LiF IR
Grade
IR = standard optical / IR grade single crystal
Lower-cost boule material for 0.2–6 µm windows, prisms and X-ray analyser plates where deep-VUV transmission is not required.
Values for the IR condition
Other LiF tempers and conditions
LiF is listed in 3 conditions; see the grade overview at LiF.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
IRThis page Standard optical / IR grade single crystal | Lower-cost boule material for 0.2–6 µm windows, prisms and X-ray analyser plates where deep-VUV transmission is not required. | — | 11 | 0 | 105 HV | 11 W/m·K |
LiF:Mg,Ti dosimeter grade | Doped, tissue-equivalent LiF chips/rods for thermoluminescent radiation dosimetry rather than for imaging optics. | — | 12 | 0 | 110 HV | 11 W/m·K |
Hot-forged / press-forged polycrystalline LiF | Choose when large-aperture IR windows with better mechanical strength and no cleavage planes are needed; scatters slightly and is not VUV-grade. | — | — | — | 120 HV | — |
What is LiF IR?
LiF IR is LiF in the IR grade — lower-cost boule material for 0.2–6 µm windows, prisms and X-ray analyser plates where deep-VUV transmission is not required. The elastic modulus is 64.8 GPa (9.4 Msi). LiF IR has a density of 2.64 g/cm³ (0.0953 lb/in³), lighter than 54% of glass grades. It melts at 848°C (1,558 °F).
Advantages
- Conducts heat well — 11.3 W/m·K (6.53 BTU/hr·ft·°F), better than 81% of glass grades
Limitations
- Needs corrosion protection — 35/100, worse than 88% of glass grades
- Hard to polish — 60/100, worse than 81% of glass grades
- Low fracture toughness — 0.35 MPa·√m (0.319 ksi·√in), worse than 79% of glass grades
- High embodied carbon — 18 kg CO₂/kg, worse than 76% of glass grades
LiF IR properties
Typical room-temperature values for LiF IR; 14 are specific to this condition. Other listed values are LiF reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
LiF IR has a density of 2.64 g/cm³ (0.0953 lb/in³), lighter than 54% of glass grades. It melts at 848°C (1,558 °F).
Mechanical9
The elastic modulus is 64.8 GPa (9.4 Msi).
Thermal5
LiF IR is rated for continuous service to 400°C (752 °F). It conducts heat at 11.3 W/m·K (6.53 BTU/hr·ft·°F), better than 81% of glass grades. Thermal expansion is 37 µm/m·K (20.6 µin/in·°F).
Electrical3
LiF IR has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (35/100), worse than 88% of glass grades.
Sustainability3
Producing a kilogram of LiF IR takes about 250 MJ of energy and emits 18 kg of CO₂ — more than 76% of glass grades. Typical recycled content is 0%.
Manufacturability2
LiF IR's machinability is poor (28/100, better than 66% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with LiF IR
Is LiF easy to machine?
Saw with diamond wire/blade using oil or kerosene coolant; cleaves readily on {100} so avoid impact and clamping stress; single-point diamond turning works well at low feed.
Can LiF be welded?
Not weldable — components are grown, cleaved, sawn and cemented; use low-stress epoxy or spring mounts, never solder or braze.
Can LiF be formed, bent or molded?
Shaped by Czochralski/Kyropoulos/Bridgman growth or by hot press-forging of sintered blanks near 700–800 °C; anneal slowly (high CTE) to avoid stress birefringence and cracking.
What surface finishes work on LiF?
Polish with non-aqueous slurries (ethylene glycol/alcohol-based) on pitch or cloth; AR coat and store desiccated, since humid air fogs the surface.
LiF chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Linatural isotopic abundance unless 6Li/7Li enriched grade is specified | 26.5 – 26.9 | 26.75 |
| metallic impurities (total)optical grade, typically <50 ppm; OH/oxide content controls VUV cutoff | 0 – 0.01 | 0.01 |
| F | balance | — |
LiF IR — frequently asked
What is LiF IR used for?
LiF IR is typically used for VUV windows and monochromators, spectroscopy prisms and thermoluminescent dosimetry. In short: shortest UV cutoff crystal; vacuum-UV window material; dosimetry-grade option available.
Is LiF IR easy to machine?
Not especially — machinability is rated poor (28/100, better than 66% of glass grades). Saw with diamond wire/blade using oil or kerosene coolant; cleaves readily on {100} so avoid impact and clamping stress; single-point diamond turning works well at low feed.
Can LiF IR be welded?
Not weldable — components are grown, cleaved, sawn and cemented; use low-stress epoxy or spring mounts, never solder or braze.
What surface finishes work on LiF IR?
Polish with non-aqueous slurries (ethylene glycol/alcohol-based) on pitch or cloth; AR coat and store desiccated, since humid air fogs the surface.
Can LiF IR be formed, bent or molded?
Shaped by Czochralski/Kyropoulos/Bridgman growth or by hot press-forging of sintered blanks near 700–800 °C; anneal slowly (high CTE) to avoid stress birefringence and cracking.
What is the maximum service temperature of LiF IR?
LiF IR is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Lithium Fluoride (LiF) optical material datasheet — Crystran Ltd (2023)
- LiF single crystal properties — Korth Kristalle GmbH (2022)
- Handbook of Optical Constants of Solids — Academic Press (Palik, ed.) (1998)
- CRC Handbook of Chemistry and Physics, 104th ed. — CRC Press (2023)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.