Temat: 71.20.Dg - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: The Systematic Variation of Optical Properties of Alkali Halides: an Ab Initio Study
Autorzy:: Gonçalves, G. C.
Lalic, M. V.
Malta, O. L.
Tematy:: 71.20.Dg
78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2047877.pdf Link otwiera się w nowym oknie
Opis:: In this paper we study a correlation between the optical properties, electronic structure and anion-cation electronegativity difference in three groups of alkali halides MX (M = Li, Na, K; X = F, Cl, Br, I). The electronic structure was calculated by first-principle, density-functional theory based full-potential linear augmented plane wave method. Then the complex dielectric function was computed, allowing determination of the optical absorption spectra in all compounds, up to incident radiation energy of 40 eV. The results were interpreted in terms of calculated band structures and correlated with the electronegativity difference in each compound, which was estimated on the basis of topological theory of Bader.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The Structural and Electronic Properties of BaO under Epitaxial Strains: First-Principles Calculations
Autorzy:: Yang, Xiong
Wang, Ying
Chen, Yifei
Yan, Huiyu
Tematy:: 71.20.Dg
71.70.Fk
71.15.Mb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1191222.pdf Link otwiera się w nowym oknie
Opis:: The structural and electronic properties of alkaline-earth oxide BaO under epitaxial strains are investigated using a first principles density functional theory. The electronic structure is particularly sensitive to the compressive or tensile strain, e.g., the splitting of energy band, the increase of the total density of state, and the shift of the partial density of states. Especially, the trends in the variation of the optical band gap are predicted by two different exchange-correlation potential schemes. Our results indicate that the optical band gaps undergo a decrease for both compressive and tensile strains.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 3.

Tytuł:: Fermi Surface-Brillouin Zone Interactions in 2/1-2/1-2/1 Bergman-Type Approximant $Na_{27}Au_{27}Ga_{31}$
Autorzy:: Mizutani, U.
Sato, H.
Inukai, M.
Zijlstra, E.
Lin, Q.
Corbett, J.
Miller, G.
Tematy:: 71.23.Ft
71.20.Dg
71.15.Mb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1373341.pdf Link otwiera się w nowym oknie
Opis:: The X-ray diffraction studies on a newly synthesized $Na_{26}Au_{25}Ga_{29}$ single crystal revealed the formation of a single phase 2/1-2/1-2/1 Bergman-type approximant and the presence of Au/Ga mixed occupancies in its unit cell containing 680 atoms. The structure model of the 2/1-2/1-2/1 approximant with composition $Na_{27}Au_{27}Ga_{31}$ was constructed by eliminating the chemical disorder with a minimum sacrifice of composition displacement. The full potential linearized augmented plane wave electronic structure calculations with subsequent full potential linearized augmented plane wave-Fourier analysis were performed for the 2/1-2/1-2/1 approximant $Na_{27}Au_{27}Ga_{31}$ with space group Pa3̅. The square of the Fermi diameter $(2k_{F})^2$, electrons per atom ratio e/a and the critical reciprocal lattice vector $|G|^2$ are determined. A shallow pseudogap at the Fermi level was interpreted as originating from interference of electrons having $(2k_{F})^2$=109.2±1.0 with sets of lattice planes with $|G|^2$'s centered at 108. The effective e/a value for the compound is found to be 1.76 in good agreement with 1.73 derived from a composition average of $(e/a)_{Na}$=1.0, $(e/a)_{Au}$=1.0 and $(e/a)_{Ga}$=3.0.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 4.

Tytuł:: Formation of Dislocation Structure in LiF Crystals Irradiated with Swift Heavy Ions under Oblique Incidence
Autorzy:: Russakova, A.
Akilbekov, A.
Dauletbekova, A.
Baizhumanov, M.
Tematy:: 42.88.+h
61.80.Jh
71.20.Dg; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1365710.pdf Link otwiera się w nowym oknie
Opis:: The structural modifications of LiF irradiated with swift heavy ions under oblique angles have been investigated using AFM, SEM, chemical etching, nanoindentation and optical absorption spectroscopy. LiF crystals were irradiated under incidence angles of 30 and 70 degrees with 2.2 GeV Au (fluence 5 × $10^{11}$ ions $cm^{-2}$) and 150 MeV Kr ions (fluence $10^{12}-10^{14}$ ions $cm^{-2}$). Structural study on sample cross-sections shows that two damage regions, (1) nanostructured zone and (2) dislocation rich zone, which are typical for irradiations at normal incidence, appear also in samples irradiated under oblique angles. However in the latter case a more complex structure is formed that leads to stronger ion-induced hardening.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 5.

Tytuł:: Symmetry Induced Half-Metallic Alkaline Earth Ferromagnets
Autorzy:: Adamowicz, L.
Wierzbicki, M.
Tematy:: 71.15.Mb
71.20.Dg
72.25.Ba
75.10.Lp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1810473.pdf Link otwiera się w nowym oknie
Opis:: Search for new half-metallic ferromagnetic binary compounds composed of alkaline earth and III (boron) or IV (carbon) elements is reported. Ab initio all-electron density functional theory calculations in the generalised gradient approximation indicate possibility of half-metallic ferromagnetism. This is a new class of theoretically predicted hypothetical materials, without transition metal elements, not as yet discovered experimentally. Ferromagnetism is expected to be induced by suitable crystalline structure with lattice constant above some critical value. The predominant p electrons mechanism seems to be responsible for the formation and interactions of localised magnetic moments on boron or carbon atoms.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

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.
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; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1995573.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 7.

Tytuł:: Reconstruction of the Exchange Integrals Map of ScFe₄Al₈ Magnetic Structure
Autorzy:: Rećko, K.
Dobrzyński, L.
Waliszewski, J.
Szymański, K.
Tematy:: 61.05.fm
71.20.Be
71.70.Gm
75.10.Dg
75.30.Et; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1386376.pdf Link otwiera się w nowym oknie
Opis:: The influence of the dipolar as well as crystal field interaction as the main reasons of the noncollinearity and incommensurability of the 3d-3d-3p alloy belonging to ThMn₁₂ family is investigated. Available data on the single crystal neutron scattering experiments for ScFe₄Al₈ compound are discussed. The values and directions of the spin ordering found by magnetic diffraction are compared to that one derived from ground state configurations obtained by a simulated annealing algorithm.
Dostawca treści:: Biblioteka Nauki

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