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: A method for preparing ultra-pure metal tetrafluorides in which 3d such as Fe impurities are separated from impure material by a combined vaporization-electrolytic separation procedure. Sublimation and distillation methods are disclosed in combination with electrolytic separation by both emf-series displacement (ESD) and direct melt electrolysis (DME).

Abstract: The specification discloses a process for the preparation of ultrapure thorium fluoride (ThF.sub.4) having minimized water content and consequent maximized optical transmission of 10.6 micrometer radiation. First, thorium oxide is reacted with aqueous hydrofluoric acid to form a solid reaction product, which is then dried under controlled heating to form a hydrated thorium fluoride with a predetermined amount of hydration, namely ThF.sub.4.xH.sub.2 O where x is equal to 0.39. The hydrated thorium fluoride is exposed to a reactive atmosphere of hydrofluoric acid vapor and a selected fluoride compound in the gas phase at elevated temperature for a predetermined period of time. The reactive atmosphere removes substantially all of the water and water-derived impurities from the hydrated thorium fluoride to produce ultrapure thorium fluoride which is highly transmissive to 10.6 micrometer radiation.

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: An apparatus and process for growing large single halide crystals that are ultra pure is described. A bicameral apparatus and process is employed in which the crystals are grown in a reactive chamber positioned within an inert chamber. A radial seal is provided on the furnace chamber to facilitate the reaction and maintenance of an inert atmosphere around and about a crystal growth assembly wherein crystals are grown from a melt under a reactive atmosphere.

Abstract: Improved multicomponent fluorozirconate glasses, doped with chlorine, and a process for making them are disclosed that are continuously transmissive in the infrared spectrum.

Abstract: The specification describes a process for depositing a film of controlled composition on a substrate by using a metallo-organic photoresist in which the organic portion is combusted by heating in a reactive atmosphere to leave a residual deposit of a desired substance on the substrate. The film may be formed as a patterned or unpatterned layer. In addition, the residual deposit may be subsequently subjected to a chemical reaction to alter its composition.

Abstract: The specification discloses a process for modifying the environment of active atoms in a selected material by removing impurities from the environment. The material is heated at an elevated temperature in an atmosphere conducive to the formation of atomic oxygen so that the atomic oxygen can react with the atoms and molecules in the environment to remove the impurities in and thus alter selected properties of the material. In a preferred embodiment of the present invention, the lasing efficiency of a neodymium-doped yttrium aluminum garnet crystal is increased by heating the crystal at an elevated temperature in an atmosphere conducive to the formation of atomic oxygen so that the atomic oxygen can react with and remove impurities from the crystal to diminish the color center concentration therein and thus increase the fluorescence yield and lasing efficiency of the crystal.

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.

Abstract: Alkaline earth chloride crystals exhibiting substantially improved physical and optical transmission characteristics are grown from starting powders by a one step Reactive Atmospheric Processing (RAP) method.

Abstract: An improved process for generating nascent bromine through the pyrolytic dissociation of CBr.sub.4 is shown to be applicable to the growth of large single crystals of metal bromides from the melt.

Abstract: A tetrafluoromethane (CF.sub.4) generator and process is disclosed that facilitates the relatively low temperature production of CF.sub.4 gas via controlled decomposition of polytetrafluoroethylene (Teflon) and tetrafluoroethylene (C.sub.2 F.sub.4). CF.sub.4 produced via this process proves to be an excellent OH.sup.- scavenger in the processing and growth of metal fluoride single crystals.

Abstract: Alkali metal halide crystals exhibiting substantially improved physical and optical transmission characteristics are grown from starting powders by a one step Reactive Atmospheric Processing (RAP) method.

Abstract: We have discovered that alkali halides may be purified, particularly of trace anionic and cationic impurities, by scrubbing a melt of the alkali halide with gaseous nascent halogen. The halide radical of the gaseous nascent halogen preferably corresponds to the halide radical of the alkali halide. The purified material may then be used to form single crystals from which laser windows may be produced.

Abstract: Single crystals, useful as laser emission compounds, having the formula ARF.sub.4 wherein A is potassium, sodium, or lithium, and R is holmium, yttrium, erbium, or dysprosium are prepared by a direct congruent melt crystal growth process that yields crystals exhibiting substantially superior physical and chemical characteristics compared to those grown by conventional methods.

Abstract: An invention directed to the preparation of laser windows from halide crystals purified by congruent growth from the melt by a reactive atmospheric processing method is disclosed. Single crystal refractory metal halides, and rare earth halides prepared by this invention can be used to produce laser windows of excellent mechanical, thermal, and optical properties.