A combined process of a mechanical ball milling and liquid glycerin (C 3 H 8 O 3 ) treatment of boron (B) powder has been conducted to enhance the superconducting properties of MgB 2 . The individual aims of the mechanical milling and the glycerin treatment were to reduce the grain size of the MgB 2 and to achieve homogeneous carbon (C) incorporation into the MgB 2 , respectively. Four kinds of B powders of as-received, glycerin treated, 2 h milled and 2 h milled + glycerin treated were prepared. MgB 2 bulks were fabricated by an in situ process using the prepared B powders. According to our experimental results, the mechanical ball milling was effective for grain refinement, and a lattice disorder was easily achieved by glycerin addition. It was found that the critical current density (J c ) values were enhanced in the samples with milled B or glycerin-treated B only. In the MgB 2 bulk prepared with both milled and glycerin-treated B, the J c was further increased to 1.27 × 10 4 A cm −2 at 5 K and 8 T due to a higher grain boundary density and a greater C substitution. The upper critical field and irreversibility field were also further enhanced by a combined treatment process of the B powder.
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