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Synthetic Sapphire vs. Gallium Arsenide

Synthetic sapphire belongs to the oxide-based engineering ceramics classification, while gallium arsenide belongs to the non-glass optical ceramics. There are 13 material properties with values for both materials. Properties with values for just one material (12, in this case) are not shown.

For each property being compared, the top bar is synthetic sapphire and the bottom bar is gallium arsenide.

Metric UnitsUS Customary Units

Mechanical Properties

Elastic (Young's, Tensile) Modulus, GPa 450
85
Knoop Hardness 1860
750
Poisson's Ratio 0.28
0.31

Thermal Properties

Melting Onset (Solidus), °C 2050
1400
Specific Heat Capacity, J/kg-K 760
360
Thermal Conductivity, W/m-K 30
47
Thermal Expansion, µm/m-K 5.3
5.6

Otherwise Unclassified Properties

Density, g/cm3 4.0
5.3
Light Transmission Range, µm 0.17 to 5.5
1.0 to 16
Refractive Index 1.8
3.4

Common Calculations

Stiffness to Weight: Axial, points 63
8.9
Stiffness to Weight: Bending, points 64
28
Thermal Diffusivity, mm2/s 9.9
25