592464.fig.006
Figure 6: Raman spectra of the (a) (Fe3O4)1(MgO)9, (b) (Fe3O4)1.75(MgO)8.25, (c) (Fe3O4)2.5(MgO)7.5, and (d) (Fe3O4)3.25(MgO)6.75 catalysts after reaction.