Sample records for elektrokhimicheskoe okislenie tantala

  1. Niobia and tantala codoped orthorhombic zirconia ceramics

    International Nuclear Information System (INIS)

    Hoeftberger, M.; Gritzner, G.


    During recent studies it was found that codoping of zirconia with niobia and tantala yielded very corrosion resistant, orthorhombic zirconia ceramics. The powders for those novel ceramics were made via the sol-gel technique by hydrolysis of the respective metal propoxides; a method which required dry-box techniques during the preparation of the alkoxides. In these studies the authors investigated the fabrication of precursor material from aqueous solutions. The preparation of aqueous solutions of salts of zirconium, niobium and tantalum is hampered by rapid hydrolysis. Premature hydrolysis of the chlorides and oxichlorides of niobium, tantalum and zirconium can be, however, prevented in aqueous solutions of oxalic acid. Thus the authors investigated the coprecipitation of hydroxides as precursors by reacting oxalic acid solutions of the respective cations with aqueous ammonia. In addition they studied the effects of calcination and of hydrothermal conversion of the hydroxides to oxides on the powder characteristics and on the mechanical properties of the niobia and tantala codoped zirconia ceramics

  2. Investigations of the mechanical loss of tantala films between 5 and 300 K

    Energy Technology Data Exchange (ETDEWEB)

    Hudl, Matthias; Nawrodt, Ronny; Zimmer, Anja; Nietzsche, Sandor; Vodel, Wolfgang; Seidel, Paul [Friedrich Schiller University (Germany); Tuennermann, Andreas [Institute of Solid-State Physics, Helmholtzweg 5, D-07743 Jena (Germany),; Friedrich Schiller University-Institute of Applied Physics, Jena (Germany)


    Mechanical losses in dielectric mirror coatings of interferometric gravitational wave detectors are a main issue for the proposed advanced generation of gravitational wave detectors. Recent investigations have shown that the mechanical loss of the dielectric mirror coatings (tantala/silica stacks) is probably the main contribution to the detector noise. There are indications that among both coating materials tantala gives the major contribute to mechanical loss. Experimental details of a measuring setup and investigations of the temperature dependency of the mechanical dissipation in thin tantala films on different substrates are presented.

  3. Mechanical loss in tantala/silica dielectric mirror coatings

    International Nuclear Information System (INIS)

    Penn, Steven D; Sneddon, Peter H; Armandula, Helena; Betzwieser, Joseph C; Cagnoli, Gianpietro; Camp, Jordan; Crooks, D R M; Fejer, Martin M; Gretarsson, Andri M; Harry, Gregory M; Hough, Jim; Kittelberger, Scott E; Mortonson, Michael J; Route, Roger; Rowan, Sheila; Vassiliou, Christophoros C


    Current interferometric gravitational wave detectors use test masses with mirror coatings formed from multiple layers of dielectric materials, most commonly alternating layers of SiO 2 (silica) and Ta 2 O 5 (tantala). However, mechanical loss in the Ta 2 O 5 /SiO 2 coatings may limit the design sensitivity for advanced detectors. We have investigated sources of mechanical loss in the Ta 2 O 5 /SiO 2 coatings, including loss associated with the coating-substrate interface, with the coating-layer interfaces and with the coating materials. Our results indicate that the loss is associated with the coating materials and that the loss of Ta 2 O 5 is substantially larger than that of SiO 2

  4. Amorphous tantala and its relationship with the molten state (United States)

    Alderman, O. L. G.; Benmore, C. J.; Neuefeind, J.; Coillet, E.; Mermet, A.; Martinez, V.; Tamalonis, A.; Weber, R.


    The structure factors of molten T a2O5 and N b2O5 have been measured by high-energy x-ray and pulsed neutron diffraction. These are compared to transmission-mode x-ray diffraction through a self-supported 15-μm ion-beam sputtered amorphous tantala film. Atomistic models derived from the diffraction data by means of empirical potential structure refinement reveal that tantala and niobia liquids are very close to isomorphous, as confirmed by measurement of a molten mixture, T a0.8N b1.2O5 . Nonetheless, peak Nb-O bond lengths are about 1 % shorter than those for Ta-O, at temperatures, T*=T /Tmelt , scaled to the melting points. Mean coordination numbers are nM O≃5.6 (1 ) ,nO M≃2.23 (4 ) in the liquid state, and nTaO≃6.6 (2 ) ,nOTa≃2.63 (8 ) in the solid. The liquids are built from five- and six-fold M -O polyhedra which connect principally by corner sharing, with a minority of edge sharing; a-T a2O5 on the other hand has a local structure more akin to the crystalline polymorphs, built primarily from six- and seven-fold polyhedra, with a larger degree of edge sharing. The structural differences between liquid and amorphous T a2O5 , coupled with observations of increasing peak bond lengths upon cooling, are consistent with the interpretation that the amorphous film reaches a supercooled liquidlike metastable equilibrium during deposition. In other words, the amorphous film shares a common progenitor state with a hypothetical glass quenched from a fragile melt. In addition, we show that recent classical interatomic potentials do not fully reproduce the diffraction data, and infer that inclusion of attractive (non-Coulombic) Ta-Ta interactions is important, particularly for obtaining the correct degree of edge sharing, coordination numbers, and densities. Nanoscale inhomogeneity of the amorphous film is confirmed by the observation of small-angle x-ray scattering.

  5. Effect of elevated substrate temperature deposition on the mechanical losses in tantala thin film coatings (United States)

    Vajente, G.; Birney, R.; Ananyeva, A.; Angelova, S.; Asselin, R.; Baloukas, B.; Bassiri, R.; Billingsley, G.; Fejer, M. M.; Gibson, D.; Godbout, L. J.; Gustafson, E.; Heptonstall, A.; Hough, J.; MacFoy, S.; Markosyan, A.; Martin, I. W.; Martinu, L.; Murray, P. G.; Penn, S.; Roorda, S.; Rowan, S.; Schiettekatte, F.; Shink, R.; Torrie, C.; Vine, D.; Reid, S.; Adhikari, R. X.


