Fig. 3
From: Progress in Iron Oxides Based Nanostructures for Applications in Energy Storage
Reprinted with Permission from [42]. Copyright, Elsevier Masson SAS
Comparison of 57Fe Mössbauer spectra at 300 K of the pristine Fe1−xO material (a), after an uptake of 1 Li (b) and the end for discharge at 2.16 Li (c). Green contributions are attributed to FeII. The thicker green line is sum of the thinner one corresponding to unreacted Fe1−xO. Dashed blue line corresponds to the expected increasing contribution of α-Fe from (a) to (c). In the case of (c), magnetic sextet has been slightly shifted as a guide of the eye. Spectrum (d) corresponds to the end of the first charge at 0.94 Li with no α-Fe contribution, but the blue singlet nanosized metallic ε-Fe0 is still present.