We prepared bulk MgB2 from high-purity commercial powders of Mg metal (99.9% purity) and amorphous B (99% purity) powders using a single-step solid state reaction at 775°C for varying sintering duration from 1 to 10h in pure argon atmosphere. X-ray diffraction analysis showed that all the samples were single phase MgB2. The magnetization measurements confirmed a sharp superconducting transition with Tc,onset at around 38.2-38.8K. The critical current density (Jc) values for the MgB2 samples produced at 1h sintering time is the highest one in all processed materials here. Scanning electron microscopy analyses indicated that the sintering time has a crucial influence on the grain size. As a result, the highest Jc value of 270kAcm-2 at 20K and self-field was achieved in the sample produced at 775°C for 1h. Our results clearly demonstrate that the optimization of the sintering conditions is essential to improve the bulk MgB2 performance.
|ジャーナル||Physica Status Solidi (A) Applications and Materials Science|
|出版ステータス||Published - 2015 10 1|
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