Spinellstructured

Spinellstructured refers to a specific crystal structure adopted by compounds with the general chemical formula AB2O4, where 'A' represents a divalent cation and 'B' represents a trivalent cation. This structure is named after the mineral spinel, which has the composition MgAl2O4. The defining characteristic of the spinel structure is its arrangement of ions within a cubic lattice. Oxygen ions form a face-centered cubic (FCC) packing. Within the interstitial sites of this oxygen lattice, the cations A and B occupy specific positions.

There are two types of interstitial sites available: tetrahedral sites, which are coordinated by four oxygen ions, and octahedral sites, which are coordinated by six oxygen ions. In the normal spinel structure, the divalent A cations preferentially occupy half of the tetrahedral sites, while the trivalent B cations occupy half of the octahedral sites. However, in an inverse spinel structure, the divalent A cations occupy half of the octahedral sites, and the trivalent B cations are distributed such that half occupy the tetrahedral sites and the other half occupy the remaining octahedral sites. A mixed spinel structure is also possible, where the distribution of cations is somewhere between the normal and inverse configurations.

The spinel structure is a common motif found in a wide variety of inorganic compounds, including many oxides, sulfides, and even some halides. These materials exhibit a broad range of physical and chemical properties, making them important in applications such as ceramics, catalysts, magnetic materials, and solid oxide fuel cells. The precise arrangement of cations (normal, inverse, or mixed) significantly influences these properties.