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Wyszukujesz frazę "MgB2" wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
Tytuł:
Thermoelectric Power of $MgB_2$ Single Crystals Doped with Holes and Electrons
Autorzy:
Oganisian, K.
Rogacki, K.
Sulkowski, C.
Zhigadlo, N.
Katrych, S.
Karpinski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1812320.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Fy
74.70.Ad
74.62.Dh
Opis:
The thermoelectric power of $MgB_2$ single crystals, non-substituted, single-substituted with C, and co-substituted with C and Li, was investigated in the temperature range from 10 to 300 K. Both the in-plane $(S_ab)$ and the out-of-plane $(S_c)$ thermoelectric powers are positive for non-substituted crystals and both $S_{ab}$ and $S_c$ change a sign for crystals doped with electrons when C is substituted for B in the amount larger than 6 at.%. The substitution of C, which supplies electrons mainly into the σ band, reduces the thermoelectric power anisotropy, most likely by increasing the interband scattering. When Li is additionally co-substituted for Mg, $S_ab$ remains unchanged but $S_c$ increases substantially. The Li substitution donates holes into the π band rather than into the σ band and in this way modifies the π band properties, including the possible increase in the intraband scattering.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 191-195
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Nano-SiC Doping on the Superconducting Critical Parameters in $MgB_2$/Fe Wires and Tapes
Autorzy:
Gajda, D.
Zaleski, A.
Morawski, A.
Kario, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813696.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
74.25.Sv
Opis:
In this paper the results of critical current measurements for $MgB_2$ wires and tapes in iron sheath with and without nano-SiC doping are presented. We focus on power-in-tube processing technique, using both in situ and ex situ methods. In situ $MgB_2$ wires and tapes were fabricated from $MgH_2$ and B or Mg and B powders. The methods such as hydrostatic extrusion and rolling were used. The samples were annealed under high Ar gas pressure (hot isostatic pressing) at 750°C and 1.0 GPa for 40 min. It was found that critical current of $MgB_2$/Fe superconducting wire or tape with nano-SiC dopant increased in higher magnetic field values in comparison to pure $MgB_2$. A significant difference of $J_c$ in tapes made by in situ way from $MgH_2$ and Mg were found.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 371-374
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Transport Critical Current Densities of $MgB_2//Fe//Cu$ Multifilament Tapes without Any Intermediate Annealing
Autorzy:
Yucel, E.
Terzioglu, C.
Varilci, A.
Gencer, A.
Belenli, I.
Powiązania:
https://bibliotekanauki.pl/articles/1489874.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Ad
84.71.Mn
74.62.-c
74.25.Sv
74.25.F-
Opis:
We have fabricated superconducting 6 and 7 filaments $MgB_2//Fe//Cu$ tapes by ex situ powder-in-tube method using Cu-sheath without any intermediate annealing. Properties of two different multicore $MgB_2//Fe//Cu$ tapes annealed at 900C for 2 h in high purity argon gas atmosphere were compared. The samples were characterized using scanning electron microscope, X-ray diffraction, electron dispersive spectroscopy, optical microscopy, critical transition temperature, transport critical current density, and magnetic measurements. Transport critical current densities of the 6 and 7 filaments tapes were found to be 450 A/cm^2 and 190 A/cm^2 at 20 K, respectively. From X-ray diffraction measurements, lattice parameters a and c were determined. From dc resistivity measurements, the connectivity between grains was investigated by using Rowell's connectivity analysis.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 660-665
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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