CsBr
CsBr is a soft, hygroscopic alkali halide crystal that transmits from 0.2 to 40 µm, supplied as IR single crystal (SC-IR), hot-pressed polycrystalline (POLY-HP) and europium-doped CsBr:Eu.
Reference datasheet — CsBr is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SC-IR condition
CsBr tempers and conditions
CsBr is supplied in 3 conditions, soft to hard. SC-IR is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Europium-doped storage-phosphor / scintillator grade | Pick the europium-doped grade for columnar needle-structure photostimulable storage screens in X-ray imaging plates; it is not intended for infrared transmitting windows. | 6 | 1.5 | 19 HV | 0.9 W/m·K | |
SC-IRDefault Bridgman-grown optical single crystal, IR window grade | Choose the Bridgman-grown single crystal for 0.2–40 µm far-infrared windows, prisms and beamsplitter substrates, and keep it in a dry environment during service. | 6 | 2 | 20 HV | 0.94 W/m·K | |
Hot-pressed / forged polycrystalline CsBr blank | Use the hot-pressed or forged polycrystalline blank when higher mechanical strength and larger apertures are needed and slight scattering can be tolerated. | 12 | 1 | 25 HV | 0.88 W/m·K |
What is CsBr?
CsBr is a soft, hygroscopic alkali halide crystal that transmits from 0.2 to 40 µm, supplied as IR single crystal (SC-IR), hot-pressed polycrystalline (POLY-HP) and europium-doped CsBr:Eu. It is specified for far-IR spectroscopy windows, prisms and FTIR optics where transmission must extend beyond the range of cheaper halides. Elastic modulus is only 15.8 GPa and machinability rates 55, so parts deform under modest clamping loads; service is limited to 300 °C and to dry, conditioned air because the surface fogs in humidity. KBr is the usual lower-cost substitute when the full 40 µm reach is not needed. CsBr has a density of 4.44 g/cm³ (0.16 lb/in³), heavier than 75% of glass grades. It melts at 636°C (1,177 °F). CsBr has a tensile strength of 6 MPa (0.87 ksi), weaker than 94% of glass grades. Elongation at break is 2% and the elastic modulus is 15.8 GPa (2.29 Msi).
What is CsBr used for?
- far-IR spectroscopy windows
- IR prisms
- FTIR components
Advantages
- Easy to machine — 55/100, better than 93% of glass grades
- Ductile — tolerates forming and impact — 2%, better than 84% of glass grades
Limitations
- Low fracture toughness — 0.1 MPa·√m (0.091 ksi·√in), worse than 100% of glass grades
- Low stiffness — 15.8 GPa (2.29 Msi), worse than 98% of glass grades
- Needs corrosion protection — 8/100, worse than 94% of glass grades
- Hard to polish — 55/100, worse than 85% of glass grades
- Poor heat conductor — 0.94 W/m·K (0.543 BTU/hr·ft·°F), worse than 81% of glass grades
CsBr properties
Typical room-temperature values for CsBr-SC-IR; bars are the position among glass grades.
Physical5
CsBr has a density of 4.44 g/cm³ (0.16 lb/in³), heavier than 75% of glass grades. It melts at 636°C (1,177 °F).
Mechanical13
CsBr has a tensile strength of 6 MPa (0.87 ksi), weaker than 94% of glass grades. Elongation at break is 2% and the elastic modulus is 15.8 GPa (2.29 Msi).
Thermal5
CsBr is rated for continuous service to 300°C (572 °F). It conducts heat at 0.94 W/m·K (0.543 BTU/hr·ft·°F), worse than 81% of glass grades. Thermal expansion is 47.9 µm/m·K (26.6 µin/in·°F).
Electrical3
CsBr has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (8/100), worse than 94% of glass grades.
Manufacturability2
CsBr's machinability is good (55/100, better than 93% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. CsBr is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CsBr
Is CsBr easy to machine?
Turn at low speed with sharp single-crystal diamond tools or cut dry with a wire saw; the crystal cleaves on {100}. Do not use water-based coolant, and dehumidify the machining enclosure.
Can CsBr be welded?
Not weldable; hold optics with mechanical retaining rings, dry-sealed O-rings or low-temperature optical cement.
Can CsBr be formed, bent or molded?
Blanks come from Bridgman–Stockbarger or Czochralski melt growth, or from hot-pressed/hot-forged polycrystalline billets. The material cannot be cold formed.
CsBr 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 |
|---|---|---|
| Csstoichiometric CsBr | 62.2 – 62.7 | 62.45 |
| Euonly in CsBr:Eu storage-phosphor variant | 0 – 0.5 | 0.1 |
| Br | ≥ 37.3 (balance) |
What surface finishes work on CsBr?
Polish with dry polishing powder carried in anhydrous ethanol or kerosene. Finished parts can be coated with KRS-5, Ge or polymer moisture barriers and must be stored in a desiccator at all times.
How much does CsBr cost?
CsBr is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
CsBr — frequently asked
What is CsBr used for?
CsBr is typically used for far-IR spectroscopy windows, IR prisms and FTIR components. In short: transmits to 40 µm; very soft, hygroscopic halide; doped storage-phosphor grade.
What is the tensile strength of CsBr?
CsBr has a typical tensile strength of 6 MPa (0.87 ksi) — weaker than 94% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is CsBr easy to machine?
Reasonably — machinability is rated good (55/100, better than 93% of glass grades). Turn at low speed with sharp single-crystal diamond tools or cut dry with a wire saw; the crystal cleaves on {100}. Do not use water-based coolant, and dehumidify the machining enclosure.
Can CsBr be welded?
Not weldable; hold optics with mechanical retaining rings, dry-sealed O-rings or low-temperature optical cement.
What surface finishes work on CsBr?
Polish with dry polishing powder carried in anhydrous ethanol or kerosene. Finished parts can be coated with KRS-5, Ge or polymer moisture barriers and must be stored in a desiccator at all times.
Can CsBr be formed, bent or molded?
Blanks come from Bridgman–Stockbarger or Czochralski melt growth, or from hot-pressed/hot-forged polycrystalline billets. The material cannot be cold formed.
What is the maximum service temperature of CsBr?
CsBr is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does CsBr cost?
CsBr is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Handbook of Optical Materials — CRC Press (Weber) (2003)
- CRC Handbook of Chemistry and Physics — CRC Press (2020)
- CsBr IR window / crystal datasheet — Korth Kristalle GmbH (2022)
- Refractive index and dispersion of alkali halides — J. Phys. Chem. Ref. Data (1976)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.