Formation of MgB₂ at low temperatures by reaction of Mg with B₆Si

Formation of MgB₂ by reactions of Mg with B₆Si and Mg with B were compared, the former also producing Mg₂Si as a major product. Compared to the binary system, the ternary reactions for identical time and temperature were more complete at 750°C and below, as indicated by higher diamagnetic shielding and larger x-ray diffraction peak intensities relative to those of Mg. MgB₂ could be produced at temperatures as low as 450°C by the ternary reaction. Analyses by electron microscopy, x-ray diffraction and of the upper critical field show that Si does not enter the MgB₂ phase.