Abstract: Silane is removed from the exhaust gas of silicon CVD reactors by injecting a stoichiometric excess of halogen to produce halosilanes which are hydrolyzed in water. The removal method permits the use of small individual reactors at each CVD reactor site and eliminates the collection and transport of hazardous gases to a central disposal site for destruction.

Abstract: A method for producing uranium oxide includes combining uranium oxyfluoride and silicon and heating the combination below the vapor point of the uranium oxyfluoride to sufficiently react the uranium oxyfluoride and silicon to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound, e.g. silicon tetrafluoride.

Abstract: A high quality non-single-crystal silicon alloy material including regions of intermediate range order (IRO) silicon alloy material up to but not including the volume percentage required to form a percolation path within the material. The remainder of the material being either amorphous or a mixture of amorphous and microcrystalline materials. The materials were prepared by CVD using differing amounts of hydrogen dilution to produce materials containing differing amounts of IRO material. Preferably the material includes at least 8 volume percent of IRO material.

Abstract: Microporous fluorinated silica agglomerates are disclosed and their method of preparation from a reaction of colloidal silica of small particle sizes with an alkylamine (or a hindered amine) and hydrofluoric acid or with alkylammonium fluoride, under convenient laboratory conditions at an atmospheric pressure. The agglomerate is useful to interact with dispersants surrounding inkjet ink pigment particles.

Abstract: A method for producing silicon tetrafluoride includes combining uranium oxyfluoride and silicon dioxide; heating the combination below the melting point of the uranium oxyfluoride to sufficiently react the uranium oxyfluoride and the silicon dioxide to produce non-radioactive silicon tetrafluoride and an oxide of uranium; and removing the silicon tetrafluoride.

Abstract: A process for reacting a zirconia-based material comprises reacting, in a reaction step, plasma dissociated zircon with aqueous hydrogen fluoride to produce a soluble fluoro zirconic acid compound.

Abstract: Compounds containing a tetradecachlorocyclohexasilane dianion are prepared by contacting trichlorosilane with a reagent composition comprising a tertiary polyamine. The compound ?pedeta.SiH.sub.2 Cl.sup.+1 !.sub.2 ?Si.sub.6 Cl.sub.14.sup.-2 ! wherein pedeta is N,N,N',N",N"-pentaethyldiethylenetriamine is prepared by contacting trichlorosilane with pedeta. The compound ?Ph.sub.4 P.sup.+1 !.sub.2 ?Si.sub.6 Cl.sub.14.sup.-2 ! is prepared by contacting trichlorosilane with a mixture of N,N,N',N'-tetraethylethylenediamine and triphenylphosphonium chloride. The tetradecachlorocyclohexasilane dianion can be chemically reduced to cyclohexasilane, a compound useful in the deposition of amorphous silicon films. The tetradecachlorcyclohexasilane dianion can also be contacted with a Grignard reagent to form a dodecaorganocyclohexasilane.

Abstract: A process suitable for producing high purity alkaline earth fluoride product is disclosed which involves (a) mixing (i) MgO, CaO, BaO, Mg(OH).sub.2, Ca(OH).sub.2, and/or Ba(OH).sub.2, (ii) NaOH, KOH and/or NH.sub.4 OH, and (iii) water, to form an aqueous slurry having a temperature of at least 20.degree. C. and an aqueous phase pH of at least 13; (b) adding fluosilicic acid, optionally adding additional water and optionally adding additional NaOH, KOH and/or NH.sub.4 OH to the slurry of (a) at a rate which maintains an aqueous phase pH of 11 or above, and in an amount to provide a molar ratio of Si: (Mg, Ca, and Ba) of at least 1:3.3, a molar ratio of (Na, K, and NH.sub.4):Si of at least 2:1, and a molar ratio of water:Si of at least 20:1, and to obtain a precipitate comprising an alkaline earth fluoride (MgF.sub.2, CaF.sub.2 and/or BaF.sub.2), and an aqueous solution of a soluble silicon anionic compound; and (c) recovering the alkaline earth fluoride product.

Abstract: A method for producing uranium oxide includes combining uranium tetrafluoride, silicon and a gaseous anhydrous oxidizing agent having a lower thermodynamic stability than any oxide of uranium produced; heating the combination below the vapor point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride, silicon and the oxidizing agent to produce uranium oxide and a non-radioactive fluorine compound; and removing the fluorine compound.

