Optics >>> Optical Material >>> Sapphire

Sapphire is a single crystal aluminum oxide (Al2O3). 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.


  • Transparence range: 0.18- 4.5μm 
  • Density: 3.98g/cm3 
  • Mohs hardness: 9 
  • Melting point: 2030o
  • Thermal conductivity: 0.04W/m/K 
  • Expansion coefficient: 8.4x10-6/K 
  • Refractive Index: 1.755@1m 

Transmission Curve:

Physical Properties
Crystal Symmetry  Hexagonal
Lattice constant a =4.75
c =12.97
Transparence range 0.18- 4.5 μm
Density 3.98g/cm3
Mohs hardness
Melting point 2030oC
Thermal conductivity 0.04 W/m/K
Expansion coefficient (10-6/K) 8.4 
Refractive Index (1.0 μm) 1.755


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