Abstract: The present invention provides doped titania-doped silica glass articles having low thermal expansions and low variations in thermal expansion. According to one embodiment of the invention, a titania-doped silica glass article has a titania content of between about 5 wt % and about 9 wt %; a coefficient of thermal expansion of between about ?30 ppb/° C. and about +30 ppb/° C. at a temperature between 15° C. and 30° C.; and a variation in coefficient of thermal expansion of less than about 5 ppb/° C. at a temperature between 15° C and 30° C.

Abstract: Methods, apparatus and precursors for producing substantially water-free silica soot, preforms and glass. The methods and apparatus make substantially water-free fused silica preforms or glass by removing water as a reaction product, removing water from the atmosphere, removing water from the transport process, or combinations thereof. In a first embodiment, substantially water-free soot, preforms or glass are achieved by using a hydrogen-free fuel, such as carbon monoxide, in the deposition process. In another embodiment, a soot producing burner has parameters that enable operation on a substantially hydrogen-free fuel. End burners, which minimize water production, are also described. Such water-free methods are useful in depositing fluorine-doped soot because of the low water present and the efficiency in which fluorine is incorporated. In another embodiment, glassy barrier layer methods and apparatus are described for minimizing dopant migration, especially fluorine.

Abstract: A method for impregnating porous monolith supports with catalytically active materials is disclosed. The impregnation is carried out at a temperature which substantially reduces chemisorption rates such that reactions between the monolith substrate and catalytically active materials in the catalyst solution are minimized. The process can be completed in a practical time that allows for unit selectivity of the weight ratio of catalytically active materials in the substrate to the weight ratio of catalytically active materials in the catalyst solution.

Abstract: Methods, apparatus and precursors for producing substantially water-free silica soot, preforms and glass. The methods and apparatus make substantially water-free fused silica preforms or glass by removing water as a reaction product, removing water from the atmosphere, removing water from the transport process, or combinations thereof. In a first embodiment, substantially water-free soot, preforms or glass are achieved by using a hydrogen-free fuel, such as carbon monoxide, in the deposition process. In another embodiment, a soot producing burner has parameters that enable operation on a substantially hydrogen-free fuel. End burners, which minimize water production, are also described. Such water-free methods are useful in depositing fluorine-doped soot because of the low water present and the efficiency in which fluorine is incorporated. In another embodiment, glassy barrier layer methods and apparatus are described for minimizing dopant migration, especially fluorine.

Abstract: The present invention provides doped titania-doped silica glass articles having low thermal expansions and low variations in thermal expansion. According to one embodiment of the invention, a titania-doped silica glass article has a titania content of between about 5 wt % and about 9 wt %; a coefficient of thermal expansion of between about ?30 ppb/° C. and about +30 ppb/° C. at a temperature between 15° C. and 30° C.; and a variation in coefficient of thermal expansion of less than about 5 ppb/° C. at a temperature between 15° C. and 30° C.