|
| Characteristics of
Single Crystal Sapphire |
Polishing sapphire
creates an ideal surface smoothness and precision due to its characteristics,
such as thermo conductivity, insulation ability, chemical, heat, and abrasion
resistance.
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|
Chemical composition |
Al2O3 |
Crystal system |
Hexagonal system a=4.763Å
c=13,003Å |
Hardness |
Mohs hardness 9
Knoop hardness perpendicular to the c axis
1.525 to 1.660 kgf/mm2
Knoop hardness parallel to the c axis 1.670
to 2.000 kgf/mm2 |
Specific gravity |
3.98g/cm3 |
Fusing temperature |
2.040℃ |
Thermal conductivity |
0.1 cal/cm sec°C at 20℃
0.06 cal/cm sec°C at 100℃ |
Thermal expansion coefficient
(mean value from
25℃) |
|
Perpendicular to the c axis |
Parallel to the c axis |
50℃ |
50 x 10-7cm/cm℃ |
67×10-7cm/cm℃ |
500℃ |
50 x 77-7cm/cm℃ |
67 x 83-7cm/cm℃ |
1,000℃ |
50 x 83-7cm/cm℃ |
67 x 90-7cm/cm℃ |
|
Refractive index[24°C] |
6563Å |
nc |
perpendicular to the c axis 1.765 |
parallel to the c axis 1.757 |
5893Å |
no |
perpendicular to the c axis 1.768 |
parallel to the c axis 1.760 |
4861Å |
nf |
perpendicular to the c axis 1.775 |
parallel to the c axis 1.767 |
|
Dielectric constant |
9.0 at 105 Hz and 11.0 at 10 GHz on the c
axis |
Threshold voltage |
480,000V/cm |
Dielectric strength |
20,800kg/cm2 |
Destruction coefficient |
5,000～7,000kg/cm2 |
Young's modulus |
3.5～3.8×106Kg/cm2 |
Volume-specific resistance |
500℃ |
1011Ωcm |
1,000℃ |
108Ωcm |
1,500℃ |
104Ωcm |
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