Corundum (structure)
Corundum is the name for a structure prototype in inorganic solids, derived from the namesake polymorph of aluminum oxide. Other compounds, especially among the inorganic solids, exist in corundum structure, either in ambient or other conditions. Corundum structures are associated with metal-insulator transition, ferroelectricity, polar magnetism, and magnetoelectric effects.
Structure
The corundum structure has the space group [hexagonal crystal family|]. It typically exists in binary compounds of the type A2B3, where A is metallic and B is nonmetallic, including sesquioxides, sesquisulfides, etc. When A is nonmetallic and B is metallic, the structure becomes the antiphase of corundum, called the anticorundum structure type, with examples including β-Ca3N2 and borates. Ternary and multinary compounds can also exists in the corundum structure. The corundum-like structure with the composition A2BB'O6 is called double corundum. A list of examples are tabulated below.| Chemical formula | Alternative name | Material type | Reference |
| Al2O3 | α-Al2O3 or corundum | Oxide | |
| V2O3 | Oxide | ||
| Cr2O3 | α-Cr2O3 | Oxide | |
| Fe2O3 | α-Fe2O3 or hematite | Oxide | |
| Ga2O3 | α-Ga2O3 | Oxide | |
| In2O3 | rh-In2O3 | Oxide | |
| Ti2O3 | α-Ti2O3 | Oxide | |
| Mn2O3 | ε-Mn2O3 | Oxide | |
| Rh2O3 | Oxide | ||
| Ir2O3 | α-Ir2O3 | Oxide | |
| Tl2O3 | Oxide | ||
| Ca3N2 | β-Ca3N2 | Nitride | |
| In2S3 | ε-In2S3 | Sulfide | |
| Tm2S3 | E-Tm2S3 or ε-Tm2S3 | Sulfide | |
| Yb2S3 | E-Yb2S3 or ε-Yb2S3 | Sulfide | |
| Lu2S3 | E-Lu2S3 or ε-Lu2S3 | Sulfide | |
| Cr23 | Carbodiimide | ||
| Yb23 | Carbodiimide | ||
| Ca32 | Borate | ||
| Sr32 | Borate | ||
| Eu32 | Borate | ||
| ScFeO3 | Ferrite | ||
| GaFeO3 | Ferrite | ||
| InFeO3 | Ferrite | ||
| CrTiO3 | Titanate | ||
| NiCrO3 | Chromite | ||
| InVO3 | Vanadate | ||
| Ni3TeO6 | Double oxide | ||
| Ni2InSbO6 | Double oxide | ||
| Ni2ScSbO6 | Double oxide | ||
| Mn2FeMoO6 | Double oxide | ||
| Mn2FeWO6 | Double oxide | ||
| Co4Ta2O9 | Triple oxide |