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Sample records for include alumina yttrium

  1. Preparing magnetic yttrium iron garnet nanodot arrays by ultrathin anodic alumina template on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Hui; Han, Mangui, E-mail: han-mangui@yahoo.com; Deng, Longjiang [National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zheng, Liang; Zheng, Peng; Qin, Huibin [Institute of Electron Device and Application, Hangzhou Dianzi University, Hangzhou 310008 (China); Wu, Qiong [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

    2015-08-10

    Ultrahigh density periodically ordered magnetic yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) nanodot arrays have been prepared by pulsed laser deposition through an ultrathin alumina mask (UTAM). UTAM having periodically ordered circularly shaped holes with 350 nm in diameter, 450 nm in inter-pore distance, and 700 nm in height has been prepared on silicon substrate. Furthermore, the microstructure and magnetic properties of YIG nanodot arrays have been characterized. Nanodot arrays with a sharp distribution in diameter centered at 340 nm with standard deviation of 10 nm have been fabricated. Moreover, typical hysteresis loops and ferromagnetic resonance spectra in in-plane and out-of-plane revealed that this unique structure greatly influences the magnetics properties of YIG. First, coercivity of YIG nanodot arrays in in-plane was increased about from 15 Oe of YIG films to 500 Oe. Then, the degree of uniformity about nanodot height decided that two or more resonance peaks in out-of-plane were detected in the spectra. The peak-to-peak linewidth values were about 94 Oe and 40 Oe in the parallel and perpendicular directions, respectively, which indicated that the values were larger by the two-magnon scattering. Consequently, this pattering method creates opportunities for studying physics in oxide nanomagnets and may be applied in spin-wave devices.

  2. Interpretation of alumina/yttrium-aluminium garnet orientation relationships by geometric criteria

    International Nuclear Information System (INIS)

    Hay, R.S.; Matson, L.E.

    1991-01-01

    This paper reports on geometric criteria for low interface energy and interface structure were tested for the cubic-rhombohedral system YAG/alumina. Orientation relationships near (111)[110] a parallel (112)[110] y and facets on (111) a (112) y were observed in both sol-gel derived composites and directionally solidified eutectic composites. The Σ YAG = 12 near-CSL of 2[111], [110], [112] was inferred to be the preferred structural unit. Dislocations with b = 1/3[111] a and b = 1/2[110] a were observed and inferred to accommodate deviation from the structural unit, respectively. The [110] a, y direction met some of the criteria for an invariant line. Although the OR was explained by geometric criteria it would have been difficult to predict it with such criteria

  3. Microstructure and magnetic properties of yttrium alumina silicate glass microspheres containing iron oxide

    International Nuclear Information System (INIS)

    Sharma, K.; Basak, C.B.; Prajapat, C.L.; Singh, M.R.

    2015-01-01

    Yttrium alumino-silicate glass microspheres have been used for localized delivery of high radiation dose to tissues in the treatment of hepatocellular carcinoma (BCC) and synovitis. 90 Y is a pure beta emitter with beta emission energy of 0.9367 MeV, average penetration range in tissue 2.5 mm, physical half-life of 64.2 h, thus an effective radioisotope for delivering high radiation dose to the tumor. The efficacy of radiotherapy can further be improved if the glass microspheres are doped with magnetic particles for targeted delivery of high radiation dose. Magnetic glass microspheres can also be utilized for cancer treatment using the magnetic heating of tumor cell. The magnetic glass microspheres are obtained from the glasses with nominal composition (64-x) SiO 2 -17Y 2 O 3 -19 Al 2 O 3 -xFe 2 O 3 (x=4-16 mol %). Density of glasses increases from 3.5g/cc to 3.8g/cc as iron oxide content is increased from 4 to 16 mol %. The glass transition temperature and peak crystallization temperature decreases as the iron oxide content increases. T g values of glass samples decreases with increase of Fe 2 O 3 , while SiO 2 content is decreased. SiO 2 is a network forming oxide and a decrease in the network former in glass lead to decrease in thermo-physical properties like T g . The development of ferrimagnetic crystallites in glasses arise from the conversion of iron oxide into magnetite, magnemite and hematite, which is influenced by the structural and ordering of magnetic particles. The microstructure of glass-ceramic exhibited the formation of 50-100 nm size particles. The magnetite and hematite are formed as major crystalline phases. The magnetization values increased with an increase of iron oxide content and attributed to formation of magnetite phase. Results have shown that the glass microspheres with magnetic properties can be used as potential materials for cancer treatment. (author)

  4. Scandium, yttrium and the lanthanides

    International Nuclear Information System (INIS)

    Hart, F.A.

    1987-01-01

    This chapter on the chemistry of the coordination complexes of scandium, yttrium and the lanthanides includes sections on the nitrogen and oxygen donor ligands and complex halides of scandium, and the phosphorus and sulfur donor ligands of yttrium and the lanthanides. Complexes with the macrocylic ligands and with halides are also discussed. Sections on the NMR and electronic spectra of the lanthanides are also included. (UK)

  5. Yttrium-90

    International Nuclear Information System (INIS)

    Ammerich, Marc; Frot, Patricia; Gambini, Denis-Jean; Gauron, Christine; Moureaux, Patrick; Herbelet, Gilbert; Lahaye, Thierry; Pihet, Pascal; Rannou, Alain; Vial, Eric

    2013-03-01

    This sheet belongs to a collection which relates to the use of radionuclides essentially in unsealed sources. Its goal is to gather on a single document the most relevant information as well as the best prevention practices to be implemented. These sheets are made for the persons in charge of radiation protection: users, radioprotection-skill persons, labor physicians. Each sheet treats of: 1 - the radio-physical and biological properties; 2 - the main uses; 3 - the dosimetric parameters; 4 - the measurement; 5 - the protection means; 6 - the areas delimitation and monitoring; 7 - the personnel classification, training and monitoring; 8 - the effluents and wastes; 9 - the authorization and declaration administrative procedures; 10 - the transport; and 11 - the right conduct to adopt in case of incident or accident. This sheet deals specifically with Yttrium-90

  6. Production of yttrium

    International Nuclear Information System (INIS)

    Day, J.G.

    1980-01-01

    A process is described for the production of yttrium metal, or of an alloy comprising a major proportion of yttrium, in which calcium (metal) and yttrium fluoride are reacted together by use of a submerged electric arc in a molten slag. (author)

  7. Unactivated yttrium tantalate phosphor

    International Nuclear Information System (INIS)

    Reddy, V.B.; Cheung, H.K.

    1992-01-01

    This patent describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing one or more additives of Rb and Al in an amount of between about 0.001 to 0.1 moles per mole of yttrium tantalate to improve brightness under X-radiation. This patent also describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing additives of Sr in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate and one or more of Rb and Al in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate the phosphor exhibiting a greater brightness under X-radiation than the phosphor absent Rb and Al

  8. Ultrafiltro de alumina Alumina ultrafilter

    Directory of Open Access Journals (Sweden)

    M. F. de Souza

    1999-06-01

    Full Text Available Membranas de alumina AKP-50 foram preparadas sobre um substrato de alumina APC-SG de alta resistência mecânica. As membranas foram sinterizadas a 1000 °C e possuem uma distribuição estreita de poros de 40 a 90 nm, espessura média de 57 mm e taxa de fluxo de 0,4 m3/m2h. O filtro assim obtido é classificado como ultrafiltro sendo capaz de reter bactérias e alguns vírus. São quimicamente inertes e resistem a temperaturas inferiores a 1000 °C. A aderência entre as camadas permite a limpeza por contra-fluxo.Alumina ceramic membranes with unimodal pore size distribution in the 40 to 90 nm range were prepared on alumina porous substrates. The 57mm thickness membrane made from AKP-50 alumina shows 0,4 m3/m2h flow rate. The two layer substrate, prepared to have high mechanical strength, was made from commercially available APC-SG alumina. The filter made of three layers, membrane, intermediate layer and substrate, is classified as ultra-filter being able to retain bacteria and some viruses. Adherence between the three layers allows reverse washing. Filters are chemically inert and resistant to temperatures below 1000oC.

  9. Diffusion of hydrogen in yttrium

    International Nuclear Information System (INIS)

    Vorobyov, V.V.; Ryabchikov, L.N.

    1966-01-01

    In this work the diffusion coefficients of hydrogen in yttrium were determined from the rate at which the hydrogen was released from yttrium samples under a vacuum at temperatures of 450 to 850 0 C and from the quantity of hydrogen retained by yttrium at hydrogen pressures below 5 x 10 - 4 mm Hg in the same temperature range

  10. Lanthanoid and yttrium tellurates

    Energy Technology Data Exchange (ETDEWEB)

    Gonalez, C G; Guedes de Carvalho, R A [Faculdade de Engenharia, Porto (Portugal). Centro de Engenharia Quimica

    1978-05-01

    Preparation in aqueous medium of all the lanthanoid (except Ce and Pm) and yttrium tellurates is described. Chemical analyses, solubilities at 25/sup 0/C in water and thermograms of all the products prepared were determined. X-ray diffractograms and DTA and DTG curves of La, Gd and Yb tellurates were obtained and commented. Partial volatilization of lanthanoid is observed in the thermal analysis of tellurates.

  11. Synthesis of Alumina using the solvo thermal method

    International Nuclear Information System (INIS)

    Meor Yusoff Meor Sulaiman; Masliana Muslimin

    2007-01-01

    The paper describes work done on synthesis of α- and β-alumina by using the solvo thermal technique. Synthesis of both these aluminas involves the transition reactions of the aluminium hydroxide into alumina by a dehydroxylation process. As there are many forms of transition aluminas produced during this process, x-ray diffraction (XRD) technique was used to identify α-alumina and β-alumina. After establishing the optimum conditions for the production of a single-phase α- and β-aluminas, characteristic study on the product was performed. An important parameter in establishing nano sized powders is their crystallite size and analysis of the β-alumina shows that it is a nano sized powder with a size of 28 nm while the α-alumina has a crystallite size of 200 nm. Other properties analysed include morphology, surface area and particle size. (author)

  12. Atomic structure of surface defects in alumina studied by dynamic force microscopy: strain-relief-, translation- and reflection-related boundaries, including their junctions

    International Nuclear Information System (INIS)

    Simon, G H; König, T; Heinke, L; Lichtenstein, L; Heyde, M; Freund, H-J

    2011-01-01

    We present an extensive atomic resolution frequency modulation dynamic force microscopy study of ultrathin aluminium oxide on a single crystalline NiAl(110) surface. One-dimensional surface defects produced by domain boundaries have been resolved. Images are presented for reflection domain boundaries (RDBs), four different types of antiphase domain boundaries, a nucleation-related translation domain boundary and also domain boundary junctions. New structures and aspects of the boundaries and their network are revealed and merged into a comprehensive picture of the defect arrangements. The alumina film also covers the substrate completely at the boundaries and their junctions and follows the structural building principles found in its unit cell. This encompasses square and rectangular groups of surface oxygen sites. The observed structural elements can be related to the electronic signature of the boundaries and therefore to the electronic defects associated with the boundaries. A coincidence site lattice predicted for the RDBs is in good agreement with experimental data. With Σ = 19 it can be considered to be of low-sigma type, which frequently coincides with special boundary properties. Images of asymmetric RDBs show points of good contact alternating with regions of nearly amorphous disorder in the oxygen sublattice. (paper)

  13. alumina solid electrolyte

    Indian Academy of Sciences (India)

    -β/β -alumina ceramics come from two parent phases designated as β-alumina and β ..... Acknowledgements. This work was supported by the Energy Efficiency & ... of Trade, Industry & Energy, Republic of Korea (No. 20142010102460).

  14. Solvent extraction studies on separation of yttrium from xenotime

    International Nuclear Information System (INIS)

    Singh, D.K.; Anitha, M.; Kain, V.

    2017-01-01

    Rare earths consists a group of 15 element from La to Lu in the periodic table and it also includes Sc and Y since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. The unique physical-chemical properties of the REEs render them important in applications as varies as high strength magnets, lighting phosphors, policing compounds and ceramics. In particular, yttrium finds numerous applications in many areas including superconductors, lasers, phosphors, nuclear reactors, astronavigation, ceramics etc. Yttrium is chemically similar to heavy rare earths (HRE: terbium, dysprosium, erbium, holmium, ytterbium, thulium and lutecium). Yttrium behaves like HRE due to similarity in ionic radius and finds place between Ho and Er. The cross current profile in terms of the plot of concentration of yttrium in raffinate as a function of contact number indicated the complete recovery of rare earths from nitrate solution of xenotime wet cake

  15. Synthesis of alumina/YAG 20 vol% composite by co-precipitation

    Directory of Open Access Journals (Sweden)

    Radosław Lach

    2011-12-01

    Full Text Available Co-precipitation of alumina/YAG precursor from aluminum and yttrium nitrate solution with ammonium carbonate results in dawsonite. Its crystallographic parameters differ from the compound precipitated with no yttrium additive. It suggests that yttrium ions become incorporated into the dawsonite structure. The DSC/TG and X-ray diffraction measurements show decomposition of dawsonite at elevated temperatures resulting in γ-Al2O3 and then δ- and θ-alumina modifications. Full transformation to α-Al2O3 and YAG occurs at temperatures higher than 1230°C. Starting powder for the sintering experiments was prepared using the coprecipitated precursor calcined at 600°C. Seeding of such powder with 5 wt.% α-Al2O3 results in material of 98% density at 1500°C. Much lower densification show compacts of unseeded powder.

  16. Yttrium-90 - ED 4310

    International Nuclear Information System (INIS)

    Ammerich, M.; Frot, P.; Gambini, D.; Gauron, C.; Moureaux, P.; Herbelet, G.; Lahaye, T.; Pihet, P.; Rannou, A.; Vidal, E.

    2013-03-01

    This sheet presents the characteristics of yttrium-90, its origin, and its radio-physical and biological properties. It briefly describes its use in nuclear medicine. It indicates its dosimetric parameters for external exposure, cutaneous contamination, and internal exposure due to acute contamination or to chronic contamination. It indicates and comments the various exposure control techniques: ambient dose rate measurement, surface contamination measurement, atmosphere contamination. It addresses the means of protection: premise design, protection against external exposure and against internal exposure. It describes how areas are delimited and controlled within the premises: regulatory areas, controls to be performed. It addresses the personnel classification, training and medical survey. It addresses the issue of solid and liquid wastes and liquid or gaseous effluents. It briefly recalls the administrative procedures related to the authorization and declaration of possession and use of sealed and unsealed sources. It indicates regulatory aspects related to the transport of yttrium-90, describes what is to be done in case of incident or accident (for the different types of contamination or exposure)

  17. Ionic and molecular transport in beta- and beta''-alumina

    International Nuclear Information System (INIS)

    Bates, J.B.

    1984-03-01

    Investigations of rapid transport of cations and water molecules in the β- and β''-alumina family of superionic conductors are reviewed. Particular topics that are discussed include the Haven ratio and mixed-ion effects in β-alumina, and the influence of superlattice ordering on ionic transport in β''-alumina

  18. Scandium, yttrium and the lanthanide metals

    International Nuclear Information System (INIS)

    Brown, Paul L.; Ekberg, Christian

    2016-01-01

    The hydroxide and oxide phases that exist for scandium(III) include scandium hydroxide, which likely has both amorphous and crystalline forms, ScOOH(s), and scandium oxide. This chapter presents the data selected for the stability constants of the polymeric hydrolysis species of scandium at zero ionic strength. The behaviour of yttrium, and the lanthanide metals, in the environment is largely dependent on their solution equilibria. Hydrolysis and other complexation reactions of yttrium and the lanthanide metals are important in the disposal of nuclear waste. The trivalent lanthanide metals include lanthanum(III) through lutetium(III). A number of studies have reported a tetrad effect for the geochemical behaviour of the lanthanide series, including stability constants and distribution coefficients. The solubility of many of the lanthanide hydroxide phases has been studied at fixed ionic strength. In studying the hydrolysis of cerium(IV), a number of studies have utilised oxidation-reduction reactions in determining the relevant stability constants.

  19. Synthesis of nano γ-alumina by the solvothermal technique

    International Nuclear Information System (INIS)

    Meor Yusoff Meor Sulaiman; Masliana Muslimin

    2006-01-01

    The paper describes work done on synthesis of γ-alumina by using the solvo thermal technique. Synthesis of γ-alumina involves the transition reactions of the aluminium hydroxide into alumina by a dehydroxylation process. As there are many forms of transition aluminas produced during this process, a x-ray diffraction (XRD) technique was used to identify γ-alumina and the other forms of alumina. After establishing the optimum conditions for the production of a single-phase γ-alumina, characteristic study on the product was performed. An important parameter in establishing nanosized powders is their crystallite size and analysis of the γ-alumina shows that it is a nanosized powder with a size of 28 nm. Other properties analysed include morphology, surface area and particle size. (Author)

  20. Porous Alumina Films with Width-Controllable Alumina Stripes

    Directory of Open Access Journals (Sweden)

    Huang Shi-Ming

    2010-01-01

    Full Text Available Abstract Porous alumina films had been fabricated by anodizing from aluminum films after an electropolishing procedure. Alumina stripes without pores can be distinguished on the surface of the porous alumina films. The width of the alumina stripes increases proportionally with the anodizing voltage. And the pores tend to be initiated close to the alumina stripes. These phenomena can be ascribed to the electric field distribution in the alumina barrier layer caused by the geometric structure of the aluminum surface.

  1. Porous Alumina Films with Width-Controllable Alumina Stripes

    Science.gov (United States)

    2010-01-01

    Porous alumina films had been fabricated by anodizing from aluminum films after an electropolishing procedure. Alumina stripes without pores can be distinguished on the surface of the porous alumina films. The width of the alumina stripes increases proportionally with the anodizing voltage. And the pores tend to be initiated close to the alumina stripes. These phenomena can be ascribed to the electric field distribution in the alumina barrier layer caused by the geometric structure of the aluminum surface. PMID:21170406

  2. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate

    International Nuclear Information System (INIS)

    Vasconcelos, Mari Estela de

    2006-01-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  3. Tungsten metallizing alumina--yttria ceramics

    International Nuclear Information System (INIS)

    Cowan, R.E.; Stoddard, S.D.

    1977-03-01

    The ease with which high-alumina bodies may be metallized with tungsten is improved by additions of yttria to the alumina. Mechanisms of this bonding process were studied by use of optical and electron microscopy, electron microprobe, and tensile tests. Variables studied included yttria content of the body and the firing temperature during metallizing. The study showed that a reaction between the tungsten and the yttrogarnet grain boundary phase markedly improved adherence

  4. Everlasting Dark Printing on Alumina by Laser

    Science.gov (United States)

    Penide, J.; Quintero, F.; Arias-González, F.; Fernández, A.; del Val, J.; Comesaña, R.; Riveiro, A.; Lusquiños, F.; Pou, J.

    Marks or prints are needed in almost every material, mainly for decorative or identification purposes. Despite alumina is widely employed in many different industries, the need of printing directly on its surface is still a complex problem. In this sense, lasers have largely demonstrated their high capacities to mark almost every material including ceramics, but performing dark permanent marks on alumina is still an open challenge. In this work we present the results of a comprehensive experimental analysis on the process of marking alumina by laser. Four different laser sources were used in this study: a fiber laser (1075 nm) and three diode pumped Nd:YVO4 lasers emitting at near-infrared (1064 nm), visible (532 nm) and ultraviolet (355 nm) wavelengths, respectively. The results obtained with the four lasers were compared and physical processes involved were explained in detail. Colorimetric analyses allowed to identify the optimal parameters and conditions to produce everlasting and high contrast marks on alumina.

  5. Reuse of activated alumina

    Energy Technology Data Exchange (ETDEWEB)

    Hobensack, J.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Activated alumina is used as a trapping media to remove trace quantities of UF{sub 6} from process vent streams. The current uranium recovery method employs concentrated nitric acid which destroys the alumina pellets and forms a sludge which is a storage and disposal problem. A recently developed technique using a distilled water rinse followed by three dilute acid rinses removes on average 97% of the uranium, and leaves the pellets intact with crush strength and surface area values comparable with new material. Trapping tests confirm the effectiveness of the recycled alumina as UF{sub 6} trapping media.

  6. Coprecipitation of yttrium and aluminium hydroxide for preparation of yttrium aluminium garnet

    NARCIS (Netherlands)

    Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.

    1990-01-01

    Coprecipitation of yttrium and aluminium hydroxide for the preparation of pure yttrium aluminium garnet (YAG) powder with small grain size is the subject of this study. Starting materials are sulphates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3Al5O12), the pH during flocculation

  7. Study on alumina-alumina brazing for application in vacuum chambers of proton synchrotron

    International Nuclear Information System (INIS)

    Yadav, D.P.; Kaul, R.; Ganesh, P.; Shiroman, Ram; Tiwari, Pragya; Sridhar, R.; Kukreja, L.M.

    2013-01-01

    The paper describes an experimental study to standardize vacuum brazing process to obtain satisfactory high purity alumina brazed joints for application in rapid cycle proton synchrotron machine. Two different brazing routes, adopted for making alumina-alumina brazed joints, included (i) multi-step Mo-Mn metallization and brazing with BVAg-8 alloy and (ii) advanced single-step active brazing with CuSil-ABA alloy. Brazed alumina specimens, prepared by both the routes, yielded ultra high vacuum compatible, helium leak tight and bakeable joints. Active-brazed specimens exhibited satisfactory strength values in tensile and four-point bend tests. Metallized-brazed specimens, although exhibited relatively lower tensile strength than the targeted value, displayed satisfactory flexural strength in four-point bend test. The results of the study demonstrated that active brazing is the simple and cost effective alternative to conventional metallization route for producing satisfactory brazed joints for application in rapid cycle proton synchrotron machine. (author)

  8. High alumina refractories

    International Nuclear Information System (INIS)

    Simao, L.C.; Lopes, A.B.; Galvao Filho, N.B.; Souza, R.B. de

    1989-01-01

    High alumina refractories with 92 to 96.5% Al 2 O 3 were produced using brown and white fused as aggregate. Those refractories present only alumina-α and mullite as crystalline mineralogical phase. Other physical and chemical characteristics are similar to the ones found in refractories produced in Brazil, Japan and U.S.A. The most important physical and chemical tests used for the characterization of the raw materials and refractories, complemented by those realized at high temperatures, plus X-ray Difractometry and optical microscopy are presented, besides the refractory formulation and main parameters of production [pt

  9. Improvement of the oxidation resistance of Tribaloy T-800 alloy by the additions of yttrium and aluminium

    International Nuclear Information System (INIS)

    Zhang, Y.-D.; Zhang, C.; Lan, H.; Hou, P.Y.; Yang, Z.-G.

    2011-01-01

    Research highlights: → The additions of yttrium (Y) reduced the oxidation rate of Tribaloy T-800 alloy. → Y promoted selective oxidation of Cr due to refinement of alloy phase size. → The oxidation rate was further reduced by Y plus Al with a protective Al 2 O 3 scale. → The positive effect of Y and Al being more pronounced at the higher temperature. - Abstract: The microstructures and oxidation behaviour of the modified Tribaloy T-800 alloys by additions of yttrium and yttrium plus aluminium have been studied. At the presence of yttrium alone, the oxidation rate decreased, and the selective oxidation of chromium was promoted, which was related to the refinement of alloy phase size. The addition of yttrium plus aluminium further reduced the oxidation rate. The selective oxidation of chromium and aluminium were both promoted significantly. The benefits were especially pronounced at 1000 o C, with the formation of protective alumina external layer and no internal oxides, which may be detrimental to the alloy mechanical property.

  10. Recovery of yttrium from cathode ray tubes and lamps’ fluorescent powders: experimental results and economic simulation

    International Nuclear Information System (INIS)

    Innocenzi, V.; De Michelis, I.; Ferella, F.; Vegliò, F.

    2013-01-01

    Highlights: • Fluorescent powder of lamps. • Fluorescent powder of cathode ray rubes. • Recovery of yttrium from fluorescent powders. • Economic simulation for the processes to recover yttrium from WEEE. - Abstract: In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides. Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%. Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes

  11. Alumina Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2002-02-01

    The Alumina Technology Roadmap outlines a comprehensive long-term research and development plan that defines the industry's collective future and establishes a clear pathway forward. It emphasizes twelve high-priority R&D areas deemed most significant in addressing the strategic goals.

  12. Texture and deformation mechanism of yttrium

    International Nuclear Information System (INIS)

    Adamesku, R.A.; Grebenkin, S.V.; Stepanenko, A.V.

    1992-01-01

    X-ray pole figure analysis was applied to study texture and deformation mechanism in pure and commercial polycrystalline yttrium on cold working. It was found that in cast yttrium the texture manifected itself weakly enough both for pure and commercial metal. Analysis of the data obtained made it possible to assert that cold deformation of pure yttrium in the initial stage occurred mainly by slip the role of which decreased at strains higher than 36%. The texture of heavily deformed commercial yttrium contained two components, these were an 'ideal' basic orientation and an axial one with the angle of inclination about 20 deg. Twinning mechanism was revealed to be also possible in commercial yttrium

  13. Preparation of alumina microspheres

    International Nuclear Information System (INIS)

    Santos, W.R. dos; Abrao, A.

    1980-01-01

    Inorganic exchangers are widely used for adsorption and column partition chromatography. The main difficulty of using commercial alumina (in powder) for column chromatography is related to its packing, and the operations through the column become diffcult and time-consuming; also it turns to be virtually impossible to use large dimension columns. In order to eliminate these problems, a process for the preparation of alumina micro-spheres was developed as an adaptation of a similar process used to prepare nuclear fuel microspheres (UO 2 , ThO 2 ). The flowsheet of this process is presented together with the analytical results of sphericity after calcination, granulometry, density and characterization by X-ray diffractometry. Solubility tests showed that the so-prepared microspheres are well resistant to strong acids and bases; retention tests showed their efficiency, mainly to copper. (C.L.B.) [pt

  14. Radiolabeling Of Albumin Particles With Yttrium-90

    International Nuclear Information System (INIS)

    Nguyen Thi Thu; Nguyen Thi Khanh Giang; Bui Van Cuong, Vo Thi Cam Hoa

    2011-01-01

    This paper presents the process of the radiolabeling of microaggregated albumin particles with radionuclide Yttrium-90 using the directed method. The albumin microsphere kit was prepared in sodium phosphate buffer. The original solution includes 2 mg albumin particle and 0.5 mg stannous chloride dihydrate. The albumin particles size was ranged from 5 ?m to 30 ?m. The mixture was washed three times with phosphate buffer saline, pH 7.2 by centrifugation and suspended in 0.5 M sodium acetate buffer, pH 6. Yttrium - 90 in 1.0 M acetic acid was collected from 90 Sr/ 90 Y generator. The labeling of the particles with Y-90 (185 MBq) was performed at pH 5.5 in acetate buffer with agitating for 60 min at room temperature. The labeled albumin suspensions were centrifuged at 3000 rpm for 15 min. Labeling yields was calculated using centrifugation, filtration and compared with paper chromatography, which is developed in the Tris Acetic EDTA. In this system, the unbound of Y-90 migrates to an R f of 0.9-1.0 and the radiolabeled albumin particles remains at the point of origin (R f = 0). The size of 90 Y-albumin particles was compared with the albumin particles in the original solution to be sure that they did not change during the labeling treatment. The radiolabeling yields were more than 80%. The labeled compound was dialysis in phosphate buffer. The radiochemical purity was 98%. The 90 Y- albumin is an ideal radiopharmaceutical for potential use in malignant cancer treatment as brachytherapy. (author)

  15. Uranyl sorption onto alumina

    International Nuclear Information System (INIS)

    Jacobsson, A.M.M.

    1997-01-01

    The mechanism for the adsorption of uranyl onto alumina from aqueous solution was studied experimentally and the data were modeled using a triple layer surface complexation model. The experiments were carried out at low uranium concentrations (9 x 10 -11 --5 x 10 -8 M) in a CO 2 free environment at varying electrolyte concentrations (0.01--1 M) and pH (4.5--12). The first and second acid dissociation constants, pK a1 and pK a2 , of the alumina surface were determined from potentiometric titrations to be 7.2 ± 0.6 and 11.2 ± 0.4, respectively. The adsorption of uranium was found to be independent of the electrolyte concentration. The authors therefore conclude that the uranium binds as an inner sphere complex. The results were modeled using the code FITEQL. Two reactions of uranium with the surface were needed to fit the data, one forming a uranyl complex with a single surface hydroxyl and the other forming a bridged or bidentate complex reacting with two surface hydroxyls of the alumina. There was no evidence from these experiments of site heterogeneity. The constants used for the reactions were based in part on predictions made utilizing the Hard Soft Acid Base, HSAB, theory, relating the surface complexation constants to the hydrolysis of the sorbing metal ion and the acid dissociation constants of the mineral oxide surface

  16. Reaction of yttrium polonides with carbon dioxide

    International Nuclear Information System (INIS)

    Abakumov, A.S.; Khokhlov, A.D.; Reznikova, N.F.

    1986-01-01

    It has been proved that heating of yttrium and tantalum in carbon dioxide to 500 and 800 0 C alters the gas phase composition, causing formation of carbon monoxide and reduction of oxygen content. A study of the thermal stability of yttrium polonides in carbon dioxide showed that yttrium sesqui- and monopolonides decompose at 400-430 0 C. The temperature dependence of the vapor pressure of polonium obtained upon decomposition of the referred polonides has been determined in a carbon dioxide environment radiotensometrically. The enthalpy of the process calculated from this dependence is close to the enthalpy of vaporization of elemental polonium in vacuo. The mechanism of the reactions has been suggested

  17. A comparative approach to synthesis and sintering of alumina/yttria nanocomposite powders using different precipitants

    Energy Technology Data Exchange (ETDEWEB)

    Kafili, G. [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Movahedi, B., E-mail: b.movahedi@ast.ui.ac.ir [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Milani, M. [Faculty of Advanced Materials and Renewable Energy Research Center, Tehran (Iran, Islamic Republic of)

    2016-11-01

    Alumina/yttria nanocomposite powder as an yttrium aluminum garnet (YAG) precursor was synthesized via partial wet route using urea and ammonium hydrogen carbonate (AHC) as precipitants, respectively. The products were characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectroscopy. The use of urea produced very tiny spherical Y-compounds with chemical composition of Y{sub 2}(CO{sub 3}){sub 3}·nH{sub 2}O, which were attracted to the surface of alumina nanoparticles and consequently, a core-shell structure was obtained. The use of ammonium hydrogen carbonate produced sheets of Y-compounds with chemical composition of Y(OH)CO{sub 3} covering the alumina nanoparticles. A fine-grained YAG ceramic (about 500 nm), presenting a non-negligible transparency (45% RIT at IR range) was obtained by the spark plasma sintering (SPS) of alumina-yttria nanocomposite synthesized in the urea system. This amount of transmission was obtained by only the sintering of the powder specimen without any colloidal forming process before sintering or adding any sintering aids or dopant elements. However, by spark plasma sintering of alumina-yttria nanocomposite powder synthesized in AHC system, an opaque YAG ceramic with an average grain size of 1.2 μm was obtained. - Highlights: • Urea proved to be an appropriate precipitant for obtaining a core-shell alumina/yttria nanocomposite. • Alumina/yttria nanocomposite powders with more appropriate morphology and highly sinterability. • A fine-grained YAG ceramic was obtained by SPS of alumina-yttria nanocomposite.

  18. Yttrium doped BSCF membranes for oxygen separation

    DEFF Research Database (Denmark)

    Haworth, P.; Smart, S.; Glasscock, Julie

    2011-01-01

    This work investigates the partial substitution of yttrium in place of iron in BSCF to form Ba0.5Sr0.5Co0.8Fe0.2−xYxO3−δ, where x varied between 0 and 0.2. X-ray diffraction patterns showed the formation of a perovskite cubic phase structure up to x = 0.15, whilst the full substitution of yttrium...

  19. Crystallization of Yttrium and Samarium Aluminosilicate Glasses

    OpenAIRE

    Lago, Diana Carolina; Prado, Miguel Oscar

    2016-01-01

    Aluminosilicate glasses containing samarium and yttrium (SmAS and YAS glasses) exhibit high glass transition temperatures, corrosion resistance, and glass stability on heating which make them useful for technological applications. Yttrium aluminosilicate glass microspheres are currently being used for internal selective radiotherapy of liver cancer. During the preparation process, crystallization needs to be totally or partially avoided depending on the final application. Thus knowing the cry...

  20. Bauxite Mining and Alumina Refining

    Science.gov (United States)

    Frisch, Neale; Olney, David

    2014-01-01

    Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. Conclusions: A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures. PMID:24806720

  1. Interaction of oxygen vacancies in yttrium germanates

    KAUST Repository

    Wang, Hao

    2012-01-01

    Forming a good Ge/dielectric interface is important to improve the electron mobility of a Ge metal oxide semiconductor field-effect transistor. A thin yttrium germanate capping layer can improve the properties of the Ge/GeO 2 system. We employ electronic structure calculations to investigate the effect of oxygen vacancies in yttrium-doped GeO 2 and the yttrium germanates Y 2Ge 2O 7 and Y 2GeO 5. The calculated densities of states indicate that dangling bonds from oxygen vacancies introduce in-gap states, but the system remains insulating. However, yttrium-doped GeO 2 becomes metallic under oxygen deficiency. Y-doped GeO 2, Y 2Ge 2O 7 and Y 2GeO 5 are calculated to be oxygen substoichiometric under low Fermi energy conditions. The use of yttrium germanates is proposed as a way to effectively passivate the Ge/dielectric interface. This journal is © 2012 the Owner Societies.

  2. Failure Analysis of Alumina Reinforced Aluminum Microtruss and Tube Composites

    Science.gov (United States)

    Chien, Hsueh Fen (Karen)

    The energy absorption capacity of cellular materials can be dramatically increased by applying a structural coating. This thesis examined the failure mechanisms of alumina reinforced 3003 aluminum alloy microtrusses and tubes. Alumina coatings were produced by hard anodizing and by plasma electrolytic oxidation (PEO). The relatively thin and discontinuous oxide coating at the hinge acted as a localized weak spot which triggered a chain reaction of failure, including oxide fracture, oxide spallation, oxide penetration to the aluminum core and severe local plastic deformation of the core. For the PEO microtrusses, delamination occurred within the oxide coating resulting in a global strut buckling failure mode. A new failure mode for the anodized tubes was observed: (i) axisymmetric folding of the aluminum core, (ii) longitudinal fracture, and (iii) alumina pulverization. Overall, the alumina coating enhanced the buckling resistance of the composites, while the aluminum core supported the oxide during the damage propagation.

  3. Kinetics of yttrium dissolution from waste ceramic dust

    OpenAIRE

    STOPIC SRECKO R.; FRIEDRIH BERND G.

    2016-01-01

    Yttrium is a silvery transition metal and has similar chemical properties to lanthanoids. Because of this similarity, yttrium belongs to rare earth elements. Ytttrium and yttrium oxide are mostly used in fluoroscent lamps, production of electrodes, in electronic filters, lasers, superconductors and as additives in various materials to improve their properties. Yttrium is mainly recovered from the minerals monazite [(Ce,La,Th,Nd,Y)PO4] and xenotime YPO4.The presence of radioactive elements suc...

  4. Tungsten - Yttrium Based Nuclear Structural Materials

    Science.gov (United States)

    Ramana, Chintalapalle; Chessa, Jack; Martinenz, Gustavo

    2013-04-01

    The challenging problem currently facing the nuclear science community in this 21st century is design and development of novel structural materials, which will have an impact on the next-generation nuclear reactors. The materials available at present include reduced activation ferritic/martensitic steels, dispersion strengthened reduced activation ferritic steels, and vanadium- or tungsten-based alloys. These materials exhibit one or more specific problems, which are either intrinsic or caused by reactors. This work is focussed towards tungsten-yttrium (W-Y) based alloys and oxide ceramics, which can be utilized in nuclear applications. The goal is to derive a fundamental scientific understanding of W-Y-based materials. In collaboration with University of Califonia -- Davis, the project is designated to demonstrate the W-Y based alloys, ceramics and composites with enhanced physical, mechanical, thermo-chemical properties and higher radiation resistance. Efforts are focussed on understanding the microstructure, manipulating materials behavior under charged-particle and neutron irradiation, and create a knowledge database of defects, elemental diffusion/segregation, and defect trapping along grain boundaries and interfaces. Preliminary results will be discussed.

  5. Studies on yttrium-containing smart alloys

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Felix; Wegener, Tobias; Litnovsky, Andrey; Rasinski, Marcin; Linsmeier, Christian [Forschungszentrum Juelich GmbH, Institut fuer Energie- und Klimaforschung - Plasmaphysik (Germany); Mayer, Joachim [Ernst Ruska-Centrum, 52425 Juelich (Germany)

    2016-07-01

    Tungsten is the main candidate as plasma-facing armour material for future fusion reactors, like DEMO. Advantages of tungsten include high melting point, high thermal conductivity, low tritium retention, and low erosion yield. A problem is oxide volatilisation under accidental conditions where the temperature of the first wall can reach 1200 K to 1450 K and air ingress occurs. Therefore smart tungsten alloys are developed. Smart alloys are supposed to preserve properties of tungsten during plasma operation coupled with suppressed tungsten oxide formation in case of an accident. Lab-scale tungsten-chromium-yttrium (W-Cr-Y) samples prepared by magnetron sputtering are used as model system. The mechanisms of oxidation and its dynamics are studied using a thermogravimetric system, focussed ion beam, and electron microscopy. A composition scan was conducted: The new material composition featuring W, ∝ 12 wt.% Cr, ∝ 0.3 wt.% Y showed strongest suppression of oxidation, no pores, and least internal oxidation. At 1273 K in argon-oxygen atmosphere an oxidation rate of 3 . 10{sup -6} mg{sup 2}cm{sup -4}s{sup -1} was measured. At 1473 K ternary W-Cr-Y alloys suppressed evaporation up to 20 min while for W-Cr evaporation was already evident after 5 min. Comparison of passivation in dry and humid atmosphere, at temperatures of 1073 K to 1473 K is performed.

  6. Yttrium-90 microsphere induced gastrointestinal tract ulceration

    Directory of Open Access Journals (Sweden)

    Rikabi Ali A

    2008-09-01

    Full Text Available Abstract Background Radiomicrosphere therapy (RT utilizing yttrium-90 (90Y microspheres has been shown to be an effective regional treatment for primary and secondary hepatic malignancies. We sought to determine a large academic institution's experience regarding the extent and frequency of gastrointestinal complications. Methods Between 2004 and 2007, 27 patients underwent RT for primary or secondary hepatic malignancies. Charts were subsequently reviewed to determine the incidence and severity of GI ulceration. Results Three patients presented with gastrointestinal bleeding and underwent upper endoscopy. Review of the pretreatment angiograms showed normal vascular anatomy in one patient, sclerosed hepatic vasculature in a patient who had undergone prior chemoembolization in a second, and an aberrant left hepatic artery in a third. None had undergone prophylactic gastroduodenal artery embolization. Endoscopic findings included erythema, mucosal erosions, and large gastric ulcers. Microspheres were visible on endoscopic biopsy. In two patients, gastric ulcers were persistent at the time of repeat endoscopy 1–4 months later despite proton pump inhibitor therapy. One elderly patient who refused surgical intervention died from recurrent hemorrhage. Conclusion Gastrointestinal ulceration is a known yet rarely reported complication of 90Y microsphere embolization with potentially life-threatening consequences. Once diagnosed, refractory ulcers should be considered for aggressive surgical management.

  7. Novel Translucent and Strong Submicron Alumina Ceramics for Dental Restorations.

    Science.gov (United States)

    Zhao, M; Sun, Y; Zhang, J; Zhang, Y

    2018-03-01

    An ideal ceramic restorative material should possess excellent aesthetic and mechanical properties. We hypothesize that the high translucency and strength of polycrystalline ceramics can be achieved through microstructural tailoring. The aim of this study is to demonstrate the superior optical and mechanical properties of a new class of submicron grain-sized alumina ceramics relative to the current state-of-the-art dental ceramic materials. The translucency, the in-line transmission ( T IT ) in particular, of these submicron alumina ceramics has been examined with the Rayleigh-Gans-Debye light-scattering model. The theoretical predictions related very well with the measured T IT values. The translucency parameter ( TP) and contrast ratio ( CR) of the newly developed aluminas were measured with a reflectance spectrophotometer on a black-and-white background. For comparison, the T IT , TP, and CR values for a variety of dental ceramics, mostly measured in-house but also cited from the literature, were included. The flexural strength of the aluminas was determined with the 4-point bending test. Our findings have shown that for polycrystalline alumina ceramics, an average grain size ceramic and zirconias, including the most translucent cubic-containing zirconias. The strength of these submicron grain-sized aluminas was significantly higher than that of the cubic-containing zirconia (e.g., Zpex Smile) and lithia-based glass-ceramics (e.g., IPS e.max CAD HT). A coarse-grained alumina could also reach a translucency level comparable to that of dental porcelain. However, the relatively low strength of this material has limited its clinical indications to structurally less demanding applications, such as orthodontic brackets. With a combined high strength and translucency, the newly developed submicron grain-sized alumina may be considered a suitable material for dental restorations.

  8. Development of 2024 AA-Yttrium composites by Spark Plasma Sintering

    Science.gov (United States)

    Vidyasagar, CH S.; Karunakar, D. B.

    2018-04-01

    The method of fabrication of MMNCs is quite a challenge, which includes advanced processing techniques like Spark Plasma Sintering (SPS), etc. The objective of the present work is to fabricate aluminium based MMNCs with the addition of small amounts of yttrium using Spark Plasma Sintering and to evaluate their mechanical and microstructure properties. Samples of 2024 AA with yttrium ranging from 0.1% to 0.5 wt% are fabricated by Spark Plasma Sintering (SPS). Hardness of the samples is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FE-SEM). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with those of the composite developed. It is found that the yttrium addition increases the above mentioned properties by altering the precipitation kinetics and intermetallic formation to some extent and then decreases gradually when yttrium wt% increases beyond 0.3 wt%. High density (˂ 99.75) is achieved in the samples and highest hardness achieved is 114 Hv, fabricated by spark plasma sintering and uniform distribution of yttrium is observed.

  9. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  10. Features of solid solutions composition in magnesium with yttrium alloys

    International Nuclear Information System (INIS)

    Drits, M.E.; Rokhlin, L.L.; Tarytina, I.E.

    1983-01-01

    Additional data on features of yttrium solid solutions composition in magnesium in the course of their decomposition investigation in the case of aging are obtianed. The investigation has been carried out on the base of a binary magnesium-yttrium alloy the composition of which has been close to maximum solubility (at eutectic temperature) and magnesium-yttrium alloys additionally doped with zinc. It is shown that higher yttrium solubility in solid magnesium than it has been expected, issueing from the difference in atomic radii of these metals indicates electron yttrium-magnesium atoms interaction. In oversaturated magnesium-yttrium solid solutions at earlier decomposition stages Mg 3 Cd type ordering is observed. At aging temperatures up to 250 deg C and long exposures corresponding to highest strengthening in oversaturated magnesium yttrium solid solutions a rhombic crystal lattice phase with three symmetric orientations is formed

  11. Physicochemical analysis of cryocrystallization processes of aqueous solutions of yttrium, barium, copper nitrates and their mixtures

    International Nuclear Information System (INIS)

    Kulakov, A.B.; Mozhaev, A.P.; Tesker, A.M.; Churagulov, B.R.

    1992-01-01

    Products of fast hardening of aqueous solutions of different concentration of yttrium, barium copper nitrates and their mixtures including mixture of three nitrates with molar ratio equal to 1:2:3 used for synthesis of YBa 2 Cu 3 O 7-x HTSC by cryochemical technique, in liquid nitrogen, are studied using low-temperature, differential thermal and X-ray phase analyses. Aqueous solutions of barium, copper, yttrium nitrates are shown to belong to three different classes which differ in behaviour at fast cooling and subsequent slow heating. Cryogranulate at YBa 2 Cu 2 O 7-x synthesis using cryochemical technique represents mixture of X-ray amorphous Ba(NO 3 ) 2 , crystalline Cu(NO 3 ) 2 ·6H 2 O and ice, as well as, supercooled aqueous solution of yttrium and copper nitrates

  12. Method for production of transparent yttrium oxide

    International Nuclear Information System (INIS)

    Dutta, S.K.; Gazza, G.A.

    1975-01-01

    The method comprises vacuum hot pressing the yttrium oxide (Y 2 O 3 ) powder in a graphite die at temperatures of between 1300 to 1500 0 C and uniaxial pressures of between 5000 to 7000 psi, for a period of 1 to 2 hours. (U.S.)

  13. Method for chromatographically recovering scandium and yttrium

    International Nuclear Information System (INIS)

    Snyder, T.S.; Stoltz, R.A.

    1991-01-01

    This paper describes a method for chromatographically recovering scandium and yttrium from the residue of a sand chlorinator. It comprises: providing a residue from a sand chlorinator, the residue containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; digesting the residue with an acid to produce an aqueous liquid containing scandium, yttrium, sodium, calcium and at least one radioactive metal of the group consisting of radium, thorium and uranium; feeding the metal containing liquid through a cation exchanger; eluding the cation exchanger with an acid eluant to to produce: a first eluate containing at least half of the total weight of the calcium and sodium in the feed liquid; a second eluate containing at least half of the total weight of the one or more radioactive metals in the feed liquid; a third eluate containing at least half of the yttrium in the feed liquid, and a fourth eluate containing at least half of the weight of the scandium in the feed liquid

  14. New hydrotalcite-like compounds containing yttrium

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.M.; Barriga, C.; Ulibarri, M.A. [Universidad de Cordoba (Spain)] [and others

    1997-01-01

    The synthesis of hydrotalcite-type compounds containing yttrium was carried out by the coprecipitation of Mg(II), Al(III), and Y(III) cations at 60 degrees C with strong alkaline solutions. Thermal treatments were applied and changes studied.

  15. Fabrication of asymmetric alumina membranes

    International Nuclear Information System (INIS)

    Firouzghalb, H.; Falamaki, C.

    2010-01-01

    The effect of SrO addition on the thermal stabilization of transition aluminas with the aim of producing membrane layers (supported and unsupported) has been investigated. Al 2 O 3 -x wt.% SrO composite powders (x = 1, 3, 5, 8) were synthesized by co-precipitation of the hydroxides from solutions of AlCl 3 and Sr(NO 3 ) 2 salts using NH 4 OH as a precipitating agent. Optimum SrO dopant concentration regarding the transition aluminas stabilization effect was determined to be 5 wt.% based on XRD analysis. STA analysis showed a 30 deg. C shift versus higher temperatures in the transformation of final transitional alumina (θ-Al 2 O 3 ) to stable alpha phase due to addition of 5 wt.% SrO. The mechanism of transition aluminas thermal stabilization as a result of SrO addition is thoroughly discussed. Unsupported alumina membranes were prepared by drying boehmite sols at 600, 800, 1000 and 1100 deg. C. The effect of calcination temperature on surface area, pore size distribution of unsupported membranes containing 5 wt.% SrO has been investigated. The microstructure of unsupported and supported membranes revealed quite different. Smaller grains in the supported layers were attributed to the interaction between support and membrane.

  16. Gelcasting polycrystalline alumina

    Energy Technology Data Exchange (ETDEWEB)

    Janney, M.A. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    This work is being done as part of a CRADA with Osram-Sylvania, Inc. (OSI) OSI is a major U.S. manufacturer of high-intensity lighting. Among its products is the Lumalux{reg_sign} line of high-pressure sodium vapor arc lamps, which are used for industrial, highway, and street lighting. The key to the performance of these lamps is the polycrystalline alumina (PCA) tube that is used to contain the plasma that is formed in the electric arc. That plasma consists of ionized sodium, mercury, and xenon vapors. The key attributes of the PCA tubes are their transparency (95% total transmittance in the visible region), their refractoriness (inner wall temperature can reach 1400{degrees}C), and their chemical resistance (sodium and mercury vapor are extremely corrosive). The current efficiency of the lamps is very high, on the order of several hundred lumens / watt. (Compare - incandescent lamps -13 lumens/watt fluorescent lamps -30 lumens/watt.) Osram-Sylvania would like to explore using gelcasting to form PCA tubes for Lumalux{reg_sign} lamps, and eventually for metal halide lamps (known as quartz-halogen lamps). Osram-Sylvania, Inc. currently manufactures PCA tubes by isostatic pressing. This process works well for the shapes that they presently use. However, there are several types of tubes that are either difficult or impossible to make by isostatic pressing. It is the desire to make these new shapes and sizes of tubes that has prompted Osram-Sylvania`s interest in gelcasting. The purpose of the CRADA is to determine the feasibility of making PCA items having sufficient optical quality that they are useful in lighting applications using gelcasting.

  17. Alumina Yield in the Bayer Process

    Science.gov (United States)

    Den Hond, R.

    The alumina industry has historically been able to reduce alumina production costs, by increasing the liquor alumina yield. To know the potential for further yield increases, the phase diagram of the ternary system Na2O-Al2O -H2O at various temperature levels was analysed. It was found that the maximum theorical precipitation alumina yield is 160 g/l, while that for digestion was calculated to be 675 g/l.

  18. Attrition resistant gamma-alumina catalyst support

    Science.gov (United States)

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2006-03-14

    A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

  19. Sintering behaviour of spinel–alumina composites

    Indian Academy of Sciences (India)

    % alumina dissolves in spinel (MgAl2O4) at 1600°C. Solid solubility of alumina in spinel decreases rapidly with decreasing temperature, which causes exsolution of alumina from spinel phase. Previous work of one of the authors revealed that ...

  20. Dynamic tensile response of alumina-Al composites

    International Nuclear Information System (INIS)

    Atisivan, R.; Bandyopadhyay, A.; Gupta, Y. M.

    2002-01-01

    Plate impact experiments were carried out to examine the high strain-rate tensile response of alumina-aluminum (Al) composites with tailored microstructures. A novel processing technique was used to fabricate interpenetrating phase alumina-aluminum composites with controlled microstructures. Fused deposition modeling (FDM), a commercially available rapid prototyping technique, was used to produce the controlled porosity mullite ceramic preforms. Alumina-Al composites were then processed via reactive metal infiltration of porous mullite ceramics. With this approach, both the micro as well as the macro structures can be designed via computer aided design (CAD) to tailor the properties of the composites. Two sets of dynamic tensile experiments were performed. In the first, the metal content was varied between 23 and 39 wt. percent. In the second, the microstructure was varied while holding the metal content nearly constant. Samples with higher metal content, as expected, displayed better spall resistance. For a given metal content, samples with finer metal diameter showed better spall resistance. Relationship of the microstructural parameters on the dynamic tensile response of the structured composites is discussed here

  1. Transport properties of alumina nanofluids

    International Nuclear Information System (INIS)

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-01-01

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 deg. C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m -1 K -1 was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 deg. C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at various

  2. Magnetic structure of holmium-yttrium superlattices

    DEFF Research Database (Denmark)

    Jehan, D.A.; McMorrow, D.F.; Cowley, R.A.

    1993-01-01

    We present the results of a study of the chemical and magnetic structures of a series of holmium-yttrium superlattices and a 5000 angstrom film of holmium, all grown by molecular-beam epitaxy. By combining the results of high-resolution x-ray diffraction with detailed modeling, we show...... that the superlattices have high crystallographic integrity: the structural coherence length parallel to the growth direction is typically almost-equal-to 2000 angstrom, while the interfaces between the two elements are well defined and extend over approximately four lattice planes. The magnetic structures were...... determined using neutron-scattering techniques. The moments on the Ho3+ ions in the superlattices form a basal-plane helix. From an analysis of the superlattice structure factors of the primary magnetic satellites, we are able to determine separately the contributions made by the holmium and yttrium...

  3. Treatment of acromegaly by yttrium implantation

    Energy Technology Data Exchange (ETDEWEB)

    Hibbert, J.; Shaheen, O.H.

    1977-01-01

    Yttrium implantation is one of the many ways of treating acromegaly. The advantages are the minor nature of the procedure and the fact that pituitary replacement is not as commonly required as after hypophysectomy. Thus in young female patients menstruation may be resumed following treatment and pregnancy has occurred. The procedure is not as free from complications as external irradiation but the response is more satisfactory.

  4. Yttrium and rare earths separation by ion exchange resin

    International Nuclear Information System (INIS)

    Pinatti, D.G.; Ayres, M.J.G.; Ribeiro, S.; Silva, G.L.J.P.; Silva, M.L.C.P.; Martins, A.H.

    1988-01-01

    The experimental results of yttrium and rare earths separation from Brazilian xenotime are presented. The research consist in five stage: 1) Preparation of yttrium, erbium and lutetium standard solutions, from solubilization of pure oxides 2) yttrium and rare earths separation by ion exchange chromatrography 3) Separation and recovery of EDTA 4) Precipitation and calcination and 4) Analytical control of process. (C.G.C.) [pt

  5. Yttrium addition for high temperatures stainless steel

    International Nuclear Information System (INIS)

    Furtado, Nelson Cesar Chaves Pinto

    1997-07-01

    The current work studied the effect of Yttrium on the microstructure of 2% Nb, modified - HP steel, with respect to its mechanical properties. Alloys were prepared with nominal Yttrium additions of 0,1% and 0,25%. Microstructural analyses and mechanical tests were undertaken in the as-cast condition and after ageing for 100 h at 700 deg C, 900 deg C and 1100 deg C. Structural characterization was performed by optical microscopy, scanning and transmission electron microscopy (SEM/TEM/EDS), X-ray diffractometry and X-ray photoelectron spectroscopy (XPS). Tensile testing was performed at room temperature and 871 deg C and creep testing at 925 deg C at a loading of 55 MPa. The material produced exhibited superior mechanical properties and surface oxidation resistance than traditional alloys of this class, even through gravity cast in a magnetic furnace. Agglomerates of Yttrium-rich phases were identifies in both as-cast and aged specimens, always associated with chromium carbides of characteristic morphologies. These morphologies, combined with the microstructural constituents, may have established the factors which resulted in the improved metallurgical stability of these alloys under the experimental testing conditions and temperatures which simulated real industrial service conditions and temperatures. (author)

  6. Yttrium aluminum garnet coating on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J., E-mail: eduardo.nassar@unifran.edu.br

    2016-02-15

    Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu{sup 3+} onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min{sup −1} and evaporation led to deposition of different numbers of layers of the YAG:Eu{sup 3+} film onto the glass substrate from a YAG:Eu{sup 3+} powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu{sup 3+}. • The matrix was deposited as transparent films. • The YAG:Eu{sup 3+} was deposited by sol–gel process onto glass substrate.

  7. Yttrium aluminum garnet coating on glass substrate

    International Nuclear Information System (INIS)

    Ferreira, Camila M.A.; Freiria, Gabriela S.; Faria, Emerson H. de; Rocha, Lucas A.; Ciuffi, Katia J.; Nassar, Eduardo J.

    2016-01-01

    Thin luminescent films have seen great technological advances and are applicable in the production of a variety of materials such as sensors, solar cells, photovoltaic devices, optical magnetic readers, waveguides, lasers, and recorders. Systems that contain yttrium aluminum oxide are important hosts for lanthanide ions and serve as light emission devices. This work deals with the deposition of yttrium aluminum garnet (YAG) film doped with Eu 3+ onto a glass substrate obtained by the sol–gel methodology. Spray pyrolysis furnished the yttrium aluminum oxide powder. Dip-coating at a withdrawal speed of 10 mm min −1 and evaporation led to deposition of different numbers of layers of the YAG:Eu 3+ film onto the glass substrate from a YAG:Eu 3+ powder suspension containing ethanol, water, and tetraethylorthosilicate. Photoluminescence, X-ray diffraction, scanning electron microscopy, and transparency measurements aided film characterization. The emission spectra revealed that the number of layers influenced film properties. - Highlights: • The spray pyrolysis was used to obtain luminescent YAG:Eu 3+ . • The matrix was deposited as transparent films. • The YAG:Eu 3+ was deposited by sol–gel process onto glass substrate.

  8. Zirconia dispersion as a toughening agent in alumina - Influence of the cerium oxide

    International Nuclear Information System (INIS)

    Gritti, Olivier

    1987-01-01

    The improvement of mechanical properties of alumina can be obtained by fine dispersion of zirconia particles. The addition of cerium oxide as a stabilizer of the tetragonal phase has been examined. Different powder preparations, based on impregnation of the alumina powder by zirconium and cerium precursor salts, have been studied. Parameters, such as properties of alumina powder and cerium oxide content, for the production of reactive powders have been determined by two laboratory processes. The sintering of these powders in air at 1600 deg. C has resulted in dense materials with homogeneous microstructure. The mechanical properties, in particular the biaxial flexure strength and the toughness, have been determined in the temperature range 20 deg. C-900 deg. C. A reinforcement of about 80 pc in comparison with alumina is achieved. The optimal composition is (Al 2 O 3 ) 0.8 (ZrO 2 ) 0.18 (CeO 2 ) 0.02 . In the other hand, powder preparation by spray drying has been chosen for an approach to a larger scale process. The sintered ceramics made with these powders present a double microstructure which does not affect the mechanical properties. The presence of cerium oxide produces the following improvements: - increased mobility of the intergranular zirconia inclusions which results in a faster densification; - stabilization of a tetragonal phase without prohibiting the stress induced transformation; - increase of the critical sizes of the tetragonal → monoclinic transformation; - a large decrease in the transformation kinetic in water at 300 deg. C in comparison with that observed for alumina-zirconia doped with yttrium oxide. (author) [fr

  9. Development and evaluation of alumina calcination

    International Nuclear Information System (INIS)

    Bennett, I.J.

