Antimony tetroxide is an inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula Sb₂O₄. This material, which exists as the mineral cervantite, is white but reversibly yellows upon heating. The material, with empirical formula SbO₂, is called antimony tetroxide to signify the presence of two kinds of Sb centers.

Formation and structure

The material forms when Sb₂O₃

Antimony trioxide

Antimony trioxide is the inorganic compound with the formula Sb2O3. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite...

 is heated in air:

Sb₂O₃ + 0.5 O₂ → Sb₂O₄ ΔH = −187 kJ/mol

At 800 °C, antimony(V) oxide

Antimony pentoxide

Antimony pentoxide is a chemical compound of antimony and oxygen. It always occurs in hydrated form, Sb2O5·nH2O. It contains antimony in the +5 oxidation state.-Structure:...

 loses oxygen to give the same material:

Sb₂O₅ → Sb₂O₄ + 0.5 O₂ ΔH = −64 kJ/mol

The material is mixed valence, containing both Sb(V) and Sb(III) centers. Two polymorphs

Polymorphism (materials science)

Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...

are known, one orthorhombic (shown in the infobox) and one monoclinic. Both forms feature octahedral Sb(V) centers arranged in sheets with distorted Sb(III) centers bound to four oxides.