ZERODUR (lithium aluminium silicon oxide glass-ceramic) ZERODUR
Lithium aluminium silicon oxide glass-ceramic, with nanocrystals in a residual glass phase (no single formula
Also known as ZERODUR
ZERODUR is a lithium aluminium silicon oxide glass-ceramic made by SCHOTT at Mainz, Germany.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Thermal expansion
0.007 ppm/K
Heat conduction
1.46 W/(m·K)
Hardness and modulus
620 HK 0.1/20
Optical quality
1.5424 nd
Recipe, share of the weight
- Li2O not statedLithium oxide
- Al2O3 not statedAluminium oxide
- SiO2 not statedSilicon dioxide
Best for
Optical parts that must keep their shape and size over a wide temperature range (SCHOTT datasheet: CTE 0 ± 0.007 ppm/K for Expansion Class 0 Extreme)
Weakest at
Heating above 100 °C without proper cooling, which the datasheet says affects the CTE specification; the maximum application temperature is 600 °C
Risk at a glance
- People None found. No hazard classification found in a source we read
- If it fails Moderate. Breakage from sub-surface damage under tensile stress
- Corrosion Moderate. SCHOTT states that ZERODUR can be etched by hydrofluoric acid and by concentrated sulfuric acid at elevated temperatures.
Quick facts: ZERODUR
| Property | Value | Basis |
|---|---|---|
| Density | 2.53 g/cm³ | 1 sourced value |
| Young's modulus | 90.3 GPa | 1 sourced value |
| Thermal conductivity | 1.46 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 0.007 to 0.1 ppm/K | 2 sourced values across conditions |
| Specific heat | 800 J/(kg·K) | 1 sourced value |
| Maximum service temperature | 600 °C | 1 sourced value |
What is the density of ZERODUR?
ZERODUR has a density of 2.53 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of ZERODUR?
ZERODUR has a thermal conductivity of 1.46 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of ZERODUR?
ZERODUR has a coefficient of thermal expansion of 0.007 to 0.1 ppm/K. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the Young's modulus of ZERODUR?
ZERODUR has a Young's modulus of 90.3 GPa. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of ZERODUR?
ZERODUR has a maximum service temperature of 600 °C. The source and test conditions are listed in the properties table on this page.
What is ZERODUR used for?
Uses recorded in the sources include Telescope mirror substrates (monolithic and segmented telescopes); Space optics mirror substrates; Semiconductor lithography equipment.
Why it exists
ZERODUR is a lithium aluminium silicon oxide glass-ceramic whose thermal expansion is near zero over a wide temperature range. The datasheet prints a mean coefficient of linear thermal expansion of 0 ± 0.007 ppm/K for Expansion Class 0 Extreme between 0 °C and 50 °C. That property lets optical parts keep their shape and their distances while the temperature changes, which is why SCHOTT sells it for telescope mirror substrates, space optics, semiconductor lithography and ring laser gyroscopes.
Where it's used
Telescope mirrors
SCHOTT says ZERODUR is used for telescope mirror substrates in monolithic and segmented telescopes. Its largest blanks, 8 m in diameter, are the primary mirrors of ESO's Very Large Telescope.
Space optics
SCHOTT says lightweight ZERODUR mirror substrates for space optics can be made by CNC grinding, which reduces their mass by more than 90 %. The catalog ties this to thermal stability on each orbit. The flight record for a specific mission was not confirmed in a source we read.
Semiconductor lithography
SCHOTT lists semiconductor lithography and metrology among ZERODUR applications. Ring laser gyroscopes use ZERODUR special laser cavities, mirror blanks and tiny prisms, according to the product page.
Recipe
Lithium aluminium silicon oxide glass-ceramic, with nanocrystals in a residual glass phase (no single formula; oxide percentages not found in any source we hold)
ZERODUR is a lithium aluminium silicon oxide glass-ceramic. SCHOTT makes it in two steps: the raw materials are melted, cast into moulds and annealed to form a glass, and a controlled ceramization then grows nanocrystals inside that glass. The crystals have a negative coefficient of thermal expansion, which offsets the positive expansion of the residual glass.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Lithium oxide Li2O | not stated | Lithium-bearing oxide in the glass. The catalog names lithium aluminum silicon oxide as the composition. No percentage was found in a source we hold. |
| Aluminium oxide Al2O3 | not stated | Alumina component of the glass and its nanocrystal phase. No percentage was found in a source we hold. |
| Silicon dioxide SiO2 | not stated | Silica network former of the glass. No percentage was found in a source we hold. |
Weight shares are as printed in the sources.
What it can do
Thermal expansion
0.007 ppm/K
measured
The datasheet's tightest class, Expansion Class 0 Extreme, is 0 ± 0.007 ppm/K between 0 °C and 50 °C. The looser Expansion Class 2 is 0 ± 0.100 ppm/K. ZERODUR TAILORED can be optimised for a known temperature profile.
Heat conduction
1.46 W/(m·K)
measured
ZERODUR has a thermal conductivity of 1.46 W/(m·K) at 20 °C, per the datasheet.
Hardness and modulus
620 HK 0.1/20
measured
The Knoop hardness is 620 HK 0.1/20 under ISO 9385, and the Young's modulus is 90.3 GPa at 20 °C (mean value).
Optical quality
1.5424 nd
measured
The refractive index nd is 1.5424 and the Abbe number vd is 56.1. The internal transmittance is 0.95 at 580 nm for 5 mm thickness and 0.9 for 10 mm.
