Ferrous-Ferric Anomaly in Quadrupole Moment ofFe57m

The nuclear quadrupole moment $Q$ of ${\mathrm{Fe}}^{57m}$ has been determined from the calculated electric field gradients (including all the metal-ion-ligand overlaps) and the quadrupole splitting data in ${\mathrm{Fe}}_2$ ${\mathrm{O}}_3$ and ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$:${\mathrm{Fe}}^{3+}$. The values of $Q\left({\mathrm{Fe}}^{57m}\right)$ obtained in the two cases are 0.180 ± 0.015 and 0.204 ± 0.018 b which are consistent with the values reported in ferrous compounds, thus disposing of the well-known ferrous-ferric anomaly.