Glass-ceramic with specific thermal expansion behavior

摘要

Base-glasses for glass ceramics cotaining h-quartz solid solution crystals, with a maximum relative length variation of 1×10. sup.-5 and a linear thermal expansion coefficient less than 0.1×10. sup.-6 /K, comprise (in weight percent) 50-65 SiO.sub.2, 18-27 Al.sub.2 O. sub.3, 0-10 P.sub.2 O.sub.5,0-1 B.sub.2 O.sub.3, 2.5-4 Li.sub.2 O, 0-2 Na. sub.2 O, 0-2 K.sub.2 O, 0-0.5 MgO, 1-5 ZnO, 1-4 CaO, 1-5 BaO, 0-5 TiO.sub. 2, 0- 3 ZrO.sub.2 and 0-1.5 As.sub.2 O.sub.3.