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Technical Data > Sapphire properties
Properties Units Sapphire
(parallel to C axis)
Sapphire
(perpendicular to C axis)
Alumina 99.9 % Alumina 99.5 % Quartz Silicon Carbide Silicon Nitride Aluminum Nitride
Density g/cm3 3.97 3.97 3.96 3.98 2.2 3.1 3.18-3.30 3.25
Young's Modulus Gpa at R.T 435   386 372 70 393 311 300
Modulus of rigidity (shear) Gpa at R.T 175   158 152 31 166    
Poisson's Ratio   0.27-0.30 0.27-0.30 0.22 0.22 0.17 1.19    
Flexural Strength MPa 1035 760 550 350 80 462 338-900 300
Compressive Strength MPa at R.T 2000   3700 2600 550-1100 2500    
Hardness Knoop 1900 2200 1440 1551 1250 2500   1050
Volume Resistivity ohm-cm at R.T 1 x 10 16 1 x 10 16 1 x 10 14 1 x 10 14 7 x 10 7 1 x 10 8 1 x 10 12 1 x 10 14
Dielectric Strength volts/cm 480000 480000 315000 331000 500000      
Dielectric Constant 10 3 -10 9 Hz 11.5 9.3 9.8 9.7 3.75     8.5
Loss Tangent * 10 5 @ 10 10 Hz 8.6 3.0 2.0 2.0 0.4      
Magnetic Susceptability * 10 6 -0.21 -0.25            
Melting Point 0C 2053 2053     1683      
Maximum usable temperature 0C 2000 2000 1900 1750 1200 1400 1200-1400 1600
Specific Heat cal/g0 K at R.T 0.181 0.181 0.21 0.20 0.16 0.15 0.17  
Thermal Conductivity watts/m0 K at R.T 40 40 39 36 1.4 125 12--15 115
Coefficient of Thermal Expansion * 10 -6 at 25-10000C 8.8 7.9 8.4 8.2 0.55 4.3 3.0 5.7
Refractive index   1.768 1.76 opaque opaque 1.46 opaque opaque opaque
Optical Transmission Range(80%) nm (100cm thick) 200-3500 200-3500 opaque opaque 270-2400 opaque opaque opaque
Technical Data