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Sample records for barium stannate titanate

  1. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    T K Kundu; A Jana; P Barik

    2008-06-01

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the specimen lie in the range 24–40 nm. It is seen that the dielectric permittivity in doped specimens is enhanced by an order of magnitude compared to undoped barium titanate ceramics. The dielectric permittivity shows maxima at 0.3 mole% doping of Fe ion and 0.6 mole% of Ni ion. The unusual dielectric behaviour of the specimens is explained in terms of the change in crystalline structure of the specimens.

  2. Processing science of barium titanate

    Science.gov (United States)

    Aygun, Seymen Murat

    Barium titanate and barium strontium titanate thin films were deposited on base metal foils via chemical solution deposition and radio frequency magnetron sputtering. The films were processed at elevated temperatures for densification and crystallization. Two unifying research goals underpin all experiments: (1) To improve our fundamental understanding of complex oxide processing science, and (2) to translate those improvements into materials with superior structural and electrical properties. The relationships linking dielectric response, grain size, and thermal budget for sputtered barium strontium titanate were illustrated. (Ba 0.6Sr0.4)TiO3 films were sputtered on nickel foils at temperatures ranging between 100-400°C. After the top electrode deposition, the films were co-fired at 900°C for densification and crystallization. The dielectric properties were observed to improve with increasing sputter temperature reaching a permittivity of 1800, a tunability of 10:1, and a loss tangent of less than 0.015 for the sample sputtered at 400°C. The data can be understood using a brick wall model incorporating a high permittivity grain interior with low permittivity grain boundary. However, this high permittivity value was achieved at a grain size of 80 nm, which is typically associated with strong suppression of the dielectric response. These results clearly show that conventional models that parameterize permittivity with crystal diameter or film thickness alone are insufficiently sophisticated. Better models are needed that incorporate the influence of microstructure and crystal structure. This thesis next explores the ability to tune microstructure and properties of chemically solution deposited BaTiO3 thin films by modulation of heat treatment thermal profiles and firing atmosphere composition. Barium titanate films were deposited on copper foils using hybrid-chelate chemistries. An in-situ gas analysis process was developed to probe the organic removal and the

  3. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  4. Electronic structure of nanograin barium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Xiangyun; WANG Xiaohui; LI Dejun; LI Longtu

    2007-01-01

    The density of states and band structure of 20 nm barium titanate(BaTiO3,BT)ceramics are investigated by first-principles calculation.The full potential linearized augmented plane wave(FLAPW)method is used and the exchange correlation effects are treated by the generalized gradient approximation(GGA).The results show that there is substantial hybridization between the Ti 3d and O 2p states in 20 nm BT ceramics and the interaction between barium and oxygen is typically ionic.

  5. Preparation and characterization of barium titanate stannate solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Horchidan, Nadejda, E-mail: NHorchidan@stoner.phys.uaic.ro [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Ianculescu, Adelina C. [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Curecheriu, Lavinia P.; Tudorache, Florin [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Musteata, Valentina [Institute of Macromolecular Chemistry ' Petru Poni' , Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Stoleriu, Stefania [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Dragan, Nicolae; Crisan, Dorel [Institute of Physical Chemistry ' Ilie Murgulescu' , Lab. of Oxide Materials Science, 202 Splaiul Independentei, 060021 Bucharest (Romania); Tascu, Sorin; Mitoseriu, Liliana [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania)

    2011-04-07

    Research highlights: > BaSnxTi1-xO3 (x = 0; 0.05; 0.1; 0.15; 0.2) ceramics were prepared by solid state reaction and sintered at 13000C for 4h. > The phase purity, structural parameters and microstructural characteristics were investigated. > The dielectric properties were studied as function of temperature and frequency and empirical parameters {eta} and {delta} were calcutate. > The non-linear dielectric properties (tunability) of the samples were studied at room temperature. > By increasing the Sn addition, the {epsilon}(E) dependence tends to reduce its hysteresis behaviour. - Abstract: BaSn{sub x}Ti{sub 1-x}O{sub 3} (x = 0; 0.05; 0.1; 0.15; 0.2) solid solutions were prepared via conventional solid state reaction and sintered at 1300 {sup o}C for 4 h, resulting in dense single phase ceramics with homogeneous microstructures. Tetragonal symmetry for x {<=} 0.1, cubic for x = 0.2 and a superposition of tetragonal and cubic for x = 0.15 compositions were found by X-ray diffraction analysis. The temperature and frequency dependence of the complex dielectric constant and dc tunability were determined. A transformation from normal ferroelectric to relaxor with diffuse phase transition was observed with increasing the Sn concentration. All the investigated compositions show a relative tunability between 0.55 (for x = 0.2) and 0.74 (for x = 0.1), at a field amplitude of E = 20 kV/cm.

  6. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO3 single crystals has been studied by means of 18O2/16O2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The data

  7. Electric field induced phase transition of antiferroelectric lead lanthanum zirconate titanate stannate ceramics

    International Nuclear Information System (INIS)

    The electric field induced phase transition behavior of lead lanthanum zirconate titanate stannate (PLZTS) ceramics was investigated. PLZTS undergoes a tetragonal antiferroelectric (AFETet) to rhombohedral ferroelectric (FERh) phase transition with the application of an electric field. The volume increase associated with this antiferroelectric (AFE)endash ferroelectric (FE) phase transition plays an important role with respect to actuator applications. This volume increase involves an increase in both transverse and longitudinal strains. The E field at which the transverse strain increases is accompanied by an abrupt jump in polarization. The longitudinal strain, however, lags behind this polarization jump exhibiting a slight decrease at the onset of phase switching. This decoupling was related to the preferentially oriented AFE domain configuration, with its tetragonal c-axis perpendicular to the applied electric field. It is suggested that phase switching involves multiple steps involving both structural transformation and domain reorientation. copyright 1997 American Institute of Physics

  8. The Novel Formation of Barium Titanate Nanodendrites

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2014-01-01

    Full Text Available The barium titanate (BaTiO3 nanoparticles with novel dendrite-like structures have been successfully fabricated via a simple coprecipitation method, the so-called BaTiO3 nanodendrites (BTNDs. This method was remarkable, fast, simple, and scalable. The growth solution is prepared by barium chloride (BaCl2, titanium tetrachloride (TiCl4, and oxalic acid. The shape and size of BaTiO3 depend on the amount of added BaCl2 solvent. To investigate the influence of amount of BaCl2 on BTNDs, the amount of BaCl2 was varied in the range from 3 to 6 mL. The role of BaCl2 is found to have remarkable influence on the morphology, crystallite size, and formation of dendrite-like structures. The thickness and length of the central stem of BTND were ~300 nm and ~20 μm, respectively. The branchings were found to occur at irregular intervals along the main stem. Besides, the formation mechanism of BTND is proposed and discussed.

  9. Electrorheological behavior of rare earth-doped barium titanate suspensions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Doping Y, La, Ce into barium titanate is found to be able to improve its electrorheological (ER) effect in DC electrical field. The yield stress of a typical doped barium titanate/silicone oil suspension is approximately 3.2 -*7〗kPa at 3.5 -*7〗kV/mm, which is 10 times larger than that of pure barium titanate/silicone oil suspensions. The ER effect increases with the decrease of ionic radius of rare earth (RE) dopant when RE concentration remains constant, and the suspensions exhibit a relatively high shear stress when Y, La, Ce mole fractions are 15%, 10%~15%, and 5%, respectively. Dielectric measurements show that the suitable doping with RE element increases dielectric loss of barium titanate and causes very marked dielectric relaxation at low frequency. By measuring X-ray diffraction patterns of doped barium titanate, it is considered that the occurrence of lattice distortion or defects may be responsible for the change of dielectric properties which results in the improvement of ER effect of barium titanate in DC electrical field.

  10. Liquid-phase-deposited barium titanate thin films on silicon

    International Nuclear Information System (INIS)

    Using a mixture of hexafluorotitanic acid, barium nitrate and boric acid, high refractive index (1.54) barium titanate films can be deposited on silicon substrates. The deposited barium titanate films have featureless surfaces. The deposition temperature is near room temperature (800C). However, there are many fluorine and silicon incorporations in the films. The refractive index of the as-deposited film is 1.54. By current-voltage measurement, the leakage current of the as-deposited film with a thickness of 1000 A is about 9.48x10-7 A cm-2 at the electrical field intensity of 0.3 MV cm-1. By capacitance-voltage measurement, the effective oxide charge of the liquid-phase-deposited barium titanate film is 3.06x1011 cm-2 and the static dielectric constant is about 22. (author)

  11. Effect of compositional variations in the lead lanthanum zirconate stannate titanate system on electrical properties

    International Nuclear Information System (INIS)

    The purpose of this work was to evaluate the effect of compositional modifications on the electrical properties of lead lanthanum zirconate stannate titanate (PLZST) ceramics, as well as to examine their electrically induced phase-change behavior. Variations in the Ti:Sn ratio were evaluated. Increased Ti4+ content produced the following: decreased switching field, related to an increased antiferroelectric-ferroelectric (AFE-FE) transition temperature; constant hysteresis (ΔE) correlated with a constant temperature of the maximum dielectric constant (Tmax); a sharper dielectric-constant maximum peak; and increased room-temperature dielectric constant (K). Variations in the Zr:Sn ratio also were evaluated. Increased Zr4+ content produced the following: increased hysteresis with increased Tmax, decreased maximum dielectric constant, and decreased switching field with increased AFE-FE transition temperature (TAFE-FE). From these results, with respect to compositional modifications, the AFE-FE switching field (EAFE-FE) and ΔE were observed to be dependent strongly on TAFE-FE and Tmax, respectively. Negligible change existed in the strain achievable at the switching field, which remained constant for all compositions at ∼0.16%. The significance of this research was the ability demonstrated to tailor the properties of phase-change materials through compositional modifications

  12. Barium titanate thick films prepared by screen printing technique

    Directory of Open Access Journals (Sweden)

    Mirjana M. Vijatović

    2010-06-01

    Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

  13. Compact pulse forming line using barium titanate ceramic material.

    Science.gov (United States)

    Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008

  14. HYBRID AND CHARACTERISTIC OF POLYANILINE- BARIUM TITANATE NANOCOMPOSITE PARTICLES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Polyaniline-barium titanate (PAn-BaTiO3) ultrafine composite particles were prepared by the oxidative polymerization of aniline with H2O2 while barium titanate nanoparticles were synthesized with a sol-gel method. The infrared spectrogram shows that the polymerization of PAn in the hybrid process of PAn-BaTiO3 is similar with the polymeric process of pure aniline, and there is interaction of PAn and BaTiO3 in the PAn-BaTiO3. SEM and TEM results show that the average diameter of the composite particles is 1.50 μm and the diameters of BaTiO3 nanoparticles are 5-15 nm in the composite particle. The electrical conductivity of the ultrafine composite particles is transformable from 100 to 10-11S/cm by equilibrium doping or dedoping method using various concentration of HCl or NaOH solutions.

  15. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine

    Science.gov (United States)

    Graziana Genchi, Giada; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-01

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these ‘smart’ nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

  16. Electromagnetic properties of carbon black and barium titanate composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guiqin [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)], E-mail: c2b2chen@163.com; Chen Xiaodong; Duan Yuping; Liu Shunhua [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)

    2008-04-24

    Nanocrystalline carbon black/barium titanate compound particle (CP) was synthesized by sol-gel method. The phase structure and morphology of compound particle were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM) and Raman spectrum measurements, the electroconductivity was test by trielectrode arrangement and the precursor powder was followed by differential scanning calorimetric measurements (DSC) and thermal gravimetric analysis (TGA). In addition, the complex relative permittivity and permeability of compound particle were investigated by reflection method. The compound particle/epoxide resin composite (CP/EP) with different contents of CP were measured. The results show barium titanate crystal is tetragonal phase and its grain is oval shape with 80-100 nm which was coated by carbon black film. As electromagnetic (EM) complex permittivity, permeability and reflection loss (RL) shown that the compound particle is mainly a kind of electric and dielectric lossy materials and exhibits excellent microwave absorption performance in the X- and Ku-bands.

  17. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    International Nuclear Information System (INIS)

    Research highlights: → Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) → This is a genuine technique to obtain nanoparticles at low temperature and short times → Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 oC. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba0.8Sr0.2TiO3) nanoparticles (BST) in the temperature range of 100-130 oC. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO3 as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

  18. Study of barium bismuth titanate prepared by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2009-01-01

    Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

  19. Anion and cation diffusion in barium titanate and strontium titanate; Anionen- und Kationendiffusion in Barium- und Strontiumtitanat

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, Markus Franz

    2012-12-19

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO{sub 3} single crystals has been studied by means of {sup 18}O{sub 2}/{sup 16}O{sub 2} isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial

  20. Barium strontium titanate powders prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nm, calculated using Rietveld refinement, is in a good agreement with results of HRTEM

  1. Strain engineered barium strontium titanate for tunable thin film resonators

    Energy Technology Data Exchange (ETDEWEB)

    Khassaf, H.; Khakpash, N. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Sun, F. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States); Sbrockey, N. M.; Tompa, G. S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Kalkur, T. S. [Department of Electrical and Computer Engineering, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States); Alpay, S. P., E-mail: p.alpay@ims.uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-05-19

    Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.

  2. Redox processes in highly yttrium-doped barium titanate

    International Nuclear Information System (INIS)

    The changes of microstructure occurring during oxidation of the reduced form of yttrium-doped barium titanate (Ba1-xYx?Ti1-x4+Tix3+O3) have been studied. Samples were sintered under reduction conditions at PO2=10-4Pa and oxidized by annealing at high temperatures (1150 and 1350 deg. C) in air. Depending on yttrium concentration, the oxidation of the reduced form of the yttrium-doped BaTiO3 caused precipitation of the phase Ba6Ti17O40 or the phases Ba6Ti17O40 and Y2Ti2O7. The precipitates had well-defined orientational relationships with the perovskite matrix. Oxidation of the reduced form of doped barium titanate results in formation of the phase Ba1-xYx?Ti1-x/44+(VTi-bar )x/4O3 responsible for increase in the resistance of outer grain layers, which lie between grain boundaries and grain

  3. Preparation of Barium Titanate Nanopowder through Thermal Decomposition of Peroxide Precursor and Its Formation Mechanism

    Institute of Scientific and Technical Information of China (English)

    PENG, Yangxi; CHEN, Qiyuan; LIU, Shijun

    2009-01-01

    H_2TiO_3 was dissolved in the mixture of hydrogen formed peroxide and ammonia under the pH range of 8-10 with a transparent yellow solution formed. When an equivalent mole of Ba~(2+) solution was added into the yellow solution, the precipitate produced was the peroxide precursor of barium titanate. The cubic nanopowder of barium titanate was obtained when the precipitate was washed, stoved, and then calcined at 600 ℃ for 1 h. The peroxide precursor of barium titanate and barium titanate nanopowder prepared were characterized to be BaTi(H_2O_2)_2O_3 by TGA-DTA, XRD, TEM, SEM, and XREDS. The peroxide precursor of barium titanate was determined to be BaTi(H_2O_2)_2O_3. The particle size of the barium titanate nanopowder, the calcined product of BaTi(H_2O_2)_2O_3, was in the range of 20-40 nm. A formation mechanism of the barium titanate nanopowder through thermal decomposition of its peroxide precursor was proposed and then validated.

  4. Barium titanate core – gold shell nanoparticles for hyperthermia treatments

    Directory of Open Access Journals (Sweden)

    FarrokhTakin E

    2013-06-01

    Full Text Available Elmira FarrokhTakin,1,2 Gianni Ciofani,1 Gian Luigi Puleo,1 Giuseppe de Vito,3,4 Carlo Filippeschi,1 Barbara Mazzolai,1 Vincenzo Piazza,3 Virgilio Mattoli1 1Center for Micro-BioRobotics @SSSA, Fondazione Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy; 2The Biorobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy; 3Center for Nanotechnology Innovation @NEST, Fondazione Istituto Italiano di Tecnologia, Pisa, Italy; 4NEST, Scuola Normale Superiore, Pisa, Italy Abstract: The development of new tools and devices to aid in treating cancer is a hot topic in biomedical research. The practice of using heat (hyperthermia to treat cancerous lesions has a long history dating back to ancient Greece. With deeper knowledge of the factors that cause cancer and the transmissive window of cells and tissues in the near-infrared region of the electromagnetic spectrum, hyperthermia applications have been able to incorporate the use of lasers. Photothermal therapy has been introduced as a selective and noninvasive treatment for cancer, in which exogenous photothermal agents are exploited to achieve the selective destruction of cancer cells. In this manuscript, we propose applications of barium titanate core–gold shell nanoparticles for hyperthermia treatment against cancer cells. We explored the effect of increasing concentrations of these nanoshells (0–100 µg/mL on human neuroblastoma SH-SY5Y cells, testing the internalization and intrinsic toxicity and validating the hyperthermic functionality of the particles through near infrared (NIR laser-induced thermoablation experiments. No significant changes were observed in cell viability up to nanoparticle concentrations of 50 µg/mL. Experiments upon stimulation with an NIR laser revealed the ability of the nanoshells to destroy human neuroblastoma cells. On the basis of these findings, barium titanate core–gold shell nanoparticles resulted in being suitable for hyperthermia treatment

  5. Effect of Nb on barium titanate prepared from citrate solutions

    Directory of Open Access Journals (Sweden)

    Stojanović Biljana D.

    2002-01-01

    Full Text Available The influence of the addition of dopants on the microstructure development and electrical properties of BaTiO3 doped with 0.2, 0.4, 0.6, 0.8 mol% of Nb and 0.01 mol% of Mn based compounds was studied. Doped barium titanate was prepared using the polymeric precursor method from citrate solutions. The powders calcined at 700°C for 4 hours were analysed by infrared (IR spectroscopy to verify the presence of carbonates, and by X-ray diffraction (XRD for phase formation. The phase composition, microstructure and dielectric properties show a strong dependence on the amount of added niobium.

  6. Optical-induced absorption tunability of Barium Strontium Titanate film

    Science.gov (United States)

    Luo, Chunya; Ji, Jie; Yue, Jin; Rao, Yunkun; Yao, Gang; Li, Dan; Zeng, Ying; Li, Renkui; Xiao, Longsheng; Liu, Xinxing; Yao, Jianquan; Ling, Furi

    2016-10-01

    The absorption tunability of 100 nm thickness of ferroelectric Barium Strontium Titanate (Ba0.5Sr0.5TiO3) thin films with different densities of pumped optical field is measured by terahertz time-domain spectroscopy in the range of 0.2 THz - 1.2 THz at 19 °C. Experimental results show that the absorption coefficient of BST film is approximately at 5000 cm-1-20000 cm-1 in the range of 0.2 THz - 1.2 THz and the absorption coefficient reached up to 16% when we applied the optical field up to 600 mW. The theoretical calculations reveal that increasing photoexcitation fluences is responsible for the increasing of transmission change in the conduction current density cause the absorption coefficient varied.

  7. Structural and functional characterization of barium zirconium titanate / epoxy composites

    Directory of Open Access Journals (Sweden)

    Filiberto González Garcia

    2011-12-01

    Full Text Available The dielectric behavior of composite materials (barium zirconium titanate / epoxy system was analyzed as a function of ceramic concentration. Structure and morphologic behavior of the composites was investigated by X-ray Diffraction (XRD, Fourier transformed infrared spectroscopy (FT-IR, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM and transmission electron microscopy (TEM analyses. Composites were prepared by mixing the components and pouring them into suitable moulds. It was demonstrated that the amount of inorganic phase affects the morphology of the presented composites. XRD revealed the presence of a single phase while Raman scattering confirmed structural transitions as a function of ceramic concentration. Changes in the ceramic concentration affected Raman modes and the distribution of particles along into in epoxy matrix. Dielectric permittivity and dielectric losses were influenced by filler concentration.

  8. Study on a flexoelectric microphone using barium strontium titanate

    Science.gov (United States)

    Kwon, S. R.; Huang, W. B.; Zhang, S. J.; Yuan, F. G.; Jiang, X. N.

    2016-04-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.

  9. Characterization and growth dynamics of barium titanate crystallite on nanometer scale

    Institute of Scientific and Technical Information of China (English)

    Sen Wang; Yue Zhang; Zhen Ji; Yousong Gu; Yunhua Huang; Cheng Zhou

    2005-01-01

    Barium titanate powder on nanometer scale was synthesized by means of co-precipitation. The thermal mass loss, crystal grain growth and phase transition of the barium titanate nanometer powder were investigated by TG (Thermogravimetric)-DTA (Differential scanning calorimetric) and XRD (X-ray powder diffractometer) at different heat treatment temperatures. The results show that amorphous barium titanate powder can transfer into tetragonal symmetry structure after heat treatment. When the heat treatment temperature is below 900℃, the grains grow rapidly because the activation energy at low temperature is greatly less than that at high temperature. By controlling theheat treatment temperature, the optimization of the barium titanate crystallite size and formation of tetragonal phase can be realized.

  10. Impact of Biofield Treatment on Atomic and Structural Characteristics of Barium Titanate Powder

    OpenAIRE

    Trivedi, Mahendra; Nayak, Gopal

    2015-01-01

    Barium titanate, perovskite structure is known for its high dielectric constant and piezoelectric properties, which makes it interesting material for fabricating capacitors, transducer, actuator, and sensors. The perovskite crystal structure and lattice vibrations play a crucial role in its piezoelectric and ferroelectric behavior. In the present study, the barium titanate powder was subjected to biofield treatment. Further, the control and treated samples were characterized using X-ray diffr...

  11. Removal of uranyl ions from aqueous solutions using barium titanate

    International Nuclear Information System (INIS)

    Remediation of water sources contaminated with radioactive waste products is a major environmental issue that demands new and more efficient technologies. For this purpose, we report a highly efficient ion-exchange material for the removal of radioactive nuclides from aqueous solutions. The kinetic characteristics of adsorption of uranyl ions on the surface of barium titanate were investigated using a spectrophotometric method under a wide range of conditions. By controlling the pH it was possible to exert fine control over the speciation of uranium, and by optimizing the temperature and grain size of the exchanger, almost total removal was achieved in a matter of just hours. The highest efficiency (>90 % removal) was realized at high temperature (80 deg C). Moreover, the effect of competitive ion adsorption from a range of different cations and anions was quantified. Adsorption was found to follow first-order kinetics and both Freundlich and Langmuir isotherms could be applied to this system. The results of a mathematical treatment of the kinetic data combined with the observation that adsorption was independent of stirring speed and dependent on the ion-exchanger grain size, indicate that the dominant mechanism influencing adsorption is particle spreading. The adsorption behavior was not influenced by exposure to high-intensity gamma radiation, indicating potential for use of this ion-exchanger in systems containing radioactive material. These results will be of use in the development of uranium extraction systems for contaminated water sources. (author)

  12. Properties of barium strontium titanate at millimeter wave frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Osman, Nurul [Department of Physics, Universiti Putra Malaysia (Malaysia); Free, Charles [Department of Engineering and Design, University of Sussex (United Kingdom)

    2015-04-24

    The trend towards using higher millimetre-wave frequencies for communication systems has created a need for accurate characterization of materials to be used at these frequencies. Barium Strontium Titanate (BST) is a ferroelectric material whose permittivity is known to change as a function of applied electric field and have found varieties of application in electronic and communication field. In this work, new data on the properties of BST characterize using the free space technique at frequencies between 145 GHz and 155 GHz for both thick film and bulk samples are presented. The measurement data provided useful information on effective permittivity and loss tangent for all the BST samples. Data on the material transmission, reflection properties as well as loss will also be presented. The outcome of the work shows through practical measurement, that BST has a high permittivity with moderate losses and the results also shows that BST has suitable properties to be used as RAM for high frequency application.

