Germanium crystal growth
Ge

Crystal properties

Crystal Type:

cubic, diamond structure

 

Transmission Range

1.8 ... 23 µm

 

Refractive Index

4.0034 @ 9.72 µm, 
4.0028 @ 10.6 µm

 

Reflective Loss

52.9 % @ 10 µm

 

Density

5.323 g/cm3

 

Melting Point

956, 959, 942, 938 °C

 

Molecular Weight

72.59

 

Thermal Conductivity

58.61 W/(m K)

 

Specific Heat

310 J/(kg K) @ 25 °C

 

Thermal Expansion

5.5×10–6 / K, 6.1×10–6 / K

 

Hardness (Knoop)

780

 

Young’s Modulus

102.7 <100>, 155.3 <111> GPa

Shear Modulus

67 <100> GPa

Bulk Modulus

77.2 GPa

Rupture Modulus

93 MPa

Elastic Coefficient:

C11 = 129 / C12 = 48.3 / C44 = 67.1 GPa

Dielectric Constant

16.6 @ f = 9.37 GHz

Solubility in Water

Insoluble

Application

Electronics lenses, band pass filters, thermography

Remarks

laser damage threshold: 2.9 ...3.3 GW / cm2

Germanium substrates

 

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