Temat: 61.46.-w - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Diffraction Studies of Nanocrystals: Theory and Experiment
Autorzy:: Palosz, B.
Grzanka, E.
Gierlotka, S.
Stel'makh, S.
Pielaszek, R.
Bismayer, U.
Neuefeind, J.
Weber, H.-P.
Palosz, W.
Tematy:: 61.46.+w; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2035453.pdf Link otwiera się w nowym oknie
Opis:: Based on theoretical calculations of powder diffraction data it is shown that the assumption of the infinite crystal lattice for small particles is not justified, leads to significant changes of the diffraction patterns, and may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called "apparent lattice parameter", alp, is proposed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: An Icosahedral Quasicrystal as a Packing of Regular Tetrahedra
Autorzy:: Fang, F.
Kovacs, J.
Sadler, G.
Irwin, K.
Tematy:: 61.44.Br
61.46.-w; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1202974.pdf Link otwiera się w nowym oknie
Opis:: We present the construction of a dense, quasicrystalline packing of regular tetrahedra with icosahedral symmetry. This quasicrystalline packing was achieved through two independent approaches. The first approach originates in the Elser-Sloane 4D quasicrystal. A 3D slice of the quasicrystal contains a few types of prototiles. An initial structure is obtained by decorating these prototiles with tetrahedra. This initial structure is then modified using the Elser-Sloane quasicrystal itself as a guide. The second approach proceeds by decorating the prolate and oblate rhombohedra in a 3-dimensional Ammann tiling. The resulting quasicrystal has a packing density of 59.783%. We also show a variant of the quasicrystal that has just 10 "plane classes" (compared with the 190 of the original), defined as the total number of distinct orientations of the planes in which the faces of the tetrahedra are contained. This small number of plane classes was achieved by a certain "golden rotation" of the tetrahedra.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: The 5:7 Member of the Spin-Ladder Series in the Bi-Sr-Ca-Cu-O System
Autorzy:: Zaremba, O.
Shcherban, O.
Akselrud, L.
Gladyshevskii, R.
Banfi, F.
Giannini, E.
Tematy:: 61.46.-w
61.66.-f; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1550056.pdf Link otwiera się w nowym oknie
Opis:: The crystal structure of the $(Bi_{0.02}Sr_{0.39}Ca_{0.59})_{10}Cu_{17}O_{29}$ spin-ladder compound was determined from single-crystal X-ray diffraction data. The precursor powder was prepared from stoichiometric amounts of $SrCO_{3},$ $CaCO_{3},$ $CuO,$ and $Bi_{2}O_{3}$ by calcination at 820°C for 20 h and pressed to form a rod used for the crystal growth. The travelling-solvent-floating-zone method was applied in an image furnace to grow large single crystals. The composite commensurate structure was solved and refined in space group F222, Pearson symbol oF224, a = 11.340(2), b = 12.829(2), c = 19.441(3) Å, Z = 4. The composite incommensurate structure of the $(Bi_{0.02}Sr_{0.39}Ca_{0.59})_{10}Cu_{17}O_{29}$ compound was solved and refined in the (3+1)-space group F222 (00γ), a = 11.340(2), b = 12.829(2), c_1 = 2.7773(4), c_2 = 3.8882(6) Å, q = 0.7143.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Generation and Relaxation of Microstrains in GaN Nanocrystals under Extreme Pressures
Autorzy:: Grzanka, E.
Palosz, B.
Gierlotka, S.
Pielaszek, R.
Bismayer, U.
Janik, J.
Wells, J.
Palosz, F.
Porsch, F.
Tematy:: 61.46.+w
81.07.Wx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2035466.pdf Link otwiera się w nowym oknie
Opis:: Nanocrystalline powders of GaN with grain sizes ranging from 2 to 30 nm were examined under high external pressures by in situ diffraction techniques in a diamond anvil cell at DESY (HASYLAB, Station F3). The experiments on densification of pure powders under high pressure were performed without a pressure medium. The mechanism of generation and relaxation of internal strains and their distribution in nanoparticles was deduced from the Bragg reflections recorded in situ under high pressures at room temperature. The microstrain was calculated from the full-width at half-maximum (FWHM) values of the Bragg lines. It was found that microstrains in GaN crystallites are generated and subsequently relaxed by two mechanisms: generation of stacking faults and change of the size and shape of the grains occurring under external stress.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: X-ray Synchrotron Studies of Nanostructure Formation in High Temperature - Pressure Treated Silicon Implanted with Hydrogen
Autorzy:: Wieteska, K.
Wierzchowski, W.
Graeff, W.
Misiuk, A.
Barcz, A.
Bryja, L.
Popov, V. P.
Tematy:: 68.55.-a
61.46.+w; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2035493.pdf Link otwiera się w nowym oknie
Opis:: The effects of various high temperature-pressure treatments in Czochralski grown silicon (Cz-Si) implanted with 130 keV hydrogen to the dose of 4times10$\text{}^{16}$ cm$\text{}^{-2}$ were investigated using synchrotron X-ray topographic methods and rocking curve measurements. The high temperature- pressure processes included 10 h annealing at 450°C, 650°C, and 725°C at argon pressure 12 kbar and 1 bar. The topographic investigations were performed with projection and section methods in back-reflection and transmission geometry. It was found that annealing resulted in significantly reduced strain induced by the implantation, which became undetectable with presently used very sensitive synchrotron arrangement. A significant difference between the Cz-Si:H samples annealed at high and atmospheric pressure was observed. In the first case a distinct topographic contrast attributed to the formation of comparatively larger inclusions was observed. This effect was different at different temperatures. The samples annealed at enhanced pressure were more uniform and often produced significant interference effects.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Structure and Physicomechanical Properties of Nanostructured (TiHfZrNbVTa)N Coatings after Implantation of High Fluences of N⁺ (10¹⁸ cm¯²)
Autorzy:: Pogrebnjak, A.
