| 摘要 |
<p>A fused quartz glass comprising OH in a content of 5 ppm or less and Li, Na, K, Mg, Ca and Cu each in a content of less than 0.1 ppm, exhibiting an internal transmittance, as measured at a thickness of 10 mm with respect to ultraviolet radiation of 245 nm wavelength, of 95% or greater. Preferably, the fused quartz glass exhibits a viscosity coefficient of 1011.5 Pa.s or greater at 1215°C, and exhibits a Cu ion diffusion coefficient, as measured in a region from over 20 mum up to 100 mum in a depth from the surface when left in atmosphere at 1050°C for 24 hours, of 1810-10 cm2/sec or below. This fused quartz glass is produced by converting a raw material silica powder to cristobalite and thereafter fusing the same in a nonreducing atmosphere. This fused quartz glass has the properties of being high in the transmittance of ultraviolet ray, visible light and infrared ray, being highly purified, having high heat resistance and being low in the diffusion velocity of metal impurities, so that it is suitable for use as various optical materials, members for semiconductor production, members for liquid crystal production, etc.</p> |