    Brownian thermal noise in dielectric multilayer coatings limits the sensitivity of current and future interferometric gravitational wave detectors. In this work we explore the possibility of improving the mechanical losses of tantala, often used as the high refractive index material, by depositing it on a substrate held at elevated temperature. Promising results have been previously obtained with this technique when applied to amorphous silicon. We show that depositing tantala on a hot substrate reduced the mechanical losses of the as-deposited coating, but subsequent thermal treatments had a larger impact, as they reduced the losses to levels previously reported in the literature. We also show that the reduction in mechanical loss correlates with increased medium range order in the atomic structure of the coatings using x-ray diffraction and Raman spectroscopy. Finally, a discussion is included on our results, which shows that the elevated temperature deposition of pure tantala coatings does not appear to reduce mechanical loss in a similar way to that reported in the literature for amorphous silicon; and we suggest possible future research directions.

  6. The oxidation; Okislenie

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, V I


    In this chapter of book author determine that alkylene tetra hydro-{gamma}-piron, oxidated by potassium permanganate in all cases of passed oxidation gave oxidation products, confirmatory their structure.

  7. Tantala-based sol-gel coating for capillary microextraction on-line coupled to high-performance liquid chromatography. (United States)

    Tran, MinhPhuong; Turner, Erica B; Segro, Scott S; Fang, Li; Seyyal, Emre; Malik, Abdul


    A sol-gel organic-inorganic hybrid sorbent, consisting of chemically integrated tantalum (V) ethoxide (TaEO) and polypropylene glycol methacrylate (PPGM), was developed for capillary microextraction (CME). The sol-gel sorbent was synthesized within a fused silica capillary through hydrolytic polycondensation of TaEO and chemical incorporation of PPGM into the evolving sol-gel tantala network. A part of the organic-inorganic hybrid sol-gel network evolving in the vicinity of the capillary walls had favorable conditions to get chemically bonded to the silanol groups on the capillary surface forming a surface-bonded coating. The newly developed sol-gel sorbent was employed to isolate and enrich a variety of analytes from aqueous samples for on-line analysis by high-performance liquid chromatography (HPLC) equipped with a UV detector. CME was performed on aqueous samples containing trace concentrations of analytes representing polycyclic aromatic hydrocarbons, ketones, alcohols, amines, nucleosides, and nucleotides. This sol-gel hybrid coating provided efficient extraction with CME-HPLC detection limits ranging from 4.41pM to 28.19 pM. Due to direct chemical bonding between the sol-gel sorbent coating and the fused silica capillary inner surface, this sol-gel sorbent exhibited enhanced solvent stability. The sol-gel tantala-based sorbent also exhibited excellent pH stability over a wide pH range (pH 0-pH 14). Furthermore, it displayed great performance reproducibility in CME-HPLC providing run-to-run HPLC peak area relative standard deviation (RSD) values between 0.23% and 3.83%. The capillary-to-capillary RSD (n=3), characterizing capillary preparation method reproducibility, ranged from 0.24% to 4.11%. The results show great performance consistency and application potential for the sol-gel tantala-PPGM sorbent in various fields including biomedical, pharmaceutical, and environmental areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The effects of heating on mechanical loss in tantala/silica optical coatings

    International Nuclear Information System (INIS)

    Abernathy, Matthew R.; Harry, Gregory M.; Travasso, Flavio; Martin, Iain; Reid, Stuart; Rowan, Sheila; Hough, Jim; Fejer, Martin M.; Route, Roger; Penn, Steve; Armandula, Helena; Gretarsson, Andri


    Second-generation interferometric gravitational-wave detectors will operate at temperatures noticeably above room temperature. Study was done to determine what effect elevated temperatures would have on the Q and coating thermal noise of the detector mirrors. Results show that increased temperature increases loss angle in a manner that is more significant at higher frequencies. Trends show that the increased temperature will have a negligible effect at the low (100 Hz) frequencies important to second-generation detectors

  9. Chapter VII. The oxidation of ethylene line glycerin and of dihydro pyranol. A. General part(theoretical); Glava VII. Okislenie glitserinov etilenovogo ryada i digidropiranolov. A. Obshaya chast'(teoreticheskaya)

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, V I


    In this chapter of book author made conclusion that off-peak compounds obligatory will oxidize above all with breach on place of off-peak connection are incorrect against to off-peak compounds, in which unsaturated carbons connected with oxygen containing carbons.

  10. Structural influences on the laser damage resistance of optical oxide coatings for use at 1064 nm

    Energy Technology Data Exchange (ETDEWEB)

    Hacker, E; Lauth, H; Meyer, J; Weissbrodt, P [Zeiss Jena GmbH, Jena (Germany, F.R.); Wolf, R; Zscherpe, G [Ingenieurhochschule Mittweida (Germany, F.R.); Heyer, H [Sektion Physik, Friedrich-Schiller-Univ. Jena (Germany, F.R.)


    Optical coatings of titania (TiO{sub 2}) and tantala (Ta{sub 2}O{sub 5}) prepared by reactive r.f. diode and d.c. plasmatron sputtering were investigated for the influence of structural properties on the 1064 nm laser damage resistance. Using various methods of characterizing the compositional, crystallographic, microstructural and optical properties, it was found that the damage thresholds are directly related to the content of oxygen in the films in excess of the stoichiometric values, whereas grain sizes and refractive indices show no systematic influences valid for both oxide materials. The highest oxygen-to-metal atomic ratios and thus the highest damage threshold were achieved by the use of r.f diode sputtering. X-ray photospectroscopy investigations of tantala coatings with different oxygen-to-tantalum atomic ratios up to 2.75 revealed for both constituents of the oxide only binding energies representative for tantalum pentoxide. (orig.).

