N 1647 (OTTO) Niobium pentoxide, 99.9% Cas 1313-96-8 - used mainly in the production of niobium metal, but specialized applications exist for lithium niobate and as a component of optical glass. N 1647 (OTTO) Niobium pentoxide, 99.9% Cas 1313-96-8 - used in glass, optic and ceramic applications.