Lithium Fluoride
LiF

Crystal properties

Crystal Type

cubic, NaCl type structure

Transmission Range

0.12 ... 9 µm

Refractive Index

1.37327 @ 2,5 µm

Reflective Loss

4.4 % @ 4.0 µm

Reststrahlen

25 µm

Density

2.63905 g/cm3

Melting Point

870; 848 °C

Molecular Weight

25.9394

Thermal Conductivity

4.01 W/(m K)

Specific Heat

1562 J/(kg K)

Thermal Expansion

37 × 10–6 / K @ 0...100 °C

Hardness (Knoop)

102 – 103 (indenter load: 600 g)

Young’s Modulus

64.79 GPa

Shear Modulus

55.14 GPa

Bulk Modulus

62.03 GPa

Rupture Modulus

10.8 MPa

Elastic Coefficient

C11 = 112
C12 = 45.6
C44 = 3.2 GPa

Dielectric Constant

9.0 @ 25 °C, f = 100...109 Hz

Solubility in Water

0.28 g / 100 g @ 18 °C

Crystal Structure

Single crystal, synthetic

Cleavage Planes

(100)

Standard Diameter

145 mm, 200 mm

Application

X-ray monochromator plates 
optical material for DUV applications

Remarks

tends to create colour centers

 

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