Synthesis of Mg(B1−xCx)2 powders

We have synthesized bulk Mg(B1−xCx)2 from a mixture of elemental Mg, B, and the binary compound B4C. Carbon incorporation was dramatically improved by a two step reaction process at an elevated temperature of 1200 °C. This reaction process results in a solubility limit near x ∼ 0.07. We found that impurities in the starting B cause an additive suppression of Tc. We combine these data with Tc and Hc2(T = 0) data from CVD wires as well as plasma spray synthesized powders and present a unifying Hc2 and Tc versus x plot.