Fe‐Nb Oxides: Phase Relations at 1180°C

Subsolidus phase relations of the oxides in the system Fe–Nb–O were experimentally determined at 1180°C, 1 atm total pressure, and variable partial pressures of oxygen. Niobium pentoxide reacts readily with either ferrous or ferric oxide at subsolidus temperatures and the following ternary compounds were synthesized: Fe 4 Nb 2 O 9 , FeNbO 4 , and FeNb 2 O 6 . It is shown that the rutile structure of NbO 2 will take Fe‐Nb 2 O 6 into solid solution and that the spinel structure of Fe 3 O 4 will incorporate up to 7 at.% Nb.