Zirconia composition, zirconia semi-sintered body and zirconia sintered body, as well as dental product

1. A partially stabilized zirconia sintered body, comprising from 4 mol % to 7 mol % of yttria as a stabilizer,

wherein

the zirconia sintered body comprises a light shielding material,

the zirconia sintered body comprises a first region, and a second region having a higher content ratio of the light shielding material than the first region,

a difference between a content ratio of yttria in the first region and a content ratio of yttria in the second region is 1 mol % or less,

a L* value of color degree in a L*a*b* color system measured on white background is defined as a first L* value,

the L* value of color degree in the L*a*b* color system measured on black background is defined as a second L* value, and

ΔL of the first region is larger than ΔL of the second region, wherein a value calculated by subtracting the second L* value from the first L* value is defined as ΔL.

2. The partially stabilized zirconia sintered body according to claim 1 , wherein ΔL of the first region is by 0.8 or more larger than ΔL of the second region.

3. The partially stabilized zirconia sintered body according to claim 1 , wherein ΔL of the first region is from 8 to 12 and ΔL of the second region is from 4 to 11.

4. The partially stabilized zirconia sintered body according to claim 1 , wherein ΔL of the second region is 7.5 or less.

5. The partially stabilized zirconia sintered body according to claim 1 , wherein the first region and the second region are laminated.

6. The partially stabilized zirconia sintered body according to claim 1 , wherein:

the zirconia sintered body further comprises a third region between the first region and the second region, and

ΔL of the third region is larger than ΔL of the second region and smaller than ΔL of the first region.

7. The partially stabilized zirconia sintered body according to claim 6 , wherein a content ratio of the light shielding material in the third region is higher than a content ratio of the light shielding material in the first region and lower than a content ratio of the light shielding material in the second region.

8. The partially stabilized zirconia sintered body according to claim 6 , wherein:

the zirconia sintered body further comprises a fourth region between the third region and the second region, and

ΔL of the fourth region is larger than ΔL of the second region and smaller than ΔL of the third region.

9. The partially stabilized zirconia sintered body according to claim 8 , wherein a content ratio of the light shielding material in the fourth region is higher than the content ratio of the light shielding material in the third region and lower than the content ratio of the light shielding material in the second region.

10. The partially stabilized zirconia sintered body according to claim 8 , wherein with respect to thickness in a laminated direction of each region,

a thickness of the first region is from 30% to 40% of a total thickness,

a thickness of the second region is from 30% to 40% of the total thickness,

a thickness of the third region is from 10% to 20% of the total thickness, and

a thickness of the fourth region is from 10% to 20% of the total thickness.

11. The partially stabilized zirconia sintered body according to claim 1 , wherein the light shielding material is at least one selected from a group consisting of silicon oxide, aluminium oxide, titanium oxide, a complex oxide of zirconium and silicon, a coloring agent and a fluorescence agent.

12. The partially stabilized zirconia sintered body according to claim 1 , wherein the partially stabilized zirconia contains 5.3 mol % to 6.2 mol % of yttria as the stabilizer.