  13. Properties of barium strontium titanate at millimeter wave frequencies

    International Nuclear Information System (INIS)

    The trend towards using higher millimetre-wave frequencies for communication systems has created a need for accurate characterization of materials to be used at these frequencies. Barium Strontium Titanate (BST) is a ferroelectric material whose permittivity is known to change as a function of applied electric field and have found varieties of application in electronic and communication field. In this work, new data on the properties of BST characterize using the free space technique at frequencies between 145 GHz and 155 GHz for both thick film and bulk samples are presented. The measurement data provided useful information on effective permittivity and loss tangent for all the BST samples. Data on the material transmission, reflection properties as well as loss will also be presented. The outcome of the work shows through practical measurement, that BST has a high permittivity with moderate losses and the results also shows that BST has suitable properties to be used as RAM for high frequency application

  14. Dielectric properties of lead zirconate titanate thin films seeded with barium strontium titanate nanoparticles

    International Nuclear Information System (INIS)

    A low temperature synthetic method recently proposed by the authors was applied to the fabrication of lead zirconate titanate (PZT) thin films containing crystalline seeds of barium strontium titanate (BST) nanoparticles. PZT precursor and the BST particles were prepared with complex alkoxide methods. Precursor solution suspending the BST particles was spin-coated on Pt/Ti/SiO2/Si substrate to film thickness of 500-800 nm at particle concentrations of 0-25.1 mol%, and annealed at various temperatures. Seeding of BST particles prevented the formation of pyrochlore phases, which appeared at temperatures above 400 deg. C in unseeded PZT films, and induced crystallization of PZT into perovskite structures at 420 deg. C, which was more than 100 deg. C below the crystallization temperature of the unseeded PZT films. Measurement of dielectric properties at 1 kHz showed that the 25.1 mol% BST-seeded PZT films annealed at 450 deg. C had a dielectric constant as high as 300 with a dissipation factor of 0.05. Leakage current density of the film was less than 1x10-6 A/cm2 at applied electric field from 0 to 64 kV/cm

  15. Highly aligned arrays of high aspect ratio barium titanate nanowires via hydrothermal synthesis

    International Nuclear Information System (INIS)

    We report on the development of a hydrothermal synthesis procedure that results in the growth of highly aligned arrays of high aspect ratio barium titanate nanowires. Using a multiple step, scalable hydrothermal reaction, a textured titanium dioxide film is deposited on titanium foil upon which highly aligned nanowires are grown via homoepitaxy and converted to barium titanate. Scanning electron microscope images clearly illustrate the effect the textured film has on the degree of orientation of the nanowires. The alignment of nanowires is quantified by calculating the Herman's Orientation Factor, which reveals a 58% improvement in orientation as compared to growth in the absence of the textured film. The ferroelectric properties of barium titanate combined with the development of this scalable growth procedure provide a powerful route towards increasing the efficiency and performance of nanowire-based devices in future real-world applications such as sensing and power harvesting

  16. Sputtered Modified Barium Titanate for Thin-Film Capacitor Applications

    Directory of Open Access Journals (Sweden)

    Robert Mamazza

    2012-04-01

    Full Text Available New apparatus and a new process for the sputter deposition of modified barium titanate thin-films were developed. Films were deposited at temperatures up to 900 °C from a Ba0.96Ca0.04Ti0.82Zr0.18O3 (BCZTO target directly onto Si, Ni and Pt surfaces and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and X-ray photoelectron spectroscopy (XPS. Film texture and crystallinity were found to depend on both deposition temperature and substrate: above 600 °C, the as-deposited films consisted of well-facetted crystallites with the cubic perovskite structure. A strongly textured Pt (111 underlayer enhanced the (001 orientation of BCZTO films deposited at 900 °C, 10 mtorr pressure and 10% oxygen in argon. Similar films deposited onto a Pt (111 textured film at 700 °C and directly onto (100 Si wafers showed relatively larger (011 and diminished intensity (00ℓ diffraction peaks. Sputter ambients containing oxygen caused the Ni underlayers to oxidize even at 700 °C: Raising the process temperature produced more diffraction peaks of NiO with increased intensities. Thin-film capacitors were fabricated using ~500 nm thick BCZTO dielectrics and both Pt and Ni top and bottom electrodes. Small signal capacitance measurements were carried out to determine capacitance and parallel resistance at low frequencies and from these data, the relative permittivity (er and resistivity (r of the dielectric films were calculated; values ranged from ~50 to >2,000, and from ~104 to ~1010 Ω∙cm, respectively.

  17. Physical states and properties of barium titanate films in a plane electric field

    Science.gov (United States)

    Shirokov, V. B.; Kalinchuk, V. V.; Shakhovoi, R. A.; Yuzyuk, Yu. I.

    2016-07-01

    The influence of a plane electric field on the phase states of barium titanate thin films under the conditions of forced deformation has been studied. The field dependence of a complete set of material constants has been taken in the region of the c-phase, where polarization losses are absent. The material constants are calculated using equations of the piezoelectric effect derived by linearizing the nonlinear equations of state from the phenomenological; theory for barium titanate. It has been shown that there is a critical value of the field at which the electromechanical coupling coefficient reaches a maximum.

  18. Dielectric properties of piezoelectric 3–0 composites of lithium ferrite/barium titanate

    Indian Academy of Sciences (India)

    P Sarah; S V Suryanarayana

    2003-12-01

    Piezoelectric 3–0 composite ceramics are prepared from a mixture of barium titanate and lithium ferrite phase constituents. Dielectric properties of composites are affected by a number of parameters that include electrical properties, size, shape and amount of constituent phases. The frequency dependent measurements can provide additional insight into mechanisms controlling electrical response. Frequency dependence of dielectric constant plots of lithium ferrite/barium titanate composites will be given and the relevance of trends seen in them will be discussed. Connectivity in composites developed is studied.

  19. A plasmonic modulator based on metal-insulator-metal waveguide with barium titanate core

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2013-01-01

    We design a plasmonic modulator which can be utilized as a compact active device in photonic integrated circuits. The active material, barium titanate (BaTiO3), is sandwiched between metal plates and changes its refractive index under applied voltage. Some degree of switching of ferroelectric...

  20. Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, Y. [Mitsubishi Electric Co., Hyogo (Japan); Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L{sub 2,3} absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features.

  1. Barium strontium titanate thin film varactors for room-temperature microwave device applications

    International Nuclear Information System (INIS)

    Recent progress in the development of barium strontium titanate thin film varactors for room temperature tunable microwave devices applications is reviewed, with emphasis on efforts towards the improvement in the quality of BST thin films and the fabrication issues crucial for the performance of microwave devices based on BST varactors. The paper provides examples of tunable microwave devices employing BST varactors. Other thin film materials currently competing with BST thin films are discussed. Topics which deserve further investigation are suggested. (topical review)

  2. Phase conjugation, isotropic and anisotropic higher order diffraction generation, and image correlation using photorefractive barium titanate

    Science.gov (United States)

    Buranasiri, Prathan

    2005-04-01

    Using barium titanate as the photorefractive material, we demonstrate phase conjugation, beam coupling, higher diffraction order generation. At small incident angles less than 0.015 radian, both codirectional isotropic self-diffraction (CODIS) and contradirectional isotropic self-diffraction (CONDIS) are generated simultaneously. At bigger incident angles approximately more than 0.2094 radian, only codirectional anisotropic-self diffraction (CODAS) are generated. On going imaging correlation is also showing.

  3. Electrical Properties of Thin-Film Capacitors Fabricated Using High Temperature Sputtered Modified Barium Titanate

    OpenAIRE

    Robert Mamazza; Heinz Felzer; Martin Dubs; Glyn J. Reynolds; Martin Kratzer

    2012-01-01

    Simple thin-film capacitor stacks were fabricated from sputter-deposited doped barium titanate dielectric films with sputtered Pt and/or Ni electrodes and characterized electrically. Here, we report small signal, low frequency capacitance and parallel resistance data measured as a function of applied DC bias, polarization versus applied electric field strength and DC load/unload experiments. These capacitors exhibited significant leakage (in the range 8–210 μA/cm2) and dielectric loss. Measur...

  4. A study of the microchemistry of nanocrystalline barium titanate with tetragonal and pseudocubic room temperature symmetries

    Science.gov (United States)

    Lacey, Robert A.

    The investigation of possible effects of undesired surface species on barium titanate, one of the most utilized ferroelectric ceramics, constitutes the focus of this work. Six commercial barium titanate powders from three manufacturers representing two different synthesis processes, with average particle sizes from 40 nm to 470 nm, were analyzed in this study. Four of the nanopowders exhibited pseudocubic room temperature symmetry. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopic analysis of the nanopowders was conducted in ambient atmosphere at room temperature. High temperature DRIFT followed incorporating four avenues of analysis: moisture adsorption studies, deuterium oxide exchange studies, carbon dioxide adsorption studies, and high temperature analysis under dry air and UHP nitrogen atmospheres. At the highest temperature used in this study, 1173K, moisture and the accompanying incorporated protonic impurities were still present. The powders readily readsorbed moisture during rapid cooling, 170K/minute, to room temperature. The smallest powder, as received, formed spherical agglomerates up to 10 mum diameter. These sintered as separate units attaining diameters up to 60 mum during intermediate stage sintering. X-ray photoelectron spectroscopy indicated a surface contamination layer of 10 A to 18 A; 50--70% of which was barium carbonate, the balance being atmospheric adsorbed species. Samples cooled at 3K/minute after an 1173K calcine retained cubic symmetry as indicated with high temperature X-ray diffraction. However, spectral evidence was obtained indicating that upon the rapid cooling from the 1173K calcine, a reorientation to the room temperature tetragonal symmetry was observed. Further, SEM and TEM supported this finding with visual evidence of interfacial rearrangement including corroborating electron diffraction analysis. This data, therefore, substantiated the hypothesis that the cause of the room temperature pseudocubic

  5. Effects of Dysprosium Oxide Doping on Microstructure and Properties of Barium Titanate Ceramic

    Institute of Scientific and Technical Information of China (English)

    Pu Yongping; Ren Huijun; Chen Wei; Chen Shoutian

    2005-01-01

    Different amounts of dysprosium oxide were incorporated into barium titanate powders synthesized by hydrothermal method. Relations of substitution behaviors and lattice parameters with solid-solubility were studied. Furthermore, the influences of dysprosium oxide doping fraction on grain size and dielectric properties of barium titanate ceramic, including dielectric constant and breakdown electric field strength, were investigated via scanning electron microscope, X-ray diffraction and electric property tester. The results show that dysprosium oxide can restrain abnormal grain growth during sintering and that fine-grained and high density of barium titanate ceramic can result in excellent dielectric properties. As mass fraction of dysprosium oxide is 0.6%, the lattice parameters of grain increase to the maximum because of the lowest vacancy concentration. The electric property parameters are cited as following: dielectric constant (25 ℃) reaches 4100, the change in relative dielectric constant with temperature is -10% to 10% within the range of -15~100 ℃, breakdown electric field strength (alternating current) achieves 3.2 kV·mm-1, which can be used in manufacturing high voltage ceramic capacitors.

  6. Hydrothermal Synthesis and Characterization of Europium-dop ed Barium Titanate Nano crys-tallites

    Institute of Scientific and Technical Information of China (English)

    Margarita Garca-Hernandez; Genevieve Chadeyron; Damien Boyer; Antonieta Garca-Murillo; Felipe Carrillo-Romo; Rachid Mahiou

    2013-01-01

    Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chlo-ride and tetrabutyl titanate. Single-crystalline cubic perovskite BaTiO3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the syn-thesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900℃ was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu3+was used as a structural probe, and the luminescence properties recorded from BaTiO3:Eu3+and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles.

  7. Rapid synthesis of barium titanate microcubes using composite-hydroxides-mediated avenue

    Energy Technology Data Exchange (ETDEWEB)

    He, Xi; Ouyang, Jing, E-mail: jingouyang@csu.edu.cn; Jin, Jiao; Yang, Huaming, E-mail: hmyang@csu.edu.cn

    2014-04-01

    Highlights: • Barium titanate oxides microcubes can be synthesized within 1 min. • Composite-hydroxides-mediated strategy provided a possible large scale production. • BST obtained in the strategy showed fairly good crystallinity and tetragonality. - Abstract: This paper reports the rapid synthesis of barium titanate (BaTiO{sub 3}, BTO) microcubes via composite-hydroxides-mediated reaction within 1 min. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectrum (EDS) results confirmed both cubic and tetragonal lattices in the sample and the uniform microcubes with an average size of 1 μm. Ultraviolet–visible (UV–vis) spectrum indicated that the band gap of the BTO powder was 3.05 eV. Ferroelectric polarization vs. electric field (P–E) tests showed that the ferroelectric domains had formed in the as-synthesized BTO microcubes and sintered ceramics. BTO ceramics sintered at 1100 °C for 3 h showed fairly good tetragonality and possessed a maximum polarization of 0.21 μC/cm{sup 2}, indicating that the sintering temperature for the BTO powders prepared via this method was relatively low. The process and equipment reported herein provided a potential method for the rapid synthesis of titanate based perovskites.

  8. Synthesis and characterization of highly-ordered barium-strontium titanate nanotube arrays fabricated by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    Chen Yu; Chen Wei; Guo Feng; Li Mei-Ya; Liu Wei; Zhao Xing-Zhong

    2009-01-01

    Highly uniformed barium-strontium titanate nanotube arrays were fabricated using a porous anodic aluminum oxide template from a barium-strontium titanate sol-gel solution. Electron microscope results showed that nanotubes with uniform length and diameter were obtained. The diameters and lengths of these nanotubes were dependent on the pore diameter and the thickness of the applied anodic aluminum oxide template. High resolution transmission electron microscopy and the selected-area electron diffraction pattern investigations demonstrated the perovskite structure and the polycrystaltine of the fabricated barium-strontium titanate nanotubes. The characterization of the electrical and dielectric properties had also been made. Compared to thin film material,the intrinsic leakage current density is almost the same. Besides,at 30 ℃,the dielectric constant and dielectric loss of the fabricated nanotube is 80 and 0.027 at 1 MHz respectively.

  9. Single-step synthesis of well-crystallized and pure barium titanate nanoparticles in supercritical fluids

    Science.gov (United States)

    Reverón, Helen; Aymonier, Cyril; Loppinet-Serani, Anne; Elissalde, Catherine; Maglione, Mario; Cansell, François

    2005-08-01

    Single-step synthesis of ultra-fine barium titanate powder with a crystallinity as high as 90% and without barium carbonate contamination has been successfully performed under supercritical conditions using a continuous-flow reactor in the temperature range 150-380 °C at 16 MPa. To synthesize this bimetallic oxide, alkoxides, ethanol and water were used. The influence of the synthesis parameters on the BaTiO3 powder characteristics was investigated. The results show that the water to alkoxide precursor ratio, the reactor temperature and the Ba:Ti molar ratio of alkoxide precursor play a major role in the crystallization of pure and well-crystallized BaTiO3 nanoparticles. The continuous mode of operation without post-treatments for powder washing, drying or crystallization increase the industrial interest.

  10. Hydrothermal Synthesis and Processing of Barium Titanate Nanoparticles Embedded in Polymer Films.

    Science.gov (United States)

    Toomey, Michael D; Gao, Kai; Mendis, Gamini P; Slamovich, Elliott B; Howarter, John A

    2015-12-30

    Barium titanate nanoparticles embedded in flexible polymer films were synthesized using hydrothermal processing methods. The resulting films were characterized with respect to material composition, size distribution of nanoparticles, and spatial location of particles within the polymer film. Synthesis conditions were varied based on the mechanical properties of the polymer films, ratio of polymer to barium titanate precursors, and length of aging time between initial formulations of the solution to final processing of nanoparticles. Block copolymers of poly(styrene-co-maleic anhydride) (SMAh) were used to spatially separate titanium precursors based on specific chemical interactions with the maleic anhydride moiety. However, the glassy nature of this copolymer restricted mobility of the titanium precursors during hydrothermal processing. The addition of rubbery butadiene moieties, through mixing of the SMAh with poly(styrene-butadiene-styrene) (SBS) copolymer, increased the nanoparticle dispersion as a result of greater diffusivity of the titanium precursor via higher mobility of the polymer matrix. Additionally, an aminosilane was used as a means to retard cross-linking in polymer-metalorganic solutions, as the titanium precursor molecules were shown to react and form networks prior to hydrothermal processing. By adding small amounts of competing aminosilane, excessive cross-linking was prevented without significantly impacting the quality and composition of the final barium titanate nanoparticles. X-ray diffraction and X-ray photoelectron spectroscopy were used to verify nanoparticle compositions. Particle sizes within the polymer films were measured to be 108 ± 5 nm, 100 ± 6 nm, and 60 ± 5 nm under different synthetic conditions using electron microscopy. Flexibility of the films was assessed through measurement of the glass transition temperature using dynamic mechanical analysis. Dielectric permittivity was measured using an impedance analyzer. PMID

  11. Spectroscopic studies of Nb- and Hf-doped barium titanate crystals

    International Nuclear Information System (INIS)

    One studied the absorption spectra of barium titanate single crystals doped with niobium and hafnium, as well as, those of pure BaTiO3 single crystal. One detected peculiarities both under ferro-paraelectric phase transition at 120 deg C and in paraelectric phase within 150-170 deg C. One observed increase of intensity of λmax = 700 nm band within beyond 150-170 deg C range that was adequate to the increase of number of F-centres

  12. Capacitively coupled electrolyte-conductivity sensor based on high-k material of barium strontium titanate

    OpenAIRE

    Huck, C.; Poghossian, A; Baecker, M; Chaudhuri, S.; Zander, W; Schubert, J.; Begoyan, V. K.; Buniatyan, V. V.; Wagner, Patrick Hermann; Schoening, M. J

    2014-01-01

    A miniaturized capacitively coupled contactless conductivity detection (C4D) sensor based on high-kperovskite oxide of barium strontium titanate (BST) has been implemented for the first time. The BST films(∼120 nm thick) of Ba0.25Sr0.75TiO3composition were prepared on a p-Si-SiO2-Pt structure by pulsed laserdeposition technique using BST targets fabricated by the self-propagating high-temperature synthesismethod. The Pt electrodes were buried into the SiO2layer to obtain a planar structure. F...

  13. Development of a metrology method for composition and thickness of barium strontium titanate thin films

    International Nuclear Information System (INIS)

    Thin films of barium strontium titanate (BST) are being investigated as the charge storage dielectric in advanced memory devices, due to their promise for high dielectric constant. Since the capacitance of BST films is a function of both stoichiometry and thickness, implementation into manufacturing requires precise metrology methods to monitor both of these properties. This is no small challenge, considering the BST film thicknesses are 60 nm or less. A metrology method was developed based on X-ray Fluorescence and applied to the measurement of stoichiometry and thickness of BST thin films in a variety of applications

  14. Screen printed barium titanate thick films prepared from mechanically activated powders

    Energy Technology Data Exchange (ETDEWEB)

    Stojanovic, B.D. [Universidad Estadual Paulista, Sao Paulo (Brazil). Inst. de Quimica; Belgrade Univ. (Yugoslavia). Center for Multidisciplinary Studies; Foschini, C.R.; Varela, J.A. [Universidad Estadual Paulista, Sao Paulo (Brazil). Inst. de Quimica; Pejovic, V.Z. [IRITEL, Belgrade (Yugoslavia); Pavlovic, V.B. [Faculty for Agriculture, Dept. of Physics, UB (Yugoslavia); Pavlovic, V.P. [Faculty for Mechanical Engineering, Dept. of Physics, UB (Yugoslavia)

    2002-07-01

    Barium titanate thick films were prepared from mechanically activated powders based on BaCO{sub 3} and TiO{sub 2}. The thick films were screen-printed on alumina substrates electroded with Ag/Pd. The BT films were sintered at 850 C for 1 hour. The thickness was 30-75 {mu}m depending of number of layers. The microstructure of thick films and the compatibility between BT layers and substrate was investigated by SEM. The dielectric properties were measured and the results were reported. (orig.)

  15. Comparison of barium titanate thin films prepared by inkjet printing and spin coating

    Directory of Open Access Journals (Sweden)

    Jelena Vukmirović

    2015-09-01

    Full Text Available In this paper, barium titanate films were prepared by different deposition techniques (spin coating, office Epson inkjet printer and commercial Dimatix inkjet printer. As inkjet technique requires special rheological properties of inks the first part of the study deals with the preparation of inks, whereas the second part examines and compares structural characteristics of the deposited films. Inks were synthesized by sol-gel method and parameters such as viscosity, particle size and surface tension were measured. Deposited films were examined by optical and scanning electron microscopy, XRD analysis and Raman spectroscopy. The findings consider advantages and disadvantages of the particular deposition techniques.

  16. Properties of composition sinter prepared from fibrous barium titanate and nanometer zirconia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fibrous Batium Titanate particles,30-50 μm long,prepared by a hydrothermal reaction,and the monoclinic phase and nanometer Zirconia,11.6 nm long were prepared by citric acid reaction respectively.Then,the two were composite sintered to produce a new functional material by making full use of crystal-axis orientation of fibers and the activity of nanometer powder.The analydid of composition and microstructure of the new material in terms of XRD and SEM.shows that the solid solution was formed between fibers and nanometer powder,and the distance between lattice(d value)of Barium Titanate changed.But the crystal-axis orientations of fibers remain unchanged.

  17. Dopant Behaviours of Sm2O3 on Microstructure and Properties of Barium Zirconium Titanate Ceramics

    Institute of Scientific and Technical Information of China (English)

    王永力; 李龙土; 齐建全; 桂治轮

    2001-01-01

    The effect of Sm2O3-dopant on the sintering characteristics and dielectric properties of barium zirconium titanate ceramics (BaZrxTi1-xO3) was investigated. It is shown that trace amount of Sm2O3 can greatly affect the grain growth and densification of barium zirconium titanate ceramics during sintering. At the same time, the dielectric peak at high temperature shifts to lower temperature and that at low temperature shifts to higher temperature. The two dielectric peaks overlap with each other when the Sm2O3-dopant content varies from 0.25% to 1%, and the maximum relative dielectric constant is greatly enhanced. These effects may be attributed to the substitution actions of the rare earth element in perovskite lattice. At the doping content of 0.75%, the dielectric constant maximum of 23570 can be obtained. By adopting some proper additives, an excellent Y5V dielective material is obtained, and the room temperature properties are as follows: relative dielectric constant εRT≥23,000, dielectric loss tgδ≤0.0075 and the breakdown strength under alternating field Eb≥5 kV·mm-1.

  18. Influence of preparation route and slip casting conditions on titania and barium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    Arvind K.Nikumbh; Parag V.Adhyapak

    2012-01-01

    Titania (TiO2) and barium titanate (BaTiO3) were synthesized using three different dicarboxylates,which included oxalate,malate and tartarate.These powders were characterized by X-ray powder diffraction,scanning electron micrographs,BET specific surface area and particle size distribution.Their properties depended to a great extent on the nature of the precursor.The titania and barium titanate powders obtained from the tartarate precursor were found to be good for slip casting.Slips of these oxides with different solids contents were prepared at different pH values using both distilled water and ethanol as the dispersing agent and also with and without deflocculant.The theological behaviors of the suspensions were then determined,and the slip,green and sedimentation bulk densities were measured.The minimum viscosities were observed at pH 8.2 for the TiO2-water and pH 10.2 for the BaTiO3-water system.

  19. Synthesis of nanosized barium titanate/epoxy resin composites and measurement of microwave absorption

    Indian Academy of Sciences (India)

    M Murugan; V K Kokate; M S Bapat; A M Sapkal

    2010-12-01

    Barium titanate/epoxy resin composites have been synthesized and tested for microwave absorption/transmission. Nanocrystalline barium titanate (BaTiO3 or BT) was synthesized by the hydrothermal method and the composites of BT/epoxy resin were fabricated as thin solid slabs of four different weight ratios. BT was obtained in the cubic phase with an average particle size of 21 nm, deduced from the X-ray diffraction data. The reflection loss (RL) and transmission loss (TL) of the composite materials were measured by the reflection/transmission method using a vector network analyser R&S: ZVA40, in the frequency range 8.0–18.5 GHz (X and Ku-bands). The RL was found to be better than −10 dB over wide frequency bands. The higher RL for lower concentration of BT could be due to increase in impedance matching effects. Low TL values indicate that the absorption by BT is quite low. This could be due to formation of BT in the cubic paraelectric phase.

