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Titre du Document
Flux Pinning Optimization of MgB2 Bulk Samples Prepared Using High-Energy Ball Milling and Addition of TaB2
MgB2 is considered to be an important conductor for applications. Optimizing flux pinning in these conductors can improve their critical currents. Doping can influence flux pinning efficiency and grain connectivity, and also affect the resistivity, upper critical field and critical temperature. This study was designed to attempt the doping of MgB2 on the Mg sites with metal-diborides using high-energy ball milling. MgB2 samples were prepared by milling pre-reacted MgB2 and TaB2 powders using a Spex 8000M mill with WC jars and balls in a nitrogen-filled glove box. The mixing concentration in (Mg1-xTax)B2 was up to x = 0.10. Samples were removed from the WC jars after milling times up to 4000 minutes and formed into pellets using cold isostatic pressing. The pellets were heat treated in a hot isostatic press (HIP) at 1000° C under a pressure of 30 kpsi for 24 hours. The influence that milling time and TaB2 addition had on the microstructure and the resulting superconducting properties of TaB2-added MgB2 is discussed. Improvement of Jc at high magnetic fields and of pinning could be obtained in milled samples with added TaB2. The sample with added 5at.%TaB2 and milled for 300 minutes showed values of Jc ~ 7 × 105 A/cm2 and Fp ~ 14 GN/m3 at 2 T, 4.2 K. The milled and TaB2-mixed samples showed higher values of μ0 Hirr than the unmilled-unmixed samp
Institute of Electrical and Electronics Engineers
Type du document
Conférence : ASC2008 Applied Superconductivity Conference, Chigaco, IL, USA, 2008-08-17
ISSN : 1051-8223
IEEE transactions on applied superconductivity A. 2009, vol. 19, 3, pp. 2797-2801 [5 pages] [bibl. : 15 ref.]
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