Vanadium(III) oxide is the inorganic compound with the formula V
2O
3. It is a black solid prepared by reduction of vanadium pentoxide, V
2O
5 with hydrogen or carbon monoxide.
It is a basic oxide dissolving in acids to give solutions of vanadium (III) complexes.
V
2O
3 has the corundum structure.
It is antiferromagnetic with a critical temperature of 160 K.
[E.M. Page, S.A.Wass (1994),''Vanadium:Inorganic and Coordination chemistry'', Encyclopedia of Inorganic Chemistry, John Wiley & Sons, ] At this temperature there is an abrupt change in conductivity from metallic to insulating.
This also distorts the crystal structure to a monoclinic space group: C2/c.
Upon exposure to air it gradually converts into indigo-blue vanadium dioxide, V
2O
4.
In nature it occurs as the rare mineral karelianite.
References
Vanadium(III) compounds
Sesquioxides
Hematite group
{{Inorganic-compound-stub
Transition metal oxides