  20. Mapping of strain mechanisms in barium titanate by three-dimensional X-ray diffraction

    DEFF Research Database (Denmark)

    Majkut, Marta

    This thesis presents an in-situ three-dimensional study of the grain-scale response of a prototypical piezoelectric ceramic, barium titanate (BT), to an exernally applied electric field. Piezoceramics take advantage of the coupling of electrical and mechanical energies for use in sensors and actu......This thesis presents an in-situ three-dimensional study of the grain-scale response of a prototypical piezoelectric ceramic, barium titanate (BT), to an exernally applied electric field. Piezoceramics take advantage of the coupling of electrical and mechanical energies for use in sensors...... and actuators, found in both common applications such as fuel injectors and specialized applications such as medical imaging equipment. Since piezoceramics are typically used in the polycrystalline state it is important to consider not just the crystal structure but also the role of intergranular effects...... local environment at the cubic to tetragonal transition during processing. When a field is applied, we observe a first-order orientation dependence with second order deviations, again attributed to the grain neighbourhood effect. Corellation of this with microstructural parameters such as grain size...

  1. Experimental investigation of the effect of titanium dioxide and barium titanate additives on DC transient currents in low density polyethylene

    DEFF Research Database (Denmark)

    Khalil, M.S; Henk, Peter O; Henriksen, Mogens;

    1988-01-01

    The effect of titanium dioxide as a semiconductive additive and barium titanate as a highly polar additive on the DC transient currents in low-density polyethylene is investigated. Experiments were made using thick specimens under a high electric field (>25×106 V/m) and a constant temperature of 40...

  2. Barium Titanate Nanoparticles: Highly Cytocompatible Dispersions in Glycol-chitosan and Doxorubicin Complexes for Cancer Therapy

    Science.gov (United States)

    Ciofani, Gianni; Danti, Serena; D'Alessandro, Delfo; Moscato, Stefania; Petrini, Mario; Menciassi, Arianna

    2010-07-01

    In the latest years, innovative nanomaterials have attracted a dramatic and exponentially increasing interest, in particular for their potential applications in the biomedical field. In this paper, we reported our findings on the cytocompatibility of barium titanate nanoparticles (BTNPs), an extremely interesting ceramic material. A rational and systematic study of BTNP cytocompatibility was performed, using a dispersion method based on a non-covalent binding to glycol-chitosan, which demonstrated the optimal cytocompatibility of this nanomaterial even at high concentration (100 μg/ml). Moreover, we showed that the efficiency of doxorubicin, a widely used chemotherapy drug, is highly enhanced following the complexation with BTNPs. Our results suggest that innovative ceramic nanomaterials such as BTNPs can be realistically exploited as alternative cellular nanovectors.

  3. Dielectric property of polyimide/barium titanate composites and its influence factors (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Weidong LIU; Baoku ZHU; Shuhui XIE; Zhikang XU

    2008-01-01

    Using poly(amic acid) (PAA) as a precursor followed by thermal imidization, the polyimide/barium titanate composite films were successfully prepared by a direct mixing method and in situ process. The influence of processing factors, such as particle size, distribution mode and polymerization method on dielectric prop-erties was studied. Results revealed that the dielectric constant (ε) of the composite film increased by using bigger fillers or employing in situ polymerization and bimodal distribution. When the composite film contain-ing 50 Vol-% of BaTiO3 with size in 100 nm was pre-pared via in situ process, its dielectric constant reached 45 at 10 kHz.

  4. Poly (vinylidene fluoride-trifluoroethylene/barium titanate nanocomposite for ferroelectric nonvolatile memory devices

    Directory of Open Access Journals (Sweden)

    Uvais Valiyaneerilakkal

    2013-04-01

    Full Text Available The effect of barium titanate (BaTiO3 nanoparticles (particle size <100nm on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene P(VDF-TrFE copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E hysteresis analysis shows an increase in remnant polarization (Pr and decrease in coercive voltage (Vc. Piezo-response force microscopy analysis shows the switching capability of the polymer composite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memory devices.

  5. Microstructure and blue photoluminescence enhancement of silicon nanoporous pillar array embedded in ferroelectric barium strontium titanate

    International Nuclear Information System (INIS)

    A silicon nanoporous pillar array (Si-NPA) with micrometer/nanometer hierarchical structure was fabricated by hydrothermal etching, followed by spin-coating barium strontium titanate (BST) on Si-NPA substrate. The photoluminescence (PL) spectra of the Si-NPA and BST/Si-NPA thin film were investigated. The emission band of freshly prepared Si-NPA located at ∼630 nm, and a blueshift at ∼425 nm as well as degradation in intensity after annealing at 600 deg. C for 1 h was observed, which might be explained by a quantum confinement effect model. BST ferroelectric material provided a static-electric field and induced the excited carriers in Si-NPA to migrate toward the opposite direction and recombine in an interfacial oxide layer. Therefore, BST enhanced blue emission of Si-NPA as well as passivated Si-NPA

  6. Influence of processing parameters on the structure and properties of barium strontium titanate ceramics

    International Nuclear Information System (INIS)

    Barium strontium titanate (BST) with the molar formula (Ba0.8Sr0.2TiO3) has been prepared by two different processing methods: mixed-oxide (BST-MO) and reaction-sintering (BST-RS). X-ray powder diffraction study shows differences in grain size and crystal symmetry for both these ceramics. The former shows a tetragonal symmetry while the latter presents a cubic symmetry. The occurrence of polar micro-regions associated with the higher chemical non-homogeneous distribution of ion defects from the influence of the processing parameters is the main reason for the higher peak dielectric constant (Km), the higher remanent polarization (Pr), the higher coercive field (Ec), the higher peak current density (Jm), and the lower temperature of peak dielectric constant (Tm) in BST-MO ceramics

  7. Microstructural, dielectric and magnetic properties of multiferroic composite system barium strontium titanate – nickel cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Pahuja, Poonam, E-mail: poonampahuja123@gmail.com; Tandon, R. P., E-mail: ram-tandon@hotmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2015-05-15

    Multiferroic composites (1-x) Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} + (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (where x = 0.1, 0.2, 0.3, 0.4) has been prepared by solid state reaction method. X-ray diffraction analysis of the composite samples confirmed the presence of both barium strontium titanate (BST) and nickel cobalt ferrite (NCF) phases. FESEM images indicated the well dispersion of NCF grains among BST grains. Dielectric constant and loss of the composite samples decreases with increase in frequency following Maxwell-Wagner relaxation mechanism. Composite sample with highest ferrite content possesses highest values of remanent and saturation magnetization.

  8. Ferroelectric domain pattern in barium titanate single crystals studied by means of digital holographic microscopy

    Science.gov (United States)

    Mokrý, Pavel; Psota, Pavel; Steiger, Kateřina; Václavík, Jan; Doleček, Roman; Vápenka, David; Lédl, Vít

    2016-06-01

    In this article, we report on the observation of a ferroelectric domain pattern in the whole volume of the ferroelectric barium titanate single crystal by means of digital holographic microscopy (DHM). Our particular implementation of DHM is based on the Mach–Zehnder interferometer and the numerical processing of data employs the angular spectrum method. A modification of the DHM technique, which allows a fast and accurate determination of the domain walls, i.e. narrow regions separating the antiparallel domains, is presented. Accuracy and sensitivity of the method are discussed. Using this approach, the determination of important geometric parameters of the ferroelectric domain patterns (such as domain spacing or the volume fraction of the anti-parallel domains) is possible. In addition to the earlier DHM studies of domain patterns in lithium niobate and lithium tantalate, our results indicate that the DHM is a convenient method to study a dynamic evolution of ferroelectric domain patterns in all perovskite single crystals.

  9. Multi-parameter sensing using high-k oxide of barium strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Huck, Christina; Poghossian, Arshak; Baecker, Matthias; Schoening, Michael J. [Institute of Nano- and Biotechnologies (INB), FH Aachen, 52428, Juelich (Germany); Peter Gruenberg Institute (PGI-8), Forschungszentrum Juelich GmbH, 52525, Juelich (Germany); Reisert, Steffen; Kramer, Friederike [Institute of Nano- and Biotechnologies (INB), FH Aachen, 52428, Juelich (Germany); Begoyan, Vardges K.; Buniatyan, Vahe V. [Department of Microelectronics and Biomedical Devices, State Engineering University of Armenia, 0009, Yerevan (Armenia)

    2015-06-15

    High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors. In this work, a Si-based sensor chip containing Pt interdigitated electrodes covered with a thin BST layer (485 nm) has been developed for multi-parameter chemical sensing. The chip has been applied for the contactless measurement of the electrolyte conductivity, the detection of adsorbed charged macromolecules (positively charged polyelectrolytes of polyethylenimine) and the concentration of hydrogen peroxide (H{sub 2}O{sub 2}) vapor. The experimental results of functional testing of individual sensors are presented. The mechanism of the BST sensitivity to charged polyelectrolytes and H{sub 2}O{sub 2} vapor has been proposed and discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Structural and Mössbauer investigation on barium titanate-cobalt ferrite composites

    Science.gov (United States)

    Leonel, Liliam V.; Silva, Juliana B.; Albuquerque, Adriana S.; Ardisson, José D.; Macedo, Waldemar A. A.; Mohallem, Nelcy D. S.

    2012-11-01

    Perovskite and spinels oxides have received renewed attention due to the possibility of combining both structures in di-phase composites to obtain multifunctional materials. In this work, barium titanate (perovskite)-cobalt ferrite (spinel) composite powders with different microstructures were obtained from thermal treatment of amorphous precursors at 500-1100 °C. The precursors were prepared by combining coprecipitation and sol-gel routes. Lyophilization of ferrite prior to mixing was used as a strategy to control interphase reaction. Mössbauer spectroscopy showed that the dispersion of coprecipitated ferrite in a viscous BaTiO3 precursor gel resulted in superparamagnetic behavior and reduction of the local magnetic field of site [B].

  11. Optimized growth and dielectric properties of barium titanate thin films on polycrystalline Ni foils

    Institute of Scientific and Technical Information of China (English)

    Liang Wei-Zheng; Ji Yan-Da; Nan Tian-Xiang; Huang Jiang; Zeng Hui-Zhong; Du Hui; Chen Chong-Lin; Lin Yuan

    2012-01-01

    Barium titanate (BTO) thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition (PAD) technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr ~ 400 and tanδ < 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.

  12. Study of grain boundary tunneling in barium-titanate ceramic films

    CERN Document Server

    Wong, H; Poon, M C

    1999-01-01

    The temperature and the electric-field dependences of the current-voltage characteristics and the low-frequency noise of barium-titanate ceramic films are studied. An abnormal field dependence is observed in the resistivity of BaTiO sub 3 materials with a small average grain size. In addition, experiments show that the low-frequency noise behaviors are governed by grain-boundary tunneling at room temperature and by trapping-detrapping of grain-boundary states at temperatures above the Curie point. Physical models for the new observations are developed. Results suggest that grain-boundary tunneling of carriers is as important as the double Schottky barrier in the current conduction in BaTiO sub 3 materials with small grain sizes.

  13. Barium Titanate Nanoparticles: Highly Cytocompatible Dispersions in Glycol-chitosan and Doxorubicin Complexes for Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Danti Serena

    2010-01-01

    Full Text Available Abstract In the latest years, innovative nanomaterials have attracted a dramatic and exponentially increasing interest, in particular for their potential applications in the biomedical field. In this paper, we reported our findings on the cytocompatibility of barium titanate nanoparticles (BTNPs, an extremely interesting ceramic material. A rational and systematic study of BTNP cytocompatibility was performed, using a dispersion method based on a non-covalent binding to glycol-chitosan, which demonstrated the optimal cytocompatibility of this nanomaterial even at high concentration (100 μg/ml. Moreover, we showed that the efficiency of doxorubicin, a widely used chemotherapy drug, is highly enhanced following the complexation with BTNPs. Our results suggest that innovative ceramic nanomaterials such as BTNPs can be realistically exploited as alternative cellular nanovectors.

  14. Studies on gas sensing performance of pure and modified barium strontium titanate thick film resistors

    Indian Academy of Sciences (India)

    G H Jain; L A Patil; P P Patil; U P Mulik; K R Patil

    2007-02-01

    Barium strontium titanate ((Ba0.87Sr0.13)TiO3–BST) ceramic powder was prepared by mechanochemical process. The thick films of different thicknesses of BST were prepared by screen-printing technique and gas-sensing performance of these films was tested for various gases. The films showed highest response and selectivity to ammonia gas. The effect of film thickness on gas response was also studied. As prepared BST thick films were surface modified by dipping them into an aqueous solution of titanium chloride (TiCl3) for different intervals of time. Surface modification shifted response to H2S gas suppressing the responses to ammonia and other gases. The surface modification, using dipping process, altered the adsorbate–adsorbent interactions, which gave the unusual sensitivity and selectivity effect. Sensitivity, selectivity, thermal stability, response and recovery time of the sensor were measured and presented.

  15. Investigation of thickness effects on the dielectric constant barium strontium titanate thin films

    CERN Document Server

    Grattan, L J

    2002-01-01

    The collapse in dielectric constant at small thickness commonly observed in ferroelectric thin films was measured and investigated in barium strontium titanate (Ba sub 0 sub . sub 5 Sr sub 0 sub . sub 5 TiO sub 3). The possible mechanisms responsible for this effect are reviewed. Functional measurements were performed on BST thin films, of 7.5 to 950 nm, by incorporating them into capacitor structures with bottom electrodes of strontium ruthenate (SRO) and thermally- evaporated Au top electrodes. A discussion on thin film growth considerations, optimal PLD conditions and the measurement techniques employed in the project is presented. The experimentally determined dielectric constant - thickness profile was fitted using the series capacitor model assuming low dielectric constant interfacial layers in series with the bulk. Consideration of the case where the combined 'dead layer' thickness was close to the total BST thickness revealed that, for this system, the total 'dead layer' thickness had to be less than ...

  16. High energy storage density performance of Ba, Sr-modified lead lanthanum zirconate titanate stannate antiferroelectric ceramics

    International Nuclear Information System (INIS)

    Graphical abstract: Polarization hysteresis (P–E) loops of the (Pb0.85Ba0.08Sr0.03La0.03) (Zr0.74Sn0.22Ti0.04) samples: (a) measured at different applied electric-field and (b) measured at different temperatures is shown. It is typical antiferroelectrics whose remnant polarization is zero. As the remnant polarization of AFE is small and the ceramics are accompanied by the formation of the anti-parallel domain structure, energy stored in PLZST can be effectively released. Thus we calculated the energy density from the P–E loop and obtained the power density was up to 1.2 J/cm3 at 55 °C, and at 45 °C the energy density was ∼1.24 J/cm3. As usual, for bulk ceramics, the switching between the AFE and FE states occurs at lower field. This value is much higher than that reported previously for the PLZT bulk ceramic (0.4 J/cm3). - Highlights: • Ba2+, Sr2+ co-doping caused the Tc of PLZST moved to the lower temperature (Tc ≈ 40 °C). • The ΔE was so smaller, EAF ≈ 90 kV/cm and EFA ≈ 85 kV/cm. • Ba, Sr co-doped PLZST ceramic exhibited slanted P–E loops with a large breakdown field (100 kV/cm). • A high energy density was up to 1.2 J/cm3. - Abstract: (Pb0.85Ba0.08Sr0.03La0.03)(Zr0.74Sn0.22Ti0.04) (Ba, Sr co-doped PLZST) co-doping antiferroelectric (AFE) ceramics with orthorhombic perovskite structure were prepared by the traditional solid state reaction process. It was observed that the doping of barium and strontium caused the Curie temperature of PLZST move to the lower temperature (Tc ≈ 40 °C). Ba, Sr co-doped PLZST AFE ceramics exhibited excellent electrical properties, the AFE to ferroelectric (FE) transition occurred at field EAF ≈ 90 kV/cm, and the transition from FE to AFE occurred at EFA ≈ 85 kV/cm. The maximum relative permittivity was about 4800, occurring at a field near the AFE to FE transition point, with a dielectric loss of 0.006. The samples exhibited small ΔE and slanted hysteresis loops with a large breakdown field of 100 k

  17. Electrical Properties of Thin-Film Capacitors Fabricated Using High Temperature Sputtered Modified Barium Titanate

    Directory of Open Access Journals (Sweden)

    Robert Mamazza

    2012-04-01

    Full Text Available Simple thin-film capacitor stacks were fabricated from sputter-deposited doped barium titanate dielectric films with sputtered Pt and/or Ni electrodes and characterized electrically. Here, we report small signal, low frequency capacitance and parallel resistance data measured as a function of applied DC bias, polarization versus applied electric field strength and DC load/unload experiments. These capacitors exhibited significant leakage (in the range 8–210 μA/cm2 and dielectric loss. Measured breakdown strength for the sputtered doped barium titanate films was in the range 200 kV/cm −2 MV/cm. For all devices tested, we observed clear evidence for dielectric saturation at applied electric field strengths above 100 kV/cm: saturated polarization was in the range 8–15 μC/cm2. When cycled under DC conditions, the maximum energy density measured for any of the capacitors tested here was ~4.7 × 10−2 W-h/liter based on the volume of the dielectric material only. This corresponds to a specific energy of ~8 × 10−3 W-h/kg, again calculated on a dielectric-only basis. These results are compared to those reported by other authors and a simple theoretical treatment provided that quantifies the maximum energy that can be stored in these and similar devices as a function of dielectric strength and saturation polarization. Finally, a predictive model is developed to provide guidance on how to tailor the relative permittivities of high-k dielectrics in order to optimize their energy storage capacities.

  18. Optical behavior of Pr3+-doped barium titanate-calcium titanate material prepared by sol-gel method

    Science.gov (United States)

    Wang, Xiaoyan; Tang, Yanxue; He, Xiyun; Qiu, Pingsun; He, Qizhuang; Peng, Zifei; Sun, Dazhi

    2009-07-01

    Photoluminescence performances of Pr-doped alkaline-earth titanates (Ba,Ca)TiO3 (with rich barium) prepared by a solgel technique are investigated at room temperature. A relatively strong red luminescence is observed in (Ba0.80Ca0.20)TiO3 material when Pr-BaTiO3 material does not exhibit obvious red luminescence. The phenomenon is discussed with respect to the substitute of Ca and the two-photon luminescence effect. The red luminescence is enhanced by a fast thermal treatment. The wavelength range of luminescence near red and infrared light is broadened by the same process as well. These behaviors are ascribed to the randomization of distribution of Ca and Ba at A site in ABO3 perovskite structure. The experimental results provide not only a possible way to develop new materials with pastel visual impression, but also a potential technique to modify photoluminescence properties that can be controlled by external fields because the microscopic structure of BaTiO3, such as electric domains, can be changed by electric field, temperature, and so on.

  19. Low-Temperature Synthesis and Thermodynamic and Electrical Properties of Barium Titanate Nanorods

    Directory of Open Access Journals (Sweden)

    Florentina Maxim

    2015-01-01

    Full Text Available Studies regarding the morphology dependence of the perovskite-type oxides functional materials properties are of recent interest. With this aim, nanorods (NRs and nanocubes (NCs of barium titanate (BaTiO3 have been successfully synthesized via a hydrothermal route at temperature as low as 408 K, employing barium acetate, titanium isopropoxide, and sodium hydroxide as reagents without any surfactant or template. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and X-ray powder diffraction (XRD, used for the morphology and structure analyses, showed that the NRs were formed by an oriented attachment of the NCs building-blocks with 20 nm average crystallites size. The thermodynamic properties represented by the relative partial molar free energies, enthalpies, and entropies of the oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressure of oxygen, indicated that NRs powders have lower oxygen vacancies concentration than the NCs. This NRs characteristic, together with higher tetragonallity of the structure, leads to the enhancement of the dielectric properties of BaTiO3 ceramics. The results presented in this work show indubitably the importance of the nanopowders morphology on the material properties.

  20. Size effects of 109° domain walls in rhombohedral barium titanate single crystals—A molecular statics analysis

    Energy Technology Data Exchange (ETDEWEB)

    Endres, Florian, E-mail: florian.endres@ltm.uni-erlangen.de; Steinmann, Paul, E-mail: paul.steinmann@ltm.uni-erlangen.de [Department of Mechanical Engineering, University of Erlangen - Nuremberg, Paul-Gordan Str. 3, 91052 Erlangen (Germany)

    2016-01-14

    Ferroelectric functional materials are of great interest in science and technology due to their electromechanically coupled material properties. Therefore, ferroelectrics, such as barium titanate, are modeled and simulated at the continuum scale as well as at the atomistic scale. Due to recent advancements in related manufacturing technologies the modeling and simulation of smart materials at the nanometer length scale is getting more important not only to predict but also fundamentally understand the complex material behavior of such materials. In this study, we analyze the size effects of 109° nanodomain walls in ferroelectric barium titanate single crystals in the rhombohedral phase using a recently proposed extended molecular statics algorithm. We study the impact of domain thicknesses on the spontaneous polarization, the coercive field, and the lattice constants. Moreover, we discuss how the electromechanical coupling of an applied electric field and the introduced strain in the converse piezoelectric effect is affected by the thickness of nanodomains.

  1. Site-selective spectroscopy of the solid-state defect chemistry in erbium-doped barium titanate.

    Science.gov (United States)

    Bak, John D; Wright, John C

    2005-10-01

    Erbium-doped barium titanate crystals were studied by laser-induced fluorescence spectroscopy. Thirteen spectroscopically distinct erbium ion sites were found. The relative concentrations of the different sites changed as a function of the crystal and its preparation and treatment. One major site was present in all crystals. The site distribution was changed either by growing codoped crystals with donor (La3+) and acceptor (Sc3+) ions or by changing the temperature and partial pressure of the oxygen in the annealing atmosphere. Equilibrium calculations were done to simulate the defect distributions that result from the charge compensation of the erbium ions. Comparison with the observed dependence of the site spectral intensities indicated that the erbium enters the lattice on barium sites. We assigned the dominant site to an erbium ion on a barium site that is locally compensated by a barium vacancy, whereas the other lower-intensity sites corresponded to erbium ions that are locally compensated by an electron and a more complex center of an erbium, a barium vacancy, and a hole. The spectra of one sample showed that its defects were different and were characteristic of a sample that had not equilibrated. The new sites in this sample were assigned to erbium entering the lattice on a titanium site, which was then locally compensated by an oxygen vacancy or a hole. Heating equilibrated the sample and changed the erbium to a barium site. PMID:16853368

  2. Nanocomposite thin films for miniaturized multi-ayer ceramic capacitors prepared from barium titanate nanoparticle based hybrid solutions

    OpenAIRE

    Schneller, T.; Halder, S; Waser, R.; Pithan, C.; Dornseiffer, J.; Shiratori, Y; Houben, L.; Vyshnavi, N.; Majumber, S.B.

    2011-01-01

    In the present work a flexible approach for the wet chemical processing of nanocomposite functional thin films is demonstrated. Barium titanate (BTO) based nanocomposite thin films for future miniaturized multi-layer ceramic capacitors are chosen as model systems to introduce the concept of "hybrid solutions" which consist of stabile mixtures of reverse micelle derived BTO nanoparticle dispersions and conventional molecular precursor solutions of either the same (BTO:BTO) or a specifically di...

