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Wyszukujesz frazę "61.66.f" wg kryterium: Temat


Tytuł:
Infinite Body Centered Cubic Network of Identical Resistors
Autorzy:
Asad, Jihad
Diab, A.
Owaidat, M.
Hijjawi, R.
Khalifeh, J.
Powiązania:
https://bibliotekanauki.pl/articles/1206306.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Ah
61.50.+f
61.66.f
84.37.+q
05.50.+q
04.60.Nc
63.90.+t
84.30.Bv
02.90.+p
Opis:
We express the equivalent resistance between the origin (0,0,0) and any other lattice site ($n_1$,$n_2$,$n_3$) in an infinite body centered cubic network consisting of identical resistors each of resistance R rationally in terms of known values $b_{0}$ and π. The equivalent resistance is then calculated. For large separations two asymptotic formulae for the resistance are presented and some numerical results with analysis are given.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 60-64
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disorder and Diffusion in Mayenite
Autorzy:
Boysen, H.
Kaiser-Bischoff, I.
Lerch, M.
Berendts, S.
Hoelzel, M.
Senyshyn, A.
Powiązania:
https://bibliotekanauki.pl/articles/1550024.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.-j
61.66.-f
61.05.fm
Opis:
Mayenite, $Ca_{12}Al_{14}O_{33}$, has attracted enormous attention for novel technological applications after the discovery of its high oxygen ionic conductivity. The crystal structure consists of a calcium-aluminate framework, comprising 32 of the 33 oxygen anions. The remaining oxygen is distributed over 1/6 of large cages within the framework. The true structure is heavily disordered and usually non-stoichiometric due to the presence of extra anions and is presented for four samples: pure oxygen mayenite (O-mayenite), partly (O/N-mayenite) and fully (N-mayenite) exchanged by nitrogen and doped with iron (Fe-mayenite). All samples were investigated by neutron powder diffraction up to 1050°C. Data were analysed by the Rietveld method and by difference Fourier methods. As prepared O-mayenite contains $O_{2}^{-}$ and $OH^{-}$, N- and O/N-mayenite also $NH_{2}^{-}$, $NH^{2-}$ and $N^{3-}$, while Fe-mayenite was free of extra radicals. In O- and N-mayenite the extra species are lost under vacuum conditions above ca. 700°C, whereas O/N-mayenite retained $NH_{2}^{-}$ up to high temperatures. Diffusion of oxygen proceeds via a jump-like interstitialcy process involving exchange of the "free" oxygen with framework oxygen, coupled to relaxations of Ca ions. In O/N-mayenite $NH_{2}^{-}$ diffuses via interstitial process. In Fe-mayenite encaged oxygen is "invisible" due to extreme delocalisation or loss.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 38-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Diffraction Tomography and Dynamical Refinement for Crystal-Structure Characterization of Nanocrystalline Materials
Autorzy:
Corrêa, C.
Klementová, M.
Palatinus, L.
Powiązania:
https://bibliotekanauki.pl/articles/1402113.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.J-
61.66.-f
61.46.Km
Opis:
Three-dimensional electron diffraction tomography allows one to obtain structure information from nanocrystals. However, in order to get accurate results the dynamical theory must be used due to the strong dynamical interaction between electrons and matter. Full structure refinement using dynamical theory has been in use for some time, in spite of being hampered by the fact that the intensities are very sensitive to variations of thickness and of the orientation of the sample. A remedy to this problem is the technique called precession electron diffraction. The use of precession electron diffraction in combination with electron diffraction tomography results in more accurate structure parameters and lower figures of merit in the structure refinement. The principles of electron diffraction tomography, precession electron diffraction and dynamical refinement will be demonstrated on the structural analysis of a nanowire of Ni₃Si₂.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 651-653
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First-Principles Study of Structural, Elastic and Mechanical Properties of Zinc-Blende Boron Nitride (B3-BN)
Autorzy:
Daoud, S.
Loucif, K.
Bioud, N.
Lebgaa, N.
Powiązania:
https://bibliotekanauki.pl/articles/1419742.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
45.10.-b
62.20.D-
61.66.-f
62.20.de
81.40.Jj
31.15.E-
Opis:
First principles study of structural, elastic properties and anisotropy effect on the mechanical parameters of the zinc-blende boron nitride has been performed using the pseudopotential plane wave method based on density functional theory with the Teter and Pade exchange-correlation functional of the local density approximation. The equilibrium lattice constant, molecular and crystal densities, bond length, the independent elastic constants, bulk modulus and its pressure derivatives, compressibility, shear modulus, internal strain parameter, isotropy factor, compliance constants, the Debye temperature, Young's modulus, Poisson's ratio, the Lamé constants and sound velocity for directions within the important crystallographic planes of this compound are obtained and analyzed in comparison with the available theoretical data reported in the literature.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 109-115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A System of B-C-N-O: Synthesis, Characterization and Determination of Unit Cell Parameters
Autorzy:
Gül, G.
