How many aluminium ions are present per unit cell of corundum (Al2O3) - Chemistry - The Solid State

Question

How many aluminium ions are present per unit cell of corundum
(Al2O3)?

veena Vasandani · Accepted Answer

Corundum crystallises with trigonal
symmetry and each unit cell contains 6 formula units
each formula unit has 2 Al3+ ions Hence, each
unit cell has 12 Al3+ ions

How many aluminium ions are present per unit cell of corundum (Al2O3)?