Catalyst-Free Growth of Magnesium Oxide Whiskers and Their Characteristics
Autorzy:
Kim, H.
Kong, M.
Yang, J.
Powiązania:
https://bibliotekanauki.pl/articles/1813397.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
78.55.-m
Opis:
This study reports the production of magnesium oxide (MgO) whiskers on silicon (Si) substrates by the thermal heating of $MgB_2$ powders. We investigated the structural properties of the as-synthesized whiskers by using X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and scanning electron microscopy. The product consisted of one-dimensional whiskers with a square cross-section. The whiskers had a single-crystalline cubic structure of MgO. The photoluminescence measurement with the Gaussian fitting exhibited visible light emission bands centered at 2.39 eV and 2.91 eV. We proposed the growth of MgO whiskers to follow the vapor-solid mechanism.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 1021-1024
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modifications in Near-Surface Layer of Transparent Dielectrics Ionized by Ultrashort Laser Pulses
Autorzy:
Komolov, V.
Przhibel'skii, S.
Powiązania:
https://bibliotekanauki.pl/articles/1813399.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.16.-c
Opis:
Formation of spatially non-uniform mechanical tension in a transparent solid due to the lattice ionization under the intensive ultrashort laser pulses action is predicted and theoretically described. Within the framework of the continual theory of elasticity the estimation of both average values of deformation tensor and its variations in solid dielectric with non-uniform random distribution of ions was carried out. It was shown that three possible types of medium modification can arise in solid depending on its ionization degree and the thickness of ionized layer. Since the Coulomb fields inside ionized layer can be non-uniform, all three types of structuring can arise in solid simultaneously.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 1029-1034
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NdFeB Permanent Magnets with Various Nd Content
Autorzy:
Žák, T.
Talijan, N.
Ćosović, V.
Grujić, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813649.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
76.80.+y
75.50.-y
81.07.-b
81.40.Rs
Opis:
Three kinds of commercial Nd-Fe-B based materials were compared using $\text{}^{57}Fe$ Mössbauer spectroscopy and X-ray analysis: near the $Nd_2Fe_{14}B$ stoichiometry and with both lowered and raised Nd content. Magnetically hard $Nd_2Fe_{14}B$ is present in all three materials. In the Nd-low material it is accompanied with the magnetically soft $Fe_3B$ phase, building the nanocomposite structure. In the Nd-rich sample the overstoichiometric Nd atoms seem to build separate phase of Fe-Nd solid solution. None of the materials contain significant content of phases degrading magnetic characteristics, with except of minor $Nd_{1.1}Fe_4B_4$ one.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 279-282
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Porosimetry Studies of Template Removal from As-Synthesized MCM-41 Silica
Autorzy:
Zaleski, R.
Wawryszczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1812554.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
Opis:
The course of template removal from MCM-41 pores was investigated by positron annihilation lifetime spectroscopy. Two methods of removal were the object of interest: a decarbonisation after standard calcination procedure and a novel procedure - pyrolysis in vacuum. The shapes of positron lifetime spectra of decarbonised sample are determined by positronium quenching caused by presence of carbon deposit on the surface. Positron annihilation lifetime spectroscopy allows also monitoring the evolution of empty space inside pores. During pyrolysis no conductive carbon is produced, so consecutive stages of template material transformation are easy to observe. In the case of pyrolysis the effect of pore emptying is obtained at temperature 500 K, lower comparing to calcination and decarbonisation (820 K).
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1543-1550
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis by Wet Chemical Method and Characterization of Nanocrystalline ZnO Doped with $Fe_2O_3$
Autorzy:
Narkiewicz, U.
Sibera, D.
Kuryliszyn-Kudelska, I.
Kilański, L.
Dobrowolski, W.
Romčević, N.