How it compares
Within the ZERODUR expansion classes in the same datasheet, Expansion Class 0 Extreme (0 ± 0.007 ppm/K) is the tightest tolerance printed, and Expansion Class 2 (0 ± 0.100 ppm/K) is the loosest. This record does not hold same-source values for other materials, so the comparison rows below are between ZERODUR's own properties and are not a ranking against other glasses.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | ZERODUR |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity at 20 °C | 1.46 W/(m·K)4 |
| Heat capacity (specific heat) at 20 °C | 0.8 J/(g·K)5 |
| Physical and electrical | |
| Density | 2.53 g/cm³8 |
| Knoop hardness, HK 0.1/20 | 620 HK 0.1/209 |
| Other measurements | |
| CTE, Expansion Class 0 Extreme (tolerance around zero) | 0.007 ppm/K1 |
| CTE, Expansion Class 2 (tolerance around zero) | 0.1 ppm/K2 |
| CTE homogeneity (peak to valley), blanks up to 4.0 m diameter | < 20 ppb/K3 |
| Young's modulus at 20 °C, mean value | 90.3 GPa6 |
| Poisson's ratio | 0.24 -7 |
| Refractive index ndValue printed in the SCHOTT datasheet (Table 3) | 1.542 - |
| Abbe number vd | 56.1 -10 |
| Internal transmittance, 5 mm thickness | 0.95 -11 |
| Internal transmittance, 10 mm thicknessValue printed in the SCHOTT datasheet (Table 3) | 0.9 - |
| Dielectric constant at 1 MHz | 7.4 -12 |
| Dielectric constant at 1 kHzValue printed in TIE-43 Tab. 2 (2014 version) | 8 - |
| Loss factor tan delta at 1 MHz | 0.015 -13 |
| Loss factor tan delta at 1 kHz | 0.029 -14 |
| Temperature at which resistivity is 10^8 Ω·cm | 178 °C15 |
| Maximum application temperature | 600 °C16 |
| Breakage stress threshold, D151 ground surface | 47.3 MPa17 |
| Stress optical coefficient K | 3 10-6 MPa-118 |
Why choose it, and why not
Good for
- Thermal stability. The datasheet gives 0 ± 0.007 ppm/K for Expansion Class 0 Extreme between 0 °C and 50 °C.
- Low thermal expansion over a large part. SCHOTT offers homogeneity of 20 ppb/K peak to valley for blanks up to 4.0 m in diameter.
- Optical parts. Refractive index nd is 1.5424 with an Abbe number of 56.1, per the datasheet.
Watch out for
- The maximum application temperature is 600 °C, and the CTE specification is affected by use above 100 °C without proper cooling.
- Breakage depends on the surface. A D151 ground surface has a threshold of 47.3 MPa in the datasheet's Weibull fit.
- Helium permeability rises from 1.6e6 at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C.
ZERODUR is the glass-ceramic to specify when a part must hold its shape across a wide temperature range. The datasheet supports that with the tightest expansion tolerance and a 600 °C ceiling; the space record for specific missions still needs a source.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | ZERODUR |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | CTE, Expansion Class 0 Extreme (tolerance around zero) | Tolerance class printed in the SCHOTT datasheet (CTE specification tolerances table). The value is the half-width of the tolerance around zero, not a measured mean. | grade ZERODUR, Expansion Class 0 Extremetemperature range 0 °C to 50 °Cbasis mean coefficient of linear thermal expansion, supplied as a tolerance 0 ± 0.007 ppm/K | — |
| 2 | CTE, Expansion Class 2 (tolerance around zero) | Tolerance class printed in the SCHOTT datasheet (CTE specification tolerances table) | grade ZERODUR, Expansion Class 2temperature range 0 °C to 50 °Cbasis mean coefficient of linear thermal expansion, supplied as a tolerance 0 ± 0.100 ppm/K | — |
| 3 | CTE homogeneity (peak to valley), blanks up to 4.0 m diameter | Tolerance printed in the SCHOTT datasheet (CTE homogeneity tolerances table); benchmark name is not in the canonical list | temperature range 0 °C to 50 °Cpart size up to 4.0 m diameter | — |
| 4 | Thermal conductivity at 20 °C | Value printed in the SCHOTT datasheet mechanical, optical and chemical properties table; the same value is in TIE-43 section 1 | temperature 20 °Cgrade ZERODUR (not K20) | — |
| 5 | Heat capacity (specific heat) at 20 °C | Printed in J/(g·K) in the SCHOTT datasheet; the importer converts to the canonical J/(kg·K) | temperature 20 °Cunit in source J/(gK) | — |
| 6 | Young's modulus at 20 °C, mean value | Value printed in the SCHOTT datasheet (Table 3); TIE-43 section 2 prints the same 90.3 | temperature 20 °Cbasis mean value | — |
| 7 | Poisson's ratio | Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2 | temperature not printed in the table | — |
| 8 | Density | Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2 | temperature not printed in the datasheet | — |
| 9 | Knoop hardness, HK 0.1/20 | Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2; benchmark name is not in the canonical list | standard ISO 9385load 0.1 (HK 0.1/20) | — |
| 10 | Abbe number vd | Value printed in the SCHOTT datasheet (Table 3); benchmark name is not in the canonical list | basis Abbe number as printed in the datasheet | — |
| 11 | Internal transmittance, 5 mm thickness | Value printed in the SCHOTT datasheet (Table 3); internal transmittance is the transmittance corrected for reflection losses per TIE-43 | wavelength 580 nmthickness 5 mm | — |
| 12 | Dielectric constant at 1 MHz | Value printed in TIE-43 Tab. 2 (2014 version); TIE-43 states that its data are typical values | frequency 1 MHzbasis dielectric constant, typical value | — |
| 13 | Loss factor tan delta at 1 MHz | Printed as 15 · 10–3 in TIE-43 Tab. 2 and entered as 0.015 | frequency 1 MHz | — |
| 14 | Loss factor tan delta at 1 kHz | Printed as 29 · 10–3 in TIE-43 Tab. 2 and entered as 0.029 | frequency 1 kHz | — |
| 15 | Temperature at which resistivity is 10^8 Ω·cm | Value printed in the SCHOTT datasheet (Table 3, Tk100 row); benchmark name is not in the canonical list | basis temperature for a specific resistivity of 10^8 Ω·cm | — |
| 16 | Maximum application temperature | Rating printed in the SCHOTT datasheet under the heading 'Maximum application temperature of 600 °C' and on the product page | basis maximum application temperature printed by SCHOTT for ZERODUR | — |
| 17 | Breakage stress threshold, D151 ground surface | Value printed in the SCHOTT datasheet, Weibull fit for the D151 sample; the benchmark name is not in the canonical list and this is not a flexural strength | surface D151 ground surfacemodel three-parameter Weibull fitbasis breakage stress threshold from the Weibull distribution | — |
| 18 | Stress optical coefficient K | Value printed in the SCHOTT datasheet (Table 3); benchmark name is not in the canonical list | wavelength 589.3 nm | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Water and humid air (hydrolytic and climate resistance) | low | ZERODUR is rated in the highest-resistance hydrolytic and climate classes that SCHOTT prints for the glass.1 |
| Acids and alkalis (acid and alkali resistance classes) | low | SCHOTT lists acid and alkali resistance classes of 1.0 for ZERODUR.2 |
| Hydrofluoric acid and hot concentrated sulfuric acid | moderate | SCHOTT states that ZERODUR can be etched by hydrofluoric acid and by concentrated sulfuric acid at elevated temperatures.3 |
| Heating above 100 °C | moderate | SCHOTT says the CTE specification is affected when ZERODUR is used above 100 °C and not properly cooled down.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Water and humid air (hydrolytic and climate resistance) | SCHOTT lists a hydrolytic resistance class of HGB 1 under ISO 719 and a climate resistance class of 1. The datasheet does not explain the class scale beyond these labels. | standards ISO 719 (hydrolytic); climate class as printedbasis classes printed in the datasheet; no exposure time or humidity level is stated |
| 2 | Acids and alkalis (acid and alkali resistance classes) | The datasheet prints an acid resistance class of 1.0 under ISO 8424 and an alkali resistance class of 1.0 under ISO 10629. No immersion time or concentration is given with these classes. | standards ISO 8424 (acid); ISO 10629 (alkali)basis class numbers as printed; no exposure conditions in the table |
| 3 | Hydrofluoric acid and hot concentrated sulfuric acid | The product page states that the glass-ceramic 'can be etched by hydrofluoric acid as well as concentrated sulfuric acid at elevated temperatures'. Etching is part of how mirror substrates are finished, and it also means these acids attack the surface. | temperature elevated, not quantified on the pagebasis product-page statement; no etch rate printed |
| 4 | Heating above 100 °C | The datasheet states that the CTE specifications are affected by use of ZERODUR above 100 °C and by not cooling it down properly. The maximum application temperature is 600 °C. | threshold 100 °Cmax application temp 600 °Cbasis datasheet statement; no time at temperature stated |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The supplier safety data sheet was not opened in this run. SCHOTT's brochure refers readers to its safety data sheet for safe use, handling and disposal.
