| 摘要 |
A process for producing a high-purity optical silica preform, comprising (a) vaporization of an organosilicon compound; (b) thermal decomposition of the said organosilicon compound in the vapour state, to give amorphous fused silica particles; (c) deposition of the said amorphous fused silica particles on a support, in which the said organosilicon compound has the formula (I) <CHEM> in which R1,R2 and R3 are each, independently, hydrogen, methyl, ethyl, propyl, isopropyl or a group of formula -Si-(R5R6R7), where R5, R6 and R7 are each, independently, methyl, ethyl, propyl or isopropyl, and R4 is a group of formula -(CH2)m-Si(R5R6R7), where R5, R6 and R7 are as defined above and m is an integer between 0 and 3. Preferably, at least two of the groups R1, R2 and R3 are other than hydrogen. Among these compounds, the ones which are preferred are those which are liquid at room temperature, those with a boiling point of less than about 140 DEG C, preferably between about 70 DEG C and about 140 DEG C, being particularly preferred. Examples of compounds of formula (I) are: (CH3)3-Si-Si-(CH3)3 (hexamethyldisilane) Ä(CH3)3-SiÜ3-Si-H (tris(trimethylsilyl)silane) (CH3)3-Si-CH2-Si-(CH3)3 (bis(trimethylsilyl)methane) Preferably, the compound of formula (I) is hexamethyldisilane. |