Abstract: A method for producing silicon tetrafluoride includes combining uranium tetrafluoride and silicon dioxide; heating the combination below the melting point of the uranium tetrafluoride to sufficiently react the uranium tetrafluoride and the silicon dioxide to produce non-radioactive silicon tetrafluoride and an oxide of uranium; and removing the silicon tetrafluoride.

Abstract: The present invention relates to catalyst supports and improvements thereof for use with supported activators and supported transition metal catalyst systems. The invention specifically involves reacting a carrier containing reactive functionalities, e.g., hydroxyl containing silica, with halogenated organic compounds, e.g., fluorosubstituted phenols. The reaction is preferably carried out in the presence of a base. The reaction consumes undesired functionalities on the support to provide a halogenated support which is suitable for activators and catalytic precursors which are adversely affected by functionalities typically found on supports. The supported activators or catalytic precursors are prepared by contacting the precursors or activators with the halogenated support.

Abstract: A process for producing trichlorosilane by reacting silicon with hydrogen chloride, which comprises bringing at least one silane compound selected from the group consisting of dichlorosilane, monochlorosilane and monosilane into contact with silicon during or prior to a reaction between silicon and hydrogen chloride to remove silicon oxide on the surface of silicon, thereby improving the reactivity of silicon with hydrogen chloride to produce silicon trichloride stably. Further, an alkali metal compound is co-present in the reaction between silicon and hydrogen chloride to suppress the production of silicon tetrachloride, thereby making it possible to produce trichlorosilane at a high selectivity.

Abstract: An (alkylhalo)silane is prepared by using a fluidized bed reactor equipped with a feed line for reactant gas and a delivery line for product gas, charging the reactor with a contact mass comprising metallic silicon powder and a copper catalyst, and feeding a reactant gas containing an alkyl halide through the feed line into the reactor whereby the silane is formed by direct synthesis. A dust collector is connected to the delivery line for collecting the contact mass carried over with the product gas, which is fed back to the reactor. The feed of the reactant gas is controlled such that a linear velocity multiplied by a density may range from 0.2-2 kg/m.sup.2 .multidot.sec.

Abstract: Highly pure disilicon hexafluoride is synthesized by a process in which a suspension of a fluorination agent is made by dispersing this fluorination agent in an oxybenzene compound as a solvent and disilicon hexachloride is dripped in the suspension to be caused to react with the fluorination agent in nitrogen gas flows under atmospheric pressure, the oxybenzene being expressed by a following formula: ##STR1## (where each of R.sub.1 and R.sub.2 is an alkyl group alternatively having one or more substituents; carbon numbers summed up by R.sub.1 and R.sub.2 are equal to at least 2; and m.gtoreq.1 and n.gtoreq.0).

Abstract: A process for treating dissociated zircon comprises reacting dissociated zircon with gaseous hydrogen fluoride at an elevated reaction temperature. The reaction temperature is controlled to obtain at least one desired zirconium-based compound and at least one desired silicon-based compound.

Abstract: The present invention relates to fluorinated surfaces which exhibit sufficient hydrophilicity and sufficient electropositivity to bind DNA from a suspension containing DNA and permit elution of the DNA from the surface. Generally, the hydrophilic and electropositive characteristics are expressed at the fluorinated surface. Preferred fluorinated surfaces of the present invention include fluorinated Al(OH).sub.3, fluorinated SiO.sub.2 and fluorinated Celite. The fluorinated surfaces of the present invention are particularly useful in processes for purification of DNA from other cellular components. In these processes, a suspension of cellular components is placed in contact with the fluorinated surface, the fluorinated surface is washed to remove all cellular components other than DNA which are bound to the surface, and the bound DNA is eluted from the surface. Lower concentrations of chaotrope in the binding buffer are needed to bind DNA to the fluorinated surfaces.

Abstract: The present invention relates to fluorinated surfaces which exhibit sufficient hydrophilicity and sufficient electropositivity to bind DNA from a suspension containing DNA and permit elution of the DNA from the surface. Generally, the hydrophilic and electropositive characteristics are expressed at the fluorinated surface. Preferred fluorinated surfaces of the present invention include fluorinated Al(OH).sub.3, fluorinated SiO.sub.2 and fluorinated Celite. The fluorinated surfaces of the present invention are particularly useful in processes for purification of DNA from other cellular components. In these processes, a suspension of cellular components is placed in contact with the fluorinated surface, the fluorinated surface is washed to remove all cellular components other than DNA which are bound to the surface, and the bound DNA is eluted from the surface. Lower concentrations of chaotrope in the binding buffer are needed to bind DNA to the fluorinated surfaces.

