Phosphor, light-emitting device including said phosphor, projector, head-up display and vehicle including said light-emitting device

1. A phosphor comprising a host crystal including Sr 3 MgSi 2 O 8 crystal and SrMgSiO 4 crystal, the phosphor being a blue phosphor including Eu 2+ as a luminescent center or being a blue and red dual emission phosphor including Eu 2+ and Mn 2+ as luminescent centers.

2. A phosphor comprising a host crystal including Sr 3 MgSi 2 O 8 crystal and SrMgSiO 4 crystal, the phosphor being a blue phosphor including Eu 2+ as a luminescent center, and being free from Mn 2+ as a luminescent center.

3. The phosphor according to claim 1 , wherein the phosphor has diffraction peaks at 2θ of 22° to 23°, 2θ of 30.6° to 31.7° and 20 of 31.8° to 32.8° and also has diffraction peaks at 2θ of 28° to 30.4° and 2θ of 34° to 35.5° in an X-ray diffraction pattern measured with Cu—Kα radiation.

4. The phosphor according to claim 1 , wherein the phosphor satisfies 0.01≦a≦0.18 wherein a is a value of the ratio c/b wherein b is the intensity of the largest diffraction peak assigned to the Sr 3 MgSi 2 O 8 crystal present at 2θ of 31.8° to 32.8° in an X-ray diffraction pattern of the phosphor measured with Cu—Kα radiation, and c is the intensity of the largest diffraction peak assigned to the SrMgSiO 4 crystal present at 2θ of 34° to 35.5° in the X-ray diffraction pattern.

5. The phosphor according to claim 1 , wherein the host crystal of the phosphor has a composition represented by the general formula Sr 3+j Mg 1+k Si 2+m O 8+n (0<j≦1.0, 0<k≦1.0, 0<m≦1.0, and 0<n≦4.0).

6. A light-emitting device comprising a phosphor layer containing a phosphor, the phosphor including a host crystal including Sr 3 MgSi 2 O 8 crystal and SrMgSiO 4 crystal, the phosphor being a blue phosphor including Eu 2+ as a luminescent center or being a blue and red dual emission phosphor including Eu 2+ and Mn 2+ as luminescent centers.

7. The light-emitting device according to claim 6 , further comprising a semiconductor light-emitting element that emits light having a peak wavelength in the wavelength range of 380 nm to 420 nm, wherein the phosphor in the phosphor layer absorbs at least part of the light emitted from the semiconductor light-emitting element and emits light having a peak wavelength longer than the light absorbed by the phosphor.

8. The light-emitting device according to claim 7 , wherein the semiconductor light-emitting element comprises an emitting layer including a gallium nitride compound semiconductor.

9. A projector comprising the light-emitting device of claim 6 .

10. The projector according to claim 9 , further comprising an image generator that generates an image using light emitted from the light-emitting device, and an output optical system that outputs the image generated by the image generator.

11. A vehicle comprising the light-emitting device of claim 6 .

12. The vehicle according to claim 11 , comprising a headlight including the light-emitting device and an output optical system that outputs light from the light-emitting device toward the front of the headlight.

13. A head-up display comprising the light-emitting device of claim 6 .

14. The head-up display according to claim 13 , further comprising an image generator that generates an image using light emitted from the light-emitting device, and an output optical system that outputs the image generated by the image generator.