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Caesium Bromide CsBr
Cesium Bromide has limited application in the deep IR. Cesium Bromide is slightly more amenable to optical working than CsI and is sometimes used as a beamsplitter component in wide-band spectrophotometers.
| Transmission Range | 0.25 to 40 μm (1) |
| Refractive Index | 1.6612 at 11 μm (1) |
| Reflection Loss | 11.6% at 11 μm (2 surfaces) |
| Absorption Coefficient | n/a |
| Reststrahlen Peak | 121.2 μm (2) |
| dn/dT | -84 x 10⁻⁶ K⁻¹ at 0.6 μm (5) |
| dn/dμ | 5.3 μm |
| Density | 4.44 g/cc |
| Melting Point | 636 °C |
| Thermal Conductivity | 0.94 W m⁻¹ K⁻¹ at 273K |
| Thermal Expansion | 47.9 x 10⁻⁶ K⁻¹ at 273K |
| Hardness | Knoop 19.5 with 200g indenter |
| Specific Heat Capacity | 263.8 J Kg⁻¹ K⁻¹ (3) |
| Dielectric Constant | 6.51 at 2 MHz |
| Youngs Modulus (E) | 15.85 GPa (4) |
| Shear Modulus (G) | 7.5 GPa |
| Bulk Modulus (K) | 13.01 GPa |
| Elastic Coefficients | C11=30.97; C12=4.03; C44=7.5 |
| Apparent Elastic Limit | 8.4 MPa (1220 psi) (4) |
| Poisson Ratio | 0.279 |
| Solubility | 90g/100ml water at 25°C (See Graph) (6) |
| Molecular Weight | 212.83 |
| Class/Structure | Cubic CsCl, Pm3m, no cleavage planes |
| μm | No | μm | No | μm | No |
|---|---|---|---|---|---|
| 0.5 | 1.70896 | 15.0 | 1.65468 | 30.0 | 1.60947 |
| 1.0 | 1.67793 | 16.0 | 1.65272 | 31.0 | 1.6051 |
| 2.0 | 1.67061 | 17.0 | 1.65062 | 32.0 | 1.60053 |
| 3.0 | 1.66901 | 18.0 | 1.64838 | 33.0 | 1.59576 |
| 4.0 | 1.66813 | 19.0 | 1.646 | 34.0 | 1.59078 |
| 5.0 | 1.66737 | 20.0 | 1.64348 | 35.0 | 1.58558 |
| 6.0 | 1.66659 | 21.0 | 1.6408 | 36.0 | 1.58016 |
| 7.0 | 1.66573 | 22.0 | 1.63798 | 37.0 | 1.5745 |
| 8.0 | 1.6477 | 23.0 | 1.635 | 38.0 | 1.5686 |
| 9.0 | 1.6637 | 25.0 | 1.62856 | 39.0 | 1.56245 |
| 10.0 | 1.66251 | 26.0 | 1.62509 | ||
| 11.0 | 1.6612 | 27.0 | 1.62146 | ||
| 12.0 | 1.65976 | 28.0 | 1.61764 | ||
| 13.0 | 1.6582 | 29.0 | 1.61365 | ||
| 14.0 | 1.6561 |
Caesium Bromide is grown by sealed ampoule Stockbarger technique. CsBr is a soft pliable material.
IUPAC International Union of Pure and applied Chemistry recommends the spelling as Cesium. UK Useage is Caesium.
Solubility has historically been quoted as 124g/100mL at 25°C but Crystran Ltd tests 2021 have found this to be inaccurate.
REFERENCES:
(1) Handbook Optical Constants, ed Palik, V3, ISBN 0-12-544423-0
(2) Mitsuishi et al., J Opt Soc. Am. V52, p14, 1962
(3) Kelly, Bureau of Mines Bulletin, No371, p51, 1934
(4) S.Ballard et al; J.Opt.Soc.Am. Vol42, p684, 1952
(5) H.H.Li; J.Phys. Chem. Ref. Data. Vol 5, No 2. 1976
(6) K.Matthews. Crystran Ltd Test Data 2021