  11. Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

    DEFF Research Database (Denmark)

    Canulescu, Stela; Molchan, Igor S.; Tauziede, C.


    A new method is presented for elemental and molecular analysis of halogen-containing samples by glow discharge time-of-flight mass spectrometry, consisting of detection of negative ions from a pulsed RF glow discharge in argon. Analyte signals are mainly extracted from the afterglow regime...... be used to study the distribution of a tantalum fluoride layer within the anodized tantala layer. Further, comparison is made with data obtained using glow-discharge optical emission spectroscopy, where elemental fluorine can only be detected using a neon plasma. The ionization mechanisms responsible...... for the formation of negative ions in glow discharge time-of-flight mass spectrometry are briefly discussed....

  12. Effects of microstructure on the elastic properties of selected Ta2O5--Eu2O3 compositions

    International Nuclear Information System (INIS)

    Malarkey, C.J.


    Elastic properties and internal friction of selected compositions of tantala-doped monoclinic europia were studied at temperatures up to 1500 0 C using the sonic resonance technique. Unit cell parameters between 25C and 1000 0 C for monoclinic Eu 2 O 3 were calculated from high temperature x-ray diffractometer data. Large-grained monoclinic specimens having less than 6.0 Ta cation percent substitution exhibited anomalous elastic behavior when thermally cycled. Compositions above this addition level exhibited linear elastic behavior. Internal friction values also varied abnormally with grain size, composition, and temperature. The anomalous behavior was attributed to microcracking caused by thermal expansion anisotropies. The critical grain size was found to be approximately 14 μm. The high temperature diffractometry measurements supported the postulate that the grain coarsening effect associated with sintered monoclinic Eu 2 O 3 is the controlling factor for microcracking

  13. Structural and optical properties of sol-gel deposited proton conducting Ta{sub 2}O{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, N.; Lampert, C.M.


    Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC{sub 2}H{sub 5}){sub 5} as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 C, were amorphous. Films heat treated at higher temperatures were crystalline Ta{sub 2}O{sub 5}. The solar transmission values (T{sub s}) of tantala films on glass generally range from 0.8--0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at 550 nm increased from 1.78 to 1.97 with increasing heat treatment from 150 to 450 C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=1x10{sup -3} in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta{sub 2}O{sub 5} films revealed that these films have protonic conductivity of 3.2x10{sup -6} S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.

  14. Medium-Index Mixed-Oxide Layers for Use in AR-Coatings (United States)

    Ganner, Peter


    Ttedesign philosophy of MC-AR-Coatings can be divided into two categories: a) Restriction to two film materials, namely one high-index and one low-index material and b) Use of medium-index layers in addition to high- and low-index layers. Both philosophies have advan-tages and drawbacks. In case a) the total number of layers necessary to obtain a required reflectance curve has to be higher. Thus in case of production errors it can be a problem to find out which layer was responsible for a deviation of the measured reflectance from the nominal one. In case b) using more than two materials reduces the total number of layers and consequently, pinpointing the cause of even small production errors is made simpler. Unfortunately there are not many materials commercially available which can be used to make hard, durable and robust films in the medium-index range namely between n=1.65 and n=2.00. In this paper the results of homogeneous mixtures of Alumina (Al203) and Tantala (Ta205) used for EB-gun evaporated medium-index films in AR-coatings is presented. It is shown that by proper adjustment of the weight percentages of the oxide mixture one can get homogeneous films in this index range. A number of design examples show the favourable application of such layers in AR-coatings. Among the most important ones is the well known QHQ-design for BBAR-coatings as well as AR-designs of the multiple half wave type with extended bandwidth. Further applications of the mixed-oxide layers are AR-coatings for cemented optical elements and beam splitters.

  15. Grafting to Polymethylmethacrylate by the Radiation-Peroxidation Method; Greffage sur le polymethacrylate de methyle par la methode de la radioperoxydation radiochimique; Privivanie k polimetilmetakripatu po metodu radiatsionnogo peroksidirovaniya; Injertos en el polimetilmetacrilato por el metodo de peroxidacion radioinducida

    Energy Technology Data Exchange (ETDEWEB)

    Kircher, J. F.; Markle, R. A.; Lieberman, R.; Sleimers, F. A.; Leininger, R. I. [Batelle Memorial Institute, Columbus, OH (United States)


    e injerta con mayor facilidad que un polimero de peso molecular relativamente elevado. Se observa tambien que al elevar la temperatura hasta alcanzar al punto de transicion de la fase vidriosa aumenta el grado de peroxidacion y de injerto. Los autores proponen una explicacion de los resultados, basada en los efectos de la temperatura y del peso molecular sobre la movilidad del polimero y de los radicales. (author) [Russian] Issledovano radiatsionnoe okislenie polimetilmetakrilata (RMMA) v perekisnoe soedinenie v svyazi s posleduyushchim privivaniem pirrolidonvinila k perekisnomu polimeru. Peroksidirovanie issledovano v zavisimosti ot velichiny dozy, molekulyarnogo vesa RMMA i temperatury izlucheniya. Pokazano, chto RMMA s malym molekulyarnym vesom bolee ehffektivno okislyaetsya do perekisi i privivaetsya pri obluchenii dozami v neskol'ko megarad, chem polimer so sravnitel'no bol'shim molekulyarnym vesom. Otmecheno takzhe, chto povyshenie temperatury primerno do temperatury perekhoda stekla v zhidkoe sostoyanie intensifitsiruet protsessy okisleniya do perekisej i privivaniya. Rezul'taty ob{sup y}asneny, iskhodya iz vliyaniya temperatury i molekulyarnogo vesa na podvizhnost' polimera i oskolochnye radikaly. (author)

