E.i. Dupont De Nemours and Company

August Ferretti

John D Bierlein

Lothar H Brixner

Mark Gerrit Roelofs

Thurman E Gier

William Yang-Hsing Hsu

Patricia A Morris

Oral R Van Buskirk

Albert A Ballman

Wu-Hsun Cheng

A seal apparatus is disclosed for sealing an outlet of a pressurized chamber from fluid loss from the chamber and contamination to the chamber. The apparatus includes certain combinations of (a) a chamber outlet structure; (b) a removable cover; (c) means for reversibly connecting the cover to the chamber outlet structure; and (d) a compressible self-energizing ring having a surface which consists essentially of a material selected from the group consisting of noble metals, noble metal alloys and polytetrafluoroethylene, which has a hardness selected to substantially avoid deformation when the cover is sealed to the chamber outlet structure. Also disclosed are certain pressure vessels for hydrothermal crystal growth using a crystal growth media, which comprise (a) a vessel base and (b) a removable vessel cover. The vessels include (i) certain said combinations employing a compressible self-energizing ring with a surface resistant to corrosion by the crystal growth media and a hardness lower than the hardness of the seal surfaces of the base and cover; and/or (ii) (in an aspect of this invention especially suited for the growth of crystals of the formula MTiOXO.sub.4 wherein M is selected from the group consisting of K, Rb, Tl, NH.sub.4 and mixtures thereof and X is selected from the group consisting of P, As and mixtures thereof) vessel bodies of a nickel alloy essentially free of titanium.

Hydrothermal crystallization vessels

A europium-doped barium fluorohalide photostimulable phosphor comprises an amount of oxygen sufficient to create a concentration of anion vacancies effective to substantially increase the stored photostimulable energy, compared to a non-oxygen-treated phosphor.

Photostimulable europium-doped barium fluorobromide phosphors

A process for producing BaFBr:Eu phosphors in which a slurry of an Eu halide, BaFBr and BaBr.sub.2 is spray dried to produce spherical agglomerates which are then fired and cooled by an inert atmosphere, washed to remove unreacted BaBr.sub.2 and dried to produce a powder.

BafBr:Eu phosphors

Process for preparing BaFBr:Eu phosphors

There is disclosed an optical waveguide comprising a K.sub.1-x Rb.sub.x TiOmO.sub.4 single crystal substrate, wherein x is from 0 to 1 and M is P or As, having at least one optically smooth surface wherein sufficient K.sup.+ and/or Rb.sup.+ have been replaced by ions selected from at least one of H.sup.+ and NH.sub.4.sup.+ and, optionally, at least one monovalent ion selected from Rb.sup.+, Cs.sup.+, Tl.sup.+, and/or at least one divalent ion selected from Ba.sup.+2, Sr.sup.+2, Ca.sup.+2 and Pb.sup.+2 to chance the surface index of refraction at least a 0.00025 with respect to the index of refraction of the single crystal substrate. One process disclosed for producing an optical waveguide comprises the steps of contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOmO.sub.4 with an ion exchange medium capable of supplying said replacement ions, at a temperature of from about 100.degree. C. to about 600.degree. C. for a time sufficient to increase the surface index of refraction at least about 0.00025 with respect to the index of refraction of the single crystal by replacing K.sup.+ and/or Rb.sup.+ of said single crystal with said ions supplied by the exchange medium, and cooling the resulting crystal. Another process disclosed for producing an optical waveguide comprises the step of applying a DC voltage of from about 20 V per cm of crystal thickness to about 2000 V per cm of crystal thickness across the z-surfaces of a z-cut K.sub.1-x Rb.sub.x TiOmO.sub.4 single crystal, in the presence of a proton source at a temperature of from about -40.degree. C. to 400.degree. C. for a time sufficient to raise the index of refraction underneath the anode by at least 0.00025 with respect to the index of refraction of the single crystal by replacing K.sup.+ and/or Rb.sup.+ of said single crystal with H.sup.+. A nonlinear optic device using the optical waveguide of the invention is also disclosed.

