Optics Materials

Sapphire

Sapphire

Sapphire is a single crystal aluminum oxide (Al 2 O 3 ). It is one of the hardest materials. sapphire has good transmission characteristics over the visible, and near IR spectrum. It exhibits high mechanical strength, chemical resistance, thermal conductivity and thermal stability. It is often used as window materials in specific field such as space technology where scratch or high temperature resistance is required. 

Physical Properties

Crystal Symmetry Hexagonal
 
System
Lattice constant
A
a =4.75 ; c =12.97
Transparence range
μm
0.18- 4.5
Density
g/cm 3
3.98
Mohs hardness
 
9
Melting point
2030
Thermal conductivity
W/m/K
0.04
Expansion coefficien
10 -6 /K
8.4
Refractive Index
1.0 m m
1.755

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