Quartz crystals and fused silica are very interesting optical materials due to the combination of many interesting properties. They are totally transparent, exhibit excellent UV to IR transmission, are extremely water and chemical element resistant, have a very low coefficient of thermal elongation, and even exhibit higher thermal shock resistance than borosilicates. Using quartz crystal and fused silica materials, Alfa Chemistry can produce optical components on demand in practically any shape or size according to customer specifications. Contact us if you require assistance.
Advantages of Quartz/Fused Silica
Quartz crystals and fused silica are both extremely pure, have high working and melting temperatures, very little thermal expansion, and superior optical quality. With a maximum service temperature of 1450 ℃ and a long-term use temperature of 1100 ℃, the softening point is roughly 1730 ℃. Both are resistant to corrosion, with stainless steel having 150 times the corrosion resistance of ceramic and 30 times that of acid. Except for hydrofluoric acid, there is seldom any reactivity to acids. It is perfect for usage in the precision optics sector because to the aforementioned qualities.
Fig 1. (a) Real and (b) imaginary parts of the complex refractive index of fused silica close to its phonon resonances. (Shahsafi A, et al. 2018)
Fused silica is a high-purity, non-crystalline material made by oxidizing raw silica in a flame hydrolysis process. Quartz, on the other hand, is made from crystalline quartz. Due to this distinction, fused quartz has a far higher UV transmission than quartz. Quartz also has a much lower OH content. Alpha quartz is common and is typically rotated RH. On request, LH rotated is available. Crystalline quartz is frequently employed as a wave delay medium in optics. Quartz's birefringent characteristics can be applied to quarter-wave plates and polarizers.
Properties of Quartz/Fused Silica
| Performance | Optimum Transmission Range | |
|---|---|---|
| Ultraviolet (UV) Fused Silica | Excellent transmission in deep UV. Excellent throughput Uniformity, non-fluorescence and thermal shock resistance | 180 nm ~ 2.0 µm |
| Infrared (IR) Fused Silica | Remove OH- ion impurities Higher transmittance Thermal shock resistance and high homogeneity | 250 nm ~ 3.6 µm |
| Quartz Crystal | |
|---|---|
| Density | 2.649 g/cc |
| Molecular Weight | 60.06 |
| Solubility | Insoluble in water |
| Class/Structure | Trigonal (hex) P3(2)21 (RH) and P3(1)21 (LH) |
| Melting Point | 1710 ℃ |
| Hardness | Knoop 741 with 500g indenter |
| Refractive Index | No 1.54421; Ne 1.55333 at 0.6 μm |
| Transmission Range | 0.18 ~ 3.5 μm |
| Reflection Loss | 8.8% at 0.6 μm |
| Apparent Elastic Limit | 41MPa (5950psi) |
| Dielectric Constant | 4.34 (para) 4.27 (perp) at 30MHz |
| dn/dT | 5x10-6/℃ |
| Youngs Modulus (E) | 97.2 (para) 76.5 (perp) GPa |
| Shear Modulus (G) | 31.14 GPa |
| Bulk Modulus (K) | 36.4 GPa |
| Thermal Expansion | 7.1 (para) 13.2 (perp) x 10-6/℃ |
| Thermal Conductivity | 10.7 (para) 6.2 (perp) W/m/K at 323 K |
| Specific Heat Capacity | 710 J Kg-1 K-1 |
| Apparent Elastic Limit | C11=87 C12=7 C44=58 C13=13 C14=(-)18 C33=106 |
About refractive index parameters.
"No" means ordinary light, "Ne" means extraordinary light.
| Quartz Crystal | ||||||||
|---|---|---|---|---|---|---|---|---|
| µm | No | Ne | µm | No | Ne | µm | No | Ne |
| 0.193 | 1.661 | 1.675 | 0.213 | 1.632 | 1.645 | 0.222 | 1.622 | 1.634 |
| 0.226 | 1.619 | 1.630 | 0.248 | 1.602 | 1.613 | 0.257 | 1.596 | 1.607 |
| 0.280 | 1.585 | 1.596 | 0.308 | 1.576 | 1.586 | 0.325 | 1.571 | 1.581 |
| 0.351 | 1.565 | 1.575 | 0.400 | 1.558 | 1.567 | 0.458 | 1.552 | 1.561 |
| 0.488 | 1.550 | 1.559 | 0.515 | 1.548 | 1.557 | 0.532 | 1.547 | 1.556 |
| 0.590 | 1.544 | 1.553 | 0.633 | 1.543 | 1.552 | 0.670 | 1.541 | 1.551 |
| 0.694 | 1.541 | 1.550 | 0.755 | 1.539 | 1.548 | 0.780 | 1.539 | 1.548 |
| 0.800 | 1.538 | 1.547 | 0.820 | 1.538 | 1.547 | 0.860 | 1.537 | 1.547 |
| 0.980 | 1.535 | 1.546 | 1.064 | 1.534 | 1.543 | 1.320 | 1.531 | 1.539 |
| 1.550 | 1.528 | 1.536 | 2.010 | 1.521 | 1.529 | |||
Reference
- Shahsafi A, et al. (2018). "Mid-infrared Optics Using Dielectrics with Refractive Indices Below Unity." Physical Review Applied. 10(3): 034019.