Sialon-based oxynitride phosphor and production method thereof

A production method of an oxynitride phosphor comprising an α-sialon as the main component, comprising:

• (A) a first step of firing a mixed powder obtained by adding 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 a metal M (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) solid-dissolved in an α-sialon represented by the formula:
• MxSi12-(m+n)Al(m+n)OnN16-n:Lny
• (wherein 0.3≦x+y<1.5, 0<y<0.7, 0.3≦m<4.5, 0<n<2.25, and assuming that the atomic valence of the metal M is a and the atomic valence of the lanthanide metal Ln is b, m=ax+by), and
• (ii) a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of a lanthanide metal Ln (Ln is at least one lanthanide metal selected from the group consisting of Ce, Pr, Eu, Dy, Er, Tb and Yb) substituting a part or all of the metal element M to work as a luminescence center,
• to a silicon nitride powder, at 1,400 to 1,800° C. in a nitrogen-containing inert gas atmosphere to obtain a first raw material powder,
• (B) a second step of adding 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,
• to said first raw material powder, and weighing and mixing these to give an α-sialon composition represented by the formula:
• MxSi12-(m+n)Al(m+n)OnN16-n:Lny
• thereby obtaining a mixed powder, and
• (C) a third step of firing the obtained mixed powder at 1,500 to 2,000° C. in a nitrogen-containing inert gas atmosphere.