Barium Suboxide, Ba₂O

By heating barium oxide with metallic magnesium to 900°-1100° C., a blackish sintered residue, which reacts with water, producing hydrogen equivalent to half the barium employed, is obtained. A similar product is formed by heating together metallic barium and barium oxide. Guntz regarded it as the Barium Suboxide, Ba₂O. It absorbs nitrogen and hydrogen at red heat. With hydrogen the reaction is

Ba₂O + H₂ = BaH₂ + BaO.

The mixture of barium hydride and oxide behaves as if it were the compound BaH.

Barium suboxide dissociates into barium and barium oxide when strongly heated. If a volatile metal be used for the reduction, the dissociated barium volatilises with the excess of the reducing metal, forming an alloy. The temperature must be higher than that necessary to volatilise barium, in order to dissociate the suboxide. If a nonvolatile metal, such as aluminium, be used, the suboxide is still the first product, but this splits up into barium oxide and barium, the latter distils off alone, and the remaining oxide is again reduced to the suboxide.