Table 2: Fitting parameters for Figure 4.

Dopant Vanadium (in non-porous SiC) 0.32 0.23 0.21 0.33 Vanadium (in porous SiC) 0.29 0.24 0.23 0.21 Erbium (in non-porous SiC) 0.31 0.24 0.10 0.27 Erbium (in porous SiC) 0.33 0.30 0.22 0.19