Sample records for oxybromides
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Chemical treatment makes aromatic polyamide fabric fireproof in oxygen atmosphere
NASA Technical Reports Server (NTRS)
Cardwell, R. O.; Holsten, J. R.; Rives, J. W.
1970-01-01
Organic fabric is reacted first with vapors of a phosphorus oxychloride, phosphorus oxybromide solution and then with bromine vapor, after neutralization it is flameproof in pure oxygen atmosphere. Soaking the fabric with mixture of ammonium polyphosphates increases flame resistance, but the polyphosphates are leached out during laundering.
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Synthesis of Green-Emitting (La,Gd)OBr:Tb3+ Phosphors
Kim, Sun Woog; Jyoko, Kazuya; Masui, Toshiyuki; Imanaka, Nobuhito
2010-01-01
Green-emitting phosphors based on lanthanum-gadolinium oxybromide were synthesized in a single phase form by the conventional solid state reaction method, and photoluminescence properties of them were characterized. The excitation peak wavelength of (La1-xGdx)OBr:Tb3+ shifted to the shorter wavelength side with the increase in the crystal field around the Tb3+ ions by doping Gd3+ ions into the La3+ site, and, as a result, the green emission intensity was successfully enhanced. The maximum emission intensity was obtained for (La0.95Gd0.05)OBr:5%Tb3+, where the relative emission intensity was 45% of that of a commercial green-emitting LaPO4:Ce3+,Tb3+ phosphor.
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Rare earth phosphors and phosphor screens
Buchanan, Robert A.; Maple, T. Grant; Sklensky, Alden F.
1981-01-01
This invention relates to rare earth phosphor screens for converting image carrying incident radiation to image carrying visible or near-visible radiation and to the rare earth phosphor materials utilized in such screens. The invention further relates to methods for converting image carrying charged particles to image carrying radiation principally in the blue and near-ultraviolet region of the spectrum and to stabilized rare earth phosphors characterized by having a continuous surface layer of the phosphors of the invention. More particularly, the phosphors of the invention are oxychlorides and oxybromides of yttrium, lanthanum and gadolinium activated with trivalent cerium and the conversion screens are of the type illustratively including x-ray conversion screens, image amplifier tube screens, neutron imaging screens, cathode ray tube screens, high energy gamma ray screens, scintillation detector screens and screens for real-time translation of image carrying high energy radiation to image carrying visible or near-visible radiation.
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NASA Astrophysics Data System (ADS)
Kanagaraj, Thamaraiselvi; Thiripuranthagan, Sivakumar; Paskalis, Sahaya Murphin Kumar; Abe, Hideki
2017-12-01
Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x = 5, 10, 30, 50 & 70 wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.
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Gas Phase Chromatography of some Group 4, 5, and 6 Halides
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sylwester, Eric Robert
1998-10-01
Gas phase chromatography using The Heavy Element Volatility Instrument (HEVI) and the On Line Gas Apparatus (OLGA III) was used to determine volatilities of ZrBr 4, HfBr 4, RfBr 4, NbBr 5, TaOBr 3, HaCl 5, WBr 6, FrBr, and BiBr 3. Short-lived isotopes of Zr, Hf, Rf, Nb, Ta, Ha, W, and Bi were produced via compound nucleus reactions at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and transported to the experimental apparatus using a He gas transport system. The isotopes were halogenated, separated from the other reaction products, and their volatilities determined by isothermal gas phase chromatography.more » Adsorption Enthalpy (ΔH a) values for these compounds were calculated using a Monte Carlo simulation program modeling the gas phase chromatography column. All bromides showed lower volatility than molecules of similar molecular structures formed as chlorides, but followed similar trends by central element. Tantalum was observed to form the oxybromide, analogous to the formation of the oxychloride under the same conditions. For the group 4 elements, the following order in volatility and ΔH a was observed: RfBr 4 > ZrBr 4 > HfBr 4. The ΔH a values determined for the group 4, 5, and 6 halides are in general agreement with other experimental data and theoretical predictions. Preliminary experiments were performed on Me-bromides. A new measurement of the half-life of 261Rf was performed. 261Rf was produced via the 248Cm( 18O, 5n) reaction and observed with a half-life of 74 -6 +7 seconds, in excellent agreement with the previous measurement of 78 -6 +11 seconds. We recommend a new half-life of 75±7 seconds for 261Rf based on these two measurements. Preliminary studies in transforming HEVI from an isothermal (constant temperature) gas phase chromatography instrument to a thermochromatographic (variable temperature) instrument have been completed. Thermochromatography is a technique that can be used to study the volatility and ΔH a of longer-lived isotopes off-line, Future work will include a comparison between the two techniques and the use of thermochromatography to study isotopes in a wider range of half-lives and molecular structures.« less
