Molecular formula

Al203

Density 

3.95-4.1g/cm ³

Crystalstructure

Hexagonal crystal

Lattice constant

a =4.785A,c=12.991A

Mohs hardness

9（below the diamond：10）

Melting point

2045°C

Boiling point

3000°C

Thermal expansivity

5.8×10-6/K

Specific heat

0.418W.s/g/k

Thermal conductivity

25.12W/m/k(@100°C)

Refractive index

no=1.768  ne=1.760

dn/dt

13×10-6/K(@633nm)

Light penetration

T≈80%（0.3~5μm）

Permittivity

11.5（//c）,9.3(丄c)