Preparation of high purity silica

We describe an economical self-sustaining process for making high purity bulk silica boules by flame oxidation of silane, SiH 4. We also report a simple procedure for converting the bulk silica boules into rod stock, which is a useful shape for certain applications such as preparing optical fiber preforms. The silica produced by this process has a surprisingly low water content, 59 ppm, which is over an order of magnitude less than found in commercially available silica produced by flame techniques. The high purity of our silica, which was made with house gas in an uncontrolled environment, can be inferred from its low measured optical absorption 5.4 dB/km, at a wavelength of 1.06μ.