Sodium Fluoride (NaF)
| Crystal properties | ||
| Crystal Type | cubic | |
| Transmission Range | < 0.15 ... 15 µm | |
| Refractive Index | 1.233 @ 10.3 µm | |
| Reflective Loss | 3.6 % @ 4.0 µm | |
| Reststrahlen | 35.8 µm | |
| Density | 2.726 g/cm3 | |
| Melting Point | 980 °C / 997 °C | |
| Molecular Weight | 41.988 | |
| Thermal Conductivity | 3.746 W / (m K) | |
| Specific Heat | 1088 J / (kg K) @ 0 °C | |
| Thermal Expansion | 36 × 10–6 / K @ 25 °C | |
| Hardness (Knoop) | 60 | |
| Young’s Modulus | 64.79 GPa | |
| Shear Modulus | 55.14 GPa | |
| Bulk Modulus | 62.03 GPa | |
| Elastic Coefficient | C11 = 90.9 / C12 = 26.4 / C44 = 12.7 GPa | |
| Dielectric Constant | 6.0 @ f = 2 MHz | |
| Solubility in Water | 4.22 g / 100 g @ 18 °C | |
| Cleavage Planes | (100) | |
| Standard Diameter | 200 mm larger diameters on request |
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| Application | Cherenkov-counter AR coating material |
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| Remarks | very low refractive index | |
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