  3. Extended phase homogeneity and electrical properties of barium calcium titanate prepared by the wet chemical methods

    International Nuclear Information System (INIS)

    Ca-substituted BaTiO3 with extended homogeneity range upto ∼50 mol% CaTiO3 have been prepared by three different chemical routes namely carbonate-oxalate (COBCT), gel-carbonate (GCBCT), and gel-to-crystallite conversion (GHBCT) followed by heat treatment above 1150 deg. C. X-ray powder diffraction (XRD) data show continuous decrease in the tetragonal unit cell parameters as well as c0/a0 ratio with CaTiO3 content, which are in accordance with the substitution of smaller sized Ca2+ ions at the barium sites. The microstructure as well as the dielectric properties are greatly influenced by the cationic ratio, α=(Ba+Ca)/Ti. The grain size decreases with CaTiO3 content for the stoichiometric samples (α=1), whereas ultrafine microstructure is observed in the case of off-stoichiometric samples (α>1) for the whole compositional range of CaTiO3 concentrations. Sharper εr-T characteristics at lower calcium content and broader εr-T with decreased εmax, in the higher calcium range are observed in the case of α=1. Whereas nanometer grained ceramics exhibiting diffuse εr-T characteristics are obtained in the case of α>1. The positive temperature coefficient of resistivity (PTCR) is realized for barium calcium titanate ceramics having 0.3 at.% Sb as the donor dopant for higher CaTiO3 (typically 30 mol%) containing samples (α=1), indicating that Ca2+ ions do not behave as acceptors if they were to substitute at the Ti4+ sites. Whereas the off-stoichiometric (α>1) ceramics retained high resistivity, indicative of the Ti-site occupancy for Ca2+ in fine grain ceramics

  4. Preparation of meta-stable phases of barium titanate by Sol-hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Selvaraj, Mahalakshmi [Department of Physics, R.D. Govt. Arts College, Tamilnadu, Sivaganga - 630561 (India); Department of Material Science, School of Chemistry, Madurai Kamaraj University, Tamilnadu Madurai-625 021 (India); Venkatachalapathy, V. [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O Box 1048 Blindern, NO-0316 Oslo (Norway); Mayandi, J., E-mail: pearce@mtu.edu, E-mail: jeyanthinath@yahoo.co.in [Department of Material Science, School of Chemistry, Madurai Kamaraj University, Tamilnadu Madurai-625 021 (India); Department of Materials Science & Engineering, Michigan Technological University (United States); Karazhanov, S. [Department of Solar Energy, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Pearce, J. M., E-mail: pearce@mtu.edu, E-mail: jeyanthinath@yahoo.co.in [Department of Materials Science & Engineering, Michigan Technological University (United States); Department of Electrical & Computer Engineering, Michigan Technological University (United States)

    2015-11-15

    Two low-cost chemical methods of sol–gel and the hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO{sub 3}) nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C) employing barium dichloride (BaCl{sub 2}) and titanium tetrachloride (TiCl{sub 4}) as precursors and sodium hydroxide (NaOH) as mineralizer for synthesis of BaTiO{sub 3} nanopowders. The as-prepared BaTiO{sub 3} powders were investigated for structural characteristics using x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The overall analysis indicates that the hydrothermal conditions create a gentle environment to promote the formation of crystalline phase directly from amorphous phase at the very low processing temperatures investigated. XRD analysis showed phase transitions from cubic - tetragonal - orthorhombic - rhombohedral with increasing synthesis temperature and calculated grain sizes were 34 – 38 nm (using the Scherrer formula). SEM and TEM analysis verified that the BaTiO{sub 3} nanopowders synthesized by this method were spherical in shape and about 114 - 170 nm in size. The particle distribution in both SEM and TEM shows that as the reaction temperature increases from 100 °C to 250 °C, the particles agglomerate. Selective area electron diffraction (SAED) shows that the particles are crystalline in nature. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable (ferroelectric) phases of undoped BaTiO{sub 3} nanopowders can be stabilized by the sol-hydrothermal method.

  5. Preparation of meta-stable phases of barium titanate by Sol-hydrothermal method

    Directory of Open Access Journals (Sweden)

    Mahalakshmi Selvaraj

    2015-11-01

    Full Text Available Two low-cost chemical methods of sol–gel and the hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO3 nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C employing barium dichloride (BaCl2 and titanium tetrachloride (TiCl4 as precursors and sodium hydroxide (NaOH as mineralizer for synthesis of BaTiO3 nanopowders. The as-prepared BaTiO3 powders were investigated for structural characteristics using x-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The overall analysis indicates that the hydrothermal conditions create a gentle environment to promote the formation of crystalline phase directly from amorphous phase at the very low processing temperatures investigated. XRD analysis showed phase transitions from cubic - tetragonal - orthorhombic - rhombohedral with increasing synthesis temperature and calculated grain sizes were 34 – 38 nm (using the Scherrer formula. SEM and TEM analysis verified that the BaTiO3 nanopowders synthesized by this method were spherical in shape and about 114 - 170 nm in size. The particle distribution in both SEM and TEM shows that as the reaction temperature increases from 100 °C to 250 °C, the particles agglomerate. Selective area electron diffraction (SAED shows that the particles are crystalline in nature. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable (ferroelectric phases of undoped BaTiO3 nanopowders can be stabilized by the sol-hydrothermal method.

  6. Barium titanate nanoparticles and hypergravity stimulation improve differentiation of mesenchymal stem cells into osteoblasts

    Directory of Open Access Journals (Sweden)

    Rocca A

    2015-01-01

    Full Text Available Antonella Rocca,1,2 Attilio Marino,1,2 Veronica Rocca,3 Stefania Moscato,4 Giuseppe de Vito,5,6 Vincenzo Piazza,5 Barbara Mazzolai,1 Virgilio Mattoli,1 Thu Jennifer Ngo-Anh,7 Gianni Ciofani1 1Istituto Italiano di Tecnologia, Center for Micro-BioRobotics @SSSA, Pontedera, Italy, 2Scuola Superiore Sant’Anna, The BioRobotics Institute, Pontedera, Italy, 3Università di Pisa, Dipartimento di Ingegneria dell’Informazione, Pisa, Italy, 4Università di Pisa, Dipartimento di Medicina Clinica e Sperimentale, Pisa, Italy, 5Istituto Italiano di Tecnologia, Center for Nanotechnology Innovation @NEST, Pisa, Italy, 6Scuola Normale Superiore, NEST, Pisa, Italy, 7Directorate of Human Spaceflight and Operations, European Space Agency, Noordwijk, the Netherlands Background: Enhancement of the osteogenic potential of mesenchymal stem cells (MSCs is highly desirable in the field of bone regeneration. This paper proposes a new approach for the improvement of osteogenesis combining hypergravity with osteoinductive nanoparticles (NPs.Materials and methods: In this study, we aimed to investigate the combined effects of hypergravity and barium titanate NPs (BTNPs on the osteogenic differentiation of rat MSCs, and the hypergravity effects on NP internalization. To obtain the hypergravity condition, we used a large-diameter centrifuge in the presence of a BTNP-doped culture medium. We analyzed cell morphology and NP internalization with immunofluorescent staining and coherent anti-Stokes Raman scattering, respectively. Moreover, cell differentiation was evaluated both at the gene level with quantitative real-time reverse-transcription polymerase chain reaction and at the protein level with Western blotting.Results: Following a 20 g treatment, we found alterations in cytoskeleton conformation, cellular shape and morphology, as well as a significant increment of expression of osteoblastic markers both at the gene and protein levels, jointly pointing to a substantial

  7. Synthesis, characterization and thermochemistry of Cs-, Rb- and Sr-substituted barium aluminium titanate hollandites

    International Nuclear Information System (INIS)

    Highlights: • Cs-, Rb- and Sr-substituted barium titanate hollandites were synthesized using sol–gel methods. • Chemical compositions were determined by electron microprobe analyses. • Crystal structures were analyzed using powder synchrotron X-ray diffraction coupled with Rietveld refinements. • Enthalpies of formation were measured using high temperature oxide melt solution calorimetry. • Stability relations with respect to BaTiO3 and SrTiO3 perovskites and other oxides were determined. - Abstract: Titanate hollandites are of considerable interest for immobilization of radioactive Cs, its daughter product Ba and related radionuclides Rb and Sr. In this study, we synthesized three hollandites, Ba1.18Cs0.21Al2.44Ti5.53O16, Ba1.17Rb0.19Al2.46Ti5.53O16 and Ba1.14Sr0.10Al2.38Ti5.59O16, using sol–gel methods. Rietveld analysis of synchrotron XRD data shows that they adopt the tetragonal structure (space group I4/m), and their cell parameters increase with increasing cation size (Sr2+ → Rb+ → Cs+). Standard enthalpies of formation of these hollandites were determined from drop solution calorimetric measurements with lead borate as the solvent at 973 K. Their formation enthalpies are similar, consistent with the occurrence of extensive cation substitutions in hollandites. Further energetic analysis with respect to BaTiO3 and SrTiO3 perovskites and other oxides reveals decreased thermodynamic stability from Cs- to Rb- to Sr-hollandite. This trend is consistent with the phase assemblage observed in Synroc, where Cs+, Rb+ and Ba2+ enter into hollandite, whereas Sr2+ occurs in perovskite

  8. Study of the dielectric properties of barium titanate-polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Pant, H.C. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Patra, M.K. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Verma, Aditya [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Vadera, S.R. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Kumar, N. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India)]. E-mail: nkjainjd@yahoo.com

    2006-07-15

    A comparative study of complex dielectric properties has been carried out at the X-band of microwave frequencies of composites of barium titanate (BaTiO{sub 3}) with two different polymer matrices: insulating polyaniline (PANI) powder (emeraldine base) and maleic resin. From these studies, it is observed that the composites of BaTiO{sub 3} with maleic resin show normal composite behavior and the dielectric constant follows the asymmetric Bruggeman model. In contrast, the composites of BaTiO{sub 3} with PANI show an unusual behavior wherein even at a low concentration of PANI (5 wt.%) there is a drastic reduction in the dielectric constant of BaTiO{sub 3}. This behavior of the dielectric constant is explained on the basis of coating of BaTiO{sub 3} particles by PANI which in turn is attributed to the highly surface adsorbing character. The materials have also been characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy and optical microscopy studies.

  9. Microstructural studies of nanocrystalline barium zirconium titanate (BZT) for piezoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Nor Huwaida Janil, E-mail: huwaidajamil@gmail.com; Izzuddin, Izura; Zainuddin, Zalita; Jumali, Mohammad Hafizuddin Haji, E-mail: hafizhj@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)

    2015-09-25

    Lead-free piezoelectric ceramics based on barium titanate (BaTiO{sub 3}) with substitution of Zr{sup 4+} were prepared using sol-gel method. The Ba(Zr{sub x}Ti{sub 1-x})O{sub 3}, (BZT) powders with x = 0.0, 0.1, 0.2 and 0.3 were pressed into pellets and sintered at 1250 °C for 2 h. Focusing on the effect of Zr{sup 4+} substitutions into BaTiO{sub 3} perovskite system, the phase transition and microstructural properties of BZT ceramics were studied using XRD, SEM and EDX spectroscopy. All X-ray diffractograms were fitted using Pawley refinement model. The XRD diffractograms revealed the progressive phase transition from tetragonal to cubic phase as Zr content increased. The crystallite exhibited decreasing trend and was supported by shrinkage in grain size. The EDX analysis confirmed the successful substitution of Ti{sup 4+} with Zr{sup 4+} in BaTiO3 crystal.

  10. Dielectric properties of micropatterns consisting of barium titanate single-crystalline nanocubes

    Science.gov (United States)

    Mimura, Ken-ichi; Kato, Kazumi

    2015-10-01

    Micropatterns of barium titanate nanocube (BT NC) assemblies were fabricated by dip-coating self-assembly using a micropatterned mold made of Si or polyimide (PI). The microstructure of the BT NC assembly in the micropatterned mold made of PI showed the closest packing structure. This result indicated that the polymer wall in the micropatterns is swollen by the organic solvent used in the dip-coating self-assembly process. As a result, this swelling might work effectively for the self-assembly of the NCs with high ordering assisted by capillary force. Moreover, it is clarified that the line-and-space-molds with a taper angle and a large width were more useful for the self-assembly of BT NCs in microtrenches selectively. The micropatterned mold made of PI could be removed by immersing in N-methyl-2-pyrrolidone at 65 °C. The ordered structure was not destroyed during the removal process. Micropatterned BT NC capacitor structures were obtained by this method after sintering at 850 °C. The interfaces of BT NCs were conjugated face-to-face, as shown by the obtained high-resolution transmission electron microscopy (HR-TEM) cross-sectional profiles. This process has a great potential for fabricating patterned assemblies directly on substrates. The dielectric properties of BT NC micropatterned assemblies in micropatterned molds made of Si were also characterized and compared with those of BT NC assemblies on Pt/Si substrates without micropatterning.

  11. Studies on electrophoretically deposited nanostructured barium titanate systems and carrier transport phenomena

    Science.gov (United States)

    Borah, Manjit; Mohanta, Dambarudhar

    2016-06-01

    We report on the development of nanostructured barium titanate (BaTiO3, BT) films on ~200-μm-thick Ag substrates by employing a cathodic electrophoretic deposition (EPD) technique, where solid-state-derived BT nanoparticles are used as the starting material. Structural, morphological and compositional analyses of the as-synthesized BT nanoparticles and films were performed by X-ray diffraction, electron microscopy and energy-dispersive spectroscopy studies. The synthesized nano-BT system has an average crystallite size of ~8.1 nm and a tetragonality ( c/ a) value ~1.003. To reveal current transport mechanism, the BT films possessing microporous structures and surrounded by homogeneously grown islands were assessed in a metal-insulator-metal (MIM) conformation. The forward current conduction was observed to be purely thermionic up to respective voltages of ~1.4 and 2.2 V as for the fresh and 3-day aged samples. On the other hand, direct tunneling (DT)-mediated Ohmic feature was witnessed at a comparatively higher voltage, beyond which Fowler-Nordheim tunneling (FN) dominates in the respective MIM junctions. The magnitude of current accompanied by FN process was observed to be stronger in reverse biasing than that of forward biasing case. The use of microporous BT films can offer new insights as regards regulated tunneling events meant for miniaturized nanoelectronic elements/components.

  12. Dielectric and Ferroelectric Behavior of Bismuth-Doped Barium Titanate Ceramic Prepared by Microwave Sintering

    Science.gov (United States)

    Mahapatra, A.; Parida, S.; Sarangi, S.; Badapanda, T.

    2015-08-01

    Bismuth-doped barium titanate ceramics with the general formula Ba1- x Bi2 x/3TiO3 ( x = 0.0, 0.01, 0.025, 0.05) have been prepared by the solid state reaction technique. The phase formation and structural property of all compositions have been studied by x-ray diffraction (XRD) pattern and Rietveld refinement. XRD pattern reports the single phase tetragonal crystal system with space group of P4mm. All compositions have been sintered at 1100°C in a microwave furnace for 30 min. The variation of dielectric constant with respect to temperature and frequency was studied and it was found that the dielectric constant decreases whereas transition temperature increased with the increase in Bi content. The diffusivity parameter was calculated by the modified Curie-Weiss law and the diffusivity increased with the increase in Bi content. The ferroelectric property was studied by the P-E hysteresis loop and it was observed that the saturation polarization decreased, but the coercive field increased with Bi content. The optical band gap was calculated from UV-Visible spectroscopy and found to decrease with Bi content.

  13. A Search for the Electron EDM using Europium-Barium Titanates

    Science.gov (United States)

    Eckel, Stephen P.

    The discovery of a permanent electric dipole moment (EDM) of a fundamental particle would prove a great discovery in modern physics; such an EDM would violate two or three of the core symmetries of the fundamental forces of nature. Many models that go beyond the standard model of particle physics produce EDMs with magnitudes approaching the level detectable by the next generation of experiments. One possibility for such an experiment involves the use of a solid sample at low temperatures. In a paramagnetic material, the unpaired electrons, if they possess an EDM, can interact with the polarization of the sample and produce a magnetization that can be detected. This dissertation discusses an incarnation of such an experiment based on mixed europium-barium titanates. Such an experiment offers several advantages over other solid-state and atomic EDM searches including larger electron EDM induced interactions and the ability to measure without an applied electric field. This experiment has produced the world's best limit on the electron EDM to date from a solid sample, at |de| < 6.05 × 10-25 ecm (90% confidence limit). While this limit represents an improvement in the realm of solid-state experiments, it is not yet competitive with similar molecular and atomic experiments. However, there are many possibilities that could produce a superior solid-state experiment, and these will be discussed.

  14. Structure and ferroelectric properties of barium titanate films synthesized by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shunhua, E-mail: xiaoshunhua@glite.edu.cn [College of Chemistry and Bioengineering, Guilin University of Technology, Guangxi Key Laboratory of Information Materials, Guilin 541004 (China); Jiang Weifen [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Luo Kun [College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004 (China); Xia Jinhong; Zhang Lin [College of Chemistry and Bioengineering, Guilin University of Technology, Guangxi Key Laboratory of Information Materials, Guilin 541004 (China)

    2011-06-15

    The barium strontium titanate (Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3}, BST) thin films were synthesized by a sol-gel technique on a silicon nanoporous pillar array (Si-NPA) substrate. SEM observation reveals that the as-prepared BST thin film has uniformly covered the inherited pillar-like surface of the Si-NPA substrate. X-ray diffraction analysis indicates that the perovskite phase was able to be generated in the BST film when the annealing temperature was higher than 600 deg. C. The remnant polarization (Pr) and coercive field (Ec) values were also found to increase with the annealing temperature, with the maxima of 4.57 {mu}C cm{sup -2} for Pr and 7.61 kV mm{sup -1} for Ec at 800 deg. C, respectively. The measurement of leakage current density against voltage applied suggested that the BST films are excellent insulators along with fair resistance to breakdown, and the mechanism of leakage current was discussed.

  15. Synthesis, characterization and thermochemistry of Cs-, Rb- and Sr-substituted barium aluminium titanate hollandites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H., E-mail: hxu@lanl.gov [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wu, L. [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, CA 95616 (United States); Zhu, J. [Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Navrotsky, A. [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, CA 95616 (United States)

    2015-04-15

    Highlights: • Cs-, Rb- and Sr-substituted barium titanate hollandites were synthesized using sol–gel methods. • Chemical compositions were determined by electron microprobe analyses. • Crystal structures were analyzed using powder synchrotron X-ray diffraction coupled with Rietveld refinements. • Enthalpies of formation were measured using high temperature oxide melt solution calorimetry. • Stability relations with respect to BaTiO{sub 3} and SrTiO{sub 3} perovskites and other oxides were determined. - Abstract: Titanate hollandites are of considerable interest for immobilization of radioactive Cs, its daughter product Ba and related radionuclides Rb and Sr. In this study, we synthesized three hollandites, Ba{sub 1.18}Cs{sub 0.21}Al{sub 2.44}Ti{sub 5.53}O{sub 16}, Ba{sub 1.17}Rb{sub 0.19}Al{sub 2.46}Ti{sub 5.53}O{sub 16} and Ba{sub 1.14}Sr{sub 0.10}Al{sub 2.38}Ti{sub 5.59}O{sub 16}, using sol–gel methods. Rietveld analysis of synchrotron XRD data shows that they adopt the tetragonal structure (space group I4/m), and their cell parameters increase with increasing cation size (Sr{sup 2+} → Rb{sup +} → Cs{sup +}). Standard enthalpies of formation of these hollandites were determined from drop solution calorimetric measurements with lead borate as the solvent at 973 K. Their formation enthalpies are similar, consistent with the occurrence of extensive cation substitutions in hollandites. Further energetic analysis with respect to BaTiO{sub 3} and SrTiO{sub 3} perovskites and other oxides reveals decreased thermodynamic stability from Cs- to Rb- to Sr-hollandite. This trend is consistent with the phase assemblage observed in Synroc, where Cs{sup +}, Rb{sup +} and Ba{sup 2+} enter into hollandite, whereas Sr{sup 2+} occurs in perovskite.

  16. First-Principles Study of Lattice Dynamics, Structural Phase Transition, and Thermodynamic Properties of Barium Titanate

    Science.gov (United States)

    Zhang, Huai-Yong; Zeng, Zhao-Yi; Zhao, Ying-Qin; Lu, Qing; Cheng, Yan

    2016-08-01

    Lattice dynamics, structural phase transition, and the thermodynamic properties of barium titanate (BaTiO3) are investigated by using first-principles calculations within the density functional theory (DFT). It is found that the GGA-WC exchange-correlation functional can produce better results. The imaginary frequencies that indicate structural instability are observed for the cubic, tetragonal, and orthorhombic phases of BaTiO3 and no imaginary frequencies emerge in the rhombohedral phase. By examining the partial phonon density of states (PDOSs), we find that the main contribution to the imaginary frequencies is the distortions of the perovskite cage (Ti-O). On the basis of the site-symmetry consideration and group theory, we give the comparative phonon symmetry analysis in four phases, which is useful to analyze the role of different atomic displacements in the vibrational modes of different symmetry. The calculated optical phonon frequencies at Γ point for the four phases are in good agreement with other theoretical and experimental data. The pressure-induced phase transition of BaTiO3 among four phases and the thermodynamic properties of BaTiO3 in rhombohedral phase have been investigated within the quasi-harmonic approximation (QHA). The sequence of the pressure-induced phase transition is rhombohedral→orthorhombic→tetragonal→cubic, and the corresponding transition pressure is 5.17, 5.92, 6.65 GPa, respectively. At zero pressure, the thermal expansion coefficient αV, heat capacity CV, Grüneisen parameter γ, and bulk modulus B of the rhombohedral phase BaTiO3 are estimated from 0 K to 200 K.

  17. Charge Carrier Relaxation Study in Glass-Added Barium Titanate Ceramics Using Thermally Stimulated Depolarization Current

    Science.gov (United States)

    Zhang, Qian; Zhang, Yong; Liu, Xiaolin; Song, Xiaozhen; Zhu, Jia; Baturin, Ivan

    2016-08-01

    The depolarization process of glass-added barium titanate (BaTiO3) ceramics with two different glass concentrations was investigated using a thermally stimulated depolarization current (TSDC) technique. The TSDC spectra of the glass-added BaTiO3 ceramics show three peaks. The first sharp peak near the Curie temperature is due to pyroelectric current associated with ferroelectric-paraelectric phase transition. The middle temperature peak at about 200°C showed no dependence on the depolarization current peak position in the polarization field, and the activation energies of this peak were between 0.43 eV and 0.55 eV, which are attributed to the behavior of defect dipoles related to oxygen vacancies within the BaTiO3 grains. Moreover, the high temperature peak at around 300°C indicated that the depolarization current peak position depends on the polarization temperature and decreases with increasing polarization field. The activation energy of this high temperature peak was between 0.78 eV and 0.98 eV, which is similar to the activation energy for the motion of oxygen vacancies in perovskite oxides. The high temperature peak could be attributed to the migration of oxygen vacancies across grain boundaries. In this work we developed a model in which oxygen vacancies that originated from the defect within grains migrated from the anode to the cathode and some were trapped at the grain boundaries. It is presented here and successfully interprets the appearance and behavior of these peaks.

  18. Magnetoelectric coupling of multiferroic chromium doped barium titanate thin film probed by magneto-impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Jyoti, E-mail: shah.jyoti1@gmail.com; Kotnala, Ravinder K., E-mail: rkkotnala@nplindia.org, E-mail: rkkotnala@gmail.com [Multiferroic and Magnetics Laboratory, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2014-04-07

    Thin film of BaTiO{sub 3} doped with 0.1 at. % Cr (Cr:BTO) has been prepared by pulsed laser deposition technique. Film was deposited on Pt/SrTiO{sub 3} substrate at 500 °C in 50 mTorr Oxygen gas pressure using KrF (298 nm) laser. Polycrystalline growth of single phase Cr:BTO thin film has been confirmed by grazing angle X-ray diffraction. Cr:BTO film exhibited remnant polarization 6.4 μC/cm{sup 2} and 0.79 MV/cm coercivity. Magnetization measurement of Cr:BTO film showed magnetic moment 12 emu/cc. Formation of weakly magnetic domains has been captured by magnetic force microscopy. Theoretical impedance equation fitted to experimental data in Cole-Cole plot for thin film in presence of transverse magnetic field resolved the increase in grain capacitance from 4.58 × 10{sup −12} to 5.4 × 10{sup −11} F. Film exhibited high value 137 mV/cm-Oe magneto-electric (ME) coupling coefficient at room temperature. The high value of ME coupling obtained can reduce the typical processing steps involved in multilayer deposition to obtain multiferrocity in thin film. Barium titanate being best ferroelectric material has been tailored to be multiferroic by non ferromagnetic element, Cr, doping in thin film form opens an avenue for more stable and reliable spintronic material for low power magnetoelectric random excess memory applications.

