The combined influence of connectivity and disorder on Jc and Tc performances in MgxB2+10 wt % SiC

The influences of connectivity and disorder on the critical current density Jc are discussed to clarify the different mechanisms of Jc(H) enhancement in different magnetic field ranges. Excess Mg in MgxB2+10 wt % SiC composites effectively improves the connectivity, as evidenced by both the resistivity properties and the Raman scattering. The promising Jc(H) of Mg1.15B2+10 wt % SiC is attributed to both the high connectivity and the improved irreversibility field, Hirr, which is in agreement with the Raman fitting analysis. Raman scattering measurements suggest a strengthened electron-E2g coupling and weakened disorder with Mg addition.