- The solid
- ZERODUR is a solid, non-porous glass-ceramic (SCHOTT catalog). Hazard information for finished blanks was not found in a source we hold.
- Chemicals used in finishing
- The product page says hydrofluoric acid and hot concentrated sulfuric acid can etch the glass-ceramic. The safety data for those acids applies to the etching step.
If a part fails
The numbers below come from SCHOTT's datasheet and show how the glass behaves, not from field incidents.
- Breakage
- For a D151 ground surface, the breakage stress threshold is 47.3 MPa in a three-parameter Weibull fit. Finer grinding and etching of an appropriate surface layer raise the threshold.
- Heating
- The CTE specification is affected by use above 100 °C without proper cooling. The maximum application temperature is 600 °C.
- Helium
- Helium permeability rises from 1.6e6 atoms/(cm·s·bar) at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C, so a helium-tight seal gets leakier as it heats.
Handling and storage
- Chemicals
- Use hydrofluoric or hot concentrated sulfuric acid only where the finishing process calls for them, because the product page says both can etch the glass-ceramic.
- Temperature
- Do not exceed the 600 °C maximum application temperature, and cool the part down properly after any heating above 100 °C.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Breakage from sub-surface damage under tensile stressmoderate severity | Tensile stress on a part whose surface has sub-surface damage left by grindingFor a D151 ground surface the breakage stress threshold is 47.3 MPa in a three-parameter Weibull fit. SCHOTT says finer grinding and etching of an appropriate surface layer increase the threshold significantly. |
| Expansion specification affected after use above 100 °Cmoderate severity | Use above 100 °C without proper coolingSCHOTT says the CTE specifications are affected. The maximum application temperature is 600 °C. |
| Helium passes through the glass faster when hotlow severity | A helium-tight barrier or seal in service at elevated temperatureHelium permeability rises from 1.6e6 atoms/(cm·s·bar) at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C, as printed in the datasheet. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Optical transmission of thick transmitting parts at short wavelengths | The crystal phase scatters visible light (Rayleigh scattering), which lowers transmittance in the visible and near-UV range. SCHOTT says the scattering falls with wavelength, giving high transmittance in the far red and near infrared. |
Handling and storage
- Keep the chemical limits in mind: the product page says hydrofluoric acid and hot concentrated sulfuric acid can etch the glass-ceramic.
- Stay within 600 °C and cool the part properly after heating above 100 °C, because the CTE specification depends on it.
Mitigations
- Choose the expansion class that matches the job. The datasheet offers classes from 0 ± 0.100 ppm/K (Class 2) down to 0 ± 0.007 ppm/K (Class 0 Extreme).
- For a known temperature profile, SCHOTT offers TAILORED material optimised for the customer's temperature profile. SCHOTT states it is based on a physical material model that accounts for structural relaxation.
Supply and geography
How common the raw materials are and where they come from.
Lithium (raw material for the lithium oxide content)
- Top producers (2025)
- Australia 31.7%, China 21.4%, Chile 19.3%, Zimbabwe 9.7%, Argentina 7.9%
- Critical mineral lists
- US: listed, EU: listed
- Recycling
- USGS: construction of lithium battery recycling plants continued throughout 2025. The USGS lithium chapter does not describe recycling of glass.
- Substitutes
- USGS: substitution for lithium compounds is possible in batteries, ceramics, greases and manufactured glass.
Aluminium oxide (alumina, refined from bauxite)
- Top producers (2025)
- China 62%, Australia 11.3%, Brazil 7.3%, India 5.5%
- Critical mineral lists
- US: listed, EU: listed
- Recycling
- USGS: Recycling: None (bauxite and alumina chapter).
- Substitutes
- USGS: silicon carbide and alumina zirconia can substitute for alumina and bauxite in abrasives but cost more.
Silicon (silica, SiO2, from quartz sand)
- Critical mineral lists
- US: listed, EU: listed
- Recycling
- Not found in the USGS silicon chapter read in this run (it reports recycling as insignificant for ferrosilicon and silicon metal).