  19. Image correlation using isotropic and anisotropic higher-order generation and mutually pumped phase conjugation in photorefractive barium titanate

    Science.gov (United States)

    Buranasiri, Prathan; Banerjee, Partha P.; Polejaev, Vladimir; Sun, Ching-Cherng

    2003-10-01

    Using two beam coupling geometry, high order copropagating and contrapropagating isotropic and copropagating anisotropic self-diffraction are demonstrated using photorefractive cerium doped barium titanate. At small incident angles, typically less than 0.015 radians, both codirectional isotropic self-diffraction (CODIS) and contradirectional isotropic self-diffraction (CONDIS) orders are generated simultaneously. At larger incident angles, typically approximately more than 0.2094 radians, only codirectional anisotropic-self diffraction (CODAS) orders are generated. Ongoing work on image auto/cross correlation results are also shown.

  20. Electromagnetic wave absorption properties of barium titanate/carbon nanotube hybrid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Melvin, Gan Jet Hong [Interdisciplinary Graduate School of Science and Technology, Shinshu University, Tokida, Ueda 386-8576 (Japan); Ni, Qing-Qing, E-mail: niqq@shinshu-u.ac.jp [Department of Functional Machinery and Mechanics, Shinshu University, Tokida, Ueda 386-8576 (Japan); Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou (China); Natsuki, Toshiaki [Department of Functional Machinery and Mechanics, Shinshu University, Tokida, Ueda 386-8576 (Japan)

    2014-12-05

    Highlights: • BTO/CNT hybrid nanocomposites was prepared by sol–gel method. • BTO/CNT 60 wt.%, t = 1.1 mm showed a minimum reflection loss of ∼−56.5 dB. • Weight fraction and thickness can be manipulated for various absorption bands. - Abstract: Barium titanate/carbon nanotube (BTO/CNT) hybrid nanocomposites were fabricated by sol–gel method. The BTO/CNT hybrid nanomaterials were characterized using X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Raman and X-ray photoelectron spectroscopy. The BTO/CNT hybrid nanomaterials were then loaded in paraffin wax with different weight percentage, and pressed into toroidal shape with thickness of 1.0 mm to evaluate their complex permittivity and complex permeability using vector network analyzer. The reflection loss of the samples was calculated according to their measured complex permittivity and permeability. The minimum reflection loss of the BTO/CNT 60 wt.% hybrid nanocomposites sample with a thickness of 1.0 mm reached 29.6 dB (over 99.9% absorption) at 13.6 GHz, and also exhibited a wide response bandwidth where the frequency bandwidth of the reflection loss of less than −10 dB (over 90% absorption) was from 12.1 to 13.8 GHz. The BTO/CNT 60 wt.% hybrid nanocomposites with thickness of 1.1 mm showed a minimum reflection loss of ∼−56.5 dB (over 99.999% absorption) at 13.2 GHz and was the best absorber when compared with the other samples of different thickness. The reflection loss peak shifted to lower frequency and wider response bandwidth can be obtained as the thickness of the samples increased. The capability to modulate the absorption band of these samples to suit various applications in different frequency bands simply by manipulating their weight percentage and thickness indicates that these hybrid nanocomposites could be a promising electromagnetic wave absorber.

  1. Multicomponent doped barium strontium titanate thin films for tunable microwave applications

    Science.gov (United States)

    Alema, Fikadu Legesse

    In recent years there has been enormous progress in the development of barium strontium titanate (BST) films for tunable microwave applications. However, the properties of BST films still remain inferior compared to bulk materials, limiting their use for microwave technology. Understanding the film/substrate mismatch, microstructure, and stoichiometry of BST films and finding the necessary remedies are vital. In this work, BST films were deposited via radio frequency magnetron sputtering method and characterized both analytically and electrically with the aim of optimizing their properties. The stoichiometry, crystal structure, and phase purity of the films were studied by varying the oxygen partial pressure (OPP) and total gas pressure (TGP) in the chamber. A better stoichiometric match between film and target was achieved when the TGP is high (> 30 mTorr). However, the O2/Ar ratio should be adjusted as exceeding a threshold of 2 mTorr in OPP facilitates the formation of secondary phases. The growth of crystalline film on platinized substrates was achieved only with a lower temperature grown buffer layer, which acts as a seed layer by crystallizing when the temperature increases. Concurrent Mg/Nb doping has significantly improved the properties of BST thin films. The doped film has shown an average tunability of 53%, which is only ˜8 % lower than the value for the undoped film. This drop is associated with the Mg ions whose detrimental effects are partially compensated by Nb ions. Conversely, the doping has reduced the dielectric loss by ˜40 % leading to a higher figure of merit. Moreover, the two dopants ensure a charge neutrality condition which resulted in significant leakage current reduction. The presence of large amounts of empty shallow traps related to Nb Ti localize the free carriers injected from the contacts; thus increase the device control voltage substantially (>10 V). A combinatorial thin film synthesis method based on co-sputtering of two BST

  2. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining; Caracterizacao do po de titanato de bario dopado com ions sodio e potasio com o refinamento de Rietveld

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

  3. Tuned sensitivity towards H{sub 2}S and NH{sub 3} with Cu doped barium strontium titanate materials

    Energy Technology Data Exchange (ETDEWEB)

    Simion, C. E., E-mail: simion@infim.ro; Teodorescu, V. S.; Stănoiu, A. [National Institute of Materials Physics, Atomistilor 105bis, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Sackmann, A. [AG Weimar, Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 15, D-72076 Tübingen (Germany); Ruşti, C. F.; Piticescu, R. M. [National R and D Institute for Non-ferrous and Rare Metals, 102 Biruintei Blvd, Ilfov (Romania)

    2014-11-05

    The different amount of Cu-doped Barium Strontium Titanate (BST) thick film materials have been tested for their gas-sensing performances towards NH{sub 3} and H{sub 2}S under dry and 50% relative humidity (RH) background conditions. The optimum NH{sub 3} sensitivity was attained with 0.1mol% Cu-doped BST whereas the selective detection of H{sub 2}S was highlighted using 5mol% Cu-doped BST material. No cross-sensitivity effects to CO, NO{sub 2}, CH{sub 4} and SO{sub 2} were observed for all tested materials operated at their optimum temperature (200°C) under humid conditions (50% RH). The presence of humidity clearly enhances the gas sensitivity to NH{sub 3} and H{sub 2}S detection.

  4. Photonic crystal cavity embedded barium strontium titanate thin-film rib waveguide prepared by focused ion beam etching

    International Nuclear Information System (INIS)

    A photonic crystal (PC) cavity embedded Ba0.7Sr0.3TiO3 (barium strontium titanate, or BST) rib waveguide, which functions as an optical filter at λ = 1550 nm, is designed using finite-difference time-domain (FDTD) simulation. The PC cavity is composed of two 5-row photonic crystal mirrors, which are formed by air holes (radii 250 nm) arranged in triangular lattice (periodicity 625 nm) in the BST matrix. Calculations suggested that the required cavity length should be 800 nm for the resonant peak to be situated at 1550 nm. Based on this design, PC cavities were fabricated on BST thin-film rib waveguides by focused ion beam etching with satisfactory results. The transmission spectra of the BST thin-film rib waveguides with PC cavities have been measured. The results agreed well with the FDTD simulation.

  5. Brillouin light scattering study of transverse mode coupling in confined yttrium iron garnet/barium strontium titanate multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Bublikov, K. V.; Grishin, S. V.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2015-11-28

    Using the space-resolved Brillouin light scattering spectroscopy we study the transformation of dynamic magnetization patterns in a bilayer multiferroic structure. We show that in the comparison with a single yttrium iron garnet (YIG) film magnetization distribution is transformed in the bilayer structure due to the coupling of waves propagating both in an YIG film (magnetic layer) and in a barium strontium titanate slab (ferroelectric layer). We present a simple electrodynamic model using the numerical finite element method to show the transformation of eigenmode spectrum of confined multiferroic. In particular, we demonstrate that the control over the dynamic magnetization and the transformation of spatial profiles of transverse modes in magnetic film of the bilayer structure can be performed by the tuning of the wavevectors of transverse modes. The studied confined multiferroic stripe can be utilized for fabrication of integrated dual tunable functional devices for magnonic applications.

  6. Synthesis and characterization of barium titanate, doped with europium and neodymium

    International Nuclear Information System (INIS)

    This work aims at synthesize and characterize mixed oxides in Barium Titanium matrix in doping with Neodymium and Europium analyzing thermogravimetric curves, characteristic bands at infrared region of the polymer complex, which are intermediates to mixed oxides, and identify the formation thereof, and the crystallinity using XRD analysis

  7. Dynamic pyroelectric response of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene) and ferroelectric ceramics of barium lead zirconate titanate

    Energy Technology Data Exchange (ETDEWEB)

    Solnyshkin, A.V. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Morsakov, I.M.; Bogomolov, A.A. [Tver State University, Department of Condensed Matter Physics, Tver (Russian Federation); Belov, A.N.; Vorobiev, M.I.; Shevyakov, V.I.; Silibin, M.V. [National Research University ' ' MIET' ' , Department of Intellectual Technical Systems, Zelenograd, Moscow (Russian Federation); Shvartsman, V.V. [University of Duisburg-Essen, Institute for Materials Science, Essen (Germany)

    2015-10-15

    In this work, pyroelectric properties of composite films on the basis of poly(vinylidene fluoride-trifluoroethylene) copolymer with a various level of ferroelectric ceramics inclusions of barium lead zirconate titanate solid solution were investigated by the dynamic method. The composite films were prepared by the solvent cast method. The unusual spike-like dynamic response with a quasi-stationary component was observed. It is supposed that composite films may be effectively used for pyroelectric applications. (orig.)

  8. Simulations of high permittivity materials for 7 T neuroimaging and evaluation of a new barium titanate-based dielectric.

    Science.gov (United States)

    Teeuwisse, W M; Brink, W M; Haines, K N; Webb, A G

    2012-04-01

    High permittivity "dielectric pads" have been shown to increase image quality at high magnetic fields in regions of low radiofrequency transmit efficiency. This article presents a series of electromagnetic simulations to determine the effects of pad size and geometry, relative permittivity value, as well as thickness on the transmit radiofrequency fields for neuroimaging at 7 T. For a 5-mm thick pad, there is virtually no effect on the transmit field for relative permittivity values lower than ∼90. Significant improvements are found for values between 90 and ∼180. If the relative permittivity is increased above ∼180 then areas of very low transmit efficiency are produced. For a 1-cm thick pad, the corresponding numbers are ∼60 and ∼120, respectively. Based upon the findings, a new material (barium titanate, relative permittivity ∼150) is used to produce thin (∼5 mm) dielectric pads which can easily be placed within a standard receive head array. Experimental measurements of transmit sensitivities, as well as acquisition of T(2) - and T 2*-weighted images show the promise of this approach. PMID:22287360

  9. Wafer–to–wafer transfer process of barium strontium titanate for frequency tuning applications using laser pre-irradiation

    International Nuclear Information System (INIS)

    This paper describes laser-assisted film transfer technology for barium strontium titanate (BST) deposited on a sapphire substrate. BST is a promising ferroelectric material for varactors, which are required for frequency-tunable RF applications. However, the deposition temperature of BST (600 ∼ 700 °C) is too high for surface acoustic wave (SAW) substrates. In this study, BST grown on a sapphire substrate at 650 °C was transferred at low temperature (140 °C) to a borosilicate glass substrate as well as a LiTaO3 substrate. The transferred BST films were characterized as tunable capacitors. A key process in the BST film transfer technology is the laser pre-irradiation of a buffer Pt layer beneath BST from the backside of the sapphire substrate to weaken the BST-to-Pt adhesion. The mechanism of delamination at the BST/Pt interface is discussed using a simple 1D heat transfer model. (paper)

  10. An efficient approach to derive hydroxyl groups on the surface of barium titanate nanoparticles to improve its chemical modification ability.

    Science.gov (United States)

    Chang, Shinn-Jen; Liao, Wei-Sheng; Ciou, Ci-Jin; Lee, Jyh-Tsung; Li, Chia-Chen

    2009-01-15

    Highly hydroxylated barium titanate (BaTiO(3)) nanoparticles have been prepared via an easy and gentle approach which oxidizes BaTiO(3) nanoparticles using an aqueous solution of hydrogen peroxide (H(2)O(2)). The hydroxylated BaTiO(3) surface reacts with sodium oleate (SOA) to form oleophilic layers that greatly enhance the dispersion of BaTiO(3) nanoparticles in organic solvents such as tetrahydrofuran, toluene, and n-octane. The results of Fourier transform infrared spectroscopy confirmed that the major functional groups on the surface of H(2)O(2)-treated BaTiO(3) nanoparticles are hydroxyl groups which are chemically active, favoring chemical bonding with SOA. The results of transmission electron microscopy of SOA-modified BaTiO(3) nanoparticles suggested that the oleate molecules were bonded to the surfaces of nanoparticles and formed a homogeneous layer having a thickness of about 2 nm. Furthermore, the improved dispersion capability of the modified BaTiO(3) nanoparticles in organic solvents was verified through analytic results of its settling and rheological behaviors. PMID:18977001

  11. Structure and Rheology of Poloxamine T1107 and Its Nanocomposite Hydrogels with Cyclodextrin-Modified Barium Titanate Nanoparticles.

    Science.gov (United States)

    Serra-Gómez, Rafael; Dreiss, Cécile A; González-Benito, Javier; González-Gaitano, Gustavo

    2016-06-28

    We report the preparation of a nanocomposite hydrogel based on a poloxamine gel matrix (Tetronic T1107) and cyclodextrin (CD)-modified barium titanate (BT) nanoparticles. The micellization and sol-gel behavior of pH-responsive block copolymer T1107 were fully characterized by small-angle neutron scattering (SANS), dynamic light scattering (DLS), and Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy as a function of concentration, pH and temperature. SANS results reveal that spherical micelles in the low concentration regime present a dehydrated core and highly hydrated shell, with a small aggregation number and size, highly dependent on the degree of protonation of the central amine spacer. At high concentration, T1107 undergoes a sol-gel transition, which is inhibited at acidic pH. Nanocomposites were prepared by incorporating CD-modified BT of two different sizes (50 and 200 nm) in concentrated polymer solutions. Rheological measurements show a broadening of the gel region, as well as an improvement of the mechanical properties, as assessed by the shear elastic modulus, G' (up to 200% increase). Initial cytocompatibility studies of the nanocomposites show that the materials are nontoxic with viabilities over 70% for NIH3T3 fibroblast cell lines. Overall, the combination of Tetronics and modified BaTiO3 provides easily customizable systems with promising applications as soft piezoelectric materials. PMID:27245639

  12. Synthesis and Characterization of Barium Titanate Powders by Sol-Gel Method

    International Nuclear Information System (INIS)

    BaTiO3 powders were prepared by the sol gel method starting from soluble precursors of barium and titanium. The synthesized powders were calcined for 2 h at different temperatures ranges from 800 to 1000 degree Celsius. Phase formation, crystal structure and crystallite size of the calcined powders were investigated using the x-ray diffraction (XRD). A scanning electron microscope (SEM) equipped with energy-dispersive x-ray spectroscopy (EDX) was used for determination of morphology and elemental composition. The XRD results showed that BaTiO3 transformed from the (pseudo)cubic to the ferroelectric tetragonal phase with increasing calcination temperature. The purity and crystallite size of BaTiO3 powders were found to increase with increasing calcination temperature in the range of 32 nm to 140 nm. Higher temperatures led to the particle growth and agglomeration. (author)

  13. Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles.

    Science.gov (United States)

    Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

    2016-01-01

    We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT-Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT-Fe3O4 concentration is approximately 33 vol.%. The BT-Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10(-9) S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT-Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT-Fe3O4 hybrid particles. However, the experimental results of the BT-Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT-Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry. PMID:27633958

  14. Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles

    Science.gov (United States)

    Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

    2016-09-01

    We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT–Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT–Fe3O4 concentration is approximately 33 vol.%. The BT–Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10‑9 S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT–Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT–Fe3O4 hybrid particles. However, the experimental results of the BT–Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT–Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry.

  15. Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles.

    Science.gov (United States)

    Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

    2016-01-01

    We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT-Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT-Fe3O4 concentration is approximately 33 vol.%. The BT-Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10(-9) S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT-Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT-Fe3O4 hybrid particles. However, the experimental results of the BT-Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT-Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry.

  16. Effect of sulfur hexafluoride gas and post-annealing treatment for inductively coupled plasma etched barium titanate thin films

    Science.gov (United States)

    Wang, Cong; Li, Yang; Yao, Zhao; Kim, Hong-Ki; Kim, Hyung-Jun; Kim, Nam-Young

    2014-09-01

    Aerosol deposition- (AD) derived barium titanate (BTO) micropatterns are etched via SF6/O2/Ar plasmas using inductively coupled plasma (ICP) etching technology. The reaction mechanisms of the sulfur hexafluoride on BTO thin films and the effects of annealing treatment are verified through X-ray photoelectron spectroscopy (XPS) analysis, which confirms the accumulation of reaction products on the etched surface due to the low volatility of the reaction products, such as Ba and Ti fluorides, and these residues could be completely removed by the post-annealing treatment. The exact peak positions and chemicals shifts of Ba 3d, Ti 2p, O 1 s, and F 1 s are deduced by fitting the XPS narrow-scan spectra on as-deposited, etched, and post-annealed BTO surfaces. Compared to the as-deposited BTOs, the etched Ba 3d 5/ 2 , Ba 3d 3/ 2 , Ti 2p 3/ 2 , Ti 2p 1/ 2 , and O 1 s peaks shift towards higher binding energy regions by amounts of 0.55, 0.45, 0.4, 0.35, and 0.85 eV, respectively. A comparison of the as-deposited film with the post-annealed film after etching revealed that there are no significant differences in the fitted XPS narrow-scan spectra except for the slight chemical shift in the O 1 s peak due to the oxygen vacancy compensation in O2-excessive atmosphere. It is inferred that the electrical properties of the etched BTO film can be restored by post-annealing treatment after the etching process. Moreover, the relative permittivity and loss tangent of the post-annealed BTO thin films are remarkably improved by 232% and 2,695%, respectively.

  17. Low-sintering condenser materials on the basis of barium titanate; Niedrig-sinternde Kondensatorwerkstoffe auf der Basis von Bariumtitanat

    Energy Technology Data Exchange (ETDEWEB)

    Naghib zadeh, Hamid

    2010-07-01

    The main objective of this work was the development of new barium titanate capacitor materials, which fully densified at a sintering temperature of 900 C and exhibit a high and almost temperature-independent dielectric constant as well as low dielectric loss. In order to decrease the sintering temperature of barium titanate from ca. 1300 C to 900 C, addition of various types of sintering aids have been tested. Li-containing sintering additives show the best result concerning densification and dielectric properties. By addition of 2 to 3 wt% (SrO-B{sub 2}O{sub 3}-Li{sub 2}O) -, (ZnO-B{sub 2}O{sub 3}-Li{sub 2}O) - or (LiF-SrCO{sub 3})-additive combinations to commercially available barium titanate powder 95 % of the theoretical density was achieved after sintering at 900 C. The sintered capacitor materials with the above mentioned additive combinations possess high dielectric constants from 1800 to 3590. It is well known that for a high temperature stability of dielectric constant the formation of core-shell structure in a fine-grained microstructure is required (average grain size < 1 {mu}m). For BaTiO{sub 3} samples contained 2 wt% LiF-SrCO{sub 3} is temperature coefficient of capacitance (TCC) relatively low. The TCC in temperature range between 0 C and 80 C is less than {+-} 15%. The formation of the core-shell structure in a fine-grained microstructure of this sample, which is required to have low TCC, was detected by TEM / EDX analyses. The significantly higher TCC for the BaTiO{sub 3} samples contained 3 wt% SrO-B{sub 2}O{sub 3}-Li{sub 2}O is due to the strong grain growth during sintering. To reduce the TCC in this sample Nb{sub 2}O{sub 5}-Co{sub 2}O{sub 3} was added. By addition of 1.5 wt% Nb{sub 2}O{sub 5}-Co{sub 2}O{sub 3} the temperature stability of the dielectric constant could be significantly improved as a result of the grain growth inhibition and the core-shell formation during sintering. For BaTiO{sub 3} samples contained ZnO-B{sub 2}O{sub 3}-Li

  18. An overview on the progresses of high performance barium titanate/polymer composites%高性能钛酸钡/聚合物复合材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    张亮; 肖定全

    2012-01-01

    具有高介电常数(k)的钛酸钡/聚合物复合材料,兼有钛酸钡陶瓷和聚合物的各自优势,是一种有广泛应用前景的电子材料,因而备受关注。综合给出了近5年来高性能钛酸钡/聚合物复合材料的研究进展,分析指出了原材料选择、制备工艺及其对复合材料介电性能的影响,概括介绍了这类复合材料的主要应用,预测展望了其未来的发展趋势。%Barium titanate/polymer composites with high dielectric constant (k) were very promising electronic materials because the composites combined the advantages of barium titanate ceramics and polymers individual- ly. In this paper, the research progresses of high performance barium titanate/polymer composites in recent five years are outlined, the choosing of raw materials and the preparation technologies and their influence on the die- lectric properties of the composites are pointed out, the major applications of the composites are introduced, and the development trend and the future prospect of barium titanate/polymer composites are reviewed.

  19. Study of the effect of ionizing radiation on composites of wood flour in polypropylene matrix using barium titanate as coupling agent

    International Nuclear Information System (INIS)

    The purpose of this work was to study the effects of ionizing radiation on the properties of wood flour composites in polypropylene matrix, using barium titanate as a coupling agent and the reactive monomer tripropylene glycol diacrylate (TPDGA). An electron accelerator was used in the study as the radiation source. The physical properties of virgin compounds and of the polypropylene/wood flour composite, with and without barium titanate and TPDGA addition, were investigated. The composites were developed from the load treatment, which first consisted of incorporating additives to the wood flour reinforcement and after that, the fusion process of polypropylene and composite mixing in a 'calander'. Subsequently, the samples to be irradiated and submitted to thermal and mechanical assays were molded by injection. The mechanical properties (hardness, impact resistance and molten fluidity index (MFI)), as well as the thermal properties (HDT and Vicat) of the composites were determined. The investigated compositions consisted of polypropylene/wood flour, polypropylene/wood flour with barium titanate and polypropylene/wood flour with barium titanate and TPDGA, using different wood flour concentrations of 10 por cent, 15 por cent and 20 por cent in the polypropylene matrix. The samples were separated in groups and irradiated to doses of 10 kGy and 20 kGy in the samples of the essays of traction. Besides these doses, it was also used doses of 15 kGy and 25 kGy to be observed the behavior of the sample of the sample due to the increase of the radiation. These doses were chosen to show that with low doses the composite material presents reticulation, what represents a viable commercial option. There was a reduction of the flow rate for the composites containing wood flour, being this reduction more effective in the presence of TiBa. The superficial treatment using TPDGA monomer influence in the composite samples because it acted as a plastic additive becoming the sample

  20. Short-range order and fractal cluster structure of aggregates of barium titanate microparticles in a composite based on cyano-ethyl ester of polyvinyl alcohol

    Science.gov (United States)

    Krasovskii, A. N.; Novikov, D. V.; Vasina, E. S.; Matveichikova, P. V.; Sychev, M. M.; Rozhkova, N. N.

    2015-12-01

    The distribution of barium titanate (BaTiO3) microparticles in the matrix of cyano-ethyl ester of polyvinyl alcohol and the change in the surface energy upon introduction of shungite carbon nanoclusters into the dielectric composite have been investigated using the methods of scanning electron microscopy and contact angles. The computer processing of the electron microscopy data has demonstrated that the introduction of 0.04% shungite carbon nanoparticles into the composite leads to a decrease in the spatial homogeneity of the quasi-lattice and to an increase in the local density distribution of BaTiO3 microparticles, as well as in the correlation length corresponding to the formation of an infinite cluster of BaTiO3 particles. It has been found that, in this case, the surface energy and dielectric permittivity of the composite extremely increase.

