| 摘要 |
A light emitting tube provided with a main phase, said main phase comprising polycrystalline alumina containing alumina crystals, and a first phase, said first phase being disposed at the crystal grain boundary of the alumina crystals and formed of a sintering aid containing lanthanum, wherein: the requirement S2/(S1+S2)×100≤0.5 [wherein S1 represents the total area of the main phase at the surface; and S2 represents the total area of the first phase at the surface] is satisfied; and the maximum equivalent circle grain diameter of the first phase is not greater than 4 μm. Thus, a light emitting tube, which has excellent mechanical strength and high linear transmittance and can be stably produced, and a discharge lamp are provided. |
