Barium suboxides

The structural principle of combining salt-like bonded units with stoichiometric amounts of alkali metal in the structure of Ba2ONa is equivalent to that which characterizes the alkali metal suboxides as well as the subnitrides of alkaline earth metals, such that a variation at least according to a general formula [Ba20 Na% can be expected. Indeed, there are indications of the existence of further suboxides in 

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Boutou V, Lebeault M A, Allouohe A R, Bordas C, Paulig F, Viallon J and Chevaleyre J 1998 Struotural transition in barium suboxide olusters Phys. Rev. Lett. 80 2817... 

The alkali metal suboxides are well understood in terms of formation, structure, and properties, yet we still face some unsolved problems that will also be addressed in the following. In contrast, the first suboxide of barium came to light only recently [24], and one has to see whether this compound is the tip of another iceberg, as turned out to be the case with the subnitrides of alkaline earth metals. 

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