Kurtuluş, F.
Powiązania:
https://bibliotekanauki.pl/articles/1033375.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Ea
61.66.-f
61.66.Fn
84.40.-x
Opis:
Boron-rich solids are good candidates to apply instead of diamond. Boron has a unique crystal structure and compounds of it are resistant to heat treatment. These structures have light density, high hardness, and chemically inertness. Also, boron compounds display thermal and electronic properties as a thermoelectric power at high temperatures. A boron, carbon, nitrogen, and oxygen containing compound was synthesized for the first time by classical microwave method using elemental amorphous boron, active carbon, and urea with 1:1:1 molar ratio. The compound is crystallized in monoclinic system with unit cell parameters a=12.9575 Å, b=9.3264 Å, c=9.6529 Å, β =113.277° which are calculated by POWD indexing program. The X-ray diffraction, POWD, the Fourier transform infrared, scanning electron microscopy/energy X-ray diffraction spectroscopy and thermogravimetric/different thermal analysis were achieved.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 36-38
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR and Spectral Studies of a Molecular and Crystal Structure of Cu (3,5-dimethylpyridine)$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{2}$
Autorzy:
Hoffmann, S. K.
Goher, M. A. S.
Hilczer, W.
Goslar, J.
Hafez, A. K.
Powiązania:
https://bibliotekanauki.pl/articles/1930620.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Ea
61.66.-f
76.30.Da
Opis:
X-band single crystal EPR, IR and UV-VIS data are used to deduce a molecular and crystal structure of a new compound with a chemical formula Cu(3,5-dimethylpyridine)$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{2}$. EPR shows that four magnetically inequivalent molecules exist in the crystal unit cell of C$\text{}_{4v}$ symmetry. IR spectra suggested that both monodentate and bidentate NO$\text{}_{3}$-groups exist in the crystal. A most probable Cu(II) complex geometry with d$\text{}_{x²-y²}$ ground state is a square pyramid with three nitrogens from 3,5-dimethylpyridine molecules and one oxygen from monodentate nitrato group in a basal plane and an oxygen from NO$\text{}_{3}$-group in apical position. There exists a chemical contact between complexes as it is indicated by the exchange interaction with |J| ≤ 1 cm$\text{}^{-1}$. It suggests that square pyramid complexes are arranged in polymeric chains with semi-coordination of bidentate NO$\text{}_{3}$-group to the adjacent Cu(II) ion. An extended analysis of an exchange averaging effect between EPR lines from two and four Cu(II) sites is presented with equations relating molecular and crystal g-factors.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 517-530
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Bond Valence Model to Stability of RE Oxycompounds
Autorzy:
Hölsä, J.
Koski, K.
Lamminmäki, R.-J.
Rahiala, H.
Säilynoja, E.
Powiązania:
https://bibliotekanauki.pl/articles/1963262.pdf
Data publikacji:
1997-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.40.-z
61.66.-f
61.10.-i
Opis:
The bond valence model was used to study the stability of the non-stoichiometric $LaO_{1-x}F_{1+2x}$ phases, the solid solubility in the ($La_{1-x}Gd_{x}$) OCl system and the phase transformation in the REOCl ($RE^{3+}=La^{3+} -Nd^{3+}, Sm^{3+}-Gd^{3+}, Ho^{3+}, and Y^{3+}$) series. The stability of the non-stoichiometric $LaO_{1-x}F_{1+2x}$ (0 ≤ x ≤ 0.3) phase decreases with increasing excess fluoride. The global instability index values close to 0.2 indicate the instability of the non-stoichiometric phase. The relative stability of the ($La_{1-x}Gd_{x}$)OCl (0 ≤ x ≤ 1.0) solid solutions achieved its minimum in the middle of the series. However, the X-ray powder diffraction results indicated complete solid solubility in the whole ($La_{1-x}Gd_{x}$)OCl series and no phase separation was observed. The bond valence model was used to explain the structural transformation from the tetragonal oxychlorides, REOCl (RE = La-Er, and Y), to hexagonal beyond ErOCl. The calculated global instability index values did not show any clear trend across the REOCl series probably due to the inaccuracies and incoherencies in the original structural data.
Źródło:
Acta Physica Polonica A; 1997, 91, 3; 563-568
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Some Structural and Spectroscopic Aspects of Rare Earth Oxycompounds
Autorzy:
Hölsä, J.
