Bulk Mg(B1−xCx)2 was synthesized from a mixture of elemental Mg, B and B4C. The C incorporation was dramatically improved by using a 2-step reaction process at 1200C . This reaction process results in a solubility limit near to x = 0.07. It was found that impurities in the starting B cause an additive suppression of TC. These data were combine with TC and HC2(T = 0) data from CVD wires as well as plasma spray synthesized powders and presented a unifying HC2 and TC versus x plot.

Synthesis of Mg(B1−xCx)2 Powders. R.H.T.Wilke, S.L.Budko, P.C.Canfield, D.K.Finnemore, S.T.Hannahs: Physica C, 2005, 432[3-4], 193-205