Technical glass ceramics picture, Zerodur
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ZERODUR® Transparent Glass Ceramic

Glass ceramic with zero expansion

Special Properties

  • Ultra low thermal expansion over a wide temperature range
  • High material homogeneity and purity
  • High operating temperature
  • High CTE homogeneity
  • Very good chemical stability

Typical Applications

  • Ultra precision optics
  • Mirror substrates for large astronomical telescopes
  • Mirror substrates for X-ray telescopes
  • Optical elements for comet probes
  • Ring laser gyroscopes
  • Space technology applications
  • Standards for precision measurement technology
  • Lightweight honeycomb mirror optics supporter

ZERODUR® glass ceramic made by SCHOTT is an inorganic, non-porous material, made by a process of controlled volume crystallization. It contains a crystallized phase and a rest glass phase which together define the unique properties of this exceptional material. ZERODUR® has an extremely low coefficient of expansion (CTE), which even can become zero or slightly negative in some temperature ranges. Another unique characteristic of ZERODUR® low expansion glass ceramic is its exceptional good homogeneity. Even in large material blocks, the fluctuations of mechanical and thermal properties are nearly not measurable. A good transparency in the range of about 400-2.300nm allows a verification of the inner quality of ZERODUR®. Therefore it can be ensured, that if required, neither bubbles nor inclusions in ZERODUR® glass ceramic are undetected. For further detailed information

Finished block of ZERODUR® glass ceramic

ZERODUR® glass block with drilled holes

In order to request a quotation for a finished part made of original ZERODUR® zero expansion glass ceramics from SCHOTT with custom dimensions, please click the button below:


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Specifications of ZERODUR®



  • Typical transmission of ZERODUR®
  • Refractive index nd = 1,5424 (587,6nm)
  • Abbe number: vd = 56,1
  • Stress optical coefficient K: 3,0 x 10-6 MPa-1
    (at 589,3nm)


  • 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):
  • Total change of length (-50 to +100 °C):
    • < 10 x 10-6/K per length of the part
  • Recommended cooling rate for applications in
    the 130-320 °C temperature range:
    • Small changes of the CTE might occur, if ZERODUR® is cooled down from an operating temperature between 130-320 °C to room temperatuture 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°/h and 6°/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 x 10-6 m2/s (at 20°C)
  • Heat capacity:
    • 0,80 J/(g x 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 x 10-13 (Ohm x cm)
Dielectric Constant
  • 8,0 (1kHz)
  • 7,4 (1 MHz)
Loss Factor tan d
  • 29 x 10-3 (1kHz)
  • 15 x 10-3 (1 MHz)


Surface Quality

For further detailed information, please use our information request form us.


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