Documents
Datasheets, safety data sheets, papers and standards you can open.
| Document | Type | Year |
|---|---|---|
| ZERODUR datasheet, ENGLISH/US 08/2024 (SCHOTT) | datasheet | 2024 |
| TIE-43 Properties of ZERODUR (SCHOTT technical information, version July 2014) | datasheet | 2014 |
| ZERODUR product catalog (SCHOTT, undated) | datasheet | 2026 |
| USGS Mineral Commodity Summaries 2026: Lithium | report | 2026 |
| USGS Mineral Commodity Summaries 2026: Bauxite and Alumina | report | 2026 |
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: zerodur
spore_version: 0.2
family: glass-ceramics
name: ZERODUR (lithium aluminium silicon oxide glass-ceramic)
abbreviation: ZERODUR
role: near-zero-expansion optical glass-ceramic
category: ceramics
type: glass-ceramics
summary: |
ZERODUR is a lithium aluminium silicon oxide glass-ceramic made by SCHOTT at Mainz, Germany. Its datasheet gives a mean coefficient of linear thermal expansion of 0 ± 0.007 ppm/K for Expansion Class 0 Extreme between 0 °C and 50 °C, a density of 2.53 g/cm3 and a Young's modulus of 90.3 GPa at 20 °C. It is used for telescope mirror substrates, space optics, semiconductor lithography and ring laser gyroscopes. SCHOTT rates its maximum application temperature at 600 °C.
best_for: 'Optical parts that must keep their shape and size over a wide temperature range (SCHOTT datasheet: CTE 0 ± 0.007 ppm/K for Expansion Class 0 Extreme)'
weakest_at: Heating above 100 °C without proper cooling, which the datasheet says affects the CTE specification; the maximum application temperature is 600 °C
identity:
formula: Lithium aluminium silicon oxide glass-ceramic, with nanocrystals in a residual glass phase (no single formula; oxide percentages not found in any source we hold)
source: schott-catalog
where: 'Introduction, first paragraph: ''inorganic, non-porous lithium aluminum silicon oxide glass-ceramic'''
designations:
- system: Trade name
code: ZERODUR
source: schott-datasheet
where: Title of the datasheet, ZERODUR glass-ceramic with near-zero thermal expansion
tags:
environments: []
stresses:
- extreme-heat
applications:
- optics-and-cameras
- electronics-and-chips
properties:
- benchmark: cte
label: CTE, Expansion Class 0 Extreme (tolerance around zero)
value: 0.007
unit: ppm/K
scope: material
conditions:
grade: ZERODUR, Expansion Class 0 Extreme
temperature_range: 0 °C to 50 °C
basis: mean coefficient of linear thermal expansion, supplied as a tolerance 0 ± 0.007 ppm/K
method: Tolerance class printed in the SCHOTT datasheet (CTE specification tolerances table). The value is the half-width of the tolerance around zero, not a measured mean.
status: ground
source: schott-datasheet
where: Table 1, Expansion Class 0 Extreme row
- benchmark: cte
label: CTE, Expansion Class 2 (tolerance around zero)
value: 0.1
unit: ppm/K
scope: material
conditions:
grade: ZERODUR, Expansion Class 2
temperature_range: 0 °C to 50 °C
basis: mean coefficient of linear thermal expansion, supplied as a tolerance 0 ± 0.100 ppm/K
method: Tolerance class printed in the SCHOTT datasheet (CTE specification tolerances table)
status: ground
source: schott-datasheet
where: Table 1, Expansion Class 2 row
- benchmark: cte_homogeneity
label: CTE homogeneity (peak to valley), blanks up to 4.0 m diameter
value: 20
bound: upper
unit: ppb/K
scope: material
conditions:
temperature_range: 0 °C to 50 °C
part_size: up to 4.0 m diameter
method: Tolerance printed in the SCHOTT datasheet (CTE homogeneity tolerances table); benchmark name is not in the canonical list
status: ground
source: schott-datasheet
where: Table 2, row 'up to 4.0 m diameter'
- benchmark: thermal_conductivity
label: Thermal conductivity at 20 °C
value: 1.46
unit: W/(m·K)
scope: material
conditions:
temperature: 20 °C
grade: ZERODUR (not K20)
method: Value printed in the SCHOTT datasheet mechanical, optical and chemical properties table; the same value is in TIE-43 section 1
status: ground
source: schott-datasheet
where: Table 3, thermal conductivity row
- benchmark: specific_heat
label: Heat capacity (specific heat) at 20 °C
value: 0.8
unit: J/(g·K)
scope: material
conditions:
temperature: 20 °C
unit_in_source: J/(g · K)
method: Printed in J/(g·K) in the SCHOTT datasheet; the importer converts to the canonical J/(kg·K)
status: ground
source: schott-datasheet
where: Table 3, heat capacity cp row
- benchmark: elastic_modulus
label: Young's modulus at 20 °C, mean value
value: 90.3
unit: GPa
scope: material
conditions:
temperature: 20 °C
basis: mean value
method: Value printed in the SCHOTT datasheet (Table 3); TIE-43 section 2 prints the same 90.3
status: ground
source: schott-datasheet
where: Table 3, Young's modulus row (mean value)
- benchmark: poissons_ratio
label: Poisson's ratio
value: 0.24
unit: '-'
scope: material
conditions:
temperature: not printed in the table
method: Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2
status: ground
source: schott-datasheet
where: Table 3, Poisson's ratio row
- benchmark: density
label: Density
value: 2.53
unit: g/cm3
scope: material
conditions:
temperature: not printed in the datasheet
method: Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2
status: ground
source: schott-datasheet
where: Table 3, density row
- benchmark: knoop_hardness
label: Knoop hardness, HK 0.1/20
value: 620
unit: HK 0.1/20
scope: material
conditions:
standard: ISO 9385
load: 0.1 (HK 0.1/20)
method: Value printed in the SCHOTT datasheet (Table 3) and in TIE-43 section 2; benchmark name is not in the canonical list
status: ground
source: schott-datasheet
where: Table 3, Knoop hardness row
- benchmark: refractive_index
label: Refractive index nd
value: 1.5424
unit: '-'
scope: material
conditions:
basis: nd as printed in the datasheet; the wavelength is not restated in the table
method: Value printed in the SCHOTT datasheet (Table 3)
status: ground
source: schott-datasheet
where: Table 3, refractive index nd row
- benchmark: abbe_number
label: Abbe number vd
value: 56.1
unit: '-'
scope: material
conditions:
basis: Abbe number as printed in the datasheet
method: Value printed in the SCHOTT datasheet (Table 3); benchmark name is not in the canonical list
status: ground
source: schott-datasheet
where: Table 3, Abbe number vd row
- benchmark: internal_transmittance
label: Internal transmittance, 5 mm thickness
value: 0.95
unit: '-'
scope: material
conditions:
wavelength: 580 nm
thickness: 5 mm
method: Value printed in the SCHOTT datasheet (Table 3); internal transmittance is the transmittance corrected for reflection losses per TIE-43
