Patent ID: 7736535

Claim:
A phosphor represented by formula (M 1 1-a Ln 2 a ) 2 (M 2 1-b Ln 1 b ) 2 M 3 2 O 9 wherein M 1 is at least one metal element selected from the group consisting of Ca, Sr, and Ba, M 2 is at least one metal element selected from the group consisting of Y, La, Gd, and Lu, M 3 is at least one metal element selected from the group consisting of Si and Ge and oxygen, Ln 1 is at least one metal element selected from the group consisting of Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Mn, Ln 2 is at least one element selected from the group consisting of Sm, Eu, Yb, and Mn, a is from 0 to 0.5, b is from 0 to 0.5, and the sum of a and b is not less than 0.