  1. Synthesis of nanoparticles of barium strontium titanate using hydrothermal microwave method; Sintese de nanoparticulas de titanato de bario estroncio utilizando o metodo hidrotermal assistido por microondas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.A.; Souza, A.E.; Teixeira, S.R. [Universidade Estadual Paulista (DFQB/FCT/UNESP), Presidente Prudente, SP (Brazil). Fac. de Ciencia e Tecnologia. Dept. de Fisica, Quimica e Biologia; Moreira, M.L.; Volanti, D.P. [Universidade Federal de Sao Carlos (LiEC/UFSCAR), SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica; Longo, E. [Universidade Estadual Paulista (UNESP/LiEC), Araraquara, SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica

    2009-07-01

    Nanoparticles of barium strontium titanate Ba{sub x}Sr{sub 1}-{sub x}TiO{sub 3} (BST) had been prepared, with x = 0.5, using the hydrothermal method attended by microwaves (HTMW). A solution was prepared using deionized water, barium chloride (BaCl{sub 2}.2H{sub 2}O), strontium chloride (SrCl{sub 2}.6H{sub 2}O), titanium (IV) isopropoxide (C{sub 12}H28O{sub 4}Ti) and potassium hydroxide (KOH). Afterward the solution was heated to 140 deg C in a microwave oven, at a heating rate of 140 deg C/min, and maintained at this temperature for 40 min, under a pressure of 3 to 4 bar. X-ray diffraction (DRX) and field emission scanning electron microscopy (FE-SEM) had been used in the particles characterization. DRX was used to identify the crystallized phases and the images taken from (FE-SEM) show that the material has a wide particle-size distribution with most of them between 10 and 30 nm. (author)

  2. Synthesis of barium titanate crystalline nanoparticles using hydrothermal microwave method; Obtencao de nanoparticulas cristalinas de titanato de bario usando metodo hidrotermal assistido por microondas

    Energy Technology Data Exchange (ETDEWEB)

    Souza, A.E.; Silva, R.A.; Teixeira, S.R. [Universidade Estadual Paulista (DFQB/FCT/UNESP), Presidente Prudente, SP (Brazil). Dept. de Fisica, Quimica e Biologia. Lab. de Compositos e Ceramicas Funcionais; Moreira, M.L. [Universidade Federal de Sao Carlos (LiEC/UFSCAR), SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica; Volanti, D.P.; Longo, E. [Universidade Estadual Paulista (LiEC/UNESP), Araraquara, SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica

    2009-07-01

    The hydrothermal microwave method (HTMW) was used in the synthesis of barium titanate (BaTiO{sub 3}) nanoparticles. The solution was prepared in deionized water by using titanium (IV) isopropoxide (C{sub 12}H{sub 28}O{sub 4}Ti), barium chloride (BaCl{sub 2}.2H{sub 2}O) and potassium hydroxide (KOH). Afterwards it was heated in an adapted conventional microwave oven. The system is composed of a temperature controller with thermocouple, a hermetic camera of reaction made of teflon, a manometer and a safety valve. The solution was heated to 140 deg C, at a 140 deg C/min heating rate, and maintained at this temperature for 40 minutes. The obtained ceramic powder was characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD data confirms the formation of a high crystalline ceramic material with perovskite structure. The FE-SEM images reveal morphologies with dimensions varying from 27 to 54 nm. (author)

  3. Preparation and Characterization on Nano-Sized Barium Titanate Powder Doped with Lanthanum by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900 ℃ and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43.34 nm.

  4. Influence of sintering temperature on microstructures and energy-storage properties of barium strontium titanate glass-ceramics prepared by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jia; Zhang, Yong; Song, Xiaozhen; Zhang, Qian; Yang, Dongliang; Chen, Yongzhou [Beijing Key Laboratory of Fine Ceramics, State Key Laboratory of New Ceramics and Fine Processing, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 (China)

    2015-12-15

    The sol-gel processing, microstructures, dielectric properties and energy-storage properties of barium strontium titanate glass-ceramics over the sintering temperature range of 1000-1150 C were studied. Through the X-ray diffraction result, it is revealed that the crystallinity increases as the sintering temperature increased from 1000 to 1080 C and has reached a steady-state regime above 1100 C. Scanning electron microscopy images showed that with the increase of sintering temperature, the crystal size increased. Dielectric measurements revealed that the increase in the sintering temperature resulted in a significant increase in the dielectric constant, a strong sharpness of the temperature-dependent dielectric response and a pronounced decrease of the temperature of the dielectric maximum. The correlation between charge spreading behavior and activation energies of crystal and glass was discussed by the employment of the impedance spectroscopy studies. As a result of polarization-electric field hysteresis loops, both the charged and discharged densities increased with increasing sintering temperature. And the maximum value of energy storage efficiency was found to occur at 1130 C. Finally, the dependence of released energy and power densities calculated from the discharged current-time (I-t) curves on the sintering temperature was studied. The relationship between the energy storage properties and microstructure was correlated. Polarization-electric field hysteresis loops for the BST glass-ceramics sintered at different temperatures. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Improvement in crystallization and electrical properties of barium strontium titanate thin films by gold doping using metal-organic deposition method

    International Nuclear Information System (INIS)

    The effect of gold (Au) on the crystallization, dielectric constant and leakage current density of barium strontium titanate (BST) thin films was investigated. BST thin films with various gold concentrations were prepared via a metal-organic deposition process. The X-ray diffraction shows enhanced crystallization as well as expanded lattice constants for the gold-doped BST films. Thermal analysis reveals that the gold dopant induces more complete decomposition of precursor for the doped films than those of undoped ones. The leakage current density of BST films is greatly reduced by the gold dopant over a range of biases (1-5 V). The distribution of gold was confirmed by electron energy loss spectroscopy and found to be inside the BST grains, not in the grain-boundaries. Gold acted as a catalyst, inducing the nucleation of crystallites and improving the crystallinity of the structure. Its addition is shown to be associated to the improvement of the electrical properties of BST films

  6. Sputter-etching characteristics of barium-strontium-titanate and bismuth-strontium-tantalate using a surface-wave high-density plasma reactor

    International Nuclear Information System (INIS)

    The etching of barium-strontium-titanate (BST) and bismuth-strontium-tantalate (SBT) deposited using a pulsed laser deposition technique has been investigated using a nonreactive (argon) surface-wave high-density plasma source. The etch rate of the rf-biased thin films was determined as a function of the self-bias voltage, of the magnetic field intensity and of the gas pressure. It was found that high etch rates with a good selectivity over resist can be achieved without any plasma chemistry, provided the plasma is operated in the very low pressure regime (i.e., below 1 mTorr). For SBT, etch rates as high as 3000 Aa/min with a selectivity of 0.2 over HPR-504 photoresist were obtained with self-bias voltages lower than 150 V. It is also found that even though BST and SBT present similar sputter-etching characteristics, SBT is etched about two times faster than BST as a result of the difference in the atomic density of each material

  7. Barium titanate particle model inquiry through effective permittivity measurements and boundary integral equation method based simulations of the BaTiO{sub 3}-epoxy resin composite material

    Energy Technology Data Exchange (ETDEWEB)

    Orlowska, S [Ecole Centrale de Lyon, Centre de Genie Electrique de Lyon, CNRS UMR 5005, 69134 Ecully (France); Beroual, A [Ecole Centrale de Lyon, Centre de Genie Electrique de Lyon, CNRS UMR 5005, 69134 Ecully (France); Fleszynski, J [Institute of Fundamental Electrotechnics and Electrotechnology, University of Technology of Wroclaw, Wroclaw (Poland)

    2002-10-21

    The heterogeneous mixture properties depend on its constituents' characteristics. We examine the effective permittivity of a two-phase composite material made of epoxy resin host matrix and barium titanate (BaTiO{sub 3}) filler for different volume fractions in the matrix. The task we undertake consists in finding a model of BaTiO{sub 3} particles through the computer simulations executed in PHI3D-electric field calculating package, based on the resolution of the Laplace equation using boundary integral equation method. With this aim in view we compare the measured results of the effective permittivity of the BaTiO{sub 3}-epoxy resin composite samples with the simulation results for different BaTiO{sub 3} particle geometric models and for the same experimental conditions, with regard to the given volume fraction of the powder in the matrix. The experimental results are obtained through the measurements with an impedance meter in the range of frequencies from 50 Hz to 1 MHz.

  8. High temperature dielectric relaxation anomaly of Y³⁺ and Mn²⁺ doped barium strontium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shiguang; Mao, Chaoliang, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin, E-mail: maochaoliang@mail.sic.ac.cn, E-mail: xldong@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2014-10-14

    Relaxation like dielectric anomaly is observed in Y³⁺ and Mn²⁺ doped barium strontium titanate ceramics when the temperature is over 450 K. Apart from the conventional dielectric relaxation analysis method with Debye or modified Debye equations, which is hard to give exact temperature dependence of the relaxation process, dielectric response in the form of complex impedance, assisted with Cole-Cole impedance model corrected equivalent circuits, is adopted to solve this problem and chase the polarization mechanism in this paper. Through this method, an excellent description to temperature dependence of the dielectric relaxation anomaly and its dominated factors are achieved. Further analysis reveals that the exponential decay of the Cole distribution parameter n with temperature is confirmed to be induced by the microscopic lattice distortion due to ions doping and the interaction between the defects. At last, a clear sight to polarization mechanism containing both the intrinsic dipolar polarization and extrinsic distributed oxygen vacancies hopping response under different temperature is obtained.

  9. INFLUENCE OF REOXIDATION ON SILICA-CONTAINING BARIUM TITANATE CERAMICS FOR PTCR THERMISTORS PREPARED BY TAPE CASTING

    Directory of Open Access Journals (Sweden)

    Jianqiao Liu

    2016-03-01

    Full Text Available Silica-containing barium-rich BaTiO₃ ceramics for thermistors with a positive temperature coefficient of resistance are prepared by a tape-casting technique. The ceramics are sintered in a reducing atmosphere at low temperatures of 1175-1225°C. The influences of reoxidation are investigated after the reduced ceramics are reoxidized in air at 700-900°C. An anomalous correlation is illustrated between room temperature resistivity and reoxidation temperature. The anomaly results from the ferroelectricity rebuilding mechanism, which includes the spontaneous polarization theory and the ferroelectricity degradation caused by oxygen vacancies. The acceptor-state densities are estimated from the temperature-dependent resistivity. A critical temperature of 750-800°C is concluded for the grain boundary reoxidation.

  10. 简捷水热前驱物技术制备钛酸钡纳米棒与纳米球%Facile Hydrothermal Single-source Approach to Barium Titanate Nanorods and Nanospheres Preparation

    Institute of Scientific and Technical Information of China (English)

    安长华; 王淑涛; 刘春英; 柳云骐

    2006-01-01

    A facile synthesis route has been developed to prepare barium titanate nanoparitcles via a low temperature (120 ℃) hydrothermal decomposition of single-source metal-organic precursor. A mixture of tetramethylam-monium hydroxide (TMAH) and distilled water was used as reaction media, and Barium titanium ethyl-hexano-isoproxide [BaTi(O2CC7H15)(OC3H7)5] was used as precursor. The architecture of products can be selectively controlled from nanorods to nanospheres by adjusting the precursor's concentration in the reaction system. Powder Xray diffraction (XRD) analysis indicated that the products were in cubic phase. Transmission electronic microscopy (TEM) observation showed that the nanospheres were 30~50 nm in diameter, and the nanorods were 5~10 nm in diameter and 100~600 nm in length, respectively. Phase transformation behavior of the as-prepared products was also investigated.

  11. Participation of MicroRNA-34a and RANKL on bone repair induced by poly(vinylidene-trifluoroethylene)/barium titanate membrane.

    Science.gov (United States)

    Lopes, Helena B; Ferraz, Emanuela P; Almeida, Adriana L G; Florio, Pedro; Gimenes, Rossano; Rosa, Adalberto L; Beloti, Marcio M

    2016-09-01

    The poly(vinylidene-trifluoroethylene)/barium titanate (PVDF) membrane enhances in vitro osteoblast differentiation and in vivo bone repair. Here, we hypothesized that this higher bone repair could be also due to bone resorption inhibition mediated by a microRNA (miR)/RANKL circuit. To test our hypothesis, the large-scale miR expression of bone tissue grown on PVDF and polytetrafluoroethylene (PTFE) membranes was evaluated to identify potential RANKL-targeted miRs modulated by PVDF. The animal model used was rat calvarial defects implanted with either PVDF or PTFE. At 4 and 8 weeks, the bone tissue grown on membranes was submitted to a large-scale analysis of miRs by microarray. The expression of miR-34a and some of its targets, including RANKL, were evaluated by real-time polimerase chain reaction and osteoclast activity was detected by tartrate-resistant acid phosphatase (TRAP) staining. Among more than 250 miRs, twelve, including miR-34a, were simultaneously higher expressed (≥2 fold) at 4 and 8 weeks on PVDF. The higher expression of miR-34a was concomitant with a reduced expression of all its evaluated targets, including RANKL. Additionally, more TRAP-positive cells were observed in bone tissue grown on PTFE compared with PVDF in both time points. In conclusion, our results suggest that the higher bone formation induced by PVDF could be, at least in part, triggered by a miR-34a increase and RANKL decrease, which may inhibit osteoclast differentiation and activity, and bone resorption. PMID:27312544

  12. Effect of working pressure and annealing temperature on microstructure and surface chemical composition of barium strontium titanate films grown by pulsed laser deposition

    Indian Academy of Sciences (India)

    Zahra Saroukhani; Nemat Tahmasebi; Seyed Mohammad Mahdavi; Ali Nemati

    2015-10-01

    Barium strontium titanate (BST, Ba1−SrTiO3) thin films have been extensively used in many dielectric devices such as dynamic random access memories (DRAMs). To optimize its characteristics, a microstructural control is essential. In this paper, Ba0.6Sr0.4TiO3 thin film has been deposited on the SiO2/Si substrate by the pulsed laser deposition (PLD) technique at three different oxygen working pressures of 100, 220 and 350 mTorr. Then the deposited thin films at 100 mTorr oxygen pressure were annealed for 50 min in oxygen ambient at three different temperatures: 650, 720 and 800°C. The effect of oxygen working pressure during laser ablation and thermal treatment on the films was investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis methods. X-ray photoelectron spectroscopy analysis was used to determine the surface chemical composition of the samples. The results indicate that the deposited BST film at low working pressure (100 mTorr) in PLD chamber shows a lower surface roughness than other working pressures (220 and 350 mTorr). The as-deposited films show an amorphous structure and would turn into polycrystalline structure at annealing temperature above 650°C. Increase of temperature would cause the formation of cubic and per-ovskite phases, improvement in crystalline peaks and also result in the decomposition of BST at high temperature (above 800°C). In addition, rising of temperature leads to the increase in size of grains and clusters. Therefore more roughness was found at higher temperatures as a result of a more heterogeneous growth and less tensions.

  13. 聚苯胺/钛酸钡复合材料的电磁性能研究%Electromagnetic Properties of Polyaniline/Barium Titanate Composite

    Institute of Scientific and Technical Information of China (English)

    何倩; 黄英; 王娜; 丁晓

    2012-01-01

    通过溶胶-凝胶法制备纳米钛酸钡(BaTiO3),并以十二烷基苯磺酸钠(DBSA)为掺杂剂,通过原位聚合法制备了DBSA掺杂聚苯胺(PANI)/BaTiO3复合材料.通过X射线衍射仪、傅立叶变换红外光谱仪、透射电子显微镜和矢量网络分析仪对复合材料进行了结构和形态表征并研究了其电磁性能.结果表明,复合材料中的PANI与BaTiO3两者之间存在化学键合作用;复合材料的吸波特性随PANI含量的变化而不同,且不是简单的加和效应.当PANI质量分数为25%时,复合材料的电损耗角正切值(tanδ)在频率11.0 GHz附近出现最大值,为0.31;当PANI质量分数为75%时,复合材料的tanδ新出现2个峰值,在11.0 GHz处的tanδ峰值则向高频方向移动,且峰宽达2.0 GHz.%Nano Barium titanate (BaTiO3) was prepared by sol-gel method and dodecylbenzensulfonic acid (DBSA) was adopted as dopant, then polyaniline (PANI) /BaTiO3 composites were prepared by in-situ polymerization method. The structure and morphology of the composites were characterized by X-ray diffratometer, FTIR, TEM and vector analyzer, the electromagnetic properties of the composites were studied also. The results indicated that there was chemical bonding interaction in the composites between PANI and BaTiO3, the microwave absorbing characteristics of the composites were different with the change of PANI content and they were not simple addition effect. When the mass fraction of PANI was 25% and the frequency was about 11.0 GHz, the dielectric loss angle tangent value (tanδ) of the composite was maximum and it was 0.31. When the mass fraction of PANI was 75%, tanδ of the composite had 2 new peak values, besides, the peak value of tanδ correspond to 11.0 GHz shifted to high frequencies and its peak width was 2.0 GHz.

  14. Physical properties and electronic structure of a new barium titanate suboxide Ba{sub 1+δ}Ti{sub 13−δ}O{sub 12} (δ = 0.11)

    Energy Technology Data Exchange (ETDEWEB)

    Rotundu, Costel R.; Jiang, Shan; Ni, Ni [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States); CNSI, University of California Los Angeles, Los Angeles, California 90095 (United States); Deng, Xiaoyu; Kotliar, Gabriel [Department of Physics, Rutgers University, Piscataway, New Jersey 08854 (United States); Qian, Yiting; Hawthorn, David G. [Department of Physics and Astronomy, University of Waterloo, Waterloo N2L 3G1 (Canada); Khan, Saeed [UCLA Molecular Instrumentation Center, University of California Los Angeles, Los Angeles, California 90095 (United States)

    2015-04-01

    The structure, transport, thermodynamic properties, x-ray absorption spectra (XAS), and electronic structure of a new barium titanate suboxide, Ba{sub 1+δ}Ti{sub 13−δ}O{sub 12} (δ = 0.11), are reported. It is a paramagnetic poor metal with hole carriers dominating the transport. Fermi liquid behavior appears at low temperature. The oxidization state of Ti obtained by the XAS is consistent with the metallic Ti{sup 2+} state. Local density approximation band structure calculations reveal the material is near the Van Hove singularity. The pseudogap behavior in the Ti-d band and the strong hybridization between the Ti-d and O-p orbitals reflect the characteristics of the building blocks of the Ti{sub 13} semi-cluster and the TiO{sub 4} quasi-squares, respectively.

  15. Microstructure and dielectric properties of dysprosium-doped barium titanate ceramics Microestrutura e propriedades dielétricas de cerâmicas de titanato de bário dopado com disprósio

    Directory of Open Access Journals (Sweden)

    Y. Pu

    2005-09-01

    Full Text Available The substitution behavior and lattice parameter of barium titanate between solid_solubility with a dopant concentration in the range of 0.25 to 1.5 mol% are studied. The influences of dysprosium-doped fraction on the grain size and dielectric properties of barium titanate ceramic, including dielectric constant and breakdown electric field strength, are investigated via scanning electronic microscopy, X-ray diffraction and electric property tester. The results show that, at a dysprosium concentration of 0.75 mol%, the abnormal grain growth is inhibited and the lattice parameters of grain rise up to the maximum because of the lowest vacancy concentration. In addition, the finegrain and high density of barium titanate ceramic result in its excellent dielectric properties. The relative dielectric constant (25 °C reaches to 4100. The temperature coefficient of the capacitance varies from -10 to 10% within the temperature range of -15 °C -100 °C, and the breakdown electric field strength (alternating current achieves 3.2 kV/mm. These data suggest that our barium titanate could be used in the manufacture of high voltage ceramic capacitors.Foram estudados o comportamento da substituição e o parâmetro de rede de titanato de bário da solubilidade sólida com uma concentração de dopante na faixa 0,25-1,5 mol%. As influências da fração do dopante disprósio no tamanho de grão e nas propriedades dielétricas da cerâmica de titanato de bário, incluindo constante dielétrica e rigidez dielétrica foram investigadas por meio de microscopia eletrônica de varredura, difração de raios X e teste de propriedades elétricas. Os resultados mostram que a uma concentração de disprósio de 0,75 mol% o crescimento anormal de grão é inibido e os parâmetros de rede aumentam até um máximo devido a menor concentração de vacâncias. Além disso, as cerâmicas de grãos pequenos e alta densidade resultam em excelentes propriedades dielétricas. A

  16. Alkaline earth stannates: The next silicon?

    International Nuclear Information System (INIS)

    Semiconductor materials are being used in an increasingly diverse array of applications, with new device concepts being proposed each year for solar cells, flat-panel displays, sensors, memory, and spin transport. This rapid progress of invention outpaces the development of new semiconductor materials with the required properties and performance. In many applications, high carrier mobility at room temperature is required in addition to specific functional properties critical to the device concept. We review recent developments on high mobility stannate perovskite oxide materials and devices

  17. Alkaline earth stannates: The next silicon?

    Directory of Open Access Journals (Sweden)

    Sohrab Ismail-Beigi

    2015-06-01

    Full Text Available Semiconductor materials are being used in an increasingly diverse array of applications, with new device concepts being proposed each year for solar cells, flat-panel displays, sensors, memory, and spin transport. This rapid progress of invention outpaces the development of new semiconductor materials with the required properties and performance. In many applications, high carrier mobility at room temperature is required in addition to specific functional properties critical to the device concept. We review recent developments on high mobility stannate perovskite oxide materials and devices.

  18. Barium Sulfate

    Science.gov (United States)

    Barium sulfate is used to help doctors examine the esophagus (tube that connects the mouth and stomach), stomach, and ... pictures of the inside of the body). Barium sulfate is in a class of medications called radiopaque ...

  19. Synthesis and characterization of barium titanate, doped with europium and neodymium; Sintese e caracterizacao de titanato de bario, dopados com europio e neodimio

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Fernanda L.C.; Cabral, Alciney M.; Silva, Ademir O.; Oliveiro, Joao B.L., E-mail: nanda_louise@yahoo.com.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal (Brazil). Instituto de Quimica

    2013-07-01

    This work aims at synthesize and characterize mixed oxides in Barium Titanium matrix in doping with Neodymium and Europium analyzing thermogravimetric curves, characteristic bands at infrared region of the polymer complex, which are intermediates to mixed oxides, and identify the formation thereof, and the crystallinity using XRD analysis.

  20. 低温水相一步合成钛酸钡:热力学模型化及实验合成研究%Low Temperature One-Step Synthesis of Barium Titanate:Thermodynamic Modeling and Experimental Synthesis

    Institute of Scientific and Technical Information of China (English)

    沈志刚; 李世刚; 刘朝文; 张建文; 陈建峰

    2005-01-01

    A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a Debye-Hiickel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g.,reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified.As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2,TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.

  1. La2O3与Sb2O3掺杂钛酸锶钡陶瓷的介电性能及相变%Dielectric properties and phase transitions of La2O3-and Sb2O3-doped barium strontium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    张晨; 曲远方

    2012-01-01

    The dielectric properties and phase transition characteristics of La2O3-and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated.The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies.It is found that (La,Sb)-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3.Both La3+ ions and Sb3+ ions occupy the A-sites in perovskite lattice.The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content.The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content.The phase transition of (La,Sb)-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration.The temperature corresponding to the dielectric constant maximum of (La,Sb)-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content,which is attributed to the replacement of host ions by the Sb3+ ions.%采用固相法制备La2O3与Sb2O3掺杂的钛酸锶钡陶瓷,研究其介电性能及相变特性.通过X射线衍射法分析体系微观结构并利用扫描电镜观察其表面微观形貌.(La,Sb)共掺杂的钛酸锶钡陶瓷具有典型的钙钛矿结构,且随着Sb2O3掺杂量的增多其平均粒径显著减小.La3+离子以及Sb3+离子均占据钙钛矿晶格的A位.La2O3与Sb2O3添加量的改变显著影响钛酸锶钡基陶瓷的介电常数以及介电损耗.La2O3改性的钛酸锶钡陶瓷其四方-立方相变为二级相变,且居里温度随着La2O3掺杂量的增多向低温方向移动.(La,Sb)共掺杂的钛酸锶

  2. Effects of surrounding powder in sintering process on the properties of Sb and Mn- doped barium-strontium titanate PTCR ceramics

    Directory of Open Access Journals (Sweden)

    Pornsuda Bomlai

    2006-05-01

    Full Text Available In this research, the effects of surrounding powder used during sintering of Sb and Mn doped bariumstrontium titanate (BST ceramics were studied. The ceramic samples were prepared by a conventional mixed-oxide method and placed on different powders during sintering. Phase formation, microstructure and PTCR behavior of the samples were then observed. Microstructures and PTCR behavior varied with the type of surrounding powder, whereas the crystal structure did not change. The surrounding powder has more effects on the shape of the grain than on the size. The grain size of samples was in the range of 5-20 μm. The most uniform grain size and the highest increase of the ratio of ρmax/ρRT were found to be about 106 for samples which had been sintered on Sb-doped BST powder. This value was an order of magnitude greater than for samples sintered on a powder of the equivalent composition to that of the sample pellet.

