Question

Ilmenite (VITiVIFeO3) has an HCP stacking of oxygen layers. What fraction of the possible octahedral and tetrahedral sites is filled by Ti and Fe?

Answer 1

Here is the detailed answer for your question....

• 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.

• This structure is very similar to Corundum or α - Al₂O₃.

• 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

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• Coordination numbers: both Fe and Ti remain octahedrally coordinated while O is coordinated by 4 cations i.e. 2 Fe and 2 Ti.

• HOpe this helped.Thank you.