| 摘要 |
PURPOSE:To obtain the title high-purity artificial quartz crystal having a low content of impurities, especially of Al, and having excellent radioactivity resistance by using specified crystalline silica as the raw material at the time of producing an artificial quartz crystal by hydrothermal growth. CONSTITUTION:When an artificial quartz crystal is produced by hydrothermal growth, amorphous silica contg. <=10ppm of the impurities of the alkali (alkaline earth) metal elements such as Li, Na, K, Mg, and Ca and transition metal elements such as Al, Ti, Cr, Fe, and Cu is impregnated with an aq. soln. (e.g., an aq. NaOH soln.) contg. alkaline compds. selected from Na, K, and Li to increase the crystallization rate and to lower the treating temp. The impregnated silica is then dried to control the content of alkali metal elements to >=5ppm, and then heat-treated preferably at 900-1,600 deg.C to convert the silica to crystalline silica contg. cristobalite. The crystalline silica is used as the raw material. |
