Home / Products / Glass Ceramics / ZERODUR transparent glass-ceramic from SCHOTT


Transparent glass ceramic with zero expansion

Special Properties

  • Extremely low coefficient of thermal expansion
  • Excellent material homogeneity and purity
  • High operating temperature
  • High CTE homogeneity
  • Excellent chemical stability

Typical Applications

  • Ultra-precision optics
  • Mirror substrates for large astronomical telescopes
  • Substrates for X-ray telescopes
  • Ring laser gyroscope applications
  • Optical elements for comet probes
  • Flat optics and optical flats
  • Space technology
  • Low expansion laser optics
  • Glass standards for precision measurement technology
  • Mechanical laser resonator components
  • Components and holders for fiber optics
  • Lightweight honeycomb satellite mirror mounts

Related products

  • ULE® (Ultra-low expansion glass)

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ZERODUR® glass-ceramic from SCHOTT is an inorganic, non-porous lithium aluminum silicon-oxide material made by controlled volume crystallization. It contains a crystallized phase and a rest glass phase, which creates this exceptional material's unique properties.

Finished block of ZERODUR® glass ceramic from SCHOTT

ZERODUR® glass block
with drilled holes

Unlike most glass materials, ZERODUR® has an extremely low coefficient of thermal expansion (CTE) that can even become zero or slightly negative at some temperatures. The expansion is also much smaller than that of quartz glass or fused silica.

Another unique characteristic of ZERODUR® is its high homogeneity. Even in large ZERODUR® material blocks, the fluctuations of mechanical and thermal properties are nearly not measurable. Good transparency in the range of about 400–2300 nm allows verification of the inner quality of ZERODUR®. Therefore, neither bubbles nor inclusions are undetected. Our company uses different available material grades of ZERODUR® glass-ceramic to manufacture substrates for high-quality optics used for high-end applications in research, science, industry, space technology, and astronomy. However, for the design of length standards, large telescope mirrors, laser cavities, coating substrates, and mechanical components for fiber optics, ZERODUR® high-performance glass-ceramic is an ideal material choice.


Our company machines all kinds of optics for a broad range of applications from these fascinating glass-ceramic materials. To request a quotation for a finished part made of original ZERODUR® glass-ceramic from SCHOTT at custom dimensions, please use the button below:


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  • Density: 2,53 g/cm3
  • Young's Modulus: 90,3 GPa (mean value)
  • Poisson's ratio: 0,24
  • Knoop hardness : 620 (HK 0,1/20 ; ISO 9385)


  • Coefficient of thermal expansion (CTE):
    • Class 0 materials: 0 ± 0,02 × 10-6/K
    • Class 1 materials: 0 ± 0,05 × 10-6/K
    • Class 2 materials: 0 ± 0,10 × 10-6/K
    • Show curve of length expansion
  • Total change of length (-50 to +100 °C):
    • < 10 × 10-6/K per length of the part
  • Recommended cooling rate for applications at temperatures of 130–320 °C:
    • According to SCHOTT small changes of the CTE might occur if ZERODUR® glass-ceramic is cooled down from between 130–320 °C to room temperature at a cooling rate that deviates from the cooling-rate used during the production of ZERODUR®. The initial cooling rate during production is between 1 °C/h and 6 °C/h. A factor of 10 difference between the production cooling rate and the application's cooling-rate may result in a permanent change of the CTE of 0,025 10-6/K.
  • Max. operating temperature:
    • 600 °C
  • Thermal conductivity:
    • 1,46 W/(m x K) (at 20 °C)
  • Thermal diffusivity index:
    • 0,72 × 10-6 m2/s (at 20 °C)
  • Heat capacity:
    • 0,80 J/(g × K) (at 20 °C)


Hydrolytic Resistance
  • (ISO 719) HGB 1
Alkali resistance
  • (ISO under construction) Class 1.0
Acid Resistance
  • (ISO 8424) Class 1.0

Stain resistance

  • Class 0


Electrical resistivity (at 20 °C)

  • 2,6 × 1013 (Ohm x cm)
Dielectric Constant
  • 8,0 (1 kHz)
  • 7,4 (1 MHz)
Loss Factor tan d
  • 29 × 10-3 (1 kHz)
  • 15 × 10-3 (1 MHz)


Surface Quality

For further detailed specifications and additional data on ZERODUR® glass-ceramic, please use our information request page.


All given details and specifications are mean reference values and are not guaranteed. Also, please consider our "Notes on specifications".


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Last update: April 20, 2024