Antifluorite Structure ( Na2O )
position of anion :- O2- forms FCC unit cell
position of cation :- Na+ occupy al tetrahedral void
Coordination no :- 4:8 ( Co No of Na+ = 4, Co No of O2- = 8)
No of ions per unit cell :- 8 Na+ n 4 O2-
Formula of unit cell :-Na2O
(4 molecules of Na2O per unit cell )
Spinel Structure ( AB2O4 )
[ eg: MgAl2O4]
position of anion :- O2- forms FCC
position of cation :- A2+ occupy 1/8 of tetrahedral void (i.e. 1A2+ )
B3+ occupy 1/2 of octahedral void (i.e. 2B3+ )
Inverse Spinel Structure ( Fe3O4)
position of anion :- O2- forms FCC unit cell
position of cation :- Fe3+ occupy 1/8 of tetrahedral void (i.e. 1Fe3+ )
Fe2+ occupy 1/4 of octahedral void (i.e. 1 Fe2+ )
Fe3+ occupy 1/4 of octahedral void (i.e. 1Fe3+ )
Formula Ratio : Fe2+ : Fe3+ : O2- = 1 :2 : 4
Pervoskite Structure ( CaTiO3 )
Ca2+ forms primitive unit cell ( 1 Ca2+ )
O2+ occupies face centers ( 3 O2+ )
Ti4+ located at body center ( 1Ti4+ )
Formula Ratio : Ca Ti O3 = 1 :1 : 3
Moderation Team
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