Oxides and Sulfides
Niobium forms oxides with the oxidation states +5 (Nb2O5), +4 (NbO2), and +3 (Nb2O3), as well as with the rarer oxidation state +2 (NbO). Most commonly encountered is the pentoxide, precursor to almost all niobium compounds and alloys. Niobates are generated by dissolving the pentoxide in basic hydroxide solutions or by melting it in alkali metal oxides. Examples are lithium niobate (LiNbO3) and lanthanum niobate (LaNbO4). In the lithium niobate is a trigonally distorted perovskite-like structure, whereas the lanthanum niobate contains lone NbO43− ions. The layered niobium sulfide (NbS2) is also known.
Materials with a thin film coating of niobium(V) oxide can be produced by chemical vapor deposition or atomic layer deposition processes, in each case by the thermal decomposition of niobium(V) ethoxide above 350 °C.