Indium sesquiselenide, In₂Se₃

Indium sesquiselenide, In₂Se₃, is obtained by heating indium with selenium and repeatedly fusing the product with selenium. A brown precipitate of the same composition is produced by passing hydrogen selenide into indium acetate solution. The sesquiselenide is decomposed by dilute hydrochloric acid with the evolution of hydrogen selenide, and is eventually converted by nitric acid into indium selenite. When heated in hydrogen, hydrogen selenide and a dark sublimate (probably a lower selenide) are produced.