Säilynoja, E.
Porcher, P.
Powiązania:
https://bibliotekanauki.pl/articles/1952800.pdf
Data publikacji:
1996-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.10.-i
61.12.-q
61.50.-f
61.66.Fn
Opis:
The aim of this account is to present the use and the advantages of different experimental and theoretical methods in the study of the structural and spectroscopic properties of rare earth (RE) oxyfluorides. The structural characterization was carried out with the X-ray and neutron powder diffraction techniques combined with the analysis of the acquired data with the Rietveld profile refinement method. The detailed spectroscopic studies were also used by employing the optical absorption and luminescence as well as inelastic neutron scattering data. Simple spectroscopic measurements gave, however, only qualitative description of the spectroscopic properties studied. More sophisticated and quantitative means was obtained by the application of the phenomenological crystal field theory to the spectroscopic data. On the other hand, the structural data was also used as initial input to electrostatic point charge calculation in order to extract the spectroscopic information. The structural and spectroscopic studies comprised the verification of the exact crystal and energy level structures and the characterization of the different interactions modifying the spectroscopic properties of the RE$\text{}^{3+}$ ions. Finally, the results from the theoretical model were used to explain the evolution of the crystal field effect on the 4f$\text{}^{N}$ energy level structure of the RE$\text{}^{3+}$ ion in the RE oxyfluorides series.
Źródło:
Acta Physica Polonica A; 1996, 90, 6; 1193-1201
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibration and Luminescence Spectroscopic Investigations of the Alkali Rare Earth Double Phosphates M$\text{}_{3}$(RE,Eu)(PO$\text{}_{4}$)$\text{}_{2}$ (M=K, Rb; RE=La, Gd)
Autorzy:
Kloss, M.
Schwarz, L.
Hölsä, J. P. K.
Powiązania:
https://bibliotekanauki.pl/articles/1995573.pdf
Data publikacji:
1999-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
61.66.Fn
63.20.-e
71.20.Dg
71.20.Eh
71.70.-d
78.30.-j
78.55.-m
Opis:
The room temperature IR- and Raman spectra of the different M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ (M = K, Rb; RE = La, Eu, Gd) double phosphates were analysed and used to interpret the vibronic side band structure in the photoluminescence spectra. The intraconfigurational 4f-4f electronic transitions in the photoluminescence spectra of the Eu$\text{}^{3+}$ doped M$\text{}_{3}$RE(PO$\text{}_{4}$)$\text{}_{2}$ were analysed in detail. The crystal field fine structure of the $\text{}^{5}$D$\text{}_{0}$ → $\text{}^{7}$F$\text{}_{J}$ (J=0-4) transitions was analysed accounting for the information on the crystal structure. The effect of the temperature as well as the alkali host cation was evaluated. Finally, a preliminary crystal field energy level scheme for the $\text{}^{7}$F$\text{}_{J}$ (J=0-4) ground term was deduced from the analysis of the photo-luminescence as well as IR- and Raman spectra.
Źródło:
Acta Physica Polonica A; 1999, 95, 3; 343-349
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Stabilities and Elastic Constants of EuX (X = O, S, Se, and Te) Compounds at High Pressure
Autorzy:
Kong, B.
Zhou, Z.
Sun, X.
Zhang, L.
Ling-Hu, R.
Powiązania:
https://bibliotekanauki.pl/articles/1400144.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.-f
46.70.-p
61.43.-j
75.50.-y
Opis:
The structural stabilities, elastic properties and charge transfers of EuX (X = O, S, Se, Te) compounds as a function of pressure are investigated extensively using first-principles calculations. The ground-state parameters, such as lattice constants, bulk modulus are predicted and compared with the available data, our results are satisfactory. The calculated phase transition pressures from the NaCl-type (B1) structure to the CsCl-type (B2) structure for EuX (X = O, S, Se, Te) also accord with the experiments. Particularly, the elastic constants of EuX (X = O, S, Se, Te) under zero pressure and high pressure are simulated appropriately for the first time via density functional theory. The softening behaviors of the elastic shear modulus $C_{44}$ under pressure for the B1 phase of EuX (X = O, S, Se, Te) are captured, which should be responsible for the pressure-induced structural phase transition in the EuX system. It is also suggested that the softening behavior might be induced partly by the p → d and f → d electron transfers of Eu atom under pressure. In addition, the aggregate elastic modulus (B, G, E), Poisson's ratio (σ), Debye temperature $\Theta p_{D}$ are also successfully obtained for both B1 and B2 phases of EuX.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 720-727
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Calculations of Cohesive and Electronic Properties of Quaternary AlGaInN Alloys
Autorzy:
Łopuszyński, M.
