A reactivity study in the Mg–B system reaching for an improved synthesis of pure MgB2

The binary Mg–B system was studied with respect to the existing phases MgB2, MgB4, MgB7, and MgB12 and their transformations into each other. As a result of these studies, a new synthesis route is reported for MgB2 by reacting MgB4 and Mg with each other. The obtained MgB2 was characterized by Rietveld refinement of the powder XRD pattern (RBragg = 3.56%, Rwp = 10.6%), magnetic measurements, and by electron probe microanalysis (EPMA). With this new synthesis route, a better phase homogeneity is obtained when compared with MgB2 samples prepared from the elements.