Nonagglomerated, submicron alpha-Fe2O3 particles: Preparation and application

Spherical particles of alpha-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 po wder material. The characteristic red color of hematite was adjusted after brief heating (250 degrees C, 15 min) which did not lead to further particl e 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 Y2O2S :Eu was coated as a model substrate. As a result, very homogeneous coatings of alpha-Fe2O3 on the phosphor material were realized. Individual iron oxi de particles on the phosphor surface confirm the presence of nonagglomerate d Fe2O3 particles in the polyol medium.