Abstract: Water-soluble film-forming inorganic compounds having a specific gravity of 1.1 or more and capable of being formed into a film at ordinary temperature or by heating. The compounds are formed by a reaction of a metal, a hydroxide of an alkali metal, and hydrofluoric acid or boric acid and their salts or their submineral acid salts. The water-soluble film-forming inorganic compounds are superior in refractory, heat-resistant and heat-insulating properties, also have rust-inhibitory properties. The compounds are useful as heat-resistant adhesives in fireproof and heat-resistant layered composites made of metal, wood, and the like. A process of coating materials with a layer of these compounds is also provided.

Abstract: Radioactive metal is recovered from solid oxides of the metal by exposing the oxide to a cocurrent flow of a first acid solution in a first contactor to form partially reacted oxides and a solution containing the metal. The first solution containing the metal is drawn off and the partially reacted oxides are passed through a countercurrent flow of a second acid solution in a second contactor to form reaction residues and a second solution containing the metal. The second solution containing the metal is drawn off and the reaction residues are passed through a countercurrent flow of wash water in a third contactor. The reaction residues are then separated from the wash water and dried.

Abstract: Quartz glass obtained by flame-hydrolyzing a glass-forming raw material to obtain fine particles of quartz glass, having the fine particles of quartz glass deposited and grown on a substrate to obtain a porous quartz glass product and heating the porous quartz glass product to obtain a transparent quartz glass product, which has an OH content of not more than 10 ppm and a halogen content of at least 400 ppm and which contains hydrogen.

Abstract: Fluorine in the form of fluoride is removed from phosphoric acid having an initial phosphate concentration of less than about 50 percent by determining the concentration of fluoride to be removed from the acid and the concentration of silicon in the acid. Silica is added to the acid in an amount sufficient that the molar ratio of fluoride to be removed from the acid to silicon in the acid is about 6. The acid is concentrated to a final phosphate concentration of greater than about 50 percent, whereupon fluoride is reacted to fluosilicic acid. By maintaining the indicated concentration ratio of fluoride to be removed and silicon, fouling of condenser and scrubber components with deposited silica is avoided.

Abstract: A method for rendering asbestos in an asbestos-containing material harmless comprises wetting the material with an aqueous solution containing about 1 to 25% by weight of an organic acid, such as trifluoroacetic acid and at least 1% by weight of a source of fluoride ions, such as ammonium fluoride The acid hydrolyses the magnesium oxide units in asbestos while the fluoride ions attack the interleaved silica layers in the crystal structure of asbestos, thereby destroying the fibrous nature of the asbestos. Wetting with the solutions also facilitates the removal of asbestos-containing material from the substrate on which it is installed.

Abstract: A process for hydrofluoric acid digestion of inorganic silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride comprises the initial step of reacting the matrix material with hydrofluoric acid, to form silicon tetrafluoride gas and a solution/slurry containing aluminum fluoride, undigested oxides, and additional soluble and insoluble fluoride materials. The silicon tetrafluoride gas is purified of contaminants by condensing out impurities in cold traps and reacted with aqueous sodium fluoride to form a solution/slurry of fluorosilicate salt which is delivered to a filter press to separate sodium fluorosilicate powder from the solution/slurry. The sodium fluorosilicate powder is dried and delivered to a kiln at a temperature of about 600.degree. C. to 650.degree. C. to form substantially pure silicon tetrafluoride gas and sodium fluoride powder for collection.

Abstract: Water-soluble film-forming inorganic compounds having a specific gravity of 1.1 or more and capable of being formed into a film at ordinary temperature or by heating. The compounds are formed by a reaction of a metal, a hydroxide of an alkali metal, and hydrofluoric acid or boric acid and their salts or their submineral acid salts. The water-soluble film-forming inorganic compounds are superior in refractory, heat-resistant and heat-insulating properties, also have rust-inhibitory properties. The compounds are useful as heat-resistant adhesives in fireproof and heat-resistant layered composites made of metal, wood, and the like. A process of coating materials with a layer of these compounds is also provided.

Abstract: This invention relates to a process for the production of a usable or storable product with a low susceptibility to elutriation by water. This product is produced from residues containing halides obtained from a waste gas cleaning process. The halide containing residues as components of a crude dust having a CaO/SiO.sub.2 ratio between 1.7 and 3.4, are subjected to a thermal treatment to produce chlorosilicates. The waste gases formed during the thermal treatment for chlorosilicate production are subjected to a preliminary cleaning, and are then transported to the waste gas cleaning system of a refuse incineration plant. The residues occurring during the preliminary cleaning can be added to the crude dust.