    2000-01-01

    This thesis focuses on a number of aspects governing the transformation of gibbsite, via intermediate phases, to α-alumina. These aspects include the size and morphology of the gibbsite grains, the influence of additions of foreign elements, the effect of a mechanical treatment of the gibbsite prior to calcination, and combinations of these factors. The materials were characterised by scanning electron microscopy, X-ray diffraction and surface area measurements. For some of the calcined materials an attempt was made to sinter the powders to a dense body to investigate if any of the treatments during calcination had an effect on this process. The literature review covers the current state of understanding of the production of bulk alumina powder by the Bayer process and the phase changes seen on calcination of precursors to the stable α-alumina phase. A detailed description of the phase changes is given and the various routes and conditions necessary for the transformations to occur are considered. The transformations are examined in relation to the morphology of the crystals and the variables controlling the phase transformation route are discussed. Calcination in air showed that the size of the gibbsite grain governs the calcination route taken to reach oc-alumina. The standard gibbsites used in this work show a mixed calcination sequence transforming both via the boehmite phase, followed by the γ, δ and θ phases, and via the χ and κ phases. The formation of boehmite is attributed to retention of water vapour within the grain. Differences in morphology of the starting materials showed that for the range of materials seen, the morphology of the grain is less important than its size. The super fine material confirmed that a small grain size transforms via the non-boehmite route only, with the other gibbsites taking intermediate routes as for the standard gibbsites. Of the additions made prior to calcination, aluminium fluoride was found to reduce the

  10. A High-Purity Alumina for Use in Studies of Shock Loaded Samples

    Science.gov (United States)

    Lacina, David; Neel, Christopher

    2017-06-01

    We report the results of plate impact experiments on a potential new ``standard'' material, Coorstek Plasmapure-UC (99.9% purity) polycrystalline alumina, for use in non-conduction, impact environment, shock loading studies. This work was motivated by a desire to find a 99.9% purity alumina to replace the now unavailable Coors Vistal (99.9%) alumina, as it was hoped the Hugoniot elastic limit (HEL) of the new standard would match the 9-11 GPa value of Vistal. Shock response data, including the HEL, Hugoniot particle velocities, Hugoniot shock velocities, stress vs volume, and release wave speeds, was obtained up to 14 GPa. This data will be compared with Hugoniot curve data for other high purity alumina to contrast differences in the shock response, and is intended to be useful in impedance matching calculations. We will show that the HEL of Plasmapure-UC alumina is 5.5 GPa and speculate on causes for this lower than expected value. We will also explore why the elastic-plastic response for Plasmapure-UC alumina differs from what has been observed from other high purity alumina. The final result of this work is to recommend a well-characterized, lower purity alumina (Coorstek AD-995) as a potential new ``standard'' material.

  11. The examination of calcium ion implanted alumina with energy filtered transmission electron microscopy

    International Nuclear Information System (INIS)

    Hunt, E.M.; Hampikian, J.M.

    1997-01-01

    Ion implantation can be used to alter in the optical response of insulators through the formation of embedded nano-sized particles. Single crystal alumina has been implanted at ambient temperature with 50 keV Ca + to a fluence of 5 x 10 16 ions/cm 2 . Ion channeling, Knoop microhardness measurements, and transmission electron microscopy (TEM) indicate that the alumina surface layer was amorphized by the implant. TEM also revealed nano-sized crystals ∼7--8 nm in diameter. These nanocrystals are randomly oriented, and exhibit a face-centered cubic structure (FCC) with a lattice parameter of 0.409 nm ± 0.002 nm. The similarity between this crystallography and that of pure aluminum suggests that they are metallic aluminum nanocrystals with a slightly dilated lattice parameter, possibly due to the incorporation of a small amount of calcium. Energy-filtered transmission electron microscopy (EFTEM) provides an avenue by which to confirm the metallic nature of the aluminum involved in the nanocrystals. EFTEM has confirmed that the aluminum present in the particles is metallic in nature, that the particles are oxygen deficient in comparison with the matrix material and that the particles are deficient in calcium, and therefore not likely to be calcia. The particles thus appear to be FCC Al (possibly alloyed with a few percent Ca) with a lattice parameter of 0.409nm. A similar result was obtained for yttrium ion implantation into alumina

  12. Sol gel synthesis for preparation of yttrium aluminium garnet

    NARCIS (Netherlands)

    Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.; With, de G.; Terpstra, R.A.; Metselaar, R.

    1989-01-01

    Sol-gel—synthesis for preparation of pure yttrium aluminium garnet powder with small grain size is subject of this ongoing study. Starting materials were sulfates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3A1SO1Z) pH during hydrolysis as well as temperature during calcination and

  13. Bauxite Mining and Alumina Refining

    OpenAIRE

    Donoghue, A. Michael; Frisch, Neale; Olney, David

    2014-01-01

    Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust,...

  14. Production of pure sintered alumina

    International Nuclear Information System (INIS)

    Rocha, J.C. da; Huebner, H.W.

    1982-01-01

    With the aim of optimizing the sintering parameters, the strength of a large number of alumina samples was determined which were produced under widely varying sintering conditions and with different amounts of MgO content. The strength as a function of sintering time or temperature was found to go through a maximum. With increasing time, this maximum is shifted to lower temperatures, and with decreasing temperature to longer times. Data pairs of sintering times and temperatures which yeld the strength maximum were determined. The value of the strength at the maximum remains unchanged. The strength is high (= 400 MN/m 2 , at a grain size of 3 um and a porosity of 2 per cent) and comparable to foreign aluminas produced for commercial purposes, or even higher. The increase in the sintering time from 1 h to 16 h permits a reduction of the sintering temperature from 1600 to 1450 0 C without losing strength. The practical importance of this fact for a production of sintered alumina on a large scale is emphasized. (Author) [pt

  15. Abscopal Effects and Yttrium-90 Radioembolization

    Energy Technology Data Exchange (ETDEWEB)

    Ghodadra, Anish; Bhatt, Sumantha [University Pittsburgh School of Medicine, Department of Radiology (United States); Camacho, Juan C. [Emory University School of Medicine, Department of Radiology and Imaging Sciences (United States); Kim, Hyun S., E-mail: kevin.kim@yale.edu [University Pittsburgh School of Medicine, Department of Radiology (United States)

    2016-07-15

    We present the case of an 80-year-old male with squamous cell carcinoma with bilobar hepatic metastases who underwent targeted Yttrium-90 radioembolization of the right hepatic lobe lesion. Subsequently, there was complete regression of the nontargeted, left hepatic lobe lesion. This may represent the first ever reported abscopal effect in radioembolization. The abscopal effect refers to the phenomenon of tumor response in nontargeted sites after targeted radiotherapy. In this article, we briefly review the immune-mediated mechanisms responsible for the abscopal effect.

  16. Nonlinear FMR spectra in yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

    2015-12-01

    Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

  17. Cerium and yttrium oxide nanoparticles are neuroprotective

    International Nuclear Information System (INIS)

    Schubert, David; Dargusch, Richard; Raitano, Joan; Chan, S.-W.

    2006-01-01

    The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems

  18. The spectrum of singly ionized yttrium, Y II

    International Nuclear Information System (INIS)

    Nilsson, A.E.; Johansson, S.; Kurucz, R.L.

    1991-01-01

    Hollow-cathode spectra of yttrium have been registered in the wavelength region 1000-48800 A. Resonant charge transfer reactions in the light source favour the excitation of Y II, where 174 new levels have been established by means of 1284 newly classified lines. Altogether we report 1521 lines between 235 levels in Y II. The ground complex (4d+5s) 2 is now completely known and a number of Rydberg series have been extended. The new levels belong to the 4dnl (nl=7s, 8s, 9s, 6p, 7p, 4d, 5d, 6d, 7d, 8d, 4f, 5f, 6f, 7f, 5g) and 5snl (nl=7s, 8s, 6p, 6d, 4f, 5f) configurations. Eigenvector compositions, based on paramagnetic calculations including configuration interaction, are given for all levels. The ionization limit has been determined to 98590 ± 5 cm -1 . (orig.)

  19. Yttrium synovectomy: a meta-analysis of the literature

    International Nuclear Information System (INIS)

    Jones, G.

    1993-01-01

    Yttrium synovectomy for chronic synovitis of the knee enjoys widespread usage in Australia with approximately 400 patients receiving yttrium-90 in 1991. Despite abundant anecdotal evidence of its efficacy there is a paucity of controlled trials and those that have been done have produced conflicting results and have been of insufficient sample size. To critically and quantitatively evaluate the published English literature on comparative trials of yttrium-90 therapy for chronic synovitis of the knee, the technique of meta-analysis was utilised. The literature search was carried out using the MeSH terms of synovectomy and knee; and yttrium. This was augmented by referring to reviews, current textbooks and back-references. Outcome measures varied between trials but could be grouped as treatment success. The Peto modification of Mantel and Haenszl was used for statistical pooling of data yielding a pooled odds ratio (OR). The literature search revealed ten controlled trials of which two were excluded from further analysis. It was found that yttrium was superior to placebo (OR 2.42, 95% CI 1.02-5.73) but it is recommended that this result should be interpreted with caution due to possible publication bias. It is concluded that there is insufficient evidence from comparative trials of yttrium in the English literature to show that yttrium synovectomy is convincingly superior to triamcinolone (OR 1.89, 95% CI 0.81-10.55) or other active modalities (OR 1.04, 95% CI 0.72-1.52). 25 refs., 4 tabs

  20. A novel technique for synthesizing dense alumina nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Pancholi, A [Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States); Stoleru, V G [Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States); Kell, C D [Department of Chemical Engineering, University of Delaware, Newark, DE 19716 (United States)

    2007-05-30

    The formation of highly ordered nanoporous alumina membranes by anodizing high-purity aluminium under optimum conditions (i.e., anodization time, electrolyte temperature, and cell voltage) in various electrolyte solutions is a well established process. In this paper we report on the formation of a wide range of alumina nanostructures, including nanotubes/nanochannels, nanoplates, and nanofibres, by using a technique that involves anodization and etching processing steps similar to the ones that yield nanopores, under slightly modified experimental conditions. The effects of the anodization voltage, time, and temperature, as well as the effects of the etching time, on the formation and the properties of the alumina nanostructures are analysed. We propose a simple analytical model to describe the formation of different types of alumina nanostructures, as a result of irreversible breakage of the pore walls for long etching times. The geometry of the nanostructures and their dimensions, ranging between 10 and 100 nm, were found to be dependent on the pore dimensions and on the location of the cleavage/breakage of the pore walls.

  1. Preparation of alumina-β'

    International Nuclear Information System (INIS)

    Casarini, J.R.; Souza, D.P.F.

    1984-01-01

    Alumina - (β + β') in powder, with composition of 8.85% Na 2 0 + 0.75% Li 2 0 + 90.40% Al 2 O 3 is obtained using the zeta process. The phase transformation β→β' can be seen with powder X-ray diffraction. It was observed that the efficiency of the transformation is related to the processing and purity of the raw material. Impurities as Ca and Si difficult the phase transformation β→β'. (E.G.) [pt

  2. Characterization of the Sol-Gel Transition for Zirconia-Toughened Alumina Precursors

    Science.gov (United States)

    Moeti, I.; Karikari, E.; Chen, J.

    1998-01-01

    High purity ZTA ceramic powders with and without yttria were produced using metal alkoxide precursors. ZTA ceramic powders with varying volume percents of zirconia were prepared (7, 15, and 22%). Aluminum tri-sec butoxide, zirconium propoxide, and yttrium isopropoxide were the reagents used. Synthesis conditions were varied to control the hydrolysis and the aging conditions for the sol to gel transition. FTIR analysis and theological characterization were used to follow the structural evolution during the sol to gel transition. The greater extent of hydrolysis and the build-up of structure measured from viscoelastic properties were consistent. Heat treatment was conducted to produce submicron grain fully crystalline ZTA ceramic powders. In all experimental cases a-alumina and tetragonal zirconia phases were confirmed even in the absence of yttria.

  3. Microencapsulation of silicon nitride particles with yttria and yttria-alumina precursors

    International Nuclear Information System (INIS)

    Garg, A.K.; De Jonghe, L.C.

    1990-01-01

    Procedures are described to deposit uniform layers of yttria and yttria-alumina precursors on fine powders and whiskers of silicon nitride. The coatings were produced by aging at elevated temperatures aqueous systems containing the silicon nitride core particles, yttrium and aluminum nitrates, and urea. Optimum concentrations of the core particles, in relation to the reactants, were established to promote surface deposition of the oxide precursors. Polymeric dispersants were used effectively to prevent agglomeration of the solids during the microencapsulation process. The morphology of the powders was characterized using scanning and transmission electron microscopy. The mechanisms for the formation of the coated layers are discussed. A description is provided that allows qualitative assessment of the experimental factors that determine microencapsulation by a slurry method

  4. Ordering of Octahedral Vacancies in Transition Aluminas

    NARCIS (Netherlands)

    Wang, Yuan Go; Bronsveld, Paul M.; Hosson, Jeff Th.M. De; Djuričić, Boro; McGarry, David; Pickering, Stephen

    1998-01-01

    The microstructure of transition aluminas obtained via the dehydration of boehmite has been characterized by using transmission electron microscopy (TEM). The presence of γ-, δ-, and θ-aluminas was identified by using selected-area electron diffraction. Modifications that resulted from the

  5. EFFECTIVE ELASTIC PROPERTIES OF ALUMINA-ZIRCONIA COMPOSITE CERAMICS - PART 4. TENSILE MODULUS OF POROUS ALUMINA AND ZIRCONIA

    Directory of Open Access Journals (Sweden)

    W. Pabst

    2004-12-01

    Full Text Available In this fourth paper of a series on the effective elastic properties of alumina-zirconia composite ceramics the influence of porosity on the effective tensile modulus of alumina and zirconia ceramics is discussed. The examples investigated are alumina and zirconia ceramics prepared from submicron powders by starch consolidation casting using two different types of starch, potato starch (median size D50 =47.2 µm and corn starch (median size D50 =13.7 µm. The dependence of effective tensile moduli E, on the porosity f, measured for porosities in the ranges of approx. 19-55 vol.% and 10-42 vol.% for alumina and zirconia, respectively, using a resonant frequency technique, was evaluated by fitting with various model relations, including newly developed ones. A detailed comparison of the fitting results suggests the superiority of the new relation E/E0 = (1 - f·(1 - f/fC, developed by the authors (with the tensile modulus of the dense ceramic material E0 and the critical porosity fC, over most other existing fit models. Only for special purposes and well-behaved data sets the recently proposed exponential relation E/E0 = exp [-Bf/(1 - f] and the well-known Phani-Niyogi relation E/E0 = (1 - f/fCN might be preferable.

  6. Aluminum matrix composites reinforced with alumina nanoparticles

    CERN Document Server

    Casati, Riccardo

    2016-01-01

    This book describes the latest efforts to develop aluminum nanocomposites with enhanced damping and mechanical properties and good workability. The nanocomposites exhibited high strength, improved damping behavior and good ductility, making them suitable for use as wires. Since the production of metal matrix nanocomposites by conventional melting processes is considered extremely problematic (because of the poor wettability of the nanoparticles), different powder metallurgy routes were investigated, including high-energy ball milling and unconventional compaction methods. Special attention was paid to the structural characterization at the micro- and nanoscale, as uniform nanoparticle dispersion in metal matrix is of prime importance. The aluminum nanocomposites displayed an ultrafine microstructure reinforced with alumina nanoparticles produced in situ or added ex situ. The physical, mechanical and functional characteristics of the materials produced were evaluated using different mechanical tests and micros...

  7. Trends in metallo-organic chemistry of scandium, yttrium, and the lanthanides

    International Nuclear Information System (INIS)

    Singh, A.

    1994-01-01

    Several interesting aspects of the metallo-organic chemistry of group 3 and the lanthanides have been highlighted, which include: (a) the chemistry of a few notable organolanthanide compounds, alkoxo and aryloxo derivatives derived from sterically demanding ligands, (b) new trends in the chemistry of lanthanide heterometallic alkoxides, (c) an account of zero valent organometallics of yttrium and the lanthanides, and (d) aspects of agostic interactions in the lanthanide metallo-organic compounds. (author). 49 refs

  8. A study of the dynamics of hydrogen in yttrium using inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bennington, S M; Benham, M J; Ross, D K [Birmingham Univ. (UK). School of Physics and Space Research; Taylor, A D; Bowden, Z A [Rutherford Appleton Lab., Chilton (UK)

    1989-01-01

    The results of several high resolution inelastic scattering experiments on {alpha}-phase yttrium-hydrogen are presented including measurements of energy levels up to the fourth and a study of the splitting of certain states due to hydrogen-hydrogen interactions. An attempt is made to model the energy levels by using perturbed simple harmonic oscillator wavefunctions. This can account for most of the major features of the spectrum. (orig.).

  9. Extraction of nitrates of lanthanoids (3) of the yttrium group and yttrium (3) by trialkylbenzylammonium nitrate in toluene

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kovalev, S.V.; Keskinov, V.A.; Kopyrin, A.A.

    1997-01-01

    A study was made on extraction of nitrates of lanthanoids (3) of the yttrium group (terbium-lutetium) and yttrium (3) by trialkylbensylammonium nitrate in toluene at T=298.15 K pH 2. Extraction isotherms are described with account of formation of compound of (R 4 N) 2 [Ln(NO 3 ) 5 ] composition in organic phase. Values of extraction constants decreasing in terbium (3)-lutetium (3) series, were calculated. Value of extraction constant for yttrium (3) is close to the value of extraction constant for ytterbium (3). 13 refs., 2 figs., 3 tabs

  10. Thermoanalytical study of the decomposition of yttrium trifluoroacetate thin films

    International Nuclear Information System (INIS)

    Eloussifi, H.; Farjas, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.; Dammak, M.

    2013-01-01

    We present the use of the thermal analysis techniques to study yttrium trifluoroacetate thin films decomposition. In situ analysis was done by means of thermogravimetry, differential thermal analysis, and evolved gas analysis. Solid residues at different stages and the final product have been characterized by X-ray diffraction and scanning electron microscopy. The thermal decomposition of yttrium trifluoroacetate thin films results in the formation of yttria and presents the same succession of intermediates than powder's decomposition, however, yttria and all intermediates but YF 3 appear at significantly lower temperatures. We also observe a dependence on the water partial pressure that was not observed in the decomposition of yttrium trifluoroacetate powders. Finally, a dependence on the substrate chemical composition is discerned. - Highlights: • Thermal decomposition of yttrium trifluoroacetate films. • Very different behavior of films with respect to powders. • Decomposition is enhanced in films. • Application of thermal analysis to chemical solution deposition synthesis of films

  11. Yttrium Nitrate mediated Nitration of Phenols at room temperature in ...

    Indian Academy of Sciences (India)

    The described method is selective for phenols. ... the significant cause of post translational modification that can ... decades, significant attention was paid on nitration of phenols to .... Progress of the reaction can be noted visually. Yttrium.

  12. Synthesis and characterization of mesoporous ceria/alumina nanocomposite materials via mixing of the corresponding ceria and alumina gel precursors.

    Science.gov (United States)

    Khalil, Kamal M S

    2007-03-01

    Mesoporous ceria/alumina, CeO(2)/Al(2)O(3), composites containing 10, 20 and 30% (w/w) ceria were prepared by a novel gel mixing method. In the method, ceria gel (formed via hydrolysis of ammonium cerium(IV) nitrate by aqueous ammonium carbonate solution) and alumina gel (formed via controlled hydrolysis of aluminum tri-isopropoxide) were mixed together. The mixed gel was subjected to subsequent drying and calcination for 3 h at 400, 600, 800 and 1000 degrees C. The uncalcined (dried at 110 degrees C) and the calcined composites were investigated by different techniques including TGA, DSC, FTIR, XRD, SEM and nitrogen adsorption/desorption isotherms. Results indicated that composites calcined for 3 h at 800 degrees C mainly kept amorphous alumina structure and gamma-alumina formed only upon calcinations at 1000 degrees C. On the other hand, CeO(2) was found to crystallize in the common ceria, cerinite, phase and it kept this structure over the entire calcination range (400-1000 degrees C). Therefore, high surface areas, stable surface textures, and non-aggregated nano-sized ceria dispersions were obtained. A systematic texture change based on ceria ratio was observed, however in all cases mesoporous composite materials exposing thermally stable texture and structure were obtained. The presented method produces composite ceria/alumina materials that suit different applications in the field of catalysis and membranes technology, and throw some light on physicochemical factors that determine textural morphology and thermal stability of such important composite.

  13. Attempts at treating rheumatoid arthritis with radioactive yttrium

    International Nuclear Information System (INIS)

    Scott, J.T.

    1979-01-01

    Two years' observations on 33 knee joints in 33 patients with rheumatoid arthritis did not prove a therapeutic effect of Y 90 , which was tested in a randomized study against non-radioactive yttrium. It was noticable that 9 knee joints of the isotope group but only one of the control group became unstable. Independent of the yttrium treatment, significant improvement was noticed in patients where fibrin clots had been washed out of the joints in the course of arthroscopies. (orig.) [de

  14. Treatment of rheumatoid arthritis with 90yttrium. Follow up studies

    International Nuclear Information System (INIS)

    Teuber, J.; Baenkler, H.W.; Regler, G.; Erlangen-Nuernberg Univ., Erlangen

    1978-01-01

    90 Yttrium-silicate was injected into 131 knee-joints from patients with rheumatoid arthritis with stadium II-IV according to Steinbrocker. The observation period lasted until two years. After three months about 80% and after 24 months still more than 50% of the patients treated showed complete or partial remission. Side-effects as formerly observed with 198 -goldpreparations did not occur. Therefore the treatment with 90 Yttrium-silicate offers an alternative to surgical synovectomy. (orig.) [de

  15. Thermal decomposition of yttrium(III) propionate and butyrate

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2013-01-01

    The thermal decompositions of yttrium(III) propionate monohydrate (Y(C2H5CO2)3·H2O) and yttrium(III) butyrate dihydrate (Y(C3H7CO2)3·2H2O) were studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage microscopy. These two...

  16. Synthesis and reactivity of bis(tetramethylcyclopentadienyl) yttrium metallocenes including the reduction of Me(3)SiN(3) to [(Me(3)Si)(2)N](-) with [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)).

    Science.gov (United States)

    Lorenz, Sara E; Schmiege, Benjamin M; Lee, David S; Ziller, Joseph W; Evans, William J

    2010-07-19

    The metallocene precursors needed to provide the tetramethylcyclopentadienyl yttrium complexes (C(5)Me(4)H)(3)Y, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), and [(C(5)Me(4)H)(2)Y(mu-H)](2) for reactivity studies have been synthesized and fully characterized, and their reaction chemistry has led to an unexpected conversion of an azide to an amide. (C(5)Me(4)H)(2)Y(mu-Cl)(2)K(THF)(x), 1, synthesized from YCl(3) and KC(5)Me(4)H reacts with allylmagnesium chloride to make (C(5)Me(4)H)(2)Y(eta(3)-C(3)H(5)), 2, which is converted to [(C(5)Me(4)H)(2)Y][(mu-Ph)(2)BPh(2)], 3, with [Et(3)NH][BPh(4)]. Complex 3 reacts with KC(5)Me(4)H to form (C(5)Me(4)H)(3)Y, 4. The reduced dinitrogen complex, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-N(2)), 5, can be synthesized from either [(C(5)Me(4)H)(2)Y](2)[(mu-Ph)(2)BPh(2)], 3, or (C(5)Me(4)H)(3)Y, 4, with potassium graphite under a dinitrogen atmosphere. The (15)N labeled analogue, [(C(5)Me(4)H)(2)Y(THF)](2)(mu-eta(2):eta(2)-(15)N(2)), 5-(15)N, has also been prepared, and the (15)N NMR data have been compared to previously characterized reduced dinitrogen complexes. Complex 2 reacts with H(2) to form the corresponding hydride, [(C(5)Me(4)H)(2)Y(mu-H)](2), 6. Complex 5 displays similar reactivity to that of the analogous [(C(5)Me(4)H)(2)Ln(THF)](2)(mu-eta(2):eta(2)-N(2)) complexes (Ln = La, Lu), with substrates such as phenazine, anthracene, and CO(2). In addition, 5 reduces Me(3)SiN(3) to form (C(5)Me(4)H)(2)Y[N(SiMe(3))(2)], 7.

  17. Plasma-sprayed tantalum/alumina cermets

    International Nuclear Information System (INIS)

    Kramer, C.M.

    1977-12-01

    Cermets of tantalum and alumina were fabricated by plasma spraying, with the amount of alumina varied from 0 to 65 percent (by volume). Each of four compositions was then measured for tensile strength, elastic modulus, and coefficient of thermal expansion. In general, strength and strain to failure decreased with increasing alumina content: 62 MPa for 100 percent Ta to 19 MPa for 35 v percent Ta. A maximum of 0.1 percent strain was observed for the sprayed 100 percent Ta specimens. The coefficient of thermal expansion measured for the pure Ta was 6.2 (10 -6 )/K

  18. Mullite-alumina functionally gradient ceramics

    International Nuclear Information System (INIS)

    Pena, P.; Bartolome, J.; Requena, J.; Moya, J.S.

    1993-01-01

    Cracks free mullite-alumina Functionally Gradient Ceramics (FGC) have been obtained by sequential slip casting of Mullite-alumina slurries with different mullite/alumina ratios. These slurries were prepared with 65 % solids content and viscosities ranging from 10 to 40 mPa.s. The presence of cracks perpendicular to the FGC layers have been attributed to residual stresses developed because of the mismatch in thermal expansion between layers. The microstructure of the different layers, and de residual stress value σ R in each layer was also determined. (orig.)

  19. Efective infrared reflectivity and dielectric function of polycrystalline alumina ceramics

    Czech Academy of Sciences Publication Activity Database

    Nuzhnyy, Dmitry; Petzelt, Jan; Borodavka, Fedir; Vaněk, Přemysl; Šimek, Daniel; Trunec, D.; Maca, K.

    2017-01-01

    Roč. 254, č. 5 (2017), s. 1-8, č. článku 1600607. ISSN 0370-1972 R&D Projects: GA ČR GA15-08389S Institutional support: RVO:68378271 Keywords : alumina * ceramics * effective dielectric function * effective medium approximation * geometrical resonances * infrared reflectivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.674, year: 2016

  20. Study of the molybdenum retention in alumina

    International Nuclear Information System (INIS)

    Wilkinson, Maria V.; Mondino, Angel V.; Manzini, Alberto

    2002-01-01

    The Argentine National Atomic Energy Commission routinely produces 99 Mo by fission of highly enriched uranium contained in targets irradiated in RA-3 reactor. The current process begins with the dissolution of the irradiated target in a basic media, considering the possibility of changing the targets, it could be convenient to dissolve them in acid media. The use of alumina as a first separation step in acid dissolution processes is already known although it is necessary to determine both the type of alumina to be used and the separation conditions. The study of molybdenum retention in alumina was performed at laboratory scale, using Mo-99 as radiotracer. Different kinds of alumina were tried, varying charge solution acidity. Influence of uranium concentration in the loading solution on molybdenum retention was also studied. (author)

  1. Sintering behaviour of spinel–alumina composites

    Indian Academy of Sciences (India)

    Administrator

    College of Engineering & Ceramic Technology, Kolkata 700 010, India. †. School of .... Chemical compositions of different batches of spinel–alumina composites. Chemistry ..... sence of magnesio–aluminate spinel, Ph D Thesis, University.

  2. Control of porosity in alumina for catalytic purposes - a review; Controle de porosidade em aluminas para fins cataliticos - uma revisao

    Energy Technology Data Exchange (ETDEWEB)

    Moure, Gustavo Torres [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Hidrorrefino, Lubrificantes e Parafinas; Morgado Junior, Edisson [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Setor de Tecnologia de Craqueamento Catalitico; Figueiredo, Cecilia Maria C.

    1999-12-01

    In recent years, the Alumina Group, of the Catalysts Division of CENPES, has dedicated research to develop and characterize alumina for the catalytic processes of interest to PETROBRAS. Control of the texture of the alumina and, consequently, the alumina based catalysts, is crucially important to their adequacy and performance. Knowledge of the porosity formation mechanisms in alumina was fundamental for the development of catalysts to satisfy the demand from PETROBRAS. This comprises the scope of this review. (author)

  3. Mechanical properties of lanthanum and yttrium chromites

    Energy Technology Data Exchange (ETDEWEB)

    Paulik, S.W.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    In an operating high-temperature (1000{degrees}C) solid oxide fuel cell (SOFC), the interconnect separates the fuel (P(O{sub 2}){approx}10{sup -16} atm) and the oxidant (P(O2){approx}10{sup 0.2} atm), while being electrically conductive and connecting the cells in series. Such severe atmospheric and thermal demands greatly reduce the number of viable candidate materials. Only two materials, acceptor substituted lanthanum chromite and yttrium chromite, meet these severe requirements. In acceptor substituted chromites (Sr{sup 2+} or Ca{sup 2+} for La{sup 3+}), charge compensation is primarily electronic in oxidizing conditions (through the formation of Cr{sup 4+}). Under reducing conditions, ionic charge compensation becomes significant as the lattice becomes oxygen deficient. The formation of oxygen vacancies is accompanied by the reduction of Cr{sup 4+} ions to Cr{sup 3+} and a resultant lattice expansion. The lattice expansion observed in large chemical potential gradients is not desirable and has been found to result in greatly reduced mechanical strength.

  4. Neutron scattering study of yttrium iron garnet

    Science.gov (United States)

    Shamoto, Shin-ichi; Ito, Takashi U.; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato; Akatsu, Mitsuhiro; Kodama, Katsuaki; Nakao, Akiko; Moyoshi, Taketo; Munakata, Koji; Ohhara, Takashi; Nakamura, Mitsutaka; Ohira-Kawamura, Seiko; Nemoto, Yuichi; Shibata, Kaoru

    2018-02-01

    The nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y3Fe5O12 have been studied using neutron scattering. The refined nuclear structure is distorted to a trigonal space group of R 3 ¯ . The highest-energy dispersion extends up to 86 meV. The observed dispersions are reproduced by a simple model with three nearest-neighbor-exchange integrals between 16 a (octahedral) and 24 d (tetrahedral) sites, Ja a, Ja d, and Jd d, which are estimated to be 0.00 ±0.05 , -2.90 ±0.07 , and -0.35 ±0.08 meV, respectively. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of q -integrated dynamical spin susceptibility χ″(E ) exhibits a square-root energy dependence at low energies. The magnon density of state is estimated from χ″(E ) obtained on an absolute scale. The value is consistent with the single chirality mode for the magnon branch expected theoretically.

  5. Results of recent KROTOS FCI tests. Alumina vs. corium melts

    Energy Technology Data Exchange (ETDEWEB)

    Huhtiniemi, I.; Magallon, D.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    Recent results from KROTOS fuel-coolant interaction experiments are discussed. Five tests with alumina were performed under highly subcooled conditions, all of these tests resulted in spontaneous steam explosions. Additionally, four tests were performed at low subcooling to confirm, on one hand, the suppression of spontaneous steam explosions under such conditions and, on the other hand, that such a system is still triggerable using an external initiator. The other test parameters in these alumina tests included the melt superheat and the initial pressure. All the tests in the investigated superheat range (150 K - 750 K) produced a steam explosion and no evidence of the explosion suppression by the elevated initial pressure (in the limited range of 0.1 - 0.375 MPa) was observed in the alumina tests. The corium test series include a test with 3 kg of melt under both subcooled and near saturated conditions at ambient pressure. Two additional tests were performed with subcooled water; one test was performed at an elevated pressure of 0.2 MPa with 2.4 kg of melt and another test with 5.1 kg of melt at ambient pressure. None of these tests with corium produced a propagating energetic steam explosion. However, propagating low energy (about twice the energy of the trigger pulse) events were observed. All corium tests produced significantly higher water level swells during the mixing phase than the corresponding alumina tests. Present experimental evidence suggests that the water depletion in the mixing zone suppresses energetic steam explosions with corium melts at ambient pressure and in the present pour geometry. Processes that could produce such a difference in void generation are discussed. (author)

  6. Yttrium implantation effects on extra low carbon steel and pure iron

    Energy Technology Data Exchange (ETDEWEB)

    Caudron, E.; Buscail, H. [Clermont-Ferrand-2 Univ., Le Puy en Velay (France). Lab. Vellave d`Elaboration; Jacob, Y.P.; Stroosnijder, M.F. [Institute for Advanced Materials, Joint Research Center, The European Commission, 21020, Ispra (Vatican City State, Holy See) (Italy); Josse-Courty, C. [Laboratoire de Recherche sur la Reactivite des Solides, UMR 56-13 CNRS, UFR Sciences et Techniques, 9 Avenue A. Savary, B.P. 400, 21011, Dijon Cedex (France)

    1999-05-25

    Extra low carbon steel and pure electrolytic iron samples were yttrium implanted using ion implantation technique. Compositions and structures of pure iron and steel samples were investigated before and after yttrium implantation by several analytical and structural techniques (RBS, SIMS, RHEED and XRD) to observe the yttrium implantation depth profiles in the samples. This paper shows the different effects of yttrium implantations (compositions and structures) according to the implanted sample nature. (orig.) 23 refs.

  7. Effect of hydrothermal process for inorganic alumina sol on crystal structure of alumina gel

    Directory of Open Access Journals (Sweden)

    K. Yamamura

    2016-09-01

    Full Text Available This paper reports the effect of a hydrothermal process for alumina sol on the crystal structure of alumina gel derived from hydrothermally treated alumina sol to help push forward the development of low temperature synthesis of α-Al2O3. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in the production of a transparent alumina sol. The alumina sol was treated with a hydrothermal process and transformed into an alumina gel film by drying at room temperature. Crystallization of the alumina gel to α-Al2O3 with 900 °C annealing was dominant for a hydrothermal temperature of 100 °C and a hydrothermal time of 60 min, as production of diaspore-like species was promoted with the hydrothermal temperature and time. Excess treatments with hydrothermal processes at higher hydrothermal temperature for longer hydrothermal time prevented the alumina gel from being crystallized to α-Al2O3 because the excess hydrothermal treatments promoted production of boehmite.

  8. Yttrium 90 microspheres for the treatment of hepatocellular carcinoma.

    Science.gov (United States)

    Memon, Khairuddin; Lewandowski, Robert J; Riaz, Ahsun; Salem, Riad

    2013-01-01

    Yttrium-90 microspheres are radioactive particles which are increasingly being employed for treating patients with unresectable hepatocellular carcinoma (HCC). The procedure is called radioembolization. It involves the injection of micron-sized embolic particles loaded with a radioisotope by use of transarterial techniques. Because of the sensitivity of liver parenchyma and relative insensitivity of tumor, external radiation has played a limited role in treating HCC. (90)Y administered via arterial route directs the highly concentrated radiation to the tumor while healthy liver parenchyma is relatively spared due to its preferential blood supply from portal venous blood. This technique has proven useful for the majority of patients with HCC as most of them present in advanced stage, beyond potentially curative options (resection/liver transplantation). (90)Y microspheres can be used in downstaging large tumors to bring within transplantable criteria, in patients with portal venous thrombosis due to tumor invasion and as palliative therapy. There are two available devices for (90)Y administration; TheraSphere® (glass based) and SIR-Spheres® (resin based). The procedure is performed on an outpatient basis. The incidence of complications is comparatively less and may include nausea, fatigue, abdominal pain, hepatic dysfunction, biliary injury, fibrosis, radiation pneumonitis, GI ulcers, and vascular injury; however, these can be avoided by meticulous pretreatment assessment, careful patient selection, and adequate dosimetry. This article explores the technical and clinical aspects of (90)Y radioembolization with keeping emphasis on patient selection, uses, and complications.

  9. Shock diffraction in alumina powder

    International Nuclear Information System (INIS)

    Venz, G.; Killen, P.D.; Page, N.W.

    1996-01-01

    In order to produce complex shaped components by dynamic compaction of ceramic powders detailed knowledge of their response under shock loading conditions is required. This work attempts to provide data on release effects and shock attenuation in 1 μm and 5 μm α-alumina powders which were compacted to between 85 % and 95 % of the solid phase density by the impact of high velocity steel projectiles. As in previous work, the powder was loaded into large cylindrical dies with horizontal marker layers of a contrasting coloured powder to provide a record of powder displacement in the recovered specimens. After recovery and infiltration with a thermosetting resin the specimens were sectioned and polished to reveal the structure formed by the passage of the projectile and shock wave. Results indicate that the shock pressures generated were of the order of 0.5 to 1.4 GPa and higher, with shock velocities and sound speeds in the ranges 650 to 800 m/s and 350 to 400 m/s respectively

  10. Studies on yttrium oxide coatings for corrosion protection against molten uranium

    International Nuclear Information System (INIS)

    Chakravarthy, Y.; Bhandari, Subhankar; Pragatheeswaran; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Kumar, Jay; Kutty, T.R.G.

    2012-01-01

    Yttrium oxide is resistant to corrosion by molten uranium and its alloys. Yttrium oxide is recommended as a protective oxide layer on graphite and metal components used for melting and processing uranium and its alloys. This paper presents studies on the efficacy of plasma sprayed yttrium oxide coatings for barrier applications against molten uranium

  11. The influence of annealing on yttrium oxide thin film deposited by reactive magnetron sputtering: Process and microstructure

    Directory of Open Access Journals (Sweden)

    Y. Mao

    2017-01-01

    Full Text Available Yttrium oxide thin films were prepared by reactive magnetron sputtering in different deposition condition with various oxygen flow rates. The annealing influence on the yttrium oxide film microstructure is investigated. The oxygen flow shows a hysteresis behavior on the deposition rate. With a low oxygen flow rate, the so called metallic mode process with a high deposition rate (up to 1.4µm/h was achieved, while with a high oxygen flow rate, the process was considered to be in the poisoned mode with an extremely low deposition rate (around 20nm/h. X-ray diffraction (XRD results show that the yttrium oxide films that were produced in the metallic mode represent a mixture of different crystal structures including the metastable monoclinic phase and the stable cubic phase, while the poisoned mode products show a dominating monoclinic phase. The thin films prepared in metallic mode have relatively dense structures with less porosity. Annealing at 600 °C for 15h, as a structure stabilizing process, caused a phase transformation that changes the metastable monoclinic phase to stable cubic phase for both poisoned mode and metallic mode. The composition of yttrium oxide thin films changed from nonstoichiometric to stoichiometric together with a lattice parameter variation during annealing process. For the metallic mode deposition however, cracks were formed due to the thermal expansion coefficient difference between thin film and the substrate material which was not seen in poisoned mode deposition. The yttrium oxide thin films that deposited in different modes give various application options as a nuclear material.

  12. Decision tree analysis to assess the cost-effectiveness of yttrium microspheres for treatment of hepatic metastases from colorectal cancer

    International Nuclear Information System (INIS)

    Kelley, B.B.; Walker, G.D.; Miles, K.A.

    2002-01-01

    Full text: The aim is to determine the cost-effectiveness of yttrium microsphere treatment of hepatic metastases from colorectal cancer, with and without FDG-PET for detection of extra-hepatic disease. A decision tree was created comparing two strategies for yttrium treatment with chemotherapy, one incorporating PET in addition to CT in the pre-treatment work-up, to a strategy of chemotherapy alone. The sensitivity and specificity of PET and CT were obtained from the Federal Government PET review. Imaging costs were obtained from the Medicare benefits schedule with an additional capital component added for PET (final cost $1200). The cost of yttrium treatment was determined by patient-tracking. Previously published reports indicated a mean gain in life-expectancy from treatment of 0.52 years. Patients with extra-hepatic metastases were assumed to receive no survival benefit. Cost effectiveness was expressed as incremental cost per life-year gained (ICER). Sensitivity analysis determined the effect of prior probability of extra-hepatic disease on cost-savings and cost-effectiveness. The cost of yttrium treatment including angiography, particle perfusion studies and bed-stays, was $10530. A baseline value for prior probability of extra-hepatic disease of 0.35 gave ICERs of $26,378 and $25,271 for the no-PET and PET strategies respectively. The PET strategy was less expensive if the prior probability of extra-hepatic metastases was greater than 0.16 and more cost-effective if above 0.28. Yttrium microsphere treatment is less cost-effective than other interventions for colon cancer but comparable to other accepted health interventions. Incorporating PET into the pre-treatment assessment is likely to save costs and improve cost-effectiveness. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  13. Pressure of saturated vapor of yttrium and zirconium acetylacetonates

    Energy Technology Data Exchange (ETDEWEB)

    Trembovetskij, G.V.; Berdonosov, S.S.; Murav' eva, I.A.; Martynenko, L.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1984-08-01

    The static method and the flow method using /sup 91/Y and /sup 95/Zr radioactive indicators have been applied to determine pressure of saturated vapour of yttrium and zirconium acetylacetonates. Values of thermodynamic functions ..delta..Hsub(subl)=(98+-16)kJ/mol and ..delta..Ssub(subl.)=(155+-30)J/mol x K are calculated for sublimation of yttrium acetylacetonate. For sublimation of zirconium acetylacetonates ..delta..Hsub(subl) equals (116+-38) kJ/mol and ..delta..Ssub(subl) is equal to (198+-65) J/molxK.

  14. Determination of copper oxidizing power in superconducting yttrium ceramics

    International Nuclear Information System (INIS)

    Pontaler, R.P.; Lebed', N.B.

    1989-01-01

    A new photometric method for determining the formal copper degree of oxidation and oxygen deficiency in superconducting high-temperature oxides containing yttrium, barium and copper is developed. The method is based on oxidation of Co(2) complex with EDTA by Cu(3) ions in acetrate buffer solution with pH 4.2-4.7 and allows one to determine 1-10% of Cu(3). Relative standard deviation when determining Cu(3) makes up 0.03-0.05. Using a qualitative reaction with the application of sodium vanadate hydrochloride solution the absence of peroxide compound in superconducting yttrium ceramics is ascertained

  15. Effect of Alumina Addition to Zirconia Nano-composite on Low Temperature Degradation Process and Biaxial Strength

    Directory of Open Access Journals (Sweden)

    Moluk Aivazi

    2016-12-01

    Full Text Available Ceramic dental materials have been considered as alternatives to metals for dental implants application. In this respect, zirconia tetragonal stabilized with %3 yttrium, is of great importance among the ceramic materials for endosseous dental implant application. Because of its good mechanical properties and color similar to tooth. The aim and novelty of this study was to design and prepare Y-TZP nano-composite to reduce the degradation process at low temperature by alumina addition and maintaining submicron grain sized. Also, flexural strength of nano-composite samples was evaluated. Toward this purpose, alumina-Y-TZP nano-composites containing 0–30 vol% alumina (denoted as A-Y-TZP 0-30 were fabricated using α-alumina and Y-TZP nano-sized by sintering pressure less method. The synthesized samples were characterized using x-ray diffraction, field emission scanning electron microscopy equipped with energy dispersive x-ray spectroscopy techniques. Nano-composite samples with high density (≥96% and grain sized of ≤ 400 nm was obtained by sintering at 1270 °C for 170 min. After low temperature degradation test (LTD, A-Y-TZP20 and A-Y-TZP30 not showed monoclinic phase and the flexural strength in all of samples were higher than A-Y-TZP0. It was concluded that the grains were remained in submicron sized and A-Y-TZP20 and A-Y-TZP30 did not present biaxial strength reduction after LTD test.

  16. High contrast laser marking of alumina

    International Nuclear Information System (INIS)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-01-01

    Highlights: • Laser marking of alumina using near infrared (NIR) lasers was experimentally analyzed. • Color change produced by NIR lasers is due to thermally induced oxygen vacancies. • Laser marking results obtained using NIR lasers and green laser are compared. • High contrast marks on alumina were achieved. - Abstract: Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks

  17. Surface modifications induced by yttrium implantation on low manganese-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Caudron, E.; Buscail, H. [Univ. Blaise Pascal Clermont-Fd II, Le Puy en Velay (France). Lab. Vellave d' Elaboration et d' Etude des Materiaux; Haanapel, V.A.C.; Jacob, Y.P.; Stroosnijder, M.F. [Institute for Health and Consumer Protection, Joint Research Center, The European Commission, 21020, Ispra (Italy)

    1999-12-15

    Low manganese-carbon steel samples were ion implanted with yttrium. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in the sample. Yttrium implantation effects were characterized using several analytical and structural techniques such as X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction, glancing angle X-ray diffraction and Rutherford backscattering spectrometry. In this paper it is shown that correlation between composition and structural analyses provides an understanding of the main compounds induced by yttrium implantation in low manganese-carbon steel. (orig.)

  18. Severe wear behaviour of alumina balls sliding against diamond ...

    Indian Academy of Sciences (India)

    study, alumina ball was chosen as the counter body material to show better performance of the ... Tribology is a relatively new science that considers ... The science is applied in ... for example, in hip prosthesis, instead of existing alumina.

  19. Challenges and Strategies in the Synthesis of Mesoporous Alumina Powders and Hierarchical Alumina Monoliths

    Directory of Open Access Journals (Sweden)

    Anne Galarneau

    2012-02-01

    Full Text Available A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous γ-Al2O3 is presented. The resulting mesoporous alumina materials feature high surface areas (400 m2 g−1, large pore volumes (0.8 mL g−1 and the ��-Al2O3 phase is obtained at low temperature (500 °C. The main advantages and drawbacks of different preparations of mesoporous alumina materials exhibiting high specific surface areas and large pore volumes such as surfactant-nanostructured alumina, sol-gel methods and hierarchically macro-/mesoporous alumina monoliths have been analyzed and compared. The most reproducible synthesis of mesoporous alumina are given. Evaporation-Induced Self-Assembly (EISA is the sole method to lead to nanostructured mesoporous alumina by direct templating, but it is a difficult method to scale-up. Alumina featuring macro- and mesoporosity in monolithic shape is a very promising material for in flow applications; an optimized synthesis is described.

  20. Treatment of persistent knee synovitis with Yttrium 90

    International Nuclear Information System (INIS)

    Bouyoucef, S.E.

    2007-01-01

    Full text: Management of persistent knee synovitis includes both systemic and local articular treatment relevant to specific etiology. Local treatment may involve attempts to control inflammation and pain in knee joints by intra articular application of analgesics or glucocorticoids. However, in many patients these fail to reduce significantly the synovitis phenomenon and moreover they may lead to severe side effects. Radiosynoviorthesis with Y90 has been in use for many years in several joint pathologies. Indications of Radiosynoviorthesis include various inflammatory and degenerative diseases and its use should be envisaged when other conservative methods have failed like intra articular injections of long acting corticosteroids. Persistent knee synovitis is defined by the presence of hydrops in the joint or functional impairment with warmth, pain and local signs and symptoms requiring intra articular injection of glucocorticoids. In this study, 151 knees with persistent knee synovitis have been treated with Y 90 and have had all a minimum of one year follow up. Many parameters have been identified to measure efficiency of the RSO including pain, hydarthrosis, mobility, as well as global perception of the patients. Excellent and good responses have been appreciated through pain at rest, pain at stress, volume of effusion, and articular mobility. Results showed that percentage of excellent and good response is superior to 80% at three and six months. Success of Y 90 appears to be higher for rheumatoid arthritis as well as for oligoarthritis. Whatever the etiology, intensity of the inflammatory process appears one the major parameters which could better predict the outcomes of yttrium 90 in persistent knee synovitis. (author)

  1. Electrochemically produced alumina as TL detector

    International Nuclear Information System (INIS)

    Osvay, M.

    1996-01-01

    The goal of this work was to compare the TL properties of various electrochemically produced alumina layers (E-AIO) in order to investigate the effect of the electrolyte and the Mg content on the alloys. It has been found that the TL sensitivity of oxidised layers is more influenced by the type of electrolyte, than by the composition of alloy. Hard oxide layer evolved in reduction electrolyte has rather different character compared to other alumina production investigated. The effect of reducing media seems to be very important during preparation of alumina layer. One of the advantages properties of E-AIO is, that it serve a promising method to increase the measuring range of TL method above 10 kGy as well. (author)

  2. Iron films deposited on porous alumina substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yasuhiro, E-mail: yyasu@rs.kagu.tus.ac.jp; Tanabe, Kenichi; Nishida, Naoki [Tokyo University of Science (Japan); Kobayashi, Yoshio [The University of Electro-Communications (Japan)

    2016-12-15

    Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 – 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.

  3. Hydrogen diffusion in Pb β''-alumina

    International Nuclear Information System (INIS)

    Bates, J.B.; Dudney, N.J.; Wang, J.C.

    1985-01-01

    The mobile Na + ions in Na β''-alumina can be completely exchanged with Pb 2+ ions by treatment in molten PbCl 2 . When this exchange was carried out in the presence of air, protons in the form of OH - were introduced into the conduction layers along with lead ions. Although the concentration of OH - was low, on the order of 5 x 10 -3 per formula unit of Pb/sub 0.84/Mg/sub 0.67/Al/sub 10.33/O_1_7, the distribution of OH - after ion exchange indicated that the proton mobility in Pb β''-alumina is high. The potential use of Pb β''-alumina as a fast proton conductor that is stable at 400 0 C motivated further studies of hydrogen diffusion. In this report, the results of tracer diffusion measurements by isotope exchange will be presented

  4. Pt/Au nanoalloy supported on alumina and chlorided alumina: DFT and experimental analysis

    Science.gov (United States)

    Sharifi, N.; Falamaki, C.; Ghorbanzadeh Ahangari, M.

    2018-04-01

    Density functional theory (DFT) was used to explore the adsorption of Pt/Au nanoalloy onto a pure and chlorided γ-Al2O3(110) surface, which has been applied in numerous catalytic reactions. First, we considered the adsorption properties of Pt clusters (n ≤ 5) onto the Al2O3(110) surface to determine the most stable Pt cluster on alumina surface in reforming processes. After full structural relaxations of Pt clusters at various configurations on alumina, our computed results expressed that the minimum binding energy (‑5.67 eV) is accrued for Pt4 cluster and the distance between the nearest Pt atom in the cluster to the alumina surface is equal to 1.13 Å. Then, we investigated the binding energies, geometries, and electronic properties of adsorbed Aun clusters (n ≤ 6) on the γ-Al2O3(110) surface. Our studied showed that Au5 was the most thermodynamically stable structure on γ-Al2O3. Finally, we inspected these properties for adsorbed Au clusters onto the Pt4-decorated alumina (Aun/Pt4-alumina) system. The binding energy of the Au4/Pt4-alumina system was ‑5.01 eV, and the distance between Au4 cluster and Pt4-alumina was 1.33 Å. The Au4/Pt4alumina system was found to be the most stable nanometer-sized catalyst design. At last, our first-principles calculations predicted that the best position of embedment Cl on the Au4/Pt4-alumina.

  5. Electron-irradiation-induced phase transformation in alumina

    International Nuclear Information System (INIS)

    Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

    2010-01-01

    In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

  6. Blocking of grain reorientation in self-doped alumina materials

    International Nuclear Information System (INIS)

    Suarez, M.; Fernandez, A.; Menendez, J.L.; Ramirez-Rico, J.; Torrecillas, R.

    2011-01-01

    Alumina nanoparticles 10-20 nm in diameter were nucleated on alumina particles, 150 nm average diameter, by a colloidal route followed by calcination. It is shown that after sintering, the final grain size is up to 20% smaller due to the addition of the alumina nanoparticles. Electron backscattered diffraction analysis shows that whereas a correlation in the relative crystalline orientations between neighbouring grains exists in the pure materials, the addition of alumina nanoparticles results in a random crystalline orientation.

  7. On the use of hydrogen peroxide as a masking agent for the determination of yttrium in uranium oxide - yttrium oxide mixture

    International Nuclear Information System (INIS)

    Rastogi, R.K.; Chaudhuri, N.K.; Rizvi, G.H.; Subramanian, M.S.

    1985-01-01

    The use of peroxide as a masking agent for uranium during the EDTA titration of yttrium in an yttrium-uranium mixture containing large amounts of uranium was investigated. High acetate ion concentration was necessary to keep the peroxy complex of uranium in solution during the titration. It was observed that uranium could be tolerated up to 500 mg in the determination of yttrium with 0.5 ml of 30% hydrogen peroxide in approx. 1M acetate medium. The precision and accuracy of the method based on 16 determinations of yttrium at 6-16 mg level in the presence of 300 mg uranium was found to be +-0.2%. (author)

  8. Treatment of diffuse large B-cell lymphoma of the liver with yttrium-90 microsphere embolization.

    Science.gov (United States)

    Fenske, Timothy S; Benjamin, Heather; Kroft, Steven H; Hohenwalter, Eric J; Rilling, William S

    2008-11-01

    A 41-year-old male with a 4-year history of chronic hepatitis C presented with a 1-month history of abdominal pain, fatigue, weight loss, and night sweats. Laboratory examinations, chest, abdomen, and pelvic CT scans, PET-CT scans, ultrasound-guided needle biopsies of liver lesions, bone-marrow biopsy, flow cytometry, and immunohistochemical staining for B-cell markers including CD20. Chemoresistant diffuse large B-cell lymphoma, with gradual loss of CD20 antigen expression. Embolization of hepatic tumors using yttrium-90 microspheres (Therasphere, Theragenics Corporation, Buford, GA).

  9. Studies of alumina additions in zirconia - magnesia

    International Nuclear Information System (INIS)

    Muccillo, R.

    1987-01-01

    Ionic conductivity measurements have been carried out in the 500 0 C - 1000 0 C temperature range in Mg - PSZ (Partially Stabilized Zirconia) with 0.5 to 10 mol % alumina additions. All specimens were prepared by pressing followed by pre - and sintering at 1000 0 C/2h and1450 0 C/4h, respectively. Thermal histerysis of the ionic conductivity have been detected, probably due to phase changes in the Mg-PSZ samples. The results show that alumina additions up to 2.1% enhances densification with no major variations in electrical resistivity values. (Author) [pt

  10. Tritium compatibility of alumina and Fosterite

    Energy Technology Data Exchange (ETDEWEB)

    Coffin, D.O.

    1979-09-01

    Many pressure measurements are required to control processing of the fuel gases associated with fusion power reactors. Since most pressure transducers respond to changes in pressure sensitive electrical parameters, insulators will be required to withstand chronic exposures to concentrated tritium. For this investigation samples of alumina and Fosterite were exposed to concentrated tritium gas for 11 weeks. Gas phase impurities were then analyzed for clues that would indicate decomposition of the exposed materials. The only gaseous impurity resulting from these tritium exposures was tritio-methane, which is always produced when tritium is stored in stainless steel containers. There was no evidence that either alumina or Fosterite decomposed in the presence of tritium.

  11. Delayed Failure in a Shock Loaded Alumina

    International Nuclear Information System (INIS)

    Cooper, G. A.; Millett, J. C. F.; Bourne, N. K.; Dandekar, D. P.

    2006-01-01

    Manganin stress gauges have been used to measure the lateral stress in a shock-loaded alumina. In combination with known longitudinal stresses, these have been used to determine the shear strength of this material, behind the shock front. The two-step nature of the lateral stress traces shows a slow moving front behind the main shock, behind which shear strength undergoes a significant decrease. Results also show that this front decreases markedly in velocity as the HEL is crossed, suggesting that limited plasticity occurs during inelastic deformation. Finally, comparison of measured shear strengths with other aluminas shows a high degree of agreement

  12. Fabrication of Ceramic Matrix Composite Tubes Using a Porous Mullite/Alumina Matrix and Alumina/Mullite Fiber

    National Research Council Canada - National Science Library

    Radsick, Timothy

    2001-01-01

    ... or from inadequate oxide-based ones. A porous mullite/alumina matrix combined with alumina/mullite fiber reinforcement eliminates the need for an interface coating while producing a strong, tough and oxidation resistant composite...

  13. High performance yttrium-doped BSCF hollow fibre membranes

    DEFF Research Database (Denmark)

    Haworth, P.; Smart, S.; Glasscock, Julie

    2012-01-01

    measurements in air was similar for both compositions, suggesting that the higher oxygen fluxes obtained for BSCFY hollow fibres could be attributed to the higher non-stoichiometry due to yttrium addition to the BSCF crystal structure. In addition, the improvement of oxygen fluxes for small wall thickness (∼0...

  14. Microstructure and defect chemistry of yttrium aluminium garnet ceramics

    International Nuclear Information System (INIS)

    Schuh, L.H.

