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 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 preform for preparation of optical fibers is prepared by inserting a rod of a higher index of refraction fluoride glass into the bore of a hollow cylinder of a lower index of refraction fluoride glass fiber. This preform precursor is processed to collapse the hollow cylinder inwardly to form a composite preform having a high-refractive index core and a low-refractive index casing. The preparing of the glasses and processing to a preform are accomplished in a reactive environment that reacts and removes oxygen and hydrogen containing species from the glass, the reactive environment being, for example, Cl.sub.2, CCl.sub.4, SF.sub.6, BF.sub.3, CF.sub.4, or the decomposition products of a liquefied solid fluorocarbon. The preform is then drawn to an optical fiber.

Abstract: Cylindrical rods of titanium carbide or other refractory material with uniform, high density are prepared by hot pressing plates from powders of the material, with a uniaxial pressing pressure applied to the broad faces of the plate. Bars of square cross section are then cut from the plate and machined to cylindrical rods. The process is particularly suited to the preparation of refractory material preforms to be used in single crystal growth by the float zone method. Titanium carbide rods having a highly uniform density of about 96% that of the theoretical maximum can be readily prepared and then grown into titanium carbide crystals.

Abstract: A method is disclosed for growing thermally unstable ferroelectric materials having the formula MH.sub.2 XO.sub.4, where M is potassium, rubidium, cesium or ammonium; H is hydrogen or deuterium and X is phosphorus or arsenic. The ferroelectric material is heated to melt temperature in a constant volume cylindrical chamber (10) which is moisture-free. Improved crystal formation is accomplished by axially cooling the melt from the bottom end (18) of the chamber by thermal conduction along the chamber longitudinal axis predominantly and only minimally by radial thermal conduction through the sides (16) of the chamber. The axial cooling produces a crystal interface which is flat and perpendicular to the chamber axis and which gradually progresses toward the chamber top to provide uniform growth of a single crystal of ferroelectric material.

Abstract: An apparatus and method pulling a shaped crystalline fiber of a given crystal-forming material from a liquid reservoir of the material. The apparatus includes a vessel in which the liquid material is maintained as a liquid reservoir at a temperature above the melting point or crystal-forming temperature of the material. A die is provided having an inner-tubular surface which includes a crystal shaping portion which is tapered. The liquid flows from the reservoir through the die so that the liquid flows from the narrow end of the shaping portion to the wide end of the shaping portion. The temperature of the liquid crystal growth material is selectively lowered at the top end of the die to form crystalline material which is continually pulled from the crystal-liquid interface.

Abstract: An improvement of the method for preparing cupric ion-free cuprous chloride powder in which copper metal is added to a highly acidified solution of cupric chloride to reduce the cupric ions to cuprous ions and oxidize the copper metal to cuprous ions. The improvement involves applying an electromotive force to the solution by immersing interconnected copper and platinum electrodes in the solution. The electromotive force is applied only after the reduction of cupric ions is near completion. The electromotive force is applied for a sufficient time to insure essentially complete reduction of cupric ions in the solution. Cuprous chloride is then separated from the cupric ion-free solution by evaporation and isolated by conventional techniques to provide an improved cuprous chloride powder product which is essentially free of cupric ions. The electromotive force is also applied during the evaporation of the acidified solution to prevent possible cupric ion formation.

Abstract: This invention provides a method for conversion of congruently melting polycrystalline fibers to single crystal fibers. The method is particularly useful for production of fibers ranging from about 30 .mu.m to about 1,000 .mu.m in diameter, which are capable of infrared (IR) transmission and of functioning in nonlinear optical applications. The polycrystalline fiber is converted to a single crystal fiber by creating a melt zone near one end of said polycrystalline fiber and then causing said melt zone to travel a length of said polycrystalline fiber at least once, so that the fiber continuously melts and recrystallizes into a single crystal along the length so that such length becomes one continuous crystal.In another embodiment of the invention, the method described above is utilized to improve the surface characteristics of a single crystal.

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: 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: 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: Disclosed is a method of producing metal halide and metal chalcogenide crystals for infrared window application which exhibits a high conversion ratio.

Abstract: A process for suppressing the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 waveguide structures by exposing the structures to a Li.sub.2 O-rich environment at sufficient vapor pressure that Li.sub.2 O diffuses into the structure as a compensation process and a solid-solid surface interaction occurs. In one embodiment of the invention, the out-diffusion of Li.sub.2 O from LiNbO.sub.3 and LiTaO.sub.3 crystals into which Ti has been diffused is eliminated by annealing the structure in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3. In a second embodiment, the Li.sub.2 O out-diffusion is partially suppressed by annealing the structure in molten LiNO.sub.3. In a third embodiment of the invention, a waveguide structure comprising a Li.sub.2 O-rich guiding layer is formed by annealing LiNbO.sub.3 or LiTaO.sub.3 crystals in a high purity powder of LiNbO.sub.3 or LiTaO.sub.3, which not only suppresses Li.sub.2 O out-diffusion but also promotes Li.sub.2 O in-diffusion into the crystals.

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 crucible adapted for receiving crystal growth starting materials and exposing them to a reactive atmosphere under a carefully controlled temperature environment is disclosed.