Abstract: Titaniferous solid containing titanium (IV) oxide, for example ilmenite, is reacted with silicon tetrafluoride gas at 800.degree. C. or more and at a pressure of at least 1 atmosphere to produce titanium tetrafluoride vapor and silica. The vapor is rapidly removed from the reaction zone, preferably by rapid cooling to solid titanium tetrafluoride, at a sufficient distance from the reaction zone so as not to quench the reaction. The titanium tetrafluoride may be hydrolysed to produce titanium dioxide and hydrogen fluoride which is combined with silica to regenerate silicon tetrafluoride. It is preferred to pretreat the titaniferous solid by grinding and then roasting at 700.degree. C. to 750.degree. C. in air. Products of the reaction may be separated and purified by condensation and resublimation.

Abstract: An improved halogenator process and system is provided which significantly and economically decreases the level of impurities in the processing of various refractory metals and their halides and particularly hafnium tetrachloride which is condensed from gases produced by the chlorination of Zircon.

Abstract: Surfaces of silica-containing materials, such as the inner walls of silica capillaries, used in chromatographic, particularly electrophoretic, separations are coated with an organic polymer layer to reduce or eliminate surface charges. The layer is applied by first converting the silanol groups on the surface to silicon halide groups, then reacting these groups with an organometallic reagent having a terminal ethenyl moiety, preferably vinyl or allyl lithium or a vinyl or allyl magnesium halide, to convert the silicon halide groups to Si--R groups where the R retains the terminal ethenyl moiety, and finally reacting these ethenyl groups newly attached to the surface with a neutral organic monomer in an addition polymerization reaction to form a monomolecular noncrosslinked polymer layer over the surface. The resulting polymer layer is linked to the silica directly through a Si--C bond which is stable over a wide range of pH conditions.

Abstract: A vapor stream from a sand chlorinator containing principally zirconium tetrachloride, hafnium tetrachloride and silicon tetrachloride contaminated with ferric chloride is purified by cooling the vapor to a temperature of about 335.degree. C. to about 600.degree. C. The cooled vapors flow through a gaseous diffusion separative barrier where a silicon tetrachloride vapor stream contaminated with metal chlorides flows from the separative barrier as a "fast" stream; ferric chloride is adsorbed by the separative barrier; and a vapor stream principally containing zirconium tetrachloride, hafnium tetrachloride and silicon tetrachloride is screened by the separative barrier.

Abstract: A process for the dismutation of chlorosilanes is disclosed in which the latter are in the gas phase for 0.01-100 sec. at 55.degree.-100.degree. C. or in the liquid phase for 1-1000 sec. at 25.degree.-55.degree. C. conducted in the presence of a catalyst, which is either unformed or is present in the form of spherical pellets, and which consists of one of four different organopolysiloxane compounds, optionally cross-linked, which essentially carry an amino or ammonium group as a functional group.

Abstract: Silicon difluoride is produced by the reduction of silicon tetrafluoride in a plasma torch under argon atmosphere. Instead of the usual reducing agents finely divided silicon has now been used as a reducing agent.

Abstract: Process for the production of anhydrous calcium fluosilicate from anhydrous calcium chloride and impure fluosilicic acid solution, a by-product of the acid treatment of phosphorus ores containing fluorine, characterized in that a calcium fluosilicate dihydrate is precipitated at low temperature and quantitatively by suitable adjustment of the fluosilicic acid concentration and the molar ratio CaCl.sub.2 /H.sub.2 SiF.sub.6 and that after filtration, washing and drying of the precipitate, an anhydrous calcium fluosilicate which can be easily decomposed by heat treatment is obtained to restore calcium fluoride and silicon tetrafluoride suitable for the manufacture of pure hydrofluoric acid and fluosilicic acid.For gravimetric concentrations of H.sub.2 SiF.sub.6 >25% and molar concentration ratios CaCl.sub.2 /H.sub.2 SiF.sub.6 between 2 and 5, the yields of the anhydrous calcium fluosilicate obtained are greater than 94%.

Abstract: Water-soluble film-forming inorganic compounds having a specific gravity of 1.1 or more and capable of being formed into a film at ordinary temperature or by heating. The compounds are formed by a reaction of a metal, a hydroxide of an alkali metal, and hydrofluoric acid or boric acid and their salts or their submineral acid salts. The water-soluble film-forming inorganic compounds are superior in refractory, heat-resistant and heat-insulating properties, also have rust-inhibitory properties. The compounds are useful as heat-resistant adhesives in fireproof and heat-resistant layered composites made of metal, wood, and the like. A process of coating materials with a layer of these compounds is also provided.