  3. Fabrication and investigation on properties of barium titanate/titanium carbide/polyimide composite films%钛酸钡/碳化钛/聚酰亚胺三元复合薄膜的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    张大兴

    2013-01-01

    随着微电子工业的不断发展,高介电常数材料的发展已成为制约电子器件微型化、高速化的关键因素之一.本文以钛酸钡核碳化钛为填料,经硅烷偶联剂改性后按一定比例添加到聚酰亚胺中,制备出钛酸钡/碳化钛/聚酰亚胺(BaTiO3/TiC/PI)三元复合薄膜.对复合薄膜的显微结构及性能进行了分析.实验结果表明,无机填料在复合薄膜中具有较好的分散性,说明硅烷偶联剂改性后无机粉体与聚酰亚胺基体的相容性增加.性能测试表明,随着无机填料含量的增加,三元复合薄膜的拉伸强度和断裂伸长率均下降,而导电性能则逐渐提高.%With the development of the microelectronics industry, the development of high dielectric constant materials have become one of the key factors restricting the rapid miniaturization of electronic devices. In this paper, the barium titanate (BaTiO3) and titanium carbide (TiC) are chosen as fillers and added into the polyimide matrix to fabricate the BaTiO3/TiC/PI composite films. The microstructure and properties of the composite films were analyzed. The experimental results showed that the inorganic fillers had a rather good dispersion in the composite film, which should be attributed to the increased compatibility between inorganic powders and polyimide matrix after the inorganic powders were modified by silane coupling agent. The performance test showed that, with the increase of inorganic filler content, the tensile strength and elongation at break of composite films decreased, while the conductivity increase.

  4. The influences of mole composition of strontium (x) on properties of barium strontium titanate (Ba{sub 1−x}Sr{sub x}TiO{sub 3}) prepared by solid state reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Sandi, Dianisa Khoirum; Supriyanto, Agus; Iriani, Yofentina, E-mail: yopen-2005@yahoo.com [Physics Department, Faculty of Mathematics and Natural Science, Sebelas Maret University (Indonesia); Jamaluddin, Anif [Physics Department, Faculty of Teacher Training and Education, Sebelas Maret University (Indonesia)

    2016-02-08

    Barium Strontium Titanate (Ba{sub 1-x}Sr{sub x}TiO{sub 3}) or BST was prepared by solid state reaction method. Raw materials are BaCO{sub 3}, SrCO{sub 3}, and TiO{sub 2}. Those materials are mixed for 8 h, pressed, and sintered at temperature 1200°C for 2 h. Mole composition of Sr (x) was varied to study its influences on structural, morphological, and electrical properties of BST. Variation of (x) are x = 0; x = 0.1; and x = 0.5. XRD patterns showed a single phase of BST, which mean that mixture of raw materials was homogenous. Crystal structure was influenced by x. BaTiO{sub 3} and Ba{sub 0.9}Ti{sub 0.1}TiO{sub 3} have tetragonal crystal structure, while Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} is cubic. The diffraction angle shifted to right side (angle larger) as the increases of x. Crystalline size of BaTiO{sub 3}, Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3}, and Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} are 38.13 nm; 38.62 nm; and 37.13 nm, respectively. SEM images showed that there are still of pores which were influenced by x. Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has densest surface (pores are few and small in size). Sawyer Tower circuit showed that BaTiO{sub 3} and Ba{sub 0.9}Sr{sub 0.1} TiO{sub 3} is ferroelectric, while Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} is paraelectric. The dielectric constants of BaTiO{sub 3}, Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} and Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} at frequency of 1 KHz are 156; 196; and 83, respectively. Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has relatively highest dielectric constant. It is considered that Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has densest surface.

  5. Study of the effect of ionizing radiation on composites of wood flour in polypropylene matrix using barium titanate as coupling agent; Estudo do efeito da radiacao ionizante em compositos de polipropileno/po de madeira usando titanato de bario como agente de acoplagem

    Energy Technology Data Exchange (ETDEWEB)

    Ulloa, Maritza Eliza Perez

    2007-07-01

    The purpose of this work was to study the effects of ionizing radiation on the properties of wood flour composites in polypropylene matrix, using barium titanate as a coupling agent and the reactive monomer tripropylene glycol diacrylate (TPDGA). An electron accelerator was used in the study as the radiation source. The physical properties of virgin compounds and of the polypropylene/wood flour composite, with and without barium titanate and TPDGA addition, were investigated. The composites were developed from the load treatment, which first consisted of incorporating additives to the wood flour reinforcement and after that, the fusion process of polypropylene and composite mixing in a 'calander'. Subsequently, the samples to be irradiated and submitted to thermal and mechanical assays were molded by injection. The mechanical properties (hardness, impact resistance and molten fluidity index (MFI)), as well as the thermal properties (HDT and Vicat) of the composites were determined. The investigated compositions consisted of polypropylene/wood flour, polypropylene/wood flour with barium titanate and polypropylene/wood flour with barium titanate and TPDGA, using different wood flour concentrations of 10 por cent, 15 por cent and 20 por cent in the polypropylene matrix. The samples were separated in groups and irradiated to doses of 10 kGy and 20 kGy in the samples of the essays of traction. Besides these doses, it was also used doses of 15 kGy and 25 kGy to be observed the behavior of the sample of the sample due to the increase of the radiation. These doses were chosen to show that with low doses the composite material presents reticulation, what represents a viable commercial option. There was a reduction of the flow rate for the composites containing wood flour, being this reduction more effective in the presence of TiBa. The superficial treatment using TPDGA monomer influence in the composite samples because it acted as a plastic additive becoming the

  6. Flexoelectricity in barium strontium titanate thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Seol Ryung; Huang, Wenbin; Yuan, Fuh-Gwo; Jiang, Xiaoning, E-mail: xjiang5@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Shu, Longlong [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Electronic Materials Research Laboratory, International Center for Dielectric Research, Xi' an Jiao Tong University, Xi' an, Shaanxi 710049 (China); Maria, Jon-Paul [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-10-06

    Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.

  7. Synthesis of barium-zinc-titanate ceramics

    Directory of Open Access Journals (Sweden)

    Obradović N.

    2012-01-01

    Full Text Available Mixtures of BaCO3, ZnO and TiO2 powders, with molar ratio of 1:2:4, were mechanically activated for 20, 40 and minutes in a planetary ball mill. The resulting powders were compacted into pellets and isothermally sintered at 1250°C for 2h with a heating rate of 10°C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained correlation between thermal diffusivity and experimental conditions, as well the samples microstructure characteristics, was discussed.

  8. High temperature impedance spectroscopy of barium stannate, BaSnO3

    Indian Academy of Sciences (India)

    Shail Upadhyay

    2013-11-01

    Polycrystalline powder of BaSnO3 was prepared at 1300 °C using a high-temperature solid-state reaction technique. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with lattice parameter: = (4.1158 ± 0.0003) Å. The synthesized powder was characterized using X-ray diffraction (XRD) scanning electron micrographs, energy dispersive X-ray analysis, differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50–650 °C and frequency range of 10 Hz–13 MHz. The complex impedance plots at temperature ≥ 300 °C show that total impedance is due to the contributions of grains, grain boundaries and electrode. Resistance of these contributions has been determined. Variation of these resistances with temperature shows the presence of two different regions with different slopes. The nature of variation for the above three resistances, in both the temperature regions confirms that conducting species (phases) responsible for grain, grain boundaries and electrode are the same. Based on the value of activation energy, it is proposed that conduction via hopping of doubly ionized oxygen vacancies ($V^{\\bullet \\bullet}_{o}$) is taking place in the temperature region of 300–450 °C, whereas in the temperature region of 450–650 °C, hopping of proton, i.e. OH$^{\\bullet}$ ions occurs.

  9. Oxygen octahedral rotation mapping in calcium titanate/strontium titanate superlattices by transmission electron microscopy

    Science.gov (United States)

    Stone, Greg; Ciston, Jim; Haislmaier, Ryan; Vanleeuwen, Brian; Alem, Nasim; Schlom, Darrell; Gopalan, Venkatraman

    2014-03-01

    We report the investigation of oxygen octahedral rotation mapping in calcium titanate/barium titanate superlattices epitaxially grown on LSAT (001) with transmission electron microscopy. Analysis of the images shows induced antiphase rotations of the oxygen octahedral the strontium titanate layers that is absent in the bulk material at room temperature. These rotations play a key role in breaking the centrosymmetry of the material leading to polar properties as seen by second harmonic generation. We also map the local position of the cations to provide a complete picture of any relative local displacements and the oxygen-cation-oxygen bond angles.

  10. Controlled synthesis and structure tunability of photocatalytically active mesoporous metal-based stannate nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Caihong [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Chen, Haiyan [Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794 (United States); Ren, Zheng [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Dardona, Sameh; Piech, Martin [Department of Physical Sciences, United Technologies Research Center, East Hartford, CT 06108 (United States); Gao, Haiyong [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Gao, Pu-Xian, E-mail: puxian.gao@ims.uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States)

    2014-03-01

    Highlights: • A generic process has been developed for fabricating metal stannate nanostructures by simple substitution solution reactions followed by post-thermal treatments. • Band energy alignment, high carrier mobility and large specific surface area are found to play key roles for the enabled high efficiency in stannate nanostructured photocatalysts. • The developed process can be easily extended to the fabrication of other complex metal oxide nanostructures. - Abstract: A variety of stannate nanostructures have been fabricated for UV photocatalysis, including zinc- and cadmium-based stannates. As the template nanostructures, high surface-area mesoporous metal hydroxystannate [ZnSn(OH){sub 6} and CdSn(OH){sub 6}] nanoparticles (>100 m{sup 2}/g) have been synthesized using a simple, low-temperature substitution chemical process with controlled porosity, morphology and crystallinity. Post-synthetic thermal treatments were employed to obtain amorphous ZnSnO{sub 3}, CdSnO{sub 3}, ilmenite CdSnO{sub 3}, and crystalline Zn{sub 2}SnO{sub 4}–SnO{sub 2} nanoparticles. As a result, the band gaps can be tuned from 5.4 eV to 3.3 eV and from 4.9 eV to 2.1 eV for Zn-based and Cd-based stannates, respectively. Amorphous ZnSnO{sub 3} porous nanoparticles showed highest activity toward dye degradation under UV illumination followed by the Zn{sub 2}SnO{sub 4}-SnO{sub 2} and ilmenite CdSnO{sub 3} nanostructures due to their beneficial band structure alignment, high conductivities, and high specific surface areas. This study may provide an important strategy for high throughput synthesis and screening of functional complex metal oxide nanomaterials, while the enabled stannate nanomaterials could be utilized in various applications.

  11. Time-resolved X-ray absorption spectroscopy for the study of solid state reactions: synthesis of nanocrystalline barium titanate and thermal decomposition of ammonium hexachlorometallate compounds; Zeitaufgeloeste Roentgenabsorptionspektroskopie zur Untersuchung von Festkoerperreaktionen: Synthese von nanokristallinem Bariumtitanat und thermische Zersetzung von Ammoniumhexachlorometallat-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Rumpf, H.

    2001-07-01

    This report presents investigations on the mechanism of two different types of solid-state reactions: At first, barium titanate nanopowders were prepared through a combined polymerization and pyrolysis of a metallo-organic precursor. The mean particle size d{sub m} could be adjusted by choosing appropriate reaction temperatures and tempering atmospheres. In the present in situ study of this particular solid-phase reaction, X-ray absorption near edge structure (XANES) spectroscopy at the Ti K and Ba L{sub 3}-edges was applied in the preparation route of BaTiO{sub 3} nanopowders. A pronounced distortion of the lattice symmetry was found to occur in very fine BaTiO{sub 3} nanopowders (d{sub m} < 20 nm). Secondly, in situ XANES investigations were carried out at the Cl K, Pd L{sub 3}, Rh L{sub 3}, and Pt L{sub 3}-edges to study the mechanism of the thermal decomposition of ammonium hexachlorometallates. The results exceed structural information obtained by in situ X-ray diffraction methods and thermal analysis. Feff8 multiple scattering simulations have been carried out to disclose new intermediate phases of unknown reference compounds. (orig.)

  12. Radioisotope analyzer of barium

    International Nuclear Information System (INIS)

    Principle of operation and construction of radioisotope barium sulphate analyzer type MZB-2 for fast determination of barium sulphate content in barite ores and enrichment products are described. The gauge equipped with Am-241 and a scintillation detector enables measurement of barium sulphate content in prepared samples of barite ores in the range 60% - 100% with the accuracy of 1%. The gauge is used in laboratories of barite mine and ore processing plant. 2 refs., 2 figs., 1 tab. (author)

  13. Lower GI Series (Barium Enema)

    Science.gov (United States)

    ... barium into a bedpan or nearby toilet. A health care professional may give you an enema to flush out the rest of the barium. An x-ray technician and a radiologist perform a lower gastrointestinal (GI) series at a ...

  14. New barium tantalum sulphides

    International Nuclear Information System (INIS)

    The authors discuss a new barium tantalum sulphide, Ba3Ta2S8, prepared by sulphurization of a mixture of BaCO3 and Ta2O5. The electron and powder X-ray diffraction patterns of the compound are indexed on the basis of a monoclinic cell with lattice constants. A structure model is proposed. The refinement based on the powder X-ray diffraction intensities is performed

  15. Titan Aerial Daughtercraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Saturn's giant moon Titan has become one of the most fascinating bodies in the Solar System. Titan is the richest laboratory in the solar system for studying...

  16. Titan Haze

    Science.gov (United States)

    Anderson, Carrie M.; West, Robert; Lavvas, Panayotis

    2011-01-01

    The Titan haze exerts a dominating influence on surface visibility and atmospheric radiative heating at optical and near-infrared wavelengths and our desire to understand surface composition and atmospheric dynamics provides a strong motivation to study the properties of the haze. Prior to the Cassini/Huygens missions the haze was known to be global in extent, with a hemispheric contrast asymmetry, with a complicated structure in the polar vortex region poleward of about 55 deg latitude, and with a distinct layer near 370 km altitude outside of the polar vortex at the time of the Voyager 2 flyby. The haze particles measured by the Pioneer and Voyager spacecraft were both highly polarizing and strongly forward scattering, a combination that seems to require an aggregation of small (several tens of nm radius) primary particles. These same properties were seen in the Cassini orbiter and Huygens Probe data. The most extensive set of optical measurements were made inside the atmosphere by the Descent Imager/Spectral Radiometer (DISR) instrument on the Huygens Probe. At the probe location as determined by the DISR measurements the average haze particle contained about 3000 primary particles whose radius is about 40 nm. Three distinct vertical regions were seen in the DISR data with differing particle properties. Refractive indices of the particles in the main haze layer resemble those reported by Khare et al. between O.3S and about 0.7 micron but are more absorbing than the Khare et al. results between 0.7 micron and the long-wavelength limit of the DISR spectra at 1.6 micron. These and other results are described by Tomasko et al., and a broader summary of results was given by Tomasko and West,. New data continue to stream in from the Cassini spacecraft. New data analyses and new laboratory and model results continue to move the field forward. Titan's 'detached' haze layer suffered a dramatic drop in altitude near equinox in 2009 with implications for the circulation

  17. Synthesis and characterisation of Stannate ceramics for application as high performance material; Synthese und Charakterisierung von Stannat-Keramiken fuer die Verwendung als Hochleistungswerkstoff

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, A.

    2003-07-01

    New optimised wet-chemical routes (precipitation, polymerisation and sol-gel) for the production of pure, homogenic and nanocrystalline perovskitic earth alkali stannate powders (Ba- and SrSnO{sub 3}) were investigated. One of the routes was used to synthesise substituted partly new stannate ceramics (Ba{sub 2}YSnO{sub 5.5}, Ba{sub 2}NdSnO{sub 5.5} and nonstoichiometric compositions). The characterisation includes thermal analysis, Fourier transform infrared spectroscopy, x-ray diffraction and quantitative phase analysis. Further, results of impedance spectroscopy on the substituted powders are discussed. Thermal analysis data provide information about the precursor i. e. phase transition, ordering onset and mass changes. FTIR spectroscopy is both used to identify functional groups in the precursor and to compare with starting reagents as well as to investigate the surface behaviour of the calcined powders, i. e. adsorption of CO{sub 2} or water. X-ray diffraction data are used to compare the products in terms of phase purity and identification of additional phases as well as determination of crystallite size and distribution, structural parameters and quantitative phase analysis (target product and additional phases). The synthesis routes are compared and evaluated. The polymerisation and sol-gel-routes provide the best products in terms of material specific parameters. Different impedance spectra of Ba{sub 2}YSnO{sub 5.5}, Ba{sub 2}NdSnO{sub 5.5} and ''nonstoichiometric'' ceramics measured between RT and ca. 600 C are presented and calculated values for the specific conductance are shown. Ba{sub 2}YSnO{sub 5.5} can be applied as good conductive compound, Ba{sub 2}NdSnO{sub 5.5} and nonstoichiometric compositions as possible candidates for a membrane in a SOFC or as sensor material. (orig.)

  18. The Climate of Titan

    Science.gov (United States)

    Mitchell, Jonathan L.; Lora, Juan M.

    2016-06-01

    Over the past decade, the Cassini-Huygens mission to the Saturn system has revolutionized our understanding of Titan and its climate. Veiled in a thick organic haze, Titan's visible appearance belies an active, seasonal weather cycle operating in the lower atmosphere. Here we review the climate of Titan, as gleaned from observations and models. Titan's cold surface temperatures (˜90 K) allow methane to form clouds and precipitation analogously to Earth's hydrologic cycle. Because of Titan's slow rotation and small size, its atmospheric circulation falls into a regime resembling Earth's tropics, with weak horizontal temperature gradients. A general overview of how Titan's atmosphere responds to seasonal forcing is provided by estimating a number of climate-related timescales. Titan lacks a global ocean, but methane is cold-trapped at the poles in large seas, and models indicate that weak baroclinic storms form at the boundary of Titan's wet and dry regions. Titan's saturated troposphere is a substantial reservoir of methane, supplied by deep convection from the summer poles. A significant seasonal cycle, first revealed by observations of clouds, causes Titan's convergence zone to migrate deep into the summer hemispheres, but its connection to polar convection remains undetermined. Models suggest that downwelling of air at the winter pole communicates upper-level radiative cooling, reducing the stability of the middle troposphere and priming the atmosphere for spring and summer storms when sunlight returns to Titan's lakes. Despite great gains in our understanding of Titan, many challenges remain. The greatest mystery is how Titan is able to retain an abundance of atmospheric methane with only limited surface liquids, while methane is being irreversibly destroyed by photochemistry. A related mystery is how Titan is able to hide all the ethane that is produced in this process. Future studies will need to consider the interactions between Titan's atmosphere, surface

  19. Barium titanate core – gold shell nanoparticles for hyperthermia treatments

    OpenAIRE

    FarrokhTakin E; Ciofani G; Puleo GL; de Vito G; Filippeschi C; Mazzolai B; Piazza V; Mattoli V

    2013-01-01

    Elmira FarrokhTakin,1,2 Gianni Ciofani,1 Gian Luigi Puleo,1 Giuseppe de Vito,3,4 Carlo Filippeschi,1 Barbara Mazzolai,1 Vincenzo Piazza,3 Virgilio Mattoli1 1Center for Micro-BioRobotics @SSSA, Fondazione Istituto Italiano di Tecnologia, Pontedera, Pisa, Italy; 2The Biorobotics Institute, Scuola Superiore Sant'Anna, Pontedera, Pisa, Italy; 3Center for Nanotechnology Innovation @NEST, Fondazione Istituto Italiano di Tecnologia, Pisa, Italy; 4NEST, Scuola Normale Superiore, Pisa, Italy ...

  20. A modified method for barium titanate nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ashiri, R., E-mail: ro_ashiri@iaud.ac.ir [Department of Materials Science and Engineering, Dezful Branch, Islamic Azad University, P.O. Box 313, Dezful (Iran, Islamic Republic of); Nemati, Ali [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of); Sasani Ghamsari, M. [Solid State Lasers Research Group, Laser and Optics Research School, NSTRI, P.O. Box 11365-8486, Tehran (Iran, Islamic Republic of); Sanjabi, S. [Nanomaterials Group, Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Aalipour, M. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)

    2011-12-15

    Graphical abstract: TEM micrograph of BaTiO{sub 3} powders synthesized at 800 Degree-Sign C for 1 h and SAED pattern (inset) of BaTiO{sub 3} powders. In this research, a modified, cost efficient and quick sol-gel procedure was used for preparation of BaTiO{sub 3} nanoparticles. Highlights: Black-Right-Pointing-Pointer A modified process was used for preparation. Black-Right-Pointing-Pointer The modified process led to preparation of finer BaTiO{sub 3} nanoparticles in shorter period of time and lower temperature contrary to previous researches. Black-Right-Pointing-Pointer The proposed procedure seems to be more preferable for mass production. -- Abstract: In this research, a modified, cost effective sol-gel procedure applied to synthesize BaTiO{sub 3} nanoparticles. XRD and electron microscopy (SEM and TEM) applied for microstructural characterization of powders. The obtained results showed that the type of precursors, their ratio and the hydrolysis conditions had a great effect on time, temperature and therefore the costs of the synthesis process. By selection, utilization of optimized precursor's type, hydrolysis conditions, fine cubic BaTiO{sub 3} nanoparticles were synthesized at low temperature and in short time span (1 h calcination at 800 Degree-Sign C). The proposed procedure seems to be more preferable for mass production. The result indicated that the polymorphic transformation to tetragonal (ferroelectric characteristic) occurred at 900 Degree-Sign C, which might be an indication of being nanosized.

  1. Microstructure tuning and magnetism switching of ferroelectric barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Wenliang [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Deng, Hongmei [Instrumental Analysis and Research Center, Institute of Materials, Shanghai University, 99 Shangda Road, Shanghai 200444 (China); Ding, Nuofan; Yu, Lu [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Yue, Fangyu, E-mail: fyyue@ee.ecnu.edu.cn [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Yang, Pingxiong, E-mail: pxyang@ee.ecnu.edu.cn [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Chu, Junhao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2015-09-15

    Single-crystal and polycrystal BaTiO{sub 3} (BTO) materials synthesized by the physical and chemical methods, respectively, have been studied based on microstructural characterizations and magnetic measurements. The results of X-ray diffraction and Raman scatting spectra show that a single crystal tetragonal to polycrystalline pseudo-cubic structure transformation occurs in BTO ferroelectrics, dependent of growth conditions and interface effects. High-resolution transmission electron microscope data indicate that the as-prepared BTO/SrTiO{sub 3} (001) and BTO/SrRuO{sub 3}/SrTiO{sub 3} (001) heterostructures are highly c-axis oriented with atomic sharp interfaces. Lattice defects (i.e., edge-type misfit dislocations and stacking faults) in the heterostructures could be identified clearly and showed tunable with the variations of interface strain. Furthermore, the effects of vacancy defects on magnetic properties of BTO are discussed, which shows a diamagnetism–ferromagnetism switching as intrinsic vacancies increase. This work opens up a possible avenue to prepare magnetic BTO ferroelectrics. - Highlights: • Structure of BTO is tunable, depending on growth conditions and interface strain. • STEM–EDX data indicate the presence of lattice defects in BTO ferroelectrics. • BTO magnetism could be controlled by defects showing dia-ferromagnetism switching. • BTO with more vacancies shows RTFM, as evidence of vacancy magnetism effects.

  2. On Barium Oxide Solubility in Barium-Containing Chloride Melts

    Science.gov (United States)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V.