    1989-01-01

    This thesis describes basic aspects concerning the defect chemistry and the microstructure of yttrium aluminium garnet ceramics. The work consists of three parts: a literature study, an experimental part and a section giving computer simulation data of defects. (author). 320 refs.; 68 figs.; 72 schemes; 32 tabs

  15. A thermal neutron scattering law for yttrium hydride

    Science.gov (United States)

    Zerkle, Michael; Holmes, Jesse

    2017-09-01

    Yttrium hydride (YH2) is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH2) and yttrium bound in yttrium hydride (Y-YH2) prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH2 are used to prepare H-YH2 and Y-YH2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β) function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.

  16. Structural and dielectric properties of yttrium substituted nickel ferrites

    International Nuclear Information System (INIS)

    Ognjanovic, Stevan M.; Tokic, Ivan; Cvejic, Zeljka; Rakic, Srdjan; Srdic, Vladimir V.

    2014-01-01

    Graphical abstract: - Highlights: • Dense NiFe 2−x Y x O 4 ceramics (with 0 ≤ x ≤ 0.3) were prepared. • Pure spinels were obtained for x ≤ 0.07 while for x ≥ 0.15 samples had secondary phases. • With addition of yttrium, ac conductivity slightly increased. • We suggest several effects that can explain the observed changes in ac conduction. • With addition of yttrium, dielectric constant increased while the tg δ decreased. - Abstract: The influence of Y 3+ ions on structural and dielectric properties of nickel ferrites (NiFe 2−x Y x O 4 , where 0 ≤ x ≤ 0.3) has been studied. The as-synthesized samples, prepared by the co-precipitation method, were analyzed by XRD and FTIR which suggested that Y 3+ ions were incorporated into the crystal lattice for all the samples. However, the XRD analysis of the sintered samples showed that secondary phases appear in the samples with x > 0.07. The samples have densities greater than 90% TD and the SEM images showed that the grain size decreases with the addition of yttrium. Dielectric properties measured from 150 to 25 °C in the frequency range of 100 Hz–1 MHz showed that the addition of yttrium slightly increases the ac conductivity and decreases the tg δ therefore making the materials better suited for the use in microwave devices

  17. Thermal decomposition of yttrium(III) hexanoate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Attique, Fahmida

    2015-01-01

    The thermal decomposition of yttrium(III) hexanoate (Y(C5H11CO2)3)·xH2O in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction at a laboratory Cu-tube source and in-situ experiments at a synchrotron radiation source as well as hot...

  18. Thermal decomposition of Yttrium(III) isovalerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2016-01-01

    The thermal behaviour of yttrium(III) isovalerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, FTIR-spectroscopy, hot-stage optical microscopy and X-ray diffraction with a laboratory Cu-tube source as well as with a synchrotron radiation source...

  19. Thermal decomposition of yttrium(III) valerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2014-01-01

    The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting...

  20. Polymorphism and electrical behaviour of yttrium thin films

    International Nuclear Information System (INIS)

    Kaul, U.K.; Srivastava, O.N.

    1978-01-01

    It appears that the thickness-resistivity behaviour of yttrium embodying a thickness-dependent polymorphic phase transition can be explained in terms of surface scattering by taking into account the effect of the change in phase. It is interesting to note that, as a result of the polymorphic transition, the resistivity-thickness curve has an unusual shape. (Auth.)

  1. A new f.c.c. phase in yttrium films

    International Nuclear Information System (INIS)

    Kaul, V.K.; Srivastava, O.N.

    1976-01-01

    A new polymorphic phase characterised by a face-centered cubic structure, with lattice parameter 5.83 +- 0.02A, has been identified in thin films of yttrium. Electron diffraction evidence and electrical resistivity measurements have been carried out in order to detect the new f.c.c. phase. (Auth.)

  2. Characterization of alumina using small angle neutron scattering (SANS)

    International Nuclear Information System (INIS)

    Megat Harun Al Rashidn Megat Ahmad; Abdul Aziz Mohamed; Azmi Ibrahim; Che Seman Mahmood; Edy Giri Rachman Putra; Muhammad Rawi Muhammad Zin; Razali Kassim; Rafhayudi Jamro

    2007-01-01

    Alumina powder was synthesized from an aluminium precursor and studied using small angle neutron scattering (SANS) technique and complemented with transmission electron microscope (TEM). XRD measurement confirmed that the alumina produced was high purity and highly crystalline αphase. SANS examination indicates the formation of mass fractals microstructures with fractal dimension of about 2.8 on the alumina powder. (Author)

  3. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white, odorless...

  4. Hanford isotope project strategic business analysis yttrium-90 (Y-90)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-01

    The purpose of this analysis is to address the short-term direction for the Hanford yttrium-90 (Y-90) project. Hanford is the sole DOE producer of Y-90, and is the largest repository for its source in this country. The production of Y-90 is part of the DOE Isotope Production and Distribution (IP and D) mission. The Y-90 is ``milked`` from strontium-90 (Sr-90), a byproduct of the previous Hanford missions. The use of Sr-90 to produce Y-90 could help reduce the amount of waste material processed and the related costs incurred by the clean-up mission, while providing medical and economic benefits. The cost of producing Y-90 is being subsidized by DOE-IP and D due to its use for research, and resultant low production level. It is possible that the sales of Y-90 could produce full cost recovery within two to three years, at two curies per week. Preliminary projections place the demand at between 20,000 and 50,000 curies per year within the next ten years, assuming FDA approval of one or more of the current therapies now in clinical trials. This level of production would incentivize private firms to commercialize the operation, and allow the government to recover some of its sunk costs. There are a number of potential barriers to the success of the Y-90 project, outside the control of the Hanford Site. The key issues include: efficacy, Food and Drug Administration (FDA) approval and medical community acceptance. There are at least three other sources for Y-90 available to the US users, but they appear to have limited resources to produce the isotope. Several companies have communicated interest in entering into agreements with Hanford for the processing and distribution of Y-90, including some of the major pharmaceutical firms in this country.

  5. Hanford isotope project strategic business analysis yttrium-90 (Y-90)

    International Nuclear Information System (INIS)

    1995-10-01

    The purpose of this analysis is to address the short-term direction for the Hanford yttrium-90 (Y-90) project. Hanford is the sole DOE producer of Y-90, and is the largest repository for its source in this country. The production of Y-90 is part of the DOE Isotope Production and Distribution (IP and D) mission. The Y-90 is ''milked'' from strontium-90 (Sr-90), a byproduct of the previous Hanford missions. The use of Sr-90 to produce Y-90 could help reduce the amount of waste material processed and the related costs incurred by the clean-up mission, while providing medical and economic benefits. The cost of producing Y-90 is being subsidized by DOE-IP and D due to its use for research, and resultant low production level. It is possible that the sales of Y-90 could produce full cost recovery within two to three years, at two curies per week. Preliminary projections place the demand at between 20,000 and 50,000 curies per year within the next ten years, assuming FDA approval of one or more of the current therapies now in clinical trials. This level of production would incentivize private firms to commercialize the operation, and allow the government to recover some of its sunk costs. There are a number of potential barriers to the success of the Y-90 project, outside the control of the Hanford Site. The key issues include: efficacy, Food and Drug Administration (FDA) approval and medical community acceptance. There are at least three other sources for Y-90 available to the US users, but they appear to have limited resources to produce the isotope. Several companies have communicated interest in entering into agreements with Hanford for the processing and distribution of Y-90, including some of the major pharmaceutical firms in this country

  6. Evidence of yttrium silicate inclusions in YSZ-porcelain veneers.

    Science.gov (United States)

    Stoner, Brian R; Griggs, Jason A; Neidigh, John; Piascik, Jeffrey R

    2014-04-01

    This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (X-ray (EDAX) was used for microstructural and elemental analysis. EDAX, for chemical analysis and transmission electron diffraction (TED) for structural analysis were both performed in the transmission electron microscope (TEM). Additionally, in order to spatially resolve Y-rich precipitates, micro-CT scans were conducted at varying depths within the porcelain veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ. © 2013 Wiley Periodicals, Inc.

  7. Yttrium-90 microspheres for the treatment of hepatocellular carcinoma.

    Science.gov (United States)

    Geschwind, Jean Francois H; Salem, Riad; Carr, Brian I; Soulen, Michael C; Thurston, Kenneth G; Goin, Kathleen A; Van Buskirk, Mark; Roberts, Carol A; Goin, James E

    2004-11-01

    Unresectable hepatocellular carcinoma is extremely difficult to treat. TheraSphere consists of yttrium-90 (a pure beta emitter) microspheres, which are injected into the hepatic arteries. This article reviews the safety and survival of patients with hepatocellular carcinoma who were treated with yttrium-90 microspheres. Eighty patients were selected from a database of 108 yttrium-90 microsphere-treated patients and were staged by using Child-Pugh, Okuda, and Cancer of the Liver Italian Program scoring systems. Patients were treated with local, regional, and whole-liver approaches. Survival from first treatment was analyzed with Kaplan-Meier and Cox regression methods. Adverse events and complications of treatment were coded by using the Southwest Oncology Group toxicity scoring system. Patients received liver doses ranging from 47 to 270 Gy. Thirty-two patients (40%) received more than 1 treatment. Survival correlated with pretreatment Cancer of the Liver Italian Program scores ( P = .002), as well as with the individual Cancer of the Liver Italian Program components, Child-Pugh class, alpha-fetoprotein levels, and percentage of tumor replacement. Patients classified as Okuda stage I (n = 54) and II (n = 26) had median survival durations and 1-year survival rates of 628 days and 63%, and 384 days and 51%, respectively ( P = .02). One patient died of liver failure judged as possibly related to treatment. Thus, in selected patients with hepatocellular carcinoma, yttrium-90 microsphere treatment is safe and well tolerated. On the basis of these results, a randomized controlled trial is warranted comparing yttrium-90 microsphere treatment with transarterial chemoembolization by using the Cancer of the Liver Italian Program system for prospective stratified randomization.

  8. Root Cause Analysis of Gastroduodenal Ulceration After Yttrium-90 Radioembolization

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Marnix G. E. H. [Stanford University School of Medicine, Division of Interventional Radiology (United States); Banerjee, Subhas [Stanford University School of Medicine, Division of Gastroenterology and Hepatology (United States); Louie, John D.; Abdelmaksoud, Mohamed H. K. [Stanford University School of Medicine, Division of Interventional Radiology (United States); Iagaru, Andrei H. [Stanford University School of Medicine, Division of Nuclear Medicine and Molecular Imaging (United States); Ennen, Rebecca E.; Sze, Daniel Y., E-mail: dansze@stanford.edu [Stanford University School of Medicine, Division of Interventional Radiology (United States)

    2013-12-15

    IntroductionA root cause analysis was performed on the occurrence of gastroduodenal ulceration after hepatic radioembolization (RE). We aimed to identify the risk factors in the treated population and to determine the specific mechanism of nontarget RE in individual cases. Methods: The records of 247 consecutive patients treated with yttrium-90 RE for primary (n = 90) or metastatic (n = 157) liver cancer using either resin (n = 181) or glass (n = 66) microspheres were reviewed. All patients who developed a biopsy-proven microsphere-induced gastroduodenal ulcer were identified. Univariate and multivariate analyses were performed on baseline parameters and procedural data to determine possible risk factors in the total population. Individual cases were analyzed to ascertain the specific cause, including identification of the culprit vessel(s) leading to extrahepatic deposition of the microspheres. Results: Eight patients (3.2 %) developed a gastroduodenal ulcer. Stasis during injection was the strongest independent risk factor (p = 0.004), followed by distal origin of the gastroduodenal artery (p = 0.004), young age (p = 0.040), and proximal injection of the microspheres (p = 0.043). Prolonged administrations, pain during administration, whole liver treatment, and use of resin microspheres also showed interrelated trends in multivariate analysis. Retrospective review of intraprocedural and postprocedural imaging showed a probable or possible culprit vessel, each a tiny complex collateral vessel, in seven patients. Conclusion: Proximal administrations and those resulting in stasis of flow presented increased risk for gastroduodenal ulceration. Patients who had undergone bevacizumab therapy were at high risk for developing stasis.

  9. Root Cause Analysis of Gastroduodenal Ulceration After Yttrium-90 Radioembolization

    International Nuclear Information System (INIS)

    Lam, Marnix G. E. H.; Banerjee, Subhas; Louie, John D.; Abdelmaksoud, Mohamed H. K.; Iagaru, Andrei H.; Ennen, Rebecca E.; Sze, Daniel Y.

    2013-01-01

    IntroductionA root cause analysis was performed on the occurrence of gastroduodenal ulceration after hepatic radioembolization (RE). We aimed to identify the risk factors in the treated population and to determine the specific mechanism of nontarget RE in individual cases. Methods: The records of 247 consecutive patients treated with yttrium-90 RE for primary (n = 90) or metastatic (n = 157) liver cancer using either resin (n = 181) or glass (n = 66) microspheres were reviewed. All patients who developed a biopsy-proven microsphere-induced gastroduodenal ulcer were identified. Univariate and multivariate analyses were performed on baseline parameters and procedural data to determine possible risk factors in the total population. Individual cases were analyzed to ascertain the specific cause, including identification of the culprit vessel(s) leading to extrahepatic deposition of the microspheres. Results: Eight patients (3.2 %) developed a gastroduodenal ulcer. Stasis during injection was the strongest independent risk factor (p = 0.004), followed by distal origin of the gastroduodenal artery (p = 0.004), young age (p = 0.040), and proximal injection of the microspheres (p = 0.043). Prolonged administrations, pain during administration, whole liver treatment, and use of resin microspheres also showed interrelated trends in multivariate analysis. Retrospective review of intraprocedural and postprocedural imaging showed a probable or possible culprit vessel, each a tiny complex collateral vessel, in seven patients. Conclusion: Proximal administrations and those resulting in stasis of flow presented increased risk for gastroduodenal ulceration. Patients who had undergone bevacizumab therapy were at high risk for developing stasis

  10. Controls on the composition and extraction of rare earth elements and yttrium (REY) in deep sea polymetallic nodules and sediments

    OpenAIRE

    Menendez Gamella, Amaya

    2017-01-01

    Rising demand for metals is driving a search for new mineral resources and mining of seafloor deposits is likely to commence in the next few years. These include polymetallic nodules and crusts that are highly enriched in Mn, Co, Ni, Cu, Mo, Li and Te, and deep-sea clays that can contain high concentrations of the rare earth elements and yttrium (REY). The potential environmental impacts of mining these deposits are, however, poorly constrained and a better understanding of the processes that...

  11. The effects of alumina nanofillers on mechanical properties of high-performance epoxy resin.

    Science.gov (United States)

    Zhang, Hui; Zhang, Hui; Tang, Longcheng; Liu, Gang; Zhang, Daijun; Zhou, Lingyun; Zhang, Zhong

    2010-11-01

    In the past decade extensive studies have been focused on mechanical properties of inorganic nanofiller/epoxy matrices. In this work we systematically investigated the mechanical properties of nano-alumina-filled E-54/4, 4-diaminodiphenylsulphone (DDS) epoxy resins, which were prepared via combining high-speed mixing with three-roll milling. Homogeneous dispersion of nano-alumina with small agglomerates was obtained in epoxy resin, which was confirmed using transmission electron microscopy (TEM). The static/dynamic modulus, tensile strength and fracture toughness of the nanocomposites were found to be simultaneously enhanced with addition of nano-alumina fillers. About 50% and 80% increases of K(IC) and G(IC) were achieved in nanocomposite filled with 18.4 wt% alumina nanofillers, as compared to that of the unfilled epoxy resin. Furthermore, the corresponding fracture surfaces of tensile and compact tension samples were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques in order to identify the relevant fracture mechanisms involved. Various fracture features including cavities/debonding of nanofiller, local plastic deformation as well as crack pinning/deflection were found to be operative in the presence of nano-alumina fillers.

  12. Adsorption Behavior of Vanadium in Presence of alumina with Emphasize on Triple Layer Model Simulation

    International Nuclear Information System (INIS)

    El-Sayed, A.A.

    2006-01-01

    Adsorption behavior of vanadium in alumina colloidal solution as simulation for soil-water and/or sediment - water system was investigated. factors affecting this behavior including Ph, humic acid and alumina concentrations were studied. Three stages of vanadium adsorption on alumina were approved due to Ph changes. The first is increasing adsorption with increasing Ph, in the range 1-3. the second is decreasing adsorption with increasing Ph in the range 6-10. the third is constant adsorption at 100% adsorption in Ph range 3-8 at 10 g/l concentration of alumina. However, at 0.2 g/l, the maximum adsorption of vanadium became less than 100%.The effect of humic acid on the adsorption behavior of vanadium (V) was studied and compared with that of vanadium (IV) . Adsorption behaviors were studied at concentration 4.1 E-4 M for vanadium at 0.1 M ionic strength. Triple layer model was used for simulation of vanadium adsorption behavior in presence of alumina under the same working conditions. the results showed good validation and verification to the data practically found. speciation of vanadium in both homogenous and heterogeneous systems was also studied theoretically so as to verify the most abundant elemental species and its impact on the environment

  13. LOW TEMPERATURE SINTERING OF ALUMINA BIOCERAMIC UNDER NORMAL PRESSURE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Superfine alumina powder with high purity (mean particle size is less than 0. 35μm) were used as main starting material for sintering alumina ceramic. A multiple additive MgO-ZrO2 (Y2O3) was homogeneously added into the batch by the chemical coprecipitation method. Sintering of alumina bioceramic at low tempera ture (<1600C) was achieved resulting in a dense and high strength alumina ceramic with the bending strength up to 382 MPa and an improved fracture toughness. Mechanism that the multiple additives promote the sintering of alumina ceramic is discussed on the base of XRD and SEM analysis.

  14. Investigating the property profile of polyamide-alumina nanocomposite materials

    International Nuclear Information System (INIS)

    Sarwar, Muhammad Ilyas; Zulfiqar, Sonia; Ahmad, Zahoor

    2009-01-01

    Transparent sol-gel-derived nanocomposites were prepared by incorporating an alumina network into a polyamide matrix. Different amounts of aluminum butoxide were hydrolyzed and condensed to produce the alumina network. Thin composite films were characterized in terms of their optical, morphological, mechanical and thermomechanical properties. Tensile modulus, stress at both yield and break points, improved for alumina loadings of 5-10 wt.%. The glass transition temperature increased to 140 o C for nanocomposites containing 15 wt.% alumina. Scanning electron microscopy investigations indicated a uniform distribution of alumina in the polyamide matrix.

  15. Mechanical Properties of Plasma Sprayed Alumina Coatings

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Nohava, Jiří; Siegel, J.

    2003-01-01

    Roč. 48, č. 2 (2003), s. 129-145 ISSN 0001-7043 R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma sprayed alumina coatings, fatigue test, metalography, fractography, residual stress, microhardness, Young's modulus , four-point bending Subject RIV: BL - Plasma and Gas Discharge Physics

  16. Yield stress of alumina-zirconia suspensions

    International Nuclear Information System (INIS)

    Ramakrishnan, V.; Pradip; Malghan, S.G.

    1996-01-01

    The yield stress of concentrated suspensions of alumina, zirconia, and mixed alumina-zirconia powders was measured by the vane technique as a function of solids loading, relative amounts of alumina and zirconia, and pH. At the isoelectric point (IEP), the yield stress varied as the fourth power of the solids loading. The relative ratio of alumina and zirconia particles was important in determining the yield stress of the suspension at the IEP. The yield stress of single and mixed suspensions showed a marked variation with pH. The maximum value occurred at or near the IEP of the suspension. The effect of electrical double-layer forces on the yield stress can be described on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A normalized yield stress--that is, the ratio of the yield stress at a given pH to the yield stress at the IEP predicted by this model--showed good correlation with experimental data

  17. Wear of alumina on alumina total hip prosthesis - effect of lubricant on hip simulator test

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, M.; Amino, H. [Kyocera Corp., Fushimi, Kyoto (Japan). Bioceram Div.; Oonishi, H. [Dept. of Orthopaedic Surgery, Artificial Joint Sect. and Biomat. Res. Lab., Osaka Minami National Hospital, Osaka (Japan); Clarke, I.C.; Good, V. [Dept. of Orthopaedic Surgery, Loma Linda Univ. Medical Center, CA (United States)

    2001-07-01

    The complex wear-friction-lubrication behavior of alumina on alumina combination in total hip prostheses (THP) was investigated using a hip joint simulator. The objectives of this study were to evaluate the effect of the ball/cup clearance and of the lubricant conditions. Alumina bearings were categorized in three diametrical clearances, 20-30, 60-70 and 90-100 micrometer, three each and wear tests were carried out with 90% bovine serum. There was no significant difference between three groups. Volumetric wear in the run-in phase for all tested nine ceramic liners averaged 0.27mm{sup 3}/million cycles and in the steady-state phase averaged 0.0042mm{sup 3}/million cycles. In addition to the 90% serum, 27% serum and saline were used as the lubricant for evaluate the effect of serum concentration on alumina on alumina wear couples. The wear test results showed that in all tested conditions the wear trends of alumina BEARING were bi-phasic and wear volume could be affected by the serum concentration. Both ''Run-in'' and ''Steady-state'' wear rates in 90% bovine serum were three times higher than those in saline. (orig.)

  18. Nanoporous hard data: optical encoding of information within nanoporous anodic alumina photonic crystals.

    Science.gov (United States)

    Santos, Abel; Law, Cheryl Suwen; Pereira, Taj; Losic, Dusan

    2016-04-21

    Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information.

  19. Alumina reinforced tetragonal zirconia (TZP) composites. Final technical report, July 1, 1993--December 31, 1996

    International Nuclear Information System (INIS)

    Shetty, D.K.

    1997-01-01

    This final technical report summarizes the significant research results obtained during the period July 1, 1993 through December 31, 1996 in the DOE-supported research project entitled, open-quotes Alumina Reinforced Tetragonal Zirconia (TZP) Compositesclose quotes. The objective of the research was to develop high-strength and high-toughness ceramic composites by combining mechanisms of platelet, whisker or fiber reinforcement with transformation toughening. The approach used included reinforcement of Celia- or yttria-partially-stabilized zirconia (Ce-TZP or Y-TZP) with particulates, platelets, or continuous filaments of alumina

  20. Adsorption of pesticides onto quartz, calcite, kaolinite, and α-alumina

    DEFF Research Database (Denmark)

    Clausen, Liselotte; Fabricius, Ida Lykke; Madsen, L.

    2001-01-01

    adsorption characteristics of selected pesticides. Investigated mineral phases included quartz, calcite, kaolinite, and alpha -alumina. Selected pesticides comprised atrazine (6-chloro-N-2-ethyl-N-4-isopropyl-1,3,5-triazine-2,4-diamine isoproturon [3-(4-isopropyl-phenyl)-1,1-dimethylurea)], mecoprop [(RS)-2...... due to formation of Ca-pesticide-surface complexes. Adsorption of the uncharged pesticides (atrazine and isoproturon) was detected only on kaolinite. The lack of adsorption on alpha -alumina indicates that the uncharged pesticides have a greater affinity for the silanol surface sites (= SiOH) than...

  1. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  2. Preparation of high purity yttrium single crystals by electrotransport

    International Nuclear Information System (INIS)

    Volkov, V.T.; Nikiforova, T.V.; Ionov, A.M.; Pustovit, A.N.; Sikharulidse, G.G.

    1981-01-01

    The possibility of obtaining yttrium crystals of high purity by the method of solid state electrotransport (SSE) was investigated in the present work. The behaviour of low contents of iron, aluminium, silicon, tantalum, copper, silver and vanadium as metallic impurities was studied using mass spectrometry. It is shown that all the impurities investigated, except copper, migrate to the anode. During electrotransfer a purification with respect to these impurities by a factor of 4 - 6 is obtained. It is proposed that the diffusion coefficients of the metallic impurities investigated are anomalously high and that the behaviour of the impurities during SSE in adapters necessitates further investigation. By using a three-stage process with intermediate removal of the anode end yttrium single crystals with a resistance ratio rho 293 /rhosub(4.2)=570 were produced. (Auth.)

  3. Creep properties of a thermally grown alumina

    Energy Technology Data Exchange (ETDEWEB)

    Kang, K.J. [Department of Mechanical Engineering, Chonnam National University, Kwangju 500-757 (Korea, Republic of)], E-mail: kjkang@chonnam.ac.kr; Mercer, C. [Materials Department, University of California, Santa Barbara, CA 93106-5050 (United States)

    2008-04-15

    A unique test system has been developed to measure creep properties of actual thermally grown oxides (TGO) formed on a metal foil. The thickness of TGO, load and displacement can be monitored in situ at high temperature. Two batches of FeCrAlY alloys which differ from each other in contents of yttrium and titanium were selected as the {alpha}-Al{sub 2}O{sub 3} TGO forming materials. The creep tests were performed on {alpha}-Al{sub 2}O{sub 3} of thickness 1-4 {mu}m, thermally grown at 1200 deg. C in air. The strength of the substrate was found to be negligible, provided that the TGO and substrate thickness satisfy: h{sub TGO} > 1 {mu}m and H{sub sub} {<=} 400 {mu}m. The steady-state creep results for all four TGO thicknesses obtained on batch I reside within a narrow range, characterized by a parabolic creep relation. It is nevertheless clear that the steady-state creep rates vary with TGO thickness: decreasing as the thickness increases. For batch II, the steady-state creep rates are higher and now influenced more significantly by TGO thickness. In comparison with previous results of the creep properties for bulk polycrystalline {alpha}-Al{sub 2}O{sub 3} at a grain size of {approx}2 {mu}m, the creep rates for the TGO were apparently higher, but both were significantly affected by yttrium content. The higher creep rate and dependency on the TGO thickness led to a hypothesis that the deformation of the TGO under tensile stress at high temperature was not a result of typical creep mechanisms such as diffusion of vacancies or intra-granular motion of dislocations, but a result of inter-grain growth of TGO. Results also indicate that the amount of yttrium may influence the growth strain as well as the creep rate.

  4. Scratch induced failure of plasma sprayed alumina based coatings

    International Nuclear Information System (INIS)

    Hazra, S; Bandyopadhyay, P.P.

    2012-01-01

    Highlights: ► Scratch induced failure of alumina based coatings including nanostructured is reported. ► Ceramic is deposited on bond coat instead of steel, emulating a realistic situation. ► Lateral force data is supplemented with microscopy to observe coating failure. ► The failure mechanism during scratching has been identified. ► Critical load of failure has been calculated for each bond-top coat combination. -- Abstract: A set of plasma sprayed coatings were obtained from three alumina based top coat and two bond coat powders. Scratch test was undertaken on these coatings, under constant and linearly varying load. Test results include the lateral force data and scanning electron microscope (SEM) images. Failure occurred by large area spallation of the top coat and in most cases tensile cracks appeared on the exposed bond coat. The lateral force showed an increasing trend with an increase in normal load up to a certain point and beyond this, it assumed a steady average value. The locations of coating spallation and occurrence of maximum lateral force did not coincide. A bond coat did not show a significant role in determining the scratch adhesion strength.

  5. Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification

    Energy Technology Data Exchange (ETDEWEB)

    Lamouri, S.; Hamidouche, M.; Bouaouadja, N.; Belhouchet, H.; Garnier, V.; Fantozzi, G.; Trelkat, J.F.

    2017-07-01

    In this work, we studied the aptitude to sintering green bodies using γ-Al2O3 transition alumina as raw powder. We focused on the influence of the heating rate on densification and microstructural evolution. Phase transformations from transition alumina γ→δ→θ→α-Al2O3 were studied by in situ X-rays diffraction from the ambient to 1200°C. XRD patterns revealed coexistence of various phase transformations during the heating cycle. DTA and dilatometry results showed that low heating rate leads to a significant reduction of the temperature of the α-Al2O3 alumina formation. Around 1190, 1217 and 1240°C were found when using 5, 10 and 20°C/min of heating rate, respectively. The activation energy for θ-Al2O3→α-Al2O3 transformation calculated by Kissinger and JMA equations using dilatometry method were 464.29 and 488.79kJ/mol, respectively and by DTA method were 450.72 and 475.49kJ/mol, respectively. In addition, the sintering of the green bodies with low heating rate promotes the rearrangement of the grains during θ-Al2O3→α-Al2O3 transformation, enhancing the relative density to 95% and preventing the development of a vermicular structure. (Author)

  6. Acromegaly with sleep disturbances relieved by yttrium-90 pituitary implantation

    International Nuclear Information System (INIS)

    Rosenstock, J.; Doyle, F.H.; Joplin, G.F.; Jung, R.T.; Mashiter, K.

    1982-01-01

    A brief case history is presented of a patient, who, after yttrium-90 implantation, showed a complete clinical and hormonal remission of her acromegaly, maintaining normal pituitary function. The remarkable feature was the rapid disappearance of her attacks of somnolence within 96 hours of pituitary implantation, despite persistence of nocturnal snoring and well before any remodelling of soft tissues could have occurred. This response suggests that her daytime somnolence had a narcoleptic component. (author)

  7. Temperature dependence of sound velocity in yttrium ferrite

    International Nuclear Information System (INIS)

    L'vov, V.A.

    1979-01-01

    The effect of the phonon-magnon and phonon-phonon interoctions on the temperature dependence of the longitudinal sound velocity in yttrium ferrite is considered. It has been shown that at low temperatures four-particle phonon-magnon processes produce the basic contribution to renormalization of the sound velocity. At higher temperatures the temperature dependence of the sound velocity is mainly defined by phonon-phonon processes

  8. Acromegaly with sleep disturbances relieved by yttrium-90 pituitary implantation

    Energy Technology Data Exchange (ETDEWEB)

    Rosenstock, J.; Doyle, F.H.; Joplin, G.F.; Jung, R.T.; Mashiter, K. (Hammersmith Hospital, London (UK). Postgraduate Medical School)

    1982-03-01

    A brief case history is presented of a patient, who, after yttrium-90 implantation, showed a complete clinical and hormonal remission of her acromegaly, maintaining normal pituitary function. The remarkable feature was the rapid disappearance of her attacks of somnolence within 96 hours of pituitary implantation, despite persistence of nocturnal snoring and well before any remodelling of soft tissues could have occurred. This response suggests that her daytime somnolence had a narcoleptic component.

  9. Growth and scintillation properties of gadolinium and yttrium orthovanadate crystals

    International Nuclear Information System (INIS)

    Voloshina, O.V.; Baumer, V.N.; Bondar, V.G.; Kurtsev, D.A.; Gorbacheva, T.E.; Zenya, I.M.; Zhukov, A.V.; Sidletskiy, O.Ts.

    2012-01-01

    Aiming to explore the possibility of using the undoped rare-earth orthovanadates as scintillation materials, we developed the procedure for growth of gadolinium (GdVO 4 ) and yttrium (YVO 4 ) orthovanadate single crystals by Czochralski method, and determined the optimal conditions of their after-growth annealing. Optical, luminescent, and scintillation properties of YVO 4 and GdVO 4 were discussed versus known literature data. Scintillation characteristics of GdVO 4 were determined for the first time.

  10. Treatment of exhaust fluorescent lamps to recover yttrium: Experimental and process analyses

    International Nuclear Information System (INIS)

    De Michelis, Ida; Ferella, Francesco; Varelli, Ennio Fioravante; Veglio, Francesco

    2011-01-01

    Highlights: → Recovery of yttrium from spent fluorescent lamps by sulphuric acid leaching. → The use of sulphuric acid allows to reduce calcium dissolutions. → Main contaminant of fluorescent powder are Si, Pb, Ca and Ba. → Hydrated yttrium oxalate, recovered by selective precipitation, is quite pure (>90%). → We have studied the whole process for the treatment of dangerous waste (plant capability). - Abstract: The paper deals with recovery of yttrium from fluorescent powder coming from dismantling of spent fluorescent tubes. Metals are leached by using different acids (nitric, hydrochloric and sulphuric) and ammonia in different leaching tests. These tests show that ammonia is not suitable to recover yttrium, whereas HNO 3 produces toxic vapours. A full factorial design is carried out with HCl and H 2 SO 4 to evaluate the influence of operating factors. HCl and H 2 SO 4 leaching systems give similar results in terms of yttrium extraction yield, but the last one allows to reduce calcium extraction with subsequent advantage during recovery of yttrium compounds in the downstream. The greatest extraction of yttrium is obtained by 20% w/v S/L ratio, 4 N H 2 SO 4 concentration and 90 deg. C. Yttrium and calcium yields are nearly 85% and 5%, respectively. The analysis of variance shows that acid concentration alone and interaction between acid and pulp density have a significant positive effect on yttrium solubilization for both HCl and H 2 SO 4 medium. Two models are empirically developed to estimate yttrium and calcium concentration during leaching. Precipitation tests demonstrate that at least the stoichiometric amount of oxalic acid is necessary to recover yttrium efficiently and a pure yttrium oxalate n-hydrate can be produced (99% grade). The process is economically feasible if other components of the fluorescent lamps (glass, ferrous and non-ferrous scraps) are recovered after the equipment dismantling and valorized, besides the cost that is usually paid

  11. Thermoelectric Properties of the Yttrium-Doped Ceramic Oxide SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Tamal Tahsin; Ur, Soon-Chul [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-01-15

    The doping dependence of the thermoelectric figure of merit, ZT, of the ceramic oxide SrTiO{sub 3} at high temperature has been studied. In this study, yttrium was used as the doping element. A conventional solid-state reaction method was used for the preparation of Y-doped SrTiO{sub 3}. The doping level in SrTiO{sub 3} was controlled to be in the doping range of 2 - 10 mole%. Almost all the yttrium atoms incorporated into the SrTiO{sub 3} provided charge carriers, as was observed by using X-ray diffraction pattern. The relative densities of all the samples varied from 98.53% to 99.45%. The thermoelectric properties, including the electrical conductivity σ, Seebeck coefficient S, thermal conductivity k, and the figure of merit, ZT, were investigated at medium temperatures. The ZT value showed an obvious doping level dependence, in which a value as high as 0.18 is realized at 773 K for a doping of 8 mole%.

  12. Comparison of the air oxidation behaviors of Zircaloy-4 implanted with yttrium and cerium ions at 500 deg. C

    International Nuclear Information System (INIS)

    Chen, X.W.; Bai, X.D.; Xu, J.; Zhou, Q.G.; Chen, B.S.

    2002-01-01

    As a valuable process for surface modification of materials, ion implantation is eminent to improve mechanical properties, electrochemical corrosion resistance and oxidation behaviors of varieties of materials. To investigate and compare the oxidation behaviors of Zircaloy-4, implantation of yttrium ion and cerium ion were respectively employed by using an MEVVA source at the energy of 40 keV with a dose ranging from 1x10 16 to 1x10 17 ions/cm 2 . Subsequently, weight gain curves of the different specimens including as-received Zircaloy-4 and Zircaloy-4 specimens implanted with the different ions were measured after oxidation in air at 500 deg. C for 100 min. It was obviously found that a significant improvement was achieved in the oxidation behaviors of implanted Zircaloy-4 compared with that of the as-received Zircaloy-4, and the oxidation behavior of cerium-implanted Zircaloy-4 was somewhat better than that of yttrium-implanted specimen. To obtain the valence and the composition of the oxides in the scale, X-ray photoemission spectroscopy was used in the present study. Glancing angle X-ray diffraction, employed to analyze the phase transformation in the oxide films, showed that the addition of yttrium transformed the phase from monoclinic zirconia to tetragonal zirconia, yet the addition of cerium transformed the phase from monoclinic zirconia to hexagonal zirconia. In the end, the mechanism of the improvement of the oxidation behavior was discussed

  13. Surface functionalization of nanoporous alumina with bone morphogenetic protein 2 for inducing osteogenic differentiation of mesenchymal stem cells

    International Nuclear Information System (INIS)

    Song, Yuanhui; Ju, Yang; Morita, Yasuyuki; Xu, Baiyao; Song, Guanbin

    2014-01-01

    Many studies have demonstrated the possibility to regulate cellular behavior by manipulating the specific characteristics of biomaterials including the physical features and chemical properties. To investigate the synergistic effect of chemical factors and surface topography on the growth behavior of mesenchymal stem cells (MSCs), bone morphorgenic protein 2 (BMP2) was immobilized onto porous alumina substrates with different pore sizes. The BMP2-immobilized alumina substrates were characterized with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Growth behavior and osteogenic differentiation of MSCs cultured on the different substrates were investigated. Cell adhesion and morphological changes were observed with SEM, and the results showed that the BMP2-immobilized alumina substrate was able to promote adhesion and spreading of MSCs. MTT assay and immunofluorescence staining of integrin β1 revealed that the BMP2-immobilized alumina substrates were favorable for cell growth. To evaluate the differentiation of MSCs, osteoblastic differentiation markers, such as alkaline phosphatase (ALP) activity and mineralization, were investigated. Compared with those of untreated alumina substrates, significantly higher ALP activities and mineralization were detected in cells cultured on BMP2-immobilized alumina substrates. The results suggested that surface functionalization of nanoporous alumina substrates with BMP2 was beneficial for cell growth and osteogenic differentiation. With the approach of immobilizing growth factors onto material substrates, it provided a new insight to exploit novel biofunctional materials for tissue engineering. - Highlights: • BMP2 was immobilized onto nanoporous alumina substrates with different pore sizes. • BMP2-immobilized substrates were able to promote adhesion and spreading of MSCs. • BMP2-immobilized substrates were favorable for cell growth of MSCs. • BMP2-immobilized substrates promoted osteogenic

  14. The determination of the structure of γ-alumina using empirical and first principle calculations and supporting experiment

    International Nuclear Information System (INIS)

    Paglia, G.; Buckely, C.E.; O'Connor, B.H.; Van Riessen, A.; Rohl, A.L.; Gale, J.D.

    2002-01-01

    Full text: Because of its hardness, abrasion resistance, mechanical strength, corrosion resistance, and good electrical insulation, alumina (AI 2 O 3 ) is a material of high technological and industrial significance. Alumina exists in a variety of metastable structures including the γ, η, θ, K, and χ aluminas, as well as its stable α alumina phase. The crystal structure of the γ-phase in alumina has attracted considerable attention over the past 40 years, with various reports attributing either a cubic or tetragonal structure to this phase. Consensus on the definitive structure of γ-alumina (γ-AI 2 O 3 ) has yet to be reached. Rapid advancement has occurred in the field of computational materials science in recent times. Huge advances in computing power during this period have made ft possible to apply the laws of quantum mechanics to the study of macroscopic properties of real materials at the atomic level. Predicting the properties of materials by theoretical means complements the traditional experimental approaches. This research is directed at determining the structure of γ-Al 2 O 3 using theoretical first principles and empirical computational techniques combined with experimental methods. The purpose of this presentation is to discuss the problems associated with determining the structure of γ-AI 2 O 3 and to outline the methodology being applied to solve it. Copyright (2002) Australian X-ray Analytical Association Inc

  15. Mechanical properties of ion-implanted alumina

    International Nuclear Information System (INIS)

    Pope, S.G.

    1988-01-01

    Monolithic oxide ceramics are being proposed as structural materials in continuously more-demanding applications. The demands being placed on these materials have caused concern pertaining to the continued growth of oxide structural ceramics due to limited toughness. The realization that ceramic strength and toughness can be affected by surface conditions has led to many surface-modification techniques, all striving to improve the mechanical properties of ceramics. Along these lines, the effects of ion implantation as a surface modification technique for improvement of the mechanical properties of alumina were studied. Initially, sapphire samples were implanted with elemental ion species that would produce oxide precipitates within the sapphire surface when annealed in an oxygen-containing atmosphere. Optimum conditions as determined from implantation into sapphire were then used to modify a polycrystalline alumina. Specific modifications in microhardness, indentation fracture toughness and flexure strength are reported for the parameters studied. Microstructure and phase relationships related to modified surfaces properties are also reported

  16. Microstructural evolution of alumina-zirconia nanocomposites

    International Nuclear Information System (INIS)

    Ojaimi, C.L.; Chinelatto, A.S.A.; Chinelatto, A.L.; Pallone, E.M.J.A.

    2012-01-01

    Ceramic materials have limited use due to their brittleness. The inclusion of nanosized particles in a ceramic matrix, which are called nanocomposites, and ceramic processing control by controlling the grain size and densification can aid in obtaining ceramic products of greater strength and toughness. Studies showed that the zirconia nano inclusions in the matrix of alumina favors an increase in mechanical properties by inhibiting the grain growth of the matrix and not by the mechanism of the transformation toughening phase of zirconia. In this work, the microstructural evolution of alumina nanocomposites containing 15% by volume of nanometric zirconia was studied. From the results it was possible to understand the sintering process of these nanocomposites. (author)

  17. Influence of alumina characteristics on glaze properties

    Directory of Open Access Journals (Sweden)

    Arrufat, S.

    2010-10-01

    Full Text Available Aluminium oxide is a synthetic raw material manufactured from bauxite by the Bayer process, whose Al2O3 content typically exceeds 99%. Four main types of alumina can be defined, depending on the processing used: hydrargillite Al(OH3, boehmite AlOOH, transition aluminas (calcined at low temperatures, 1000 °C, with an intermediary crystallographic structure between hydrates and alpha alumina, and α-Al2O3 (calcined at high temperatures, >1100 °C. In glaze manufacturing, α-Al2O3 is the main type of alumina used. This raw material acts as a matting agent: the matt effect depends on alumina particle size and content in the glaze. This study examines the effect of the degree of alumina calcination on glaze technical and aesthetic properties. For this purpose, aluminas with different degrees of calcination were added to a glaze formulated with a transparent frit and kaolin, in order to simplify the system to be studied. The results show that, depending on the degree of calcination, alumina particles can react with the glaze components (SiO2, CaO, and ZnO to form new crystalline phases (anorthite and gahnite. Both crystallisations extract CaO and ZnO from the glassy phase, increasing glassy phase viscosity. The variation in crystalline phases and glassy phase viscosity yields glazes with different technical and aesthetic properties.

    El óxido de aluminio es una materia prima sintética fabricada a partir de la bauxita por medio del proceso Bayer, cuyo contenido de Al2O3 supera, por regla general, el 99%. Se pueden definir cuatro tipos de alúmina, en función del tipo de proceso usado: hidrargilita Al(OH3, boehmita AlOOH, alúminas de transición (calcinadas a bajas temperaturas, 1000 °C, con una estructura cristalográfica intermedia entre los hidratos y la alfa alúmina, y la α-Al2O3 (calcinada a

  18. Mesoscale Modelling of the Response of Aluminas

    International Nuclear Information System (INIS)

    Bourne, N. K.

    2006-01-01

    The response of polycrystalline alumina to shock is not well addressed. There are several operating mechanisms that only hypothesized which results in models which are empirical. A similar state of affairs in reactive flow modelling led to the development of mesoscale representations of the flow to illuminate operating mechanisms. In this spirit, a similar effort is undergone for a polycrystalline alumina. Simulations are conducted to observe operating mechanisms at the micron scale. A method is then developed to extend the simulations to meet response at the continuum level where measurements are made. The approach is validated by comparison with continuum experiments. The method and results are presented, and some of the operating mechanisms are illuminated by the observed response

  19. Grinding mechanism of zirconia toughened alumina

    International Nuclear Information System (INIS)

    Tsukuda, A.; Kondo, Y.; Yokota, K.

    1998-01-01

    In the grinding process, physical properties of ceramics affect both grinding mechanism and quality of ground surface. In this study we focused on fracture toughness of ceramics and the effect on grinding. A grinding test was carried out by single point grinding for ten different zirconia toughened alumina ceramics with different monoclinic zirconia contents. Effects of zirconia contents on the grinding mechanism and crack initiation were discussed. Copyright (1998) AD-TECH - International Foundation for the Advancement of Technology Ltd

  20. Performance characteristics of porous alumina ceramic structures

    International Nuclear Information System (INIS)

    Latella, B.A.; Liu, T.

    2000-01-01

    Porous ceramics have found a wide range of applications as filters for liquids and gases. The suitability of materials for use in these types of applications depends on the microstructure (grain size, pore size and pore volume fraction) and hence the mechanical and thermal properties. In this study alumina ceramics with different levels of porosity and controlled pore sizes were fabricated and the surface damage and fracture properties were examined. Copyright (2000) The Australian Ceramic Society

  1. In-beam dielectric properties of alumina

    International Nuclear Information System (INIS)

    Molla, J.; Ibarra, A.; Hodgson, E.R.

    1995-01-01

    The dielectric properties (permittivity and loss tangent) of a 99.7% purity alumina grade have been measured over a wide frequency range (1 kHz-15 GHz) before and after 2 MeV electron irradiation at different temperatures. The dielectric properties at 15 GHz were measured during irradiation. Both prompt and fluence effects are observed together with permanent changes which continue to evolve following irradiation. The behaviour is complex, consistent with both radiation induced electronic effects and aggregation processes. ((orig.))

  2. Separation of tungsten and rhenium on alumina

    Directory of Open Access Journals (Sweden)

    MILOVAN SM. STOILJKOVIC

    2004-09-01

    Full Text Available The conditions for the efficient separation of tungsten(VI and rhenium (VII on alumina were established. The distribution coefficients Kd for tungstate and perrhenate anions, as well as the separation factors a (a = KdWO42-/Kd ReO4- were determined using hydrochloric or nitric acid as the aqueous media. A solution of sodium chloride in the pH range 2–6 was also examined. Under all the tested experimental conditions, alumina is a much better adsorbent for tungsten than for rhenium. The obtained results indicated that the best separation of these two elements is achieved when 0.01– 0.1 mol dm-3 HCl or 1.0 mol dm-3 HNO3 are used as the aqueous media. If NaCl is used as the aqueous phase, the best separation is achieved with 0.20 mol dm-3 NaCl, pH 4–6. Under these experimental conditions, the breakthrough and saturation capacities of alumina for tungsten at pH 4 are 17 and 26 mg W/g Al2O3, respectively. With increasing pH, these values decrease. Thus, at pH 6 they are only 4 and 13 mg W/g Al2O3, respectively.

  3. High contrast laser marking of alumina

    Science.gov (United States)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-05-01

    Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

  4. Slip cast coating of alumina crucibles

    International Nuclear Information System (INIS)

    Haroun, N.A.; El-Masry, M.A.A.

    1980-01-01

    The development of a process for coating alumina crucibles with MgO protective coat in a two-step slip casting operation is described. The best milling conditions for the alumina used were wet ball milling for 24 hr. MgO had to be calcined at 1200 0 C to minimize hydration. Optimum slip casting conditions for alumina and magnesia were found to be L/S I and pH 3-6 or 9-II for the former, and L/S 3 (alcohol) and pH 8.5-10 for the latter. Sintering of Al 2 O 3 and MgO in the temperature range 1150-500 0 C was investigated. Additions of NiO and MgO lowered the sintered densities at lower temperatures but improved the densification at 1500 0 C. Near theoretical density Al 2 O 3 and MgO crucibles were obtained. A two-step slip casting technique was developed to coat Al 2 O 3 with MgO. Certain slow firing schedules could eliminate the otherwise observed coat-crucible separation and cracks. (author)

  5. Preparation and Characterization of Activated Alumina

    Science.gov (United States)

    Rabia, A. R.; Ibrahim, A. H.; Zulkepli, N. N.

    2018-03-01

    Activated alumina is a high surface area and highly porous form of aluminum oxide that can be employed for contaminant species adsorb from ether gases or liquids without changing its form. The research in getting this material has generated huge interested. Thus, this paper presented preparation of activated alumina from chemical process. Pure aluminum (99.9% pure) reacted at room temperature with an aqueous NaOH in a reactor to produce a solution of sodium aluminate (NaAlO2). This solution was passed through filter paper and the clear filtrate was neutralized with H2SO4, to pH 6, 7 or 8, resulting in the precipitation of a white gel, Al(OH)3·XH2O. The washed gel for sulfate ions were dried at 80 °C for 6 h, a 60 mesh sieve was to separate and sort them into different sizes. The samples were then calcined (burn) for 3h in a muffle furnace, in air, at a heating rate of 2 °C min-1. The prepared activated alumina was further characterized for better understanding of its physical properties in order to predict its chemical mechanism.

  6. YSZ-Reinforced Alumina Multi-Channel Capillary Membranes for Micro-Filtration.

    Science.gov (United States)

    Wang, Bo; Lee, Melanie; Li, Kang

    2015-12-30

    The combined phase-inversion and sintering method not only produces ceramic hollow fibre membranes with much lower fabrication costs than conventional methods, but these membranes can also be designed to have greatly reduced transport resistances for filtration processes. The bottleneck of this technique is the weak mechanical property of the fibres, due to the small dimensions and the brittle nature of the ceramic materials. In this study, yttrium stabilised zirconia (YSZ) reinforced alumina seven-channel capillary microfiltration membranes were prepared with a pore size of ~230 nm and their mechanical property and permeation characteristics were studied. It is found that the addition of YSZ can effectively enhance the mechanical property of the membrane and also increase pure water permeation flux. The Al₂O₃-YSZ seven-channel capillary membranes could reach a fracture load of 23.4 N and a bending extension of 0.54 mm when being tested with a 6 cm span, to meet the requirements for most industrial microfiltration applications.

  7. YSZ-Reinforced Alumina Multi-Channel Capillary Membranes for Micro-Filtration

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2015-12-01

    Full Text Available The combined phase-inversion and sintering method not only produces ceramic hollow fibre membranes with much lower fabrication costs than conventional methods, but these membranes can also be designed to have greatly reduced transport resistances for filtration processes. The bottleneck of this technique is the weak mechanical property of the fibres, due to the small dimensions and the brittle nature of the ceramic materials. In this study, yttrium stabilised zirconia (YSZ reinforced alumina seven-channel capillary microfiltration membranes were prepared with a pore size of ~230 nm and their mechanical property and permeation characteristics were studied. It is found that the addition of YSZ can effectively enhance the mechanical property of the membrane and also increase pure water permeation flux. The Al2O3-YSZ seven-channel capillary membranes could reach a fracture load of 23.4 N and a bending extension of 0.54 mm when being tested with a 6 cm span, to meet the requirements for most industrial microfiltration applications.

  8. Cold Spray Aluminum–Alumina Cermet Coatings: Effect of Alumina Content

    Science.gov (United States)

    Fernandez, Ruben; Jodoin, Bertrand

    2018-04-01

    Deposition behavior and deposition efficiency were investigated for several aluminum-alumina mixture compositions sprayed by cold spray. An increase in deposition efficiency was observed. Three theories postulated in the literature, explaining this increase in deposition efficiency, were investigated and assessed. Through finite element analysis, the interaction between a ceramic particle peening an impacting aluminum particle was found to be a possible mechanism to increase the deposition efficiency of the aluminum particle, but a probability analysis demonstrated that this peening event is too unlikely to contribute to the increment in deposition efficiency observed. The presence of asperities at the substrate and deposited layers was confirmed by a single-layer deposition efficiency measurement and proved to be a major mechanism in the increment of deposition efficiency of the studied mixtures. Finally, oxide removal produced by the impact of ceramic particles on substrate and deposited layers was evaluated as the complement of the other effects and found to also play a major role in increasing the deposition efficiency. It was found that the coatings retained approximately half of the feedstock powder alumina content. Hardness tests have shown a steady increase with the coating alumina content. Dry wear tests have revealed no improvement in wear resistance in samples with an alumina content lower than 22 wt.% compared to pure aluminum coatings. Adhesion strength showed a steady improvement with increasing alumina content in the feedstock powder from 18.5 MPa for pure aluminum coatings to values above 70 MPa for the ones sprayed with the highest feedstock powder alumina content.

  9. Tribological and stability investigations of alkylphosphonic acids on alumina surface

    International Nuclear Information System (INIS)

    Cichomski, M.; Kośla, K.; Grobelny, J.; Kozłowski, W.; Szmaja, W.

    2013-01-01

    Alumina substrates are commonly used for various micro-/nanoelectromechanical systems (MEMS/NEMS). For efficient and lifetime longevity of these devices, lubricant films of self-assembled monolayers (SAMs) with nanometer thickness are increasingly being employed. In the present paper, we report preparation, tribological and stability investigations of alkylphosphonic acids on the alumina surface. The alkylphosphonic acids were prepared on the alumina surface using the liquid phase deposition method. The effectiveness of modification of the alumina surface by alkylphosphonic acids was investigated using water contact angle measurements, secondary ion mass spectrometry, X-ray photoelectron and infrared spectroscopy. Frictional behavior in milinewton load range was studied by microtribometry. It is shown that surface modification of the alumina surface by alkylphosphonic acids reduces the coefficient of friction values compared to the unmodified alumina. In comparison to the non-modified alumina surface, all tested alkylphosphonic acids cause a decrease in the friction coefficients in friction tests for counterparts made from different materials, such as steel, zirconia and silicon nitride. It is also found that the alumina surface modified by alkylphosphonic acids with longer chain has a higher degree of hydrophobicity and lower coefficient of friction. The best frictional properties are obtained for the system consisting of the alumina surface modified by n-octadecylphosphonic acid and silicon nitride counterpart. Stability tests in different environmental conditions: laboratory, acidic and alkaline solutions were also monitored.

  10. Dynamical stability of the alpha and theta phases of alumina

    DEFF Research Database (Denmark)

    Lodziana, Zbigniew; Parlinski, K.

    2003-01-01

    Using density functional calculations the phonon dispersion relations, phonon density of states, and free energy of theta and alpha phases of alumina are investigated. The temperature dependence of the free energy indicates that entropy contributes to the destabilization of the alpha phase...... cations in alumina, and suggest that some other than entropic mechanism exists, which stabilizes transition aluminas up to 1400 K. The present calculations go beyond the ground state energy calculations [C. Wolverton and K.C. Hass, Phys. Rev. B 63, 24102 (2001)], and give an additional understanding...... of the stability of transition alumina at finite temperatures....

  11. Thermoanalytical study of the formation mechanism of yttria from yttrium acetate

    International Nuclear Information System (INIS)

    Farjas, J.; Camps, J.; Roura, P.; Ricart, S.; Puig, T.; Obradors, X.

    2011-01-01

    Highlights: → Thermal decomposition of yttrium acetate: three endothermic stages. → Intermediates: yttrium hydroxide and carbonate. → Product: cubic yttria (the degree of transformation is at least 99%). → The decomposition does not depend on the oxygen partial pressure. - Abstract: The processes involved in the thermal decomposition of yttrium acetate tetrahydrate, Y(CH 3 COO) 3 .4H 2 O, in air and in an inert atmosphere have been analyzed by thermoanalytical techniques (thermogravimetry, differential thermal analysis and evolved gas analysis) and by the structural characterization (X-ray diffraction, infrared spectroscopy, elemental analysis and scanning electron microscopy) of intermediates and final products. Decomposition of yttrium acetate is an endothermic transformation that takes place in a temperature range between 350 and 900 o C. The evolution of the mass during the decomposition process is not affected by the presence of oxygen. The process is initiated by the rupture of the bond between the metallic cation and the acetate ligand. This initial step (350-450 o C) involves the formation of amorphous yttrium hydroxide and yttrium carbonate and is characterized by a fast mass loss rate. A sudden decrease of the mass loss rate indicates a change in the decomposition kinetics that continues with the decomposition of yttrium hydroxide and yttrium carbonate. The main effect of an oxygen atmosphere is an intense exothermic process due to the combustion of organic species in the gas phase.

  12. Process for recovering yttrium and lanthanides from wet-process phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, J.A.; Weterings, C.A.

    1983-06-28

    Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

  13. Preparation, characterization and thermal behaviour study of double selenates of lanthanides, yttrium and beryllium

    International Nuclear Information System (INIS)

    Ribeiro, C.A.

    1988-01-01

    The lanthanides (III) and yttrium (III) double selenates were studied using common analytical methods, atomic absorption, X-ray diffraction infra-red absorption, thermogravimetry and differential thermal analysis. These compounds were prepared from the mixture of lanthanides (III) and yttrium (III) selenates aqueous solution and basic beryllium selenates aqueous solution, obeying equimolar relation (1:1) to the cation

  14. Investigation of Removal Possibilities of Colloidal Alumina from Aqueous Solution by the Use of Anionic Polyacrylamide

    International Nuclear Information System (INIS)

    Wisniewska, M.; Chibowski, S.; Urban, T.

    2016-01-01

    Purification of drinking and industrial water required usage of high molecular weight polymer to cause flocculation process of dispersed suspension of contaminants. Poly electrolytes, including ionic polyacrylamide are especially appropriate for these purposes, because in this case the suspension stability can be controlled by both steric and electrostatic forces. Thus the influence of solution p H and hydrolysis degree (carboxyl groups content) of anionic polyacrylamide (PAM) on the alumina (Al_2O_3) suspension stability were studied. The turbidimetry was applied for determination of the examined systems stability. The mechanism of suspension stabilization or destabilization in the polymer presence was proposed on the basis of determined parameters: adsorbed amount of PAM, its adsorption layer thickness, linear dimensions of macromolecules in the solution and zeta potential of alumina particles covered with the polyacrylamide layer. The greatest decrease of the alumina suspension stability in the polymer presence in comparison to that without the polymer was obtained at p H 6 after the addition of PAMs with higher molecular weight (i.e. 14 000 0000) and hydrolysis degrees 20 and 30% (efficient neutralization of solid surface charge). In turn, the most unstable alumina system proved to be that prepared at p H 9 containing PAM with the highest molecular weight and the greatest hydrolysis degree (causing the most effective bridging flocculation).

