Patent ID: 7825580

Claim:
A phosphor comprising: α-type sialon crystal as a main component, wherein the α-type sialon crystal comprises: at least an A element, which is Eu; an M element, which is Ca; Si; Al; oxygen; and nitrogen, wherein the α-type sialon crystal is expressed by a general formula: (M x ,A y )(Si 12−(m+n) Al m+n )(O n N 16−n ) (1), and m=δ M ×x+δ A ×y (2), wherein the α-type sialon crystal is expressed by a composition formula having parameters x, y, m, and n, which are in a range expressed by: 0.2≦x≦2.4 (3), 0.001≦y≦0.4 (4), 0.5×m<n≦4 (5), 0.6≦m≦1.4 (7), and 0.8≦n≦2 (8); wherein x is an amount of solid solution of M in a sialon unit cell, y is an amount of solid solution of A in the sialon unit cell, and n is a content amount of oxygen in the sialon unit cell; and wherein the phosphor emits fluorescence having a peak in a wavelength range from 560 nm to 575 nm upon irradiation of an excitation source.