A New Synthetic Route to

Wüstite with NaCl structure is successfully synthesized in a quartz tube sealed under vacuum ( − ∼ 1×10–3 torr). Hematite in an evacuated quartz tube progressively loses oxide ion at 1373 K. XRD patterns disclose that α-Fe2O3 is transformed into the Fe3O4 after heat treatment at 1373 K for 32 h, and the poorly crystallized FeO is appeared after heat treatment for 48 h. Finally, α-Fe2O3 is completely transformed into the well crystallized Fe0.935O after heat treatment for 84 h. The electrical resistivity, ac-susceptibility measurement, Mössbauer spec-troscopy, and x-ray absorption spectroscopy corroborate the structural phase transition on the iron oxides pre-pared in a sealed quartz tube depending on the heating time at 1373 K