Patent ID: 7074346

Claim:
An Î±-sialon-based oxynitride phosphor powder characterized in that the content of Î±-sialon represented by the general formula: M x Si 12âˆ’(m+n) Al (m+n) O n N 16âˆ’n :Ln y (wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, 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, 0.3â‰¦x+y<1.5, 0<y<0.7, 0.3â‰¦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, wherein all or a portion of the metal M dissolved in the Î±-sialon is replaced with the lanthanide metal Ln as the luminescence center), is 75 wt % or greater as measured by powder X-ray diffraction when the lanthanide metal Ln is at least one lanthanide metal selected from among Ce, Pr and La or 90 wt % or greater as measured by powder X-ray diffraction when the lanthanide metal Ln is at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb, with the remainder consisting of Î²-sialon and oxynitride glass and in that the content of metal impurities other than the metal M, lanthanide metal Ln, silicon, IIIA elements (aluminum, gallium), oxygen and nitrogen, is no greater than 0.01 wt %.