Oxide Ceramic Fluorescent Material Having Rare Earth Diffused Therein

摘要

An oxide ceramic fluorescent material is provided comprising a polycrystalline ceramic sintered body of Y 3 Al 5 O 12 , Lu 3 Al 5 O 12 , (Y,Lu) 3 Al 5 O 12 , (Y,Gd) 3 Al 5 O 12 , or Al 2 O 3 in which a rare earth element selected from Ce, Eu and Tb has been diffused from its surface as fluorescent activator. The concentration of the rare earth element is 1 wt% at a depth of 50-600 µm as measured from the sintered body surface and at least 1 wt% at any position nearer to the sintered body surface.