Glycothermal Reaction of Rare‐Earth Acetate and Iron Acetylacetonate: Formation of Hexagonal ReFeO3

The reaction of a mixture of iron acetylacetonate and rare-earth (Tm-Lu) acetate in 1,4-butanediol at 300°C yielded a novel phase of ReFeO3 having a hexagonal crystal system (a0 = 6.06, c0= 11.74 A) together with small amounts of Fe3O4and/or the garnet phase. The particle size of the product distributed in a narrow range and selected area electron diffraction from a particle having apparent polycrystalline outlines suggested that each particle was actually a single crystal grown from one nucleus. On calcination, the hexagonal phase irreversibly transformed into the perovskite phase at around 980°C. The use of ethylene glycol in place of 1,4-butanediol of the present procedure afforded Fe3O4, while hydrothermal reaction of the same starting materials yielded a mixture of Fe2O3and an amorphous rare-earth phase.