LiF HF-POLY
Grade
HF-POLY = 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.
Values for the HF-POLY 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 |
|---|---|---|---|---|---|---|
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 |
HF-POLYThis page 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 HF-POLY?
LiF HF-POLY is LiF in the HF-POLY grade — choose when large-aperture IR windows with better mechanical strength and no cleavage planes are needed; scatters slightly and is not VUV-grade. The elastic modulus is 67 GPa (9.72 Msi). LiF HF-POLY 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
- Easy to machine — 35/100, better than 77% of glass grades
Limitations
- Needs corrosion protection — 35/100, worse than 88% of glass grades
- Hard to polish — 50/100, worse than 88% of glass grades
- Low fracture toughness — 0.5 MPa·√m (0.455 ksi·√in), worse than 76% of glass grades
- High embodied carbon — 18 kg CO₂/kg, worse than 76% of glass grades
LiF HF-POLY properties
Typical room-temperature values for LiF HF-POLY; 10 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 HF-POLY 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 67 GPa (9.72 Msi).
Thermal5
LiF HF-POLY is rated for continuous service to 350°C (662 °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 HF-POLY 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 HF-POLY 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 HF-POLY's machinability is fair (35/100, better than 77% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with LiF HF-POLY
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 HF-POLY — frequently asked
What is LiF HF-POLY used for?
LiF HF-POLY 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 HF-POLY easy to machine?
Not especially — machinability is rated fair (35/100, better than 77% 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 HF-POLY 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 HF-POLY?
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 HF-POLY 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 HF-POLY?
LiF HF-POLY is rated for continuous use to about 350°C (662 °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.