Niobium oxide, archaically called columbium oxide, may refer to:
Niobium monoxide (niobium(II) oxide), NbO Niobium dioxide (niobium(IV) oxide), NbO2 Niobium pentoxide (niobium(V) oxide), Nb2O5
In addition to the above, other distinct oxides exist general formula Nb3n+1O8n−2 where n ranges from 5 - 8 inclusive, e.g. Nb8O19 (Nb16O38). Nb12O29 and Nb47O116
Natural niobium oxide is sometimes known as niobia.
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