    2016-08-01

    Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl2-NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl2-MCl systems.

  3. Effect of La substitution on phase transitions in lead zirconate stannate titanate (55/35/10) ceramics

    International Nuclear Information System (INIS)

    Investigations of the structure-property relationships in Pb1-3x/2Lax(Zr0.55Sn0.35Ti0.10)O3. (PLZST 100x/55/35/10) have been performed for x between 0 and 0.08 by means of x-ray diffraction, electron microscopy, polarization, and dielectric studies. Factors affecting the phase stability were determined. The base composition PLZST 0/55/35/10 was ferroelectric (FE) at room temperature and transformed into an incommensurate antiferroelectric (AFEin) state on heating. Evidence was presented that low La addition could destabilize the FE state and PLZST 2/55/35/10 became AFEin at room temperature, which transformed to a multicell cubic state and then to a paraelectric (PE) phase upon heating. Further increase of La content enhanced the stability of the AFEin state at room temperature. Moreover, addition of La could also broaden the AFEin-PE phase transition temperature region and decrease its maximal dielectric constant εmax'

  4. Effect of A-site La3+ modified on dielectric and energy storage properties in lead zironate stannate titanate ceramics

    International Nuclear Information System (INIS)

    (Pb1-1.5xLax)(Zr0.66Sn0.23Ti0.11)O3 (PLZST) ceramics with different lanthanum (La3+) content (x = 0–6%) were prepared by conventional solid state reaction process, and exhibited excellent electrical properties with high switching field from AFE to FE phase and electric breakdown strength. The maximum dielectric constant (εm) and its corresponding temperature (Tm) decreased with La3+ doping and a phase transition from rhombohedral ferroelectric (FE) to tetragonal antiferroelectric (AFE) state was found at 2% La3+ doping. At room temperature, a maximum energy density of 1.47 J cm−3 was obtained for x = 4%. In addition, electric-field-dependent energy storage properties of PLZST (x = 4%) ceramics have been investigated, which could be ascribed to the AFE–FE phase transition associated with the increase of strain. (paper)

  5. MR Colonography with fecal tagging: Barium vs. barium ferumoxsil

    DEFF Research Database (Denmark)

    Achiam, M.P.; Chabanova, E.; Logager, V.B.;

    2008-01-01

    and Methods. Twenty patients referred to CC underwent dark lumen MRC prior to the colonoscopy. Two groups of patients received two different oral contrast agents (barium sulfate and barium sulfate/ferumoxsil) as a laxative-free fecal tagging prior to the MRC. After MRC, the contrast agent was rated...... qualitatively (with the standard method using contrast-to-wall ratio) and subjectively (using a visual analog scale [VAS]) by three different blinded observers. Results. Evaluated both qualitatively and subjectively, the tagging efficiency of barium sulfate/ferumoxsil was significantly better (P ... barium sulfate alone. The VAS method for evaluating the tagging efficiency of contrast agents showed a high correlation (observer 11, r = 0.91) to the standard method using contrast-to-wall ratio and also a high interclass correlation (observer 11 and III = 0.89/0.85). MRC found I of 22 (5%) polyps

  6. New barium tantalum sulphides

    International Nuclear Information System (INIS)

    A new barium tantalum sulphide has been synthesized by the reaction of CS2 with a mixture of BaCO3 and Ta2O5. The chemical analysis of the compound was performed for 3 components (Ba, Ta and S), and the chemical composition was found to be BaTa2S5. The powder X-ray diffraction peaks were indexable on the basis of a hexagonal cell with lattices constants of a=3.32A, c=25.13A. However, the electron diffraction measurements show that the structure is more complex than that observed by powder X-ray diffraction. The compound indicates metallic behavior and Pauli paramagnetism

  7. Future Titan Missions

    Science.gov (United States)

    Waite, J. H.; Coustenis, A.; Lorenz, R.; Lunine, J.; Stofan, E.

    2012-04-01

    New discoveries about Titan from the Cassini-Huygens mission have led to a broad range of mission class studies for future missions, ranging from NASA Discovery class to International Flagship class. Three consistent science themes emerge and serve as a framework for discussing the various mission concepts: Goal A: Explore Titan, an Earth-Like System - How does Titan function as a system? How are the similarities and differences with Earth, and other solar system bodies, a result of the interplay of the geology, hydrology, meteorology, and aeronomy present in the Titan system?; Goal B: Examine Titan’s Organic Inventory—A Path to Prebiological Molecules - What is the complexity of Titan’s organic chemistry in the atmosphere, within its lakes, on its surface, and in its putative subsurface water ocean and how does this inventory differ from known abiotic organic material in meteorites and therefore contribute to our understanding of the origin of life in the Solar System?; and Goal C: Explore Enceladus and Saturn’s magnetosphere—clues to Titan’s origin and evolution - What is the exchange of energy and material with the Saturn magnetosphere and solar wind? What is the source of geysers on Enceladus? Does complex chemistry occur in the geyser source? Within this scientific framework the presentation will overview the Titan Explorer, Titan AND Enceladus Mission, Titan Saturn System Mission, Titan Mare Explorer, and Titan Submersible. Future timelines and plans will be discussed.

  8. Abundance analysis of barium and mild barium stars

    CERN Document Server

    Smiljanic, R; Silva, L

    2007-01-01

    High signal to noise, high resolution spectra were obtained for a sample of normal, mild barium, and barium giants. Atmospheric parameters were determined from the FeI and FeII lines. Abundances for Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, and Gd, were determined from equivalent widths and model atmospheres in a differential analysis, with the red giant Eps Vir as the standard star. The different levels of s-process overabundances of barium and mild barium stars were earlier suggested to be related to the stellar metallicity. Contrary to this suggestion, we found in this work no evidence for barium and mild barium to have a different range in metallicity. However, comparing the ratio of abundances of heavy to light s-process elements, we found some evidence that they do not share the same neutron exposure parameter. The exact mechanism controlling this difference is still not clear. As a by-product of this analysis we identify two normal red giants misclass...

  9. Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

    KAUST Repository

    Deng, Rui

    2013-07-17

    Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn2+ and substituted for Zn (Mn Zn) in ZTO:Mn. This conclusion was supported by first-principles calculations. MnZn in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (MnSn). The nearest neighbor MnZn in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results. © 2013 AIP Publishing LLC.

  10. Discovery of the Barium Isotopes

    OpenAIRE

    SHORE, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; Thoennessen, M

    2009-01-01

    Thirty-eight barium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  11. Enhanced dielectric properties from barium strontium titanate films with strontium titanate buffer layers

    Science.gov (United States)

    Cole, M. W.; Ngo, E.; Hubbard, C.; Hirsch, S. G.; Ivill, M.; Sarney, W. L.; Zhang, J.; Alpay, S. P.

    2013-10-01

    In order to enhance the permittivity and tunability of the dielectric component, a thin film dielectric composite consisting of a radio frequency sputtered SrTiO3 (STO) buffer layer and metalorganic solution deposited Mg-doped BaxSr1-xTiO3 (Mg-BST) thin film overgrowth was developed using affordable industry standard processes and materials. The effect of the STO buffer layer thickness on the dielectric response of the heterostructure was investigated. Our results demonstrate that the composite film heterostructure, evaluated in the metal-insulator-metal configuration Pt/STO/Mg-BST/Pt on sapphire substrate, with the thinner (9-17 nm) STO buffer layers possessed enhanced permittivity (ɛr ˜ 491) with respect to the thicker 41 nm buffer layer (ɛr ˜ 360) and that of a control Mg-BST film without a STO buffer layer (ɛr ˜ 380). Additionally, the composite film with the thinner buffer layers were shown to have low losses (tan δ ˜ 0.02), low leakage characteristics (J = 7.0 × 10-9 A/cm2), high breakdown voltage (VBR > 10 V), a large grain microstructure (˜125 nm), and smooth pin-hole free surfaces. The enhanced permittivity of the composite dielectric film resulted from three major factors: (i) the template-effect of the thin STO buffer layer on the thicker Mg-BST over-layer film to achieve a large grain microstructure, (ii) the low viscosity of the metallo-organic solution deposition (MOSD) solution, which ensured heterogeneous nucleation of the Mg-BST overgrowth film on the surface of the STO buffer layer, and (iii) minimization of the low permittivity grain boundary phase (TiO2-x phase). The dielectric response of the BST can be explained using a thermodynamic model taking into account interlayer electrostatic and electromechanical interactions. Additionally, Mg doping of the BST enabled low loss and low leakage characteristics of the heterostructure. The large permittivity, low loss, low leakage characteristics, and defect free surfaces of the composite dielectric heterostructure promote tunable device miniaturization and hold the potential to enable enhanced electromagnetic coupling in ferromagnetic/high permittivity dielectric heterostructures, which in turn would facilitate the realization of integrated charge mediated voltage controlled magnetic radio frequency/microwave communication devices.

  12. Barium light source method and apparatus

    Science.gov (United States)

    Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

    2002-01-01

    Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

  13. Synthesis of BaTiO3 powder from barium titanyl oxalate (BTO) precursor employing microwave heating technique

    Indian Academy of Sciences (India)

    Y S Malghe; A V Gurjar; S R Dharwadkar

    2004-06-01

    Cubic barium titanate (BaTiO3) powder was synthesized by heating barium titanyl oxalate hydrate, BaTiO(C2O4)$_{2}\\cdot$4H2O (BTO) precursor in microwave heating system in air at 500°C. Heating BTO in microwave above 600°C yielded tetragonal form of BaTiO3. Experiments repeated in silicon carbide furnace showed that BaTiO3 was formed only above 700°C. The product obtained was cubic.

  14. Étude cinétique d'une voie de synthèse du titanate de baryum à partir de réactants (nitrate de baryum et dioxyde de titane) à l'état solide

    OpenAIRE

    Valdivieso, Françoise; Pijolat, Michèle; Soustelle, Michel

    1997-01-01

    National audience; The aim of this work is to study the solid state synthesis of barium titanate, from barium nitrate and titanium dioxide. L'objet de ce travail est l'étude d'une voie de synthèse du titanate de baryum à partir de nitrate de baryum et de dioxyde de titane à l'état solide. Une première étape a consisté à identifier les chemins réactionnels, c'est à dire, les produits intermédiaires qui peuvent se former au cours de la réaction, par une étude thermodynamique et expérimentale du...

  15. Titan's organic chemistry

    Science.gov (United States)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1985-01-01

    Voyager discovered nine simple organic molecules in the atmosphere of Titan. Complex organic solids, called tholins, produced by irradiation of the simulated Titanian atmosphere, are consistent with measured properties of Titan from ultraviolet to microwave frequencies and are the likely main constituents of the observed red aerosols. The tholins contain many of the organic building blocks central to life on earth. At least 100-m, and possibly kms thicknesses of complex organics have been produced on Titan during the age of the solar system, and may exist today as submarine deposits beneath an extensive ocean of simple hydrocarbons.

  16. Titans of Service

    OpenAIRE

    Lindberg-Repo, Kirsti Helena; Dube, Apramey

    2014-01-01

    TITANS OF SERVICE combines theory with practical insights, examples and references from experts. Bringing together 14 service experts, this book offers the most up-to-date knowledge from this field of academia in the U.S., Europe and Asia. In addition to offering theoretical insights, practical guidance and examples, this book also gives an overview of the current and future role of services. Titans of Service provides a framework for thinking about ways in which new knowledge on services is ...

  17. Is Titan Partially Differentiated?

    Science.gov (United States)

    Mitri, G.; Pappalardo, R. T.; Stevenson, D. J.

    2009-12-01

    The recent measurement of the gravity coefficients from the Radio Doppler data of the Cassini spacecraft has improved our knowledge of the interior structure of Titan (Rappaport et al. 2008 AGU, P21A-1343). The measured gravity field of Titan is dominated by near hydrostatic quadrupole components. We have used the measured gravitational coefficients, thermal models and the hydrostatic equilibrium theory to derive Titan's interior structure. The axial moment of inertia gives us an indication of the degree of the interior differentiation. The inferred axial moment of inertia, calculated using the quadrupole gravitational coefficients and the Radau-Darwin approximation, indicates that Titan is partially differentiated. If Titan is partially differentiated then the interior must avoid melting of the ice during its evolution. This suggests a relatively late formation of Titan to avoid the presence of short-lived radioisotopes (Al-26). This also suggests the onset of convection after accretion to efficiently remove the heat from the interior. The outer layer is likely composed mainly of water in solid phase. Thermal modeling indicates that water could be present also in liquid phase forming a subsurface ocean between an outer ice I shell and a high pressure ice layer. Acknowledgments: This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  18. Titan's surface and atmosphere

    Science.gov (United States)

    Hayes, Alexander G.; Soderblom, Jason M.; Ádámkovics, Máté

    2016-05-01

    Since its arrival in late 2004, the NASA/ESA Cassini-Huygens mission to Saturn has revealed Titan to be a world that is both strange and familiar. Titan is the only extraterrestrial body known to support standing bodies of stable liquid on its surface and, along with Earth and early Mars, is one of three places in the Solar System known to have had an active hydrologic cycle. With atmospheric pressures of 1.5 bar and temperatures of 90-95 K at the surface, methane and ethane condense out of Titan's nitrogen-dominated atmosphere and flow as liquids on the surface. Despite vast differences in environmental conditions and materials from Earth, Titan's methane-based hydrologic cycle drives climatic and geologic processes which generate landforms that are strikingly similar to their terrestrial counterparts, including vast equatorial dunes, well-organized channel networks that route material through erosional and depositional landscapes, and lakes and seas of liquid hydrocarbons. These similarities make Titan a natural laboratory for studying the processes that shape terrestrial landscapes and drive climates, probing extreme conditions impossible to recreate in earthbound laboratories. Titan's exotic environment ensures that even rudimentary measurements of atmospheric/surface interactions, such as wind-wave generation or aeolian dune development, provide valuable data to anchor physical models.

  19. Enhanced airglow at Titan

    Science.gov (United States)

    Royer, Emilie; Esposito, Larry; Wahlund, Jan-Erik

    2016-06-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) instrument made thousand of observations of Titan since its arrival in the Saturnian system in 2004, but only few of them have been analyzed yet. Using the imaging capability of UVIS combined to a big data analytics approach, we have been able to uncover an unexpected pattern in this observations: on several occasions the Titan airglow exhibits an enhanced brightness by approximately a factor of 2, generally combined with a lower altitude of the airglow emission peak. These events typically last from 10 to 30 minutes and are followed and preceded by an airglow of regular and expected level of brightness and altitude. Observations made by the Cassini Plasma Spectrometer (CAPS) instrument onboard Cassini allowed us to correlate the enhanced airglow observed on T-32 with an electron burst. The timing of the burst and the level of energetic electrons (1 keV) observed by CAPS correspond to a brighter and lower than typical airglow displayed on the UVIS data. Furthermore, during T-32 Titan was inside the Saturn's magnetosheath and thus more subject to bombardment by energetic particles. However, our analysis demonstrates that the presence of Titan inside the magnetosheath is not a necessary condition for the production of an enhanced airglow, as we detected other similar events while Titan was within Saturn's magnetosphere. The study presented here aims to a better understanding of the interactions of Titan's upper atmosphere with its direct environment.

  20. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures

  1. The TITAN reversed-field-pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures.

  2. Witnessing Springtime on Titan

    Science.gov (United States)

    Kohler, Susanna

    2016-02-01

    Have you ever wondered what springtime is like on Saturns largest moon, Titan? A team of researchers has analyzed a decade of data from the Cassini spacecraft to determine how Titans gradual progression through seasons has affected its temperatures.Observing the Saturn SystemThough Titan orbits Saturn once every ~16 days, it is Saturns ~30-year march around the Sun that sets Titans seasons: each traditional season on Titan spans roughly 7.5 years. Thus, when the Cassini spacecraft first arrived at Saturn in 2004 to study the giant planet and its ring system and moons, Titans northern hemisphere was in early winter. A decade later, the season in the northern hemisphere had advanced to late spring.A team scientists led by Donald Jennings (Goddard Space Flight Center) has now used data from the Composite Infrared Spectrometer (CIRS) on board Cassini to analyze the evolution of Titans surface temperature between 2004 and 2014.Changing of SeasonsSurface brightness temperatures (with errors) on Titan are shown in blue for five time periods between 2004 and 2014. The location of maximum temperature migrates from 19S to 16N over the decade. Two climate models are also shown in green (high thermal inertia) and red (low thermal inertia). [Jennings et al. 2016]CIRS uses the decreased opacity of Titans atmosphere at 19 m to detect infrared emission from Titans surface at this wavelength. From this data, Jennings and collaborators determine Titans surface temperature for five time intervals between 2004 and 2014. They bin the data into 10 latitude bins that span from the south pole (90S) to the north pole (90N).The authors find that the maximum temperature on the moon stays stable over the ten-year period at 94 K, or a chilly -240F). But as time passes, the latitude with the warmest temperature shifts from 19S to 16N, marking the transition from early winter to late spring. Over the decade of monitoring, the surface temperature near the south pole decreased by ~2 K, and that

  3. Band gap tuning and room temperature ferromagnetism in Co doped Zinc stannate nanostructures

    Science.gov (United States)

    Sumithra, S.; Victor Jaya, N.

    2016-07-01

    The effect of Co doping on structural, optical and magnetic behavior of pure and Co doped Zinc stannate (ZTO) nanostructures was investigated. Pure and Co (1%, 3% & 5%) doped Zn2SnO4 compounds were prepared through simple precipitation route. Formation of cubic inverse spinel structure and metal oxide vibrations of the samples were investigated using XRD and FTIR. Co doping influences the crystallite size producing micro strain in ZTO lattice. Poly dispersed rod like shape of the particles was examined by FESEM. Elemental composition of prepared samples was identified by EDAX analysis. Optical Absorption spectra shows significant red shift on increasing the dopant concentration which indicates the reduction in optical band gap. Visible luminescence observed from photoluminescence studies confirms the presence of oxygen vacancies and trap sites in the lattice. Magnetization analysis reveals the enhanced ferromagnetic behavior in all Co doped ZTO samples. The amplified ferromagnetic ordering in Co doped ZTO compounds has been explained in terms of defects serving as free spin polarized prophetic carriers.

  4. Humidity Sensor Based on PEDOT:PSS and Zinc Stannate Nano-composite

    Science.gov (United States)

    Aziz, Shahid; Chang, Dong Eui; Doh, Yang Hoi; Kang, Chul Ung; Choi, Kyung Hyun

    2015-10-01

    A composite of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and zinc stannate (ZnSnO3) has been introduced for impedance-based humidity sensing, owing to its high sensitivity, good stability, very fast response (˜0.2 s) and recovery time (˜0.2 s), small hysteresis, repeatability, low-cost fabrication and wide range of sensitivity. Both materials were mixed in three different weight percentage ratios, to optimize the performance of the sensors. Best response was observed for 5 wt.% PEDOT:PSS and 5 wt.% ZnSnO3. The impedance of the sensor was dropped immensely from 1.5 MΩ to 50 kΩ by changing relative humidity from 0% to 90%. The reason for this improvement in sensitivity was analyzed by virtue of sensing mechanisms and different characterizations (three dimensional (3D) nano-profiler, optical microscope, and fourier transform infra-red (FTIR) spectroscopy) revealing the surface morphology and chemical structure of the film. Due to its response and ability to sense human breath and skin humidity, it is suitable for environmental, artificial skin and food industry applications.

  5. Sensitization of Perovskite Strontium Stannate SrSnO3 towards Visible-Light Absorption by Doping

    Directory of Open Access Journals (Sweden)

    Hungru Chen

    2014-01-01

    Full Text Available Perovskite strontium stannate SrSnO3 is a promising photocatalyst. However, its band gap is too large for efficient solar energy conversion. In order to sensitize SrSnO3 toward visible-light activities, the effects of doping with various selected cations and anions are investigated by using hybrid density functional calculations. Results show that doping can result in dopant level to conduction band transitions which lie lower in energy compared to the original band gap transition. Therefore, it is expected that doping SrSnO3 can induce visible-light absorption.

  6. Preparation, crystal structure, spectra and energy levels of the trivalent ytterbium ion doped into rare earth stannates

    Science.gov (United States)

    Ning, Kaijie; Zhang, Qingli; Sun, Dunlu; Yin, Shaotang; Jiang, Haihe

    2012-01-01

    Yb3+-doped Rare Earth Stannates Ln2Sn2O7(Ln=Y, Gd) with space group Fd3m were synthesized by co-precipitation technique. Their structures were determined by Rietveld refinement to their X-ray diffraction, and their atom coordinates, lattice parameters and temperature factors were given. From emission, absorption and excitation spectra, the energy levels of Yb3+ in Ln2Sn2O7(Ln=Y, Gd) were assigned and the crystal field parameters were fitted to energy splitting of Yb3+-doped Ln2Sn2O7 (Ln=Y, Gd).

  7. Methane ocean on Titan?

    Science.gov (United States)

    Bell, Peter M.

    There was an impressive list of names on a recent scientific communication that argues for the existence on Titan of an ocean of liquid methane (CH4) perhaps several hundred meters deep. C. Sagan and S. Dermott with helpful comments by S. Oter, S. Ostro, S. Peale, C. Yoder, W. Thompson, S. Squyres, G. Pettengill, P. Gierasch, and B. Khare speculate that such a methanic ocean, with its Saturnian tides and its tholinian floor, should exist all over Titan's surface; it should unless, they conclude, there is the ‘distracting coincidence [that] … the position of the surface of Titan [is] … near the liquidus in the CH4phase diagram [and, consequently, there is] …almost no methane ocean at all’ (Nature, 300, 731, 1982).We know very little about Titan and its surface; the way of checking into Sagan and Dermott's ideas appears to rest on the interpretation of radar reflectivity data. Preliminary attempts to obtain radar data were made in 1979 with the 305-m Arecibo telescope, but only broad limits resulted. The next opportunity for a measurement at Arecibo comes in the 1990's. Of course, the ideal circumstance would be to send spacecraft equipped with a radar reflectometer for a Titan flyby.

  8. The effects of surface treatment and stannate as an electrolyte additive on the corrosion and electrochemical performances of pure aluminum in an alkaline methanol-water solution

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, X.X. [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou 310027, Zhejiang (China); Wang, J.M., E-mail: wjm@zju.edu.cn [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou 310027, Zhejiang (China); Wang, Q.L.; Kong, D.S.; Shao, H.B. [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou 310027, Zhejiang (China); Zhang, J.Q.; Cao, C.N. [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou 310027, Zhejiang (China); State Key Laboratory for Corrosion and Protection of Metal, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China)

    2010-06-01

    Pure aluminum electrodes were treated in alkaline stannate solutions, and the effects of some factors such as NaOH content and treating time were explored. The corrosion and electrochemical performances of the modified aluminum anodes in 4.0 M KOH methanol-water mixed solutions containing a methanol/water volume ratio of 7:3 (30% water) with and without stannate were investigated by means of hydrogen collection, polarization curve, galvanostatic discharge, scanning electron microscopy (SEM), and energy dispersive analysis of X-ray (EDAX). Metallic tin with high hydrogen evolution overpotential was deposited in aluminum surfaces by the modification treatments using stannate, resulting in the relatively low corrosion rate and markedly enhanced discharge performance of the modified aluminum anodes. In our experimental range the aluminum electrode treated in the solution with 0.1 M NaOH for 30 min showed lower corrosion rate and better discharge performance. The addition of Na{sub 2}SnO{sub 3} in 4.0 M KOH methanol-water mixed solutions with 30% water inhibited the corrosion of the aluminum electrodes modified in the treating solution with 0.1 M NaOH for 30 min, resulting from the deposition of tin with high hydrogen evolution overpotential in aluminum surfaces. The deposition of metallic tin on the electrode surface and the existence of stannate in the electrolytes were responsible for the notable enhancement in the discharge performance of the modified aluminum anode.

  9. Effects of neonatal exposure to the flame retardant tetrabromobisphenol-A, aluminum diethylphosphinate or zinc stannate on long-term potentiation and synaptic protein levels in mice

    NARCIS (Netherlands)

    Hendriks, Hester S; Koolen, Lucas A E; Dingemans, Milou M L; Viberg, