Abstract: A precursor material is superoxidized to a superconducting oxide material in an atmosphere containing a reactive component that reacts with and removes hydroxide ion (OH.sup.-), replacing it with peroxide ion (O.sup.-). Preferred reactive components include H.sub.2 O.sub.2, N.sub.2 O, and I.sub.2. The reactive component reacts with and removes hydroxide ion from the precursor material, to reach a higher oxidation state in the superconducting oxide material than possible by oxidation in molecular oxygen. The use of such a reactive component permits both faster oxidation of the precursor material at conventional temperatures and the use of lower temperatures to achieve oxidation.

Abstract: High temperature superconducting oxide materials can be taken to a higher, but stable, state of oxidation by removing H-impurities, such as OH.sup.-, using I.sub.2 /O.sub.2 mixtures in a reactive atmosphere process. A higher T.sub.c and a narrower .DELTA.T-transition result.

Abstract: A novel, solid-state, low-temperature preparation of barium sulfate provides a higher purity material than that obtained by the conventional method of precipitation. The reaction involves heating a barium oxysalt in the presence of at least one sulfur-containing species for a period of time.

Abstract: A superconducting oxide precursor material is prepared by dissolving soluble compounds containing the non-oxygen elements of the oxide in concentrated nitric acid, in which a decomposing agent for the nitrate of the nitric acid selected from urea and sucrose and an oxidizing/reducing agent selected from hydrogen peroxide and ammonium nitrate have also been dissolved. The acid solution is concentrated by heating until the liquid component is pyrolyzed, leaving a superconducting oxide precursor material residue. The precursor material is produced with a relatively high oxidation state, but is normally further oxidized to reach a superconducting state.

Abstract: A fluoride glass is prepared by depositing a solid including a metal fluoride on a heated substrate, from a gaseous mixture of a nonmetallo-organic compound, carbon dioxide, and a source of carbonyl fluoride. The nonmetallo-organic compound contains the metallic cation of the metal fluoride bonded to an organic species through an electronegative element such as oxygen, but not directly to a carbon atom. The carbon dioxide, or optionally another species reactive with carbon to produce a gas, oxidizes solid carbon and other reduction products of the organic compound that could otherwise be present in the deposited metal fluoride to impair optical properties of the fluoride glass. The carbonyl fluoride, supplied by the gas itself or by reactants that produce the gas, reacts with the nonmetallo-organic compound without producing water, which would otherwise degrade the glass purity.

Abstract: Metal sulfides are prepared by reacting a compound of the metal and an oxygen-containing anion, with a source of carbonyl sulfide. The resulting metal sulfide is not contaminated by hydrogen, as in the form of hydroxides, and is suitable for use in photoluminescence and electroluminescence applications. The starting material is preferably a metal oxalate, which may be appropriately doped, and the source of the carbonyl sulfide is preferably a mixture of carbon monoxide and sulfur dioxide (to produce a reducing mode) or a mixture of carbon dioxide and carbon disulfide (to produce an oxidizing mode). Oxyanions that decompose to a produce a nascent oxygen anion, as does the oxalate, are preferred, as they can be reacted to achieve a high conversion rate to the sulfide.

Abstract: A method for preparing compounds of sulfur, selenium, and tellurium includes the formation of the compound from the elements in a closed environment which excludes oxygen, and then the purification of the compound by contacting it with carbon or carbon monoxide. Oxygen, the principal contaminant in conventionally prepared compounds of this group, is excluded from the formation of the compound in the formation step by using a closed reactor, preferably made of vitreous silica. Oxygen in the initial elemental reactants remains in the compound made in this way, and the purification step eliminates the oxygen originally present in the elemental reactants from the compound. Arsenic triselenide made by this approach, glassy and of high purity, is suitable for use in applications requiring infrared transparency.

Abstract: This invention provides a method for the preparation of ultrapure active metal fluorides of increased purity from their metal oxides by reacting an active metal with a predetermined amount of HF(aq) to form a solid reaction product which is dried under controlled heating to form a hydrated fluoride. This hydrated active metal fluoride is then subjected to reactive atmosphere processing comprising hydrofluoric acid vapor in a CO.sub.2 reactive carrier gas and a selected halide compound in the gas phase for a predetermined period of time to further increase anion purity.

Abstract: A catalyst material having a catalyst metal supported on a substrate, wherein the substrate has at least two types of surface atomic sites at which the catalyst metal can reside, and the catalyst metal resides primarily in one of those types of sites. In one catalyst material having platinum supported on an aluminum oxide substrate, the platinum atoms are located predominantly in the substrate sites having the lowest activation energy for catalysis of a chemical reaction. Population of only the low energy type of site is achieved by limiting the platinum content to from about 0.25 to about 1.0 atomic percent.

Abstract: (Nb.sub.1-x Ta.sub.x).sub.2 O.sub.5 ("NTO") is purified of undesirable impurity elements present in small amounts by contacting the NTO in finely divided form to an extraction phase containing chloride, bromide, or iodide ions at a temperature whereat the ions react to remove the impurities into the extraction phase, and then the extraction phase is separated from the finely divided NTO. The process is particularly valuable in removing 3d impurities such as iron and titanium. The process can be carried out by liquid phase extraction, as with an azeotropic aqueous hydrochloric acid extraction from the NTO, or by gas phase reaction, as by reacting carbon tetrachloride with the NTO.

Abstract: This invention provides a method for the preparation of ultrapure active metal fluorides of increased purity from their metal oxides by reacting an active metal with a predetermined amount of HF(aq) to form a solid reaction product which is dried under controlled heating to form a hydrated fluoride. This hydrated active metal fluoride is then subjected to reactive atmosphere processing comprising hydrofluoric acid vapor in a CO.sub.2 reactive carrier gas and a selected fluoride compound in the gas phase for a predetermined period of time to further increase anion purity.

Abstract: A method is disclosed for the growth of single crystals of a binary metal oxides of the formula ABO.sub.3 where A is an alkali or alkaline earth metal, B is at least one element selected from titanium, niobium and tantalum. A mixture comprising the constituent components of the ABO.sub.3 crystal is prepared using a basic oxide or carbonate of A and a stoichiometric excess of an acidic oxide of B. The mixture is heated at an elevated temperature to form a melt and is thereafter exposed to a reactive atmosphere of a mixture of gaseous carbon monoxide and carbon dioxide. Crystal growth from the melt is effected by a top-seeded crystal pulling technique.

Abstract: A process is disclosed for the removal of water and water derived impurities, e.g. OH.sup.-, substitutionally or interstitially incorporated in the structure of crystalline and amorphous materials, more specifically, in metal oxides, e.g. fused silica or aluminum oxide, wherein the material is exposed in powdered form to a gaseous mixture of halogen and carbon monoxide at a predetermined elevated temperature. The mixture of halogen and carbon monoxide reacts to cause the water and OH.sup.- ion concentration in the processed material to be reduced to an extremely low level. Materials purified by the process can be used to produce optical fibers and laser windows of excellent mechanical, thermal and optical properties.

Abstract: The specification discloses new and improved processes for forming water-free metal or non-metal oxide materials, which may then be melted and formed into optical components in vitreous or crystal form, which are free of the hydrogen-impurity absorption in the near infrared wavelength range. In one process, a water-free oxide is prepared by reacting a chosen nonpolar compound containing the desired metal or non-metal with an aprotic oxygen-containing compound to form the oxide as a precipitate in a chosen aprotic nonaqueous liquid solvent which provides a water-free environment during the formation of the oxide, to prevent the inclusion of water and water-derived impurities in the oxide as formed.

Abstract: The specification discloses new and improved processes for forming water-free metal or non-metal oxide materials, which may then be melted and formed into optical components in vitreous or crystal form, which are free of the hydrogen-impurity absorption in the near infrared wavelength range. In one process a water-free oxide is prepared by reacting a chosen organic compound containing oxygen bonded to an atom of the metal or non-metal, with a chosen organic acid anhydride to form an intermediate product which is then decomposed to form the desired oxide and to simultaneously regenerate the organic acid anhydride. The regenerated organic acid anhydride reacts with and removes traces of water and water-derived impurities during the formation of the desired oxide and prevents the inclusion of these impurities in the oxide as formed.

Abstract: The specification discloses a process for forming a water-free rare earth oxychloride powder by exposing a water-containing rare earth oxide powder to a reactive atmosphere of chlorine and oxygen at 1000.degree. C. for 24 hours to remove water impurities from the oxide powder and to simultaneously convert the oxide powder to the oxychloride powder.

Abstract: The specification discloses a process for converting the surface layer of a body of vitreous silica to the more stable crystalline form of silica known as cristobalite. The surface of the body of vitreous silica is exposed to a gas phase reactive atmosphere comprising atomic iodine at a predetermined elevated temperature for a predetermined period of time to convert the surface layer of the vitreous silica to polycrystalline cristobalite and thus passivate and enhance the stability of the treated surface. The disclosed process is particularly useful for forming improved crucibles, such as those used in crystal growth from a melt.

Abstract: The specification discloses a process for forming a coherent, uniform oxide layer on the surface of a selected semiconductor material by heating a wafer of the selected semiconductor material at a temperature of about 750.degree. C. or lower in the presence of a chosen oxygen-containing precursor and a chosen gas phase halogen-containing molecular reactant which reacts with the oxygen-containing precursor to form atomic oxygen. The substrate is heated in the presence of these reactants for a period of time sufficient to enable the atomic oxygen to react with the surface atoms of the wafer and thus form the coherent uniform oxide layer. The temperature of about 750.degree. C. is sufficiently low to avoid adverse effects, such as dopant migration, on the wafer. In a preferred embodiment of the present invention, a coherent, uniform layer of silicon dioxide is formed on the surface of a silicon wafer.

Abstract: The specification discloses a process for forming a coherent, uniform oxide layer on the surface of a selected semiconductor material by heating a wafer of the selected semiconductor material at a predetermined elevated temperature in an atmosphere conducive to the formation of atomic oxygen for a period of time sufficient to enable the atomic oxygen to react with the surface atoms of the wafer and thus form the coherent, uniform oxide layer. The predetermined elevated temperature is sufficiently low to avoid adverse effects, such as dopant migration, on the wafer. In a preferred embodiment of the present invention, a coherent, uniform layer of silicon dioxide is formed on the surface of a silicon wafer by heating the wafer in a vapor mixture of iodine and water at a temperature of 750.degree. C. and one atmosphere of pressure.