CaF2 IR (IR-grade single crystal)
Grade
also Irtran-3
Use the lower-cost infrared blank for FTIR windows and IR lenses working from 0.25 to 9 µm, accepting uncontrolled absorption and fluorescence at the UV end.
Values for the IR condition
Other CaF2 tempers and conditions
CaF2 is listed in 3 conditions; see the grade overview at CaF2.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
VUV/Excimer | Choose the lithography and excimer-laser grade when transmission from 0.13 µm, very low fluorescence and stress birefringence, and resistance to radiation-induced colour centres are required. | — | 37 | 0 | 165 HV | 10 W/m·K |
IRThis page IR-grade single crystal | Use the lower-cost infrared blank for FTIR windows and IR lenses working from 0.25 to 9 µm, accepting uncontrolled absorption and fluorescence at the UV end. | — | 37 | 0 | 165 HV | 10 W/m·K |
Poly | Pick the hot-pressed polycrystal for large domes needing higher strength and thermal-shock resistance than single crystal; grain-boundary scatter lowers UV and long-wave transmission. | — | — | — | 205 HV | — |
What is CaF2 IR?
CaF2 IR is CaF2 in the IR grade — use the lower-cost infrared blank for FTIR windows and IR lenses working from 0.25 to 9 µm, accepting uncontrolled absorption and fluorescence at the UV end. CaF2 IR has a tensile strength of 37 MPa (5.37 ksi), weaker than 70% of glass grades. The elastic modulus is 75.8 GPa (11 Msi). CaF2 IR has a density of 3.18 g/cm³ (0.115 lb/in³), heavier than 58% of glass grades. It melts at 1,418°C (2,584 °F).
Advantages
- Easy to machine — 45/100, better than 85% of glass grades
- High service temperature — 800°C (1,472 °F), better than 81% of glass grades
- Conducts heat well — 9.7 W/m·K (5.6 BTU/hr·ft·°F), better than 78% of glass grades
Limitations
- Hard to polish — 55/100, worse than 85% of glass grades
- Needs corrosion protection — 45/100, worse than 84% of glass grades
- Low fracture toughness — 0.33 MPa·√m (0.3 ksi·√in), worse than 81% of glass grades
CaF2 IR properties
Typical room-temperature values for CaF2 IR; 15 are specific to this condition. Other listed values are CaF2 reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
CaF2 IR has a density of 3.18 g/cm³ (0.115 lb/in³), heavier than 58% of glass grades. It melts at 1,418°C (2,584 °F).
Mechanical10
CaF2 IR has a tensile strength of 37 MPa (5.37 ksi), weaker than 70% of glass grades. The elastic modulus is 75.8 GPa (11 Msi).
Thermal5
CaF2 IR is rated for continuous service to 800°C (1,472 °F). It conducts heat at 9.7 W/m·K (5.6 BTU/hr·ft·°F), better than 78% of glass grades. Thermal expansion is 18.9 µm/m·K (10.5 µin/in·°F).
Electrical3
CaF2 IR has an electrical resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (45/100), worse than 84% of glass grades.
Manufacturability2
CaF2 IR's machinability is fair (45/100, better than 85% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CaF2 IR
Is CaF2 easy to machine?
Grind with diamond wheels at low contact pressure or finish by single-point diamond turning, keeping loads light to avoid edge chipping along the {111} cleavage planes. Use anhydrous oil-based coolant only; water-based fluids are not permitted.
Can CaF2 be welded?
Not weldable; mount with elastomeric retaining rings, low-stress cementing or optical contact, since assembly stress induces birefringence.
Can CaF2 be formed, bent or molded?
Boules are grown in vacuum from high-purity CaF₂ powder with an oxygen scavenger by the Bridgman–Stockbarger crucible-descent method and then annealed to relieve stress. Polycrystalline parts are produced by hot pressing.
What surface finishes work on CaF2?
Rough-grind first, then polish on pitch laps with cerium oxide or alumina. Finish with an MgF₂ or multilayer UV/IR anti-reflection coating to raise transmission and protect against moisture.
CaF2 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 |
|---|---|---|
| Castoichiometric CaF2 | 51 – 51.4 | 51.33 |
| Fmetals <50 ppm; UV/excimer grade: O, Ce, Na, K <1-5 ppm | ≥ 48.6 (balance) | — |
CaF2 IR — frequently asked
What is CaF2 IR used for?
CaF2 IR is typically used for UV lithography lenses, excimer laser optics, spectroscopic windows and IR windows. In short: broadest UV-IR transmission; lowest dispersion fluoride crystal; standard 193 nm optic.
What is the tensile strength of CaF2 IR?
CaF2 IR has a typical tensile strength of 37 MPa (5.37 ksi) — weaker than 70% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is CaF2 IR easy to machine?
Reasonably — machinability is rated fair (45/100, better than 85% of glass grades). Grind with diamond wheels at low contact pressure or finish by single-point diamond turning, keeping loads light to avoid edge chipping along the {111} cleavage planes. Use anhydrous oil-based coolant only; water-based fluids are not permitted.
Can CaF2 IR be welded?
Not weldable; mount with elastomeric retaining rings, low-stress cementing or optical contact, since assembly stress induces birefringence.
What surface finishes work on CaF2 IR?
Rough-grind first, then polish on pitch laps with cerium oxide or alumina. Finish with an MgF₂ or multilayer UV/IR anti-reflection coating to raise transmission and protect against moisture.
Can CaF2 IR be formed, bent or molded?
Boules are grown in vacuum from high-purity CaF₂ powder with an oxygen scavenger by the Bridgman–Stockbarger crucible-descent method and then annealed to relieve stress. Polycrystalline parts are produced by hot pressing.
What is the maximum service temperature of CaF2 IR?
CaF2 IR is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Calcium Fluoride (CaF2) optical material datasheet — Crystran Ltd (2023)
- Engineered Materials Handbook Vol.4 — Ceramics and Glasses — ASM International (1991)
- Handbook of Optical Constants of Solids — Academic Press (Palik ed.) (1998)
- Calcium Fluoride for excimer laser and lithography optics — Corning Advanced Optics / Hellma Materials (2022)
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.