The mineral haematite, Fe_2O_3 consists of a cubic close packed array of oxide ions with Fe^(3+) ions occupying interstitial positions. Predict whether the iron ions are in the octahedral or tetrahedral holes. Radius of Fe^(3+)=0.65 Å and that of O^(2-)=1.45 Å

The mineral haematite, Fe_2O_3 consists of a cubic close packed array

1.	The mineral haematite, Fe_2O_3 consists of a cubic close packed array of oxide ions with Fe^(3+) ions occupying interstitial positions. Predict whether the iron ions are in the octahedral or tetrahedral holes. Radius of Fe^(3+)=0.65 Å and that of O^(2-)=1.45 Å
Answer» Solution :`r_+ //r_` =0.65 Å/ 1.45 Å which lies in the range 0.414-0.732 . Hence , `FE^(3+)` IONS will be in the OCTAHEDRAL HOLES.