Figure 3
(a) Schematic illustration of C-doped MgB2 bulk superconductor processed by infiltrating liquid Mg into Boron precursor containing 10% B4C at 850 °C. The illustrations shown from left to right represent the various stages of reaction with time. The xi value for 10% (B4C) is calculated to be 0.033. (b) Expected carbon concentration gradients originating from two different carbon sources. The relatively large difference in ΔC is due to a large variation in C at% between the two dissimilar SiC and B4C chemical phases. A higher degree of C variation within the Mg(B1-xiCxi)2 grain associated with (c) B4C addition relative to (d) SiC addition is observed. Carbon sources are represented by the dashed regions. Note that the intermediate boride formation during the transformation of B to Mg2B25 is not shown.
