Patent ID: 8704439

Claim:
A blue light-emitting phosphor for the use as a blue light-emitting material to be placed in a light-emitting device which comprises a semiconductor element emitting a light in the wavelength region of 350 to 430 nm by applying electric energy and a blue light-emitting material emitting a blue light when excited with the light emitted by the semiconductor element, which has an elemental formula of Sr 3-x MgSi 2 O 8 :Eu x in which x is a value in the range of 0.008 to 0.110, a merwinite crystal structure, and a crystal lattice strain of 0.080% or less, the crystal lattice strain being determined from an X-ray diffraction pattern in the region of 20 to 130° in terms of a diffraction angle 2θ by the Le Bail method, the X-ray diffraction pattern being obtained using CuKα ray having an incident angle of θ.