  15. Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avvaru Praveen; Kumar, B. Prem; Kumar, A.B.V. Kiran; Huy, Bui The [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Facile synthesis of palladium nanoparticles on alumina surface. Black-Right-Pointing-Pointer The surface morphology and properties of the nanocrystalline powders were characterized. Black-Right-Pointing-Pointer The catalytic activities of palladium nanoparticles were investigated. - Abstract: The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600 Degree-Sign C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG-DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd{sup 0} while in the atmospheric air indicates the existence pure Pd{sup 0} along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

  16. Interaction of RBa sub 2 Cu sub 3 O sub x (R = Y or Nd) coatings with alumina and zirconia substrates. [YBaCuO; NdBaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C; Parent, L; Champagne, B; Dallaire, S [National Research Council of Canada, Industrial Materials Research Inst., Boucherville, PQ (Canada)

    1989-12-10

    As-deposited YBa{sub 2}Cu{sub 3}O{sub x} coatings by plasma spraying are not superconducting because of their inadequate crystalline structure and low oxygen content. A post-deposition heat treatment in oxygen is required to restore the appropriate superconducting YBa{sub 2}Cu{sub 3}O{sub x} structure. During heat treatment, deterimental reactions between coatings and substrates may occur and lead to the degradation or destruction of the coating superconducting properties. In the present paper, interactions of RBa{sub 2}Cu{sub 3}O{sub x} (R = Y, Nd) coatings with alumina and zirconia substrates are examined. The modifications of the coating electrical properties and microstructure are studied using X-ray diffraction, energy dispersive X-ray analysis and resistivity measurements. Coating degradation is shown to occur by diffusion of the barium atoms out of the coating leading to the formation of Y{sub 2}BaCuO{sub 5} and CuO in yttrium-based coatings, and to the formation of nonstoichiometric Nd{sub 1+y}Ba{sub 2-y}Cu{sub 3}O{sub x} and CuO in neodymium-based coatings. The coating degradation is more important on alumina substrates that on zirconia substrates for both yttrium- and neodymium-based coatings. (orig.).

  17. Yttrium implantation and addition element effects on the oxidation behaviour of reference steels at 973 K

    Energy Technology Data Exchange (ETDEWEB)

    Caudron, E.; Buscail, H.; Cueff, R.; Issartel, C.; El Messki, S.; Perrier, S.; Riffard, F. [Lab. Vellave d' Elaboration et d' Etude des Materiaux, Univ. Blaise Pascal Clermont-Fd 2, Le Puy en Velay (France)

    2004-07-01

    Yttrium implantation effects on reference steels (extra low carbon and low manganese steel) were studied by rutherford backscattering spectrometry (RBS), reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD) and glancing angle X-ray diffraction (GAXRD). Thermogravimetry and in situ X-ray diffraction at 700 C and P{sub O2}=0.04 Pa for 24h were used to determine the yttrium implantation and addition element effects on sample oxidation resistance at high temperatures. This study clearly shows that yttrium implantation and subsequent high temperature oxidation induced the formation of several yttrium mixed oxides which closely depend on the reference steel addition elements. Moreover, these yttrium mixed oxides seem to be responsible for the improved reference steel oxidation resistance at high temperatures. (orig.)

  18. Tattoo removal by Q-switched yttrium aluminium garnet laser

    DEFF Research Database (Denmark)

    Hutton Carlsen, K; Esmann, J; Serup, J

    2017-01-01

    BACKGROUND: Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. OBJECTIVE: To determine clients' satisfaction with tattoo removal. METHODS: One hundred and fifty-four tattoo removal clients who had...... relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate...

  19. Phase composition of yttrium-doped zirconia ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Christoph; Scheinost, Andreas C. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures; Weiss, Stephan [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Ikeda-Ohno, Atsushi [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Chemistry of the F-Elements; Gumeniuk, R. [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Experimentelle Physik

    2017-06-01

    Ceramic material might be an alternative to borosilicate glass for the immobilization of nuclear waste. The crystallinity of ceramic material increases the corrosion resistance over several magnitudes in relation to amorphous glasses. The stability of such ceramics depend on several parameters, among them the crystal phase composition. A reliable quantitative phase analysis is necessary to correlate the macroscopic material properties with structure parameters. We performed a feasibility study based on yttrium-doped zirconia ceramics as analogue for trivalent actinides to ascertain that the nanosized crystal phases in zirconia ceramics can be reliably determined.

  20. Structure-terahertz property relationship in yttrium aluminum garnet ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Steere, D.W.; Clark, B.M.; Sundaram, S.K. [Alfred University, Terahertz and Millimeter Waves Laboratory (T-Lab), Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred, NY (United States); Gaume, R. [Townes Laser Institute and the NanoScience Technology Center, CREOL, The College of Optics and Photonics, Orlando, FL (United States)

    2017-08-15

    Terahertz (THz) transmission measurements on chemically variant yttrium aluminum garnet (YAG) ceramics are described. Chemical compositions and processing parameters were varied to determine the effect of stoichiometry, density, and pore volume distribution on the optical and dielectric properties in the THz frequency regime. Density has the largest effect on properties out of the parameters that were investigated. In addition, a linear correlation between cubic root of real permittivity at 1 THz and average density of these samples is observed. Our results show promise for design and fabrication of advanced optical materials and devices with desired THz properties via controlling density and porosity of the materials. (orig.)

  1. Study on the coextraction of scandium-yttrium-lumogallion complex

    International Nuclear Information System (INIS)

    Okada, T.; Shimoishi, Y.; Miyata, H.; Toei, K.

    1977-01-01

    The coextraction of scandium-yttrium-lumogallion [LMG;4-chloro-6-(2,4-dihydroxyphenylazo)-1-hydroxybenzene-2-sulfonic acid] into diethyl ether has been studied. The acid dissociation constants of LMG, pKsub(a2) and pKsub(a3), were estimated to be 6.24 and 8.05 respectively. The composition of the complex extracted was determined by using the radioisotopes 46 Sc and 90 Y and by spectrophotometry of LMG and the ratio of the components was Sc:Y:LMG = 1:1:3. The coextraction scheme was discussed briefly. (author)

  2. Optical properties of Dy3+ doped yttrium aluminium borate

    International Nuclear Information System (INIS)

    Vazquez, R MartInez; Osellame, R; Marangoni, M; Ramponi, R; Dieguez, E; Ferrari, M; Mattarelli, M

    2004-01-01

    A Dy 3+ doped yttrium aluminium borate (Dy:YAB) crystal has been optically characterized. The refractive indices at seven different wavelengths, ranging from the visible to the near infrared (IR), have been measured and the Sellmeier curves have been calculated. The polarized optical absorption spectra have been obtained at room temperature, and the Judd-Ofelt parameters have been calculated. The lifetime of the upper laser level 4 F 9/2 has been estimated and compared with the experimental value. Evidence of high luminescence quantum efficiency of the 4 F 9/2 state in YAB is provided by measured lifetimes

  3. Kinetic properties of solid yttrium at high temperatures

    International Nuclear Information System (INIS)

    Ivliev, A.D.

    1993-01-01

    Analysis of results of experimental investigation into temperature-diffusivity, specific electroresistance and heat conductivity of yttrium is carried out. Peculiarities of variation of its kinetic characteristics under high temperatures are shown to result from two-band character of energy spectrum of collectivized electrons. In particular, growth of heat conductivity results from reduction of density of heavy electron states under heating. The suggested model describes kinetic characteristics of lutetium, as well. Usage of this model for the rest heavy rare-earth metals enables to make conclusion about reduction of magnetic scattering effcieincy in the rare-earth metals in proportion to approximation to melting temperature

  4. Knee arthroscopy after yttrium or osmic acid injection

    International Nuclear Information System (INIS)

    Guaydier-Souquieres, C.; Beguin, J.; Ollivier, D.; Loyau, G.

    1989-01-01

    This study presents the macroscopic and histologic results of 35 knee arthroscopies performed on patients with rheumatoid arthritis, some months after an yttrium or osmic acid intraarticular injection. The procedure was most often performed after a failure of the injection or a relapse of synovitis. Arthroscopy provides an understanding of the cause of synoviorthesis failure--insufficient action of the product on the synovitis or its poor diffusion, fibri-nonecrotic deposits, or cartilaginous lesions--and may be used both diagnostically and therapeutically

  5. Spectrographic determination of strontium in yttrium-90 solutions

    International Nuclear Information System (INIS)

    Roca, M.; Capdevila, C.

    1970-01-01

    The copper spark method has been used for determining strontium in the concentration range 1-100 g/ml in yttrium-90 solutions containing 0,5 % or thereabouts of ammonium citrate. The influence of the citric acid as well as the ammonium citrate with regard to 2N HCL solutions has been studied: the citric acid enhances the line intensities of strontium. The employment of either barium or lanthanum as reference element compensates for this enhancement. Because of the increase in sensitivity mentioned above, the study of influence of the citric acid has been extended and several impurities usually determined in radioisotope solutions have been considered. (Author) 4 refs

  6. Scattering of polarized protons by yttrium, iron and nickel nuclei

    International Nuclear Information System (INIS)

    Melssen, J.P.M.G.

    1978-01-01

    Results are presented of scattering experiments performed on yttrium and some iron and nickel isotopes with polarized proton beams at energies around 20 MeV. The angular distributions of the differential cross sections and analyzing powers have been measured and comparison of these with predictions from theoretical models has led to information about excited nuclear states like spin, parity and details of the wavefunctions. The DWBA has been mostly used to describe the reaction at the bombarding energies and for the target nuclei investigated. (C.F.)

  7. Childhood acromegaly successfully treated with interstitial irradiation using Yttrium-90

    International Nuclear Information System (INIS)

    Rosenstock, J.; Doyle, F.H.; Mashiter, K.; Joplin, G.F.

    1982-01-01

    A child with a growth hormone producing tumour presented at the age of 4 1/2 years. The onset of the disease was at 18 months of age. Treatment was given with three doses of interstitial irradiation using yttrium-90 implants. There were no local complications from the procedures. Now, 11 years after diagnosis, she is asymptomatic, of normal appearance, and her height and the size of the pituitary fossa are normal. Growth hormone levels are almost normal, thyroid function is intact, and she is maintained on prednisone and sex hormones. (Authors)

  8. Childhood acromegaly successfully treated with interstitial irradiation using Yttrium-90

    Energy Technology Data Exchange (ETDEWEB)

    Rosenstock, J.; Doyle, F.H.; Mashiter, K.; Joplin, G.F. (Royal Postgraduate Medical School, Hammersmith Hospital, London (UK). Dept. of Medicine and Radiology); Hall, R. (Royal Victoria Infirmary, Newcastle upon Tyne (UK))

    1982-01-01

    A child with a growth hormone producing tumour presented at the age of 4 1/2 years. The onset of the disease was at 18 months of age. Treatment was given with three doses of interstitial irradiation using Yttrium-90 implants. There were no local complications from the procedures. Now, 11 years after diagnosis, she is asymptomatic, of normal appearance, and her height and the size of the pituitary fossa are normal. Growth hormone levels are almost normal, thyroid function is intact, and she is maintained on prednisone and sex hormones.

  9. Photometric determination of yttrium in zirconium-containing materials

    International Nuclear Information System (INIS)

    Barbina, T.M.; Polezhaev, Yu.M.

    1984-01-01

    Comparative evaluation of the effect of different ways of eliminating the zirconium interfering effect on the results of yttrium photometric determination with arsenazo 2 in artificial mixtures of Y 2 O 3 and ZrO 2 , containing 5 and 10 mol.% Y 2 O 3 , has been carried out. The effect of Zr is eliminated by means of its precipitation by ammonium solution in the form of hydroxide and using camouflaging with 25% sulfosalicylic acid. Both ways do not provide a correct enough result. The use of non-reagent thermohydrolytic Zr precipitation during the analysis of zirconium-containing materials permits to obtain correct and well-reproducible results

  10. Thiocarbomide coordination compounds of yttrium subgroup rare earth chlorides

    International Nuclear Information System (INIS)

    Sakharova, Yu.G.; Perov, V.N.; Loginov, V.I.

    1978-01-01

    Thiocarbamide coordination compounds of chlorides of elements of the yttrium subgroup 4MeCl 3 x5Cs(NH 2 ) 2 x2OH 2 O (where Me stands for Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) were produced for the first time. The compounds obtained are stable in air, have definite melting points, are highly soluble in methyl and ethyl alcohols, and are unstable in water. They recrystallize from ethyl alcohol without changing their chemical composition. The identity of these compounds was confirmed by X-ray analysis

  11. Laser Surface Treatment of Sintered Alumina

    Science.gov (United States)

    Hagemann, R.; Noelke, C.; Kaierle, S.; Wesling, V.

    Sintered alumina ceramics are used as refractory materials for industrial aluminum furnaces. In this environment the ceramic surface is in permanent contact with molten aluminum resulting in deposition of oxidic material on its surface. Consequently, a lower volume capacity as well as thermal efficiency of the furnaces follows. To reduce oxidic adherence of the ceramic material, two laser-based surface treatment processes were investigated: a powder- based single-step laser cladding and a laser surface remelting. Main objective is to achieve an improved surface quality of the ceramic material considering the industrial requirements as a high process speed.

  12. Cathodoluminescence study of anodic nanochannel alumina

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Q.X. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan)]. E-mail: guoq@cc.saga-u.ac.jp; Hachiya, Y. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Tanaka, T. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Nishio, M. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan); Ogawa, H. [Department of Electrical and Electronic Engineering, Saga University, Honjo-1, Saga, 840-8502 (Japan)

    2006-07-15

    Nanochannel alumina (NCA) templates with highly ordered pore arrays were prepared by anodizing pure aluminum foil in acid solutions. Cathodoluminescence measurements reveal that a blue emission band appears at around 2.8 eV and its energy position depends on measurement temperature and pore size of NCA. The shift of the blue emission band energy with temperature is ascribed to the variations of electron-phonon interactions. X-ray absorption near-edge fine structure results show that the blue emission band shift with pore size is due to the local environment change of atoms in NCA.

  13. Shockless spalling damage of alumina ceramic

    Science.gov (United States)

    Erzar, B.; Buzaud, E.

    2012-05-01

    Ceramic materials are commonly used to build multi-layer armour. However reliable test data is needed to identify correctly models and to be able to perform accurate numerical simulation of the dynamic response of armour systems. In this work, isentropic loading waves have been applied to alumina samples to induce spalling damage. The technique employed allows assessing carefully the strain-rate at failure and the dynamic strength. Moreover, specimens have been recovered and analysed using SEM. In a damaged but unbroken specimen, interactions between cracks has been highlighted illustrating the fragmentation process.

  14. Creep cavitation effects in polycrystalline alumina

    International Nuclear Information System (INIS)

    Porter, J.R.; Blumenthal, W.; Evans, A.G.

    1981-01-01

    Fine grained polycrystalline alumina has been deformed in creep at high temperatures, to examine the evolution of cavities at grain boundaries. Cavities with equilibrium and crack-like morphologies have been observed, distributed nonuniformly throughout the material. The role of these cavities during creep has been described. A transition from equilibrium to crack-like morphology has been observed and correlated with a model based on the influence of the surface to boundary diffusivity ratio and the local tensile stress. The contribution of cavitation to the creep rate and total creep strain has been analyzed and excluded as the principal cause of the observed non-linear creep rate

  15. Investigations on thermoluminescent dosimetry (TLD) with doped alumina ceramics

    International Nuclear Information System (INIS)

    Janas, R.; Huebner, K.

    1976-01-01

    Alumina ceramics doped and burned under various conditions have been investigated with regard to their suitability for thermoluminescent dosimetry. The production of ceramics is described. The properties essential for dosimetric purposes, such as glow curve, energy dose characteristics, fading, recoverability, lower detection limit and energy dependence, are indicated. The advantages and disadvantages of alumina ceramics are compared. (author)

  16. Cavity cutting efficiency of a Bioglass and alumina powder ...

    Indian Academy of Sciences (India)

    1531–1536. c Indian Academy of Sciences. ... conical in shape, whereas cavities produced by alumina and alumina + 45S5 were more ... any other material having good cutting properties is highly .... Saw, Buehler Ltd, IL, USA) at a blade speed of 3500 r.p.m. ... and the machine was run for 1min to remove any residual.

  17. Treatment of chrome plating wastewater (Cr+6) using activated alumina.

    Science.gov (United States)

    Sarkar, Sudipta; Gupta, Anirban

    2003-01-01

    Suitability of activated alumina for removal of hexavalent chromium from electroplating wastewater has been investigated. Activated alumina exhibited good sorption capacity for hexavalent chromium and pH has no pronounced effect on the sorption capacity. Both batch and column adsorption studies have been carried out and an adsorption column design indicated reasonable depth of column for practical application.

  18. Characterization of silane coated hollow sphere alumina-reinforced

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  19. Near net-shape fabrication of alumina glass composites

    NARCIS (Netherlands)

    Zhu, Q.; With, de G.; Dortmans, L.J.M.G.; Feenstra, F.

    2005-01-01

    The purpose of the present study is to fabricate alumina glass composites by melt infiltration with better dimensional control through reducing both the presintering and infiltration temperature. Main efforts were put to develop glasses that are chemically compatible with alumina. After extensive

  20. Synthesis of Gamma-Alumina from Kankara Kaolin as Potential ...

    African Journals Online (AJOL)

    Engr Solomn Gajere

    Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment of ammonium alum prepared from the filtrate of the dealuminated metakaolin was employed to obtain the alumina. Crystalline aluminum sulfate with 39 wt% Al2O3 ...

  1. Synthesis of Nano Crystalline Gamma Alumina from Waste Cans

    Directory of Open Access Journals (Sweden)

    Nada Sadoon Ahmedzeki

    2018-03-01

    Full Text Available In the present study waste aluminium cans were recycled and converted to produce alumina catalyst. These cans contain more than 98% aluminum oxide in their structure and were successfully synthesized to produce nano sized gamma alumina under mild conditions. A comprehensive study was carried out in order to examine the effect of several important parameters on maximum yield of alumina that can be produced. These parameters were reactants mole ratios (1.5, 1.5, 2, 3, 4 and 5, sodium hydroxide concentrations (10, 20, 30, 40, 50 and 55% and weights of aluminum cans (2, 4, 6, 8 and 10 g. The compositions of alumina solution were determined by Atomic absorption spectroscopy (AAS; and maximum yield of alumina solution was 96.3% obtained at 2 mole ratios of reactants, 40% sodium hydroxide concentrations and 10g of aluminum cans respectively. Gamma alumina was acquired by hydrothermal treatment of alumina solution at pH 7 and calcination temperature of 550 ºC. The prepared catalyst was characterized by X-ray diffraction (XRD, N2 adsorption/ desorption isotherms, X-ray fluorescence (XRF and atomic force microscopy (AFM. Results showed good crystallinity of alumina as described by XRD patterns, with surface area of 311.149 m2/g, 0.36 cm3/g pore volume, 5.248 nm pore size and particle size of 68.56 nm respectively.

  2. Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

    Energy Technology Data Exchange (ETDEWEB)

    Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia); Bushev, Pavel [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany)

    2015-09-21

    This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of the phenomenon is demonstrated.

  3. Ordered Nanomaterials Thin Films via Supported Anodized Alumina Templates

    Directory of Open Access Journals (Sweden)

    Mohammed eES-SOUNI

    2014-10-01

    Full Text Available Supported anodized alumina template films with highly ordered porosity are best suited for fabricating large area ordered nanostructures with tunable dimensions and aspect ratios. In this paper we first discuss important issues for the generation of such templates, including required properties of the Al/Ti/Au/Ti thin film heterostructure on a substrate for high quality templates. We then show examples of anisotropic nanostructure films consisting of noble metals using these templates, discuss briefly their optical properties and their applications to molecular detection using surface enhanced Raman spectroscopy. Finally we briefly address the possibility to make nanocomposite films, exemplary shown on a plasmonic-thermochromic nanocomposite of VO2-capped Au-nanorods.

  4. Characterization of the microporous HDPE film with alpha alumina

    International Nuclear Information System (INIS)

    Park, Jong Seok; Sung, Hae Jun; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang

    2010-01-01

    The effects of the addition of the alpha alumina on the properties of the microporous high density polyethylene (HDPE) films were investigated. The particle size and the specific surface area of alpha alumina were 400 nm and 7.3 m 2 g -1 . The HDPE and the alpha alumina were mixed to obtain the precursor film in the twin extruder. The precursor films were uni-axially stretched up to 600% in oven 120 .deg. C and then the stretched HDPE films were irradiated by gamma rays. The pore volume of the microporous HDPE films was increased with an increasing content of the alpha alumina. The mechanical characteristics of the microporous HDPE films were increased with a content of alpha alumina up to 15%, but decreased at 20%. The electrochemical stability of the microporous HDPE film containing alpha alumia was increased with an increased irradiation dose up ti 50 kGy

  5. Thermal shock behavior of rare earth modified alumina ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junlong; Liu, Changxia [Ludong Univ., Yantai (China). School of Transportation

    2017-05-15

    Alumina matrix ceramic composites toughened by AlTiC master alloys, diopside and rare earths were fabricated by hot-pressing and their thermal shock behavior was investigated and compared with that of monolithic alumina. Results showed that the critical thermal shock temperature (ΔT) of monolithic alumina was 400 C. However, it decreased to 300 C for alumina incorporating only AlTiC master alloys, and increased with further addition of diopside and rare earths. Improvement of thermal shock resistance was obtained for alumina ceramic composites containing 9.5 wt.% AlTiC master alloys and 0.5 wt.% rare earth additions, which was mainly attributed to the formation of elongated grains in the composites.

  6. Morphology and transmittance of porous alumina on glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guo Peitao, E-mail: guopeitao@hotmail.com [Wuhan University of Technology. Wuhan (China); Xia Zhilin [Wuhan University of Technology. Wuhan (China); Key Laboratory of Low Dimensional Materials and Application Technology, Xiangtan University, Ministry of Education, Xiangtan (China); Xue Yiyu [Wuhan University of Technology. Wuhan (China); Huang Caihua [China Three Gorges University, Yichang (China); Zhao Lixin [Wuhan University of Technology. Wuhan (China)

    2011-02-01

    The porous optical film has higher threshold of laser-induced damage than densified films, for the study of mechanism of laser-induced damage of porous optical film with ordered pore structure. Porous anodic alumina (PAA) film with high transmittance on glass substrate has been prepared. Aluminum film was deposited on glass substrate by means of resistance and electron beam heat (EBH) evaporation. Porous alumina was prepared in oxalic acid solution under different anodizing conditions. At normal incidence, the optical transmittance spectrum over 300-1000 nm spectra region was obtained by spectrophotometer. SEM was introduced to analysis the morphology of the porous alumina film. The pore aperture increased with the increase of anodizing voltage, which resulted in a rapid decrease of the pore concentration and the optical thickness of porous alumina film. Damage morphology of porous alumina film is found to be typically defects initiated, and the defect is the pore presented on the film.

  7. Characterization and sintering of niobium-ATR alumina

    International Nuclear Information System (INIS)

    Sibuya, N.H.; Iwasaki, H.; Suzuki, C.K.; Pinatti, D.G.

    1987-01-01

    In the niobium aluminothermy a slag is produced, composed mostly of alumina and other compounds such as niobium oxide and silica. The phase composition of this ATR alumina was characterized by X-ray powder diffractometry, and afterwards this alumina was subjected to leaching processes. It was noticed that the original content of 70% α-alumina in slag rose to 95% after the calcination. ATR alumina (leached and calcined, and without any treatment) was used to make pressed bodies which were fired in air at 1200 to 1400 0 C for 1 to 10,5 hours; and in vacuum at 1550 to 1800$0C for 2 hours. Characterization was done by density measurements, X-ray diffractometry and ultrasonic analysis. Ultrasonic analysis of some vacuum fired bodies showed londitudinal velocities close to the value found in literature. Correlation of several techniques measurements disclosed the niobium oxide interference in sintering. (Author) [pt

  8. The mineralogy of bauxite for producing smelter-grade alumina

    Science.gov (United States)

    Authier-Martin, M.; Forte, G.; Ostap, S.; See, J.

    2001-12-01

    Aluminum-producing companies rely on low-cost, high-purity, smelter-grade alumina (aluminum oxide), and alumina production utilizes the bulk of bauxites mined world-wide. The mineralogy of the bauxites has a significant impact on the operation of the Bayer process for alumina production. Typically, the Bayer process produces smelter-grade alumina of 99.5% Al2O3, starting from bauxite containing 30% to 60% Al2O3. The main objective of the Bayer process is to extract the maximum amount of aluminum from the bauxite at as high an aluminate concentration in solution as possible, while limiting any troublesome side reactions. Only with a better understanding of the chemistry of the mineral species and a strict control of the operating/processing conditions can the Bayer process produce efficiently, a low cost, high-quality alumina with minimum detrimental environmental impact.

  9. Properties of Transition Metal Doped Alumina

    Science.gov (United States)

    Nykwest, Erik; Limmer, Krista; Brennan, Ray; Blair, Victoria; Ramprasad, Rampi

    Crystallographic texture can have profound effects on the properties of a material. One method of texturing is through the application of an external magnetic field during processing. While this method works with highly magnetic systems, doping is required to couple non-magnetic systems with the external field. Experiments have shown that low concentrations of rare earth (RE) dopants in alumina powders have enabled this kind of texturing. The magnetic properties of RE elements are directly related to their f orbital, which can have as many as 7 unpaired electrons. Since d-block elements can have as many as 5 unpaired electrons the effects of substitutional doping of 3d transition metals (TM) for Al in alpha (stable) and theta (metastable) alumina on the local structure and magnetic properties, in addition to the energetic cost, have been calculated by performing first-principles calculations based on density functional theory. This study has led to the development of general guidelines for the magnetic moment distribution at and around the dopant atom, and the dependence of this distribution on the dopant atom type and its coordination environment. It is anticipated that these findings can aid in the selection of suitable dopants help to guide parallel experimental efforts. This project was supported in part by an internship at the Army Research Laboratory, administered by the Oak Ridge Institute for Science and Education, along with a grant of computer time from the DoD High Performance Computing Modernization Program.

  10. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Boyi [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Zhu, Yong, E-mail: y.zhu@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Chen, Youping; Song, Han; Huang, Pengcheng [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Dao, Dzung Viet [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia)

    2017-06-15

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  11. Yttrium ion implantation on the surface properties of magnesium

    International Nuclear Information System (INIS)

    Wang, X.M.; Zeng, X.Q.; Wu, G.S.; Yao, S.S.

    2006-01-01

    Owing to their excellent physical and mechanical properties, magnesium and its alloys are receiving more attention. However, their application has been limited to the high reactivity and the poor corrosion resistance. The aim of the study was to investigate the beneficial effects of ion-implanted yttrium using a MEVVA ion implanter on the surface properties of pure magnesium. Isothermal oxidation tests in pure O 2 at 673 and 773 K up to 90 min indicated that the oxidation resistance of magnesium had been significantly improved. Surface morphology of the oxide scale was analyzed using scanning electron microscope (SEM). Auger electron spectroscopy (AES) and X-ray diffraction (XRD) analyses indicated that the implanted layer was mainly composed of MgO and Y 2 O 3 , and the implanted layer with a duplex structure could decrease the inward diffusion of oxygen and reduce the outward diffusion of Mg 2+ , which led to improving the oxidation resistance of magnesium. Potentiodynamic polarization curves were used to evaluate the corrosion resistance of the implanted magnesium. The results show yttrium implantation could enhance the corrosion resistance of implanted magnesium compared with that of pure magnesium

  12. Hydrogen sensor based on palladium-yttrium alloy nanosheet

    International Nuclear Information System (INIS)

    Wang, Boyi; Zhu, Yong; Chen, Youping; Song, Han; Huang, Pengcheng; Dao, Dzung Viet

    2017-01-01

    This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

  13. Effects of hepatic arterial yttrium 90 glass microspheres in dogs.

    Science.gov (United States)

    Wollner, I; Knutsen, C; Smith, P; Prieskorn, D; Chrisp, C; Andrews, J; Juni, J; Warber, S; Klevering, J; Crudup, J

    1988-04-01

    A 22-micron glass microsphere called TheraSphere (Theragenics Corp., Atlanta, GA) has been developed in which yttrium 89 oxide is incorporated into the glass matrix and is activated by neutron bombardment to form the beta-emitting isotope yttrium 90 (Y 90) before using the spheres as radiotherapeutic vehicles. The injection of up to 12 times (on a liver weight basis) the anticipated human dose of nonradioactive TheraSphere into the hepatic arteries of dogs was well tolerated and produced clinically silent alterations within centrolobular areas. The hepatic arterial (HA) injection of radioactive TheraSphere also produced portal changes similar to those observed in humans after external beam therapy. While the extent of damage increased with the delivered dose, radiation exposures in excess of 30,000 cGy did not cause total hepatic necrosis and were compatible with survival. No microspheres distributed to the bone marrow and absolutely no myelosuppression was encountered in any animal. Proposed hepatic exposures to humans of 5000 to 10,000 cGy by means of these microspheres, therefore, would appear to be feasible and tolerable. Radiotherapeutic microsphere administration preceded by regional infusion of a radiosensitizing agent and/or immediately following the redistribution of blood flow toward intrahepatic tumor by vasoactive agents can potentially yield a synergistic, highly selective attack on tumors confined to the liver.

  14. MCrAlY bond coat with enhanced Yttrium layer

    Science.gov (United States)

    Jablonski, Paul D; Hawk, Jeffrey A

    2015-04-21

    One or more embodiments relates to an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y--Al oxides, providing advantage in the maintainability of the Yttrium reservoir within the MCrAlY bulk. The MCrAlY bond coat may be fabricated through application of a Y.sub.2O.sub.3 paste to an MCrAlY material, followed by heating in a non-oxidizing environment.

  15. Effect of vanadium and yttrium doping on BSCCO superconductors

    International Nuclear Information System (INIS)

    Mohamed, S.B.; Halim, S.A.; Azhan, H.; Sidek, H.A.A; Tee, T.W.; Hassan, Z.A.

    1999-01-01

    The effect of vanadium and yttrium doping on the superconductivity is investigated. The doping was done on the calcium site ranging from x=0.00-0.10. The temperature dependence of electrical resistance and AC susceptibility measurements were made on these samples. The zero resistance for vanadium doped samples varied from 107 K (x = 0.00) to 68.5K (x = 0.10), whereas for yttrium doped samples it varied from 107 K (x = 0.00) to 54K (x 0.10). The volume fraction of the 2223 phase for both dopalit decreases witli increasing doping concentration. The nature of the temperature derivative of the resistance curves indicates the presence of a superconducting transition between grains coupled by weak links. The AC susceptibility data show enrichment of the volume fraction of the low Tc phase at higher compositions. The presence of low Tc phase (∼70 K) is visible in the susceptibility data. X-ray diffraction confirms the presence of mixed phases in the samples. (author)

  16. radio embolization of yttrium 90 glass microspheres in treatment of hepatocellular carcinoma

    International Nuclear Information System (INIS)

    El Fouly, A.H.A.

    2010-01-01

    Hepatocellular carcinoma (HCC) is a common cancer that typically occurs in the setting of cirrhosis and chronic hepatitis virus infections. HCC is considered currently as global problem; its incidence is expected to increase dramatically by the next few decades. More than 90 % of the accidentally diagnosed patients have non resectable tumor. Portal vein thrombosis, diffuse multifocal liver infiltration and large tumor burden are considered to be a great obstacle in front of the modern lines of treatment, even with Child A liver cirrhosis. Transarterial intrahepatic application of Yttrium-90 glass microspheres may allow effective local ablative treatment of patients with intrahepatic advanced hepatocellular carcinoma (HCC) with or without portal vein thrombosis. The aim of this open-label phase II study was to validate evidence on the safety and efficacy of this treatment in an European cohort of patients with locally advanced HCC such as (large tumor burden, multifocal distribution, portal vein thrombosis). And to assess the response rate according to different approved response assessment guidelines (WHO, RECIST and EASL). Patients and Methods Starting from November 2006 till March 2009, one hundred and eight advanced unresectable HCC patients with and without portal vein thrombosis were included in this prospective study. Yttrium-90 microspheres radiotherapy was performed in a lobar fashion through the right or left hepatic artery. In bilobar disease, right and left liver lobe were treated with 4-6 weeks intervals in between. Response rate was assessed according to different international response assessment criteria (WHO, RECIST and EASL) with sequential computed tomography scans till the last clinical visit or death. The safety of this technique was assessed according to the Common Toxicity Criteria version 3

  17. The reactive element effect of yttrium and yttrium silicon on high temperature oxidation of NiCrAl coating

    Science.gov (United States)

    Ramandhany, S.; Sugiarti, E.; Desiati, R. D.; Martides, E.; Junianto, E.; Prawara, B.; Sukarto, A.; Tjahjono, A.

    2018-03-01

    The microstructure formed on the bond coat affects the oxidation resistance, particularly the formation of a protective oxide layer. The adhesion of bond coat and TGO increased significantly by addition of reactive element. In the present work, the effect of yttrium and yttrium silicon as reactive element (RE) on NiCrAl coating was investigated. The NiCrAl (without RE) and NiCrAlX (X:Y or YSi) bond coating were deposited on Hastelloy C-276 substrate by High Velocity Oxygen Fuel (HVOF) method. Isothermal oxidation was carried out at 1000 °C for 100 hours. The results showed that the addition of RE could prevent the breakaway oxidation. Therefore, the coating with reactive element were more protective against high temperature oxidation. Furthermore, the oxidation rate of NiCrAlY coating was lower than NiCrAlYSi coating with the total mass change was ±2.394 mg/cm2 after 100 hours of oxidation. The thickness of oxide scale was approximately 1.18 μm consisting of duplex oxide scale of spinel NiCr2O4 in outer scale and protective α-Al2O3 in inner scale.

  18. Evaluation of technological properties of alumina refractory systems-zirconia and zirconia-silica-alumina

    International Nuclear Information System (INIS)

    Marinho, A.R.O.; Carvalho, T.U.S.; Fagury Neto, E.; Rabelo, A.A.

    2014-01-01

    Alumina-zirconia refractories are noted for being products of excellent cost-effective, however, zirconia may limit its use due to decreasing resistance to thermal shock. This study aims to evaluate these refractories with the addition of microsilica, which can greatly improve their properties. Were used the following starting materials: calcined alumina, zirconia (stabilized and monoclinic) in amounts of 2%, 4% and 6% by weight, plus microsilica (5%w.). The powders were milled together with binder and lubricant for conformation bodies by uniaxial pressing. The samples were dried, calcined and sintered at 1400 °C/2h were characterized using the methods of Archimedes, and scanning electron microscopy (SEM), chemical analysis using energy dispersive X-ray (EDS), and mechanical flexural strength tests at room temperature. Formulations with the presence of microsilica showed satisfactory results and optimized properties. (author)

  19. Microstructural evolution of alumina-zirconia nanocomposites; Evolucao microestrutural de nanocompositos alumina-zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Ojaimi, C.L.; Chinelatto, A.S.A.; Chinelatto, A.L. [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil); Pallone, E.M.J.A., E-mail: christianelago@yahoo.com.br [Universidade de Sao Paulo (USP), Pirassununga, Sao Paulo, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos

    2012-07-01

    Ceramic materials have limited use due to their brittleness. The inclusion of nanosized particles in a ceramic matrix, which are called nanocomposites, and ceramic processing control by controlling the grain size and densification can aid in obtaining ceramic products of greater strength and toughness. Studies showed that the zirconia nano inclusions in the matrix of alumina favors an increase in mechanical properties by inhibiting the grain growth of the matrix and not by the mechanism of the transformation toughening phase of zirconia. In this work, the microstructural evolution of alumina nanocomposites containing 15% by volume of nanometric zirconia was studied. From the results it was possible to understand the sintering process of these nanocomposites. (author)

  20. Microstructural evaluation of alumina-niobium and alumina- niobium-zircon ceramics for ballistic application

    International Nuclear Information System (INIS)

    Mota, Juliana Machado da; Lopes, Cristina Moniz Araujo; Melo, Francisco Lourenco Cristovao de

    2009-01-01

    This study aimed to evaluate the microstructural of Alumina- Niobium and Alumina- Niobium-Zircon ceramics. Samples with 3.5 x 4.5 x 34 mm dimensions were prepared by uniaxial pressure (50 MPa) followed by isostatic pressure (300 MPa). The samples were sintered at 1500 ° C for 1 hour. The ceramics obtained were characterized by scanning electron microscopy (SEM) and X-ray diffraction, to evaluate the phases and microstructures. In order to analyze the microstructure, by SEM the samples were prepared using two techniques: heat treatment (1350 ° C for 5 minutes) and thermochemical treatment (500 ° C for 8 minutes in a solution of NaOH and KOH) on polished and fractured surfaces. The results showed that despite differences between the two etchings, both were effective to analyze the microstructure. (author)

  1. Dissolution kinetics for alumina in cryolite melts. Distribution of alumina in the electrolyte of industrial aluminium cells

    Energy Technology Data Exchange (ETDEWEB)

    Kobbeltvedt, Ove

    1997-12-31

    This thesis contributes to the understanding of which factors determine the rate of dissolution of alumina added to the bath in alumina reduction cells. Knowing this may help reduce the occurrences of operation interruptions and thus make it possible to produce aluminium using less energy. When alumina powder was added to a stirred cryolite melt, the alumina dissolved in two distinct main stages. In the first stage, the dissolution rate was very high, which reflects dissolution of single alumina grains that are being dispersed in the bath upon addition. In the second stage, lumps of alumina infiltrated with bath dissolved at a rate considerably slower than that of the first stage. The formation of these alumina agglomerates is the most important contributor to slow dissolution. The parameters varied in the experiments were convection, batch size, and temperature of the bath and of the added alumina. Increased gas stirring of the bath speeded up dissolution in both stages but the size of the batch was of little significance. Increasing the bath temperature had no effect in the first stage but speeded up dissolution considerably in the second stage. Compared to adding alumina at room temperature, preheating it to a high temperature (600 {sup o}C) increased the dissolution rate in the first stage while preheating to lower temperatures (100-300 {sup o}C) decreased the dissolution rate. In the second stage, preheating slowed the dissolution. The two latter phenomena of reduced dissolution rates are ascribed to the removal of moisture from the alumina upon preheating. The bath flow and the distribution of alumina in the bath were measured in four different types of cells. It was found that if a certain asymmetry of the magnetic field traverse to the cell was present, due to the presence of risers, then loops of high velocity bath flow occurred near the short ends of the cell. Thus, alumina added near the short ends is effectively transferred away from the feeding

  2. Neutron activation determination of oxygen in ceramic materials on the basis of yttrium, barium and copper

    International Nuclear Information System (INIS)

    Goldshtein, M.M.; Yudelevich, I.G.

    1991-01-01

    A procedure of determining oxygen in superconducting materials on the basis of yttrium, barium and copper oxides with the application of 14 MeV-neutron activation was developed. The method is based on determining the relation between oxygen and yttrium in the compounds investigated. In order to minimize systematic errors, expressions accounting for spectrometer dead time under conditions of varying component activity are proposed. The procedure ensures determination of the relation between oxygen and yttrium with a relative error of 0.4% with NAA using a neutron generator. (author) 4 refs.; 1 fig

  3. Study of behaviour of lanthanum- and yttrium electrodes in chloride melts

    International Nuclear Information System (INIS)

    Shkol'nikov, S.I.; Tolypin, E.S.; Yur'ev, B.P.

    1984-01-01

    A study was made on the lanthanum- and yttrium behaviour in a mixture of molten potassium- and sodium chlorides at various temperatures. It is shown that the lanthanum- and yttrium behaviour in KCl-NaCl melt is similar to the behaviour of other metals. Their corrosion rate is much higher as compared to other metals and it grows rapidly with increasing melt temperature. The temperature growth by 200 deg C results in an increase in the corrosion rate almost by an order. The potentials of lanthanum- and yttrium electrodes at the instant they are immersed in the melt have more negative values than the potentials of alkali metals under similar conditions

  4. Effect of yttrium chromite doping on its resistance to high-temperature salt and gas corrosions

    International Nuclear Information System (INIS)

    Oryshich, I.V.; Poryadchenko, N.E.; Rakitskij, A.N.; Bega, N.D.

    1996-01-01

    Effect of yttrium chromite doping with 2-4 group metal oxides on the corrosion resistance in the air at 1300 C during 5 hours and in sodium chloride and sulfate melts at 900 C during 20 hours is investigated. A notable increase of corrosion resistance is achieved under complex doping with zirconium and magnesium oxides in a quantity, close to solubility in yttrium oxide and solubility by aluminium oxide. Doping with calcium and strontium oxides in the quantities, dose to solubility in yttrium oxide does not produce any notable effect, and at higher concentrations it reduces the corrosion resistance in media indicated. Refs. 8, refs. 2, tabs. 1

  5. Mechanical behavior of alumina and alumina-feldspar based ceramics in an acetic acid (4%) environment

    International Nuclear Information System (INIS)

    Stumpf, Aisha S.G.; Bergmann, Carlos P.; Vicenzi, Juliane; Fetter, Rebecca; Mundstock, Karina S.

    2009-01-01

    This study investigates the mechanical properties of alumina-feldspar based ceramics when exposed to an aggressive environment (acetic acid 4%). Alumina ceramics containing different concentrations of feldspar (0%, 1%, 5%, 10%, or 40%) were sintered at either 1300, 1600, or 1700 o C. Flaws (of width 0%, 30%, or 50%) were introduced into the specimens using a saw. Half of these ceramic bodies were exposed to acetic acid. Their flexural strength, K IC , and porosity were measured and the fractured samples were evaluated using scanning electronic- and optical microscopy. It was found that in the ceramic bodies sintered at 1600 o C, feldspar content up to 10% improved flexural strength and K IC, and reduced porosities. Generally, it was found that acetic acid had a weakening effect on the flexural strength of samples sintered at 1700 o C but a beneficial effect on K IC of ceramics sintered at 1600 o C. It was concluded that alumina-based ceramics with feldspar content up to 10% and sintered at higher temperatures would perform better in an aggressive environment similar to oral cavity.

  6. A Technological Comparison of Six Processes for the Production of Reduction-Grade Alumina from Non-Bauxitic Raw Materials

    Science.gov (United States)

    Bengtson, K. B.

    The U. S. Bureau of Mines, by means of a contract with Kaiser Engineers and with Kaiser Aluminum & Chemical Corporation as a subcontractor, has sponsored a technological and an economic evaluation of six candidate processes for the manufacture of alumina from certain U. S. raw materials other than bauxite. This paper describes each process. Flow diagrams and the total energy requirement for each process are included. Important characteristics affecting the economics of producing alumina by each process are discussed, and some presently unsolved technical problems are identified. The extraction of alumina from clay via hydrochloric acid with iron separation by solvent extraction, and the crystallization of intermediate AlCl3·6H2O through the introduction of HCl gas into the pregnant mother liquor, appears to be technically feasible and the most attractive of the six raw material/process combinations.

  7. Effect of heat treatment on the structure of incorporated oxalate species and photoluminescent properties of porous alumina films formed in oxalic acid

    Science.gov (United States)

    Vrublevsky, I.; Jagminas, A.; Hemeltjen, S.; Goedel, W. A.

    2008-09-01

    The present work focuses on the use of IR spectroscopy and photoluminescence spectral measurements for studying the treatment temperature effect on the compositional and luminescent properties of oxalic acid alumina films. In line with the recent researches we have also found that heat treatment of porous alumina films formed in oxalic acid leads to considerable changes in their photoluminescence properties: upon annealing the intensity of photoluminescence (PL) increases reaching a maximum at the temperature of around 500 °C and then decreases. IR spectra of as-grown and heat-treated films have proved that PL emission in the anodic alumina films is related with the state of 'structural' oxalate species incorporated in the oxide lattice. These results allowed us to conclude that PL behavior of oxalic acid alumina films can be explained through the concept of variations in the bonding molecular orbitals of incorporated oxalate species including σ- and π-bonds.

  8. Master sintering curves of two different alumina powder compacts

    Directory of Open Access Journals (Sweden)

    Vaclav Pouchly

    2009-12-01

    Full Text Available Concept of Master Sintering Curve is a strong tool for optimizing sintering schedule. The sintering behaviour can be predicted, and sintering activation energy can be calculated with the help of few dilatometric measurements. In this paper an automatic procedure was used to calculate Master Sintering Curves of two different alumina compacts. The sintering activation energies were determined as 640 kJ/mol for alumina with particle size of 240 nm, respective 770 kJ/mol for alumina with particle size of 110 nm. The possibility to predict sintering behaviour with the help of Master Sintering Curve was verified.

  9. Effect of alumina on the dissolution rate of glasses

    International Nuclear Information System (INIS)

    Palavit, G.; Montagne, L.

    1997-01-01

    Small alumina addition to silicate glasses improves their chemical durability, but a large amount of alumina can also be beneficial to obtain a high dissolution rate. This paper describes the effect of Al 3+ on the early stage of glass alteration, in relation with its coordination in the glass and also with the reactions involved (hydrolysis and ionic exchange). We describe briefly nuclear magnetic resonance tools available to characterize the aluminum environments in the glasses. The rote of alumina on the dissolution rate of phosphate glasses is also discussed in order to show that the effect of Al 3+ is dependant upon the nature of the glass matrix. (author)

  10. Activated alumina preparation and characterization: The review on recent advancement

    Science.gov (United States)

    Rabia, A. R.; Ibrahim, A. H.; Zulkepli, N. N.

    2018-03-01

    Aluminum and aluminum based material are significant industrial materials synthesis because of their abandonment, low weight and high-quality corrosion resistance. The most advances in aluminum processing are the ability to synthesize it's under suitable chemical composition and conditions, a porous structure can be formed on the surface. Activated alumina particles (AAP) synthesized by the electrochemically process from aluminum have gained serious attention, inexpensive material that can be employed for water filtration due to its active surface. Thus, the paper present a review study based on recent progress and advances in synthesizing activated alumina, various techniques currently being used in preparing activated alumina and its characteristics are studied and summarized

  11. Nanoporous alumina as templates for multifunctional applications

    Science.gov (United States)

    Sousa, C. T.; Leitao, D. C.; Proenca, M. P.; Ventura, J.; Pereira, A. M.; Araujo, J. P.

    2014-09-01

    Due to its manufacturing and size tailoring ease, porous anodic alumina (PAA) templates are an elegant physical-chemical nanopatterning approach and an emergent alternative to more sophisticated and expensive methods currently used in nanofabrication. In this review, we will describe the ground work on the fabrication methods of PAA membranes and PAA-based nanostructures. We will present the specificities of the electrochemical growth processes of multifunctional nanomaterials with diversified shapes (e.g., nanowires and nanotubes), and the fabrication techniques used to grow ordered nanohole arrays. We will then focus on the fabrication, properties and applications of magnetic nanostructures grown on PAA and illustrate their dependence on internal (diameter, interpore distance, length, composition) and external (temperature and applied magnetic field intensity and direction) parameters. Finally, the most outstanding experimental findings on PAA-grown nanostructures and their trends for technological applications (sensors, energy harvesting, metamaterials, and biotechnology) will be addressed.

  12. Plasma sprayed alumina-titania coatings

    International Nuclear Information System (INIS)

    Steeper, T.J.; Rotolico, A.J.; Nerz, J.E.; Riggs, W.L. II; Varacalle, D.J. Jr.; Wilson, G.C.

    1992-01-01

    This paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. attempts are made to correlate the features of the coatings with the changes in operating parameters

  13. Alumina strength degradation in the elastic regime

    International Nuclear Information System (INIS)

    Furnish, Michael D.; Chhabildas, Lalit C.

    1998-01-01

    Measurements of Kanel et al. [1991] have suggested that deviatoric stresses in glasses shocked to nearly the Hugoniot Elastic Limit (HEL) relax over a time span of microseconds after initial loading. 'Failure' (damage) waves have been inferred on the basis of these measurements using time-resolved manganin normal and transverse stress gauges. Additional experiments on glass by other researchers, using time-resolved gauges, high-speed photography and spall strength determinations have also lead to the same conclusions. In the present study we have conducted transmitted-wave experiments on high-quality Coors AD995 alumina shocked to roughly 5 and 7 GPa (just below or at the HEL). The material is subsequently reshocked to just above its elastic limit. Results of these experiments do show some evidence of strength degradation in the elastic regime

  14. Compositional characterization of atomic layer deposited alumina

    Energy Technology Data Exchange (ETDEWEB)

    Philip, Anu; Thomas, Subin; Kumar, K. Rajeev [Department of Instrumentation, Cochin University of Science and Technology, Cochin-22, Kerala (India)

    2014-01-28

    As the microelectronic industry demands feature size in the order of few and sub nanometer regime, the film composition and other film properties become critical issues and ALD has emerged as the choice of industry. Aluminum oxide is a material with wide applications in electronic and optoelectronic devices and protective and ion barrier layers. Al{sub 2}O{sub 3} is an excellent dielectric because of its large band gap (8.7eV), large band offsets with silicon. We have deposited thin layers of alumina on silicon wafer (p-type) for gate dielectric applications by ALD technique and compositional characterizations of the deposited thin films were done using EDS, XPS and FTIR spectra.

  15. Compositional characterization of atomic layer deposited alumina

    International Nuclear Information System (INIS)

    Philip, Anu; Thomas, Subin; Kumar, K. Rajeev

    2014-01-01

    As the microelectronic industry demands feature size in the order of few and sub nanometer regime, the film composition and other film properties become critical issues and ALD has emerged as the choice of industry. Aluminum oxide is a material with wide applications in electronic and optoelectronic devices and protective and ion barrier layers. Al 2 O 3 is an excellent dielectric because of its large band gap (8.7eV), large band offsets with silicon. We have deposited thin layers of alumina on silicon wafer (p-type) for gate dielectric applications by ALD technique and compositional characterizations of the deposited thin films were done using EDS, XPS and FTIR spectra

  16. Rheological properties of alumina injection feedstocks

    Directory of Open Access Journals (Sweden)

    Vivian Alexandra Krauss

    2005-06-01

    Full Text Available The rheological behavior of alumina molding feedstocks containing polyethylene glycol (PEG, polyvinylbutyral (PVB and stearic acid (SA and having different powder loads were analyzed using a capillary rheometer. Some of the feedstocks showed a pseudoplastic behavior of n < 0, which can lead to the appearance of weld lines on molded parts. Their viscosity also displayed a strong dependence on the shear rate. The slip phenomenon, which can cause an unsteady front flow, was also observed. The results indicate that the feedstock containing a lower powder load displayed the best rheological behavior. The 55 vol. % powder loaded feedstock presented the best rheological behavior, thus appearing to be more suitable than the formulation containing a vol. 59% powder load, which attained viscosities exceeding 10³ Pa.s at low shear rates, indicating its unsuitability for injection molding.

  17. Two steps sintering alumina doped with niobia

    International Nuclear Information System (INIS)

    Gomes, L.B.; Hatzfeld, J.; Heck, M.; Pokorny, A.; Bergmann, C.P.

    2014-01-01

    In this work, high surface area commercial alumina was doped with niobia and sintered in two steps in order to obtain dense materials with lower processing temperatures. The powders were milled and uniaxially pressed (200 MPa). The first step of sintering took place at 1100°C for 3, 6, 9 and 12 hours, followed by the second step at 1350°C for 3 hours. The relative density, porosity and water absorption of the samples were determined by the Archimedes method. The crystalline phases were analyzed by X-ray Diffraction (XRD) and the morphology of the samples after sintering, evaluated by Scanning Electron Microscopy (SEM). The results indicate that the use of niobia combined with the two steps sintering promotes an increase in the density of the material, even at lower sintering temperatures. (author)

  18. Characterization of alumina suspensions by electroacoustics

    Energy Technology Data Exchange (ETDEWEB)

    Galassi, C.; Roncari, E.; Greenwood, R.; Piancastelli, A. [CNR, Faenza (Italy). Research Inst. for Ceramics Technology

    1997-12-31

    Using the acoustophoresis technique three different dispersants were selected to investigate the effect of the volume fraction of the suspension on the minimum amount of dispersant required to give the maximum zeta potential. No effect was detected over a volume fraction range 0.11 to 0.35. The acoustosizer was used to screen many dispersants for alumina in a relatively short time. From the viewpoint that the most stable suspensions are those with the greatest zeta potentials, then the following dispersants can be recommended: Reotan LA (0.25 mg/m{sup 2}) Dolapix CA (0.20 mg/m{sup 2}) and Dolapix PC33 (0.30 mg/m{sup 2}). Vanisperse and Borresperse are poor. Polyacrylic acid and polymethacrylic acid were better than some commercially available products. (orig.) 2 refs.

  19. The local strength of microscopic alumina reinforcements

    International Nuclear Information System (INIS)

    Žagar, Goran; Pejchal, Václav; Mueller, Martin G.; Rossoll, Andreas; Cantoni, Marco; Mortensen, Andreas

    2015-01-01

    We measure, using an adaptation of a method designed for ceramic ball bearings, the local strength of a brittle second phase that serves to reinforce a metal. The method uses focused ion beam milling and a nanoindentation device, and is free of artifacts commonly present in micromachined specimens. It is demonstrated on Nextel 610™ nanocrystalline alumina fibers embedded in an aluminum matrix composite. Results reveal a size effect that does not follow, across size scales, usual Weibull statistics: the fiber strength distribution differs between measurements at the microscale and macroscopic tensile testing. This implies that, in micromechanical analysis of multiphase materials, highly localized events such as the propagation of internal damage require input data that must be measured at the same, local, microscale as the event; the present work opens a path to this end.

  20. Fabrication of Terahertz Wave Resonators with Alumina Diamond Photonic Crystals for Frequency Amplification in Water Solvents

    International Nuclear Information System (INIS)

    Ohta, N; Niki, T; Kirihara, S

    2011-01-01

    Terahertz wave resonators composed of alumina photonic crystals with diamond lattice structures were designed and fabricated by using micro stereolithography. These three dimensional periodic structures can reflect perfectly electromagnetic waves through Bragg diffraction. A micro glass cell including water solutions was put between the photonic crystals as a novel resonance sensor with terahertz frequency range. The localized and amplified waves in the resonators were measured by a spectroscopy, and visualized by theoretical simulations.

  1. A study of the bending resistance of implant-supported reinforced alumina and machined zirconia abutments and copies.

    Science.gov (United States)

    Sundh, Anders; Sjögren, Göran

    2008-05-01

    The purpose of the present study was to evaluate the bending resistance of implant-supported CAD/CAM-processed restorations made out of zirconia or manually shaped made out of reinforced alumina. Units of abutments and copies made of (i) a prefabricated hot isostatic pressed (HIPed) yttrium oxide partially-stabilized zirconia (Y-TZP) (Denzir), (ii) a prefabricated densely-sintered magnesia partially stabilized zirconia (Mg-PSZ) (Denzir-M) or, copies made of (iii) a prefabricated partially-sintered, porous reinforced alumina ceramic (RN synOcta-In-Ceram) were subjected to static loading perpendicularly at the long axis. The abutments were attached to either stainless steel analogs or titanium implant fixtures. The Y-TZP and Mg-PSZ copies were bonded onto the ceramic abutments with a dual-cured resin composite (Rely-X Unicem). Units of titanium abutment attached to a titanium implant fixtures were used as reference. The units comprising Denzir abutments as delivered (pstainless steel analogs exhibited significantly higher bending resistance than the control. The heat-treated Denzir copies bonded to the heat-treated Denzir M abutments attached to titanium implant fixtures and the In-Ceram specimens attached to stainless steel analogs showed significantly (pstainless steel analogs. No statistically significant (p>0.05) differences were seen among the other groups studied. All the ceramic abutments and copies exhibited values that were equal or superior to that of the control and exceeded the reported value, up to 300 N, for maximum incisal bite forces. To assess the clinical behavior long-term clinical studies should be conducted.

  2. Glass transition temperature of PMMA/modified alumina nanocomposite: Molecular dynamic study

    OpenAIRE

    Mohammadi, Maryam; Davoodi, Jamal; Javanbakht, Mahdi; Rezaei, Hamidreza

    2017-01-01

    In this study, the effect of alumina and modified alumina nanoparticles in a PMMA/alumina nanocomposite was investigated. To attain this goal, the glass transition behavior of poly methyl methacrylate (PMMA), PMMA/alumina and PMMA/hydroxylated alumina nanocomposites were investigated by molecular dynamic simulations (MD). All the MD simulations were performed using the Materials Studio 6.0 software package of Accelrys. To obtain the glass transition temperature, the variation of density vs. t...

