High-purity, opaque quartz glass, method for producing same and use thereof

摘要

The high-purity, opaque quartz glass containing 3x106-9x106 of closed cells having an average size of 20-40 mu m per 1 cm3, a ratio of closed cells having sizes of 100 mu m or more to the whole of cells being 1% or less, thereby showing 5% or less of linear transmittance for near infrared rays ( lambda =900 nm) at a thickness of 1 mm is produced by compacting amorphous silica powder having an average particle size of 0.5-10 mu m, in which each of impurities selected from Li, Na, K, Fe, Ti and Al is 1 ppm or less, if any, and sintering the resultant green body at 1730 DEG -1850 DEG C.