Optical Silicon vs. Fused Silica
Optical silicon belongs to the non-glass optical ceramics classification, while fused silica belongs to the glass and glass-ceramics. There are 22 material properties with values for both materials. Properties with values for just one material (5, in this case) are not shown.
For each property being compared, the top bar is optical silicon and the bottom bar is fused silica.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 120 | |
| 1100 |
| Elastic (Young's, Tensile) Modulus, GPa | 150 | |
| 73 |
| Flexural Strength, MPa | 300 | |
| 67 |
| Knoop Hardness | 1130 | |
| 570 |
| Poisson's Ratio | 0.28 | |
| 0.17 |
| Shear Modulus, GPa | 80 | |
| 31 |
| Tensile Strength: Ultimate (UTS), MPa | 110 | |
| 50 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 1350 | |
| 1080 |
| Melting Onset (Solidus), °C | 1560 | |
| 1900 |
| Specific Heat Capacity, J/kg-K | 700 | |
| 720 |
| Thermal Conductivity, W/m-K | 150 | |
| 1.4 |
| Thermal Expansion, µm/m-K | 3.0 | |
| 0.5 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 MHz | 12 | |
| 3.8 |
Otherwise Unclassified Properties
| Density, g/cm3 | 2.3 | |
| 2.2 |
| Light Transmission Range, µm | 1.2 to 15 | |
| 0.16 to 3.5 |
| Refractive Index | 3.5 | |
| 1.5 |
Common Calculations
| Stiffness to Weight: Axial, points | 35 | |
| 18 |
| Stiffness to Weight: Bending, points | 75 | |
| 63 |
| Strength to Weight: Axial, points | 13 | |
| 6.3 |
| Strength to Weight: Bending, points | 22 | |
| 14 |
| Thermal Diffusivity, mm2/s | 93 | |
| 0.85 |
| Thermal Shock Resistance, points | 18 | |
| 97 |