  3. Calorimetric investigation of an yttrium-dysprosium spin glass

    International Nuclear Information System (INIS)

    Wenger, L.E.

    1978-01-01

    In an effort to compare the spin glass characteristics of yttrium--rare earth alloys with those of the noble-metal spin glasses, the susceptibility and heat capacity of Y/sub 0.98/Dy/sub 0.02/ have been measured in the temperature range 2.5--40 K. The low-field ac susceptibility measurement shows the characteristic cusp-like peak at 7.64 K. The magnetic specific heat of the same sample shows a peak at 7.0 K and may be qualitatively described as a semi-cusp. The magnetic entropy change from absolute zero to 7 K is approximately 0.52 of cR ln(2J+1). These results are qualitatively different than previous calorimetric results on the archetypal spin glasses, AuFe and CuMn, where rounded maxima are observed at temperatures above the spin glass transition temperatures

  4. RBS Characterization of Yttrium Iron Garnet Thin Films

    International Nuclear Information System (INIS)

    Roumie, M; Abdel samad, B.

    2008-01-01

    Magnetic materials such as yttrium iron garnet (YIG) are of great importance for its magneto-optic properties and for their potential applications in the domain of optical telecommunications. The deposition of thin films of YIG, on quartz or GGG (gadolinium gallium garnet) substrate, was performed using radio frequency non reactive magnetron sputtering, followed by high temperature annealing which is needed to enhance the crystallinity of the layers. Rutherford backscattering spectrometry RBS was used to determine the thickness and stoichiometry of the performed layers in order to investigate correlations between growth conditions and the quality of the final material. RBS measurements showed the influence of the deposition time and the temperature substrate on the film growth and its stoichiometry. (author)

  5. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Kaminaga, Kenichi; Sei, Ryosuke [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hayashi, Kouichi [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Happo, Naohisa [School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Tajiri, Hiroo [Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, Sayo 679-5198 (Japan); Oka, Daichi; Fukumura, Tomoteru, E-mail: tomoteru.fukumura.e4@tohoku.ac.jp [Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan)

    2016-03-21

    Rare earth oxides are usually widegap insulators like Y{sub 2}O{sub 3} with closed shell trivalent rare earth ions. In this study, solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y{sup 2+} (4d{sup 1}) was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO has been recognized as gaseous phase in previous studies. In contrast with Y{sub 2}O{sub 3}, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10{sup −1} to 10{sup 3} Ω{sup −1 }cm{sup −1} was attributed to the presence of oxygen vacancies serving as electron donor. Weak antilocalization behavior observed in magnetoresistance indicated significant role of spin-orbit coupling as a manifestation of 4d electron carrier.

  6. Tunable negative index metamaterial using yttrium iron garnet

    International Nuclear Information System (INIS)

    He, Yongxue; He, Peng; Dae Yoon, Soack; Parimi, P.V.; Rachford, F.J.; Harris, V.G.; Vittoria, C.

    2007-01-01

    A magnetic field tunable, broadband, low-loss, negative refractive index metamaterial is fabricated using yttrium iron garnet (YIG) and a periodic array of copper wires. The tunability is demonstrated from 18 to 23 GHz under an applied magnetic field with a figure of merit of 4.2 GHz/kOe. The tuning bandwidth is measured to be 5 GHz compared to 0.9 GHz for fixed field. We measure a minimum insertion loss of 4 dB (or 5.7 dB/cm) at 22.3 GHz. The measured negative refractive index bandwidth is 0.9 GHz compared to 0.5 GHz calculated by the transfer function matrix theory and 1 GHz calculated by finite element simulation

  7. {alpha}-particle induced reactions on yttrium and terbium

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S.; Kumar, B.B. [School of Studies in Physics, Vikram University, Ujjain-456010 (India); Rashid, M.H. [Variable Energy Cyclotron Center, 1/AF, Bidhan Nagar, Calcutta (India); Chintalapudi, S.N. [Inter-University Consortium for DAE Facilities, 3/LB, Bidhan Nagar, Calcutta (India)

    1997-05-01

    The stacked foil activation technique has been employed for the investigation of {alpha}-particle induced reactions on the target elements yttrium and terbium up to 50 MeV. Six excitation functions for the ({alpha},xn) type of reactions were studied using high-resolution HPGe {gamma}-ray spectroscopy. A comparison with Blann{close_quote}s geometric dependent hybrid model has been made using the initial exciton number n{sub 0}=4(4p0h) and n{sub 0}=5(5p0h). A broad general agreement is observed between the experimental results and theoretical predictions with an initial exciton number n{sub 0}=4(4p0h). {copyright} {ital 1997} {ital The American Physical Society}

  8. α-particle induced reactions on yttrium and terbium

    International Nuclear Information System (INIS)

    Mukherjee, S.; Kumar, B.B.; Rashid, M.H.; Chintalapudi, S.N.

    1997-01-01

    The stacked foil activation technique has been employed for the investigation of α-particle induced reactions on the target elements yttrium and terbium up to 50 MeV. Six excitation functions for the (α,xn) type of reactions were studied using high-resolution HPGe γ-ray spectroscopy. A comparison with Blann close-quote s geometric dependent hybrid model has been made using the initial exciton number n 0 =4(4p0h) and n 0 =5(5p0h). A broad general agreement is observed between the experimental results and theoretical predictions with an initial exciton number n 0 =4(4p0h). copyright 1997 The American Physical Society

  9. Thermal conductivity of yttrium iron garnet at low temperatures

    International Nuclear Information System (INIS)

    Joshi, Y.P.; Sing, D.P.

    1979-01-01

    An analysis of the low-temperature thermal conductivity of yttrium iron garnet is presented giving consideration to the fact that in a conventional conductivity experiment the magnon temperature gradient inside a magnetic insulator need not be necessarily equal to the phonon temperature gradient. Consequently the effective conductivity can be less than the algebraic sum of the phonon and magnon intrinsic conductivities, depending on the magnon-phonon thermal relaxation rate. This relaxation rate has been distinguished from the individual phonon and magnon relaxation rates and an expression is derived for it. Theoretical calculations of the effective conductivity are found to be in good agreement with experimental results. The contribution of magnons to the effective conductivity is observed to be small at all temperatures below the conductivity maximum. (author)

  10. Yttrium orthoferrite powder obtained by the mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Zorica Ž.

    2017-01-01

    Full Text Available Yttrium orthoferrite (YFeO3 powder was prepared by a mechanochemical synthesis from a mixture of Y2O3 and α-Fe2O3 powders in a planetary ball mill for 2.5 h. The obtained YFeO3 powder sample was characterized by X-ray diffraction (XRD, Raman and infrared spectroscopy. The average crystallite size calculated by the Scherrer equation was 12 nm. The Mössbauer spectroscopy at room temperature confirms the superparamagnetic character of YFeO3 orthoferrite sample. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45003, Grant no. III 45015, Grant no. III 45018

  11. Nanoscale nonlinear effects in Erbium-implanted Yttrium Orthosilicate

    Energy Technology Data Exchange (ETDEWEB)

    Kukharchyk, Nadezhda, E-mail: nadezhda.kukharchyk@physik.uni-saarland.de [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany); Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Shvarkov, Stepan [Optoelektronische Materialien und Bauelemente, Universität Paderborn, D-33098 Padeborn (Germany); Probst, Sebastian [Quantronics group, Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette cedex (France); Xia, Kangwei [3. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart (Germany); Becker, Hans-Werner [RUBION, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Pal, Shovon [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); AG THz Spectroscopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Markmann, Sergej [AG THz Spectroscopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Kolesov, Roman; Siyushev, Petr; Wrachtrup, Jörg [3. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart (Germany); Ludwig, Arne [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Ustinov, Alexey V. [Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe (Germany); Wieck, Andreas D. [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); and others

    2016-09-15

    Doping of substrates at desired locations is a key technology for spin-based quantum memory devices. Focused ion beam implantation is well-suited for this task due to its high spacial resolution. In this work, we investigate ion-beam implanted Erbium ensembles in Yttrium Orthosilicate crystals by means of confocal photoluminescence spectroscopy. The sample temperature and the post-implantation annealing step strongly reverberate in the properties of the implanted ions. We find that hot implantation leads to a higher activation rate of the ions. At high enough fluences, the relation between the fluence and final concentration of ions becomes non-linear. Two models are developed explaining the observed behavior.

  12. Successful treatment of Cushing's disease using yttrium-90 rods

    International Nuclear Information System (INIS)

    White, M.C.; Doyle, F.H.; Mashiter, K.; Joplin, G.F.

    1982-01-01

    Interstitial irradiation using yttrium-90 ( 90 Y) rods implanted by needle into the pituitary gland was used as primary treatment in 16 patients with pituitary dependent Cushing's disease. Clinical and biochemical remission was observed within three to six months in 13 and in the remaining three after a supplementary implant. There was no perioperative morbidity. Follow-up from the time of definitive operation ranged from six to 123 months (mean 39). No recurrence has been observed. The return of a normal diurnal cortisol rhythm has been observed in 10/12 patients studied after remission. Some form of long-term pituitary hormone replacement therapy was required in only the six patients who had received the largest irradiation dose. Implantation of 90 Y is safe and effective treatment for patients with Cushing's disease, comparing favourably with selective trans-sphenoidal pituitary surgery. (author)

  13. Photocatalysis of Yttrium Doped BaTiO3 Nanofibres Synthesized by Electrospinning

    Directory of Open Access Journals (Sweden)

    Zhenjiang Shen

    2015-01-01

    Full Text Available Yttrium doped barium titanate (BT nanofibres (NFs with significant photocatalytic effect were successfully synthesized by electrospinning. Considering the necessary factors for semiconductor photocatalysts, a well-designed procedure was carried out to produce yttrium doped BT (BYT NFs. In contrast to BYT ceramics powders and BT NFs, BYT NFs with pure perovskite phase showed much enhanced performance of photocatalysis. The surface modification in electrospinning and subsequent annealing, the surface spreading of transition metal yttrium, and the narrowed band gap energy in yttrium doping were all contributed to the final novel photocatalytic effect. This work provides a direct and efficient route to obtain doped NFs, which has a wide range of potential applications in areas based on complex compounds with specific surface and special doping effect.

  14. Polymer Derived Yttrium Silicate Ablative TPS Materials for Next-Generation Exploration Missions, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Through the proposed NASA SBIR program, NanoSonic will optimize its HybridSil® derived yttrium silicates to serve as next-generation reinforcement for carbon and...

  15. Synthesis of yttrium oxide nanoparticles via a facile microplasma-assisted process

    NARCIS (Netherlands)

    Lin, Liangliang; Starostin, Sergey A.; Li, Sirui; Khan, Saif A.; Hessel, Volker

    2018-01-01

    Plasma electrochemistry is an emerging technique for nanomaterial synthesis. The present study reports the preparation of yttrium oxide nanoparticles via a simple, environmentally benign, microplasma-assisted process operated in pin-to-liquid configuration under ambient atmospheric conditions using

  16. Cathodoluminescence properties of yttrium aluminum garnet doped with Eu2+ and Eu3+ ions

    International Nuclear Information System (INIS)

    Trofimov, A. N.; Petrova, M. A.; Zamoryanskaya, M. V.

    2007-01-01

    Yttrium aluminium garnet (YAG) doped with Eu 2+ and Eu 3+ ions is very interesting as a phosphor for conversion of light-emitting diode light for white light sources. The europium ion occupies the structural position of yttrium in yttrium aluminium garnet and has valence state Eu 3+ . Our sample was doped with Zr 4+ , which is why some of the europium ions had valence state Eu 2+ . As a rule, luminescence of Eu 3+ ions is observed in the orange and red range of spectrum. The luminescence of Eu 2+ in yttrium aluminum garnet is characterized by an intensive broad band with maximum of intensity at about 560 nm (green color). In this work, we studied the intensity and decay time dependences on europium concentration, and the influence of excitation power density on the cathodoluminescence of the sample. The most interesting result is the change of visible cathodoluminescence color in dependence on the density of the exciting power

  17. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

    International Nuclear Information System (INIS)

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd; Vegliò, Francesco

    2013-01-01

    Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2 2 full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H 2 O 2 concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2 2 full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na 2 S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%

  18. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Innocenzi, Valentina, E-mail: valentina.innocenzi1@univaq.it [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); De Michelis, Ida; Ferella, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy); Beolchini, Francesca [Department of Marine Sciences, Polytechnic Institute of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Kopacek, Bernd [SAT, Austrian Society for Systems Engineering and Automation, Gurkasse 43/2, A-1140 Vienna (Austria); Vegliò, Francesco [Department of Industrial Engineering and Information and Economy, University of L’Aquila, Via Giovanni Gronchi n.18, Nucleo Ind.le di Pile, 67100 L’Aquila (Italy)

    2013-11-15

    Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2{sup 2} full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H{sub 2}O{sub 2} concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2{sup 2} full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na{sub 2}S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%.

  19. Alumina-on-Polyethylene Bearing Surfaces in Total Hip Arthroplasty.

    Science.gov (United States)

    Jung, Yup Lee; Kim, Shin-Yoon

    2010-02-11

    The long-term durability of polyethylene lining total hip arthroplasty (THA) mainly depends on periprosthetic osteolysis due to wear particles, especially in young active patients. In hip simulator study, reports revealed significant wear reduction of the alumina ceramic-on-polyethylene articulation of THA compared with metal-on-polyethylene bearing surfaces. However, medium to long-term clinical studies of THA using the alumina ceramic-on-polyethylene are few and the reported wear rate of this articulation is variable. We reviewed the advantages and disadvantages of ceramicon- polyethylene articulation in THA, hip simulator study and retrieval study for polyethylene wear, in vivo clinical results of THA using alumina ceramic-on-polyethylene bearing surfaces in the literature, and new trial alumina ceramic-onhighly cross linked polyethylene bearing surfaces.

  20. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  1. Significance of structure–property relationship in alumina based ...

    Indian Academy of Sciences (India)

    Unknown

    adverse environmental conditions and mechanical vibra- tions. Most ceramic ... However, even alumina insulators manufactured (for use in 25 kV railway traction ..... early showed plastic deformation and large cracks in and around the indents.

  2. Ceramic joining through reactive wetting of alumina with calcium ...

    Indian Academy of Sciences (India)

    phase analysis of the fractured joint surface clearly indicate reactive wetting of the alumina ceramics. This wetting enhances ... ally considered oxide materials for many applications. .... three cases but is more pronounced in the case of C12A7.

  3. Characterization of the Uptake of Nitrogen Oxides on Alumina Adsorbents

    National Research Council Canada - National Science Library

    Pocengal, David

    1999-01-01

    ...) to quantify nitrate and nitrite (NOx) in aqueous solutions that contained NOx exposed alumina and to correlate the quantities of these surface NOx species with the quantity of gaseous NOx sorbed...

  4. Surface chloride salt formation on Space Shuttle exhaust alumina

    Science.gov (United States)

    Cofer, W. R., III; Pellett, G. L.; Sebacher, D. I.; Wakelyn, N. T.

    1984-01-01

    Aluminum oxide samples from the exhaust of Space Shuttle launches STS-1, STS-4, STS-5, and STS-6 were collected from surfaces on or around the launch pad complex and chemically analyzed. The results indicate that the particulate solid-propellant rocket motor (SRM) alumina was heavily chlorided. Concentrations of water-soluble aluminum (III) ion were large, suggesting that the surface of the SRM alumina particles was rendered soluble by prior reactions with HCl and H2O in the SRM exhaust cloud. These results suggest that Space Shuttle exhaust alumina particles are good sites for nucleation and condensation of atmospheric water. Laboratory experiments conducted at 220 C suggest that partial surface chloriding of alumina may occur in hot Space Shuttle exhaust plumes.

  5. Processing and characterization of alumina/LAS bioceramics for ...

    Indian Academy of Sciences (India)

    Administrator

    dental applications. M GUEDES1,4,*, V .... Alumina/LAS bioceramics for dental applications. 697 strength ... assessment. ... indentation load (N) and c is the median length (m) of the ... mixtures show two distinct modes, reflecting both the.

  6. Synthesis of α-Alumina (Corundum) and its Application

    International Nuclear Information System (INIS)

    Nay Thwe Kyi; Kyaw Myo Naing; Tin Tin Aye; Nyunt Wynn

    2005-09-01

    This paper described the preparation of aluminium isopropoxide from aluminium sheet at different heating times.Aluminium sheet is found to have a reaction with absolute isopropyl alcohol and mercury (II) chloride as a catalyst under nitrogen atmosphere. Aluminium isopropoxide was characterized by NMR, XRD and IR. Aluminium isopropoxide serves as a molecular precursor to derive pure alumina gel by hydrolysis under both homogeneous and heterogeneous conditions. Pyrolysis to this alumina gel transforms it into -aluminia (corundum) at 1200'C. The phase transformation during pyrolysis was characterized by XRD, SEM and TEM. The alumina (corundum) has porous crystalline nature with high surface aera, which may be used as efficient adsorbent packing material in coloumn chromatography for the seperation of vitamin A from the leaves. -alumina can be also used in catalysis

  7. Effect of chemical composition and alumina content on structure and ...

    Indian Academy of Sciences (India)

    porcelain types (Morrell 1985; Vazquez and Mejia Velasquez. 1998). By increasing ... Orlova et al found that, in alumina porcelains, opti- mum mechanical ... of high mobility of ions, acceptable electrical performance may be achieved with ...

  8. Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ.

    Science.gov (United States)

    Firlar, Emre; Çınar, Simge; Kashyap, Sanjay; Akinc, Mufit; Prozorov, Tanya

    2015-05-21

    Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles.

  9. Poly(Butylene Terephthalate Based Composites Containing Alumina Whiskers: Influence of Filler Functionalization on Dielectric Properties

    Directory of Open Access Journals (Sweden)

    Pietro Russo

    2014-01-01

    Full Text Available Poly(butylene terephthalate (PBT is one of the most widely used semicrystalline thermoplastics polyester because of its superior thermal and mechanical properties, high dimensional stability and excellent processability. In this research PBT-based nanocomposites, including various amounts (up to 10 wt% of commercial alumina whiskers, have been prepared by using a Brabender internal chamber mixer and analysed in terms of morphological features and dielectric properties. Specific attention has been focused on the effect of the filler functionalization considering 3-glycidoxy propylmethoxysilane (GPS or 3-methacryloxypropyltrimethoxysilane (MPS as coupling agents. Tests, performed on compounds filled with neat and functionalized alumina whiskers, show a clear dependence of relative dielectric permittivity εr, invariance of dissipation factor (tgδ, and a sensible increase of volume electrical resistivity (ρv with the filler’s content and are encouraging for a future introduction of such composites in many electrical applications.

  10. Synthesis of yttrium silicate luminescent materials by sol-gel method

    International Nuclear Information System (INIS)

    Arkhipov, D.V.; Vasina, O.Yu.; Popovich, N.V.; Galaktionov, S.S.; Soshchin, N.P.

    1996-01-01

    Several yttrium-silicate composition with Y 2 O 3 content within 44-56% have been synthesized. it is ascertained that employment of sol-gel technique permits preparation of luminescent materials on yttrium silicate basis, which compare favourably with bath-produced specimens. The influence of phase composition of sol-gel phosphors on basic performance indices: intensity and luminescence spectrum, has been analyzed

  11. Radiation protection data sheets for the use of Strontium 90-Yttrium 90 in unsealed sources

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    This radiation protection data sheet is intended for supervisors and staff in the different medical, hospital, pharmaceutical, university and industrial laboratories and departments where Strontium 90-Yttrium 90 is handled, and also for all those involved in risk prevention in this field. It provides essential data on radiation protection measures during the use of Strontium 90-Yttrium 90 in unsealed sources: physical characteristics, risk assessment, administrative procedures, recommendations, regulations and bibliography

  12. Temperature effect on elastic properties of yttrium ferrite garnet Y3Fe5O12

    International Nuclear Information System (INIS)

    Burenkov, Yu.A.; Nikanorov, S.P.

    2002-01-01

    One studied temperature dependence of all independent elastic constants describing comprehensively elastic anisotropy of yttrium ferrite garnet within temperature wide range covering T c . One measured the Young modules for [100] and [110] crystallographic directions and the module of shift for [100] direction of specially pure single crystal of yttrium ferrite garnet within 20-600 deg C temperature range. One analyzed behavior of elastic modules and of elastic anisotropy factor near the critical temperature of magnetic phase transition [ru

  13. Quantitative description of yttrium aluminate ceramic composition by means of Er+3 microluminescence spectrum

    Science.gov (United States)

    Videla, F. A.; Tejerina, M. R.; Moreira-Osorio, L.; Conconi, M. S.; Orzi, D. J. O.; Flores, T.; Ponce, L. V.; Bilmes, G. M.; Torchia, G. A.

    2018-05-01

    The composition of erbium-doped yttrium aluminate ceramics was analyzed by means of confocal luminescence spectroscopy, EDX, and X-ray diffraction. A well-defined linear correlation was found between a proposed estimator computed from the luminescence spectrum and the proportion of ceramic phases coexisting in different samples. This result shows the feasibility of using erbium luminescence spectroscopy to perform a quantitative determination of different phases of yttrium aluminates within a micrometric region in nanograined ceramics.

  14. Alumina-on-Polyethylene Bearing Surfaces in Total Hip Arthroplasty

    OpenAIRE

    Jung, Yup Lee; Kim, Shin-Yoon

    2010-01-01

    The long-term durability of polyethylene lining total hip arthroplasty (THA) mainly depends on periprosthetic osteolysis due to wear particles, especially in young active patients. In hip simulator study, reports revealed significant wear reduction of the alumina ceramic-on-polyethylene articulation of THA compared with metal-on-polyethylene bearing surfaces. However, medium to long-term clinical studies of THA using the alumina ceramic-on-polyethylene are few and the reported wear rate of th...

  15. Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

    OpenAIRE

    Akiya, Shunta; Kikuchi, Tatsuya; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2016-01-01

    Self-ordered periodic porous alumina with an undiscovered cell diameter was fabricated via electrochemical anodizing in a new electrolyte, phosphonic acid (H3PO3). High-purity aluminum plates were anodized in phosphonic acid solution under various operating conditions of voltage, temperature, concentration, and anodizing time. Phosphonic acid anodizing at 150-180 V caused the self-ordering behavior of porous alumina, and an ideal honeycomb nanostructure measuring 370-440 nm in cell diameter w...

  16. Interface chemistry of nanostructured materials: ion adsorption on mesoporous alumina.

    Science.gov (United States)

    Wang, Yifeng; Bryan, Charles; Xu, Huifang; Pohl, Phil; Yang, Yi; Brinker, C Jeffrey

    2002-10-01

    This paper presents a part of our work on understanding the effect of nanoscale pore space confinement on ion sorption by mesoporous materials. Acid-base titration experiments were performed on both mesoporous alumina and alumina particles under various ionic strengths. The point of zero charge (PZC) for mesoporous alumina was measured to be approximately 9.1, similar to that for nonmesoporous alumina materials, indicating that nanoscale pore space confinement does not have a significant effect on the PZC of pore surfaces. However, for a given pH deviation from the PZC, (pH-PZC), the surface charge per mass on mesoporous alumina was as much as 45 times higher than that on alumina particles. This difference cannot be fully explained by the surface area difference between the two materials. Our titration data have demonstrated that nanoscale confinement has a significant effect, most likely via the overlap of the electric double layer (EDL), on ion sorption onto mesopore surfaces. This effect cannot be adequately modeled by existing surface complexation models, which were developed mostly for an unconfined solid-water interface. Our titration data have also indicated that the rate of ion uptake by mesoporous alumina is relatively slow, probably due to diffusion into mesopores, and complete equilibration for sorption could take 4-5 min. A molecular simulation using a density functional theory was performed to calculate ion adsorption coefficients as a function of pore size. The calculation has shown that as pore size is reduced to nanoscales (<10 nm), the adsorption coefficients of ions can vary by more than two orders of magnitude relative to those for unconfined interfaces. The prediction is supported by our experimental data on Zn sorption onto mesoporous alumina. Owing to their unique surface chemistry, mesoporous materials can potentially be used as effective ion adsorbents for separation processes and environmental cleanup.

  17. Structural and magnetic properties of yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrites prepared by microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Akhtar, Majid Niaz, E-mail: majidniazakhtar@ciitlahore.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Bakar Sulong, Abu [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, G.C. University, Lahore, Pakistan" f Department of Mechanical Engineering, COMSATS Institute of Information Technology Sahiwal Pakistan (Pakistan); Raza, M.R. [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Mechanical Engineering, COMSATS Institute of Information Technology Sahiwal (Pakistan); Raza, R.; Saleem, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Kashif, M. [Department of Physics, Govt. College University Faisalabad (Pakistan)

    2016-03-01

    Yttrium iron garnet (YIG) and yttrium aluminum iron garnet (YAIG) nanoferrite samples were synthesized by microemulsion method. The effect of sintering was examined by heating the samples at 900, 1000, and 1100 °C. The YIG and YAIG samples were then characterized using X-ray diffraction and field-emission scanning electron microscopy. Static and dynamic magnetic properties were measured by evaluating initial permeability, Q factor, and vibrating sample magnetometry properties of YIG and YAIG samples. YIG samples sintered at 1100 °C showed higher initial permeability and Q factor compared with YAIG samples. However, hysteresis loops also showed variations in the saturation magnetization, remanence, and coercivity of YIG and YAIG samples sintered at 900, 1000, and 1100 °C. The observed magnetic parameter such as saturation magnetization, coercivity and initial permeability are strongly affected by increasing temperature. The saturation magnetization and coercivity of YIG and YAIG nanoferrites were found in the range 11.56–19.92 emu/g and 7.30–87.70 Oe respectively. Furthermore, the decreasing trends in the static and magnetic properties of YAIG samples may be due to the introduction of Al ions in the YIG crystal lattice. Thus, YIG and YAIG sintered at 1100 °C can be used for wide-ranging frequency applications. - Highlights: • Static and dynamic magnetic properties of YIG and YAIG nanoferrites were determined. • Saturation magnetization, Q and initial permeability increased in YIG nanoferites. • Possible use of these nanoferrites for sensing and switching applications.

  18. N-m-nitrocinnamoylphenylhydroxyl-amine as reagent for amperometric determination of yttrium

    International Nuclear Information System (INIS)

    Oliferenko, G.L.; Gallaj, Z.A.; Sheina, N.M.; Shvedene, N.V.

    1983-01-01

    Possibility of using organic reagent of unsaturated N-arylsubstituted derivatives class of hydroxamic acids N-m-nitrocinnamoyl phenylhydroxylamire (NCPHA) for amperometric titration of yttrium using indication of e.t.p. by current of reagent oxidation on graphite electrode is investigated. Metal and the NCPHA form difficultly soluble complex with ratio of yttrium to the NCPHA, which is equal to 1:3. Buffer mixtures of 0.1MNH 3 +0.1MCH 3 COOH composis tion with pH 6.3-7.5 are optimal background solutions for amperometric titration of yttrium. The proposed method permits to determine 10-600 μkg of yttrium in the volume of 10 ml. Effect of the series of strange elements on titration of yttrium with NCPHA (Ca, Mg, Mn (2), Al, CU (2), Fe (3) REE and others) is studied. The developed method is used for yttrium determination in luminophores of Casub(n)-- Ysub(m)Fsub(z)xMn(2) (1-10%) composition

  19. The behaviour of selected yttrium containing bioactive glass microspheres in simulated body environments.

    Science.gov (United States)

    Cacaina, D; Ylänen, H; Simon, S; Hupa, M

    2008-03-01

    The study aims at the manufacture and investigation of biodegradable glass microspheres incorporated with yttrium potentially useful for radionuclide therapy of cancer. The glass microspheres in the SiO2-Na2O-P2O5-CaO-K2O-MgO system containing yttrium were prepared by conventional melting and flame spheroidization. The behaviour of the yttrium silicate glass microspheres was investigated under in vitro conditions using simulated body fluid (SBF) and Tris buffer solution (TBS), for different periods of time, according to half-life time of the Y-90. The local structure of the glasses and the effect of yttrium on the biodegradability process were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy and Back Scattered Electron Imaging of Scanning Electron Microscopy (BEI-SEM) equipped with Energy Dispersive X-ray (EDX) analysis. UV-VIS spectrometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for analyzing the release behaviour of silica and yttrium in the two used solutions. The results indicate that the addition of yttrium to a bioactive glass increases its structural stability which therefore, induced a different behaviour of the glasses in simulated body environments.

  20. Size-dependent cytotoxicity of yttrium oxide nanoparticles on primary osteoblasts in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Guoqiang, E-mail: zhougq1982@163.com; Li, Yunfei; Ma, Yanyan; Liu, Zhu; Cao, Lili; Wang, Da; Liu, Sudan; Xu, Wenshi; Wang, Wenying [Hebei University, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Environmental Science (China)

    2016-05-15

    Yttrium oxide nanoparticles are an excellent host material for the rare earth metals and have high luminescence efficiency providing a potential application in photodynamic therapy and biological imaging. In this study, the effects of yttrium oxide nanoparticles with four different sizes were investigated using primary osteoblasts in vitro. The results demonstrated that the cytotoxicity generated by yttrium oxide nanoparticles depended on the particle size, and smaller particles possessed higher toxicological effects. For the purpose to elucidate the relationship between reactive oxygen species generation and cell damage, cytomembrane integrity, intracellular reactive oxygen species level, mitochondrial membrane potential, cell apoptosis rate, and activity of caspase-3 in cells were then measured. Increased reactive oxygen species level was also observed in a size-dependent way. Thus, our data demonstrated that exposure to yttrium oxide nanoparticles resulted in a size-dependent cytotoxicity in cultured primary osteoblasts, and reactive oxygen species generation should be one possible damage pathway for the toxicological effects produced by yttrium oxide particles. The results may provide useful information for more rational applications of yttrium oxide nanoparticles in the future.

  1. Alumina Concentration Detection Based on the Kernel Extreme Learning Machine.

    Science.gov (United States)

    Zhang, Sen; Zhang, Tao; Yin, Yixin; Xiao, Wendong

    2017-09-01

    The concentration of alumina in the electrolyte is of great significance during the production of aluminum. The amount of the alumina concentration may lead to unbalanced material distribution and low production efficiency and affect the stability of the aluminum reduction cell and current efficiency. The existing methods cannot meet the needs for online measurement because industrial aluminum electrolysis has the characteristics of high temperature, strong magnetic field, coupled parameters, and high nonlinearity. Currently, there are no sensors or equipment that can detect the alumina concentration on line. Most companies acquire the alumina concentration from the electrolyte samples which are analyzed through an X-ray fluorescence spectrometer. To solve the problem, the paper proposes a soft sensing model based on a kernel extreme learning machine algorithm that takes the kernel function into the extreme learning machine. K-fold cross validation is used to estimate the generalization error. The proposed soft sensing algorithm can detect alumina concentration by the electrical signals such as voltages and currents of the anode rods. The predicted results show that the proposed approach can give more accurate estimations of alumina concentration with faster learning speed compared with the other methods such as the basic ELM, BP, and SVM.

  2. Antimicrobial Properties of Chitosan-Alumina/f-MWCNT Nano composites

    International Nuclear Information System (INIS)

    Masheane, M.; Nthunya, L.; Malinga, S.; Masheane, M.; Nthunya, L.; Nxumalo, E.; Mhlanga, S.; Barnard, T.

    2016-01-01

    Antimicrobial chitosan-alumina/functionalized-multi walled carbon nano tube (f-MWCNT) nano composites were prepared by a simple phase inversion method. Scanning electron microscopy (SEM) analyses showed the change in the internal morphology of the composites and energy dispersive spectroscopy (EDS) confirmed the presence of alumina and f-MWCNTs in the chitosan polymer matrix. Fourier transform infrared (FTIR) spectroscopy showed the appearance of new functional groups from both alumina and f-MWCNTs, and thermogravimetric analysis (TGA) revealed that the addition of alumina and f-MWCNTs improved the thermal stability of the chitosan polymer. The presence of alumina and f-MWCNTs in the polymer matrix was found to improve the thermal stability and reduced the solubility of chitosan polymer. The prepared chitosan-alumina/f-MWCNT nano composites showed inhibition of twelve strains of bacterial strains that were tested. Thus, the nano composites show a potential for use as a biocides in water treatment for the removal of bacteria at different environmental conditions.

  3. Superhydrophobic surfaces fabricated by surface modification of alumina particles

    Science.gov (United States)

    Richard, Edna; Aruna, S. T.; Basu, Bharathibai J.

    2012-10-01

    The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.

  4. Effects of Etching Time and NaOH Concentration on the Production of Alumina Nanowires Using Porous Anodic Alumina Template

    Science.gov (United States)

    Sadeghpour-Motlagh, M.; Mokhtari-Zonouzi, K.; Aghajani, H.; Kakroudi, M. Ghassemi

    2014-06-01

    In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific.

  5. Influence of additives on the stability of the phases of alumina; Influencia de aditivos na estabilidade das fases da alumina

    Energy Technology Data Exchange (ETDEWEB)

    Rosario, D.C.C.; Gouvea, D., E-mail: deisedorosario@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Metalurgica e de Materiais. Laboratorio de Processos Ceramicos

    2011-07-01

    Problems with the stability of gamma alumina in catalytic reactions have been solved with the inclusion of additives during the synthesis of alumina. These additives stabilize the temperature of phase transition allowing the use of metastable alumina at high temperatures, but the mechanisms of action of additives are not well defined. It is known that each family of additive or additives behaves in different ways for this stabilization. This work aimed to study the performance of MgO and ZrO{sub 2}, respectively at different concentrations in alumina synthesized via Pechini. The samples were analyzed by DSC, X-ray diffraction, measurement of specific surface area by BET analysis, and infrared analysis. The results showed an increase in transition temperature for both additives, and a different changes for specific surface area, showing that MgO and ZrO{sub 2} work on improving the stability but with distinct mechanisms. (author)

  6. Studies for the yttrium determination by activation analysis, in the presence of lanthanides. Application of the substoichiometric technique

    International Nuclear Information System (INIS)

    Silva, D.I.T. da.

    1978-01-01

    Some methods using extraction chromatography for the separation of yttrium from the lanthanide elements were applied. The separation of yttrium was studied, using di-(2 ethylhexyl) orthophosphoric acid as stationary phase, Kieselguhr as support and HNO 3 of concentration between 4,5 and 5,0 N as the mobile phase. In these conditions, about 50% of pure yttrium was obtained. The substoichiometric technique was applied to the determination of yttrium. The elements was partially complexed and the Y 3 + ions were separated from the complex (EDTA-Y) - by means of a cationic resin. The sensitivity, precision and accuracy which can be expected in the analytical results were studied. The possibility of the analysis of a sample containing 1 part per million of yttrium with an error just above 8% was demonstrated. It was also shown that, admitting an error of 10%, it is possible to determine 60 parts per billion of yttrium [pt

  7. Study of decomposition kinetics of volatile β-diketonates of yttrium, barium and copper in flow reactor

    International Nuclear Information System (INIS)

    Devyatykh, G.G.; Gavrishchuk, E.M.; Gibin, A.M.; Dadanov, A.Yu.; Dzyubenko, N.G.; Kaul', A.R.; Nichiporuk, R.V.; Snezhko, N.T.; Ul'yanov, A.A.

    1990-01-01

    Heterogeneous oxidative decomposition of adduct of yttrium acetylacetonate with o-phenanthroline, copper acetylacetonate and barium dipivaloylmethanate in a flow-type reactor was carried out. The basic kinetic characteristics of chemical precipitation processes of films of yttrium, copper and barium oxides, which are components of high-temperature superconductors, were obtained. The values of activation energy of precipitation process of yttrium, copper and barium oxides constituted 76±10, 108±15, 81±12 (t 600 deg C) respectively

  8. STUDIES ON THE EFFICIENCY OF GRUNDWATER TREATMENT PROCESS WITH ADSORPTION ON ACTIVATED ALUMINA

    Directory of Open Access Journals (Sweden)

    Ewa Szatyłowicz

    2017-07-01

    Full Text Available The one of inorganic sorbents used in water treatment technology is activated alumina. Recommended by the European Commission to remove inorganic impurities, such as arsenic, fluoride, selenium and silicates. The adsorbent is usually applied in granular form, under flow conditions. It can become absorbent material increasingly used due to the presence of arsenic beside iron and manganese in groundwater intakes. The aim of the study was to evaluate the effectiveness of groundwater treatment in the technological system containing adsorption on activated alumina. The experiment was performed on test model CE 581 manufactured by G.U.N.T. Hamburg, in which can extract four treatment stages. The first stage is used in a gravel filter of grain size 1-2 mm, in the second sand filter of grain size 0.4-0.8 mm. The third and fourth phase includes two adsorbers. The first adsorber comprises activated alumina (Al2O3 and the other comprises a granular activated carbon. The study was conducted at different speeds of filtration: 5, 10 and 15 m/h. In the raw water samples and the purified water samples after each treatment step were determined the following parameters: pH, O2 concentration, electrolytic conductivity, SO42-, concentration, NO3- concentration, PO43- concentration, Cl-concentration, color, turbidity, iron and manganese concentration, CODMn, total hardness, calcium hardness, magnesium hardness, content of dissolved substances. Conducted research indicates that optimum filtration rate for most pollution is 15 m/h. Moreover, the presence of activated alumina has contributed to increasing the efficiency of nitrate (V and phosphate (V ions removal.

  9. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    Science.gov (United States)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-12-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

  10. Immersion Freezing of Aluminas: The Effect of Crystallographic Properties on Ice Nucleation

    Science.gov (United States)

    King, M.; Chong, E.; Freedman, M. A.

    2017-12-01

    Atmospheric aerosol particles serve as the nuclei for heterogeneous ice nucleation, a process that allows for ice to form at higher temperatures and lower supersaturations with respect to ice. This process is essential to the formation of ice in cirrus clouds. Heterogeneous ice nucleation is affected by many factors including the composition, crystal structure, porosity, and surface area of the particles. However, these factors are not well understood and, as such, are difficult to account for in climate models. To test the effects of crystal structure on ice nucleation, a system of transition aluminas (Al2O3) that differ only in their crystal structure, despite being compositionally similar, were tested using immersion freezing. Particles were immersed in water and placed into a temperature controlled chamber. Freezing events were then recorded as the chamber was cooled to negative 30 °. Alpha-alumina, which is a member of the hexagonal crystal system, showed a significantly higher temperature at which all particles froze in comparison to other samples. This supports the hypothesis that, since a hexagonal crystal structure is the lowest energy state for ice, hexagonal surface structures would best facilitate ice nucleation. However, a similar sample of hexagonal chi-alumina did not show the same results. Further analysis of the samples will be done to characterize surface structures and composition. These conflicting data sets raise interesting questions about the effect of other surface features, such as surface area and porosity, on ice nucleation.

  11. Properties of single crystal beta''-aluminas

    International Nuclear Information System (INIS)

    Bates, J.B.; Brown, G.M.; Kaneda, T.; Brundage, W.E.; Wang, J.C.; Engstrom, H.

    1979-01-01

    Large single crystals of sodium beta''-alumina were grown by slow evaporation of Na 2 O at 1690 0 C from a mixture of Na 2 CO 3 , MgO, and Al 2 O 3 . Polarized Raman measurements were made on the Na β'' single crystals and on single crystals of Li, K, Rb, and Ag β'' prepared by ion exchange of Na β''. The low frequency Raman spectra of Na, K, Rb, and Ag β'' contained four or more bands due to vibrations of the mobile cations. These results were analyzed by assuming the spectra to be due to the normal modes of a defect cluster consisting of a cation vacancy surrounded by three cations. From model calculations, the Raman band of Na β'' at 33 cm -1 is assigned to the attempt mode for diffusion of Na + ions. The structure of a Ag β'' single crystal was investigated by neutron diffraction, and 20% of the Ag + ion sites were found to be vacant

  12. Coprecipitated nickel-alumina methanation catalysts

    International Nuclear Information System (INIS)

    Kruissink, E.C.

    1981-01-01

    In the last few years there has been a renewed interest in the methanation reaction CO+3H 2 =CH 4 +H 2 O. The investigations described in this thesis were performed in relation to the application of this reaction, within the framework of the so-called 'NFE' project, also called 'ADAM' and 'EVA' project. This project, which has been under investigation in West Germany for some years, aims at the investigation of the feasibility of transporting heat from a nuclear high temperature reactor by means of a chemical cycle. A promising possibility to realize such a cycle exists in applying the combination of the endothermic steam reforming of methane and the exothermic methanation reaction. This thesis describes the investigations into a certain type of methanation catalyst, viz. a coprecipitated nickel-alumina catalyst, with the aim to give more insight into the interrelationship between the preparation conditions on the one hand and catalyst properties such as activity and stability on the other hand. (Auth.)

  13. Red mud flocculation process in alumina production

    Science.gov (United States)

    Fedorova, E. R.; Firsov, A. Yu

    2018-05-01

    The process of thickening and washing red mud is a gooseneck of alumina production. The existing automated systems of the thickening process control involve stabilizing the parameters of the primary technological circuits of the thickener. The actual direction of scientific research is the creation and improvement of models and systems of the thickening process control by model. But the known models do not fully consider the presence of perturbing effects, in particular the particle size distribution in the feed process, distribution of floccules by size after the aggregation process in the feed barrel. The article is devoted to the basic concepts and terms used in writing the population balance algorithm. The population balance model is implemented in the MatLab environment. The result of the simulation is the particle size distribution after the flocculation process. This model allows one to foreseen the distribution range of floccules after the process of aggregation of red mud in the feed barrel. The mud of Jamaican bauxite was acting as an industrial sample of red mud; Cytec Industries of HX-3000 series with a concentration of 0.5% was acting as a flocculant. When simulating, model constants obtained in a tubular tank in the laboratories of CSIRO (Australia) were used.

  14. Surface characterization of low-temperature grown yttrium oxide

    Science.gov (United States)

    Krawczyk, Mirosław; Lisowski, Wojciech; Pisarek, Marcin; Nikiforow, Kostiantyn; Jablonski, Aleksander

    2018-04-01

    The step-by-step growth of yttrium oxide layer was controlled in situ using X-ray photoelectron spectroscopy (XPS). The O/Y atomic concentration (AC) ratio in the surface layer of finally oxidized Y substrate was found to be equal to 1.48. The as-grown yttrium oxide layers were then analyzed ex situ using combination of Auger electron spectroscopy (AES), elastic-peak electron spectroscopy (EPES) and scanning electron microscopy (SEM) in order to characterize their surface chemical composition, electron transport phenomena and surface morphology. Prior to EPES measurements, the Y oxide surface was pre-sputtered by 3 kV argon ions, and the resulting AES-derived composition was found to be Y0.383O0.465C0.152 (O/Y AC ratio of 1.21). The SEM images revealed different surface morphology of sample before and after Ar sputtering. The oxide precipitates were observed on the top of un-sputtered Y oxide layer, whereas the oxide growth at the Ar ion-sputtered surface proceeded along defects lines normal to the layer plane. The inelastic mean free path (IMFP) characterizing electron transport was evaluated as a function of energy in the range of 0.5-2 keV from the EPES method. Two reference materials (Ni and Au) were used in these measurements. Experimental IMFPs determined for the Y0.383O0.465C0.152 and Y2O3 surface compositions, λ, were uncorrected for surface excitations and approximated by the simple function λ = kEp at electron energies E between 500 eV and 2000 eV, where k and p were fitted parameters. These values were also compared with IMFPs resulting from the TPP-2 M predictive equation for both oxide compositions. The fitted functions were found to be reasonably consistent with the measured and predicted IMFPs. In both cases, the average value of the mean percentage deviation from the fits varied between 5% and 37%. The IMFPs measured for Y0.383O0.465C0.152 surface composition were found to be similar to the IMFPs for Y2O3.

  15. Optimized conditions for chelation of yttrium-90-DOTA immunoconjugates.

    Science.gov (United States)

    Kukis, D L; DeNardo, S J; DeNardo, G L; O'Donnell, R T; Meares, C F

    1998-12-01

    Radioimmunotherapy (RIT) with 90Y-labeled immunoconjugates has shown promise in clinical trials. The macrocyclic chelating agent 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (DOTA) binds 90Y with extraordinary stability, minimizing the toxicity of 90Y-DOTA immunoconjugates arising from loss of 90Y to bone. However, reported 90Y-DOTA immunoconjugate product yields have been typically only BAD) was conjugated to the monoclonal antibody Lym-1 via 2-iminothiolane (2IT). The immunoconjugate product, 2IT-BAD-Lym-1, was labeled in excess yttrium in various buffers over a range of concentrations and pH. Kinetic studies were performed in selected buffers to estimate radiolabeling reaction times under prospective radiopharmacy labeling conditions. The effect of temperature on reaction kinetics was examined. Optimal radiolabeling conditions were identified and used in eight radiolabeling experiments with 2IT-BAD-Lym-1 and a second immunoconjugate, DOTA-peptide-chimeric L6, with 248-492 MBq (6.7-13.3 mCi) of 90Y. Ammonium acetate buffer (0.5 M) was associated with the highest uptake of yttrium. On the basis of kinetic data, the time required to chelate 94% of 90Y (four half-times) under prospective radiopharmacy labeling conditions in 0.5 M ammonium acetate was 17-148 min at pH 6.5, but it was only 1-10 min at pH 7.5. Raising the reaction temperature from 25 degrees C to 37 degrees C markedly increased the chelation rate. Optimal radiolabeling conditions were identified as: 30-min reaction time, 0.5 M ammonium acetate buffer, pH 7-7.5 and 37 degrees C. In eight labeling experiments under optimal conditions, a mean product yield (+/- s.d.) of 91%+/-8% was achieved, comparable to iodination yields. The specific activity of final products was 74-130 MBq (2.0-3.5 mCi) of 90Y per mg of monoclonal antibody. The immunoreactivity of 90Y-labeled immunoconjugates was 100%+/-11%. The optimization of 90Y-DOTA chelation conditions represents an important advance in 90Y RIT

  16. Treatment of persistent knee effusions with Yttrium 90

    International Nuclear Information System (INIS)

    Bouyoucef, S.E.; Drahmoune, R.; Mechken, F.; Amimour, A.; Hanni-Haddam, F.; Abtroun, F.; Sellah, M.; Mansouri, B.

    2002-01-01

    Yttrium 90 intra-articular injection is used in persisting active joint of the knee, where medication has failed to resolve chronic inflammation. The effective dose delivered to the synovia is linked to Y 90 activity and depends on the size of the joint space, the synovial structure and thickness and the inflammatory activity of the synovitis. The amount of the injected activity of Y90 was estimated according the volume effusion in 28 pathologic knee of 18 patients aged 18 years and more (mean age 46 years). All patients have persistent knee effusions and most of them have rheumatoid arthritis but others had ankylosing spondylitis, Behcet disease, psoriatic arthritis. According the radiological classification of Steinbrocker, 19 pathological knees were in stage 1, 5 in stage 2 and 4 in stage 3. The mean value of the monthly removed volume of the synovial liquid from the pathological knee was determined during the last month preceding the radiosynoviorthesis and four groups were identified: V0 no evidence of effusion liquid, 0 ml 100ml. The activity of Y 90 was estimated in order to obtain a total of 100 Gray in the envelope of 3 spherical phantoms with the same range of volume as defined above. The lowest activity of Y90, 111 MBq (3mCi) was determined for V0 according a mean value of standard sizes of knees. An activity of 18 MBq (0.5mCi) was added for each stage of 50 ml, so 129 MBq (3.5 mCi) for G1, 148 MBq (4 mCi) for G2 and 166 MBq (4.5 mCi) for G3. Efficacy of Y90 treatment was clinically assessed in all patients according to three parameters: pain, hydrarthrosis and range of joint movement at 1, 3, 6 and 12 months. The results were excellent in 13 knees and good in 9 and for most of them the efficacy of Y 90 was observed after 6 months. The results were less good in 3 knees but with an initial good evolution for all at 1 month. For 4 knees, the efficacy of Y 90 was bad. Although the small number of patients, these results show a high rate, 75%, of successful

  17. Effect of humic acid on sorption of technetium by alumina

    International Nuclear Information System (INIS)

    Kumar, S.; Rawat, N.; Kar, A.S.; Tomar, B.S.; Manchanda, V.K.

    2011-01-01

    Highlights: → Tc sorption on alumina has been studied under aerobic as well anaerobic condition over pH 3-10. → Effect of humic acid on sorption of Tc by alumina has been investigated. → Linear additive modeling and surface complexation modeling were carried out to delineate the role of humic acid in Tc(IV) sorption in ternary system of Tc(IV)-humic acid-alumina. → Sorption of humic acid onto alumina and strong complexation of Tc(IV) with humic acid were found to govern the sorption of Tc(IV) in the ternary system. - Abstract: Sorption of technetium by alumina has been studied in absence as well as in presence of humic acid using 95 Tc m as a tracer. Measurements were carried out at fixed ionic strength (0.1 M NaClO 4 ) under varying pH (3-10) as well as redox (aerobic and reducing anaerobic) conditions. Under aerobic conditions, negligible sorption of technetium was observed onto alumina both in absence and in presence of humic acid. However, under reducing conditions (simulated with [Sn(II)] = 10 -6 M), presence of humic acid enhanced the sorption of technetium in the low pH region significantly and decreased at higher pH with respect to that in absence of humic acid. Linear additive as well as surface complexation modeling of Tc(IV) sorption in presence of humic acid indicated the predominant role of sorbed humic acid in deciding technetium sorption onto alumina.

  18. Enrichment of yttrium from rare earth concentrate by ammonium carbonate leaching and peroxide precipitation

    International Nuclear Information System (INIS)

    Vasconcellos, Mari E. de; Rocha, S.M.R. da; Pedreira, W.R.; Queiroz S, Carlos A. da; Abrao, Alcidio

    2006-01-01

    The rare earth elements (REE) solubility with ammonium carbonate vary progressively from element to element, the heavy rare earth elements (HRE) being more soluble than the light rare earth elements (LRE). Their solubility is function of the carbonate concentration and the kind of carbonate as sodium, potassium and ammonium. In this work, it is explored this ability of the carbonate for the dissolution of the REE and an easy separation of yttrium was achieved using the precipitation of the peroxide from complex yttrium carbonate. For this work is used a REE concentrate containing (%) Y 2 O 3 2.4, Dy 2 O 3 0.6, Gd 2 O 3 2.7, CeO 2 2.5, Nd 2 O 3 33.2, La 2 O 3 40.3, Sm 2 O 3 4.1 and Pr 6 O 11 7.5. The mentioned concentrate was produced industrially from the chemical treatment of monazite sand by NUCLEMON in Sao Paulo. The yttrium concentrate was treated with 200 g L -1 ammonium carbonate during 10 and 30 min at room temperature. The experiments indicated that a single leaching operation was sufficient to get a rich yttrium solution with about 60.3% Y 2 O 3 . In a second step, this yttrium solution was treated with an excess of hydrogen peroxide (130 volumes), cerium, praseodymium and neodymium peroxides being completely precipitated and separated from yttrium. Yttrium was recovered from the carbonate solution as the oxalate and finally as oxide. The final product is an 81% Y 2 O 3 . This separation envisages an industrial application. The work discussed the solubility of the REE using ammonium carbonate and the subsequent precipitation of the correspondent peroxides

  19. Impacts of yttrium substitution on FMR line-width and magnetic properties of nickel spinel ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ishaque, M., E-mail: ishaqdgk1@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ali, Irshad; Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Iqbal, M. Asif [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); College of E & ME, National University of Science and Technology, Islamabad (Pakistan); Islam, M.U. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2015-05-15

    The influence of yttrium (Y) substitution on ferromagnetic resonance (FMR), initial permeability, and magnetic properties of NiFe{sub 2}O{sub 4} ferrites were investigated. It was observed that the FMR line-width decreases with yttrium contents for the substitution level 0≤×≤0.06. Beyond this, the FMR line-width increases with yttrium contents. The nominal composition NiY{sub 0.12}Fe{sub 1.88}O{sub 4} exhibited the smallest FMR line-width ~282 Oe. A significant change in FMR position of nickel–yttrium (Ni–Y) ferrites was observed and it found to exist between 4150 and 4600 Oe. The saturation magnetization was observed to decrease with the increase of yttrium contents and this was referred to the redistribution of cations on octahedral. The coercivity increased from 15 Oe to 59 Oe by increasing the yttrium concentration. The initial permeability decreased from 110 to 35 at 1 MHz by the incorporation of yttrium and this was attributed to the smaller grains which may obstruct the domain wall movement and impede the domain wall motion. The magnetic loss factors of substituted samples exhibit decreasing behavior in the frequency range 1 kHz to 10 MHz. The smaller FMR line-width and reduced magnetic loss factor of the investigated samples suggest the possible use of these materials in high frequency applications. - Highlights: • Influence of Y{sup 3+} substitution on the properties of nickel ferrites is investigated. • Very small FMR line-width (282 Oe) is exhibited by these substituted ferrites. • Fourfold increase in coercivity was observed for NiY{sub 0.24}Fe{sub 1.76}O{sub 4} ferrites.

  20. MCrAlY bond coat with enhanced yttrium

    Science.gov (United States)

    Jablonski, Paul D.; Hawk, Jeffrey A.

    2016-08-30

    One or more embodiments relates to a method of producing an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. The method comprises depositing an MCrAlY material on a substrate, applying an Y.sub.2O.sub.3 paste, and heating the substrate in a non-oxidizing atmosphere at a temperature between 400-1300.degree. C. for a time sufficient to generate the Y--Al.sub.2O.sub.3 layer. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y.sub.2O.sub.3, YAG, and YAP phases.

  1. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Science.gov (United States)

    Kaminaga, Kenichi; Sei, Ryosuke; Hayashi, Kouichi; Happo, Naohisa; Tajiri, Hiroo; Oka, Daichi; Fukumura, Tomoteru; Hasegawa, Tetsuya

    Rare earth sesquioxides like Y2O3 are known as widegap insulators with the highly stable closed shell trivalent rare earth ions. On the other hand, rare earth monoxides such as YO have been recognized as gaseous phase, and only EuO and YbO were thermodynamically stable solid-phase rock salt monoxides. In this study, solid-phase rock salt yttrium monoxide, YO, was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO possesses unusual valence of Y2+ ([Kr] 4d1) . In contrast with Y2O3, YO was narrow gap semiconductor with dark-brown color. The electrical conductivity was tunable from 10-1 to 103 Ω-1 cm-1 by introducing oxygen vacancies as electron donor. Weak antilocalization behavior was observed indicating significant spin-orbit coupling owing to 4 d electron carrier. The absorption spectral shape implies the Mott-Hubbard insulator character of YO. Rare earth monoixdes will be new platform of functional oxides. This work was supported by JST-CREST, the Japan Society for the Promotion of Science (JSPS) with Grant-in-Aid for Scientific Research on Innovative Areas (Nos. 26105002 and 26105006), and Nanotechnology Platform (Project No.12024046) of MEXT, Japan.

  2. Optical properties of ytterbium-doped yttrium oxide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Solomonov, V.I.; Maksimov, R.N. [Institute of Electrophysics UrB RAS, Amundsena 106, 620016 Ekaterinburg (Russian Federation); Ural Federal University Named After the First President of Russia B.N. Yeltsin, Mira 19, 620002 Ekaterinburg (Russian Federation); Osipov, V.V.; Shitov, V.A.; Lipchak, A.I. [Institute of Electrophysics UrB RAS, Amundsena 106, 620016 Ekaterinburg (Russian Federation)

    2017-05-15

    Ytterbium-doped yttrium oxide (Yb:Y{sub 2}O{sub 3}) transparent ceramics with different sintering additives (Lu{sub 2}O{sub 3}, Sc{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2}, or HfO{sub 2}) were fabricated using nanopowders produced by laser ablation. Transmission and photoluminescence spectra of the obtained ceramics were investigated at room temperature. Highest in-line transmittance was over 80% at the wavelength of 1060 nm for 2 mm thick Yb:Y{sub 2}O{sub 3} ceramics with zirconium and hafnium. Divalent Yb ions with the ground state electron configuration 4f{sup 13}6s were revealed. The absorption and emission bands caused by s <-> s transitions of these ions were observed in the IR spectral range of Yb{sup 3+} ions. The superposition of both Yb{sup 3+} and Yb{sup 2+} emission bands leads to an effective broadening of the whole luminescence band. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Structural and dielectric properties of yttrium-substituted hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Kaygili, Omer, E-mail: okaygili@firat.edu.tr [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Dorozhkin, Sergey V. [Kudrinskaja sq. 1-155, 123242 Moscow (Russian Federation); Ates, Tankut [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Canan Gursoy, N. [Department of Microbiology and Clinic Microbiology, Inonu University, 44280 Malatya (Turkey); Keser, Serhat [Department of Chemistry, Faculty of Science, Firat University, 23119 Elazig (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Birkan Selçuk, A. [Technology Department, Saraykoy Nuclear Research and Training Centre, 06983 Ankara (Turkey)

    2015-02-01

    Hydroxyapatite (HAp) samples doped with 0, 2 and 4 at.% of yttrium (Y) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy attached with energy dispersive X-ray (EDX) spectroscopy, antimicrobial activity tests and dielectric studies. The hydroxyl groups observed in FTIR spectra confirmed the formation of HAp phase in the studied samples. The crystallite size, crystallinity degree and lattice parameters of the samples were changed with Y content. The volume of the unit cell was gradually decreased with the addition of Y. Undoped and Y-containing HAp samples were screened to determine their in vitro antimicrobial activities against the standard strains. It was found that no samples have any antimicrobial effect. The relative dielectric permittivity and dielectric loss are affected by Y content. While the alternating current conductivity increases with increasing frequency, it decreases with increasing Y content. - Highlights: • The lattice parameters and crystal size are affected by Y content. • The volume of the unit cell was gradually decreased with the addition of Y. • No samples have any antimicrobial effect. • The alternating current conductivity decreases with increasing Y content.

