Patent ID: 8628687

Claim:
A method of producing an oxynitride phosphor comprising an α-sialon represented by: M x Si 12−(m+n) Al (m+n) O n N 16−n :Ln y wherein 0.3≦x+y<1.5, 0<y<0.7, 0.3≦m<4.5, 0<n<2.25, and wherein the atomic valence of metal M is a and the atomic valence of lanthanide metal Ln is b, m=ax+by, as a main component, said method comprising: (A) firing a mixed powder at 1,400 to 1,800° C. in a nitrogen-containing inert gas atmosphere to obtain a first raw material powder, said mixed powder obtained by adding to a silicon nitride powder at least one kind of a metal compound selected from the group consisting of (i) a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of metal M, wherein M is at least one metal selected from the group consisting of Li, Ca, Mg, Ba, Sr, Y and a lanthanide metal excluding La, Ce, Pr, Eu, Dy, Er, Tb and Yb, and (ii) a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition of lanthanide metal Ln, wherein Ln is at least one lanthanide metal selected from the group consisting of Ce, Pr, Eu, Dy, Er, Tb and Yb, (B) adding to said first raw material powder at least one metal compound selected from the group consisting of: (i) a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of said metal M, (ii) a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of said lanthanide metal Ln substituting a part or all of said metal element M to work as a luminescence center, and (iii) an aluminum nitride powder, an aluminum oxynitride powder, an aluminum oxide powder or a precursor powder becoming aluminum oxide upon thermal decomposition, and weighing and mixing the compound and powder to produce said α-sialon composition thereby obtaining a mixed powder, and (C) firing the obtained mixed powder at 1,500 to 2,000° C. in a nitrogen-containing inert gas atmosphere.