Zerodur®

Zerodur is a registered trademark of Schott Glass Technologies. It is a glass ceramic with an extremely low thermal expansion coefficient (~0.02 x 10-6/K at 0-50°C). Zerodur is a glass-ceramic composite material and has both an amorphous (vitreous) component and a crystalline component.

Properties

• Nearly zero thermal expansion with outstanding 3D homogeneity
• High internal quality
• Good processing behavior
• Can be polished to a very high accuracy
• Can be coated easily
• Low Helium permeability
• Non-porous
• Good chemical stability

Applications

• Optics: Telescopes, optical cavities etc
• Microlithography: Zerodur is used as a movable mechanical part in wafer stepper and scanner machines to achieve precise and reproducible wafer positioning. Zerodur is an ideal substrate material for reflective optics in the forthcoming EUV lithography due to its almost zero thermal expansion, outstanding homogeneity and good processing behavior.
• Measurement Technology: The extremely low thermal expansion and proven long-term dimensional stability of Zerodur make it an ideal reference standard for measurement instruments.

Zerodur Constants

• Dispersion: (nf - nc) = 0.00967
• Density: 2.53 g/cm3 at 25°C
• Young's Modulus: 9.1 x 109 dynes/mm2
• Poisson Ratio: 0.24
• Specific Heat at 25°C: 0.196 cal/g°C
• Coefficient of thermal expansion (20° to 300°C): 0.05 ± 0.10 x 10-6/°C
• Maximum Temperature: 600°C