The present study discovers the significant enhancement of critical current density by the pinning of borohydride and crystal defects in the hydrogen-treated MgB2 bulks. Based on the concept of gas doping, the nanosized borohydride Mg(BH4)2 is formed by synthesizing H-doped MgB2 bulks in an H2 atmosphere at 300 °C and 350 °C, and the critical current density was enhanced over the entire field. The H-doped MgB2 bulks are then experienced dehydrogenation at 300 °C and 350 °C, respectively, and the decomposition of Mg(BH4)2 induced nanosized pits on the surface of the MgB2 grains, leading to a further enhancement of critical current density, 1.5 × 104 A cm−2 at 20 K and 2.5 T, which is three times larger than that of the un-doped MgB2 sample, 4.8 × 103 A cm−2. The hydrogenation and dehydrogenation hardly changed the superconducting transition temperature or the pinning mechanism of the MgB2 samples. The enhancement of the critical current density is possibly attributed to the pinning effects of the crystal defects, and the reduction of MgO.
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This work was supported by the National Natural Science Foundation of China (Grant No. 51804195).
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Cai, Q., Li, X., Li, S. et al. Dehydrogenation-induced crystal defects for significant enhancement of critical current density in polycrystalline H-doped MgB2. J Mater Sci: Mater Electron (2020). https://doi.org/10.1007/s10854-020-04862-x