  4. High density Gd-substituted yttrium iron garnets by coprecipitation

    International Nuclear Information System (INIS)

    Lamastra, Francesca Romana; Bianco, Alessandra; Leonardi, Federica; Montesperelli, Giampiero; Nanni, Francesca; Gusmano, Gualtiero

    2008-01-01

    Gadolinium-substituted yttrium iron garnets are ferrite materials of primary importance in microwave engineering. Stoichiometric powders of nominal composition Y 2.6 Gd 0.4 Fe 5 O 12 (i.e. Fe/(Y + Gd) = 1.67) were prepared by reverse strike coprecipitation of metal nitrates. In order to investigate the influence of composition on phase formation, non-stoichiometric powders were also synthesised. On the basis of DTA/TGA analysis, dried coprecipitates were calcined between 600 deg. C and 1200 deg. C and then characterised by ICP, XRD and HT-XRD. Amorphous coprecipitates crystallise around 700 deg. C in cubic garnet phase along with small amounts of YFeO 3 and/or α-Fe 2 O 3 . Only iron-rich garnets, either pure or Gd-substituted, calcined at 1200 deg. C or above display a single-phase cubic garnet. According to thermal dilatometry results, calcined powders were sintered in air up to 1470 deg. C. The microstructure of sintered ceramics is made up of fine grains, the average size ranging between 3 μm and 13 μm. Density of sintered bodies ranged from 88% to 98%. Ferromagnetic resonance linewidth (ΔH -3dB ) ranged between 4352.9 A m -1 and 4392.7 A m -1 , depending on composition and microstructure

  5. Dielectronic satellites to the Ne-like yttrium resonance lines

    International Nuclear Information System (INIS)

    Osterheld, A.L.; Nilsen, J.; Khakhalin, S.Ya.; Faenov, A.Ya.; Pikuz, S.A.

    1996-01-01

    We present a detailed analysis of the spectrum of satellite transitions to the n=2-3 and n=2-4 Ne-like yttrium resonance lines. Satellite lines from the double excited 2s 2 2p 5 3l3l', 2s 2 2p 5 3l4l', 2s2p 6 3l3l' and 2s2p 6 3l4l' levels of Na-like Y as well as from 2s 2 2p 5 3l3l'3l '' and 2s2p 6 3l3l'3l '' levels of Mg-like Y were observed in spectra from a laser-produced plasma. The X-ray spectra were recorded with high spectral resolution λ/Δλ∼3500-5000 in the wavelength region of the n=2-3 Ne-like resonance lines and with λ/Δλ>1000 in the region of the n=2-4 Ne-like resonance lines. A total of more than 50 spectral features were identified, and their wavelengths were measured. A simple intensity model was developed, which agreed well with the measured spectra and assisted the line identification. The consistency of the model for different spectral regions demonstrates the potential of the Na-like and Mg-like satellite lines for diagnosing plasma conditions. (orig.)

  6. Phase Diagram for Magnon Condensate in Yttrium Iron Garnet Film

    Science.gov (United States)

    Li, Fuxiang; Saslow, Wayne M.; Pokrovsky, Valery L.

    2013-01-01

    Recently, magnons, which are quasiparticles describing the collective motion of spins, were found to undergo Bose-Einstein condensation (BEC) at room temperature in films of Yttrium Iron Garnet (YIG). Unlike other quasiparticle BEC systems, this system has a spectrum with two degenerate minima, which makes it possible for the system to have two condensates in momentum space. Recent Brillouin Light Scattering studies for a microwave-pumped YIG film of thickness d = 5 μm and field H = 1 kOe find a low-contrast interference pattern at the characteristic wavevector Q of the magnon energy minimum. In this report, we show that this modulation pattern can be quantitatively explained as due to unequal but coherent Bose-Einstein condensation of magnons into the two energy minima. Our theory predicts a transition from a high-contrast symmetric state to a low-contrast non-symmetric state on varying the d and H, and a new type of collective oscillation. PMID:23455849

  7. Few-MeV neutrons incident on yttrium

    International Nuclear Information System (INIS)

    Budtz-Jorgensen, C.; Guenther, P.; Smith, A.; Whalen, J.

    1982-09-01

    Neutron total and scattering cross sections of elemental yttrium are measured in the few-MeV region with broad resolutions. The total-cross section measurements extend from approx. = 0.5 to 4.2 MeV in steps of less than or equal to 0.1 MeV. Neutron elastic- and inelastic-scattering cross sections are measured from approx. = 1.5 to 4.0 MeV, at incident-neutron energy intervals of less than or equal to 50 keV and at ten or more scattering angles distributed between 20 and 160 deg. Inelastically-scattered neutron groups are observed corresponding to the excitation of levels at 909 +- 23, 1504 +- 20, 1747 +- 16, 2224 +- 16, 2567 +- 26, 2889 +- 12 and 3104 +- 10 keV. The experimental results are discussed in terms of the spherical optical-statistical, coupled-channels and core-coupling models and compared with corresponding quantities given in the evaluated nuclear data file ENDF/B-V

  8. Deposition of yttrium oxysulfide thin films by atomic layer epitaxy

    International Nuclear Information System (INIS)

    Kukli, K.; University of Tartu, Tartu,; Johansson, L-S.; Nykaenen, E.; Peussa, M.; Ninistoe, L.

    1998-01-01

    Full text: Yttrium oxysulfide is a highly interesting material for optoelectronic applications. It is industrially exploited in the form of doped powder in catholuminescent phosphors, e.g. Y 2 O 2 S: Eu 3+ for colour TV. Attempts to grow thin films of Y 2 O 2 S have not been frequent and only partially successful due to the difficulties in obtaining crystalline films at a reasonable temperature. Furthermore, sputtering easily leads to a sulphur deficiency. Evaporation of the elements from a multi-source offers a better control of the stoichiometry resulting in hexagonal (0002) oriented films at 580 deg C. In this paper we present the first successful thin film growth experiments using a chemical process with molecular precursors. Atomic layer epitaxy (ALE) allows the use of a relatively low deposition temperature and thus compatibility with other technologies. Already at 425 deg C the reaction between H 2 S and Y(thd) 3 (thd = 2,2,6,6 - tetramethyl-heptane-3,5- dione) yields a crystalline Y 2 O 2 S thin film which was characterized by XRD, XRF and XPS

  9. Structural and dielectric properties of yttrium-substituted hydroxyapatites

    International Nuclear Information System (INIS)

    Kaygili, Omer; Dorozhkin, Sergey V.; Ates, Tankut; Canan Gursoy, N.; Keser, Serhat; Yakuphanoglu, Fahrettin; Birkan Selçuk, A.

    2015-01-01

    Hydroxyapatite (HAp) samples doped with 0, 2 and 4 at.% of yttrium (Y) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy attached with energy dispersive X-ray (EDX) spectroscopy, antimicrobial activity tests and dielectric studies. The hydroxyl groups observed in FTIR spectra confirmed the formation of HAp phase in the studied samples. The crystallite size, crystallinity degree and lattice parameters of the samples were changed with Y content. The volume of the unit cell was gradually decreased with the addition of Y. Undoped and Y-containing HAp samples were screened to determine their in vitro antimicrobial activities against the standard strains. It was found that no samples have any antimicrobial effect. The relative dielectric permittivity and dielectric loss are affected by Y content. While the alternating current conductivity increases with increasing frequency, it decreases with increasing Y content. - Highlights: • The lattice parameters and crystal size are affected by Y content. • The volume of the unit cell was gradually decreased with the addition of Y. • No samples have any antimicrobial effect. • The alternating current conductivity decreases with increasing Y content

  10. Photoluminescent properties of nanoporous anodic alumina doped with manganese ions

    Energy Technology Data Exchange (ETDEWEB)

    Gasenkova, I.V. [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Mukhurov, N.I., E-mail: n.mukhurov@ifanbel.bas-net.by [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Zhvavyi, S.P.; Kolesnik, E.E. [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Stupak, A.P. [B.I.Stepanov Institute of Physics of the National Academy of Sciences of Belarus, 68 Nezavisimosti Ave., Minsk 220072 (Belarus)

    2017-05-15

    The results are presented of a comparative study of photoluminescent (PL) properties of unalloyed and Mn-alloyed porous anodic alumina (PAA) subjected to annealing at temperatures in the range of ГђВў{sub a}=200–1300 °ГђВЎ. The possibility of alloying of PAA with metal atoms is illustrated through an example of Mn atoms, and the effect of this impurity on the optical properties of aluminum oxide is examined. Alloying of PAA with Mn ions leads to the formation of complex defects including manganese ions and oxygen vacancies. The difference observed in the spectral dependences of the PL intensity of alloyed and unalloyed specimens is explained by the change in the valence of manganese ions in the complex defects. A decrease has been discovered in the PL intensity of the PL bands and R-lines of Mn and Cr ions in the α-phase under prolonged UV-exposure of the alloyed samples.

  11. Ultrafast excited state deactivation of doped porous anodic alumina membranes

    International Nuclear Information System (INIS)

    Makhal, Abhinandan; Sarkar, Soumik; Pal, Samir Kumar; Yan, Hongdan; Wulferding, Dirk; Cetin, Fatih; Lemmens, Peter

    2012-01-01

    Free-standing, bi-directionally permeable and ultra-thin anodic aluminum oxide (AAO) membranes establish attractive templates (host) for the synthesis of nano-dots and rods of various materials (guest). This is due to their chemical and structural integrity and high periodicity on length scales of 5–150 nm which are often used to host photoactive nano-materials for various device applications including dye-sensitized solar cells. In the present study, AAO membranes are synthesized by using electrochemical methods and a detailed structural characterization using FEG-SEM, XRD and TGA confirms the porosity and purity of the material. Defect-mediated photoluminescence quenching of the porous AAO membrane in the presence of an electron accepting guest organic molecule (benzoquinone) is studied by means of steady-state and picosecond/femtosecond-resolved luminescence measurements. Using time-resolved luminescence transients, we have also revealed light harvesting of complexes of porous alumina impregnated with inorganic quantum dots (Maple Red) or gold nanowires. Both the Förster resonance energy transfer and the nano-surface energy transfer techniques are employed to examine the observed quenching behavior as a function of the characteristic donor–acceptor distances. The experimental results will find their relevance in light harvesting devices based on AAOs combined with other materials involving a decisive energy/charge transfer dynamics. (paper)

  12. Ultrafast excited state deactivation of doped porous anodic alumina membranes

    Science.gov (United States)

    Makhal, Abhinandan; Sarkar, Soumik; Pal, Samir Kumar; Yan, Hongdan; Wulferding, Dirk; Cetin, Fatih; Lemmens, Peter

    2012-08-01

    Free-standing, bi-directionally permeable and ultra-thin anodic aluminum oxide (AAO) membranes establish attractive templates (host) for the synthesis of nano-dots and rods of various materials (guest). This is due to their chemical and structural integrity and high periodicity on length scales of 5-150 nm which are often used to host photoactive nano-materials for various device applications including dye-sensitized solar cells. In the present study, AAO membranes are synthesized by using electrochemical methods and a detailed structural characterization using FEG-SEM, XRD and TGA confirms the porosity and purity of the material. Defect-mediated photoluminescence quenching of the porous AAO membrane in the presence of an electron accepting guest organic molecule (benzoquinone) is studied by means of steady-state and picosecond/femtosecond-resolved luminescence measurements. Using time-resolved luminescence transients, we have also revealed light harvesting of complexes of porous alumina impregnated with inorganic quantum dots (Maple Red) or gold nanowires. Both the Förster resonance energy transfer and the nano-surface energy transfer techniques are employed to examine the observed quenching behavior as a function of the characteristic donor-acceptor distances. The experimental results will find their relevance in light harvesting devices based on AAOs combined with other materials involving a decisive energy/charge transfer dynamics.

  13. Ultrafast excited state deactivation of doped porous anodic alumina membranes

    Energy Technology Data Exchange (ETDEWEB)

    Makhal, Abhinandan; Sarkar, Soumik; Pal, Samir Kumar [Department of Chemical, Biological and Macromolecular Sciences, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Yan, Hongdan; Wulferding, Dirk; Cetin, Fatih; Lemmens, Peter [Institute for Condensed Matter Physics, TU Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig (Germany)

    2012-08-03

    Free-standing, bi-directionally permeable and ultra-thin anodic aluminum oxide (AAO) membranes establish attractive templates (host) for the synthesis of nano-dots and rods of various materials (guest). This is due to their chemical and structural integrity and high periodicity on length scales of 5-150 nm which are often used to host photoactive nano-materials for various device applications including dye-sensitized solar cells. In the present study, AAO membranes are synthesized by using electrochemical methods and a detailed structural characterization using FEG-SEM, XRD and TGA confirms the porosity and purity of the material. Defect-mediated photoluminescence quenching of the porous AAO membrane in the presence of an electron accepting guest organic molecule (benzoquinone) is studied by means of steady-state and picosecond/femtosecond-resolved luminescence measurements. Using time-resolved luminescence transients, we have also revealed light harvesting of complexes of porous alumina impregnated with inorganic quantum dots (Maple Red) or gold nanowires. Both the Foerster resonance energy transfer and the nano-surface energy transfer techniques are employed to examine the observed quenching behavior as a function of the characteristic donor-acceptor distances. The experimental results will find their relevance in light harvesting devices based on AAOs combined with other materials involving a decisive energy/charge transfer dynamics. (paper)

  14. Corrosion resistance characterization of porous alumina membrane supports

    Energy Technology Data Exchange (ETDEWEB)

    Dong Yingchao, E-mail: dongyc9@mail.ustc.edu.cn [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland); USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Lin Bin [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Zhou Jianer [Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Zhang Xiaozhen [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Key Lab of Jiangxi Universities for Inorganic Membranes, National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen Ceramic University (JCU) (China); Ling Yihan; Liu Xingqin; Meng Guangyao [USTC Lab for Solid State Chemistry and Inorganic Membranes, Department of Materials Science and Engineering, University of Science and Technology of China (USTC) (China); Hampshire, Stuart [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)

    2011-04-15

    Tubular porous alumina ceramic membrane supports were fabricated by an extrusion-drying-sintering process and then characterized in detail in terms of corrosion resistance in both H{sub 2}SO{sub 4} and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids. - Research highlights: {yields} Porous alumina membrane supports fabricated by extrusion-drying-sintering process. {yields} Corrosion resistance in 20 wt.% H{sub 2}SO{sub 4} and 1, 5, 10 wt.% NaOH aqueous solutions. {yields} Rapid mass loss and loss of flexural strength occurred in hot NaOH solution. {yields} Resistant to strong acid corrosion with low mass loss, low flexural strength loss. {yields} Porous alumina supports have potential for treatment of strong acid waste liquids.

  15. Enriched fluoride sorption using alumina/chitosan composite

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Natrayasamy, E-mail: natrayasamy_viswanathan@rediffmail.com [Department of Chemistry, Anna University Tiruchirappalli - Dindigul Campus, Dindigul 624 622, Tamil Nadu (India); Meenakshi, S., E-mail: drs_meena@rediffmail.com [Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Tamil Nadu (India)

    2010-06-15

    Alumina possesses an appreciable defluoridation capacity (DC) of 1566 mg F{sup -}/kg. In order to improve its DC, it is aimed to prepare alumina polymeric composites using the chitosan. Alumina/chitosan (AlCs) composite was prepared by incorporating alumina particles in the chitosan polymeric matrix, which can be made into any desired form viz., beads, candles and membranes. AlCs composite displayed a maximum DC of 3809 mg F{sup -}/kg than the alumina and chitosan (52 mg F{sup -}/kg). The fluoride removal studies were carried out in batch mode to optimize the equilibrium parameters viz., contact time, pH, co-anions and temperature. The equilibrium data was fitted with Freundlich and Langmuir isotherms to find the best fit for the sorption process. The calculated values of thermodynamic parameters indicate the nature of sorption. The surface characterisation of the sorbent was performed by FTIR, AFM and SEM with EDAX analysis. A possible mechanism of fluoride sorption by AlCs composite has been proposed. Suitability of AlCs composite at field conditions was tested with a field sample taken from a nearby fluoride-endemic village. This work provides a potential platform for the development of defluoridation technology.

  16. Synthesis of Nano- alumina Powder from Impure Kaolin and its Application for Arsenite Removal from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Ahmad Khodadadi Darban

    2013-07-01

    Full Text Available Adsorption is considered a cost-effective procedure, safer to handle with high removal efficiency. Activated alumina is the most commonly used adsorbent for the removal of arsenic from aqueous solutions. However, activated alumina has a low adsorption capacity and acts kinetically in a slow manner. An ideal adsorbent should have a high surface area, physical and/or chemical stability and be inexpensive. To meet this requirement, nanomeso porous γ-alumina with a high surface area (201.53 m2/g and small particle size (22–36 nm was prepared from inexpensive kaolin as the raw material, by precipitation method. The research results showed that adsorbent has the high adsorption capacity (for initial arsenite concentration up to 10 mg/L, in which 97.65% recovery was achieved. Optimal experimental conditions including pH, initial arsenite concentration and contact time were determined. Langmuir, Freundlich and Dubinin– Radushkevich isotherm models were applied to analyze the experimental data. The best interpretation for the experimental data was given by Langmuir adsorption isotherm equation and the maximum arsenite adsorbed by synthesized nano γ–alumina (qe was found to be 40 (mg/g.

  17. Hydrothermal synthesis and formation mechanism of hexagonal yttrium hydroxide fluoride nanobundles

    International Nuclear Information System (INIS)

    Tian, Li; Sun, QiLiang; Zhao, RuiNi; He, HuiLin; Xue, JianRong; Lin, Jun

    2013-01-01

    Graphical abstract: The formation of yttrium hydroxide fluorides nanobundles can be expressed as a precipitation transformation from cubic NaYF 4 to hexagonal NaYF 4 and to hexagonal Y(OH) 2.02 F 0.98 owing to ion exchange. - Highlights: • Novel Y(OH) 2.02 F 0.98 nanobundles have been successfully prepared by hydrothermal method. • The branched nanobundles composed of numerous oriented-attached nanoparticles has been studied. • The growth mechanism is proposed to be ion exchange and precipitation transformation. - Abstract: This article presents the fabrication of hexagonal yttrium hydroxide fluoride nanobundles via one-pot hydrothermal process, using yttrium nitrate, sodium hydroxide and ammonia fluoride as raw materials to react in propanetriol solvent. The X-ray diffraction pattern clearly reveals that the grown product is pure yttrium hydroxide fluoride, namely Y(OH) 2.02 F 0.98 . The morphology and microstructure of the synthesized product is testified to be nanobundles composed of numerous oriented-attached nanoparticles as observed from the field emission scanning electron microscopy (FESEM). The chemical composition was analyzed by the energy dispersive spectrum (EDS), confirming the phase transformation of the products which was clearly consistent with the result of XRD analysis. It is proposed that the growth of yttrium hydroxide fluoride nanobundles be attributed to ion exchange and precipitation transformation

  18. Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, University of Tunis Elmanar 2092 Tunis (Tunisia); Harima, N.; Koyama, H. [Hyogo University of Teacher Education, Kato, Hyogo 673-1494 (Japan); Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus)

    2012-09-15

    We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA. - Highlights: Black-Right-Pointing-Pointer Porous anodic alumina-rhodamine 110 nanocomposites are elaborated. Black-Right-Pointing-Pointer Efficient energy transfer from the host to Rh110 molecules is evidenced from measurements of photoluminescence and degree of polarization memory spectra. Black-Right-Pointing-Pointer Thermal annealing of porous anodic alumina can improve the process of excitation transfer.

  19. Thermal and Electrical Characterization of Alumina Substrate for Microelectronic Applications

    International Nuclear Information System (INIS)

    Ahmad, S.; Ibrahim, A.; Alias, R.; Shapee, S. M.; Ambak, Z.; Zakaria, S. Z.; Yahya, M. R.; Mat, A. F. A.

    2010-01-01

    This paper reports the effect of sintering temperature on thermal and electrical properties of alumina material as substrate for microelectronic devices. Alumina materials in the form of green sheet with 1 mm thickness were sintered at 1100 deg. C, 1300 deg. C and 1500 deg. C for about 20 hours using heating and cooling rates of 2 deg. C/min. The densities were measured using densitometer and the microstructures of the samples were analyzed using SEM micrographs. Meanwhile thermal and electrical properties of the samples were measured using flash method and impedance analyzer respectively. It was found that thermal conductivity and thermal diffusivity of the substrate increases as sintering temperature increases. It was found also that the dielectric constant of alumina substrate increases as the sintering temperature increases.

  20. Thermal and Electrical Characterization of Alumina Substrate for Microelectronic Applications

    Science.gov (United States)

    Ahmad, S.; Ibrahim, A.; Alias, R.; Shapee, S. M.; Ambak, Z.; Zakaria, S. Z.; Yahya, M. R.; Mat, A. F. A.

    2010-03-01

    This paper reports the effect of sintering temperature on thermal and electrical properties of alumina material as substrate for microelectronic devices. Alumina materials in the form of green sheet with 1 mm thickness were sintered at 1100° C, 1300° C and 1500° C for about 20 hours using heating and cooling rates of 2° C/min. The densities were measured using densitometer and the microstructures of the samples were analyzed using SEM micrographs. Meanwhile thermal and electrical properties of the samples were measured using flash method and impedance analyzer respectively. It was found that thermal conductivity and thermal diffusivity of the substrate increases as sintering temperature increases. It was found also that the dielectric constant of alumina substrate increases as the sintering temperature increases.

  1. Alumina composites for oxide/oxide fibrous monoliths

    International Nuclear Information System (INIS)

    Cruse, T. A.; Polzin, B. J.; Picciolo, J. J.; Singh, D.; Tsaliagos, R. N.; Goretta, K. C.

    2000-01-01

    Most work on ceramic fibrous monoliths (FMs) has focused on the Si 3 N 4 /BN system. In an effort to develop oxidation-resistant FMs, several oxide systems have recently been examined. Zirconia-toughened alumina and alumina/mullite appear to be good candidates for the cell phase of FMs. These composites offer higher strength and toughness than pure alumina and good high-temperature stability. By combining these oxides, possibly with a weaker high-temperature oxide as the cell-boundary phase, it should be possible to product a strong, resilient FM that exhibits graceful failure. Several material combinations have been examined. Results on FM fabrication and microstructural development are presented

  2. Retrospective dosimetry with alumina substrate from electronic components

    International Nuclear Information System (INIS)

    Ekendahl, D.; Judas, L.

    2012-01-01

    Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses. (authors)

  3. Conductivity variations in composites of. alpha. -zirconium phosphate and alumina

    Energy Technology Data Exchange (ETDEWEB)

    Slade, R.C.T.; Knowles, J.A. (Dept. of Chemistry, Exeter Univ. (UK))

    Composite proton-conducting solid electrolytes have been formed from {alpha}-zirconium hydrogen phosphate ({alpha}-Zr(HPO{sub 4}){sub 2}.H{sub 2}O, {alpha}-ZrP) and aluminas (Al{sub 2}O{sub 3}) in varying mole ratios. Conductivity variations as a function of temperature have been characterised and compared to that for a delaminated {alpha}-ZrP (no alumina). There are no appreciable conductivity enhancements on composite formation, but conductivity for materials ca. 50 mole% in alumina can be comparable to the delaminated materials. Differential scanning calorimetry shows the composites to have different thermal properties to simple admixtures. High resolution {sup 31}P NMR studies show reaction to form aluminium phosphate at the interface between components. (orig.).

  4. Radiation silver paramagnetic centers in a beta-alumina crystal

    International Nuclear Information System (INIS)

    Badalyan, A.G.; Zhitnikov, R.A.

    1985-01-01

    Silver paramagnetic centers in a β-alumina crystal, formed after X-ray radiation at 77 K, are investigated by the EPR method. Silver enters the β-alumina crystal, substituting sodium and potassium ions in a mirror plane. Crystals with substitution from 0.1 to 100% of alkali metal ions by Ag + ions are investigated. Silver atomic centers (Ag 0 -centers), formed by electron capture with the Ag + ion, are firstly detected and investigated in the β-alumina. Hole Ag 2+ -centers are investigated and detected in crystals with high concentration of Ag + . By studying the orientation dependence of a g-factor it is established that hole capture by the Ag + ion is accompanied by Ag 2+ ion displacement from the position, Ag + being primarity taken up (Beavers-Roth or anti- Beavers-Roth) to the position between two oxygen ions in the mirror plane

  5. Pressureless sintering behavior of injection molded alumina ceramics

    Directory of Open Access Journals (Sweden)

    Liu W.

    2014-01-01

    Full Text Available The pressureless sintering behaviors of two widely used submicron alumina (MgOdoped and undoped with different solid loadings produced by injection molding have been studied systematically. Regardless of the sinterability of different powders depending on their inherent properties, solid loading plays a critical role on the sintering behavior of injection molded alumina, which greatly determines the densification and grain size, and leads to its full densification at low temperatures. As compared to the MgO-doped alumina powder, the undoped specimens exhibit a higher sinterability for its smaller particle size and larger surface area. While full densification could be achieved for MgO-doped powders with only a lower solid loading, due to the fact that MgO addition can reduce the detrimental effect of the large pore space on the pore-boundary separation.

  6. Synthesis of alumina powders by precipitation method and solvothermal treatment

    International Nuclear Information System (INIS)

    Politchuk, J.O.; Lima, N.B.; Lazar, D.R.R.; Ussui, V.; Yoshito, W.K.

    2012-01-01

    The improvement of alumina powders synthesis processes has been focused on the preparation of ceramic powders with well defined crystalline structure and with high specific surface area and nanometric particle size without formation of hard agglomerates. For this purpose the precipitation step should be studied and and also the temperature of alumina crystallization should be reduced. The aim of this study was to obtain alumina powders by hydroxide precipitation with ammonia in the presence of cationic surfactant, followed by solvothermal treatment and calcination. The powders were characterized by TG/DTA, X-ray diffraction, surface area measurements by gas adsorption (BET) and scanning electron microscopy. The results showed that powders produced by solvothermal treatment without surfactant have higher crystallinity. However the presence of CTAB enhances 240% the specific surface area compared with powders produced without this reagent (author)

  7. Right Gastric Artery Embolization Prior to Treatment with Yttrium-90 Microspheres

    International Nuclear Information System (INIS)

    Cosin, Octavio; Bilbao, Jose Ignacio; Alvarez, Sergio; Luis, Esther de; Alonso, Alberto; Martinez-Cuesta, Antonio

    2007-01-01

    Purpose. Intra-arterial infusion of yttrium-90 microspheres is a form of radiation treatment for unresectable hepatic neoplasms. Misdeposition of particles in the gastroduodenal area such as the right gastric artery (RGA) may occur with serious consequences. We present a series of patients who underwent a detailed vascular study followed by RGA embolization. Special emphasis is placed on anatomic variations and technical considerations .Methods. In a 1 year period, 27 patients were treated. Initial vascular evaluation was performed, with careful attention to anatomic variants or extrahepatic arterial supply, especially to the gastroduodenal area. Embolization of such arteries was planned if needed. RGA embolization was performed antegradely from the hepatic artery or retrogradely via the left gastric artery (LGA). Postprocedural follow-up included clinical interview and gastroscopy if necessary. Results. RGA embolization was performed in 9 patients presenting with primary (n = 3) or metastatic liver tumors (n 6). Six patients underwent antegrade RGA embolization and 3 had embolization done retrogradely via the LGA. Retrograde access was chosen for anatomic reasons. None of the patients complained of gastroduodenal symptoms. Conclusion. RGA embolization can help minimize the gastroduodenal deposition of radioactive particles. RGA embolization should routinely be carried out. The procedure can be performed, with similar technical success, by both anterograde and retrograde approaches

  8. A Woman with Black Beads in Her Stomach: Severe Gastric Ulceration Caused by Yttrium-90 Radioembolization

    Directory of Open Access Journals (Sweden)

    Indu S. Voruganti

    2018-01-01

    Full Text Available Radioembolization (RE is a selective internal radiation therapy (SIRT delivering targeted, high-dose, intra-arterial radiation directly to the vascular supply of liver tumors. Complications can occur due to aberrant deposition or migration of radiation microspheres into nontarget locations, including normal hepatic parenchyma, lungs, pancreas, and upper gastrointestinal (UGI tract. We report a case of gastric ulcers due to yttrium-90 (90Y seed migration to the stomach to alert clinicians to this rare cause of gastric injury. A 57-year-old woman with stage IV breast cancer with liver and lung metastases presented to the hospital with 2 months of worsening nausea and vomiting. Two months prior, she had received SIRT with 90Y microspheres without complications. Upper GI endoscopy showed diffuse gastritis and extensive antral ulceration. Biopsies revealed black, spherical foreign bodies, consistent with 90Y microspheres, documenting radiation injury. Radiation-induced UGI ulceration is caused by direct radiation injury from beta-radiation. Delay in diagnosis may be due to the nonspecificity of symptoms and temporal delay of symptom onset from SIRT, which was 2 months in our patient. Also, complaints may be attributed erroneously to adjuvant chemotherapy or widespread metastatic disease. Clinicians must consider radiation-associated toxicity in any SIRT-treated patient developing abdominal symptoms.

  9. Evaluation of magnesium-yttrium alloy as an extraluminal tracheal stent.

    Science.gov (United States)

    Luffy, Sarah A; Chou, Da-Tren; Waterman, Jenora; Wearden, Peter D; Kumta, Prashant N; Gilbert, Thomas W

    2014-03-01

    Tracheomalacia is a relatively rare problem, but can be challenging to treat, particularly in pediatric patients. Due to the presence of mechanically deficient cartilage, the trachea is unable to resist collapse under physiologic pressures of respiration, which can lead to acute death if left untreated. However, if treated, the outcome for patients with congenital tracheomalacia is quite good because the cartilage tends to spontaneously mature over a period of 12 to 18 months. The present study investigated the potential for the use of degradable magnesium-3% yttrium alloy (W3) to serve as an extraluminal tracheal stent in a canine model. The host response to the scaffold included the formation of a thin, vascularized capsule consisting of collagenous tissue and primarily mononuclear cells. The adjacent cartilage structure was not adversely affected as observed by bronchoscopic, gross, histologic, and mechanical analysis. The W3 stents showed reproducible spatial and temporal fracture patterns, but otherwise tended to corrode quite slowly, with a mix of Ca and P rich corrosion product formed on the surface and observed focal regions of pitting. The study showed that the approach to use degradable magnesium alloys as an extraluminal tracheal stent is promising, although further development of the alloys is required to improve the resistance to stress corrosion cracking and improve the ductility. Copyright © 2013 Wiley Periodicals, Inc.

  10. Cylindrical Three-Dimensional Porous Anodic Alumina Networks

    Directory of Open Access Journals (Sweden)

    Pedro M. Resende

    2016-11-01

    Full Text Available The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates.

  11. Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

    OpenAIRE

    Kikuchi, Tatsuya; Yamamoto, Tsuyoshi; Natsui, Shungo; Suzuki, Ryosuke O.

    2014-01-01

    The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M squaric acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400...

  12. Behaviour modelling of two aluminas in divergent spherical pyrotechnical experiments

    International Nuclear Information System (INIS)

    Malaise, F.; Tranchet, J.Y.; Collombet, F.

    1997-01-01

    Two pure aluminas of different characteristics have been subjected to the propagation of a longitudinal divergent spherical shock wave through pyrotechnical experiments. An approach combining a phenomenological analysis and numerical 1D-calculations is proposed to study the behaviour of these aluminas submitted to that type of wave loading. The modelling, proposed in a previous paper, is refined and gives satisfying experimentation-calculation correlations. An analysis of the influence exerted by the various encountered phenomena (plastic activity, pore closure, microcracking) is performed. The significant consequence of the activation of damage with an extension criterion is also underlined. (orig.)

  13. Comparative study on sintered alumina for ballistic shielding application

    International Nuclear Information System (INIS)

    Melo, Francisco Cristovao Lourenco de; Goncalves, Diniz Pereira

    1997-01-01

    This work presents a development of the armor made from special ceramic materials and kevlar. An experimental investigation was conducted to study the ballistic penetration resistance on three samples taken from sintered alumina: a commercial one and two formulations A and B made in IAE/CTA. The main differences between the two formulations was the grain size and bend resistance. The knowledge of the mechanisms during the penetration and perforation process allowed to apply a ductile composite laminate made form kevlar under the alumina to delay its rupture. The last ballistic test showed how a Weibull's modulii and other mechanical properties are able to improve ballistic penetration resistance. (author)

  14. Separation of Yttrium from Rare Earth Concentrates in Fractional Hydroxide Precipitation

    International Nuclear Information System (INIS)

    Tri Handini; Purwoto; Mulyono

    2007-01-01

    Yttrium has been separated from rare earth concentrates by precipitation in fractional hydroxide using urea. The purpose of this research is to increase the yttrium rate resulting from the sedimentary process through separation of yttrium from other rare earth in fractional hydroxide precipitation using urea. In this research, we study the process variable of the concentration of urea, the ratio of feed volume to condensation volume of urea, as well as the temperature. Determination analysis of the rare earth rate is conducted using an X-ray spectrometer. The best result Y=92.89 % is obtained at a concentration of urea of 50 %, a level of precipitation of 3 times, and a temperature of 80°C. (author)

  15. Fabrication of dense yttrium oxyfluoride ceramics by hot pressing and their mechanical, thermal, and electrical properties

    Science.gov (United States)

    Tahara, Ryuki; Tsunoura, Toru; Yoshida, Katsumi; Yano, Toyohiko; Kishi, Yukio

    2018-06-01

    Excellent corrosion-resistant materials have been strongly required to reduce particle contamination during the plasma process in semiconductor production. Yttrium oxyfluoride can be a candidate as highly corrosion-resistant material. In this study, three types of dense yttrium oxyfluoride ceramics with different oxygen contents, namely, YOF, Y5O4F7 and Y5O4F7 + YF3, were fabricated by hot pressing, and their mechanical, thermal, and electrical properties were evaluated. Y5O4F7 ceramics showed an excellent thermal stability up to 800 °C, a low loss factor, and volume resistivity comparable to conventional plasma-resistant oxides, such as Y2O3. From these results, yttrium oxyfluoride ceramics are strongly suggested to be used as electrostatic chucks in semiconductor production.

  16. Tribological effects of yttrium and nitrogen ion implantation on a precipitation hardening stainless steel

    International Nuclear Information System (INIS)

    Alonso, F.; Arizaga, A.; Garcia, A.; Onate, J.I.

    1994-01-01

    Yttrium, nitrogen and combined yttrium and nitrogen implantations have been carried out on an ASTM A286 precipitation hardening iron base alloy to evaluate the benefits in their tribological behaviour. Microindentation tests have shown a significant 20%-60% increment in hardness on the nitrogen implanted material, with a limited improvement in elastic recovery of the indentation. An abrasive test on the same material has also produced a 50% reduction in scratch depth. Y + and Y + +N + implantations also hardened the material but to a lesser extent. Reciprocating ball on disk friction and wear testing at 400 C resulted in very severe damage in all cases. X-ray photoelectron spectroscopy analyses combined with Ar sputtering have disclosed that nitrogen is mainly in a nitrided form, yttrium remains oxidized at the surface, below which there is an apparent increase in the metallic bond. ((orig.))

  17. Fluorimetric determination of yttrium by methyl-bis(8-hydraxy--- 2-quinolyl)amine

    International Nuclear Information System (INIS)

    Golovina, A.P.; Kachin, S.V.; Runov, V.K.; Fakeeva, O.A.

    1982-01-01

    Using a method of mathematical Box-Wilson experiment planning the optimum conditions of yttrium fluorimetric determination by methyl-bis (8-hydroxy-2-quinolyl) amine (pH 7.5, csub(R)=1.4x10sup(-5) M) with the determination limit=0.05 μg/ml are found. An extraction-fluorimetric method of yttrium determination by methyl-bis (8-hydroxy-2-quinolyl) amine is developed. The extraction has been realized with aliphatic alcohols at pH > 11. The method is characteristic of the lowest determination limit (0.01 μg/ml) as compared with the known ones. The possibility is shown of yttrium determination in the presence of 5000-multiple aluminium contents, stoichiometric contents of La, Lu, Fe (3), U (6), tartrates, citrates

  18. Positive effect of yttrium on the reduction of pores in cast Al alloy

    International Nuclear Information System (INIS)

    Hua, Guomin; Ahmadi, Hojat; Nouri, Meisam; Li, Dongyang

    2015-01-01

    Mechanical and electrochemical properties of Al alloys can be improved by adding a small amount of rare-earth such as yttrium. Here we demonstrate that adding yttrium also helps suppress the porosity in cast Al alloys, thus minimizing its detrimental effect on mechanical properties of the alloys. The mechanism behind is elucidated based on the hydrogen binding energies and the diffusion activation energies of hydrogen atoms in Al and Al–Y phases, calculated using the first-principle method. - Highlights: • The porosity of commercial Al alloy can be reduced by additive yttrium. • Formed Al 3 Y phase helps reduce homogeneous nucleation of hydrogen bubbles. • Formed Al 3 Y and Al 2 Y phases could suppress the growth of hydrogen bubbles

  19. Effects of yttrium 90 on experimental allergic arthritis in rabbits

    International Nuclear Information System (INIS)

    Meier-Ruge, W.; Mueller, W.; Pavelka, K.

    1976-01-01

    Fifteen weeks after allergic arthritis developed in the knee joint of 17 immunized rabbits, 8 animals were given an injection of 200 μCi yttrium 90( 90 Y) into the left joint cavity and 7 were injected with 400 μCi. The animals were sacrificed at 2, 4, 8, 12, and 16 weeks, and at 6 to 12 months after the injection. Two uninjected animals used as morphological controls were sacrificed 13 weeks after immunization, and showed allergic arthritis had progressed to severe inflammation of the knee joint marked by massive round-cell infiltration, oedema, and proliferation of synovial mesothelium in the synovial villi and joint capsule. Treatment with 90 Y was effective 2 weeks after injection and the disappearance of inflammatory odema and marked regression of round-cell infiltration. This was accompanied by degeneration of the synovial mesothelium and fibrosis of the subsynovial tissue and synovial vessels as a secondary effect of the radiation. In the animals with severe allergic arthritis, the healing effects of 90 Y were more marked than the secondary effects of the radiation which were dose-dependent. Treatment with 90 Y of arthritic knee joints with the lowest effective dose of the isotope - if necessay with repeated application - seems justified. A single large dose does not have a greater therapeutic effect and causes more radiation damage to the joint. In view of the possible secondary effects in the joint, the indication for 90 Y therapy should be restricted, particularly in young patients, to cases of chronic relapsing arthritis unresponsive to other treatment. (U.K.)

  20. Planar gamma camera imaging and quantitation of Yttrium-90 bremsstrahlung

    International Nuclear Information System (INIS)

    Shen, S.; DeNardo, G.L.; Yuan, A.

    1994-01-01

    Yttrium-90 is a promising radionuclide for radioimmunotherapy of cancer because of its energetic beta emissions. Therapeutic management requires quantitative imaging to assess the pharmacokinetics and radiation dosimetry of the 90 Y-labeled antibody. Conventional gamma photon imaging methods cannot be easily applied to imaging of 90 Y-bremsstrahlung because of its continuous energy spectrum. The sensitivity, resolution and source-to-background signal ratio (S/B) of the detector system for 90 Y-bremsstrahlung were investigated for various collimators and energy windows in order to determine optimum conditions for quantitative imaging. After these conditions were determined, the accuracy of quantitation of 90 Y activity in an Alderson abdominal phantom was examined. When the energy-window width was increased, the benefit of increased sensitivity outweighed degradation in resolution and S/B ratio until the manufacturer's energy specifications for the collimator were exceeded. Using the same energy window, the authors improved resolution and S/B for the medium-energy (ME) collimator when compared to the low-energy, all-purpose (LEAP) collimator, and there was little additional improvement using the high-energy (HE) collimator. Camera sensitivity under tissue equivalent conditions was 4.2 times greater for the LEAP and 1.7 times greater for the ME collimators when compared to the HE collimator. Thus, the best, most practical selections were found to be the ME collimator and an energy window of 55-285 keV. When they used these optimal conditions for image acquisition, the estimation of 90 Y activity in organs and tumors was within 15% of the true activities. The results for this study suggest that reasonable accuracy can be achieved in clinical radioimmunotherapy using 90 Y-bremsstrahlung quantitation. 28 refs., 5 figs., 7 tabs

  1. Rare earth activated yttrium aluminate phosphors with modulated luminescence.

    Science.gov (United States)

    Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

    2016-06-01

    Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  3. Effects of yttrium 90 on experimental allergic arthritis in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Meier-Ruge, W [Sandoz A.G., Basel (Switzerland); Mueller, W; Pavelka, K

    1976-02-01

    Fifteen weeks after allergic arthritis developed in the knee joint of 17 immunized rabbits, 8 animals were given an injection of 200 ..mu..Ci yttrium 90(/sup 90/Y) into the left joint cavity and 7 were injected with 400 ..mu..Ci. The animals were sacrificed at 2, 4, 8, 12, and 16 weeks, and at 6 to 12 months after the injection. Two uninjected animals used as morphological controls were sacrificed 13 weeks after immunization, and showed allergic arthritis had progressed to severe inflammation of the knee joint marked by massive round-cell infiltration, oedema, and proliferation of synovial mesothelium in the synovial villi and joint capsule. Treatment with /sup 90/Y was effective 2 weeks after injection and the disappearance of inflammatory odema and marked regression of round-cell infiltration. This was accompanied by degeneration of the synovial mesothelium and fibrosis of the subsynovial tissue and synovial vessels as a secondary effect of the radiation. In the animals with severe allergic arthritis, the healing effects of /sup 90/Y were more marked than the secondary effects of the radiation which were dose-dependent. Treatment with /sup 90/Y of arthritic knee joints with the lowest effective dose of the isotope - if necessay with repeated application - seems justified. A single large dose does not have a greater therapeutic effect and causes more radiation damage to the joint. In view of the possible secondary effects in the joint, the indication for /sup 90/Y therapy should be restricted, particularly in young patients, to cases of chronic relapsing arthritis unresponsive to other treatment.

  4. Dielectronic satellites to the Ne-like yttrium resonance lines

    Energy Technology Data Exchange (ETDEWEB)

    Osterheld, A.L. [Lawrence Livermore National Lab., CA (United States); Nilsen, J. [Lawrence Livermore National Lab., CA (United States); Khakhalin, S.Ya. [MISDC, VNIIFTRI, Mendeleevo (Russian Federation); Faenov, A.Ya. [MISDC, VNIIFTRI, Mendeleevo (Russian Federation); Pikuz, S.A. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.

    1996-09-01

    We present a detailed analysis of the spectrum of satellite transitions to the n=2-3 and n=2-4 Ne-like yttrium resonance lines. Satellite lines from the double excited 2s{sup 2}2p{sup 5}3l3l`, 2s{sup 2}2p{sup 5}3l4l`, 2s2p{sup 6}3l3l` and 2s2p{sup 6}3l4l` levels of Na-like Y as well as from 2s{sup 2}2p{sup 5}3l3l`3l{sup ``} and 2s2p{sup 6}3l3l`3l{sup ``} levels of Mg-like Y were observed in spectra from a laser-produced plasma. The X-ray spectra were recorded with high spectral resolution {lambda}/{Delta}{lambda}{approx}3500-5000 in the wavelength region of the n=2-3 Ne-like resonance lines and with {lambda}/{Delta}{lambda}>1000 in the region of the n=2-4 Ne-like resonance lines. A total of more than 50 spectral features were identified, and their wavelengths were measured. A simple intensity model was developed, which agreed well with the measured spectra and assisted the line identification. The consistency of the model for different spectral regions demonstrates the potential of the Na-like and Mg-like satellite lines for diagnosing plasma conditions. (orig.).

  5. Quantitative phase analysis of alumina/calcium-hexaluminate composites using neutron diffraction data and the Rietveld method

    International Nuclear Information System (INIS)

    Asmi, D.; Low, I.M.; O'Connor, B.H.; Kennedy, S.J.

    2000-01-01

    Full text: The Al 2 O 3 -CaO system is the basis of an important class of high-temperature refractories in the steel industry. It contains a number of stable intermediate compounds which include C 3 A, C 12 A 7 , CA, CA 2 , and CA 6 . These calcium aluminates are also important constituents of high alumina cement and have been used to produce high-strength and high-toughness ceramic-polymer composite materials. More recently, alumina composites containing 30 wt% CA 6 platelets have been developed by An et al which show characteristics of self-reinforcement and enhanced toughening through crack-bridging. In this paper, we describe the use of high-temperature neutron diffraction to monitor the in-situ phase formation and abundances of calcium aluminates (CA, CA 2 , and CA 6 ) in alumina composites containing 5-50 wt % CA 6 .at temperatures in the range 1000 - 1600 deg C. These composites were produced using reaction sintering of alumina and calcium oxide. For comparison purposes, control samples of pure α-alumina and CA 6 were also produced. Determination of relative phase abundances in these materials has been performed using the standardless Rietveld refinement method. Results show that the relative phase abundance of calcium aluminates in the composites increased with temperature and in proportion with the amount of calcium oxide present. The formation temperatures of CA, CA 2 , and CA 6 have been observed to occur at 1000 deg , 1200 deg, and ∼1350 deg C respectively, which agree well with results obtained from x-ray diffraction, synchrotron radiation diffraction and differential thermal analysis

  6. Spectrophotometric determination of yttrium with 2-(2-thiazolylazo)-5-dimethylaminophenol

    International Nuclear Information System (INIS)

    Tsurumi, Chikao; Furuya, Keiichi.

    1975-01-01

    Spectrophotometric determination of small amounts of yttrium with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) in the presence of zephiramine was investigated. The recommended procedures were as follows; 2.0 ml of water, 7.0 ml of TAM-methanolic solution (2x10 -4 mol/l) and 2.0 ml of zephiramine-aqueous solution (1x10 -2 mol/l) were added to a solution containing less than 35 μg of yttrium and its pH was adjusted to 8.0 with 0.1 mol/l ammonium chloride-0.1 mol/l ammonium hydroxide solution. The solution was transferred to a 25 ml volumetric flask and diluted to the mark with water. After 20 minutes, the absorbance at 575 nm against a reagent blank was measured. The color of yttrium-TAM complex is reddish-violet in the presence of zephiramine and is stable for 90 minutes after color development. The yttrium-TAM complex shows an absorption maximum at 575 nm. The absorbance at 575 nm is constant in a pH range from 7.5 to 8.3. The molar extinction coefficient at this wavelength is 7.2x10 4 l.mol -1 .cm -1 . The band obeys Beer's law up to the concentration of 1.4 μg/ml of yttrium. The molar ratio of yttrium to TAM in the complex is 1 : 2. A number of ions interfere with the determination can be masked by the addition of various masking agents and removed in terms of trioctylamine-xylene extraction. Manganese, tantalum, tin(II), citrate and tartrate ions interfere with the determination. (auth.)

  7. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    Science.gov (United States)

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  8. Ultrasonic measurements and other allied parameters of yttrium soaps in mixed organic solvents

    International Nuclear Information System (INIS)

    Mehrotra, K.N.; Tandon, K.

    1990-01-01

    The ultrasonic measurements of yttrium soaps were made in a mixture of 70 % benzene and 30 % dimethylsulfoxide (ν/ν) to determine the critical micelle concentration, soap-solvent interaction and various acoustic and thermodynamic parameters. The values of the CMC decrease with increasing chainlength of fatty acid constituent of the soap molecule and are in agreement with the values obtained from other micellar properties. The various acoustic parameters (intermolecular freelength, adiabatic compressibility, apparent molar compressibility, specific acoustic impedance, apparent molar volume, molar sound velocity, solvation number, available volume and relative association) for yttrium soaps (myristate, palmitate, stearate and oleate) have been evaluated by ultrasonic velocity measurements. (Authors)

  9. Method of growing yttrium aluminate and/or lanthanide single crystals with perovskite structure

    International Nuclear Information System (INIS)

    Kvapil, Jiri; Perner, B.; Kvapil, Josef; Blazek, K.

    1989-01-01

    Single crystals of yttrium aluminate and/or lanthanide with perovskite structure are grown from melt in a vacuum at a pressure of gas residues of max. 0.01 Pa. The melt contains 1±0.05 gram-ions of aluminium per gram-ion of yttrium and/or lanthanides. The single crystals are then heated in a vacuum (0.01 Pa) at temperatures of 1,450 to 1,800 degC for 2 to 3 hours. (B.S.)

  10. Elaboration and characterisation of yttrium oxide and hafnium oxide powders by the sol-gel process

    International Nuclear Information System (INIS)

    Hours, T.

    1988-01-01

    The two classical sol-gel processes, colloidal and polymeric are studied for the preparation of yttrium oxide and hafnium oxide high performance powders. In the colloidal process, controlled and reproducible conditions for the preparation of yttrium oxide and hafnium oxide sols from salts or alkoxides are developed and the hydrothermal synthesis monodisperse hafnium oxide colloids is studied. The polymeric process is studied with hafnium ethyl-hexylate, hydrolysis kinetics for controlled preparation of sols and gels is investigated. Each step of preparation is detailed and powders obtained are characterized [fr

  11. Separation coefficients of liquid-vapor in systems formed by yttrium chloride with some impurities

    International Nuclear Information System (INIS)

    Volkov, V.T.; Nikiforova, T.V.; Nisel'son, L.A.; Telegin, G.F.

    1990-01-01

    Using equilibrium Rayleigh distillation in the 800-950 deg C temperature range, separation coefficients of liquid-vapor for systems, formed by yttrium chloride with Co, Cr, Ni, Mn, Fe, Cu, Na, K, Mg, Ca, Li impurities are determined. The impurity concentration lies within 0.02-0.4 mass. % limits of each impurity, and total impurity concentration does not exceed 1 mass. %. The tested impurities, except for calcium, are more volatile than the base, yttrium trichloride. In most systems negative deviation from the Raoult's law is observed

  12. Lack of rise in serum prolactin following yttrium-90 interstitial irradiation for acromegaly

    International Nuclear Information System (INIS)

    Clark, A.J.L.; Chahal, P.; Mashiter, K.; Joplin, G.F.

    1983-01-01

    The authors have investigated the possibility that the increase in serum PRL levels observed in patients with acromegaly treated with external irradiation could be due to damage to the hypothalamus or portal vessels, by comparing the effects of yttrium-90 interstitial irradiation, which is highly localised and does not normally extend to the hypothalamus, in a similar series of patients. These results are consistent with the hypothesis; a less likely explanation is that an overgrowth of radio-resistant PRL-secreting tumour cells is occurring after external irradiation, but not after yttrium-90 implantation. (author)

  13. Lack of rise in serum prolactin following yttrium-90 interstitial irradiation for acromegaly

    Energy Technology Data Exchange (ETDEWEB)

    Clark, A.J.L.; Chahal, P.; Mashiter, K.; Joplin, G.F. (Royal Postgraduate Medical School, London (UK))

    1983-11-01

    The authors have investigated the possibility that the increase in serum PRL levels observed in patients with acromegaly treated with external irradiation could be due to damage to the hypothalamus or portal vessels, by comparing the effects of yttrium-90 interstitial irradiation, which is highly localised and does not normally extend to the hypothalamus, in a similar series of patients. These results are consistent with the hypothesis; a less likely explanation is that an overgrowth of radio-resistant PRL-secreting tumour cells is occurring after external irradiation, but not after yttrium-90 implantation.

  14. High-resolution structural characterization and magnetic properties of epitaxial Ce-doped yttrium iron garnet thin films

    Science.gov (United States)

    Li, Zhong; Vikram Singh, Amit; Rastogi, Ankur; Gazquez, Jaume; Borisevich, Albina Y.; Mishra, Rohan; Gupta, Arunava

    2017-07-01

    Thin films of magnetic garnet materials, e.g. yttrium iron garnet (Y3Fe5O12, YIG), are useful for a variety of applications including microwave integrated circuits and spintronics. Substitution of rare earth ions, such as cerium, is known to enhance the magneto-optic Kerr effect (MOKE) as compared to pure YIG. Thin films of Ce0.75Y2.25Fe5O12 (Ce:YIG) have been grown using the pulsed laser deposition (PLD) technique and their crystal structure examined using high resolution scanning transmission electron microscopy. Homogeneous substitution of Ce in YIG, without oxidation to form a separate CeO2 phase, can be realized in a narrow process window with resulting enhancement of the MOKE signal. The thermally generated signal due to spin Seebeck effect for the optimally doped Ce:YIG films has also been investigated.

  15. A Short Overview on the Biomedical Applications of Silica, Alumina and Calcium Phosphate-based Nanostructured Materials.

    Science.gov (United States)

    Ellahioui, Younes; Prashar, Sanjiv; Gómez-Ruiz, Santiago

    2016-01-01

    This article reviews the use of silica, alumina and calcium phosphate-based nanostructured materials with biomedical applications. A short introduction on the use of the materials in Science, Nanotechnology and Health is included followed by a revision of each of the selected materials. A description of the principal synthetic methods used in the preparation of the materials in nanostructured form is included. The most widely used applications in biomedicine are reviewed including, for example drug-delivery, bone regeneration, imaging, sensoring amongst others. Finally, a short description of the toxicity and cytotoxicity associated with each of the materials of this revision is presented. This short literature revision serves to demonstrate the very promising future ahead of nanosystems based on silica, alumina and calcium phosphate for biological and biomedical applications.

  16. Low-cost shape-control synthesis of porous carbon film on β″-alumina ceramics for Na-based battery application

    Science.gov (United States)

    Hu, Yingying; Wen, Zhaoyin; Wu, Xiangwei; Jin, Jun

    2012-12-01

    Porous carbon films with tunable pore structure to modify the β″-alumina electrolyte surface are fabricated through a low-cost and direct wet chemistry method with glucose and poly(methyl-methacrylate) (PMMA) as precursors. FTIR analysis confirms the effective connection between the carbohydrate and the pore-forming agent PMMA through hydrogen bonds. The experimental results indicate that the structural parameters of the porous carbon films, including mean pore size and film thickness, can be tuned simply by adjusting the amount of PMMA in the glucose/PMMA composite. This soft-template-assisted method could be readily extended to modify any other ceramic surfaces. The porous carbon films are demonstrated to greatly improve the wettability of the β″-alumina ceramics by molten sodium. Na/β″-alumina/Na cells are used to investigate the interfacial properties between sodium and the β″-alumina electrolyte. The results obtained at 350 °C reveal that the polarization behavior of the cell is alleviated by the porous coating. This work represents a successful method to coat ceramics with porous carbon and offers a promising solution to overcome the polarization problems of the sodium/β″-alumina interface in Na-based batteries.

  17. Behaviour of iron and titanium species in cryolite-alumina melts

    OpenAIRE

    Jentoftsen, Trond Eirik

    2000-01-01

    The solubility of divalent iron oxide in cryolite-based melts was studied. Both electrochemical and chemical techniques were employed. To ensure that only divalent iron was present in solution, the melt was contained in an iron crucible under an atmosphere of argon. The experimental work included investigation of the solubility as a function of alumina concentration, temperature and cryolite ratio (CR = NaF/AlF3 molar ratio). The solubility at 1020 ºC was found to decrease from 4.17 wt% Fe in...

  18. High-frequency characteristics of glass/ceramic composite and alumina multilayer structures

    International Nuclear Information System (INIS)

    Niwa, K.; Suzuki, H.; Yokoyama, H.; Kamechara, N.; Tsubone, K.; Tanisawa, H.; Sugiki, H.

    1990-01-01

    This paper reports the transmission characteristics of glass/ceramic composite (borosilicate glass/alumina) and alumina multilayer structures examined. The triplate stripline formed in the glass/ceramic multilayer shows low conductor and dielectric loss. Alumina multilayer, however, has twice the transmission loss at 10 GHz, because the resistivity of W in the alumina multilayer is higher than the Cu in the glass/ceramic multilayer. Crosstalk between striplines in the glass/ceramics is less than -80 dB up to 11 GHz and 9 GHz for alumina

  19. Microwave-assisted brazing of alumina ceramics for electron tube ...

    Indian Academy of Sciences (India)

    Vickers microhardness measurement indicated reliable joint performance for the microwave-assisted brazed joints during ... Alumina ceramics are used in wide range of applications due to their .... temperature were recorded by DAQSOFT software in a sep- .... Tubes: Design and Development Capabilities (MTDDC)',.

