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Erschienen in:
22.12.2016
Enhancement of synthesis efficiency and critical current density in glycine-doped MgB2 bulks by two-step sintering
Erschienen in: Journal of Materials Science: Materials in Electronics | Ausgabe 7/2017
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Abstract
Glycine (Gly)-doped and Cu-and-Gly-co-doped MgB2 samples were two-step synthesized by a short 800 °C period followed by sintering at 600 °C for 2 h. In view of the depression of oxidation and the significant reduction of the synthesis time, the sintering efficiency was improved due to the instantaneous high-temperature process, in contrast with the one-step sintered samples at 800 °C. The critical current density was examined to be 5.1 × 103 and 8.4 × 103 A cm− 2 at 20 K and 3 T for the Gly-doped and the co-doped samples, respectively. Such enhancement, with respect to the one-step sintered un-doped sample, is attributed to the fine MgO (~20 nm) and Mg2Cu (~10 nm) pinning centers. The MgO and Mg2Cu in the co-doped sample precipitated at the grain boundary and within the grains, respectively. Besides, the residual Mg phase in the Gly-doped sample remained on the surface of the MgB2 grains, which proved the screw-dislocation growth of the MgB2 grains, i.e. the grains extended from inner center to outer zone at low temperature.