status: ground
source: schott-datasheet
where: Table 3, internal transmittance 5 mm row
- benchmark: internal_transmittance
label: Internal transmittance, 10 mm thickness
value: 0.9
unit: '-'
scope: material
conditions:
wavelength: 580 nm
thickness: 10 mm
method: Value printed in the SCHOTT datasheet (Table 3)
status: ground
source: schott-datasheet
where: Table 3, internal transmittance 10 mm row
- benchmark: dielectric_constant
label: Dielectric constant at 1 MHz
value: 7.4
unit: '-'
scope: material
conditions:
frequency: 1 MHz
basis: dielectric constant, typical value
method: Value printed in TIE-43 Tab. 2 (2014 version); TIE-43 states that its data are typical values
status: ground
source: schott-tie43
where: Section 3, Tab. 2 (Dielectric properties), column at 1 MHz
- benchmark: dielectric_constant
label: Dielectric constant at 1 kHz
value: 8
unit: '-'
scope: material
conditions:
frequency: 1 kHz
basis: dielectric constant, typical value
method: Value printed in TIE-43 Tab. 2 (2014 version)
status: ground
source: schott-tie43
where: Section 3, Tab. 2 (Dielectric properties), column at 1 kHz
- benchmark: dissipation_factor
label: Loss factor tan delta at 1 MHz
value: 0.015
unit: '-'
scope: material
conditions:
frequency: 1 MHz
method: Printed as 15 · 10–3 in TIE-43 Tab. 2 and entered as 0.015
status: ground
source: schott-tie43
where: Section 3, Tab. 2 (Dielectric properties), column at 1 MHz
- benchmark: dissipation_factor
label: Loss factor tan delta at 1 kHz
value: 0.029
unit: '-'
scope: material
conditions:
frequency: 1 kHz
method: Printed as 29 · 10–3 in TIE-43 Tab. 2 and entered as 0.029
status: ground
source: schott-tie43
where: Section 3, Tab. 2 (Dielectric properties), column at 1 kHz
- benchmark: tk100
label: Temperature at which resistivity is 10^8 Ω·cm
value: 178
unit: °C
scope: material
conditions:
basis: temperature for a specific resistivity of 10^8 Ω·cm
method: Value printed in the SCHOTT datasheet (Table 3, Tk100 row); benchmark name is not in the canonical list
status: ground
source: schott-datasheet
where: Table 3, Tk100 row
- benchmark: max_service_temp
label: Maximum application temperature
value: 600
unit: °C
scope: material
conditions:
basis: maximum application temperature printed by SCHOTT for ZERODUR
method: Rating printed in the SCHOTT datasheet under the heading 'Maximum application temperature of 600 °C' and on the product page
status: ground
source: schott-datasheet
where: Page 3, heading 'Maximum application temperature of 600 °C'
- benchmark: breakage_stress_threshold
label: Breakage stress threshold, D151 ground surface
value: 47.3
unit: MPa
scope: material
conditions:
surface: D151 ground surface
model: three-parameter Weibull fit
basis: breakage stress threshold from the Weibull distribution
method: Value printed in the SCHOTT datasheet, Weibull fit for the D151 sample; the benchmark name is not in the canonical list and this is not a flexural strength
status: ground
source: schott-datasheet
where: Page 3, 'Extensive data on the strength of ZERODUR', text above Figure 2
- benchmark: stress_optical_coefficient
label: Stress optical coefficient K
value: 3
unit: 10-6 MPa-1
scope: material
conditions:
wavelength: 589.3 nm
method: Value printed in the SCHOTT datasheet (Table 3); benchmark name is not in the canonical list
status: ground
source: schott-datasheet
where: Table 3, stress optical coefficient K row
corrosion:
- environment: Water and humid air (hydrolytic and climate resistance)
headline: ZERODUR is rated in the highest-resistance hydrolytic and climate classes that SCHOTT prints for the glass.
effect: SCHOTT lists a hydrolytic resistance class of HGB 1 under ISO 719 and a climate resistance class of 1. The datasheet does not explain the class scale beyond these labels.
rating: low
conditions:
standards: ISO 719 (hydrolytic); climate class as printed
basis: classes printed in the datasheet; no exposure time or humidity level is stated
source: schott-datasheet
where: Table 3, hydrolytic resistance class and climate resistance rows
- environment: Acids and alkalis (acid and alkali resistance classes)
headline: SCHOTT lists acid and alkali resistance classes of 1.0 for ZERODUR.
effect: The datasheet prints an acid resistance class of 1.0 under ISO 8424 and an alkali resistance class of 1.0 under ISO 10629. No immersion time or concentration is given with these classes.
rating: low
conditions:
standards: ISO 8424 (acid); ISO 10629 (alkali)
basis: class numbers as printed; no exposure conditions in the table
source: schott-datasheet
where: Table 3, acid resistance and alkali resistance rows
- environment: Hydrofluoric acid and hot concentrated sulfuric acid
headline: SCHOTT states that ZERODUR can be etched by hydrofluoric acid and by concentrated sulfuric acid at elevated temperatures.
effect: The product page states that the glass-ceramic 'can be etched by hydrofluoric acid as well as concentrated sulfuric acid at elevated temperatures'. Etching is part of how mirror substrates are finished, and it also means these acids attack the surface.
rating: moderate
conditions:
temperature: elevated, not quantified on the page
basis: product-page statement; no etch rate printed
source: schott-product-page
where: FAQ answer on chemical resistance
- environment: Heating above 100 °C
headline: SCHOTT says the CTE specification is affected when ZERODUR is used above 100 °C and not properly cooled down.
effect: The datasheet states that the CTE specifications are affected by use of ZERODUR above 100 °C and by not cooling it down properly. The maximum application temperature is 600 °C.
rating: moderate
conditions:
threshold: 100 °C
max_application_temp: 600 °C
basis: datasheet statement; no time at temperature stated
source: schott-datasheet
where: Page 3, heading 'Maximum application temperature of 600 °C'
risks:
hazards:
- text: SCHOTT's brochure tells users to refer to the Safety Data Sheet for information on safe use, handling and disposal. The SDS was not opened in this run, so no GHS classification for ZERODUR is entered.
ghs: []
source: schott-catalog
where: Disclaimer page
failure_risks:
- mode: Breakage from sub-surface damage under tensile stress
trigger: Tensile stress on a part whose surface has sub-surface damage left by grinding
consequence: For a D151 ground surface the breakage stress threshold is 47.3 MPa in a three-parameter Weibull fit. SCHOTT says finer grinding and etching of an appropriate surface layer increase the threshold significantly.