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Bismuth Oxybromide-based Photocatalysts: Syntheses, Characterizations and Applications
NASA Astrophysics Data System (ADS)
Wu, Dan
The increasing intractable crises of environmental pollution and fossil fuels shortage are among the biggest challenges in current society and becoming an overwhelming concern for the development of our future world. Semiconductor photocatalysis has received considerable interdisciplinary attention and research interest owing to their diverse potentials in energy and environmental applications. As an important V-VI-VII ternary semiconductor, BiOBr has been recently received considerable attention owing to its fascinating physicochemical prosperities originated from its unique layered structures. However, existing reports on the photocatalytic bacterial inactivation of BiOBr based photocatalysts are rather limited. In addition, the mechanisms in visible-light-driven (VLD) photocatalytic disinfection systems are far from fully understandable. Moreover, the exploitation of facile ways to make BiOBr photocatalysts harvesting a wide range of solar spectrum with high efficiency remains challenging, yet highly desirable. In this study, BiOBr based photocatalysts with various nanostructures were synthesized and characterized. Their photocatalytic activities were systematically investigated towards bacterial inactivation, dye degradation and CO2 reduction. The exploration on the photo-excited charge carriers and reactive species were conducted to gain some insight into the corresponding photocatalytic mechanisms. Firstly, BiOBr 2D nanosheets with a high percentage of exposed {001} and {010} facets were synthesized via a facile hydrothermal method. BiOBr with dominant {001} facet (B001) nanosheets exhibited remarkably higher photocatalytic activity in inactivating E. coli K-12 under visible light irradiation, in comparison with BiOBr with dominant {010} facet (B010) nanosheets. There were 7-log bacterial cells inactivated within 2 h for B001, while B010 needed 6 h irradiation to inactivate 6.5-log bacterial cells. This superior activity was assigned to the more favorable separation and transfer of photogenerated e-/h+ pairs as well as more oxygen vacancies in B001 nanosheets, resulting in faster production and further accumulation of •O2- and h+ within a short time. Secondly, B was doped into BiOBr nanosheets without changing the morphology, crystal structure, and {001}-facet exposed features compared with pure BiOBr nanosheets. The photocatalytic activities were investigated by inactivating E. coli K-12 bacteria using fluorescence tubes as visible light sources. Significantly, 0.75B-BiOBr (0.75% molar ratio of B/Bi) showed the best photocatalytic efficiency with 7-log bacterial cells inactivation within 30 min, compared with 2-log for pure BiOBr. Photogenerated h+ was the major reactive species accounting for the B-BiOBr inactivation system. With its electron-deficient characteristics, the B dopant is favorable to accept extra e- from VB of BiOBr, leading to improved e- /h+ separation efficiency. In addition, the destruction process of bacterial cell was also observed from the destruction of cell membrane to the intracellular components. Finally, a simple alkali (NaOH) post-treatment approach was applied to obtain BiOBr-0.01 with brown color. Bi2O4 nanoparticles were in situ formed due to a combined action of NaOH-induced dehalogenation and light triggered photoexcited h+ oxidation processes on the surface of BiOBr nanosheets. Significantly, without any foreign elements, the light absorption of BiOBr-0.01 was extended to the near infrared (NIR) region. Compared with normal BiOBr, BiOBr-0.01 nanosheet showed superior photocatalytic activity for the dye degradation and microbial disinfection. Particularly, it exhibits excellent capability to photocatalytically reduce CO2 into CO and CH4, whereas the normal BiOBr is completely incapable for CO2 conversion under simulated sunlight irradiation. The exceptional enhancement is due to the Bi2O4 extended light absorption, efficient e-/h + separation, and the increased surface-adsorbed ability to reactants. This facile post-treatment method is promising for different bismuth-based systems and hence offers a path to a large variety of materials.