Figure 4. Disordering transformations in spinel.

Schematic showing the structure of spinel and the structural modifications that occur when ordered spinel is transformed to disordered spinel and to disordered rocksalt, as described by equations 2 and 1, respectively. Although the first involves simply swapping cations, the second transformation requires a movement of cations from tetrahedral sites (highlighted by the yellow tetrahedra) to empty octahedral sites. Blue spheres represent oxygen while yellow spheres are Mg and red spheres are B cations. The mixed spheres indicate sites with mixed (random) populations. Figure inspired by ref. 66.