Powiązania:
https://bibliotekanauki.pl/articles/1812407.pdf
Data publikacji:
2008-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
75.75.+a
78.67.Bf
Opis:
Nanocrystalline samples of ZnO doped with $Fe_2O_3$ were synthetized by wet chemical method. The series of ZnO nanosized samples in the wide range of $Fe_2O_3$ concentration (from 5 wt.% to 95 wt.%) was prepared by precipitation from nitrate solutions using ammonia. The phase composition of the samples was determined using X-ray diffraction measurements. The phases of hexagonal ZnO, and/or rhombohedric $Fe_2O_3$, and/or $ZnFe_2O_4$ were identified. The mean crystalline size of nanocrystals, determined with the use of Scherrer's formula, varied from 8 to 52 nm. The preliminary micro-Raman spectroscopy measurements were performed. The observed features are typical of Fe doped ZnO nanoparticles. The magnetic measurements revealed the presence of different types of magnetic behavior. For samples with high $Fe_2O_3$ contents (above 70 wt.%) the ferromagnetic ordering was observed at room temperature. For samples with lower $Fe_2O_3$ contents we observed the phenomenon of superparamagnetism above the blocking temperature.
Źródło:
Acta Physica Polonica A; 2008, 113, 6; 1695-1700
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of ZnSe Nanolayers by Spectroscopic Ellipsometry
Autorzy:
Šćepanović, M.
Grujić-Brojčin, M.
Nesheva, D.
Levi, Z.
Bineva, I.
Popović, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1795712.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.15.-z
81.05.Dz
78.30.-j
07.60.Fs
68.55.-a
Opis:
Single layers of ZnSe with thicknesses of 30, 40, 50, 70 and 100 nm are deposited at room substrate temperature by thermal evaporation of ZnSe powder in vacuum. The layers surface morphology has been investigated by atomic force microscopy. Structural characterization by the Raman scattering measurement revealed the existence of randomly oriented crystalline ZnSe particles in all layers, and the presence of amorphous phase in layers thinner than 100 nm. The ellipsometric measurements were performed in the range from 1.5 to 5 eV at room temperature in air. To interpret the experimental results, the Bruggeman effective medium approximation of dielectric function of ZnSe layers has been used, representing the layers as different mixtures of crystalline ZnSe (c-ZnSe), amorphous ZnSe (a-ZnSe), and voids. The assumption of polycrystalline ZnSe layers modeled as mixture of porous c-ZnSe (with volume fraction of voids ≈ 0.17) and a-ZnSe gives the best fit of ellipsometric experimental data. Single layer thicknesses similar to those expected from preparation conditions have been obtained by this fitting procedure. It has been also found that decrease in the layer thickness causes an increase of the volume fraction of a-ZnSe. Thus, c-ZnSe/a-ZnSe ratio, porosity and layer thickness obtained by spectroscopic ellipsometry, provides useful information about crystallinity and micro-/nanostructure of ZnSe nanolayers.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 708-711
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrochemical Deposition of Nanowires in Porous Alumina
Autorzy:
Kalska-Szostko, B.
Brancewicz, E.
Mazalski, P.
Sveklo, J.
Olszewski, W.
Szymański, K.
Sidor, A.
Powiązania:
https://bibliotekanauki.pl/articles/1809497.pdf
Data publikacji:
2009-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.45.-h
62.23.Hj
82.45.Qr
81.07.-b
75.75.+a
Opis:
Electrochemical deposition is a very efficient method for producing many types of modern materials. The method is not expensive and does not have a limit for sample size. In our work the preparation of Ni, Co and Fe nanowires is presented. The obtained nanowires had different diameter and length which were tunable by template porous material and time of deposition, respectively. The quality of the prepared wires was dependent also on deposition mode. The smallest wires of the diameter around 40 nm were prepared in porous anodic alumina oxide obtained from oxalic acid. The largest ones, around 120 nm, were produced in phosphoric acid. The length could be as large as the thickness of the oxide and reached up to about 1 μm. The morphology of wires was studied by atomic force microscopy and scanning electron microscopy. The magnetic characterization was done with usage of magnetic force microscopy and the Mössbauer spectroscopy. The wires show magnetization along their growth direction.
Źródło:
Acta Physica Polonica A; 2009, 115, 2; 542-544
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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