  20. State of the art: alumina ceramics for energy applications

    International Nuclear Information System (INIS)

    Hauth, W.E.; Stoddard, S.D.

    1978-01-01

    Prominent ceramic raw materials and products manufacturers were surveyed to determine the state of the art for alumina ceramic fabrication. This survey emphasized current capabilities and limitations for fabrication of large, high-density, high-purity, complex shapes. Some directions are suggested for future needs and development

  1. Multifunctional substrates of thin porous alumina for cell biosensors

    KAUST Repository

    Toccafondi, Chiara; Thorat, Sanjay B.; La Rocca, Rosanna; Scarpellini, Alice; Salerno, Marco; Dante, Silvia; Das, Gobind

    2014-01-01

    We have fabricated anodic porous alumina from thin films (100/500 nm) of aluminium deposited on technological substrates of silicon/glass, and investigated the feasibility of this material as a surface for the development of analytical biosensors aiming to assess the status of living cells. To this goal, porous alumina surfaces with fixed pitch and variable pore size were analyzed for various functionalities. Gold coated (about 25 nm) alumina revealed surface enhanced Raman scattering increasing with the decrease in wall thickness, with factor up to values of approximately 104 with respect to the flat gold surface. Bare porous alumina was employed for micro-patterning and observation via fluorescence images of dye molecules, which demonstrated the surface capability for a drug-loading device. NIH-3T3 fibroblast cells were cultured in vitro and examined after 2 days since seeding, and no significant (P > 0.05) differences in their proliferation were observed on porous and non-porous materials. The effect on cell cultures of pore size in the range of 50–130 nm—with pore pitch of about 250 nm—showed no significant differences in cell viability and similar levels in all cases as on a control substrate. Future work will address combination of all above capabilities into a single device.

  2. Grafting of alumina on SBA-15: Effect of surface roughness

    Czech Academy of Sciences Publication Activity Database

    Zukal, Arnošt; Šiklová, Helena; Čejka, Jiří

    2008-01-01

    Roč. 24, č. 17 (2008), s. 9837-9842 ISSN 0743-7463 R&D Projects: GA AV ČR KAN100400701 Institutional research plan: CEZ:AV0Z40400503 Keywords : alumina-grafted materials * SBA-15 * Nitrogen adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.097, year: 2008

  3. Macroporous silica–alumina composites with mesoporous walls

    Indian Academy of Sciences (India)

    Macroporous silica–alumina composites with mesopores have been prepared by employing polymethylmethacrylate beads as templates in the presence of the cationic surfactant, N-cetyl-N,N,N-trimethylammonium bromide. The Si/Al ratio in the composites has been varied between 4.5 and 48 and the occurrence of ...

  4. Improving subcritical crack growth resistance for alumina glass dental composite

    NARCIS (Netherlands)

    Zhu, Q.; With, de G.

    2005-01-01

    The improvement of subcritical crack growth (SCG) resistance for alumina glass dental composites was explored in this study. The addition of nitrogen to the glass phases in the composite was found to increase the SCG resistance, where the SCG exponent n increases from 22 for the oxide glass

  5. Electrochemical impedance spectroscopy of nanoporous anodic alumina template

    International Nuclear Information System (INIS)

    Shahzad, K.

    2010-01-01

    Room temperature EIS characterization of nanoporous anodic alumina prepared at 40 V and 60 V has been done in 0.3 M oxalic acid solution. Rapid decrease in impedance was observed for the template prepared at 40 V. EIS study of porous anodic alumina template prepared in 0.3 M oxalic acid has been done in different electrolytes. Templates prepared in 0.3 M sulfuric acid solution were also characterized for comparison. Rapid decrease in the thickness of nonporous anodic film was observed with an increase of aggressiveness of electrolyte. Temperature based systematic study of EIS measurement has been done for porous anodic alumina template at different temperatures. Formation of micropores was observed in the nanoporous anodic alumina film formed on aluminum in 0.3 M oxalic acid solution which accelerates the dissolution rate with increase of measurement temperature. In addition to these, electropolishing behavior of pure aluminum has also been studied in different electrolytes and it was observed that electropolishing conditions prior to anodization are extremely important. (author)

  6. Indentation fatigue in silicon nitride, alumina and silicon carbide ...

    Indian Academy of Sciences (India)

    Unknown

    carbide ceramics. A K MUKHOPADHYAY. Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz.

  7. Synthesis and characterization of hydroxyapatite/alumina ceramic ...

    Indian Academy of Sciences (India)

    39

    In the present work, nano crystalline hydroxyapatite/alumina (HAp-Al2O3) composite was .... powder was dried in hot air oven at 80 °C for 24 hours. ... weekly, and the culture medium was changed twice in a week. 4. Results and Discussion.

  8. Dielectric properties of carbon nanofibre/alumina composites

    Czech Academy of Sciences Publication Activity Database

    Fernandez-Garcia, L.; Suarez, M.; Menéndez, J.L.; Pecharromán, C.; Nuzhnyy, Dmitry; Bovtun, Viktor; Savinov, Maxim; Kempa, Martin; Petzelt, Jan

    2013-01-01

    Roč. 57, JUN (2013), s. 380-387 ISSN 0008-6223 R&D Projects: GA ČR GAP204/12/0232; GA MŠk LD12025 Institutional support: RVO:68378271 Keywords : alumina * carbon nanofibre * dielectric and THz spectroscopy * infrared spectroscopy * percolation threshold Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.160, year: 2013

  9. Capillary condensation in porous alumina observed by positronium lifetime spectroscopy

    International Nuclear Information System (INIS)

    Ivanov, Eugeniu; Vata, Ion; Toderian, Stefan; Dudu, Dorin; Rusen, Ion; Stefan, Nitisor

    2008-01-01

    The PALS method based on time distribution measurements has been used to study capillary condensation of different gases adsorbed in microporous alumina powder. The isotherms exhibit features which are associated with a shifted gas-liquid transition. The sorption and desorption processes are irreversible presenting a hysteresis effect. Suggestions on some new aspects of the capillary condensation dynamics are made

  10. Synthesis of Gamma-Alumina from Kankara Kaolin as Potential ...

    African Journals Online (AJOL)

    In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment ...

  11. Multifunctional substrates of thin porous alumina for cell biosensors

    KAUST Repository

    Toccafondi, Chiara

    2014-02-27

    We have fabricated anodic porous alumina from thin films (100/500 nm) of aluminium deposited on technological substrates of silicon/glass, and investigated the feasibility of this material as a surface for the development of analytical biosensors aiming to assess the status of living cells. To this goal, porous alumina surfaces with fixed pitch and variable pore size were analyzed for various functionalities. Gold coated (about 25 nm) alumina revealed surface enhanced Raman scattering increasing with the decrease in wall thickness, with factor up to values of approximately 104 with respect to the flat gold surface. Bare porous alumina was employed for micro-patterning and observation via fluorescence images of dye molecules, which demonstrated the surface capability for a drug-loading device. NIH-3T3 fibroblast cells were cultured in vitro and examined after 2 days since seeding, and no significant (P > 0.05) differences in their proliferation were observed on porous and non-porous materials. The effect on cell cultures of pore size in the range of 50–130 nm—with pore pitch of about 250 nm—showed no significant differences in cell viability and similar levels in all cases as on a control substrate. Future work will address combination of all above capabilities into a single device.

  12. Indentation fatigue in silicon nitride, alumina and silicon carbide ...

    Indian Academy of Sciences (India)

    Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 m and 25 m, and a sintered silicon carbide (SSiC) are reported. The RIF experiments were conducted using a Vicker's ...

  13. Fabrication of an alumina torus for thermonuclear fusion containment

    International Nuclear Information System (INIS)

    Hauth, W.E.; Blake, R.D.; Dickinson, J.M.; Rutz, H.L.; Stoddard, S.D.

    1978-05-01

    A 235-cm-diam torus has been fabricated for plasma containment during thermonuclear fusion experiments. This 30-cm-diam torus consists of sixty 99.5%-alumina segments, 80% of which are assembled by forming vacuum-tight ceramic-to-ceramic seals. Selection of sealing materials and techniques are discussed

  14. Synthesis and textural evolution of alumina particles with mesoporous structures

    International Nuclear Information System (INIS)

    Liu Xun; Peng Tianyou; Yao Jinchun; Lv Hongjin; Huang Cheng

    2010-01-01

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous γ-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl - in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into γ-Al 2 O 3 particles with mesostructures after further calcination at 1173 K, whereas coexisting SO 4 2- can promote above morphology evolution and then transformed into γ-Al 2 O 3 nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m 2 g -1 even after calcinations at 1173 K. - Graphical abstract: Co-existing Cl - is beneficial for the formation of γ-alumina nanoparticles with mesostructures during the precipitation process. Interparticle and intraparticle mesopores can be derived from acidic solution and near neutral solution, respectively.

  15. Controlled growth of single nanowires within a supported alumina template

    DEFF Research Database (Denmark)

    Vlad, A.; Mátéfi-Tempfli, M.; Faniel, S.

    2006-01-01

    A simple technique for fabricating single nanowires with well-defined position is presented. The process implies the use of a silicon nitride mask for selective electrochemical growth of the nanowires in a porous alumina template. We show that this method allows the realization of complex nanowire...

  16. Study on stability of labeled yttrium-90 with lipiodol by chemical extraction for liver cancer

    International Nuclear Information System (INIS)

    Mu, P.Y.; Jiang, X.L.; Chen, J.; Zhu, Y.J.

    2005-01-01

    Liver cancer, particularly hepatocellular carcinoma, is one of the most common malignant diseases in many developed and developing countries. It is also one of the most common diseases endangering the people's lives and health heavily. Surgery is very effective in early-stage patients. Unfortunately, there is less than 10% of the patients with hepatocellular carcinoma fitting for surgical therapy. Instead of surgical therapy, other methods are considered for patients in whom surgery may not work well. Systemic administration of chemotherapeutic agents is not often considered in liver cancer patients, due to discouraging result and adverse side effects. Also, hepatocellular carcinoma is not keen on usual radioactive therapy. However, method of inner interventional radioactive nuclide is a potential way to cure liver tumors. Hepatocellular carcinoma would be cured with inner interventional radioactive nuclide, which is a hot topic in experimental research on hepatocellular carcinoma at home and abroad. The purpose of the study is to label Yttrium-90 with lipiodol by means of the chemical extraction method and research the stability of labeled Yttrium-90 ( 90 Y-P204-Lipiodol) in serum of a newly-born cattle and human's blood. We chose to label steady yttrium with lipiodol, because radioactive yttrium has great nuclear character for liver cancer, yttrium-90 can eradiate pure β radial, and it's half time is 64 hours. Average energy of it is 0.93 Mev, the highest energy is 2.27 Mev. Yttrium-90 can be labeled with lipiodol by means of the chemical extraction method, which is mature in chemical techniques, combined with method of radioactive nuclide labeled in. nuclear medicine. At first, yttrium-90 is extracted in certain condition(pH, temperature, whisk time, whisk frequency, etc ) after adding yttrium-90 solution. We use some distilled water to balance the labeled organic phase twice, and test the stability of labeled yttrium-90 in serum of a newly-born cattle and

  17. Application of various types of alumina and nano--alumina sulfuric acid in the synthesis of α-aminonitriles derivatives: comparative study

    Directory of Open Access Journals (Sweden)

    A. Teimouri

    2014-09-01

    Full Text Available An efficient and green protocol for the synthesis of α-aminonitrile derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanide has been developed using natural alumina, alumina sulfuric acid (ASA, nano-g-alumina, nano-g-alumina sulfuric acid (nano-g-ASA under microwave irradiation and solvent-free conditions. The advantages of methods are short reaction times, high yields, milder conditions and easy work up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. DOI: http://dx.doi.org/10.4314/bcse.v28i3.13

  18. Superhydrophilicity of novel anodic alumina nanofibers films and their formation mechanism

    Science.gov (United States)

    Peng, Rong; Yang, Wulin; Fu, Licai; Zhu, Jiajun; Li, Deyi; Zhou, Lingping

    2017-06-01

    A novel anodic alumina nanofibers structure, which is different from the traditional porous anodic structure, has been quickly fabricated via anodizing in a new electrolyte, pyrophosphoric acid. The effects of the solution concentration and the anodizing time on the formation of the anodic alumina nanofibers were analyzed. The results show that the nanostructure of anodic alumina can change to the nanofiber oxide from the porous oxide by increasing the solution concentration. Prolonging the anodizing time is beneficial to obtain alumina nanofibers at high solution concentration. Growth behavior of the alumina nanofibers was also discussed by scanning electron microscopy observations. Owing to the unique hexagonal structure of anodic alumina as well as the preferential chemical dissolution between the porous anodic alumina and the anodic alumina nanotips, the slightly soluble anodic alumina nanotips could form novel alumina nanofibers during anodizing. The results show that the nanofibers-covered aluminum surface exhibits superhydrophilic property, with a near-zero water contact angle. Such alumina nanofibers with superhydrophilic property could be used for various potential applications.

  19. Nanostructural characterization of large-scale porous alumina fabricated via anodizing in arsenic acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Akiya, Shunta; Kikuchi, Tatsuya, E-mail: kiku@eng.hokudai.ac.jp; Natsui, Shungo; Suzuki, Ryosuke O.

    2017-05-01

    Highlights: • Anodic porous alumina was formed in an arsenic acid solution. • Potential difference (voltage) anodizing at 340 V was achieved. • The porous alumina was slightly ordered under the appropriate conditions. • Pore sealing behavior was not observed in boiling distilled water. • The porous alumina exhibits a white photoluminescence emission under UV irradiation. - Abstract: Anodizing of aluminum in an arsenic acid solution is reported for the fabrication of anodic porous alumina. The highest potential difference (voltage) without oxide burning increased as the temperature and the concentration of the arsenic acid solution decreased, and a high anodizing potential difference of 340 V was achieved. An ordered porous alumina with several tens of cells was formed in 0.1–0.5 M arsenic acid solutions at 310–340 V for 20 h. However, the regularity of the porous alumina was not improved via anodizing for 72 h. No pore sealing behavior of the porous alumina was observed upon immersion in boiling distilled water, and it may be due to the formation of an insoluble complex on the oxide surface. The porous alumina consisted of two different layers: a hexagonal alumina layer that contained arsenic from the electrolyte and a pure alumina honeycomb skeleton. The porous alumina exhibited a white photoluminescence emission at approximately 515 nm under UV irradiation at 254 nm.

  20. Effects of Processing Temperatures of Nickel Plating on Capacitance Density of Alumina Film Capacitor.

    Science.gov (United States)

    Jeong, Myung-Sun; Ju, Byeong-Kwon; Lee, Jeon-Kook

    2015-06-01

    We observed the effects of nickel plating temperatures for controlling the surface morphologies of the deposited nickel layers on the alumina nano-pores. The alumina nano-channels were filled with nickel at various processing temperatures of 60-90 degrees C. The electrical properties of the alumina film capacitors were changed with processing temperatures. The electroless nickel plating (ENP) at 60 degrees C improved the nickel penetration into the alumina nano-channels due to the reduced reaction rate. Nickel layers are uniformly formed on the high aspect ratio alumina pores. Due to the uniform nickel electrode, the capacitance density of the alumina film capacitors is improved by the low leakage current, dissipation factor and equivalent series resistance. Alumina film capacitors made by ENP at 60 degrees C had a high capacitance density of 160 nF/cm2.

  1. Synthesis and structural evaluation of freeze-cast porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Douglas F., E-mail: souzadf@outlook.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nunes, Eduardo H.M., E-mail: eduardohmn@gmail.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Pimenta, Daiana S.; Vasconcelos, Daniela C.L. [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nascimento, Jailton F.; Grava, Wilson [Petrobras/CENPES, Avenida Horácio Macedo 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ CEP:21941-915 (Brazil); Houmard, Manuel [Department of Materials Engineering and Civil Construction, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 1, sala 3304 (Brazil); Vasconcelos, Wander L., E-mail: wlv@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil)

    2014-10-15

    In this work we fabricated alumina samples by the freeze-casting technique using tert-butanol as the solvent. The prepared materials were examined by scanning electron microscopy and X-ray microtomography. Next, they were coated with sol–gel silica films by dip-coating. Permeability tests were carried out in order to assess the permeation behavior of the materials processed in this study. We observed that the sintering time and alumina loading showed a remarkable effect on both the structural properties and flexural strength of the freeze-cast samples. Nitrogen adsorption tests revealed that the silica prepared in this study exhibited a microporous structure. It was observed that the presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance by about one order of magnitude. Because of the similar kinetic diameters of nitrogen and carbon dioxide, the CO{sub 2}/N{sub 2} system showed a separation efficiency that was lower than that observed for the He/CO{sub 2} and He/N{sub 2} systems. We noticed that increasing the feed pressure improved the separation capacity of the obtained materials. - Highlights: • Porous alumina samples obtained by the freeze-casting technique • Microporous silica coating prepared by a simple sol–gel dip-coating methodology • Samples examined by SEM, μ-CT, and nitrogen sorption tests • Mechanical tests were carried out in the freeze-cast samples. • The presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance.

  2. Optical performance of hybrid porous silicon-porous alumina multilayers

    Science.gov (United States)

    Cencha, L. G.; Antonio Hernández, C.; Forzani, L.; Urteaga, R.; Koropecki, R. R.

    2018-05-01

    In this work, we study the optical response of structures involving porous silicon and porous alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these porous materials can be used to exploit its distinguishing features, i.e., high transparency of alumina and high refractive index of porous silicon. We assembled hybrid microcavities with a central porous alumina layer between two porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with porous silicon or porous alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal porous silicon microcavity at this wavelength.

  3. Advanced morphological analysis of patterns of thin anodic porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Toccafondi, C. [Istituto Italiano di Tecnologia, Department of Nanophysics, Via Morego 30, Genova I 16163 (Italy); Istituto Italiano di Tecnologia, Department of Nanostructures, Via Morego 30, Genova I 16163 (Italy); Stępniowski, W.J. [Department of Advanced Materials and Technologies, Faculty of Advanced Technologies and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland); Leoncini, M. [Istituto Italiano di Tecnologia, Department of Nanostructures, Via Morego 30, Genova I 16163 (Italy); Salerno, M., E-mail: marco.salerno@iit.it [Istituto Italiano di Tecnologia, Department of Nanophysics, Via Morego 30, Genova I 16163 (Italy)

    2014-08-15

    Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for the thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing.

  4. Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina)

    International Nuclear Information System (INIS)

    Rouquerol, J.

    1964-11-01

    This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina α-trihydrate Al(OH) 3 and beryllium α-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author) [fr

  5. Separation of yttrium from strontium in the aqueous phase of the water/nitrobenzene system

    Czech Academy of Sciences Publication Activity Database

    Vaňura, P.; Makrlík, E.; Vobecký, Miloslav

    2002-01-01

    Roč. 253, č. 1 (2002), s. 171-172 ISSN 0236-5731 Institutional research plan: CEZ:AV0Z4031919 Keywords : stroncium * yttrium * separation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.502, year: 2002

  6. Separation of microamounts of yttrium from strontium in the two-phase water/nitrobenzene system

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Vaňura, P.; Vobecký, Miloslav

    2002-01-01

    Roč. 253, č. 1 (2002), s. 153-155 ISSN 0236-5731 Institutional research plan: CEZ:AV0Z4031919 Keywords : separation * stroncium * yttrium Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.502, year: 2002

  7. Separation of yttrium from strontium in the aqueous phase of the water/nitrobenzene extraction system

    Czech Academy of Sciences Publication Activity Database

    Vaňura, P.; Makrlík, E.; Vobecký, Miloslav

    2003-01-01

    Roč. 256, č. 1 (2003), s. 171-172 ISSN 0236-5731 R&D Projects: GA MŠk LN00B084 Institutional research plan: CEZ:AV0Z4031919; CEZ:MSM 230000009 Keywords : extraction * strontium * yttrium Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.472, year: 2003

  8. Reaction scheme of partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia

    NARCIS (Netherlands)

    Zhu, J.J.; van Ommen, J.G.; Lefferts, Leonardus

    2004-01-01

    The partial oxidation of methane to synthesis gas over yttrium-stabilized zirconia (YSZ) was studied with in situ FTIR and both steady-state and transient experiments. The four major products, CO, H2, CO2, and H2O, are primary products of CPOM over YSZ. Besides these major products and traces of

  9. Adducts compounds of lanthanides (III) trifluoreacetates and yttrium and the N,N - dimenthylformamide

    International Nuclear Information System (INIS)

    Silva, M. das G. da.

    1983-01-01

    Some studies on lanthanides, f transition elements, and yttrium are presented. Adducts of lanthanides trifluoroacetates and N,N -dimethylformamide are described. The characterization of complexes from elementar analysis, conductance measurements, X-ray patterns, vibrational, electronics and fluorescence spectra are analysed. (M.J.C.) [pt

  10. Yttrium deposition on mesoporous TiO2: textural design and UV ...

    Indian Academy of Sciences (India)

    The mesoporous yttrium-doped TiO2 substrates prepared in this research work operate ... bond lengths in the nanoparticles (0.192 and 0.196 nm).18. Additionally ...... Fisicoquímica de Materiales Mesoporosos' (UAM-I CA-31. Fisicoquímica de ...

  11. Monte carlo simulations of Yttrium reaction rates in Quinta uranium target

    Directory of Open Access Journals (Sweden)

    Suchopár M.

    2017-01-01

    Full Text Available The international collaboration Energy and Transmutation of Radioactive Waste (E&T RAW performed intensive studies of several simple accelerator-driven system (ADS setups consisting of lead, uranium and graphite which were irradiated by relativistic proton and deuteron beams in the past years at the Joint Institute for Nuclear Research (JINR in Dubna, Russia. The most recent setup called Quinta, consisting of natural uranium target-blanket and lead shielding, was irradiated by deuteron beams in the energy range between 1 and 8 GeV in three accelerator runs at JINR Nuclotron in 2011 and 2012 with yttrium samples among others inserted inside the setup to measure the neutron flux in various places. Suitable activation detectors serve as one of possible tools for monitoring of proton and deuteron beams and for measurements of neutron field distribution in ADS studies. Yttrium is one of such suitable materials for monitoring of high energy neutrons. Various threshold reactions can be observed in yttrium samples. The yields of isotopes produced in the samples were determined using the activation method. Monte Carlo simulations of the reaction rates leading to production of different isotopes were performed in the MCNPX transport code and compared with the experimental results obtained from the yttrium samples.

  12. Structural differences of half-sandwich complexes of scandium and yttrium containing bulky substituents

    Czech Academy of Sciences Publication Activity Database

    Fridrichová, Adéla; Růžička, A.; Lamač, Martin; Horáček, Michal

    2017-01-01

    Roč. 76, FEB 2017 (2017), s. 62-66 ISSN 1387-7003 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : scandium * yttrium * half-sandwich Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.640, year: 2016

  13. Monte carlo simulations of Yttrium reaction rates in Quinta uranium target

    Science.gov (United States)

    Suchopár, M.; Wagner, V.; Svoboda, O.; Vrzalová, J.; Chudoba, P.; Tichý, P.; Kugler, A.; Adam, J.; Závorka, L.; Baldin, A.; Furman, W.; Kadykov, M.; Khushvaktov, J.; Solnyshkin, A.; Tsoupko-Sitnikov, V.; Tyutyunnikov, S.; Bielewicz, M.; Kilim, S.; Strugalska-Gola, E.; Szuta, M.

    2017-03-01

    The international collaboration Energy and Transmutation of Radioactive Waste (E&T RAW) performed intensive studies of several simple accelerator-driven system (ADS) setups consisting of lead, uranium and graphite which were irradiated by relativistic proton and deuteron beams in the past years at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The most recent setup called Quinta, consisting of natural uranium target-blanket and lead shielding, was irradiated by deuteron beams in the energy range between 1 and 8 GeV in three accelerator runs at JINR Nuclotron in 2011 and 2012 with yttrium samples among others inserted inside the setup to measure the neutron flux in various places. Suitable activation detectors serve as one of possible tools for monitoring of proton and deuteron beams and for measurements of neutron field distribution in ADS studies. Yttrium is one of such suitable materials for monitoring of high energy neutrons. Various threshold reactions can be observed in yttrium samples. The yields of isotopes produced in the samples were determined using the activation method. Monte Carlo simulations of the reaction rates leading to production of different isotopes were performed in the MCNPX transport code and compared with the experimental results obtained from the yttrium samples.

  14. Influence of neodymium-doping on structure and properties of yttrium aluminium garnet

    DEFF Research Database (Denmark)

    Zhang, X.D.; He, W.; Yue, Yuanzheng

    2013-01-01

    We study the impact of the Nd-doping on the grain formation, the crystal structure, and the fluorescence of the Yttrium Aluminum Garnet (YAG). The results show that Nd-doping leads to the YAG lattice expansion and distortion, and hence to an increase in defect concentration. This is attributed to...

  15. Thermal decomposition of double selenates of lanthanides (III), yttrium (III) and ammonium

    International Nuclear Information System (INIS)

    Crespi, M.S.

    1989-01-01

    Double selenates of lanthanides, yttrium and ammonium were prepared by treating mixtures of simple selenates with equimolar amounts and then dried in a vacuum desiccator containing anhydrous calcium chloride, protected from light. The compounds were studied using the conventional analytical methods such as infrared absorption spectra, X-ray diffraction, differential thermal analysis (DTA), and thermogravimetry (TG). (author)

  16. Optimization of the personnel radiation protection during the treatment by antibodies labelled by yttrium 90

    International Nuclear Information System (INIS)

    Legrand, J.; Prangere, T.; Cougnenc, O.; Leleu, C.; Huglo, D.; Morschhauser, F.

    2007-01-01

    Beyond the acquired experience limiting the exposure time, measures of adequate radiation protection allow to reduce the doses of surface received to extremities by the personnel participating to the preparation of treatments by antibodies labelled by yttrium 90. (N.C.)

  17. High-pressure structural study of yttrium monochalcogenides from experiment and theory

    DEFF Research Database (Denmark)

    Vaitheeswaran, G.; Kanchana, V.; Svane, A.

    2011-01-01

    High-pressure powder x-ray diffraction experiments using synchrotron radiation are performed on the yttrium monochalcogenides YS, YSe, and YTe up to a maximum pressure of 23 GPa. The ambient NaCl structure is stable throughout the pressure range covered. The bulk moduli are determined to be 93, 82...

  18. Yttrium recovery from primary and secondary sources: A review of main hydrometallurgical processes

    Energy Technology Data Exchange (ETDEWEB)

    Innocenzi, Valentina, E-mail: valentina.innocenzi1@univaq.it [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy); De Michelis, Ida [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy); Kopacek, Bernd [SAT, Austrian Society for Systems Engineering and Automation, Gurkasse 43/2, A-1140 Vienna (Austria); Vegliò, Francesco [Department of Industrial Engineering, of Information and Economy, University of L’Aquila, Via Giovanni Gronchi 18, Zona industriale di Pile, 67100 L’Aquila (Italy)

    2014-07-15

    Highlights: • Review of the main hydrometallurgical processes to recover yttrium. • Recovery of yttrium from primary sources. • Recovery of yttrium from e-waste and other types of waste. - Abstract: Yttrium is important rare earths (REs) used in numerous fields, mainly in the phosphor powders for low-energy lighting. The uses of these elements, especially for high-tech products are increased in recent years and combined with the scarcity of the resources and the environmental impact of the technologies to extract them from ores make the recycling waste, that contain Y and other RE, a priority. The present review summarized the main hydrometallurgical technologies to extract Y from ores, contaminated solutions, WEEE and generic wastes. Before to discuss the works about the treatment of wastes, the processes to retrieval Y from ores are discussed, since the processes are similar and derived from those already developed for the extraction from primary sources. Particular attention was given to the recovery of Y from WEEE because the recycle of them is important not only for economical point of view, considering its value, but also for environmental impact that this could be generated if not properly disposal.

  19. Separation and purification of gadolinium and others rare earths, and yttrium

    International Nuclear Information System (INIS)

    Awwal, M.A.; Filgueiras, S.A.C.

    1988-01-01

    The experimental works in laboratories for developing a solvent extraction process with the purpose of gadolinium separation and purification, and secondarily samarium, europium, lanthanum and yttrium are described. Using as solvent di-2-ethylhexylphosphoric acid (DEHPA) a preliminary flow chart for separation for these elements are developed. (author)

  20. Extraction of Alumina from Red Mud for Synthesis of Mesoporous Alumina by Adding CTABr as Mesoporous Directing Agent

    Directory of Open Access Journals (Sweden)

    Eka Putra Ramdhani

    2018-05-01

    Full Text Available Mines in Bintan were producing bauxite for many years. The production process of bauxite to alumina produced much red mud. From X-ray Fluorescence (XRF, alumina content on Bintan’s red mud was 28.87 wt.%. This research was studying on the extraction alumina from red mud with reduction of hematite (Fe2O3 and desilication processes. After extraction process alumina was collected about 52.89 wt.%. Synthesis of mesoporous alumina from red mud using sol-gel method at the room temperature for 72 h with cetyltrimethylammonium bromide (CTABr as mesoporous directing agent. The CTABr/Al-salt ratio, i.e. 1.57; 4.71 and 7.85 with the sample code of AMC-1, AMC-3, AMC-5, respectively. The product was calcined at 550 °C for 6 h. The synthesized materials were characterized by X-ray Diffraction (XRD, scanning electron microscopy-energy dispersive X-ray (SEM-EDX, transmission electron microscopy (TEM, and N2 adsorption-desorption techniques. XRD pattern of AMC-1, AMC-3, and AMC-5 showed that all synthesized materials have amorphous phase. The morphology were wormhole aggregate that were showed by SEM and TEM characterization. N2 adsorption-desorption characterization showed the distribution of pore size of about 3.2 nm. The highest surface area and pore volume were obtained in solid-solid ratio CTABr/GM-AL by 1.57 (AMC-1 i.e. 241 m2/g and 0.107 cm3/g, respectively.

  1. Characterization of metallized alumina: properties. [Diamonite P-3142-1, Wesgo Al-500 alumina ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Swearengen, J.C.; Burchett, O.L., Gieske, J.H.

    1976-12-01

    The effects of metallizing and brazing on the mechanical properties of Diamonite P-3142-1 and Wesgo A1-500 alumina ceramics were evaluated. The information was required for analytical prediction of the performance of ceramic-to-metal joints formed by the metallize-braze process. Residual stresses and fracture strengths were monitored before and after metallizing treatments; micromechanical modelling and surface acoustic wave experiments were utilized to determine density, thermal expansion and elastic moduli within the metallized region of the ceramics. It was observed that the metallizing elements penetrate the ceramics to a depth of about 005 ..mu..m and measurably modify the properties to a depth of about 300 ..mu..m. The moduli and density are increased approximately five percent within the penetration zone. The thermal expansion coefficients are not modified significantly by metallizing; the warping which occurs during metallizing results from microstructural changes within the ceramics and not differential thermal contraction. Fracture toughness of the Diamonite ceramic is greater than that of the Wesgo, although the metallizing treatments increase the toughness of each. Fracture strength of the Diamonite was degraded on the metallized surface, whereas the strength of the Wesgo was essentially unchanged by metallizing. Macroscopic compressive residual stresses, which exist at the surfaces of the ceramics, do not significantly affect the fracture strengths. The implications of these results for calculations of joint performance are discussed.

  2. Pemanfaatan serat silicon carbon dan partikel alumina pada matrik aluminium untuk meningkatkan sifat mekanis material komposit

    Directory of Open Access Journals (Sweden)

    Ketut Suarsana

    2017-03-01

    previous treatment. Indonesia has the potential of naturalresources potential, especially as fiber from plant sources also include metals aluminum (bauxite from fossils. This material canbe used for the needs of the industry as the manufacture of composite base Aluminium and as a reinforcement in the form offibers or particles of alumina. The method of making Aluminum Matrix Composites (AMC with a powder metallurgy process atthe compression force / compaction 2.5 tons using a hydraulic press equipment, holding time 15 minutes, and the treatmentprocess in the variation of the composition by weight (%wt. Variations in the composition of the fiber reinforcement SiliconCarbon (SiC and Al2O3 (alumina on a matrix Aluminium is: 30% SiC + 0% Al203, 27% SiC + 3% Al203, 24% SiC + 6% Al203 and21% SiC + 9% Al203 with a matrix of 70% Al, on condition tempertaur 500oC, 550oC and 600oC. After the composite material isformed, tested for mechanical properties due to the influence of variations in composition between matrix and reinforcement incomposites. Characteristics test performed in the laboratory to knowing strength and hardness properties of composite materials.Furthermore sought the relationship between the nature of each composition fiber reinforcement and an Al2O3 forming SiCcomposites made to know the benefits of reinforcing fibers and particles of alumina.Keywords: Strength, hardness, SiC fibers and Al2O3

  3. Element selective X-ray magnetic circular and linear dichroisms in ferrimagnetic yttrium iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Rogalev, A. [European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex (France); Goulon, J. [European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex (France)], E-mail: goulon@esrf.fr; Wilhelm, F. [European Synchrotron Radiation Facility (ESRF), B.P. 220, F-38043 Grenoble Cedex (France); Brouder, Ch. [Institut de Mineralogie et de Physique des Milieux Condenses, UMR-CNRS 7590, Universite Paris VI-VII, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Yaresko, A. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Ben Youssef, J.; Indenbom, M.V. [Laboratoire de Magnetisme de Bretagne, CNRS FRE 2697, UFR Sciences et Techniques, F-29328 Brest Cedex (France)

    2009-12-15

    X-ray magnetic circular dichroism (XMCD) was used to probe the existence of induced magnetic moments in yttrium iron garnet (YIG) films in which yttrium is partly substituted with lanthanum, lutetium or bismuth. Spin polarization of the 4d states of yttrium and of the 5d states of lanthanum or lutetium was clearly demonstrated. Angular momentum resolved d-DOS of yttrium and lanthanun was shown to be split by the crystal field, the two resolved substructures having opposite magnetic polarization. The existence of a weak orbital moment involving the 6p states of bismuth was definitely established with the detection of a small XMCD signal at the Bi M{sub 1}-edge. Difference spectra also enhanced the visibility of subtle changes in the Fe K-edge XMCD spectra of YIG and {l_brace}Y, Bi{r_brace}IG films. Weak natural X-ray linear dichroism signatures were systematically observed with all iron garnet films and with a bulk YIG single crystal cut parallel to the (1 1 1) plane: this proved that, at room temperature, the crystal cannot satisfy all requirements of perfect cubic symmetry (space group: Ia3-bar d), crystal distortions preserving at best trigonal symmetry (R3-bar or R3m). For the first time, a very weak X-ray magnetic linear dichroism (XMLD) was also measured in the iron K-edge pre-peak of YIG and revealed the presence of a tiny electric quadrupole moment in the ground-state charge distribution of iron atoms. Band-structure calculations carried out with fully relativistic LMTO-LSDA methods support our interpretation that ferrimagnetically coupled spins at the iron sites induce a spin polarization of the yttrium d-DOS and reproduce the observed crystal field splitting of the XMCD signal.

  4. Element selective X-ray magnetic circular and linear dichroisms in ferrimagnetic yttrium iron garnet films

    International Nuclear Information System (INIS)

    Rogalev, A.; Goulon, J.; Wilhelm, F.; Brouder, Ch.; Yaresko, A.; Ben Youssef, J.; Indenbom, M.V.

    2009-01-01

    X-ray magnetic circular dichroism (XMCD) was used to probe the existence of induced magnetic moments in yttrium iron garnet (YIG) films in which yttrium is partly substituted with lanthanum, lutetium or bismuth. Spin polarization of the 4d states of yttrium and of the 5d states of lanthanum or lutetium was clearly demonstrated. Angular momentum resolved d-DOS of yttrium and lanthanun was shown to be split by the crystal field, the two resolved substructures having opposite magnetic polarization. The existence of a weak orbital moment involving the 6p states of bismuth was definitely established with the detection of a small XMCD signal at the Bi M 1 -edge. Difference spectra also enhanced the visibility of subtle changes in the Fe K-edge XMCD spectra of YIG and {Y, Bi}IG films. Weak natural X-ray linear dichroism signatures were systematically observed with all iron garnet films and with a bulk YIG single crystal cut parallel to the (1 1 1) plane: this proved that, at room temperature, the crystal cannot satisfy all requirements of perfect cubic symmetry (space group: Ia3-bar d), crystal distortions preserving at best trigonal symmetry (R3-bar or R3m). For the first time, a very weak X-ray magnetic linear dichroism (XMLD) was also measured in the iron K-edge pre-peak of YIG and revealed the presence of a tiny electric quadrupole moment in the ground-state charge distribution of iron atoms. Band-structure calculations carried out with fully relativistic LMTO-LSDA methods support our interpretation that ferrimagnetically coupled spins at the iron sites induce a spin polarization of the yttrium d-DOS and reproduce the observed crystal field splitting of the XMCD signal.

  5. Tattoo removal by Q-switched yttrium aluminium garnet laser: client satisfaction.

    Science.gov (United States)

    Hutton Carlsen, K; Esmann, J; Serup, J

    2017-05-01

    Tattoo removal by Q-switched yttrium aluminium garnet (YAG) lasers is golden standard; however, clients' satisfaction with treatment is little known. To determine clients' satisfaction with tattoo removal. One hundred and fifty-four tattoo removal clients who had attended the private clinic 'Centre for Laser Surgery', Hellerup, Denmark, from 2001 to 2013 completed a questionnaire concerning outcome expectations, level of pain experiences and satisfaction with tattoo removal. The laser surgeon and his team were blinded from data handling. The study design included a minimum 2-year postlaser treatment observation period from 2013 to 2015. Overall, clients were satisfied with their laser treatment; 85% assessed their treatment and results to be acceptable to superb, while 15% assessed their treatment and results to be inferior to unacceptable. Effectiveness relative to colour of tattoo on a scale from 0 (no effect) to 10 (complete removal) scored a mean of blue 9.5, black 9.4, yellow 8.9, red 8.8 and green 6.5. Clients were dissatisfied with green pigment remnants, which could mimic bruising. One hundred and twenty-nine clients (84%) experienced moderate to extreme pain during treatment. Twenty-eight (20%) developed minor scarring. There were many reasons for tattoo removal; e.g. stigmatisation (33%), conspicuousness (29%) and poor artistic quality (22%). One hundred and two clients had expected complete removal of tattoos without a blemish, expectations that were only partly fulfilled. During the treatment period, clients adjusted expectations and adapted more realistic views of outcomes. The majority of clients were satisfied with Q-switched YAG laser removal of tattoos despite high pretreatment expectations which were only partly met. The study supports YAG lasers for tattoo removal as acceptable therapy of today, with room for new approaches. © 2017 European Academy of Dermatology and Venereology.

  6. Surface study of nano-template anodic porous alumina pre-irradiated by ArF laser

    International Nuclear Information System (INIS)

    Jaleh, B.; Saramad, S.; Farshchi-Tabrizi, M.

    2009-01-01

    Nano-porous alumina membranes have widely used as matrix for the fabrication of nanomaterials for many applications including quantum-dot arrays, magnetic storage devices and composites for catalysis, due to their remarkable hardness, thermal and anti corrupted stability, uniform pore size and high pore density. In this experiment three sets of aluminum samples were chosen for fabrication nano-porous anodic alumina. One set has select for laser cleaning before chemical treatment and the two others with and without chemical treatment without laser irradiation. Anodic aluminum oxide (AAO) films were characterized with Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) micrograph and the SEM results were analyzed by Linear-Angular Fast Fourier Transform (LA-FFT) technique to investigate the arrangement and ordering of pores. According to these results the laser irradiated sample has much better regularity in comparison with the usual one.

  7. Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte

    Science.gov (United States)

    Porta-i-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J.; Marsal, Lluis F.

    2016-08-01

    Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate.

  8. A study on heat transfer characteristics of spherical and fibrous alumina nanofluids

    International Nuclear Information System (INIS)

    Kim, Chang Kyu; Lee, Gyoung-Ja; Rhee, Chang Kyu

    2012-01-01

    Highlights: ► Spherical and fibrous alumina nanoparticles were prepared by pulsed wire evaporation and hydrolysis methods. ► Fibrous alumina nanofluid exhibited higher thermal conductivity enhancement than spherical one due to entangled structure of nanofibers with high aspect-ratio. ► Decreasing rate of viscosity with temperature for fibrous alumina nanofluid was much larger than that for spherical one. - Abstract: Ethylene glycol based nanofluids containing spherical/fibrous alumina nanoparticles were synthesized by pulsed wire evaporation and hydrolysis methods. The crystallographic and morphological properties of the prepared nanoparticles were analyzed by X-ray diffraction, nitrogen gas adsorption and transmission electron microscopy. The average diameter of spherical alumina nanoparticles was about 80 nm and the alumina nanofibers exhibited a high aspect ratio (length/width). The viscosity and thermal conductivity of the spherical/fibrous alumina nanofluids were experimentally measured in the temperature range from 25 to 80 °C. For the fibrous alumina nanofluid, the increase of temperature raised thermal conductivity but lowered viscosity. On the other hand, for the spherical alumina nanofluid, both thermal conductivity and viscosity were decreased with increasing temperature. In particular, the fibrous alumina nanofluid exhibited a higher enhancement of thermal conductivity than the spherical one due to the well-connected structure between entangled nanofibers with high aspect ratio.

  9. Deuterium permeation of amorphous alumina coating on 316L prepared by MOCVD

    International Nuclear Information System (INIS)

    Li Shuai; He Di; Liu Xiaopeng; Wang Shumao; Jiang Lijun

    2012-01-01

    Highlights: ► Deuterium permeation behavior of alumina coating by MOCVD is investigated. ► The as-prepared alumina is amorphous. ► The alumina coating is dense and well adherent to substrate. ► Deuterium permeation rate of alumina coating is 2–3 orders of magnitude lower than martensitic steels. - Abstract: The deuterium permeation behavior of the alumina coating on 316L stainless steel prepared by metal organic chemical vapor deposition (MOCVD) was investigated. The alumina coating was also characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM). It was found that the as-prepared coating consisted of amorphous alumina. This alumina coating had a dense, crack-free and homogeneous morphology. Although the alumina coating was amorphous, effective suppression of deuterium permeation was demonstrated. The deuterium permeability of the alumina coating was 51–60 times less than that of the 316L stainless steel and 153–335 times less than that of the referred low activation martensitic steels at 860–960 K.

  10. Properties of zirconium ceramics and film stabilized by yttrium

    International Nuclear Information System (INIS)

    Korobova, N.

    2004-01-01

    Full text: Unstable zirconium dioxide phase transformation can be eliminated by stabilization of the cubic phase with an addition of a selected alkaline earth or rare-earth oxide. Stabilized ZrO 2 has been widely utilized in various high-temperature refractory applications. These stabilized ZrO 2 -base solid solutions also possess rather unique electrical properties, and as a result have considerable potential as solid electrolytes in galvanic and fuel cells and, possibly, as heating elements in high-temperature furnaces. The complex study of synthesis processes, structure and properties of metal alkoxide organic sols have been developed. These have allowed to create main principles of their formation and to show the practical realization of obtained theoretical and experimental results. The correlation between hydrolysis conditions of (Zr+Y) metal alkoxide sols and synthesis of stable colloid multi-component systems has been established. Systematic research of zirconium and yttrium bi-alkoxide electrophoretic deposition was conducted for the first time. The formation mechanism of electrophoretic deposits has been offered and general scientific principles of the electrophoretic process have been formulated. The model of gel deposits structure was proposed. It has enabled to analyze the main (for example, cluster) effects, which have been exhibited in technological procedure for thin film preparation. The structure investigation of stabilized zirconium dioxide thin films and ceramics has been studied. The researches were based on the comparative analysis of the initial gel microstructure and dried gel by the various drying methods. The new approach for drying of gel electrophoretic deposits was formulated theoretically and experimentally has been proved. The modeling of the aggregate kinetics as a type of 'cluster-cluster' has been proposed like a qualitative description of the process. The data of fractal dimensions of aggregates which have been formed at the

  11. Occupational exposure following Yttrium-90 microspheres SIR therapy

    International Nuclear Information System (INIS)

    Fontaine, P.; Boirie, G.; Dieudonne, A.; Leguludec, D.; Lebtahi, R.; Ben Reguiga, M.

    2015-01-01

    Full text of publication follows. Introduction: Selective Internal Radiation Therapy (SIRT) is a promising technique for solid hepatic neoplasms treatment. SIRT consists in implanting radioactive microspheres (RMS) in targeted hepatic lesions via femoral artery. Two RMS-Therapsheres [glass-microspheres/TSR] and Sir-Spheres [resin-spheres/SSR]- are marketed in the European market, both radiolabeled with Yttrium-90. The objective of this study is to assess occupational exposure for nuclear medicine, radiology and clinical staff involved in Y 90 -RMS preparation and implantation. Materials and methods: The study was conducted on 20 patients treated for Hepato-Cellular Carcinoma: 10 treated with TSR and 10 with SSR. Dose rate (DR, mSv/h) or absorbed doses (mSv) measurements were made during all steps of TSR and SSR handling: sources receipt and unpacking, preparation, transport to radiology, implantation, and patient care. Measurements were made with portable ionization chamber(Babyline/Nardeux), spectrometer(FieldSpect/Aries), digital dosimeter (NED/Unfors) and operational dosimeter (Mk2/Siemens). Values were expressed as mean±SD. Results: patients received of 1.8 GBq to 3.1 GBq of TSR and 0.55 GBq to 2.4 GBq of SSR. TSR were delivered ready-to-use with the prescribed activity. For SSR only one activity was commercially available and shipped (3 GBq at calibration-time)requiring a preparation step to adjust needed activity. DR measured during RMS was 1723 ± 157 μSv/h SSR and 1189 ± 92 μSv/h for TSR. When preparing spheres in radiopharmacy, fingers and whole body doses were respectively 8326 ± 2360 μSv and 12.3 ± 5,2 μSv for Sir-Spheres vs. 33.5 ± 7.8 μSv and 1.1 ± 0.3 μSv for TSR. DR in contact with carrying case during RMS transfer to radiology were 299 ± 102 μSv/h for SSR and 5.3 ± 1.2 μSv/h for TSR. During RMS infusion, radiologist's finger doses were limited to 3.6 ± 1 μSv for SSR and 0.7± 0.3 μSv for TSR. Finally, following RMS

  12. Study of preparation and surface morphology of self-ordered nanoporous alumina; Estudo da preparacao e da morfologia de superficie de alumina nanoporosa auto-organizada

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Elisa Marchezini; Martins, Maximiliano Delany, E-mail: elisamarch@gmail.com, E-mail: MG.mdm@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG. (Brazil); Silva, Ronald Arreguy, E-mail: arregsilva@yahoo.com.br [Centro Universitario de Belo Horizonte (UniBH), Belo Horizonte, MG (Brazil)

    2013-07-01

    Nanoporous alumina is a typical material that exhibits self-ordered nanochannels spontaneously organized in hexagonal shape. Produced by anodizing of metallic aluminum, it has been used as a template for production of materials at the nanoscale. This work aimed to study the preparation of nanoporous alumina by anodic anodizing of metallic aluminum substrates. The nanoporous alumina was prepared following the methodology proposed by Masuda and Fukuda (1995), a two-step method consisting of anodizing the aluminum sample in the potentiostatic mode, removing the layer of aluminum oxide (alumina) formed and then repeat the anodization process under the same conditions as the first anodization. This method produces nanoporous alumina with narrow pore diameter distribution and well-ordered structure. (author)

  13. Electrochemically grown metallic nanocomb structures on nanoporous alumina templates

    International Nuclear Information System (INIS)

    Kaya, Savas; Atar, Erdem

    2011-01-01

    Electrochemical growth of metallic nanocomb structures on anodized alumina templates is described. Nanocombs originate from the orderly growth and merger of very thin (d=15±5 nm) metallic nanowires which do not completely fill much larger pores (d∼100 nm) in the alumina template (t≤3 μm). Instead, the nanowires prefer growing along the inner corners of the hexagonal pores, coalescing into a highly ordered structure as they emerge, resulting a metallic form reminiscent of the topology of the original template. We disclose here the typical processing conditions and the microstructure of this previously unknown material as observed with a scanning electron microscope (SEM) and energy dispersive x-ray (EDX) spectroscopy. It is shown that Au nanocombs have an anomalous EDX spectra and can emit electrons at a field of ∼1 kV/cm.

  14. Health monitoring technology for alumina-fiber-reinforced plastic

    International Nuclear Information System (INIS)

    Aoyama, Hiroshi; Watanabe, Hiroyuki; Terai, Motoaki

    1998-01-01

    Formally, we developed new load-support systems that consists of a biconical, alumina-fiber-reinforced plastic (ERP) structure for the superconducting magnet. Safe operation of the superconducting magnet will be jeopardized if the mechanical condition of the load-support system begins to degrade. One of the factors that evaluate the soundness of the superconducting magnet is the stiffness of the load-support system. Here, it is important to know the relation between the degradation of the stiffness and the growth of defects. For this purpose, firstly, a fatigue test of the load-support system was carried out, and the various defects (matrix cracking and delamination of FRP laminates) were observed during this fatigue testing. Finally, we proposed the application of two non-destructive-evaluation (NDE) methods for the health monitoring of alumina/epoxy load-support systems. (author)

  15. Long-term results of uncemented alumina acetabular implants.

    Science.gov (United States)

    Boehler, M; Knahr, K; Plenk, H; Walter, A; Salzer, M; Schreiber, V

    1994-01-01

    We report the clinical and tribological performance of 67 ceramic acetabular prostheses implanted between 1976 and 1979 without bone cement. They articulated with ceramic femoral heads mounted on mental femoral stems. After a mean elapsed period of 144 months, 59 sockets were radiographically stable but two showed early signs and six showed late signs of loosening. Four of the loose sockets have been revised. Histological analysis of the retrieved tissue showed a fibrous membrane around all the implants, with fibrocartilage in some. There was no bone ingrowth, and the fibrous membrane was up to 6 mm thick and infiltrated with lymphocytes, plasma cells, and macrophages. Intra- and extracellular birefringent wear particles were seen. Tribological analysis showed total wear rates in two retrieved alumina-on-alumina joints of 2.6 microns per year in a stable implant and 68 microns in a loose implant. Survival analysis showed a revision rate of 12.4% at 136 months.

  16. Preparation of alumina microspheres. Its application as in inorganic exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Santos, W.R. dos; Abrao, A [Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil). Centro de Engenharia Quimica

    1980-01-01

    Inorganic exchangers are widely used for adsorption and column partition chromatography. The main difficulty of using commercial alumina (in powder) for column chromatography is related to its packing, and the operations through the column become diffcult and time-consuming; also it turns to be virtually impossible to use large dimension columns. In order to eliminate these problems, a process for the preparation of alumina microspheres was developed as an adaptation of a similar process used to prepare nuclear fuel microspheres (UO/sub 2/, ThO/sub 2/). The flowsheet of this process is presented together with the analytical results of sphericity after calcination, granulometry, density and characterization by X-ray diffractometry. Solubility tests showed that the so-prepared microspheres are well resistant to strong acids and bases; retention tests showed their efficiency, mainly to copper.

  17. Evaluation of technological properties of alumina refractory systems-zirconia and zirconia-silica-alumina; Avaliacao das propriedades tecnologicas de refratarios dos sistemas alumina-zirconia e alumina-zirconia-silica

    Energy Technology Data Exchange (ETDEWEB)

    Marinho, A.R.O.; Carvalho, T.U.S.; Fagury Neto, E.; Rabelo, A.A., E-mail: adriano@unifesspa.edu.br [Universidade Federal do Sul e Sudeste do Para (UFSSPA), Maraba, PA (Brazil)

    2014-07-01

    Alumina-zirconia refractories are noted for being products of excellent cost-effective, however, zirconia may limit its use due to decreasing resistance to thermal shock. This study aims to evaluate these refractories with the addition of microsilica, which can greatly improve their properties. Were used the following starting materials: calcined alumina, zirconia (stabilized and monoclinic) in amounts of 2%, 4% and 6% by weight, plus microsilica (5%w.). The powders were milled together with binder and lubricant for conformation bodies by uniaxial pressing. The samples were dried, calcined and sintered at 1400 °C/2h were characterized using the methods of Archimedes, and scanning electron microscopy (SEM), chemical analysis using energy dispersive X-ray (EDS), and mechanical flexural strength tests at room temperature. Formulations with the presence of microsilica showed satisfactory results and optimized properties. (author)

  18. MICROWAVE JOINING OF ALUMINA CERAMIC AND HYDROXYLAPATITE BIOCERAMIC

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Microwave joining is a rapid developmental new techniqu e in recent years.This paper introduces a new microwave joining equipment which was made by our lab,succeeds in alumina ceramic-hydroxylapatite bioceramic j o in in the equipment, and analyzes the join situation of join boundary by using s canni ng electron microscope(SEM),this paper analyzes the mechanism of microwave joini ng also.

  19. Porous Alumina and Zirconia Ceramics With Tailored Thermal Conductivity

    Czech Academy of Sciences Publication Activity Database

    Gregorová, E.; Pabst, W.; Sofer, Z.; Jankovský, O.; Matějíček, Jiří

    2012-01-01

    Roč. 395, č. 1 (2012), 012022-012022 ISSN 1742-6588. [European Thermal Sciences Conference (Eurotherm)/6./. Poitiers, 04.09.2012-07.09.2012] Institutional support: RVO:61389021 Keywords : Ceramics * alumina * zirconia * porosity * thermal conductivity * pore-forming agent * oxide ceramics * starch * porosity Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://iopscience.iop.org/1742-6596/395/1/012022/pdf/1742-6596_395_1_012022.pdf

  20. On the thermally activated crack propagation in alumina

    International Nuclear Information System (INIS)

    Devezas, T.C.

    1983-01-01

    Subcritical crack growth was studied in the temperature 25-100 0 C in two commercial aluminas containing different amounts of a glassy phase. The experimental method employed was that of double torsion under constant load, using a device specially built to carry out mechanical tests at constant compressive load and high temperatures. Activation enthalpies of subcritical crack growth were determined for the two materials. (Author) [pt

  1. Ion irradiation effect of alumina and its luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Yasushi; Yamamoto, Shunya; Naramoto, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; My, N T

    1997-03-01

    The luminescence spectra of single crystalline alpha-alumina and ruby which has 0.02% of Cr{sub 2}O{sub 3} as a impurity, induced by 200 keV He{sup +} and Ar{sup +} irradiation were measured at room temperature as a function of irradiation dose. The analysis of the measured spectra showed the existence of three main luminescence features in the wavelength region of 250 to 350 nm, namely anionic color centers, F-center at 411 nm and F{sup +}-center at 330 nm and a band observed around 315 nm. As alpha-alumina was irradiated with He{sup +}, F-center and F{sup +}-center luminescence grew and decayed, but the behaviors of those were different from each other. It seems that a concentration quenching occurred on the F-center luminescence in the dose range above 1x10{sup 14} He/cm{sup 2}. Furthermore, F-center luminescence was strongly suppressed in ruby, compared with that in alumina. On the other hand, the luminescence band around 315 nm appeared only in the early stage of irradiation and did not show its growth part. The dose dependent behavior was similar to that of Cr{sup 3+} emission at 695 nm (R-line) in ruby in both cases of He{sup +} and Ar{sup +} irradiation. Based on the experimental results mentioned above, the processes of defect formation and excitation in alumina in the early stage of ion irradiation will be discussed. (author)

  2. Dependence of the Stabilization of -Alumina on the Spray Process

    Czech Academy of Sciences Publication Activity Database

    Stahr, C.Ch.; Saaro, S.; Berger, L.-M.; Herrmann, M.; Dubský, Jiří; Neufuss, Karel

    2007-01-01

    Roč. 16, 5-6 (2007), s. 822-830 ISSN 1059-9630 R&D Projects: GA ČR(CZ) GA106/05/0483 Institutional research plan: CEZ:AV0Z20430508 Keywords : -Al2O3 stabilization * alumina * chromia * solid solution * X-ray diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.204, year: 2007

  3. Antibacterial Activity of Zinc Oxide-Coated Nanoporous Alumina

    Science.gov (United States)

    2012-05-17

    made nanoporous alumina membranes, which were created by means of anodic oxidation of aluminum in an oxalic acid electrolyte, for treatment of skin...this study. All of the solutions were prepared using 18 M de-ionized water (lab supply) and trace metal grade nitric acid (Thermo Fisher Scientific...low production cost, repro- ducible reproduction, and facile reproduction approach for these materials. Using in vitro studies, keratinocytes (HaCaT

  4. Oxidation of mullite-zirconia-alumina-silicon carbide composites

    International Nuclear Information System (INIS)

    Baudin, C.; Moya, J.S.

