Potassium bromide
KBr
Potassium Bromide

Crystal properties

Crystal Type

cubic, NaCl  type structure 

 

Transmission Range

0.23 ... 25 µm 

Refractive Index

1.52695 @ 9.724 µm 

Reflective Loss

8.4 % @ 10.0 µm 

Reststrahlen

77.6 µm 

Density

2.7533 g/cm3 

Melting Point

730 °C 

Molecular Weight

119.002 

Thermal Conductivity

4.816 W/(m K) @ 46 °C 

Specific Heat

435 J/(kg K) @ 0 °C 

Thermal Expansion.

43 × 10–6 / K 

Hardness (Knoop)

5.9 <110> 
7.0 <100> 
Indenter load 200 g
 

Young’s Modulus

26.8 GPa 

Shear Modulus

5.08 GPa 

Bulk Modulus

15.03 GPa 

Rupture Modulus

0.33 MPa 

Elastic Coefficient 

C11 = 34.5 
 C12 = 5.4  
C44 = 5.08 GPa
 

Dielectric Constant

5.65 @ 25 °C, f = 100 Hz ... 10 GHz 

Solubility in Water

53.4 g / 100 g @ 0 °C 

Crystal Structure

Single crystal,  synthetic 

Cleavage Planes

(100) 

Standard Diameter

180 mm 

Application

IR spectroscopy
FTIR beamsplitters
CO2 laser optics
protective windows

Remarks

coatings available 

List of Optical Crystals

Materials

Refractive Index

Transmission
Range (mm)

Density
(g/cm³)

Thermal Expansion  
Coefficient (10
-6/K) 

 

BK7 glass

1.5164 (588 nm)

0.330 – 2.1

2.51

7.5 

 

SF11 glass

1.78472 (588 nm)

0.370 – 2.5

4.74

6.8 

 

F2 glass

1.62004 (588 nm)

0.420 – 2.0

3.61

8.2 

 

Fused Silica

1.4858 (308 nm)

0.185 – 2.5

2.20

0.55 

 

CaF2

1.399  (5.0 mm)

 0.170 – 7.8

3.18

 18.85 

 

BaF2

 1.460 (3.0 um)

 0.15 – 12.0

4.88

 18.4 

 

Sapphire

1.755 (1.0mm)

0.180 – 4.5

3.98

8.4 

 

Silicon

3.4179 (10mm)

 1.200 – 7.0

2.33

 4.15 

 

Ge

4.003 (10 mm)

 1.900 – 16

5.33

 6.1 

 

ZnSe

2.40  (10 mm)

0.630 – 18

5.27

7.8 

 

ZnS

2.2 (10mm)

0.380 –14

4.09

6.5 

 

LiF

1.39 (500 nm)

 0.150 – 5.2

2.64

37 

 

KBr

1.526 (10 mm)

 0.280 – 22

2.75

43 

 

 MgF2

no =  1.3836  ne = 1.3957 (405 nm)

0.130 – 7.0

7.37

a: 13.7         b: 8.48 

 

YVO4

no = 1.9500  ne = 2.1554 (1.3 mm)

0.400 – 5.0

4.22

a: 4.46       b: 11.37 

 

Calcite

no =  1.6557  ne = 1.4852 (633 nm)

0.210 – 2.3

2.75

a: 24.39        b: 5.68 

 

Quartz

no =  1.5427  ne = 1.5518 (633 nm)

0.200 – 2.3

2.65

7.07 

 

α-BBO

no =  1.6749  n= 1.5555 (532 nm)

0.190 – 3.5

3.85

a: 4.0           c: 36 

 

LiNbO3

 no =  2.2863  ne = 2.2027 (633 nm)

0.370 – 4.5

4.64

a: 16.7          c: 2.0