Light emitting device and illumination apparatus

A light-emitting device comprising:

• a semiconductor light-emitting element that emits blue-violet or blue light;
• and
• a fluorescent material that absorbs all or a part of the blue-violet or blue light emitted by the semiconductor light-emitting element and emits fluorescence of wavelengths different from that of the blue-violet or blue light,
• wherein the fluorescent material comprises a mixture of a first fluorescent material that emits green or yellow-green light, a second fluorescent material that has a longer emission wavelength than that of the first fluorescent material and emits yellow-green, yellow, or yellow-red light, and a third fluorescent material that has a longer emission wavelength than the second fluorescent material and emits yellow-red or red light,
• the first fluorescent material is a europium-activated β-SiAlON fluorescent material, the second fluorescent material is a europium-activated α-SiAlON fluorescent material, and the third fluorescent material is a nitride crystalline red fluorescent material expressed by the general formula of (Ca,Eu)AlSiN3, and
• the α-SiAlON fluorescent material is expressed by a formula of CaqEur(Si,Al)12(O,N)16 in which q is between about 0.75 and about 1.0 and r is between about 0.03 and about 0.07 and has a primary phase of an α-SiAlON crystalline structure.

A light-emitting device comprising:

• a semiconductor light-emitting element that emits blue-violet or blue light;
• and a fluorescent material that absorbs all or a part of the blue-violet or blue light emitted by the semiconductor light-emitting element and emits fluorescence of wavelengths different from that of the blue-violet or blue light, wherein
• the fluorescent material comprises a mixture of a first fluorescent material that emits green or yellow-green light, a second fluorescent material that has a longer emission wavelength than that of the first fluorescent material and emits yellow-green, yellow, or yellow-red light, and a third fluorescent material that has a longer emission wavelength than the second fluorescent material and emits yellow-red or red light,
• the first fluorescent material is a europium-activated β-SiAlON fluorescent material, the second fluorescent material is a europium-activated α-SiAlON fluorescent material, and the third fluorescent material is a nitride crystalline red fluorescent material expressed by the general formula of (Ca,Eu)AlSiN3, and
• the β-SiAlON fluorescent material is expressed by a formula Eus(Si,Al)6−s(O,N)8 in which s is between about 0.011 and about 0.019 and has a primary phase of a β-SiAlON crystalline structure.

An illumination apparatus comprising:

• a light source including a light emitting device comprising:
• a semiconductor light-emitting element that emits blue-violet or blue light;
• and
• a fluorescent material that absorbs all or a part of the blue-violet or blue light emitted by the semiconductor light-emitting element and emits fluorescence of wavelengths different from that of the blue-violet or blue light,
• wherein the fluorescent material comprises a mixture of a first fluorescent material that emits green or yellow-green light, a second fluorescent material that has a longer emission wavelength than that of the first fluorescent material and emits yellow-green, yellow, or yellow-red light, and a third fluorescent material that has a longer emission wavelength than the second fluorescent material and emits yellow-red or red light, and
• the first fluorescent material is a europium-activated β-SiAlON fluorescent material, the second fluorescent material is a europium-activated α-SiAlON fluorescent material, and the third fluorescent material is a nitride crystalline red fluorescent material expressed by a formula of (Ca,Eu)AlSiN3.