Fabrication of highly dense MgB2 bulk at ambient pressure



Publication Details

Maeda, M, Zhao, Y, Dou, SX, Nakayama, Y, Kawakami, T, Kobayashi, H & Kubota, Y (2008), Fabrication of highly dense MgB2 bulk at ambient pressure, Superconductor Science and Technology, 21(3), pp. 032004-1-032004-4.


We report an in situ heat-treatment technique for the preparation of near-fully-dense un-doped MgB2bulks that also provides very strong in-field pinning. The high density was achieved without using high-pressure apparatus. The heat-treatment of compacted boron sealed in a Ta tube with Mg pellets employs a short high-temperature sintering at 1100°C first, followed by a low-temperature annealing below 660°C. A high density of 2.5 g cm-3 (95% of the theoretical density) was achieved in the bulks treated by the two-step process. The in-field Jc is nearly one order of magnitude higher than for the samples prepared by single-step sintering at high or low temperature. Microstructural analysis suggested a unique feature of well-connected small grains with a high level of disorder in the MgB2 samples created by the two-step process.

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