  16. The synthesis of the insecticides Aldrin and Dieldrin labelled with carbon-14 at high specific activity; Synthese des insecticides aldrine et dieldrine marques au carbone-14 de haute activite specifique; Sintez insektitsidnogo aldrina i dildrina, mechennykh uglerodom-14 pri vysokoj udel'noj aktivnosti; Sintesis de los insecticidas aldrin y dieldrin de elevada actividad especifica marcados con carbono-14

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Daniel J; Kilner, A Edward [Radiochemical Centre, UKAEA, Amersham, Bucks (United Kingdom)


    nombre comercial que la compania Shell Chemicals dio al 1, 2, 3, 4, 10, 10-hexacloro-1, 4, 4a, 5, 8, 8a-hexabidro-exo-1, 4-endo-5, 8-dimetanonaftaleno. El acetileno-1, 2-{sup 14}C se convierte primero en tetracloroetano y despues en tricloroetileno, y este se condensa con tetracloruro de carbono, por la reaccion de Prins, en presencia de cloruro de aluminio, para dar octaclorociclopenteno. Por decloracion se obtiene hexaclorociclopentadieno que, por una sintesis de Diels-Alder, da biciclo (2, 2, 1) hepta-2, 5-dieno para llegar al aldrin-{sup 14}C con un rendimiento del 12% referido al carbonato de bario. La oxidacion del aldrin da el 6, 7-epoxido, denominado dieldrin, con un rendimiento del 87%. Los autores describen la separacion del octaclorociclopenteno del producto bruto de la reaccion de Prins por cromatografia gas-liquido, y la separacion del aldrin y del dieldrin en pequena escala, por cromatografia sobre el papel, de fase invertida. (author) [Russian] Aldrin - kommercheskoe nazvanie, dannoe SHellom Kemikalom dlya 1 ,2, 3, 4, 10, 10-geksakhloro-1, 4, 4a, 5, 8, 8a-geksagidro ehkso-1,4-ehndo-5,8-dimetanonaftalina. Atsetilen-1,2-C{sup 14} uspeshno prevrashchaetsya v tetrakhloroehtilen i trikhloroehtilen i kondensiruetsya s uglerodistym tetrakhloridom v reaktsii Prinsa v prisutstvii alyuminievogo khlorida v oktakhlorotsiklopentan. Dekhlorizatsiya privodit k geksakhlorotsiklopentadinu, kotoryj dobavlyaetsya v vide Dils-Aldera k bitsiklo (2, 2, 1) gepta-2,5-dinu dlya polucheniya iz barievogo karbonata 12% aldrina-C{sup 14}. Okislenie aldrina privodit k obrazovaniyu ehloksida 6,7 i dildrina v razmere 87%. V dokumente soderzhitsya otchet ob otdelenii oktokhlorotsiklopentana ot syrogo produkta reaktsii Prinsa putem gazozhidkoj khromatografii i ob otdelenii aldrina i dildrina v nebol'shom kolichestve putem obratnoj fazy bumazhnoj khromatografii. (author)

  17. Rare-Earth-Rich Alloys; Alliages a Teneur Elevee en Terres Rares; Splavy, obogashchennye redkozemel'nymi ehlementami; Aleaciones Ricas en Tierras Raras

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, M.; Kato, H. [Albany Metallurgy Research Center, Bureau of Mines, United States Department of the Interior, Albany, OR (United States)


    solubilidad solida del metal aleado con la tierra rara y estudiaron la oxidacion y la corrosion. Los autores no observaron ningun aumento de la resistencia a la oxidacion en la atmosfera que pudiera atribuirse a la aleacion; es mas, la mayor parte de las adiciones ejercieron efectos nocivos. El aluminio mejoro notablemente la resistencia a la corrosion en agua caliente de las tierras raras sometidas a ensayo; la adicion de otros metales no pertenecientes al grupo de las tierras raras tambien aumento esa resistencia, pero en menor grado. (author) [Russian] Redkozemel'nye metally s vysokim secheniem zahvata teplovyh nejtronov predstavljajut interes dlja upravlenija reaktorami, proizvodjashhimi jelektrojenergiju; odnako oni podverzheny korrozii. I s hodja iz toj predposylki, chto neredkozemel'nye metally mogut byt' splavleny s disproziem, orbiem, gadoliniem i samariem i mogut uluchshit' ih svojstva, izucheny vlijanija redkozemel'nyh metallov opredelennyh dobavok ih na splavy. Izuchena rastvorimost' n e redkozemel'nyh metallov cirkonija, vanadija, hroma, zheleza, nikelja, medi, aljuminija i kremnija v disprozii, jerbii, gadolinii i samarii, a takzhe ih vlijanie na tochki plavlenija, preobrazovanie v tverdoe telo i korrozijnye svojstva. Podgotovleny diagrammy faz vplot' do pervyh soedinenij, obogashhennyh redkozemel'nymi jelementami ili jevtetik, kotorye voznikli vpervye. Po zavershenii jetoj chasti raboty byli sozdany splavy, obrabotany pri vysokoj temperature s cel'ju poluchenija maksimal'noj rastvorimosti tverdyh neredkozemel'nyh jelementov, dobavljaemyh dlja splava, i byli provedeny ispytanija na okislenie i korroziju. Pri splavlenii ne nabljudalos' uluchshenija redkozemel'nyh metallov v otnoshenii stojkosti k okisleniju na vozduhe, i fakticheski v bol'shinstve dobavki okazalis' vrednymi. Aljuminij v znachitel'noj stepeni uluchshil soprotivljaemost' k korrozii ot gorjachej vody v aprobirovannyh redkozemel'nyh jelementah; drugie neredkozemel'nye metally pri dobavkah uluchshili