severity: moderate
source: schott-datasheet
where: Page 3, 'Extensive data on the strength of ZERODUR'
- mode: Expansion specification affected after use above 100 °C
trigger: Use above 100 °C without proper cooling
consequence: SCHOTT says the CTE specifications are affected. The maximum application temperature is 600 °C.
severity: moderate
source: schott-datasheet
where: Page 3, heading 'Maximum application temperature of 600 °C'
- mode: Helium passes through the glass faster when hot
trigger: A helium-tight barrier or seal in service at elevated temperature
consequence: Helium permeability rises from 1.6e6 atoms/(cm·s·bar) at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C, as printed in the datasheet.
severity: low
source: schott-datasheet
where: Table 3, helium permeability rows
side_effects:
- text: The crystal phase scatters visible light (Rayleigh scattering), which lowers transmittance in the visible and near-UV range. SCHOTT says the scattering falls with wavelength, giving high transmittance in the far red and near infrared.
affects: Optical transmission of thick transmitting parts at short wavelengths
source: schott-tie43
where: Section 4.2 Internal transmittance, text after Fig. 5 and Tab. 7
handling:
- text: 'Keep the chemical limits in mind: the product page says hydrofluoric acid and hot concentrated sulfuric acid can etch the glass-ceramic.'
source: schott-product-page
where: FAQ answer on chemical resistance
- text: Stay within 600 °C and cool the part properly after heating above 100 °C, because the CTE specification depends on it.
source: schott-datasheet
where: Page 3, maximum application temperature
mitigations:
- text: Choose the expansion class that matches the job. The datasheet offers classes from 0 ± 0.100 ppm/K (Class 2) down to 0 ± 0.007 ppm/K (Class 0 Extreme).
source: schott-datasheet
where: Table 1, CTE specification tolerances
- text: For a known temperature profile, SCHOTT offers TAILORED material optimised for the customer's temperature profile. SCHOTT states it is based on a physical material model that accounts for structural relaxation.
source: schott-datasheet
where: Page 2, ZERODUR TAILORED box
uses:
- application: optics-and-cameras
device: Telescope mirror substrates (monolithic and segmented telescopes)
example: SCHOTT says ZERODUR is used for telescope mirror substrates in monolithic and segmented telescopes. Its largest blanks, 8 m in diameter, are the primary mirrors of ESO's Very Large Telescope.
source: schott-catalog
where: Astronomy section, 'The largest ZERODUR blanks ever made'
- application: optics-and-cameras
device: Space optics mirror substrates
example: SCHOTT says mirror substrates for space optics are typically lightweight because CNC grinding can reduce their mass by more than 90 %, and that near-zero expansion keeps them stable on each orbit.
source: schott-catalog
where: Space section, text beside the 1.2 m blank photograph
- application: electronics-and-chips
device: Semiconductor lithography equipment
example: SCHOTT lists semiconductor lithography among ZERODUR applications and states that miniaturization in integrated circuit systems requires very precise lithography and wafer positioning.
source: schott-product-page
where: Applications FAQ, lithography answer
supply:
- subject: Lithium (raw material for the lithium oxide content)
producers:
- country: Australia
share_percent: 31.7
year: 2025
- country: China
share_percent: 21.4
year: 2025
- country: Chile
share_percent: 19.3
year: 2025
- country: Zimbabwe
share_percent: 9.7
year: 2025
- country: Argentina
share_percent: 7.9
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals (Lithium, used in rechargeable batteries)
listed: true
- list: EU critical raw materials list (Lithium)
listed: true
recycling: 'USGS: construction of lithium battery recycling plants continued throughout 2025. The USGS lithium chapter does not describe recycling of glass.'
substitutes:
- 'USGS: substitution for lithium compounds is possible in batteries, ceramics, greases and manufactured glass.'
source: usgs-mcs2026-lithium
where: World Mine Production and Reserves table, 2025 column (world total about 290,000 t, stated in the text; shares calculated by Space Mushroom against that total, which excludes United States output)
- subject: Aluminium oxide (alumina, refined from bauxite)
producers:
- country: China
share_percent: 62
year: 2025
- country: Australia
share_percent: 11.3
year: 2025
- country: Brazil
share_percent: 7.3
year: 2025
- country: India
share_percent: 5.5
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals (Aluminum, used in almost all sectors of the economy)
listed: true
- list: EU critical raw materials list (Bauxite; aluminium and bauxite merged)
listed: true
recycling: 'USGS: Recycling: None (bauxite and alumina chapter).'
substitutes:
- 'USGS: silicon carbide and alumina zirconia can substitute for alumina and bauxite in abrasives but cost more.'
source: usgs-mcs2026-bauxite-alumina
where: World Alumina Refinery and Bauxite Mine Production table, alumina 2025e (world total 150,000 thousand t; shares calculated by Space Mushroom). The chapter does not break out the glass-ceramic grade.
- subject: Silicon (silica, SiO2, from quartz sand)
producers: []
critical_lists:
- list: USGS 2025 List of Critical Minerals (Silicon, used in silicon wafers)
listed: true
- list: EU critical raw materials list (Silicon metal)
listed: true
recycling: Not found in the USGS silicon chapter read in this run (it reports recycling as insignificant for ferrosilicon and silicon metal).
substitutes: []
source: usgs-critical-2025
where: Final 2025 critical minerals list (Silicon); EU list (Silicon metal). No world production table for silicon was read in this run.
media: []
documents:
- title: ZERODUR datasheet, ENGLISH/US 08/2024 (SCHOTT)
type: datasheet
url: https://media.schott.com/api/public/content/7c351fbb693b443aa741fcfe72a31755?v=b5370fd8&download=true
year: 2024
- title: TIE-43 Properties of ZERODUR (SCHOTT technical information, version July 2014)
type: datasheet
url: https://media.schott.com/api/public/content/d46fdbce1a35483b8db4622bdd78e043?v=fca382d5&download=true
year: 2014
- title: ZERODUR product catalog (SCHOTT, undated)
type: datasheet
url: https://media.schott.com/api/public/content/9c3ac61113624aac8033e88352f63ff0?v=62a31554&download=true
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Lithium'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Bauxite and Alumina'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
year: 2026
gaps:
- Oxide composition percentages (Li2O, Al2O3, SiO2 and the minor oxides) were not found in any source read in this run; Wikipedia names the three main oxides without percentages.
