SapphireSapphire (Al2O3) boasts superior optical, mechanical and chemical properties to other common optical glasses and crystals. With a hardness of 9 Mhos and chemical inertness Sapphire windows are utilized in high pressure systems and in applications where other materials suffer from scratching and chipping from abrasive, gritty and otherwise hazardous environments.

Sapphire's wide transmission range allows it to be used in all visible applications and increasingly in NIR systems, particularly in optical defence applications such as imaging system covers and missile domes.

In addition to its mechanical durability Sapphire's resistance to thermal shock and prolonged high temperature stability (>1500C) make it ideal for high pressure and temperature applications, from portholes in oil and gas systems to vacuum chambers and spectroscopy instruments.

Below are listed common Sapphire forms and component types offered by Roditi; choose one of the categories to find out more about our capabilities. In addition to the following forms, Roditi offer highly customised Sapphire components. Contact us directly to discuss your specifications and requirements.

Sapphire Materials

  • Boules
  • Blanks
  • Ingots

Sapphire Flats

  • Windows
  • Wafers
  • Discs
  • Plates

Sapphire Components

  • Tubes
  • Pins
  • Rods
  • Prisms
  • Lightguides

Specialist Sapphire

  • Domes
  • Wafer Carriers
  • Crucibles

Sapphire Properties

Chemical Formula
Crystal Stucture
Hexagonal System ((hk o 1)
Unit Cell Dimension
a=4.758 Å,Å c=12.991 Å, c:a=2.730
English (Imperial)
3.98 g/cc
0.144 lb/in3
1525 - 2000 Knoop,  9 mhos
3700° F
Melting Point
2310 K (2040° C)
Tensile Strength
275 MPa to 400 MPa
40,000 to 58,000 psi
at 20°
400 MPa
58,000 psi (design min.)
at 500° C
275 MPa
40,000 psi (design min.)
at 1000° C
355 MPa
52,000 psi (design min.)
Flexural Stength
480 MPa to 895 MPa
70,000 to 130,000 psi
Compression Strength
2.0 GPa (ultimate)
300,000 psi (ultimate)
Young's Modulus, E
345 GPa
50 x 106 psi
(Modulus of Elasticity)
Bulk Modulus, k
250 GPa
36 x 106 psi
(Modulus of Compression)
Shear Modulus, G
145 GPa
21 x 106 psi
(Modulus of Rigidity)
350 MPa to 690 MPa
50,000 to 100,000 psi
(Modulus of Rupture)
Poisson's Ratio
Sapphire is anisotropic.  It is orientation dependent.
Thermal Conductivity
at 0° C
46.06 W/(m • K)
319.4 BTU in/hr ft2 °F
(60° orientation)
at 100° C
25.12 W/(m • K)
174.2 BTU in/hr ft2 °F
at 400° C
12.56 W/(m • K)
87.1 BTU in/hr ft2 °F
Specific Heat at 20° C
0.187 cal/(g • °C)
0.1827 BTU/lb °F
Heat Capacity
at 20° C
18.63 cal/ (mole • °C)
18.6 BTU/lb mole °F
at 1000° C
29.86 cal/ (mole • °C)
29.9 BTU/lb mole °F
Thermal Expansion Coefficient
20° to 50° C
5.8 x 10-6/ °C
3.2 x 10-6/ °F
(60 degree orientation)
20° to 500°C
7.7 x 10-6/ °C
4.3 x 10-6/ °F
E l to C axis
E ll to C axis
Loss Tangent
Loss Tangent
1 MHz
3 GHz
8.5 GHz
Volume Resistivity at 25 °C
1014 ohm • cm

Sapphire is, as stated above, an anisotropic crystal, and the values given above are average values. Please remember that this engineering data is representative only, and should not be considered absolute or warrantable.

To discuss Sapphire or any of Roditi's other products, please contact us.