Bulk MgB2 materials were synthesized electrochemically from fused mixtures of MgCl2, NaCl, KCl and MgB2O4 under an Ar flow at 600C . Electrical resistivity measurements for the samples exhibited an onset of superconducting transition at ~37K in the absence of an applied magnetic field. This temperature was quite close to that observed from magnetic measurements. The resistivity decreased to zero below ~32K. From the applied-field dependence of resistivity, the upper critical field and the coherence length were calculated to be 9.7T and 5.9nm, respectively, at 0K.

Electrical Transport Properties of Bulk MgB2 Materials Synthesized by Electrolysis on Fused Mixtures of MgCl2, NaCl, KCl and MgB2O4. K.Yoshii, H.Abe: Superconductor Science and Technology, 2002, 15, L25-7