  18. A Contribution to the Study of the Oxidation of Uranium Monocarbide in Carbonic Anhydride at High Temperatures; Contribution a l'etude de l'oxydation du monocarbure d'uranium dans l'anhydride carbonique aux temperatures elevees; Vklad v izuchenie voprosa okisleniya monokarbida urana v ugol'nom angidride pri povyshennykh temperaturakh; Contribucion al estudio de la oxidacion del monocarburo de uranio en anhidrido carbonico a temperaturas elevadas

    Energy Technology Data Exchange (ETDEWEB)

    Desrues, R; Paidassi, J.; Darras, R. [Centre d' Etudes Nucleaires, Saclay (France)


    monocarburo, sea que provengan del uranio o bien del dicarburo, disminuye la resistencia de este compuesto a la oxidacion; ello puede atribuirse sobre todo al hecho de que aquellas sufren una oxidacion muy seria, especialmente a raiz de las tensiones mecanicas que causa. 3. En todos los casos, el proceso de oxidacion puede caracterizarse por una energia de activacion igual a 29 000 cal/M, valor muy proximo al correspondiente a la oxidacion del uranio metalico en el mismo gas y a la difusion del oxigeno en el oxido de uranio (UO{sub 2}) que se forma. (author) [Russian] Obraztsy monokarbida urana, poluchennogo dvumya razlichnymi metodami, i obraztsy ker- meta sostava 96,7 ves% U-3,3 ves% S podvergalis' dejstviyu ugol'nogo angidrida, tshchatel'no ochishchennogo ot kisloroda i vodyanykh parov, v intervalakh 350 - 600 deg. C, i nablyudalos' ikh okislenie odnovremenno mikrograficheskim i gravimetricheskim sposobami pri pomoshchi termovesov Ehjro. Bylo otmecheno sleduyushchee: 1) Krivye vyrazhayut uvelichenie vesa kak funktsiyu vremeni i vnachale nosyat yarko vyrazhennyj linejnyj kharakter, zatem bystro vozrastayut, chto ob{sup y}asnyaetsya, v osnovnom,progressivnym razlozheniem obraztsov. Vprochem, poluchennye dannye uvelicheniya vesa yavlyayutsya bolee nizkimi chem te, kotorye byli opublikovany do nastoyashchego vremeni, chto sleduet, ochevidno, pripisat' bolee vysokoj chistote upotreblennogo ugol'nogo angitrida i ochen' neznachitel'noj poristosti ispol'zovannogo monokarbida urana. 2) Nalichie vklyuchenij v monokarbid, kotorye sootvetstvuyut uranu ili dikarbidu, umen'shaet stojkost' ehtogo materiala k okisleniyu, chto sleduet pripisat', glavnym obrazom,katastroficheskomu okisleniyu samikh vklyuchenij iz-za mekhanicheskikh svyazej. 3) Vo vsekh sluchayakh protsess okisleniya mozhet byt' okharakterizovan ehnergiej aktivatsii, ravnoj 29 000 kal/mol', velichinoj, ochen' blizkoj k toj, kotoraya sootvetstvuet okisleniyu metallicheskogo urana v tom zhe gaze i diffuzii kisloroda v okisi

  19. Lattice Dynamics of Transition Metals; Dynamique de Reseau des Metaux de Transition

    Energy Technology Data Exchange (ETDEWEB)

    Woods, A. D.B. [Chalk River Nuclear Laboratories, Chalk River, ON (Canada)


    {sup 12} c/s para {zeta} = 1.0. Si estas y otras particularidades observadas son anomalias de Kohn, sus posiciones son compatibles con las dimensiones de la superficie de Fermi propuesta por Lomer para los metales de la columna V. Se formula la hipotesis de que las sorprendentes diferencias existentes entre la relacion de dispersion del niobio y la del molibdeno (metales que, segun se cree, poseen estructuras de banda muy semejantes) reflejan diferencias en las energias de Fermi y, por tanto, en las superficies de Fermi de estos materiales. (author) [Russian] Dispersionnoe sootnoshenie chastota/volnovoj vektor v(q) dlja obychnyh vidov kolebanij nekotoryh ob{sup e}mno-centrirovannyh kubicheskih kristallov perehodnyh metallov bylo nedavno izmereno pri komnatnoj temperature. Krivye dispersii dlja niobija, izmerennye Nakagovoj i Vudsom, projavili nekotorye ochen' neobychnye cherty, i rezul'taty mozhno bylo privesti v sootvetstvie tol'ko s pomoshh'ju modeli Born fon Karmana, esli vkljuchit' vzaimodejstvija s ochen' otdalennymi chlenami rjada dal'she vos'mogo. Posledujushhie izmerenija Vudsom tantala dali ochen' pohozhie rezul'taty. Jeto ne udivitel'no, poskol'ku niobij i tantal nahodjatsja v V gruppe periodicheskoj tablicy i mnogie iz ih jelektronnyh svojstv odinakovy. Izmerenija krivyh dispersij molibdena Vudsom i Chenom i vol'frama Chenom i Brok- hauzom pokazali, chto, hotja u jetih metallov, kotorye nahodjatsja v gruppe VI periodicheskoj tablicy, dispersionnye sootnoshenija javljajutsja analogichnymi, jeti dispersionnye sootnoshenija sil'no otlichajutsja ot dispersionnyh sootnoshenij dlja niobija i tantala, nahodjashhihsja v gruppe V. Osnovnye cherty u(q) dlja molibdena i vol'frama ochen' blizko opisyvajutsja tret'im chlenom rjada simmetrichnoj po osjam silovoj modeli Born-fon Karmana, hotja nekotorye vazhnye cherty ne vosproizvodjatsja jetoj model'ju. Odnoj iz takih chert javljaetsja razitel'naja anomalija v prodol'noj [{zeta}{zeta}{zeta}] vetvi (L) dlja molibdena, gde

