| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing SiO2 , by which high purity SiO2 is produced at a low cost using solid SiO or gaseous SiO. SOLUTION: The high purity SiO2 is produced by heating solid SiO to a temperature of >=1,000 and <=1,730 deg.C so as to decompose it into liquid or solid Si and solid SiO2 , then separating the formed SiO2 from Si present at the lower part and further heating the SiO2 in order to purify. Or, the high purity SiO2 is obtained from purified gaseous SiO by using an oxidizing gas. By these methods, impurities, such as OH, Cl or metal components, adversely affecting the light transmissivity or the viscosity of SiO2 can be removed and it becomes possible to supply SiO2 containing the impurities in a total amount of <=10 ppm at a low cost as a raw material of an optical product such as an optical fiber or a high purity quartz product useful for a semiconductor.
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