Sapphire *
* Single crystal alumina (Al2O3)
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More than 98% LEDs are based on sapphire

Excellent physical and chemical properties of sapphire make it an indispensable component for a variety hi-tech applications. Sapphire crystal lattice is the best match for mass production of nitride-based light emitting diodes (LEDs).

sapphire substrate for LEDs

Versatile material of the future

The latest achievements in sapphire growing and processing make it available for a variety of new promising applications including consumer electronics, dentistry, spacecraft windows and RFICs. Unparalleled hardness, outstanding chemical resistance, low refractive index and melting point over 2000 °C make synthetic sapphire a versatile material of the future.

Sapphire properties

General
Chemical composition: Al2O3
Growing method: Kyropoulos
Crystal structure: hexagonal
a = b = 4.77 A
c = 13.04 A
Thermal
Melting point: 2050 °C
Linear expansion coefficient: 6,7 x 10-6 / °C parallel to С axis
5.0 x 10-6 / °C perpendicular to С axis
Thermal conductivity: 46,06 W/м °K (0°C)
Mechanical
Density 3,98 g/sm3
Hardness Mohs: 9
Knoop: 1800 daN/mm2 parallel to С axis
2200 daN/mm2 perpendicular to С axis
Tensile strength: 400 MPa/mm2 (25°C) 275 MPa/mm2 (500°C) 345 MPa/mm2 (1000°C)
Flexural strength: 35 до 39 daN/mm2
Compression stress: 2,0 GPa
Young's modulus 3,6 x 104 до 4,4 x 104 daN/mm2
Electric
Dielectric permeability: 9,3 (103 - 109 Гц, 25°C) perpendicular to С axis
11,5 (103 - 109 Гц, 25°C) parallel to С axis
Specific resistivity: 1016 Ом/см (25°C)
1011 Ом/см (500°C)
106 Ом/см (1000°C)



 
 
 

Sapphire parameters

Resistant to high temperatures Melts only at 2050°C. Chemically inert at high temperature
Hard and durable
  • Scratch resistant to all materials but diamond
  • High pressure resistant
  • Abrasion resistant
Resistant to most agressive environments
  • Long-life performance, e.g. 5 times longer than quartz
  • High chemical purity
Wide transmittance range from UV to IR 80~90% at 0,25 - 4,50 um
High thermal conductivity Provides rapid heating and cooling