  20. Isotopic data to study the mechanism of the oxidation of mercaptoacetic acid; Donnees isotopiques pour l'etude du mecanisme d'oxydation de l'acide mercaptoacetique; Izotopnyj metod issledovaniya mekhanizma okisleniya merkapgouksusnoj kisloty; Estudio del mecanismo de oxidacion del acido mercaptoacetico por medio de datos obtenidos con radioisotopos

    Energy Technology Data Exchange (ETDEWEB)

    Gal, D [Central Isotope Laboratory, University of Szeged (Hungary); Guczi, L [Department of Radiology, Elelmiszeripari Kutato Intezet, Budapest (Hungary)


    comparacion de esos resultados con otros datos cineticos, se puede demostrar que la autooxidacion del acido mercaptoacetico en fase liquida constituye una reaccion en cadena ramificada, una de cuyas ramas principales es la formacion de Na{sub 2}S y su oxidacion subsiguiente. Los autores tambien comprobaron que el sulfato que aparece durante la reaccion, procede exclusivamente del sulfuro inorganico. El hierro cataliza la formacion de disulfuro organico y, por lo tanto, ejerce tambien influencia sobre la formacion del sulfuro. (author) [Russian] Mnogie issledovateli izuchali protsessy samookisleniya slozhnykh veshchestv, soderzhashchikh merkaptonovuyu gruppu, s pomoshch'yu molekulyarnogo kisloroda v zhidkoj faze. Ukazyvalos', chto vo vremya reaktsii obrazuetsya sul'fid, no do sikh por ne udavalos' opredelit' tochnogo mekhanizma ehtogo protsessa. Bylo provedeno issledovanie okisleniya merkaptouksusnoj kisloty pri 50{sup o} i pri pH = 8 kak v prisutstvii kompleksona IV, tak i v prisutstvii zheleza. V sistemu byl vveden Na{sub 2}S, mechennyj S{sup 35}, i bylo ustanovleno, chto Na{sub 2}S znachitel'no uvelichivaet skorost' zakhvata kisloroda kak pri protsesse katalizirovannym zhelezom, tak i v protsesse, svobodnom ot ionov zheleza. Vo vremya reaktsii byli izmereny kontsentratsiya sul'fida, ego udel'naya aktivnost' i obshchaya aktivnost'. Na osnovanii ehtikh dannykh i blagodarya vyrabotannomu Nejmanom i ego sotrudnikami kineticheskomu metodu izotopov, predstavilos' vozmozhnym podschitat' temp obrazovaniya sul'fida i ego dal'nejshego okisleniya. Sopostavlenie ehtikh dannykh s drugimi kineticheskimi dannymi pokazalo, chto okislenie merkaptouksusnoj kisloty v zhidkoj faze yavlyaetsya tsepnoj reaktsiej odna iz glavnykh tsepej v ehtoj reaktsii obrazuetsya posredstvom obrazovaniya Na{sub 2}S i ego dal'nejshego okisleniya. Krome togo, bylo ustanovleno, chto vo vremya reaktsii obrazuetsya sul'fat, no tol'ko cherez posredstvo neorganicheskogo sul'fida. Zhelezo katalizirovalo obrazovanie

  1. Preparation of Ceramic-Grade Thorium-Uranium Oxide; Preparation d'un melange d'oxydes de thorium et d'uranium propre a la fabrication de combustible ceramique; Izgotovlenie keramicheskogo torievo-uranovogo okisla; Preparacion de mezclas de oxidos de uranio y torio, de tipo ceramico

    Energy Technology Data Exchange (ETDEWEB)

    Cogliati, G.; De Leone, R.; Ferrari, S.; Gabaglio, M.; Liscia, A. [Centro Studi Nucleari della Casaccia, Rome (Italy)


    izgotovleniya toplivnykh ehlementov, tak i dlya regeneratsii materialov takogo roda. Na pervoj stadii protsessa nitrat uranila vosstanavlivaetsya do nitrata urana (IV). V kachestve vosstanovitelya ispol'zuyutsya kak gazoobraznyj vodorod, tak i murav'inaya kislota; mochevina dobavlyaetsya dlya predotvrashcheniya obrazovaniya azotistoj kisloty, kotoraya uskoryaet povtornoe okislenie urana (IV). V kachestve katalizatora mogut primenyat'sya platina i palladij. Privodyatsya dannye dlya nepreryvnogo protsessa, v kotorom murav'inaya kislota i mochevina dobavlyayutsya k rastvoru, poslednij zatem podogrevaetsya i podaetsya v kolonku, zapolnennuyu alyuminievymi tabletkami razmerom 3,87 x 3,17 mm, 0,5% kotorykh sostavlyaet platina. Izucheny vliyaniya skorosti potoka, temperatury, kontsentratsii murav'inoj kisloty i mocheviny, a takzhe prodolzhitel'nost' sluzhby i otravlenie katalizatora. Vtoraya stadiya protsessa zaklyuchaetsya v osazhdenii oksalato'v toriya i urana (IV). Opisyvaetsya vliyanie shchavelevoj kisloty na otnoshenie torij/uran, temperatury i vremeni stareniya na otstaivanie i fil'tratsionnye kharakteristiki osadka i na keramicheskie svojstva poluchennykh poroshkov. Prokalka proizvodilas' kak v vosstanovitel'noj, tak i v okislitel'noj atmosferakh. Posle predvaritel'nykh ispytanij byli prinyaty dva standartnykh metoda izgotovleniya keramicheskikh izdelij, a imenno: kholodnaya pressovka i spekanie, ehkstruziya i spekanie. Spekaemost' razlichnykh poroshkov byla ispytana s pomoshch'yu ehtikh oboikh standartnykh metodov. S nekotorymi poroshkami byli polucheny plotnosti svyshe 95% teoreticheski dopustimoj. Uspeshno byli provedeny ispytaniya na vosproizvodimost'. (author)

