Material

Refractive Index
n

Hardness
(Knoop)
psi

Modulus of Rupture*
psi

Useful Transmission Range

Chemical Properties

Windows (1-2mm)
cm-1
micrometers

IREs (70mm)
cm-1
micrometers

BK-7 Glass

1.50

520

2400

31,000-4300
0.32-2.3

29,000-5000
0.34-1.97

Insoluble in water

UV Quartz
UV SiO2

1.44

461

7100

57,000-3000
0.175-3.4

50,000-4000
0.2-2.5

Insoluble in water；soluble in HF

UV Sapphire
Al2O3

1.75

1370

65000

66,000-2000
0.15-5.0

33,000-2800
0.3-3.7

Very slightly soluble in acids and bases

Strontium Titinate
SrTiO3

2.41

595

7500

25,000-1700
0.395-6

25,000-2500
0.4-4

Readily attacked by HF；resistant to most solvents

Lithium Fluoride
LiF

1.33

110

2000

90,000-1,500
0.11-7.0

50,000-2300
0.2-4.5

Slightly soluble in water；soluble in HF

Titanium Dioxide
TiO2

2.6；2.9

800

700

24,000-1700
0.42-6

20,000-2200
0.5-4.5

Soluble in H2SO4 and alkalis；insoluble in water and acids

Zirconium Dioxide
ZrO2

2.15

1250

7800

27,000-1,500
0.36-7

25,000-1800
0.4-5.5

Insoluble in water；soluble in HF and H2SO4

Magnesium Oxide
MgO

1.68

640

19000

25,000-1300
0.15-8.0

20,000-1700
0.5-6.0

Soluble in acids and NH4 salts

Silicon
Si

3.42

1150

9000

10,000-100
1.0-100

9500-1500；350-FIR
1.06-6.7；30-FIR

Insoluble in most acids and bases；soluble in HF and HNO3

Calcium Fluoride
CaF2

1.4

158

5300

66,000-1300
0.15-8.0

33,000-1500
0.3-7.0

Insoluble in water；resists most acids and bases；soluble in NH4 salts

Arsenic Trisulfide
As2S3

2.4

109

2400

14,000-1200
0.7-9.0

12,500-1300
0.8-8.2

Soluble in alcohols and alkalis；slightly soluble in water

Strontium Fluoride
SrF2

1.44

1405

500

66,000-1000
0.15-11

33,000-1100
0.3-9.5

Very slightly soluble in water；soluble in hot HCl

Barium Fluoride
BaF2

1.45

82

3900

50,000-1000
0.2-11

33,000-1100
0.3-9.5

Low water solubility；soluble in acids and NH4Cl

Zinc Sulfide
ZnS

2.22

355

10000

22,000-750
0.45-14.0

14,000-1000
0.7-10

Soluble in acids；insoluble in water

Germanium
Ge

4.0

550

7000

5000-600
2.0-17

5000-900
2.0-11.4

Insoluble in water；soluble in hot H2SO4 and aqua regia.

Arsenic Triselenide
As2Se3

2.8

90

500

12,500-600
0.8-17

11,000-900
0.9-11.8

Insoluble in bases

Sodium Chloride
NaCl

1.5

15

350+

28,000-700
0.35-15

25,000-900
0.4-12

Hygroscopic；slightly soluble in alcohols and NH3

AMTIR
(GeAsSe Glass)

2.5

170

2700

11,000-1000
0.99-11

11,000-1100
0.9-9.5

Insoluble in water

Gallium Arsenide
GaAs

3.14

750

11000

10,000-600
1-17

10,000-700
1-14

Insoluble in water；slightly soluble in acids and bases

Zinc Selenide
ZnSe

2.42

150

8000

20,000-500
0.5-20

20,000-700
0.5-14.3

Soluble in strong acids；dissolves in HNO3

Potassium Chloride
KCl

1.47

7

330+

33,000-500
0.3-20

20,000-700
0.5-15

Hygroscopic；water soluble；slightly soluble in alcohols

Silver Chloride
AgCl

2.00

10

3800+

23,000-400
0.42-27

22,000-700
0.45-16

Insoluble in water；soluble in NH4OH

Potassium Bromide
KBr

1.52

7

160+

33,000-400
0.3-25

20,000-500
0.5-20

Soluble in water, alcohols and glycerine；hygroscopic

Silver Bromide
AgBr

2.2

10

500+

20,000-300
0.5-35

20,000-500
0.5-22

Insoluble in water and alcohols；slightly soluble in NH4OH

Cadmium Telluride
CdTe

2.65

45

850

10,000-350
1.0-28

10,000-500
1.0-22

Insoluble in water and acid

Cestium Bromide
CsBr

1.65

20

1220+

33,000-250
0.3-40

25,000-400
0.4-27

Soluble in water and acids；hygroscopic

Cesium OIodide
CsI

1.72

20

810

33,000-150
0.3-70

20,000-400
0.5-30

Soluble in water and alcohol；hygroscopic

Thallium Bromoiodide
KRS-5

2.35

40

3800+

16,000-200
0.6-60

14,000-400
0.7-30

Soluble in warm water；soluble in bases；insoluble in acids

Crystal Quartz
SiO2

1.5

741

1500

50,000-3600；250-30
0.2-2.8；40-333

250-FIR
40-FIR

Soluble in HF；insoluble in water

Polyethylene
[PE] (high density)

1.55

5

400+

600-10
16-1000

600-FIR
16-FIR

Resistant to most solvents

Diamond
C

2.4

7000

54400

45,000-2500；1600-FIR
6-FIR**

Insoluble in water, acids and bases