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Silver Bromide AgBr
Silver Bromide is useful material for very deep IR applications where sensitivity to moisture is a problem. Silver Bromide crystal growth was developed relatively recently by the standards of many IR materials. The parameters of Silver Bromide have not been researched as thoroughly as those of Silver Chloride. This soft crystal deforms under heat and pressure and can be forged in polished dies to create IR windows and lenses.
| Transmission Range | 0.5 to 35 μm (1) |
| Refractive Index | 2.167 at 10 μm (1) (2) |
| Reflection Loss | 23.9% at 10 μm (2 surfaces) |
| Absorption Coefficient | n/a |
| Reststrahlen Peak | 112.7 μm |
| dn/dT | n/a |
| dn/dμ | n/a |
| Density | 6.473 g/cc |
| Melting Point | 432°C |
| Thermal Conductivity | 1.21 W m-1 K-1 @ 273 K |
| Thermal Expansion | 30 x 10-6/°C @ 273 K |
| Hardness | Knoop 7 |
| Specific Heat Capacity | 292 J Kg-1 K-1 |
| Dielectric Constant | 13.1 at 1 MHz (2) |
| Young's Modulus (E) | 31.97 GPa |
| Shear Modulus (G) | n/a |
| Bulk Modulus (K) | 44.03 GPa |
| Elastic Coefficients | C11 = 56.3; C12 = 32.3; C44 = 7.25 |
| Apparent Elastic Limit | 30.3 MPa (4400 psi) |
| Poisson Ratio | n/a |
| Solubility | 12 x 10-6 g/100 g water at 20°C |
| Molecular Weight | 187.78 |
| Class/Structure | Cubic FCC, NaCl, Fm3m, no cleavage, cold flows |
| μm | No | μm | No | μm | No |
|---|---|---|---|---|---|
| 0.391 | 2.416 | 0.60 | 2.25 | 9.926 | 2.167 |
| 0.477 | 2.330 | 0.65 | 2.24 | 12.66 | 2.162 |
| 0.496 | 2.313 | 0.781 | 2.205 | ||
| 0.550 | 2.270 |
Silver Bromide is grown in small ingots by sealed ampoule Stockbarger techniques. Silver Bromide is malleable and deep yellow, it darkens in sunlight, but less readiliy than Silver Chloride.
(1) Handbook of Optical Constants, ed Palik, V3, ISBN 0-12-544423-0
(2) White; Optical Properties of Silver Bromide. J.Opt.Soc. Am. V62, N2 (1973)