Question

Perovskite is a mineral with the formula $CaTi{O}_3$. Which of the positive ions in the crystal is more likely to be packed in the octahedral holes?

• A. $T{i}^{4+}$
• B. $T{i}^{2+}$
• C. $C{a}^{2+}$
• D. $O_2^{+}$

Answer 1

Answer: (A)

$T{i}^{4+}$

In perovskite crystals, smallest cation will be present at octahedral void present at body centre.

$⟶$ $C{a}^{+2}>>T{i}^{+4}$

Therefore, $T{i}^{+4}$ will be present at octahedral void at body centre.

Also, $C{a}^{+2}$ will be present at body corners

$O^{2-}$ will be present at face centres.

$\Rightarrow {Z_{Ca}}^{+2}=8\times \frac{1}{8}=1$ ${Z_a}^{2-}=6\times \frac{1}{2}=3$ ${Z_{Ti}}^{+4}=1$

$CaTi{O}_3$