Glass ceramic body, substrate for mounting light-emitting element, and light emitting device

1. A glass ceramic body comprising:

a glass matrix; and

a ceramic part comprising alumina particles, the alumina particles being dispersed in the glass matrix, wherein the glass matrix is not crystallized, the ceramic part comprises an α-alumina crystal structure and a crystal structure other than the α-alumina crystal structure, and the alumina particles have a flat shape and are dispersed in the glass matrix such that the thickness direction of each alumina particle is substantially the same direction.

2. The glass ceramic body according to claim 1 , wherein in a cross-section along the thickness direction of the glass ceramic body, the average length of the flat direction of the alumina particles is from 2 to 10 μm, and the average length of the thickness direction of the alumina particles is from 0.05 to 0.5 μm.

3. The glass ceramic body according to claim 1 , wherein in a cross-section along the thickness direction of the glass ceramic body, the area of the flat alumina particles per unit area is from 30 to 50%.

4. The glass ceramic body according to claim 2 , wherein in a cross-section along the thickness direction of the glass ceramic body, the area of the flat alumina particles per unit area is from 30 to 50%.

5. The glass ceramic body according to claim 1 , wherein when the total proportion of the α-alumina crystal structure and the crystal structure other than the α-alumina crystal structure is 100%, the proportion of the crystal structure other than the α-alumina crystal structure is from 1 to 70%.

6. The glass ceramic body according to claim 1 , wherein the glass ceramic body has a flexural strength of at least 180 MPa.

7. The glass ceramic body according to claim 1 , wherein the glass matrix comprises SiO 2 —B 2 O 3 glass containing from 15 to 40 mol% of CaO as represented by oxides base.

8. The glass ceramic body according to claim 1 , wherein the glass ceramic body contains substantially no mullite crystal.

9. The glass ceramic body according to claim 1 , wherein the glass ceramic body contains substantially no alumina particles having a Υ-alumina crystal structure.

10. The glass ceramic body according to claim 1 , wherein the crystal structure other than the α-alumina crystal structure is at least one crystal structure selected from the group consisting of a δ-alumina, a θ-alumina, an η-alumina, a χ-alumina and a κ-alumina.

11. The glass ceramic body according to claim 1 , wherein the crystal structure other than the α-alumina crystal structure is a θ-alumina crystal structure.

12. A substrate for mounting a light emitting element, comprising the glass ceramic body as defined in claim 1 .

13. A light emitting device comprising:

the substrate as defined in claim 12 ; and

a light emitting element mounted on the substrate.

14. The glass ceramic body according to claim 1 , wherein a difference between a refractive index of glass constituting the glass matrix and a refractive index of alumina is at least 0.15.

15. The glass ceramic body according to claim 1 , wherein a difference between a refractive index of glass constituting the glass matrix and a refractive index of alumina is at least 0.19.

16. The glass ceramic body according to claim 1 , wherein when the total proportion of the α-alumina crystal structure and the crystal structure other than the α-alumina crystal structure is 100%, the proportion of the crystal structure other than the α-alumina crystal structure is from 5 to 60%.

17. The glass ceramic body according to claim 1 , wherein in a cross-section along the thickness direction of the glass ceramic body, the area of the flat alumina particles per unit area is from 35 to 45%.