Processes for preparation of ion exchanged crystalline waveguides

There is disclosed an optical waveguide comprising a K.sub.1-x Rb.sub.x TiOMO.sub.4 single crystal substrate, wherein x is from 0 to 1 and M is P or As, having at least one optically smooth surface wherein sufficient K.sup.+ and/or Rb.sup.+ have been replaced by ions selected from at least one of H.sup.+ and NH.sub.4.sup.+ and, optionally, at least one monovalent ion selected from Rb.sup.+, Cs.sup.+, Tl.sup.+, and/or at least one divalent ion selected from Ba.sup.+2, Sr.sup.+2, Ca.sup.+2 and Pb.sup.+2 change the surface index of refraction at least about 0.00025 with respect to the index of refraction of the single crystal substrate. One process disclosed for producing an optical waveguide comprises the steps of contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOMO.sub.4 with an ion exchange medium capable of supplying said replacement ions for sufficient time at a temperature of from about 100.degree. C. to about 600.degree. C., and cooling the resulting crystal. Another process disclosed for producing an optical waveguide comprises the step of applying a DC voltage of from about 20 V per cm of crystal thickness to about 2000 V per cam of crystal thickness across the z-surfaces of a z-cut K.sub.1-x Rb.sub.x TiOMO.sub.4 single crystal, in the presence of a proton source for sufficient time at a temperature of from about -40.degree. C. to 400.degree. C. A nonlinear optic device using the optical waveguide of the invention is also disclosed.

Ion exchanged crystalline waveguides and processes for their preparation

The activity of nonfused methanol dissociation catalysts containing copper and optionally chromium, magnesium, calcium, barium, strontium, manganese, molybdenum, ruthenium and palladium can be improved by the incorporation of 0.1 to 20 weight percent amorphous silica.

Methanol dissociation catalysts

A composition is disclosed which consists essentially of doped crystalline MTiOXO.sub.4 (wherein M is selected from the group consisting of K, Rb and Tl, X is selected from the group consisting of P and As) which contain at least about 100 ppm total of at least one dopant selected from the group consisting of Ga, Al and Si. The compositions generally have low ionic conductivity, and may be prepared using an improved flux process wherein Ga, Al and/or Si dopant is added to the flux in a total amount of at least about 0.5 mole % and the crystallization temperature is controlled to provide a crystalline composition containing the desired amount of dopant.

Doped crystalline compositions and a method for preparation thereof

A hydrothermal process for growing a crystal of MTiOXO.sub.4 at an elevated temperature is disclosed which employs a growth medium comprising a mineralizer solution, and is characterized as employing aqeuous mineralizer solution in which the concentration of M is at least about 8 molar, and as employing a growth region temperature of less than about 500.degree. C. and/or a pressure of less than 14,000 psi during crystallization. M is selected from the group consisting of K, Rb, Tl and NH.sub.4 and mixtures thereof, and X is selected from the group consisting of P and As and mixtures thereof.

Hydrothermal process for growing optical-quality single crystals

There is disclosed a process for producing an optical waveguide comprising contacting at least one optically smooth surface of a single crystal of K.sub.1-x Rb.sub.x TiOMO.sub.4 wherein x is from 0 to 1 and M is P or As with a specified molten salt of at least one of Rb, Cs and Tl at a temperature of from about 200.degree. C. to about 600.degree. C. for a time sufficient to increase the surface index of refraction at least about 0.00025 with respect to the index of refraction of the starting crystal, and cooling the resulting crystal. The product made thereby and a waveguide device using the same are also disclosed.

Process for producing an optical waveguide

Process for producing an optical waveguide and the product therefrom

Process for preparing spheroidal particulate BaFCl:Eu phosphor having a narrow size distribution, which process comprises:

Process for spheroidal BaFCl:Eu phosphor particles

Method for making a pyrochlore of the formula Bi.sub.2-x M.sub.x B.sub.2 O.sub.7-z by firing finely divided particles of bismuth oxycarbonate. The pyrochlores made by the invention have a high surface area and are especially useful as the conductive phase for thick film resistors.

Method for making high surface area bismuth-containing pyrochlores

A process for preparing BaFCl:Eu phosphors of controllable particle size and size distribution is provided. The process comprises (a) preparing an intimate mixture of fine particles of BaFCl, a europium source, preferably water-soluble EuCl.sub.3, and a water-soluble chloride as flux; (b) firing the mixture in an inert atmosphere at a temperature in the range of about 550.degree.-900.degree. C and above the liquid temperature of the flux for a time sufficient to effect reaction and diffusion, and (c) washing the fired product with water to remove the chloride flux. By preselecting the combination of firing temperature and flux concentration in the mixture, phosphor particles of a predetermined size and size distribution can be obtained. This control of the phosphor product is especially advantageous when the intimate mixture is formed in an aqueous medium.

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Wilmington, DE, United States of America

August Ferretti