- Fracture toughness was not found on a manufacturer page read in this run. A figure appears in Wikipedia, but Wikipedia is used here for composition and history only, so it is not entered.
- No safety data sheet or PubChem GHS record for the ZERODUR glass-ceramic could be opened. A PubChem name search for lithium aluminosilicate returned petalite, a different mineral, so it is not used.
- Meteosat imager and LISA Pathfinder optical bench are named as Zerodur applications only in Wikipedia. The SCHOTT catalog shows a LISA Pathfinder launch photograph credited to ESA but does not name Zerodur for that mission. An ESA page could not be opened (HTTP 404), so flight heritage is not confirmed here.
- No flight result, vacuum outgassing (TML/CVCM), atomic-oxygen, ultraviolet or radiation test result for ZERODUR was found in a source read in this run.
- No introduction year for ZERODUR was found in a source read in this run. The catalog says SCHOTT has produced it for over 50 years in Mainz and describes an order of 12 blanks, from 0.3 m to 3.6 m in diameter, from the Max Planck Institute of Astronomy for Calar Alto; the catalog gives no year for that order.
- ZERODUR K20 and ZERODUR TAILORED values on the datasheet are separate grades or options and are not entered here. The expansion-class tolerances for ZERODUR are entered instead.
- Long-term load guidance (for example a 10 MPa tensile threshold and 30 to 100 MPa for tens of years) appears only in a summary of the SCHOTT downloads page and was not confirmed in the datasheet, so it is not entered.
- Knoop hardness, abbe number, internal transmittance, helium permeability, stress optical coefficient, CTE homogeneity, breakage stress threshold and the tk100 temperature are not in the canonical property list, so snake_case names are used. Knoop hardness and the other snake_case names are flagged in each property's method.
- 'Silicon production shares were not found: the USGS silicon chapter read in this run covers United States production and imports, and the world production table was not in the text extract.'
- Volume resistivity at other temperatures (TIE-43 Tab. 1) and the refractive index dispersion table (TIE-43 Tab. 3) are present in the TIE-43 document but were not entered, because the table layout in the PDF text extract was not clean enough to copy every value with confidence.
- Density of 2.53 g/cm3 is printed without a temperature in the datasheet, and the Poisson's ratio is printed without one as well.
- Electrical resistivity at 20 °C and helium permeability at 20 °C and 200 °C were removed from properties. The datasheet prints them with superscript exponents (2.6 · 10^13 Ω·cm; 1.6 · 10^6 and 7.2 · 10^8 atoms/(cm·s·bar)), which the text extraction flattened, so verify-values could not match them. They can be re-added once checked against the PDF by eye. The helium figures still appear in the failure-risk text.
sources:
schott-datasheet:
title: ZERODUR glass-ceramic with near-zero thermal expansion (SCHOTT datasheet, ENGLISH/US 08/2024)
id: SCHOTT datasheet, ENGLISH/US 08/2024
url: https://media.schott.com/api/public/content/7c351fbb693b443aa741fcfe72a31755?v=b5370fd8&download=true
year: 2024
kind: datasheet
license: supplier document, linked not reproduced
schott-tie43:
title: TIE-43 Properties of ZERODUR (SCHOTT Advanced Optics technical information)
id: SCHOTT TIE-43, version July 2014
url: https://media.schott.com/api/public/content/d46fdbce1a35483b8db4622bdd78e043?v=fca382d5&download=true
year: 2014
kind: datasheet
license: supplier document, linked not reproduced
schott-catalog:
title: ZERODUR product catalog (SCHOTT, glass-ceramic brochure)
id: SCHOTT ZERODUR product catalog (undated PDF, accessed 2026-11-01)
url: https://media.schott.com/api/public/content/9c3ac61113624aac8033e88352f63ff0?v=62a31554&download=true
year: 2026
kind: datasheet
license: supplier document, linked not reproduced
schott-product-page:
title: ZERODUR product page and FAQ (SCHOTT)
id: SCHOTT product ZERODUR P1000269 (undated page, accessed 2026-11-01)
url: https://www.schott.com/en-us/products/zerodur-p1000269
year: 2026
kind: web
license: supplier web page, linked not reproduced
usgs-mcs2026-lithium:
title: Mineral Commodity Summaries 2026, Lithium
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-bauxite-alumina:
title: Mineral Commodity Summaries 2026, Bauxite and Alumina
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-critical-2025:
title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
id: Final 2025 List of Critical Minerals, November 2025
url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
year: 2025
kind: web
license: public domain (USGS)
ec-crm:
title: Critical raw materials (European Commission, list under Regulation (EU) 2024/1252)
id: Regulation (EU) 2024/1252
url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
year: 2024
kind: web
license: European Commission web page
wikipedia-zerodur:
title: Zerodur (Wikipedia article), used for composition only
id: Wikipedia, Zerodur
url: https://en.wikipedia.org/wiki/Zerodur
year: 2026
kind: web
license: CC BY-SA (Wikipedia)
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 21
unreachable: 1
caveats: 4
note: 'Written by an AI assistant on 2026-11-01 from SCHOTT datasheet 08/2024, TIE-43 (2014), the SCHOTT catalog and product page, and USGS 2026 summaries, all read in this run. Caveats: the product-page quotes come from a summarising fetch; the ESA LISA Pathfinder page returned 404; several benchmark names are not canonical; composition percentages not found.'
story:
recipe:
line: 'ZERODUR is a lithium aluminium silicon oxide glass-ceramic. SCHOTT makes it in two steps: the raw materials are melted, cast into moulds and annealed to form a glass, and a controlled ceramization then grows nanocrystals inside that glass. The crystals have a negative coefficient of thermal expansion, which offsets the positive expansion of the residual glass.'
parts:
- name: Lithium oxide
symbol: Li2O
role: Lithium-bearing oxide in the glass. The catalog names lithium aluminum silicon oxide as the composition. No percentage was found in a source we hold.
- name: Aluminium oxide
symbol: Al2O3
role: Alumina component of the glass and its nanocrystal phase. No percentage was found in a source we hold.
- name: Silicon dioxide
symbol: SiO2
role: Silica network former of the glass. No percentage was found in a source we hold.
risk_groups:
- title: For people
level: 0
verdict: No hazard classification found in a source we read
lead: The supplier safety data sheet was not opened in this run. SCHOTT's brochure refers readers to its safety data sheet for safe use, handling and disposal.
points:
- label: The solid
line: ZERODUR is a solid, non-porous glass-ceramic (SCHOTT catalog). Hazard information for finished blanks was not found in a source we hold.
