Corundum is the name for a structure prototype in inorganic solids, derived from the namesake
polymorph of
aluminum oxide (α-Al
2O
3).
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,
, polar
magnetism
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
,
and
magnetoelectric effects.
Structure
The corundum structure has the space group
. It typically exists in binary compounds of the type A
2B
3, where A is
metal
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
lic and B is
nonmetal
In chemistry, a nonmetal is a chemical element that generally lacks a predominance of metallic properties; they range from colorless gases (like hydrogen) to shiny solids (like carbon, as graphite). The electrons in nonmetals behave differentl ...
lic, including
sesquioxide
A sesquioxide is an oxide of an element (or radical), where the ratio between the number of atoms of that element and the number of atoms of oxygen is 2:3. For example, aluminium oxide and phosphorus(III) oxide are sesquioxides.
Many sesquioxid ...
s (A
2O
3),
sesquisulfide
Α sesquisufide is a compound that has the composition M2S3 where M is the element and S is sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmeta ...
s (A
2S
3), 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-Ca
3N
2 and
borates. Ternary and multinary compounds can also exists in the corundum structure. The corundum-like structure with the composition A
2BB'O
6 is called double corundum.
A list of examples are tabulated below.
See also
*
Corundum
Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the pres ...
*
Ilmenite
*
Perovskite (structure)
References
{{reflist
Crystal structure types
Crystallography
Mineralogy