| 摘要 |
The invention relates to a glass and a glass-ceramic comprising beta-quartz and/or keatite solid solutions, and to a process for their production, and to their use as substrate material for coating. Glass-ceramic comprising beta-quartz and/or keatite solid solutions with a surface roughness without polishing of Ra<50 nm, a thermal expansion in the temperature range between 20° C. and 300° C. of <1.2.10<-6>/K, a transmission in the near infrared region at 1050 nm of >85% for a 4 mm thickness, and a composition in % by weight, based on the total composition, containing:and, if appropriate, at least one refining agent, such as As2O3, Sb2O3, SnO2, CeO2, sulphate and chloride compounds.
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