A mineral perovskite crystallizes in the cubic unit cell in which Ca 2+ and O 2– ions constitute a c — Inorganic Chemistry — Solid State Chemistry Question
Perovskite structure
A mineral perovskite crystallizes in the cubic unit cell in which Ca 2+ and O 2– ions constitute a ccp arrangement and Ti 4+ ion occupies an interstitial hole as shown here.
[VISUAL]
Based on the unit cell above, what is the empirical formula of perovskite?
Model Answer
Number of Ca 2+ ions: 8 corners × 1/8 ion Ca 2+/corner = 1
Number of O 2- ions: 6 cube faces × 1/2 O 2- ion/cube face = 3
Number of Ti 4+ ions: one Ti 4+ ion in the cube center = 1
Therefore, the empirical formula is CaTiO3.
Name types of interstitial holes present in the ccp unit cell. How many holes are there, for each type, within the unit cell?
Model Answer
(1) octahedral hole (4 per unit cell), (2) tetrahedral hole (8 per unit cell)
From your answer in 19.2, which type of interstitial hole is occupied by Ti 4+ ion?
Model Answer
Octahedral hole