Patent ID: 6750167
Filing Date: 2004-06-15
Classification: C03C

Abstract:
A crystallized glass, a &bgr;-quartz solid solution or a &bgr;-eucryptite solid solution being precipitated as a main crystal, wherein the crystallized glass has a crystallinity not less than 70 mass %, a crystal grain size not more than 0.5 &mgr;m, substantially no gap or crack presenting at boundaries of crystal grains, and wherein the crystallized glass also has a thermal expansion coefficient being negatively greater than âˆ’10Ã—10âˆ’7/Â° C. within a temperature range of âˆ’40Â° C.Ëœ100Â° C., a hysteresis of the thermal expansion coefficient within the temperature range being not more than 10 ppm, and a temperature dependence of refractive index being not more than 13Ã—10âˆ’6/Â° C.