LiF
crystals shows
excellent transmittance in the VUV region. It is used for windows, prisms,
and lenses in the visible and infrared in 0.104 μm - 7 μm. LiF
crystalis sensitive to thermal shock and would be attacked by atmospheric
moisture at 400�C. In addition irradiation produces color centers. Modest
precautions should be taken against moisture and high energy radiation
damage. Besides LiF is softens at 600�C and is slightly plastic that can
be bent into radius plates. The material can be cleaved along (100) and
less commonly (110). Although the optical characteristics are good the
structure is not perfect and cleavage is difficult. For good structure LiF
is less commonly grown by the Kyropoulos method (air-grown) specifically
for monochromator plates. High quality LiF is usually grown by modified
Bridgman technique. Maximum available size in diameters is 115mm. LiF is
slightly plastic and can be bent into radius plates.
Material and
Specifications:
|
|
Transmission
Range (�m)
|
0.12
~ 6
|
Refractive
Index at 0.6 �m
|
1.39181
|
Reflection
Loss at 0.6 �m
|
5.2%
(2 surfaces)
|
Absorption
Coefficient at 2.7�m (cm-1)
|
0.74�10-3
|
Density
(g/cm3)
|
2.639
|
Melting
Point (�C)
|
870
|
Thermal
Conductivity at 314K (Wm-1K-1)
|
4.01
|
Thermal
Expansion at 283K (K-1)
|
37�10-6
|
Knoop
Hardness
|
102
with 600g indenter
|
Specific
Heat Capacity (J Kgm-1K-1)
|
1562
|
Elastic
Coefficient
|
C11=112;
C12=46; C44= 63.5
|
Apparent
Elastic Limit
|
11.2
Mpa (1620 psi)
|
Poisson
Ratio
|
0.326
|
Solubility
in 100g water at 20�C
(g)
|
0.27
|
Cleavage
|
(100)
|
|
|