Thalliumbromidiodid (KRS-5)

Material
KRS-5

 

Thallium bromoiodide is a deep IR material with a high refractive index. KRS-5 crystalizes by the sealed-ampoule Stockbarger technique. Starting materials of the highest purity are selected to ensure that there are no anionic absorption bands between 2 and 16 microns and all crystals are checked for quality by using a path length of 120mm.

 

KRS-5 is only slightly soluble in water but can be dissolved in alcohol and nitric acid. This material is considered toxic and should be handled with care. The refractive index of KRS-5 can vary due to small compositional changes and can sometimes be a gradient across the material.

 

KRS-5 is used extensively in spectroscopy for ATR (Attenuated Total Reflection) prisms, windows and lenses. The low solubility, high refractive index and low absorption makes KRS-5 ideal for this application. In conjunction with Germanium, KRS-5 can also be used in athermalised IR imaging systems.

 

Properties
Optical properties
Transmission range in µm (minimum 10%)
0,57‐40
Transmission range in µm (minimum 50%)
0,56‐40
Refractive index @633nm
2,573

(2,371 @10,6µm)

Reflection losses in % at 1 surface
16,53 @10µm
Reflection losses in % at 2 surfaces
28,4 @10µm
dN/dT in 1/K
-235 · 10-6
Physical properties
Density in g/cm3
7,365
Melting point in °C
414,5
Spezific heat capacity in J/(kg · K)
160
Thermal conductivity in W/(m · K)
0,544 @293K
Thermal expension in 1/K
58 · 10-6 @293‐373
Dielectric constants
32,5
Solubility in water in g/100g
0,05
Mohs hardness
Knoop hardness in kg/mm²
40,2 <100>
Material type
single crystalline, synthetic
Crystal type
cubic, CsCl structure
Crystal structure
F43m
Lattice constant in Å
a = 4,11
Elastic coefficient in GPa
C11 = 34,1

C12 = 13,6

C44 = 5,79

Young's Modulus (E) in Gpa
15,85
Shear Modulus (G) in GPa
5,79
Bulk Modulus (K) in GPa
19,78
Rupture Modulus in MPa
26,2
Apparent elastic limit in MPa
26,2
Poisson ratio
0,34
Spectral properties
Optical Properties
Transmission range in µm @10% min. 0.56 - 40
Transmission range in µm @50% min. 0.57 - 40
Refractive index @633nm 2.57288
(2.371 @10.6µm)
Reflection losses in % at 1 surface 16.53 @10µm
Reflection losses in % at 2 surfaces 28.4 @10µm
dn/dT in 1/K -235· 10-6
Physical Properties
Density in g/cm³ 7.365
Melting point in °C 414.5
Specific heat capacity in J/(kg · K) 160
Thermal Conductivity in W/(m · K) 0.544 @293K
Thermal Expansion in 1/K 58 · 10-6 @293-373K
Dielectric constant 32.5
Solubility in water in g/100g 0.05
Mohs hardness
Knoop hardness in kg/mm² 40.2 <100>
Material type Single crystal, synthetic
Crystal type cubic, CsCl structure
Crystal structure Pm3m
Lattice constant in Å a = 4.11
Elastic coeficients in GPa C11 = 34.1
C12 = 13.6
C44 = 5.79
Young's Modulus (E) in GPa 15.85
Shear Modulus (G) in GPa 5.79
Bulk Modulus (K) in GPa 19.78
Rupture Modulus in MPa 26.2
Apparent elastic limit in MPa 26.2
Poisson ratio 0.34
Spectral Properties