Aluminium antimonide (AlSb) is a semiconductor of the group III-V family containing aluminium and antimony. The lattice constant is 0.61 nm. The indirect bandgap is approximately 1.6 eV at 300 K, whereas the direct band gap is 2.22 eV. Its electron mobility is 200 cm2·V−1·s−1 and hole mobility 400 cm2·V−1·s−1 at 300 K. Its refractive index is 3.3 at a wavelength of 2 μm, and its dielectric constant is 10.9 at microwave frequencies. AlSb can be reacted with other III-V materials to produce ternary materials including AlInSb, AlGaSb and AlAsSb. Aluminium antimonide is rather flammable because of the reducing tendency of the antimonide (Sb3−) ion. It burns to produce aluminium oxide and antimony trioxide.