Sialon-based oxynitride phosphor, process for its production, and use thereof

A process for producing an α-sialon-based oxynitride phosphor powder, wherein a mixed powder comprising a) a nitrogen-containing silane compound and/or amorphous silicon nitride powder having the oxygen content adjusted to 1–5 wt %, b) AlN and/or Al powder, c) an oxide of a metal M or a precursor substance which is converted to an oxide of a metal M upon thermal decomposition, and d) an oxide of a lanthanide metal Ln or a precursor substance which is converted to an oxide of a lanthanide metal Ln upon thermal decomposition, in a combination such that the metal impurity content is no greater than 0.01wt % as calculated on the basis of the product being represented by the general formula:

• MxSi12−(m+n)Al(m+n)OnN16−n:Lny
• (wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, and
• Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,
• 0.3≦x+y<1.5,
• 0<y<0.7,
• 0.3≦m<4.5,
• 0<n<2.25, and
• m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln), is fired at 1400–2000° C. in a nitrogen gas atmosphere or nitrogen-containing inert gas atmosphere.

A process for producing an α-sialon-based oxynitride phosphor powder, wherein a mixture obtained by adding a pre-synthesized α-sialon powder represented by the general formula:

• MxSi12−(m+n)Al(m+n)OnN16−n(wherein the definitions in the formula are the same as below) or the general formula:
• MxSi12−(m+n)Al(m+n)OnN16−n:Lny (wherein the definitions of M, Ln, x, y, m and n are the same as below) to a mixed powder comprising a) a nitrogen-containing silane compound and/or amorphous silicon nitride powder having the oxygen content adjusted to 1–5 wt %, b) AlN and/or Al powder, c) an oxide of a metal M or a precursor substance which is converted to an oxide of a metal M upon thermal decomposition, and d) an oxide of a lanthanide metal Ln or a precursor substance which is converted to an oxide of a lanthanide metal Ln upon thermal decomposition, in a combination such that the metal impurity content is no greater than 0.01 wt % as calculated on the basis of the product being represented by the general formula:
• MxSi12−(m+n)Al(m+n)OnN16−n:Lny
• (wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, and
• Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,
• 0.3≦x+y<1.5,
• 0<y<0.7,
• 0.3≦m<4.5,
• 0<n<2.25, and
• m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln), is fired at 1400–2000° C. in a nitrogen gas atmosphere or nitrogen-containing inert gas atmosphere.