摘要:
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.
摘要:
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.
摘要翻译:在含有与氢氧根离子(OH-)反应并除去氢氧根离子(OH-))的反应性组分的气氛中,超导氧化物材料被超氧化。 优选的反应性组分包括H 2 O 2,N 2 O和I 2。 反应性组分与前体材料反应并除去氢氧根离子,在超导氧化物材料中比在分子氧中氧化可能达到更高的氧化态。 使用这种反应性组分允许在常规温度下快速氧化前体材料,并且使用较低温度来实现氧化。
摘要:
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.
摘要:
A ceramic sensor (12) comprising a thin film (14) of Cu.sub.1=x Mn.sub.2-x O.sub.4-y is provided that quantitatively measures the partial pressure of CO gas in a flowing system (22). The sensor is specific to CO gas and is negligibly affected by the presence of the common automobile exhaust vapors NO, H.sub.2 O, and CH.sub.4, within the operational temperature range from about 250.degree. to 450.degree. C. The CO sensor of the invention has other applications, such as monitoring CO levels in laboratories, mines, and industrial smoke stacks, and may be used in environments up to about 700.degree. C.
摘要:
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.
摘要:
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. Then the oxide-containing precipitate is subjected to a reactive atmosphere process by exposing the powder to a chosen gas phase reactive atmosphere comprising atomic halogen at a predetermined elevated temperature for a predetermined period of time, to remove traces of water and water-derived impurities from the oxide.
摘要:
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.
摘要:
A high concentration of diatomic molecules is caged in a host crystal by a crystal growth process, in which all other internal degrees of freedom of the diatomic molecule, except the vibrational, are frozen. Such a system provides an efficient mid-infrared, solid-state laser that can be pumped by a laser diode. Other uses include magnetic (Faraday) rotators, electro-optic switches, and Q-switches. The crystal growth process employs Czochralski-type or Bridgman-type processes under high pressure to introduce the diatomic molecule into the host lattice at a temperature slightly above the melting point of the host crystal, followed by slow cooling.
摘要:
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.
摘要:
A process of fabricating a hybrid single crystal fiber having nonlinear optical properties such as frequency doubling. Said process includes applying a force to a fiber core resting upon a bulk nonlinear crystal such as LiIO.sub.3 in a saturated solution of LiIO.sub.3 in water. After the core is embedded a sufficient distance into the crystal the force is removed.