Abstract: The present invention produces very stable, covalently bonded separation substrates for separations application such as liquid and gas chromatography as well as capillary zone electrophoresis. An intermediate substrate is prepared which has hydride species on the substrate surface. These hydrides preferably are further derivatized by the catalytic addition of organic compounds bearing a terminal vinyl group. The final surface modification contains closely packed, direct carbon linkages that are stable.

Abstract: A method of producing submicron nonagglomerated particles in a single stage reactor includes introducing a reactant or mixture of reactants at one end while varying the temperature along the reactor to initiate reactions at a low rate. As homogeneously small numbers of seed particles generated in the initial section of the reactor progress through the reactor, the reaction is gradually accelerated through programmed increases in temperature along the length of the reactor to promote particle growth by chemical vapor deposition while minimizing agglomerate formation by maintaining a sufficiently low number concentration of particles in the reactor such that coagulation is inhibited within the residence time of particles in the reactor. The maximum temperature and minimum residence time is defined by a combination of temperature and residence time that is necessary to bring the reaction to completion.

Abstract: The present application relates to a method for production of trichloromonosilane in a fluidized bed reactor by reaction of silicon powder and HCl at a temperature between 280.degree. and 300.degree. C. wherein silicon powder which has been produced by gas atomization of molten silicon is used. The gas atomized silicon powder has a preferred particle size between 1 and 1000 .mu.m.

Abstract: A method for producing high purity silica and ammonium fluoride from silicon tetrafluoride-containing gas wherein silicon tetrafluoride-containing gas from the acidulation of phosphorus-containing rock is recovered and the liquid entrainment is separated from the gas. The recovered gas is converted to an ammonium fluosilicate solution and is ammoniated to produce high purity silica and ammonium fluoride. The recovered gas can be converted to an ammonium fluosilicate solution either by absorbing the gas directly in a solution of ammonium fluoride or by first absorbing the gas in water to produce fluosilicic acid and then reacting the fluosilicic acid with ammonia or ammonium fluoride.

Abstract: The present invention provides a coating for electrodes for use in electrochemical cells having an electrochemically active species and an electrolyte. The coating contains active species material and is selectively permeable allowing for the diffusion of the active species through the coating during operation of the cell while providing a substantially impervious barrier to the electrolyte. The coating optionally further includes a polymer layer over the active species containing coating or layer for maintaining the mechanical integrity of the active species layer.Electrodes utilizing the coatings described herein may be used in primary and secondary cells over a wide range of operating temperatures to deliver better electrochemical performance even at room temperature.Methods of making the coating and an apparatus for performing these methods on a continuous basis are disclosed.A novel composition of matter is disclosed comprising lithium, silicon, and fluorine prepared by exposing lithium metal to SiF.sub.

Abstract: A process is described for increasing the percentage of silicon tetrachloride during the reaction of hydrogen chloride or a mixture of hydrogen chloride and chlorine with substances containing metallic silicon. In this process the chlorosilanes are exposed to a temperature ranging between 300.degree. C. and 1400.degree. C.

Abstract: A process for producing hydrofluoric acid from SiF.sub.6.sup.2- in a wastewater is disclosed. The process is carried out by(i) combining (NH.sub.4).sub.2 SO.sub.4, at a pH high enough such that the sulfate is in its divalent state, with SiF.sub.6.sup.2- from said wastewater in an amount in excess of that stoichiometrically required to form (NH.sub.4).sub.2 SiF.sub.6 as follows:(NH.sub.4).sub.2 SO.sub.4 +SiF.sub.6.sup.2- .fwdarw.(NH.sub.4).sub.2 SiF.sub.6 +SO.sub.4.sup.2-(ii) concentrating a solution including (NH.sub.4).sub.2 SiF.sub.6 and excess (NH.sub.4).sub.2 SO.sub.4 to precipitate and separate (NH.sub.4).sub.2 SiF.sub.6 of high purity therefrom;(iii) re-solubilizing the (NH.sub.4).sub.2 SiF.sub.6 for reaction with NH.sub.4 OH to form NH.sub.4 F liquor and precipitated Si(OH).sub.4 ;(iv) separating the NH.sub.4 F liquor from the precipitated Si(OH).sub.4 ;(v) reacting the NH.sub.4 F with water to form precipitated NH.sub.4 F.multidot.HF and ammonia gas;(vi) reacting NH.sub.4 F.multidot.

