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Silver Chloride AgCl
Silver Chloride is a useful material for deep IR applications where sensitivity to moisture is a problem. This soft crystal deforms under heat and pressure and can be forged in polished dies to create IR windows and lenses. A major use for Silver Chloride is in the manufacture of small disposable cell windows for spectroscopy, known as mini-cells. These windows have a depression of controlled thickness pressed into the surface. The inherent cost of Silver Chloride material is offset against ease of manufacture.
| Transmission Range | 0.4 to 25 μm (1) |
| Refractive Index | 1.98 at 10 μm (1) |
| Reflection Loss | 19.5% at 10 μm (2 surfaces) |
| Absorption Coefficient | n/a |
| Reststrahlen Peak | 81.5 μm |
| dn/dT | -61 x 10-6 K-1 |
| dn/dμ | 4.5 μm |
| Density | 5.59 g/cc |
| Melting Point | 457°C |
| Thermal Conductivity | 1.15 W m-1 K-1 @ 278 K |
| Thermal Expansion | 31 x 10-6 K-1 @ 302 K |
| Hardness | Knoop 9.5 with 200g indenter |
| Specific Heat Capacity | 355 J Kg-1 K-1 |
| Dielectric Constant | 12.3 at 1 MHz |
| Young's Modulus (E) | 19.98 GPa |
| Shear Modulus (G) | 7.099 GPa |
| Bulk Modulus (K) | 44.04 GPa |
| Elastic Coefficients | C11 = 60.1; C12 = 36.2; C44 = 6.25 |
| Apparent Elastic Limit | 26.2 MPa (3800 psi) |
| Poisson Ratio | 0.4 |
| Solubility | 52 x 10-6 g/100 g water at 50°C |
| Molecular Weight | 143.34 |
| Class/Structure | Cubic FCC, NaCl, Fm3m, no cleavage, cold flows |
| μm | No | μm | No | μm | No |
|---|---|---|---|---|---|
| 0.5 | 2.09658 | 7.5 | 1.99021 | 15.0 | 1.95113 |
| 1.0 | 2.02239 | 8.0 | 1.98864 | 15.5 | 1.94743 |
| 1.5 | 2.01047 | 8.5 | 1.98661 | 16.0 | 1.94358 |
| 2.0 | 2.00615 | 9.0 | 1.98464 | 16.5 | 1.93958 |
| 2.5 | 2.00386 | 9.5 | 1.98255 | 17.0 | 1.9354 |
| 3.0 | 2.0023 | 10.0 | 1.98034 | 17.5 | 1.93109 |
| 3.5 | 2.00102 | 10.5 | 1.97801 | 18.0 | 1.9266 |
| 4.0 | 1.99983 | 11.0 | 1.97556 | 18.5 | 1.92194 |
| 4.5 | 1.99866 | 12.0 | 1.97026 | 19.0 | 1.91710 |
| 5.0 | 1.99745 | 12.5 | 1.96742 | 19.5 | 1.91208 |
| 5.5 | 1.99618 | 13.0 | 1.96444 | 20.0 | 1.90688 |
| 6.0 | 1.99483 | 13.5 | 1.96133 | 20.5 | 1.90149 |
| 6.5 | 1.99339 | 14.0 | 1.95807 | ||
| 7.0 | 1.99185 | 14.5 | 1.95467 |
Silver Chloride is grown into small ingots by the sealed-ampoule Stockbarger techniques. Silver chloride is malleable and milky-white it darkens in sunlight, but mild darkening does not affect the IR performance.
REFERENCES:
(1) Handbook of Optical Constants, ed Palik, V3, ISBN 0-12-544423-0