The stoichiomteric formula is ABO3 (different to perovskite ABO3)
The parent compound is FeTiO3.
Other compounds which follow this structure are CdTiO3, CoTiO3, CrRhO3, FeRhO3, FeVO3, LiNbO3, MgGeO3, MgTiO3.
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This structure is very similar to Corundum or α - Al2O3.
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Imagine the Corundum structure and replace Al atoms in the octahedral sites in one (0001)‑layer i.e. half of the total aluminum atoms by Fe and the remaining half in the next layer by Ti atoms in the octahedral sites and continue this order of substitution along the c-axis of the unit-cell.
Hence, the atomic arrangement is similar to Al2O3 except with alternate layers of Fe and Ti in place of Al
.Coordination numbers: both Fe and Ti remain octahedrally coordinated while O is coordinated by 4 cations i.e. 2 Fe and 2 Ti.
Bond strength rule gives correct oxygen valence:
Figure 1.42 Layered filling of Ilmenite |
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One unit-cell consists of six layers of oxygen ions.
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A side view of the structure on {10-10} plane, as shown below, shows the columns of cations along the c-axis with
2⁄3rd filling of octahedral sites which are alternately filled by Fe and Ti ions and then followed by a vacant site.
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