Method of making fused silica

In a method for making a virtually non-porous body of high purity, fused silica glass doped with at least one dopant oxide comprising the steps of:

• (a) producing a gas stream containing a halide-free silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO.sub.2 and a compound in vapor form capable of being converted through oxidation or flame hydrolysis to at least one member of the group consisting of P.sub.2 O.sub.5 and a metal oxide which has a metallic component selected from the Groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;
• (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of high purity fused SiO.sub.2 doped with an oxide dopant;
• (c) depositing said amorphous particles onto a support;
• and
• (d) either essentially simultaneously with said deposition or subsequently thereto consolidating said deposit of amorphous particles into a virtually non-porous body of high purity fused silica;
• the improvement comprising utilizing as the halide-free, silicon-containing compound an organosilicon-R compound in vapor form selected from the group consisting of organosilicon-nitrogen compounds having a Si--N--Si structure, siloxasilazanes having a basic Si--N--Si--O--Si structure, and mixtures thereof having the following properties;
• (1) a Si--R bond dissociation energy that is no higher than the dissociation energy of the Si--O bond;
• (2) a boiling point no higher than 350.degree. C., and
• (3) which, upon pyrolysis and/or hydrolysis, will produce decomposition products beside SiO.sub.2 which are non-toxic.

In a method for making optical waveguide fibers of high purity fused silica glass through the outside vapor deposition process comprising the steps of:

• (a) producing a gas stream containing a halide-free silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO.sub.2 ;
• (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of high purity fused SiO.sub.2 ;
• (c) depositing said amorphous particles onto a mandrel;
• (d) consolidating said deposit of amorphous particles into a non-porous, transparent glass body of high purity fused silica;
• and
• (e) drawing optical waveguide fiber from said body;
• the improvement comprising utilizing as the halide-free silicon-containing compound an organosilicon-R compound in vapor form selected from the group consisting of organosilicon-nitrogen compounds having a basic Si--N--Si structure, siloxasilazanes having a basic Si--N--Si--O--Si structure, and mixtures thereof having the following properties;
• (1) a Si--R bond dissociation energy that is no higher than the dissociation energy of the Si--O bond;
• (2) a boiling point no higher than 350.degree. C.;
• and
• (3) which, upon pyrolysis and/or hydrolysis, will produce decomposition products beside SiO.sub.2 which are non-toxic.

In a method for making waveguide fibers of high purity fused silica glass doped with an oxide dopant through the outside vapor deposition process comprising the steps of:

• (a) producing a gas stream containing a halide-free silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO.sub.2 and a compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to at least one member of the group consisting of P.sub.2 O.sub.5 and a metal oxide which has a metallic component selected from the Groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and the rare earth series of the Periodic Table;
• (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of high purity fused SiO.sub.2 doped with an oxide dopant;
• (c) depositing said amorphous particles onto a mandrel;
• (d) consolidating said deposit of amorphous particles into a non-porous, transparent glass body;
• and
• (e) drawing optical waveguide fiber from said body;
• the improvement comprising utilizing as the halide-free, silicon-containing compound an organosilicon-R compound in vapor form selected from the group consisting of organosilicon-nitrogen compounds having a basic Si--N--Si structure, siloxasilazanes having a basic Si--N--Si--O--Si structure, and mixtures thereof having the following properties;
• (1) a Si--R bond dissociation energy that is no higher than the dissociation energy of the Si--O bond;
• (2) a boiling point no higher than 350.degree. C.;
• and
• (3) which, upon pyrolysis and/or hydrolysis, will produce decomposition products beside SiO.sub.2 which are non-toxic.

In a method for making optical waveguide fibers of high purity fused silica glass through the axial vapor deposition process comprising the steps of:

• (a) producing a gas stream containing a halide-free silicon-containing compound in vapor form capable of being converted through thermal decomposition with oxidation or flame hydrolysis to SiO.sub.2 ;
• (b) passing said gas stream into the flame of a combustion burner to form amorphous particles of high purity fused SiO.sub.2 ;
• (c) depositing said amorphous particles onto a bait tube;
• (d) consolidating said deposit of amorphous particles into a non-porous, transparent glass body of high purity fused silica;
• and
• (e) drawing optical waveguide fiber from said body;
• the improvement comprising utilizing as the halide-free, silicon-containing compound an organosilicon-oxygen compound in vapor form selected from the group consisting of organosilicon-nitrogen compounds having a basic Si--N--Si structure, siloxasilazanes having a basic Si--N--Si--O--Si structure, and mixtures thereof having the following properties;
• (1) a Si--R bond dissociation energy that is no higher than the dissociation energy of the Si--O bond;
• (2) a boiling point no higher than 350.degree. C.;
• and
• (3) which, upon pyrolysis and/or hydrolysis, will produce decomposition products beside SiO.sub.2 which are non-toxic.