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Wyszukujesz frazę "61.82.Fd" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
$\text{}^{57}Fe$ Mössbauer Spectroscopy οf Radiation Damaged Allanites
Autorzy:
Malczewski, D.
Grabias, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811896.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.45.+x
61.82.Fd
64.60.My
76.80.+y
Opis:
Metamict minerals contain radioactive elements that degrade the crystal structure of the minerals. The degradation occurs primarily through progressive overlapping recoil nuclei collision cascades from α-decays of $\text{}^{238}U$, $\text{}^{232}Th$, $\text{}^{235}U$ and their daughter products. We report the results of $\text{}^{57}Fe$ Mössbauer spectroscopy, gamma-ray spectrometry and microprobe analysis of three partially metamict allanites, $(Ca,Ce,REE)_2(Fe^{2+},Fe^{3+})$$(Al,Fe^{3+})_2O[Si_2O_7][SiO_4](OH)$ where REE stands for rare earth elements. The samples were collected in pegmatites from Reno, Nevada (USA), Franklin, New Jersey (USA) and Nya Bastnas Field (Sweden). The absorbed α-dose for these minerals was found to range from $5.8×10^{14}$ α-decay/mg for the allanite from Reno to $1.9×10^{15}$ α-decay/mg for the allanite from Franklin. The Mössbauer spectra show a decrease in the $Fe^{2+}$ doublet intensity with increasing absorbed α-dose. We also observe an increase in the line widths of the $Fe^{2+}$ and $Fe^{3+}$ doublets with increasing absorbed α-dose.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1683-1690
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Application of High Pressure in Physics and Technology of III-V Nitrides
Autorzy:
Grzegory, I.
Leszczyński, M.
Krukowski, S.
Perlin, P.
Suski, T.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2030388.pdf
Data publikacji:
2001-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.-h
78.66.Fd
73.61.Ey
82.60.Lf
78.55.Cr
Opis:
Due to high bonding energy of N$\text{}_{2}$ molecule, the III-V semiconducting nitrides, especially GaN and InN require high N$\text{}_{2}$ pressure to be stable at high temperatures necessary for growth of high quality single crystals. Physical properties of GaN-Ga(l)-N$\text{}_{2}$ system are discussed in the paper. On the basis of the experimental equilibrium p-T-x data and the quantum-mechanical modeling of interaction of N$\text{}_{2}$ molecule with liquid Ga surface, the conditions for crystallization of GaN were established. The crystals obtained under high pressure are of the best structural quality, having dislocation density as low as 10-100 cm$\text{}^{-2}$ which is several orders of magnitude better than in any other crystals of GaN. The method allows to grow both n-type substrate crystals for optoelectronics and highly resistive crystals for electronic applications. The physical properties of the pressure grown GaN measured to characterize both point defects and extended defects in the crystal lattice are discussed in the paper. A special attention is paid to the application of high pressure to reveal the nature of the point defects in the crystals and electric fields in GaN-based quantum structures. Due to their very high structural quality, the pressure grown crystals are excellent substrates for epitaxial growth of quantum structures. It opens new possibilities for optoelectronic devices, especially short wavelength high power lasers and efficient UV light emitting diodes. This is due to the strong reduction in dislocation densities in relation to existing structures (10$\text{}^{6}$-10$\text{}^{8}$ cm$\text{}^{-2}$) which are grown on strongly mismatched sapphire and SiC substrates. The experimental results on the epitaxial growth and physical properties of GaN-based device structures supporting above conclusions are discussed in the paper. The current development of blue laser technology in High Pressure Research Center is shortly reviewed.
Źródło:
Acta Physica Polonica A; 2001, 100, Supplement; 57-109
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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