  2. Recoil Processes of Cr{sup 51} in Mixed Inorganic Systems; Processus de Recul de {sup 51}Cr dans des Melanges Inorganique; 041f 0420 041e 0426 0415 0421 0421 042b 0421 042f 0414 0420 0410 041c 0418 041e 0422 0414 0410 0427 0418 0425 0420 041e 041c 0410 -51 0412 0421 041c 0415 III 0410 041d 041d 042b 0425 041d 0415 041e 0420 0413 0410 041d 0418 0427 0415 0421 041a 0418 0425 0421 0418 0421 0422 0415 041c 0410 0425 ; Procesos de Retroceso del {sup 51}Cr en Sistemas Inorganicos Mixtos

    Energy Technology Data Exchange (ETDEWEB)

    Veljkovic, S. R.; Milenkovic, S. M.; Ratkovic, M. R. [Boris Kidric Institute of Nuclear Sciences, Vinca, Yugoslavia (Serbia); Faculty Of Natural Sciences, Belgrade University, Belgrade, Yugoslavia (Serbia)


    smesjah hromatov ili solej hroma s neorganicheskimi okislami. V kachestve okislov ispol'zovalis' AI{sub 2}O{sub 3}, SiO{sub 2} i MgO. Termicheskie jeffekty kontrolirovalis' parallel'no dlja ocenki chisto teplovyh vozdejstvij v reaktore i dlja ocenki vozmozhnogo vnutrennego nagreva v mishenjah. V sisteme, gde hromaty byli osazhdeny na MgO, nabljudalos' sil'noe vosstanovlenie do hrom-iona. Pri temperature obluchenija nejtronnye jeffekty prevalirovali nad termicheskimi processami i tol'ko nagrevanie do temperatury vyshe 600 Degree-Sign S davalo podobnyj rezul'tat. Ion hroma vo vremja obluchenija ne izmenilsja. Uvelichenie koncentracii hromatov privodilo k horosho izvestnomu uderzhaniju Cr{sup 51}O{sub 4}{sup =}. Hromaty, adsorbirovannye na glinozeme, sohranjali formu okisi tak zhe, kak i v sisteme s SiO{sub 2}. Teplovye jeffekty imeli to zhe samoe napravlenie. Ion hroma, absorbirovannyj na jetih okisjah, vedet sebja razlichno. V sisteme s glinozemom otmechalos' sil'noe okislenie, kotoroe znachitel'no prevyshalo vklad teplovyh processov. Pri sravnenii jeffekta obluchenija i nagreva v sisteme s SiO{sub 2} obnaruzhena nebol'shaja raznica, hotja bylo otmecheno bol'shoe diffuzionnoe obednenie poverhnosti ionami hroma. Obshhaja osobennost' vseh sistem sostoit v ochen' nebol'shoj koncentracii soedinenij hroma. Himija tonkogo sloja, po-vidimomu, otlichaetsja ot obychnogo povedenija bol'shih mass hromatov v bol'shinstve sluchaev, kak v teplovyh processah, tak i v processe otdachi. Jeto mozhet oznachat', chto processy v ''gorjachih tochkah'', nahodjas' v zavisimosti ot vseh komponentov, mogut davat' himicheskie produkty, chuvstvitel'nye k harakteru misheni. Obobshhennaja kartina processov s jadrami otdachi v tverdyh soedinenijah, po-vidimomu, nuzhdaetsja v dopolnitel'nom rassmotrenii voprosa o materiale matric. (author)

  3. Liquid Scintillation Detection of Tritium and other Radioisotopes in Insoluble or Quenching Organic Samples; Detection par compteur a scintillations a liquides du tritium et des autres radioelements contenus dans des echantillons organiques insolubles ou coupeurs; Obnaruzhenie tritiya metodom zhidkostnoj stsintillyatsii v nerastvorimykh ili sposo'nykh gasit' izluchenie organicheskikh o'raztsakh; Deteccion del tritio u otros radioisotopos por centelleo liquido en muestras organicas insolubles o que provocan extincion

    Energy Technology Data Exchange (ETDEWEB)

    Eastham, J F; Westbrook, H L; Gonzales, D [University of Tennessee, Knoxville, TN (United States)


    stsintillyatsionnoe gashenie mnogimi organicheskimi obraztsami i ogranichennaya rastvorimost ' drugikh, prisushchi takzhe biologicheskim veshchestvam. Razrabotannye protsedury vklyuchayut v sebya okislenie obernutogo v fil'troval'nuyu bumagu obraztsa v kolbe, napolnennoj kislorodom, obrazovanie rastvora okislennykh produktov v sootvetstvuyushchem rastvoritele, dobavlennom v kolbu pered okisleniem, i stsintillyatsionnyj schet rastvora. Preimushchestva razrabotannykh protsedur dlya preodoleniya ukazannykh ogranichenij vklyuchayut: kachestvo operatsii s obraztsami bol'shogo diapazona aktivnosti (nekotorye s takoj nizkoj aktivnost'yu kak 1{mu}c//mo1e), bol'shuyu tochnost' (takuyu zhe kak pri lyubom drugom obshchem metode izmereniya radioaktivnosti H{sup 3}), i primenimost' k drugim myagkim beta-izluchatelyam (C{sup 14} i k{sup 35}). S pomoshch'yu stsintillyatsionnogo spektrometra i razrabotannykh protsedur mozhet byt' razdel'no izmerena radioaktivnost ' obraztsov mechennykh trizhdy H{sup 3}, C{sup 14} i k{sup 35}. Detali, kasayushchiesya sistem rastvoritelya i razrabotannykh metodov, budut izlozheny v doklade, krome togo v nem budet dana rabochaya kharakteristika novogo, otnositel'no nedorogogo odnokanal'nogo stsintillyatsionnogo spektrometra. Budut izlozheny analiticheskie rezul'taty, kasayushchiesya takogo gasyashchego izluchenie materiala, kak 2,4-dinitro-fenilgidrozony i tiazolidy, a takzhe takikh nerastvorimykh materialov, kak proteiny i ugolevdy. Budet obsuzhdeno primenenie metodov k otsenke izotopnogo ehffekta H{sup 1}/H{sup 3} v opredelennykh reaktsiyakh vosstanovleniya. (author)

