Potassium bromide ( KBr )

Crystal  properties

 

Potassium

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
ne = 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