Phase Equilibria in the System La ₂ O ₃ —Iron Oxide in Air

Abstract

Phase equilibria data are presented for compositions in the system La 2 O 3 ‐iron oxide in air. Liquidus and solidus curves were obtained by the quenching method in the iron‐rich portion of the system. The remainder of the diagram was determined using a strip‐furnace technique. Two compounds have been found, the ortho‐rhombic perovskite LaFeO 3 and a compound with the magnetoplumbite structure corresponding to a composition LaFe 12 O 19 . LaFeO 3 was determined to melt congruently at about 1890°C. whereas LaFe 12 O 19 has both a stability minimum and maximum at 1380° and 1421°C., respectively. The iron‐rich portion of the system is essentially ternary whereas the remainder can be considered to be a simple binary. Liquid compositions have been determined and are plotted in terms of the ternary system La 2 O 3 ‐Fe 2 O 3 ‐FeO.