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Single Cristal Sapphire

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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.

Chemical composition

Al2O3

Crystal system
Hexagonal system@a=4.763ð c=13,003ð
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Ž

Thermal conductivity
0.1 cal/cm sec°C at 20Ž
0.06 cal/cm sec°C at 100Ž
Thermal expansion coefficient
(mean value from 25Ž)

 

Perpendicular to the c axis
Parallel to the c axis

50Ž

50 x 10-7cm/cmŽ

 67×10-7cm/cmŽ

500Ž

 50 x 77-7cm/cmŽ

67 x 83-7cm/cmŽ

1,000Ž

50 x 83-7cm/cmŽ
67 x 90-7cm/cmŽ
Refractive index[24°C]

 6563ð

nc

perpendicular to the c axis 1.765 parallel to the c axis 1.757

5893ð

no

perpendicular to the c axis 1.768 parallel to the c axis 1.760

4861ð

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Ž

1011Ħcm

1,000Ž

108Ħcm

1,500Ž

104Ħcm

 

 

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