    1990-01-01

    This paper reports the isothermal oxidation of mullite-alumina-zirconia-silicon carbide composites obtained by reaction sintering studied in the temperature interval 800 degrees to 1400 degrees C. The kinetics of the oxidation process was related to the viscosity of the surface glassy layer as well as to the crystallization of the surface film. The oxidation kinetics was halted to T ≤ 1300 degrees C, presumably because of crystallization

  5. Glass properties in the yttria-alumina-silica system

    Science.gov (United States)

    Hyatt, M. J.; Day, D. E.

    1987-01-01

    The glass formation region in the yttria-alumina-silica system was investigated. Properties of glasses containing 25 to 55 wt pct yttria were measured and the effect of the composition was determined. The density, refractive index, thermal-expansion coefficient, and microhardness increased with increasing yttria content. The dissolution rate in 1N HCl increased with increasing yttria content and temperature. These glasses were also found to have high electrical resistivity.

  6. Proton adsorption onto alumina: extension of multisite complexation (MUSIC) theory

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, K.; Blum, F.D.

    1999-09-01

    The adsorption isotherm of protons onto a commercial {gamma}-alumina sample was determined in aqueous nitric acid with sodium nitrate as a background electrolyte. Three discrete regions could be discerned in the log-log plots of the proton isotherm determined at the solution pH 5 to 2. The multisite complexation (MUSIC) model was modified to analyze the simultaneous adsorption of protons onto various kinds of surface species.

  7. Vitrification of high-level alumina nuclear waste

    International Nuclear Information System (INIS)

    Brotzman, J.R.

    1979-01-01

    Borophosphate glass compositions have been developed for the vitrification of a high-alumina calcined defense waste. The effect of substituting SiO 2 , P 2 O 5 and CuO for B 2 O 3 on the viscosity and leach resistance was measured. The effect of the alkali to borate ratio and the Li 2 O:Na 2 O ratio on the melt viscosity and leach resistance was also measured

  8. Organized Mesoporous Alumina: Synthesis, Structure and Potential in Catalysis

    Czech Academy of Sciences Publication Activity Database

    Čejka, Jiří

    2003-01-01

    Roč. 254, - (2003), s. 327-338 ISSN 0926-860X R&D Projects: GA AV ČR IAA4040001; GA ČR GA104/02/0571; GA MŠk ME 404 Institutional research plan: CEZ:AV0Z4040901 Keywords : organized mesoporous alumina * mesoporous molecular sieves * synthesis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.825, year: 2003

  9. Effect of yttrium on the oxide scale adherence of pre-oxidized silicon-containing heat-resistant alloy

    International Nuclear Information System (INIS)

    Yan Jingbo; Gao Yimin; Shen Yudi; Yang Fang; Yi Dawei; Ye Zhaozhong; Liang Long; Du Yingqian

    2011-01-01

    Highlights: → AE experiment shows yttrium has a beneficial effect on the pre-oxidized HP40 alloy. → Yttrium facilitates the formation of internal oxide after 10 h of oxidation. → Internal oxide changes the rupture behaviour of the oxide scale. → Twins form in the internal oxide and improve the binding strength of the scale. - Abstract: This paper investigates the effect of the rare earth element yttrium on the rupture behaviour of the oxide scale on the silicon-containing heat-resistant alloy during cooling. After 10 h of oxidation, yttrium is found to facilitate the formation of internal oxides (silica) at the scale-matrix interface. Due to the twinning observed by scanning transmission electron microscopy (STEM) in silica, the critical strain value for the scale failure can be dramatically improved, and the formation of cracks at the scale-matrix interface is inhibited.

  10. Near-field radiative heat transfer in mesoporous alumina

    International Nuclear Information System (INIS)

    Li Jing; Feng Yan-Hui; Zhang Xin-Xin; Huang Cong-Liang; Wang Ge

    2015-01-01

    The thermal conductivity of mesoporous material has aroused the great interest of scholars due to its wide applications such as insulation, catalyst, etc. Mesoporous alumina substrate consists of uniformly distributed, unconnected cylindrical pores. Near-field radiative heat transfer cannot be ignored, when the diameters of the pores are less than the characteristic wavelength of thermal radiation. In this paper, near-field radiation across a cylindrical pore is simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material are further analyzed. The research results show that the radiative heat transfer on a mesoscale is 2∼4 orders higher than on a macroscale. The heat flux and equivalent thermal conductivity of radiation across a cylindrical pore decrease exponentially with pore diameter increasing, while increase with temperature increasing. The calculated equivalent thermal conductivity of radiation is further developed to modify the thermal conductivity of the mesoporous alumina. The combined thermal conductivity of the mesoporous alumina is obtained by using porosity weighted dilute medium and compared with the measurement. The combined thermal conductivity of mesoporous silica decreases gradually with pore diameter increasing, while increases smoothly with temperature increasing, which is in good agreement with the experimental data. The larger the porosity, the more significant the near-field effect is, which cannot be ignored. (paper)

  11. Thermal and tensile properties of alumina filled PET nanocomposites

    Science.gov (United States)

    Nikam, Pravin N.; Deshpande, Vineeta D.

    2018-05-01

    In the present investigation, nanocomposites of poly(ethylene terephathalate)(PET) with different content (0 to 5 wt.%) of alumina nanoparticles (n-Al2O3) were prepared by melt-extrusion technique. Morphological characterization of samples was examined by transmission electron microscopy (TEM). Morphological analysis revealed that degree of dispersion of alumina nanoparticles (ANPs) was increased at lower content (i.e. upto 2 wt.%), which observed by TEM. Thermal and tensile measurements were carried out using and differential scanning calorimetry (DSC) and universal testing machine (UTM). The thermal analysis showed that the glass transition termperature (Tg), melting temperature (Tm), crystallization temperature (Tc) of PET/alumina nanocomposites (PNCs) were higher than neat PET (PET0). The heat enthalpy (ΔHm) of crystallization for PNCs was increased compared to PET0, which indicates that degree of crystallinity of PNCs also increased compared to PET0. The half-time (t0.5) of crystallization of PNCs were decreased compared to PET0 which indicates that the incorporation of ANPs nucleate the PET molecular chains and allowing the easily crystallization during nonisothermal process. The tensile analysis revealed that the tensile elastic modulus (i.e. Young's modulus) of PNCs increased almost linearly with increasing the content of ANPs while tensile elongation at break decreased nonlinearly. The tensile strength of PNCs increased with a 1 wt.% of ANPs whereas the higher content of ANPs decreased the tensile strength.

  12. Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

    Directory of Open Access Journals (Sweden)

    Morteza Aramesh

    2015-08-01

    Full Text Available A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general.

  13. Dielectric properties of alumina/zirconia composites at millimeter wavelengths

    International Nuclear Information System (INIS)

    Molla, J.; Heidinger, R.; Ibarra, A.; Link, G.

    1994-01-01

    Alumina-zirconia composites with ZrO 2 contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO 2 is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO 2 , t-ZrO 2 ). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al 2 O 3 , 14-21 for m-ZrO 2 and 40-45 for t-ZrO 2 . The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO 2 ; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO 2 , which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO 2 strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO 2 is avoided

  14. Environmental Sustainability of the Alumina Industry in Western Europe

    Directory of Open Access Journals (Sweden)

    Valentina Dentoni

    2014-12-01

    Full Text Available The implementation of European policies on environmental protection is enforcing some substantial modifications in the processing methods and technologies traditionally adopted in the alumina industry and, in particular, in the management of the alumina residue produced. The article analyses the evolution of the alumina production and the residue disposal practices in Western Europe. Some critical aspects regarding the legal implementation of the EU Directive on the landfill of waste are highlighted and discussed. With reference to the requirements established for the landfill of non-hazardous waste, a key point is represented by the possibility of reducing the deposit protection measures if the collection and treatment of leachate is not necessary. The flexibility introduced by the Directive is not incorporated into the Italian law; this fact may represent a major issue in the prospect of disposal conversion from wet to dry methods for companies operating in Italy, as it may endanger the economic sustainability of the plants’ upgrade, as well as the opportunity to attract outside investments.

  15. Synthesis of zeolite membrane (Y / α-alumina)

    International Nuclear Information System (INIS)

    Araujo, Ana Paula; Silva, Valmir Jose da; Crispin, Alana Carolyne; Rodrigues, Meiry Glaucia F.; Menezes, Romualdo R.

    2009-01-01

    The general aim of this study was to develop materials of the type: Y zeolite (hydrothermal synthesis), ceramic support (forming of powder) and zeolite membrane (rubbing). The preparation of the Y zeolite was conducted in accordance with the hydrothermal synthesis method, the time of crystallization was one day. The ceramic support was prepared by means of the forming of powder technique and subsequently subjected to sintering at a temperature of 1400 deg C/1h. The zeolite membrane (Y/α- alumina) was prepared by secondary growth method (rubbing). These materials were characterized by XRD and SEM. Obtaining Y zeolite could be confirmed by X ray diffractograms. From the images obtained by SEM, it was possible to derive from analysis that the Y zeolite is composed of a homogeneous morphology, where the particles are crowded, with uniform size. The results obtained for the ceramic support (α-alumina) showed that it displays characteristics peaks of aluminum oxide. By using micrographs it was possible to observe a heterogeneous microstructure with a compact form, without cracks upon the layers. According to the XRD, for the method of secondary growth (rubbing), it was observed that the Y zeolite which had been synthesized on the ceramic support displayed a crystalline structure. The micrography of the zeolite membrane (Y/α-alumina) showed the formation of a layer of zeolite on the ceramic support. (author)

  16. Investigation of vapor explosions with alumina droplets in sodium

    International Nuclear Information System (INIS)

    Zimmer, H.J.

    1991-02-01

    Within the analysis of severe hypothetical fast breeder accidents the consequence of a fuel-coolant interaction has to be considered i.e. the thermal interaction between hot molten fuel and sodium. Experiments have been performed to study the thermal fragmentation of a molten alumina droplet in sodium. Alumina temperatures up to 3100 K and sodium temperatures up to 1143 K were used. For the first time film boiling of alumina drops in sodium was achieved. With some droplets undergoing film boiling, the fragmentation was triggered by an externally applied pressure wave. The trigger was followed promptly by a strong reaction pressure wave if and only if a contact temperature threshold of T I =2060±160 K was exceeded. In agreement with similar experiments in which other materials were studied this threshold corresponds to an interfacial temperature close to the homogeneous nucleation temperature of the vaporising liquid. Based on the present and previous experimental results a model concept of thermal fragmentation is developed. (orig.) [de

  17. Removing Bacillus subtilis from fermentation broth using alumina nanoparticles.

    Science.gov (United States)

    Mu, Dashuai; Mu, Xin; Xu, Zhenxing; Du, Zongjun; Chen, Guanjun

    2015-12-01

    In this study, an efficient separation technology using Al2O3 nanoparticles (NPs) was developed for removing Bacillus subtilis from fermentation broth. The dosage of alumina nanoparticles used for separating B. subtilis increased during the culture process and remained stable in the stationary phase of the culture process. The pH of the culture-broth was also investigated for its effects on flocculation efficiency, and showed an acidic pH could enhance the flocculation efficiency. The attachment mechanisms of Al2O3 NPs to the B. subtilis surface were investigated, and the zeta potential analysis showed that Al2O3 NPs could attach to B. subtilis via electrostatic attachment. Finally, the metabolite content and the antibacterial effect of the fermentation supernatants were detected and did not significantly differ between alumina nanoparticle separation and centrifugation separation. Together, these results indicate a great potential for a highly efficient and economical method for removing B. subtilis from fermentation broth using alumina nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Synthesis and textural evolution of alumina particles with mesoporous structures

    Science.gov (United States)

    Liu, Xun; Peng, Tianyou; Yao, Jinchun; Lv, Hongjin; Huang, Cheng

    2010-06-01

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous γ-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl - in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into γ-Al 2O 3 particles with mesostructures after further calcination at 1173 K, whereas coexisting SO 42- can promote above morphology evolution and then transformed into γ-Al 2O 3 nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m 2 g -1 even after calcinations at 1173 K.

  19. On characterizing the mechanical properties of aluminum–alumina composites

    International Nuclear Information System (INIS)

    Gudlur, Pradeep; Boczek, Artur; Radovic, Miladin; Muliana, Anastasia

    2014-01-01

    The overall response of aluminum–alumina (Al–Al 2 O 3 ) composites depends strongly on their microstructural characteristics. We study the overall mechanical response of Al–Al 2 O 3 composites experimentally, using Resonant Ultrasound Spectroscopy (RUS) and uniaxial compressive testing. Microstructures of composite with 10% alumina volume content are constructed from the microstructural images of the composite obtained from scanning electron microscopy (SEM). The SEM images of the composite are converted to finite element (FE) meshes, which are used to solve the boundary value problem in order to determine the overall mechanical response of the Al–Al 2 O 3 composite. The responses generated from the micromechanical models are compared with the elastic modulus obtained from RUS and experimental stress–strain curves from uniaxial compression tests. Effects of processing, porosity, alumina content, thermal (residual) stress, and plastic deformation on the overall elastic modulus and response of the composites are also studied. We observed that slightly altering the processing method had a significant effect on the microstructural characteristics and in turn on the overall physical and mechanical properties of the composite. With changes in porosity by 2–3%, the elastic modulus was found to vary by 10–15 GPa approximately. We observed that the elastic moduli of the composites determined from the uniaxial compressive tests are close to those obtained from RUS

  20. Nanostructured thin films of indium oxide nanocrystals confined in alumina matrixes

    International Nuclear Information System (INIS)

    Bouifoulen, A.; Edely, M.; Errien, N.; Kassiba, A.; Outzourhit, A.; Makowska-Janusik, M.; Gautier, N.; Lajaunie, L.; Oueriagli, A.

    2011-01-01

    Nanocrystals of indium oxide (In 2 O 3 ) with sizes below 10 nm were prepared in alumina matrixes by using a co-pulverization method. The used substrates such as borosilicate glasses or (100) silicon as well as the substrate temperatures during the deposition process were modified and their effects characterized on the structural and physical properties of alumina-In 2 O 3 films. Complementary investigation methods including X-ray diffraction, optical transmittance in the range 250-1100 nm and transmission electron microscopy were used to analyze the nanostructured films. The crystalline order, morphology and optical responses were monitored as function of the deposition parameters and the post-synthesis annealing. The optimal conditions were found and allow realizing suitable nanostructured films with a major crystalline order of cubic phase for the In 2 O 3 nanocrystals. The optical properties of the films were analyzed and the key parameters such as direct and indirect band gaps were evaluated as function of the synthesis conditions and the crystalline quality of the films.

  1. Fine tuning of optical signals in nanoporous anodic alumina photonic crystals by apodized sinusoidal pulse anodisation.

    Science.gov (United States)

    Santos, Abel; Law, Cheryl Suwen; Chin Lei, Dominique Wong; Pereira, Taj; Losic, Dusan

    2016-11-03

    In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures. We systematically analyse the effect of the amplitude difference (from 0.105 to 0.840 mA cm -2 ), the pore widening time (from 0 to 6 min), the anodisation period (from 650 to 950 s) and the anodisation time (from 15 to 30 h) on the quality and the position of the characteristic photonic stop band and the interferometric colour of these photonic crystal structures using the aforementioned apodization functions. Our results reveal that a logarithmic negative apodisation function is the most optimal approach to obtain unprecedented well-resolved and narrow photonic stop bands across the UV-visible-NIR spectrum of NAA-based gradient-index photonic crystals. Our study establishes a fully comprehensive rationale towards the development of unique NAA-based photonic crystal structures with finely engineered optical properties for advanced photonic devices such as ultra-sensitive optical sensors, selective optical filters and all-optical platforms for quantum computing.

  2. A Study on the Effect of Nano Alumina Particles on Fracture Behavior of PMMA

    Directory of Open Access Journals (Sweden)

    Arezou Sezavar

    2015-04-01

    Full Text Available In the current research, the role of nano-sized alumina on deformation and fracture mechanism of Poly Methyl Methacrylate (PMMA was investigated. For this purpose, PMMA matrix nanocomposite reinforced with different wt% of alumina (i.e., 5, 10 and 15 were fabricated using the compression molding technique. Tensile properties of produced nanocomposites were studied using Zwick Z250 apparatus at cross head speed of about 5 mm/min. In order to specify the role of alumina nanoparticles on deformation and fracture mechanism of PMMA, microscopic evaluation was performed using scanning electron microscope (SEM. The achieved results prove that tensile properties of PMMA depend on alumina wt%. For example, addition of 15 wt% alumina to PMMA causes an increase of about 25% modulus of elasticity. Micrographs taken from the fracture surface of PMMA and its nanocomposites show deformation and fracture mechanism of PMMA changes as alumina is added to it.

  3. Deuterium permeation of amorphous alumina coating on 316L prepared by MOCVD

    Science.gov (United States)

    Li, Shuai; He, Di; Liu, Xiaopeng; Wang, Shumao; Jiang, Lijun

    2012-01-01

    The deuterium permeation behavior of the alumina coating on 316L stainless steel prepared by metal organic chemical vapor deposition (MOCVD) was investigated. The alumina coating was also characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM). It was found that the as-prepared coating consisted of amorphous alumina. This alumina coating had a dense, crack-free and homogeneous morphology. Although the alumina coating was amorphous, effective suppression of deuterium permeation was demonstrated. The deuterium permeability of the alumina coating was 51-60 times less than that of the 316L stainless steel and 153-335 times less than that of the referred low activation martensitic steels at 860-960 K.

  4. Role of Metal Oxides in Chemical Evolution: Interaction of Ribose Nucleotides with Alumina

    Science.gov (United States)

    Arora, Avnish Kumar; Kamaluddin

    2009-03-01

    Interaction of ribonucleotides—namely, 5‧-AMP, 5‧-GMP, 5‧-CMP, and 5‧-UMP—with acidic, neutral, and basic alumina has been studied. Purine nucleotides showed higher adsorption on alumina in comparison with pyrimidine nucleotides under acidic conditions. Adsorption data obtained followed Langmuir adsorption isotherm, and Xm and KL values were calculated. On the basis of infrared spectral studies of ribonucleotides, alumina, and ribonucleotide-alumina adducts, we propose that the nitrogen base and phosphate moiety of the ribonucleotides interact with the positive charge surface of alumina. Results of the present study may indicate the importance of alumina in concentrating organic molecules from dilute aqueous solutions in primeval seas in the course of chemical evolution on Earth.

  5. Experimental research on HEL and failure properties of alumina under impact loading

    Directory of Open Access Journals (Sweden)

    Xiao-wei Feng

    2016-06-01

    Full Text Available A series of plate impact experiments on alumina was conducted using a light gas gun in order to further investigate Hugoniot elastic limit (HEL and failure properties of alumina under shock compression. The velocity interferometer system for any reflector (VISAR was used to record the rear-free surface velocity histories of the alumina samples. According to the experimental results, the HELs of tested alumina samples with different thicknesses were measured, and the decay phenomenon of elastic wave in shocked alumina was studied. A phenomenological expression between HEL and thickness of sample was presented, and the causes of the decay phenomenon were discussed. The propagation of failure wave in shocked alumina was probed. The velocity and delayed time of failure wave propagation were obtained. The physical mechanism of the generation and propagation of failure was further discussed.

  6. An ICP AES method for determination of dysprosium and terbium in high purity yttrium oxide

    International Nuclear Information System (INIS)

    Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.

    2011-01-01

    High purity yttrium finds interesting application in astronavigation, luminescence, nuclear energy and metallurgical industries. Most of these applications require yttrium oxide of highest purity. Consequently there is a need for production of high purity yttrium oxide. Separation and purification of yttrium from other rare earths is a challenging task due to their close chemical properties. Liquid-liquid extraction and ion exchange have been widely used in the production of yttrium oxide of highest purity. Determination of impurities, especially other rare earths, in ppm level is required for process development and chemical characterization of the high purity Y 2 O 3 . Many methods have been described in literature. However since the advent of ICP AES much work in this area has been carried out by this technique. This paper describes the work done for determination of dysprosium (Dy) and terbium (Tb) in yttrium oxide using a high resolution sequential ICP AES. Emission spectra of rare earth elements are very complex and due to this complexity it is important to select spectral interference free analyte lines for determination of rare earths in rare earth matrix. For the determination of Dy and Tb in Y 2 O 3 , sensitive lines of Dy and Tb are selected from the instrument wavelength table and spectral interference free emission lines for the determination is selected by scanning around the selected wavelengths using 5 g/L Y solution and 5 mg/L standard solutions of Dy and Tb prepared in 4% nitric acid. It is found 353.170 nm line of Dy and 350.917 nm line Tb is suitable for quantitative determination. The signal to background ratio increases with increase in matrix concentration, i.e. from 1 to 5 mg/L. The optimum forward power is determined and it is found to be 1100W for Dy and 1000W for Tb. The instrument is calibrated using matrix matched standards containing 5g/L of Y matrix. Samples are dissolved in nitric acid and Y concentration is maintained at 5g/L. Two

  7. Radioembolization with Yttrium-90 microspheres for patients with unresectable hepatocellular carcinoma.

    Science.gov (United States)

    Bhangoo, Munveer Singh; Karnani, Diraj R; Hein, Paul N; Giap, Huan; Knowles, Harry; Issa, Chris; Steuterman, Steve; Pockros, Paul; Frenette, Catherine

    2015-10-01

    Hepatocellular carcinoma (HCC) is aggressive primary malignancy of the liver that most commonly presents late in the disease course. As a result, the majority of patients are not candidates for curative therapies. Locoregional therapies including Yttrium-90 (Y-90) radioembolization play an important role in management of the vast majority of patients with HCC. Patients with unnresectable HCC (n=17) treated with Y-90 radioembolization from 2005 to 2014 were evaluated retrospectively. Data was abstracted from medical records including patient charts, laboratory data, and imaging. Toxicities were recorded using Common Terminology Criteria 3.0. Response was recorded according to modified RECIST (mRECIST) criteria. Seventeen patients received 33 treatments with Y-90 radioembolization. A majority (65%) received TheraSphere with a minority (35%) receiving SIR-Spheres. The median treatment activity delivered was 1.725 gBq (range, 1.4-2.5 gBq). The median treatment dose delivered was 100 Gy (range, 90-120 Gy). The median lung shunt fraction was 2.02% (range, 1.5-4.1%). The most common clinical toxicity among all patients was nausea and vomiting (59%), primarily grade 1 and 2. Other post-treatment findings included abdominal pain (29%), fatigue (53%), and weight loss (18%). One patient developed a grade 5 gastric ulcer after the treatment. A clinical benefit, defined as patients achieving complete response (CR), partial response (PR) or stable disease (SD), was seen in 48% of patients. PR was seen in 24% of cases; progressive disease (PD) was noted in 35%. Patients survived for a median of 8.4 months (range, 1.3 to 21.1 months) after the first radioembolization treatment. Median survival after Y-90 treatment was 8.4 months among patients treated TheraSphere as compared with 7.8 months in patients treated with SIR-Spheres. The mean overall survival from the time of diagnosis was 11.7 months (range, 3.4 to 43.2 months). For patients with unresectable HCC, Y-90

  8. Lanthanum and yttrium oxysulfides activated by europium: (Ln1-x Eux)2 O2 S - Synthesis and characterization

    International Nuclear Information System (INIS)

    Luiz, J.M.

    1989-01-01

    The synthesis of lanthanum and yttrium oxysulfides activated by europium were obtained by thermal decomposition of lanthanum and yttrium oxalates doped with europium, under an argon and sulphur atmosphere. The thermal decomposition of these compounds is studied by differential thermal analysis (DTA). The characterization of these oxysulfides were made by chemical analyses, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and emission spectroscopy. (M.V.M.)

  9. Comparative study on sintered alumina for ballistic shielding application; Estudo comparativo entre aluminas sinterizadas visando aplicacao em blindagem balistica

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Francisco Cristovao Lourenco de; Goncalves, Diniz Pereira [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. de Aeronautica e Espaco

    1997-12-31

    This work presents a development of the armor made from special ceramic materials and kevlar. An experimental investigation was conducted to study the ballistic penetration resistance on three samples taken from sintered alumina: a commercial one and two formulations A and B made in IAE/CTA. The main differences between the two formulations was the grain size and bend resistance. The knowledge of the mechanisms during the penetration and perforation process allowed to apply a ductile composite laminate made form kevlar under the alumina to delay its rupture. The last ballistic test showed how a Weibull`s modulii and other mechanical properties are able to improve ballistic penetration resistance. (author) 3 refs.

  10. Heterogeneous burnable poisons. Sinterability study in oxidizing atmosphere of alumina-gadolinia and alumina-boron carbide compounds

    International Nuclear Information System (INIS)

    Agueda, H.C.; Leiva, S.F.; Russo, D.O.

    1990-01-01

    Solid burnable poisons are used in reactors cooled by pressure light water (PLWR) with the purpose of controlling initial reactivity in the first reactor's core. The burnable poisons may be uniformly mixed with the fuel -known as 'homogeneous' poisons-; or constituting separate elements -known as heterogeneous poisons-. The purpose of this work is to present the results of two sinterability studies, performed on Al 2 O 3 -Gd 2 O 3 and Al 2 O 3 -B 4 C, where alumina acts as inert matrix, storing the absorbing elements as Gd 2 O 3 or B 4 C. The elements were sintered at an air atmosphere and additives permitting the obtention of a greater density alumina were tested at lower temperatures than the characteristic for this material, in order to determine its compatibility with the materials dealt with herein. (Author) [es

  11. Decomposition of silica-alumina ores of Afghanistan by sulfuric acid

    International Nuclear Information System (INIS)

    Khomidi, A.K.; Mamatov, E.D.

    2016-01-01

    Present article is devoted to decomposition of silica-alumina ores of Afghanistan by sulfuric acid. Physicochemical properties of initial silica-alumina ores were studied by means of X-ray phase, differential thermal and silicate analysis. The influence of temperature, process duration and acid concentration on extraction rate of valuable components was considered. The optimal conditions of decomposition of silica-alumina ores of Afghanistan by sulfuric acid were proposed.

  12. Fabrication of a novel aluminum surface covered by numerous high-aspect-ratio anodic alumina nanofibers

    OpenAIRE

    Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2015-01-01

    The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The de...

  13. Removal of Arsenic from Drinking Water Using Modified Activated Alumina

    Directory of Open Access Journals (Sweden)

    Mohammad Mosaferi

    2005-09-01

    Full Text Available Considering contamination of drinking water to arsenic in some villages ofIran. In order to develop a simple method for household water treatment in rural areas, efficiency of  modified activated alumina with iron compounds- a product of Alcan Company with trade name of AAFS-50- was studied Equilibrium batch experiments were carried out using shaker incubator and arsenic was analyzed with SDDC method. Effects of initial concentration of arsenic, adsorbent dose, oxidation state of arsenic, pH and oxidation with chlorine on adsorption were studied. Correlation coefficient of Freundlich and Laungmuier  isotherms  for As(V and As(III were 0.964 , 0.991 and 0.970, 0.978 respectively . These results show that adsorption of arsenic on modified activated alumina is compatible with both models specially Laungmuier models. Removal efficiency of As(V at 0.5 ,1 and 2 hr increased with doubling the adsorbent dose from 44.8 to 72%, 69.6 to 90.8 and 92.4 to 98% ; respectively. Experiments using different concentrations of arsenic showed that adsorption of arsenic on activated alumina are a first order reaction that is, rate of reaction is dependent on intial; concentration of arsenic. Removal efficiency for concentration of 0.250 mg/L of arsenic, with increasing of reaction time from 15 min to 60 min, increased 1.54 times and reached from 61% to 94%. During 2hrs, removal of As(V and As(III were 96% and 16% respectively. Using 1.5 mg/L Chlorine as oxidant agent, removal of As(III was increased to 94%. In the case of pH effect, rate of adsorption increased for arsenite, with increasing of pH to 8 and decreased with more increasing, so that adsorption at pH 14 was equal to pH 2. For arsenate, the most adsorption was observed at pH between 6 to 8 . These results show that by using the studied activated alumina, there will not be need for adjustment of pH and the activated alumina used in this study could have application as a safe adsorbent for removal of

  14. Laser-induced reaction alumina coating on ceramic composite

    Science.gov (United States)

    Xiao, Chenghe

    Silicon carbide ceramics are susceptible to corrosion by certain industrial furnace environments. It is also true for a new class of silicon carbide-particulate reinforced alumina-matrix composite (SiCsb(P)Alsb2Osb3) since it contains more than 55% of SiC particulate within the composite. This behavior would limit the use of SiCsb(P)Alsb2Osb3 composites in ceramic heat exchangers. Because oxide ceramics corrode substantially less in the same environments, a laser-induced reaction alumina coating technique has been developed for improving corrosion resistance of the SiCsb(P)Alsb2Osb3 composite. Specimens with and without the laser-induced reaction alumina coating were subjected to corrosion testing at 1200sp°C in an air atmosphere containing Nasb2COsb3 for 50 ˜ 200 hours. Corroded specimens were characterized via x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The uncoated SiCsbP/Alsb2Osb3 composite samples experienced an initial increase in weight during the exposure to Nasb2COsb3 at 1200sp°C due to the oxidation of residual aluminum metal in the composite. There was no significant weight change difference experienced during exposure times between 50 and 200 hours. The oxidation layer formed on the as-received composite surface consisted of Si and Alsb2Osb3 (after washing with a HF solution). The oxidation layer grew outward and inward from the original surface of the composite. The growth rate in the outward direction was faster than in the inward direction. The formation of the Si/Alsb2Osb3 oxidation layer on the as-received composite was nonuniform, and localized corrosion was observed. The coated samples experienced very little mass increase. The laser-induced reaction alumina coating effectively provided protection for the SiCsbP/Alsb2Osb3 composite by keeping the corrodents from contacting the composite and by the formation of some refractory compounds such as Nasb2OAlsb2Osb3SiOsb2 and Nasb2Alsb{22}Osb

  15. Highly efficient and large-scale fabrication of superhydrophobic alumina surface with strong stability based on self-congregated alumina nanowires.

    Science.gov (United States)

    Peng, Shan; Tian, Dong; Yang, Xiaojun; Deng, Wenli

    2014-04-09

    In this study, a large-area superhydrophobic alumina surface with a series of superior properties was fabricated via an economical, simple, and highly effective one-step anodization process, and subsequently modified with low-surface-energy film. The effects of the anodization parameters including electrochemical anodization time, current density, and electrolyte temperature on surface morphology and surface wettability were investigated in detail. The hierarchical alumina pyramids-on-pores (HAPOP) rough structure which was produced quickly through the one-step anodization process together with a low-surface-energy film deposition [1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES) and stearic acid (STA)] confer excellent superhydrophobicity and an extremely low sliding angle. Both the PDES-modified superhydrophobic (PDES-MS) and the STA-modified superhydrophobic (STA-MS) surfaces present fascinating nonwetting and extremely slippery behaviors. The chemical stability and mechanical durability of the PDES-MS and STA-MS surfaces were evaluated and discussed. Compared with the STA-MS surface, the as-prepared PDES-MS surface possesses an amazing chemical stability which not only can repel cool liquids (water, HCl/NaOH solutions, around 25 °C), but also can show excellent resistance to a series of hot liquids (water, HCl/NaOH solutions, 30-100 °C) and hot beverages (coffee, milk, tea, 80 °C). Moreover, the PDES-MS surface also presents excellent stability toward immersion in various organic solvents, high temperature, and long time period. In particular, the PDES-MS surface achieves good mechanical durability which can withstand ultrasonication treatment, finger-touch, multiple fold, peeling by adhesive tape, and even abrasion test treatments without losing superhydrophobicity. The corrosion resistance and durability of the diverse-modified superhydrophobic surfaces were also examined. These fascinating performances makes the present method suitable for large

  16. Absorption of Ethylene on Membranes Containing Potassium Permanganate Loaded into Alumina-Nanoparticle-Incorporated Alumina/Carbon Nanofibers.

    Science.gov (United States)

    Tirgar, Ashkan; Han, Daewoo; Steckl, Andrew J

    2018-06-06

    Ethylene is a natural aging hormone in plants, and controlling its concentration has long been a subject of research aimed at reducing wastage during packaging, transport, and storage. We report on packaging membranes, produced by electrospinning, that act as efficient carriers for potassium permanganate (PPM), a widely used ethylene oxidant. PPM salt loaded on membranes composed of alumina nanofibers incorporating alumina nanoparticles outperform other absorber systems and oxidize up to 73% of ethylene within 25 min. Membrane absorption of ethylene generated by avocados was totally quenched in 21 h, and a nearly zero ethylene concentration was observed for more than 5 days. By comparison, the control experiments exhibited a concentration of 53% of the initial value after 21 h and 31% on day 5. A high surface area of the alumina nanofiber membranes provides high capacity for ethylene absorption over a long period of time. In combination with other properties, such as planar form, flexibility, ease of handling, and lightweight, these membranes are a highly desirable component of packaging materials engineered to enhance product lifetime.

  17. Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, Katherine [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The viscosities of both aqueous and cyanate ester monomer (BECy) based suspensions of alumina nanoparticle were studied. The applications for these suspensions are different: aqueous suspensions of alumina nanoparticles are used in the production of technical ceramics made by slip casting or tape casting, and the BECy based suspensions are being developed for use in an injection-type composite repair resin. In the case of aqueous suspensions, it is advantageous to achieve a high solids content with low viscosity in order to produce a high quality product. The addition of a dispersant is useful so that higher solids content suspensions can be used with lower viscosities. For BECy suspensions, the addition of nanoparticles to the BECy resin is expected to enhance the mechanical properties of the cured composite. The addition of saccharides to aqueous suspensions leads to viscosity reduction. Through DSC measurements it was found that the saccharide molecules formed a solution with water and this resulted in lowering the melting temperature of the free water according to classic freezing point depression. Saccharides also lowered the melting temperature of the bound water, but this followed a different rule. The shear thinning and melting behaviors of the suspensions were used to develop a model based on fractal-type agglomeration. It is believed that the structure of the particle flocs in these suspensions changes with the addition of saccharides which leads to the resultant viscosity decrease. The viscosity of the BECy suspensions increased with solids content, and the viscosity increase was greater than predicted by the classical Einstein equation for dilute suspensions. Instead, the Mooney equation fits the viscosity behavior well from 0-20 vol% solids. The viscosity reduction achieved at high particle loadings by the addition of benzoic acid was also investigated by NMR. It appears that the benzoic acid interacts with the surface of the alumina particle which may

  18. Reduction in Friction and Wear of Alumina Surfaces as Assisted with Surface-Adsorbing Polymers in Aqueous Solutions

    DEFF Research Database (Denmark)

    Røn, Troels; Lee, Seunghwan

    2016-01-01

    We have investigated the aqueous lubricating effects of various polymers for the sliding contacts of self-mated alumina surfaces in neutral aqueous environment. Given that isoelectric point (IEP) of alumina is ca. pH 9, polyanions can readily adsorb onto alumina surface at neutral pH via electros......We have investigated the aqueous lubricating effects of various polymers for the sliding contacts of self-mated alumina surfaces in neutral aqueous environment. Given that isoelectric point (IEP) of alumina is ca. pH 9, polyanions can readily adsorb onto alumina surface at neutral pH via...

  19. The effect of alumina nanofillers size and shape on mechanical behavior of PMMA matrix composite

    Directory of Open Access Journals (Sweden)

    Ben Hasan Somaya Ahmed

    2014-01-01

    Full Text Available Composites with the addition of alumina nanofillers show improvement in mechanical properties. The PMMA polymer was used as a matrix and two different types of nanofillers, having extremely different shapes were added in the matrix to form the composite. Reinforcements were based on alumina nanoparticles having either spherical shape or whiskers having the length to diameter ratio of 100. The influence of alumina fillers size, shape and fillers loading on mechanical properties of prepared composite were studied using the nanoindentation measurements and dynamic mechanical analysis. It was observed that both alumina whiskers and alumina spherical nanoparticles added in the PMMA matrix improved the mechanical properties of the composite but the improvement was significantly higher with alumina whisker reinforcement. The concentration of the reinforcing alumina spherical nanoparticles and alumina whiskers in PMMA matrix varied up to 5 wt. %. The best performance was obtained by the addition of 3 wt. % of alumina whiskers in the PMMA matrix with regard to mechanical properties of the obtained composite.

  20. Determination of calcium and magnesium in nuclear grade alumina by ion chromatography technique

    International Nuclear Information System (INIS)

    Hespanhol, E.C.B.; Pires, M.A.F.; Atalla, L.T.

    1987-07-01

    A simple method for solubilization of alumina and separation of magnesium and calcium from alumina matrix was developed by initial coprecipitation of those elements with iron(III) hydroxide. Calcium and magnesium were later separated from iron chloride anionic complex in a Dowex 1-X 10 anionic exchange resin. The ion chromatography tecnnique was employed for the analysis of calcium and magnesium. One hundred percent recovery for calcium and magnesium was obtained in their separation from alumina. A precision of 6% and 10% for magnesium and calcium, respectively, was obtained in alumina samples analysis which contain less than 0,02% of magnesium and less than 0,08% of calcium. (Author) [pt

  1. Fabrication of a novel aluminum surface covered by numerous high-aspect-ratio anodic alumina nanofibers

    Science.gov (United States)

    Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2015-11-01

    The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The density of the anodic alumina nanofibers decreased as the applied voltage increased in the 10-75 V range. However, active electrochemical dissolution of the aluminum substrate occurred at a higher voltage of 90 V. Low temperature anodizing at 273 K resulted in the formation of long alumina nanofibers measuring several micrometers in length, even though a long processing time was required due to the low current density during the low temperature anodizing. In contrast, high temperature anodizing easily resulted in the formation and chemical dissolution of alumina nanofibers. The structural nanofeatures of the anodic alumina nanofibers were controlled by choosing of the appropriate electrochemical conditions, and numerous high-aspect-ratio alumina nanofibers (>100) can be successfully fabricated. The anodic alumina nanofibers consisted of a pure amorphous aluminum oxide without anions from the employed electrolyte.

  2. Surface area, crystal morphology and characterization of transition alumina powders from a new gibbsite precursor

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Vieira Coelho

    2007-06-01

    Full Text Available A new procedure was used to prepare a microcrystalline powder constituted by thin euhedral hexagonal gibbsite plates, 0.2 to 0.6 µm in diameter and 32 nm thick. The powder, fired between 200 and 1000 °C, produced chi and kappa transition aluminas. Alpha-alumina is formed from 1000 °C and recrystallized up to 1500 °C. At 1000 °C, kappa- and alpha-alumina coexisted, but kappa-alumina could only be characterized by SAED. The details of the internal organization of the transition alumina pseudomorphs were clearly observable in TEM due to the great thinness of the I-gibbsite plates. The specific surface area varied from pristine I-gibbsite (24.9 m².g-1 to chi- and kappa transition aluminas (25.4 m².g-1 at 1000 °C to alpha-alumina (4.0 m².g-1 at 1500 °C. The maximum value of specific surface area is 347 m².g-1 in chi-alumina powder at 300 °C, a difference from Bayer gibbsite, in which the chi-alumina highest surface area is 370 m².g-1 at 400 °C.

  3. On the possibility of producing alumina ceramic with a slight electrical conductivity

    CERN Document Server

    Caspers, Fritz

    1989-01-01

    Antistatic alumina ceramic is desirable for certain particle accelerator applications. In general, highly insulating surface close to a charged particle beam must be avoided in order to prevent the formation of ion pockets and other unwanted electrical effects. For the AA vacuum chamber (UHV), an antistatic ferrite has been produced and successfully installed. The fabrication of antistatic alumina might be possible in a similar way. By using certain metal oxides in the cement, which holds the alumina particles together, a slight conductivity could be obtained after the firing and sintering process, without deteriorating the mechanical and outgassing properties of the alumina compound.

  4. Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

    International Nuclear Information System (INIS)

    Yusof Abdullah; Abd Fatah Awang Mat; Mohd Ali Sufi; Sarimah Mahat; Razali Kassim; Nurhaslinda Abdullah.

    1996-03-01

    The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

  5. Some peculiarities of thermoemission of the cathodes on the base of tanthanum and yttrium oxides

    International Nuclear Information System (INIS)

    Podgornyj, V.I.

    1982-01-01

    Thermoemission cathode characteristics on the basis of (La 2 O 3 ) lanthanum, and yttrium oxides which are used already in prctice but emission mechanism of which remains yet insufficiently elucidated, were investigated. It is shown that the heating of cathodes on the basis of Y 2 O 3 and La 2 O 3 at activation temperatures during 2-3 h with successive cooling results in the state of surface with increased thermoemission activity. It is established that the cathode heating in electric field of positive polarity results in decreasing thermoemission activity of lanthanum oxide by approximately 0.35 eV and for yttrium oxide - by approximately 0.05 eV as compared with the heating in the field of negative polarity. The effect obtained is related to the change in the metal adatom concentration on the cathode surface

  6. An XRF method for determination of common rare earth impurities in high purity yttrium oxide

    International Nuclear Information System (INIS)

    Dixit, R.M.; Deshpande, S.S.

    1975-01-01

    An XRF method for the estimation of Eu, Gd, Tb, Dy, Ho, Er and Yb in yttrium oxide has been developed. Samples are converted to yttrium oxalate and presented to the spectrometer in the form of pressed pellets. Philips PW-1220, a semi-automatic x-ray spectrometer, is used for the analysis. Line interference problems are studied for selecting analysis lines. For the elements except that of Yb, the lower estimation limit is 0.005% and for Yb, it is 0.01%. The average standard deviation is approximately 5% for various elements in the concentration range of 0.005% to 1.0%. The method has been tested for its accuracy by analysing synthesized samples with known composition at three different concentrations. (author)

  7. Characterization of photoluminescent europium doped yttrium oxide thin-films prepared by metallorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    McKittrick, J.; Bacalski, C.F.; Hirata, G.A.; Hubbard, K.M.; Pattillo, S.G.; Salazar, K.V.; Trkula, M.

    1998-01-01

    Europium doped yttrium oxide, (Y 1-x Eu x ) 2 O 3 , thin-films were deposited on silicon and sapphire substrates by metallorganic chemical vapor deposition (MOCVD). The films were grown in a MOCVD chamber reacting yttrium and europium tris(2,2,6,6-tetramethyl-3,5,-heptanedionates) precursors in an oxygen atmosphere at low pressures (5 Torr) and low substrate temperatures (500--700 C). The films deposited at 500 C were flat and composed of nanocrystalline regions of cubic Y 2 O 3 , grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600 C developed from the flat, nanocrystalline morphology into a plate-like growth morphology oriented in the [111] with increasing deposition time. Monoclinic Y 2 O 3 :Eu 3+ was observed in x-ray diffraction for deposition temperatures ≥600 C on both (111) Si and (001) sapphire substrates. This was also confirmed by the photoluminescent emission spectra

  8. Separation of yttrium using carbon nanotube doped polymeric beads impregnated with D2EHPA

    International Nuclear Information System (INIS)

    Dasgupta, Kinshuk; Yadav, Kartikey K.; Singh, D.K.; Anitha, M.; Singh, H.

    2013-01-01

    Di-2-ethylhexyl phosphoric acid impregnated polyethersulfone based composite beads in combination with additives such as polyvinyl alcohol (PVA) and multiwalled carbon nanotube (MWCNT) has been prepared by non-solvent phase inversion method. The synthesized beads were characterized by scanning electron microscopy, thermogravimetry and infra-red spectroscopy. Effect of additives on bead morphology, solvent impregnation capacity, extractability and stability has been examined to compare their suitability for yttrium recovery from acidic medium. Microstructural investigation as well as experimental findings confirmed the role of additives in modifying the pore structures in beads, responsible for varied degree of yttrium extraction. Further the role of metal ion concentration in aqueous phase on its recovery by polymeric beads was also evaluated. Among the tested beads PES/D2EHPA/MWCNT/PVA beads were found to be superior for Y(Ill) extraction. (author)

  9. Preparation of yttrium iron garnet (YIG) by modified domestic iron oxide

    International Nuclear Information System (INIS)

    Mozaffari, M.; Amighian

    2002-01-01

    Iron oxide by product of a local steel complex was modified to use for preparation of Yttrium iron garnet (YIG). The improvement was necessary to reduce impurities, especially the Si0 2 and Cl contents, which have deteriorative effects on magnetic properties and equipment used for preparation of the samples. The modified iron oxide was then mixed with Yttrium oxide of Merck Company in appropriate proportion to obtain a stoichiometric single phase YIG, using the conventional ceramic technique. XRD and SEM equipments were used to identify the resulting phases and microstructure respectively. Magnetic parameters were measured by VSM. Curie temperature of the samples was obtained by DTG (M) method. The results were compared with those obtained from samples that made by Merck iron oxide. There are small differences between the results. This was discussed according to extra pores and minute secondary phase in the samples made by domestic iron oxide. (Author)

  10. Determination of yttrium using YO band head obtained by laser enhanced ionization spectrometry

    International Nuclear Information System (INIS)

    Deshpande, S.S.; Khanna, P.P.

    1997-04-01

    The determination of yttrium (Y) in water in the concentration range of 2 μg/ml to 200 μg/ml by laser enhanced ionisation (LEI) technique is reported. The YO band head at 584.27 nm belonging to A 2 Π - X 2 Σ + system is used for LEI signal detection. It is also shown that the LEI signal is enhanced when the mixture of air - acetylene - argon (AAA) is used instead of commonly used air-acetylene (AA) mixture. In the present work an XeCl laser (308 nm) pumped rhodamine 6G dye laser, covering a range of 570-610 nm is used. The sample/standard in solution form is aspirated into the flame with pneumatic nebulizer. The working curve is a straight line showing linear dependence of LEI signal with yttrium concentration. The relative standard deviation calculated at 100 μg/ml is found to be 2.4 %. (author)

  11. Quantum design and synthesis of a boron-oxygen-yttrium phase

    International Nuclear Information System (INIS)

    Music, Denis; Chirita, Valeriu; Kreissig, Ulrich; Czigany, Zsolt; Schneider, Jochen M.; Helmersson, Ulf

    2003-01-01

    Ab initio calculations are used to design a crystalline boron-oxygen-yttrium (BOY) phase. The essential constituent is yttrium substituting for oxygen in the boron suboxide structure (BO 0.17 ) with Y/B and O/B ratios of 0.07. The calculations predict that the BOY phase is 0.36 eV/atom more stable than crystalline BO 0.17 and experiments confirm the formation of crystalline thin films. The BOY phase was synthesized with reactive rf magnetron sputtering and identified with x-ray and selected area electron diffraction. Films with Y/B ratios ranging from 0.10 to 0.32, as determined via elastic recoil detection analysis, were grown over a wide range of temperatures (300-600 deg. C) and found to withstand 1000 deg. C

  12. Yttrium-90 used to treat colon cancer: Awaiting investigational new drug approval

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    A new radiation treatment takes just 14 to 21 days to shrink colorectal tumors in laboratory mice, is under review for clinical trials with human cancer patients. The treatment has succeeded in reducing the size of tumors by up to 95%. Colon cancer, the second leading cause of cancer deaths in the US, is extremely difficult to treat unless it is detected early enough for surgical procedures. In laboratory tests over the last 5 years, a team of researchers has developed the treatment using yttrium-90. The yttrium-90 is transported to the tumors by attaching it to monoclonal antibodies that seek out the cancer cells. Once the radioisotope has been targeted to the tumor, the radiation destroys many of the cells, dramatically reducing the size of the tumor. Since this treatment usually does not completely eliminate all the cancer cells, it cannot be called a cure, but it does seem to be an effective method of shrinking colorectal tumors

  13. Mass synthesis of yttrium oxide nano-powders using radio frequency (RF) plasma

    International Nuclear Information System (INIS)

    Ghorui, S.; Sahasrabudhe, S.N.; Chakravarthy, Y.; Nagaraj, A.; Das, A.K.; Dhamale, G.

    2014-01-01

    Mass synthesis of nano-phase Yttrium Oxide (Y 2 O 3 ) from commercially available coarse grain powder is reported. Nano-sized high purity Y 2 O 3 is an important and critical constituent of ceramics like YAG (Yttrium aluminum garnet: Y 3 Al 5 O 12 ) for laser applications. The system is characterized in terms of its thermal and electrical behavior. Boltzmann plot technique is used to measure axial variation of temperature of the generated plasma. The synthesized particles are characterized in terms of XRD, SEM, TEM and BET analyses for qualification of the developed system. Major features observed are efficient conversion into nanometer-sized highly spherical particles, narrow size distribution, highly crystallite nature and highly pure phases. The particle distribution (from TEM) peaks within 20-30 nm. Average particle sizes determined from different methods like XRD, TEM and BET are very close to each other and point toward particle sizes within 20 to 30 nm

  14. Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

    International Nuclear Information System (INIS)

    Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J.; Kowalczyk, Z.; Grasza, K.

    1994-01-01

    High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab

  15. Preparation of polycrystalline lithium-yttrium fluoride for subsequent mono crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, E.; Radomski, J.; Diduszko, R.; Iwanejko, J. [Institute of Vacuum Technology, Warsaw (Poland); Kowalczyk, Z. [Warsaw Univ. (Poland); Grasza, K. [Polska Akademia Nauk, Warsaw (Poland). Inst. Fizyki

    1994-12-31

    High purity lithium-yttrium (YLF) doped with rare earth elements (Nd, Pr, Ho or Tm) was obtained in a two-stage synthesis consisting of (1) reaction of ammonium fluoride with a mixture of lithium carbonate, yttrium oxide, and oxides of lanthanides, and (2) heating of the obtained reaction products at a temperature of about 700 C in an inert gas atmosphere. The phase and chemical purities of the obtained materials were characterized by X-ray diffraction and mass spectrometry techniques. Single crystal growth tests were carried out by means of the Bridgman method. The results showed that the proposed method for manufacture of polycrystalline YLF doped with rare earth elements is appropriate in principle but some parameters of the preparation process are to be more strictly defined. (author). 9 refs, 4 figs, 1 tab.

  16. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate; Aproveitamento de itrio e lantanio de um carbonato de terras raras de baixo teor em cerio, de um carbonato de itrio e de um oxido de terras itricas

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Mari Estela de

    2006-07-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  17. Hydrothermal synthesis, crystal structures and photoluminescence properties of mixed europium–yttrium organic frameworks

    International Nuclear Information System (INIS)

    Han Yinfeng; Fu Lianshe; Mafra, Luís; Shi, Fa-Nian

    2012-01-01

    Three mixed europium–yttrium organic frameworks: Eu 2−x Y x (Mel)(H 2 O) 6 (Mel=mellitic acid or benzene-1,2,3,4,5,6-hexacarboxylic acid, x=0.38 1, 0.74 2, and 0.86 3) have been synthesized and characterized. All the compounds contain a 3-D net with (4, 8)-flu topology. The study indicates that the photoluminescence properties are effectively affected by the different ratios of europium and yttrium ions, the quantum efficiency is increased and the Eu 3+ lifetime becomes longer in these MOFs than those of the Eu analog. - Graphical abstract: Three mixed europium and yttrium organic frameworks: Eu 2−x Y x (Mel)(H 2 O) 6 (Mel=mellitic acid) have been synthesized and characterized. All the compounds contain a 3-D net with (4, 8)-flu topology. The study indicates that the photoluminescence properties are effectively affected by the different ratios of europium and yttrium ions, the quantum efficiency is increased and the Eu 3+ lifetime becomes longer in these MOFs than those of the Eu analog. Highlights: ► Three (4, 8)-flu topological mixed Eu and Y MOFs were synthesized under mild conditions. ► Metal ratios were refined by the single crystal data consistent with the EDS analysis. ► Mixed Eu and Y MOFs show longer lifetime and higher quantum efficiency than the Eu analog. ► Adding inert lanthanide into luminescent MOFs enlarges the field of luminescent MOFs.

  18. Peripheral Blood Lymphocyte Depletion After Hepatic Arterial {sup 90}Yttrium Microsphere Therapy for Hepatocellular Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Carr, Brian I., E-mail: brianicarr@hotmail.com [Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA and Department of Nutrition and Exptl Biology, Saverio De Bellis Medical Research Institute, Castellana Grotte, Bari (Italy); Metes, Diana M. [Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA and Department of Nutrition and Exptl Biology, Saverio De Bellis Medical Research Institute, Castellana Grotte, Bari (Italy)

    2012-03-01

    Purpose: The short- and long-term effects of {sup 90}Yttrium microspheres therapy for hepatocellular carcinoma (HCC) on peripheral blood lymphocytes are unknown and were therefore examined. Methods and Materials: Ninety-two HCC patients were enrolled in a {sup 90}Yttrium therapy study and routine blood counts were examined as part of standard clinical monitoring. Results: We found an early, profound, and prolonged lymphopenia. In a subsequent cohort of 25 additional HCC patients, prospective flow cytometric immune-monitoring analysis was performed to identify specific changes on distinct lymphocyte subsets (i.e., CD3, CD4, CD8 T, and CD19 B lymphocytes) and NK cells absolute numbers, in addition to the granulocytes and platelets subsets. We found that the pretreatment lymphocyte subset absolute numbers (with the exception of NK cells) had a tendency to be lower compared with healthy control values, but no significant differences were detected between groups. Posttherapy follow-up revealed that overall, all lymphocyte subsets, except for NK cells, were significantly (>50% from pretherapy values), promptly (as early as 24 h) and persistently (up to 30 months) depleted post-{sup 90}Yttrium microspheres therapy. In contrast, granulocytes increased rapidly (24 h) to compensate for lymphocyte depletion, and remained increased at 1-year after therapy. We further stratified patients into two groups, according to survival at 1 year. We found that lack of recovery of CD19, CD3, CD8, and especially CD4 T cells was linked to poor patient survival. No fungal or bacterial infections were noted during the 30-month follow-up period. Conclusions: The results show that lymphocytes (and not granulocytes, platelets, or NK cells) are sensitive to hepatic arterial {sup 90}Yttrium without associated clinical toxicity, and lack of lymphocyte recovery (possibly leading to dysregulation of adaptive cellular immunity) posttherapy indicates poor survival.

  19. The effect of yttrium substitution on the magnetic properties of magnetite nanoparticles

    International Nuclear Information System (INIS)

    Mozaffari, M.; Amighian, J.; Tavakoli, R.

    2015-01-01

    Superparamagnetic Y-substituted magnetite (Y x Fe 3–x O 4 ,with x=0.00, 0.10, 0.15, 0.20 and 0.40) nanoparticles were synthesized via hydrothermal reduction route in the presence of citric acid. The synthesized nanoparticles were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM) and gradient field thermomagnetic measurement. The results showed that a minimum amount of citric acid is required to obtain single phase Y-substituted magnetite nanoparticles. Citric acid acts as a modulator and reducing agent in the formation of spinel structure and controls nanoparticle size and crystallinity. Mean crystallite sizes of the single-phase powders were estimated by Williamson–Hall method. Curie temperature measurement of the samples shows that as yttrium content increases, the Curie temperature decreases. Magnetic measurements show that the saturation magnetization of the samples decreases as x increases up to 0.15 and then increases to x=0.20 and finally decreases again for x=0.40. - Highlights: • Single phase yttrium substituted magnetite nanoparticles were synthesized by hydrothermal-reduction route. • Citric acid plays a key role in reduction of Fe 3+ to Fe 2+ , which is necessary for the formation of magnetite phase. • It is possible to substitute yttrium ions for iron ones as high as x=0.4 by hydrothermal reduction route. • Pure magnetite nanoparticles prepared by this route has a high saturation magnetization. • Yttrium substituted magnetite nanoparticles are superparamagnet at room temperature

  20. Studies on the pressed yttrium oxide-tungsten matrix as a possible dispenser cathode material

    International Nuclear Information System (INIS)

    Yang, Fan; Wang, Jinshu; Liu, Wei; Liu, Xiang; Zhou, Meiling

    2015-01-01

    Yttrium oxide was chosen as the secondary emission substance based on calculation results through first principle theory method. A new kind of pressed yttrium oxide-tungsten matrix dispenser cathodes are prepared by a sol–gel method combined with high temperature sintering in dry hydrogen atmosphere. The results show that the growth of the grains is hampered by the pinning effect of Y 2 O 3 distributing uniformly between the tungsten particles, resulting in the formation of small grain size. It is found that Y 2 O 3 improves the secondary electron emission property, i.e., the secondary emission yield increases with the increase of Y 2 O 3 content in the samples. The maximum secondary emission yield δ max of the cathode with 15% amount of Y 2 O 3 can reach 2.92. Furthermore, the cathode shows a certain thermionic emission performance. The zero field emission current density J 0 of 4.18A/cm 2 has reached at 1050 °C b for this kind of cathode after being activated at 1200 °C b , which are much higher than that of rare earth oxide doped molybdenum (REO-Mo) cathode reported in the previous work. - Highlights: • Yttrium oxide was chosen as the secondary emission substance based on first principle calculation result. • A new kind of cathode has been successfully obtained. • Pressed yttrium oxide-tungsten matrix dispenser cathode exhibits good emission properties. • The improvement of the cathode emission can be well explained by the surface analysis results presented in this work