Nonagglomerated, submicron α–Fe₂O₃ particles: Preparation and application

Spherical particles of α–Fe₂O₃ 80 to 100 nm in size were prepared with the polyol method. Scanning electron microscopy, x-ray powder diffraction, and measurements of the diffuse reflection were used to characterize the powder material. The characteristic red color of hematite was adjusted after brief heating (250 °C, 15 min) which did not lead to further particle growth. The polyol method turned out to be suited for the preparation of quite concentrated (up to 20 wt%) and very stable suspensions of submicron Fe₂O₃ particles. Based on such suspensions, the red emitting phosphor Y_{2_{O₂S:Eu was coated as a model substrate. As a result, very homogeneous coatings of α-Fe₂O₃ on the phosphor material were realized. Individual iron oxide particles on the phosphor surface confirm the presence of nonagglomerated Fe₂O}3} particles in the polyol medium.