- label: Chemicals used in finishing
line: The product page says hydrofluoric acid and hot concentrated sulfuric acid can etch the glass-ceramic. The safety data for those acids applies to the etching step.
- title: If a part fails
lead: The numbers below come from SCHOTT's datasheet and show how the glass behaves, not from field incidents.
points:
- label: Breakage
line: For a D151 ground surface, the breakage stress threshold is 47.3 MPa in a three-parameter Weibull fit. Finer grinding and etching of an appropriate surface layer raise the threshold.
- label: Heating
line: The CTE specification is affected by use above 100 °C without proper cooling. The maximum application temperature is 600 °C.
- label: Helium
line: Helium permeability rises from 1.6e6 atoms/(cm·s·bar) at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C, so a helium-tight seal gets leakier as it heats.
- title: Handling and storage
points:
- label: Chemicals
line: Use hydrofluoric or hot concentrated sulfuric acid only where the finishing process calls for them, because the product page says both can etch the glass-ceramic.
- label: Temperature
line: Do not exceed the 600 °C maximum application temperature, and cool the part down properly after any heating above 100 °C.
why: ZERODUR is a lithium aluminium silicon oxide glass-ceramic whose thermal expansion is near zero over a wide temperature range. The datasheet prints a mean coefficient of linear thermal expansion of 0 ± 0.007 ppm/K for Expansion Class 0 Extreme between 0 °C and 50 °C. That property lets optical parts keep their shape and their distances while the temperature changes, which is why SCHOTT sells it for telescope mirror substrates, space optics, semiconductor lithography and ring laser gyroscopes.
uses:
- where: Telescope mirrors
line: SCHOTT says ZERODUR is used for telescope mirror substrates in monolithic and segmented telescopes. Its largest blanks, 8 m in diameter, are the primary mirrors of ESO's Very Large Telescope.
- where: Space optics
line: SCHOTT says lightweight ZERODUR mirror substrates for space optics can be made by CNC grinding, which reduces their mass by more than 90 %. The catalog ties this to thermal stability on each orbit. The flight record for a specific mission was not confirmed in a source we read.
- where: Semiconductor lithography
line: SCHOTT lists semiconductor lithography and metrology among ZERODUR applications. Ring laser gyroscopes use ZERODUR special laser cavities, mirror blanks and tiny prisms, according to the product page.
can_do:
- label: Thermal expansion
benchmark: cte
line: The datasheet's tightest class, Expansion Class 0 Extreme, is 0 ± 0.007 ppm/K between 0 °C and 50 °C. The looser Expansion Class 2 is 0 ± 0.100 ppm/K. ZERODUR TAILORED can be optimised for a known temperature profile.
- label: Heat conduction
benchmark: thermal_conductivity
value: 1.46 W/(m·K)
line: ZERODUR has a thermal conductivity of 1.46 W/(m·K) at 20 °C, per the datasheet.
- label: Hardness and modulus
benchmark: knoop_hardness
value: 620 HK 0.1/20
line: The Knoop hardness is 620 HK 0.1/20 under ISO 9385, and the Young's modulus is 90.3 GPa at 20 °C (mean value).
- label: Optical quality
benchmark: refractive_index
value: 1.5424 nd
line: The refractive index nd is 1.5424 and the Abbe number vd is 56.1. The internal transmittance is 0.95 at 580 nm for 5 mm thickness and 0.9 for 10 mm.
compare: Within the ZERODUR expansion classes in the same datasheet, Expansion Class 0 Extreme (0 ± 0.007 ppm/K) is the tightest tolerance printed, and Expansion Class 2 (0 ± 0.100 ppm/K) is the loosest. This record does not hold same-source values for other materials, so the comparison rows below are between ZERODUR's own properties and are not a ranking against other glasses.
compare_rows:
- label: Thermal expansion tolerance
benchmark: cte
- label: Heat conduction
benchmark: thermal_conductivity
- label: Stiffness
benchmark: elastic_modulus
handling:
- Expansion Class 0 Extreme is the tightest tolerance on the datasheet. SCHOTT's TIE-43 says the printed data are typical values and that single batches can vary slightly.
- Keep the part at or below 600 °C, and cool it properly after heating above 100 °C.
- Etch with hydrofluoric or hot concentrated sulfuric acid only in a qualified finishing process.
good_for:
- Thermal stability. The datasheet gives 0 ± 0.007 ppm/K for Expansion Class 0 Extreme between 0 °C and 50 °C.
- Low thermal expansion over a large part. SCHOTT offers homogeneity of 20 ppb/K peak to valley for blanks up to 4.0 m in diameter.
- Optical parts. Refractive index nd is 1.5424 with an Abbe number of 56.1, per the datasheet.
watch_out:
- The maximum application temperature is 600 °C, and the CTE specification is affected by use above 100 °C without proper cooling.
- Breakage depends on the surface. A D151 ground surface has a threshold of 47.3 MPa in the datasheet's Weibull fit.
- Helium permeability rises from 1.6e6 at 20 °C to 7.2e8 atoms/(cm·s·bar) at 200 °C.
verdict: ZERODUR is the glass-ceramic to specify when a part must hold its shape across a wide temperature range. The datasheet supports that with the tightest expansion tolerance and a 600 °C ceiling; the space record for specific missions still needs a source.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| ZERODUR glass-ceramic with near-zero thermal expansion (SCHOTT datasheet, ENGLISH/US 08/2024) | datasheet | 2024 | 26 values | |
| TIE-43 Properties of ZERODUR (SCHOTT Advanced Optics technical information) | datasheet | 2014 | 5 values | |
| ZERODUR product catalog (SCHOTT, glass-ceramic brochure) | datasheet | 2026 | 4 values | |
| ZERODUR product page and FAQ (SCHOTT) | web | 2026 | 3 values | |
| Mineral Commodity Summaries 2026, Lithium | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Bauxite and Alumina | report | 2026 | 1 value | |
| About the 2025 List of Critical Minerals (USGS, final list of 60 minerals) | web | 2025 | 1 value | |
| Critical raw materials (European Commission, list under Regulation (EU) 2024/1252) | web | 2024 | 0 values | |
| Zerodur (Wikipedia article), used for composition only | web | 2026 | 0 values |
Updated