EUROPIUM-ACTIVATED YTTRIUM OXIDE AND PROCESS FOR PRODUCING THE SAME

摘要

This invention provides a europium-activated yttrium oxide which has a median diameter of 2 to 8 µm as measured by a laser diffraction/scattering method and a (d2?)cos? of 0.083 degree at the largest as calculated from a diffraction peak from a 440 face measured by an X-ray diffraction method wherein ? represents a diffraction angle; and d2? represents a half value width (degree) of a diffraction peak. This europium-activated yttrium oxide may be produced by mixing a europium-containing yttrium compound and a flux together in a water system to prepare a slurry, spray drying the slurry to prepare spherical secondary particles, and then firing the secondary particles so that the median diameter after the firing is 0.65 to 0.75 time that of the median diameter before the firing to bring the median diameter after the firing to 2 to 8 µm. The europium-activated yttrium oxide is a red fluorescent substance suitable for electron beam excitation light emitting elements, for example, in electric field emission displays (FEDs).