Oxybismuthides

Oxybismuthides or bismuthide oxides are chemical compounds formally containing the group BiO, with one bismuth and one oxygen atom. The bismuth and oxygen are not bound together as in bismuthates, instead they make a separate presence bound to the cations (metals), and could be considered as a mixed bismuthide-oxide compound. So a compound with O_mBi_n requires cations to balance a negative charge of 2m+3n. The cations will have charges of +2 or +3. The trications are often rare earth elements or actinides. They are in the category of oxypnictide compounds.

Many of the bismuthide oxides have bismuth in an unusual -2 oxidation state. The ones with Ln₂BiO₂ have the anti-ThCr₂Si₂ structure. They include alternating layers of LnO (anti-fluorite-type) and LnBiO. The Eu₄Bi₂O has an anti-K₂NiF₄ structure, the same as for Na₂Ti₂As₂O. Some other compounds contain calcium and a rare earth CaRE₃BiO₄, and Ca₂RE₈Bi₃O₁₀.^[1]

Some of these compounds are superconductors at very low temperatures and many are semiconductors at standard conditions.^[1]

^ ^a ^b Forbes, Scott; Mozharivskyj, Yurij (2017-11-28). "Rare-Earth Pnictide Oxides ( RE ,Ca) m Pn n O m ( Pn = Sb, Bi): A Review of Crystal Structures, Chemistry, Compositions, and Physical Properties". Chemistry of Materials. 29 (22): 9605–9612. doi:10.1021/acs.chemmater.7b03996. ISSN 0897-4756.

[:3-1] Forbes, Scott; Mozharivskyj, Yurij (2017-11-28). "Rare-Earth Pnictide Oxides ( RE ,Ca) m Pn n O m ( Pn = Sb, Bi): A Review of Crystal Structures, Chemistry, Compositions, and Physical Properties". Chemistry of Materials. 29 (22): 9605–9612. doi:10.1021/acs.chemmater.7b03996. ISSN 0897-4756.

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