Bartoszek, J.
Majewski, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2047722.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Dk
61.66.-f
62.20.Dc
64.30.+t
Opis:
We present theoretical studies of the AlGaInN nitride quaternary alloys. The studies are based on ab initio calculations performed within the density functional theory and virtual crystal approximation. The equilibrium lattice constants, bulk moduli, and elastic constants were calculated for the whole possible range of concentrations of the alloy constituents. The theoretical values were then fitted with second- and third-order polynomials. For all properties studied, the considerable bowing was observed.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 449-454
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mössbauer Spectrometry in FeMoCuB-Type Nanocrystalline Alloys
Autorzy:
Miglierini, M.
Powiązania:
https://bibliotekanauki.pl/articles/1813519.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
61.46.+w
61.66.-f
76.80.+y
Opis:
The applicability of the Mössbauer spectrometry to the study of $Fe_{91-x}Mo_8Cu_1B_x$ (x = 12, 15, 17) nanocrystalline alloys prepared by controlled annealing of ribbon-shaped amorphous precursors is demonstrated. Differences between both surfaces of the ribbons are pointed out to be due to preparation conditions. Conclusions from the Mössbauer spectrometry are supported by diffraction of synchrotron radiation, X-ray diffraction, and atomic field microscopy investigations.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 47-50
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Domain h Type Collective Dimerization of Graphite and Possible $sp^2$ rightarrow $sp^3$ Transition Induced by Inter h Layer Charge Transfer Excitations in the Visible Region
Autorzy:
Radosinski, L.
Ostasiewicz, K.
Luty, T.
Radosz, A.
Nasu, K.
Powiązania:
https://bibliotekanauki.pl/articles/1536487.pdf
Data publikacji:
2010-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.30.Hd
61.66.-f
Opis:
We theoretically study possible domain-type collective dimerizations of graphite induced by inter-layer charge transfer excitations in the visible region. Using the semiempirical Brenner theory, we have calculated the adiabatic energy along the path that starts from original two distant graphite layers, but finally reaches the dimerized domain which consists of about 100 carbons with inter-layer σ-bonds. The energy barrier between this new domain and the starting graphite is shown to be of the order of 1 eV, being easily overcome by applying a few visible photons. We have also shown the optimal path of transformation via step by step increase of the domain size.
Źródło:
Acta Physica Polonica A; 2010, 118, 3; 500-506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoinduced Conversion of Hybridization in Graphite
Autorzy:
Radosinski, L.
Luty, T.
Nasu, K.
Ohnishi, H.
Nishioka, K.
Radosz, A.
Wójt, D.
Powiązania:
https://bibliotekanauki.pl/articles/1490005.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.30.Hd
61.66.-f
Opis:
Recent experiments indicate that a photostimulated graphite with a femtosecond laser pulse results in the formation of a stable domain with sp^3 like interlayer bonds. By means of the energy barrier minimization and molecular dynamics using the empirical Brenner potential we study a geometrical structure of the new phase. We clarify proliferation of the initial domain and prove that the overall process is a multiphoton one. Furthermore, we present a model describing the initial transformation - an interlayer charge transfer resulting in the localization of an exciton-like state. The local density approximation electronic structure analysis reveals that the electronic state of the new phase is an insulator immersed in semimetal. We study by means of the long-range carbon bond order potential the effect of the existence of the new phase on the surrounding graphite and propose a new mid step structure on the path of a photoinduced graphite-diamond conversion.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 359-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Temperature Crystal Structure Behaviour of Complex Yttrium Aluminium Oxides YAlO_3 and Y_3Al_5O_{12}
Autorzy:
Senyshyn, A.
Vasylechko, L.
Powiązania:
https://bibliotekanauki.pl/articles/1399474.pdf
Data publikacji:
2013-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
61.05.F-
65.40.De
65.60.+a
63.70.+h
Opis:
Crystal structures of two yttrium aluminium oxides, namely $YAlO_3$ and $Y_3Al_5O_{12}$, were investigated in the temperature range 3.4-300 K by high-resolution neutron powder diffraction. Neither traces of phase transformations nor discontinuous changes of physical properties were observed. Thermal expansion of yttrium aluminium oxides was evaluated in terms of 1st order Grüneisen approximation, where the Debye temperatures and the Grüneisen parameters have been estimated for both compositions. Anomalies in the thermal expansion of yttrium aluminium perovskite have been observed and modelled using the Einstein oscillator with negative Grüneisen parameter. Extended bond length analysis revealed significant thermally-driven modifications of the aluminium-oxygen framework.
Źródło:
Acta Physica Polonica A; 2013, 124, 2; 329-335
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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