Yellow fluorescent substance, light-emitting device, illumination device, and vehicle
The present invention provides an oxynitride silicate fluorescent substance capable of output a light having a high luminance even when irradiated by an exciting light having a high energy density. The present invention is a yellow fluorescent substance represented by a chemical formula (Ba 1-x-y-z ,Sr x ) a Si b O c N d :Eu 2+ y ,Y 3+ z (0.9≦a≦1.1, 1.9≦b≦2.1, 1.9≦c≦2.1, 1.9≦d≦2.1, 0≦x≦1, 0<y<0.01, and 0≦z<0.01).
1. A yellow fluorescent substance represented by a chemical formula (Ba 1-x-y-z ,Sr x ) a Si b O c N d :Eu 2+ y ,Y 3+ z , wherein
all of the following seven mathematical formulae (I)-(VII) are satisfied:
0.9≦ a≦ 1.1 (I)
1.9≦ b≦ 2.1 (II)
1.9≦ c≦ 2.1 (III)
1.9≦ d≦ 2.1 (IV)
0≦ x≦ 1 (V)
0< y< 0.01 (VI)
0≦ z< 0.01 (VII).
2. The yellow fluorescent substance according to claim 1 , wherein all of the following three mathematical formulae (Va)-(VIIa) are satisfied:
0.3 ≦x< 0.7 (Va)
0.0001≦ y< 0.01 (VIa)
0≦ z< 0.01 (VIIa).
3. The yellow fluorescent substance according to claim 1 , wherein the following mathematical formula (VIb) is further satisfied:
0.001≦ y< 0.01 (VIb).
4. The yellow fluorescent substance according to claim 1 , wherein the following mathematical formula (VIIb) is further satisfied:
0< z< 0.01 (VIIb).
5. The yellow fluorescent substance according to claim 4 , wherein
y=z.
6. A light-emitting device, comprising:
the yellow fluorescent substance according to claim 1 ; and
a light-emitting element.
7. The light-emitting device according to claim 6 , further comprising:
a blue fluorescent substance.
8. The light-emitting device according to claim 6 , wherein
the light-emitting element comprises a light-emitting layer formed of a nitride semiconductor having a growth surface of a non-polar or semi-polar plane.
9. The light-emitting device according to claim 6 , wherein
the light-emitting element emits light having a peak wavelength of not less than 380 nanometers and not more than 480 nanometers.
10. The light-emitting device according to claim 6 , wherein
the light-emitting element is a laser diode.
11. The light-emitting device according to claim 6 , wherein
the light-emitting element has an energy density of not less than 0.1 kW/cm 2 .
12. An illumination device comprising the light-emitting device according to claim 6 .
13. The illumination device according to claim 12 , wherein
the illumination device is a vehicle illumination device.
14. A vehicle comprising the vehicle illumination device according to claim 13 .