Abstract: A process for producing chlorides by the chlorination of a material selected from the group consisting of aluminous materials and metal and metalloid oxides in the presence of a reductant. The method comprises calcining a carbonaceous material with added steam to oxidize substantially all precursors of chlorinated hydrocarbons and to form a reductant; and chlorinating a material selected from the group consisting of aluminous materials and metal oxides in the presence of the reductant.

Abstract: The present invention is directed to a method for synthesizing fluorine-containing, aluminosilicate crystals having a stoichiometry approximating that of topaz. The method comprises three basic steps:(1) vapors of a readily-oxidizable compound of silicon and of a readily-oxidizable compound of aluminum and fluorine are passed to a flame oxidation burner;(2) amorphous fluorine-containing, aluminosilicate particles resulting from the combustion of those gases are collected; and(3) the collected particles are sintered into an integral body at a temperature between about 650.degree.-925.degree. C.

Abstract: A ZrO.sub.2 powder of very fine particle size adapted especially for the making of high density ceramics is produced by chlorinating a zirconium source material, such as zircon sand, to produce crude ZrCl.sub.4 solids; the solids are dissolved to form a ZrOCl.sub.2 solution from which ZrOCl.sub.2 crystals are precipitated; the crystals are dried and milled to a desired particle size; and the crystal particles are subjected to direct oxidation under controlled conditions to produce a very fine ZrO.sub.2 powder especially adapted to the making of high density ceramics.

Abstract: Residual silicone from direct process manufacture of chlorosilanes is stabilized for transportation and disposal.

Abstract: The present invention provides a coating for electrodes for use in electrochemical cells having an electrochemically active species and an electrolyte. The coating contains active species material and is selectively permeable allowing for the diffusion of the active species through the coating during operation of the cell while providing a substantially impervious barrier to the electrolyte. The coating optionally further includes a polymer layer over the active species containing coating or layer for maintaining the mechanical integrity of the active species layer.Electrodes utilizing the coatings described herein may be used in primary and secondary cells over a wide range of operating temperatures to deliver better electrochemical performance even at room temperature.Methods of making the coating and an apparatus for performing these methods on a continuous basis are disclosed.A novel composition of matter is disclosed comprising lithium, silicon, and fluorine prepared by exposing lithium metal to SiF.sub.

Abstract: Chloropolysilanes can be produced in high yield without forming solid waste materials by contacting silicon materials with chlorine at a temperature of 140.degree..about.300.degree. C. in the presence of copper compound or a mixture thereof.

Abstract: A silica-containing material such as silica sand, a carbonized biomass or biomass ash is converted into carbon tetrachloride by reaction with chlorine gas at an elevated temperature in the presence of a carbonaceous material such as coke, and sulfur or a sulfur compound. The reaction may be suitably performed in the further presence of a potassium compound.

Abstract: There is here disclosed a ladder polysilane represented by the general formula (I): ##STR1## wherein n is a positive integer, and R is a halogen atom, a hydrogen atom, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group or an alkoxy group having 20 or less carbon atoms, and the alkyl, alkenyl, aryl or alkoxy group may contain a functional group such as --COOH, --SO.sub.3 H, --NH.sub.2, --NO.sub.2, --NCO, --F, --Cl, --BR, --I or --OH. In addition, a method for preparing the aforesaid ladder polysilane is also disclosed here.

Abstract: Incorporation of fluorine into a porous silica body, such as an unsintered body produced by a sol-gel method, by VAD or OVPO, reduces or eliminates bubble or pore formation upon re-heating of the glass formed by sintering of the porous material. Effective fluorine concentrations are between 0.01 and 5% by weight. The invention can be used advantageously in producing preforms and optical fiber.

Abstract: Trichlorosilane, SiHCl.sub.3, is facilely prepared by (i) thermally reducing silicon tetrachloride, SiCl.sub.4, with hydrogen to produce reaction admixture comprising SiHCl.sub.3 and hydrochloric acid, said thermal reduction being carried out in a thermal plasma while tempering the reaction medium with a cooling gas, (ii) reacting said step (i) reaction admixture with elemental silicon at a temperature of from about 250.degree. to 350.degree. C. to produce SiHCl.sub.3 and hydrogen therefrom, and thence (iii) separating (iiia) the plasma-creating, hydrogen and cooling gases, and (iiib) product silicon chlorides therefrom.