Fe-Mg-Si ternary diagram (at%) showing the composition field of the sol-gel samples, E10 (top left panel), E20 (top right panel), E30 (bottom left panel) and E40 (bottom right panel). Each red point represents an individual analysis with a selected volume of matter of ~10^-3μm³. The blue point is the target composition. The slight offset between the target composition and the sol-gel sample is likely due to a small Mg loss under the beam during the analyses.