| abstract |
This invention provides a fluorescent substance as a fluorescent material for white LED using blue LED or ultraviolet LED as a light source. The fluorescent substance comprises a-type sialon represented by general formula: (M1)X(M2)Y(Si)12-(m+n)Al)m+n(O)n(N)16-n wherein M1 represents one or more elements selected from the group consisting of Li, Mg, Ca, Y, and lanthanide metals (excluding La and Ce); M2 represents one or more elements selected from Ce, Pr, Eu, Tb, Yb, and Er; and 0.3 ≤ X + Y ≤ 1.5, 0 < Y ≤ 0.7, 0.6 ≤ m ≤ 3.0, 0 ≤ n ≤ 1.5, and X + Y = m/2. The fluorescent substance is characterized in that the content of oxygen in the α-type sialon in a powder form is larger by not more than 0.4% by mass than a value obtained by calculation based on the above general formula. |