| 摘要 |
PURPOSE: To improve flux of light in the visible range and a maintenance factor of a light flux by setting the average grain size of an LiAlO2 : Fe phosphor at a specific percentage of the average grain size of a coexisting phosphor or more. CONSTITUTION: A lithium oxide or a compound which produces a lithium oxide on heating, and alumina or a compound which produces an aluminum oxide on heating are baked together with an activator to obtain an LiAlO2 : Fe phosphor. A grain size of the phosphor is controllable depending on the baking temperature, and for an average grain size of about 4μ, for example, a temperature of 1200 deg.C is appropriate. A phosphor for use in a normal fluorescent lamp is employed as the one which coexists with the LiAlO2 : Fe phosphor, and on amount of light emission in the visible range can be varied by varying the mixing ratio of the phosphors. Also, by setting the average grain size of the near-infrared light emitting LiAlO2 : Fe phosphor at 1/2 the average grain size of the coexisting phosphor or more, flux of light in the visible range and a maintenance factor of the light flux can be greatly improved.
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