This paper reviews the crystal structure of compounds with the general form
ula AB(2)X(4), which crystallize with the same atomic structure as the mine
ral spinel, MgAl2O4. Three degrees of freedom associated with the detailed
atomic arrangements of spinels are considered here: (i) the lattice paramet
er, a; (ii) the anion parameter, a; and (iii) the cation inversion paramete
r, i. Oxide spinels are used as examples to explore the interrelationships
between these parameters.