Bondar, O.
Borba, S.
Piotrowska, K.
Boiko, O.
Tematy:: 61.46.-w
62.20.Qp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030134.pdf Link otwiera się w nowym oknie
Opis:: New classes of high-entropy alloys, which consist of at least 5 main elements with atomic concentrations 5-35 at.%, are under great interest in modern material science. It is also very important to explore the limits of resistance of high-entropy alloy nitrides to implantation by high-energy atoms. Structure and properties of nanostructured multicomponent (TiHfZrNbVTa)N coatings were investigated before and after ion implantation. We used the Rutherford backscattering, scanning electron microscopy with energy dispersive X-ray spectroscopy, high resolution transmission electron microscopy and scanning transmission electron microscopy with local microanalysis, X-ray diffraction and nanoindentation for investigations. Due to the high-fluence ion implantation (N⁺, the fluence was 10¹⁸ cm¯²) a multiphase structure was formed in the surface layer of the coating. This structure consisted of amorphous, nanocrystalline and initial nanostructured phases with small sizes of nanograins. Two phases were formed in the depth of the coating: fcc and hcp (with a small volume fraction). Nitrogen concentration reached 90 at.% near the surface and decreased with the depth. Nanohardness of the as-deposited coatings varied from 27 to 34 GPa depending on the deposition conditions. However, hardness decreased to a value of 12 GPa of the depth of the projected range after ion implantation and increased to 23 GPa for deeper layers.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Fabrication and Research of Superhard (Zr-Ti-Cr-Nb)N Coatings
Autorzy:: Bondar, O.
Postolnyi, B.
Kravchenko, Yu.
Shypylenko, A.
Sobol, O.
Beresnev, V.
Kuzmenko, A.
Zukowski, P.
Tematy:: 61.46.-w
62.20.Qp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1402215.pdf Link otwiera się w nowym oknie
Opis:: This work presents the results of (Zr-Ti-Cr-Nb)N superhard coatings research. The samples were fabricated by the vacuum-arc deposition method (Arc-PVD). Structure, composition and properties of these coatings were studied. The study of coatings was carried out using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Hardness measurements and adhesion tests were performed. The coatings thickness was up to 6.2 μ m, nanocrystallites sizes ranged from 4 to 7.3 nm. Values of hardness and cohesive strength were H=43.7 GPa and $L_{C}$=62.06 N, respectively. The optimal conditions for coating deposition were found.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 8.

Tytuł:: Curved Surfaces in Disordered Carbons by High Energy X-ray Scattering
Autorzy:: Burian, A.
Szczygielska, A.
Kołoczek, J.
Dore, J.
Honkimaki, V.
Duber, S.
Tematy:: 61.10.-i
61.10.Eq
61.46.+w; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2030692.pdf Link otwiera się w nowym oknie
Opis:: Disordered carbons prepared by slow pyrolysis of saccharose and anthracene and subsequent heat treatment at 1000ºC and 2300ºC have been studied by high energy X-ray diffraction. Computer simulations of the powder diffraction patterns of fullerenes, nanotubes and carbon models have been compared with the experimental data after conversion to real space via the Fourier transform. The presence of fullerene- and nanotube-like fragments with non-six membered rings in the investigated samples has been deduced by detailed analysis of the radial distribution functions of the saccharose- and anthracene-based carbons and related to resistance to graphitization of the saccharose-based carbons and to stability of the growing crystallites in the case of the anthracene-based carbons. The obtained results are compared to high resolution electron microscopy and Raman studies.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Structural Studies of Carbon Nanotubes and Related Materials by Neutron and X-Ray Diffraction
Autorzy:: Dore, J.
Burian, A.
Tomita, S.
Tematy:: 61.46.+w
61.12.-q
61.10.-i; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2014376.pdf Link otwiera się w nowym oknie
Opis:: X-ray and neutron diffraction measurements are presented for a number of carbon samples prepared by different techniques. The information obtained from diffraction studies is presented in relation to other types of investigation, particularly in relation to electron microscopy. The characteristics of the graphene sheets are discussed in relation to these features.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Fe Clusters in Fe Intercalated Fullerite
Autorzy:: Sobczak, E.
Żymierska, D.
Byszewski, P.
Traverse, A.
Tematy:: 61.10.Ht
61.46.+w
71.20.Tx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1955842.pdf Link otwiera się w nowym oknie
Opis:: The local structure around Fe ions in the C$\text{}_{60}$Fe$\text{}_{2}$ fullerites before and after heat treatment in temperature of 850 K was investigated by means of Fe K edge X-ray absorption near edge structure and extended X-ray absorption near edge structure methods. The X-ray absorption measurements were performed at liquid nitrogen temperature using synchrotron radiation in transmission mode. The X-ray absorption near edge structure and extended X-ray absorption near edge structure studies showed that the heat treatment of the C$\text{}_{60}$Fe$\text{}_{2}$ fullerite at temperature 850 K causing an irreversible transition from monoclinic to fcc structure is accompanied with changes in the state of Fe ions, part of them forms clusters in bcc structure, while others turn to Fe$\text{}^{3+}$ ions bonded to fullerenes.
Dostawca treści:: Biblioteka Nauki

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