  4. Present Status of Nitrogen Fixation by Reactor Radiation; Etat Actuel des Recherches sur l'oxydation directe de l'azote sous irradiation dans des reacteurs; Sovremennoe sostoyani opytov po okisleniyu azota izlucheniem iz reaktorov; Estado actual de las investigaciones sobre fijacion del nitrogeno por irradiacion en reactores

    Energy Technology Data Exchange (ETDEWEB)

    Harteck, P; Dondes, S [Rensselaer Polytechnic Institute, Troy, NY (United States)


    fision liberada en las fibras de vidrio y de la resistencia termica del circuito. Otro circuito, que habra de funcionar a 50 - 75 atmosferas y 600{sup o}C se encuentra en curso de construccion. Estos circuitos permitiran evaluar las caracteristicas de un sistema continuo, incluido el comportamient o de los productos de fision liberados en la corriente gaseosa. Los autores distinguen tres fases en la cinetica compleja de la oxidacion del nitrogeno: reacciones iniciales en el sistema;, reacciones subsiguientes a la fijacion de cierta cantidad de nitrogeno y, por ultimo, cinetica del equilibrio alcanzado en presencia de radiaciones. Se estudian las condiciones necesarias para la formacion de N{sub 2}0{sub 5}, N{sub 2}0{sub 4} y O{sub 3}, asi como los efectos que ejercen sobre el proceso en conjunto. (author) [Russian] Pri issledovaniyakh okisleniya azota izlucheniem iz reaktorov, kotorye proizvodilis ' v Rensselerovskom institute i v Brukkhejvenskoj natsional'noj laboratorii v techenie ryada let, byla ispol'zovana, v kachestve neposredstvennogo ioniziruyushchego izlucheniya, ehnergiya otdachi oskolkov deleniya putem rasseyaniya urana-235 v steklyannom volokne diametrom priblizitel'no v 5 mikronov. Bylo opredeleno vliyanie temperatury, davleniya i sootnosheniya mezhdu kolichestvom azota i kolichestvom kisloroda na velichinu radiatsionno-khimicheskogo vykhoda G na okislenie azota i rezul'taty byli soobshcheny v tekhnicheskoj literature. Nizhe daetsya kratkaya svodka ehtoj raboty. Upomyanutaya vyshe rabota proizvodilas' nad staticheskimi sistemami ; nedavno proizvedennaya rabota okhvatyvala kak staticheskie, tak i tsiklicheskie sistemy. V staticheskikh sistemakh glavnoe vnimanie obrashchalos' na vliyanie intensivnosti izlucheniya, v osobennosti v sostoyanii kineticheskogo ravnovesiya izlucheniya. Bylo ustanovleno, chto obrazovanie N0{sub 2}. i N{sub 2}0 V smesyakh azota i kisloroda v proportsiyakh 4:1 i 2: 1 proiskhodit do polnogo istoshcheniya yusloroda. TSiklicheskaya

  5. Chemical Behaviour of C{sup 11} in Liquid Hydrocarbons; Comportement Chimique de {sup 11}C dans les Hydrocarbures Liquides; Khimicheskaya kharakteristika ugleroda-11 v zhidkikh uglevodorodakh; Comportamiento Quimico del {sup 11}C en Hidrocarburos Liquidos

    Energy Technology Data Exchange (ETDEWEB)

    Voigt, A. F.; Clark, D. E.; Mesich, F. G. [Institute of Atomic Research and Department of Chemistry, Iowa State University, Ames, IA (United States)


    moleculas blanco en distintas condiciones de dosificacion. Los experimentos en curso sobre moleculas analogas en tamano a las del blanco han contribuido a la aclaracion de los mecanismos de recombinacion de los atomos de retroceso. Particular interes reviste el rendimiento de productos con un atomo de carbono mas que el blanco, que resultan de una reaccion de adicion. La localizacion del atomo adicional en una molecula blanco que tenga varios lugares de adicion proporciona informacion sobre la naturaleza del proceso. Cuando el atomo de retroceso es moderado y su energia disminuye hasta el punto en que es posible la formacion de un enlace, al menos temporal, el exceso de energia que el atomo llC cede al sistema puede originar la ruptura de otros enlaces del complejo activado, lo que suele dar origen a un producto de dos atomos de carbono. Si el complejo es capaz de conservar su integridad, suele resultar un producto de adicion. Por tanto, la comparacion del rendimiento de compuestos de dos atomos de carbono (acetileno, etileno y etano) y de productos de adicion proporciona una informacion valiosa sobre la energia a la que pueden formarse enlaces estables, y sobre la naturaleza del grupo que contiene el {sup 11}C y que participa en la reaccion. (author) [Russian] Uglerod-11 obrazuetsja v rezul'tate reakcii C{sup 12}({gamma}, n)C{sup 11} v puchke tormoznogo izluchenija v sinhrotrone s jenergiej jelektronov 70 Mjev. V kachestve veshhestva misheni primenjalis' zhidkie uglevodorody s pjat'ju i shest'ju atomami ugleroda, v tom chisle normal'nye razvetvlennye i aliciklicheskie pentany i geksany, a takzhe benzol. Povedenie C{sub 11} izuchalos' metodom gazohromatograficheskogo razdelenija produktov, scheta aktivnosti C{sub 11} v gazovom potoke v kamere, pomeshhennoj v scintilljacionnyj schetchik kanal'nogo tipa. V kazhdom jeksperimente vyhody razlichnyh produktov sravnivalis' s vyhodom acetilena kak vnutrennego standarta, a takzhe libo s pokazanijami registratora tantala, libo s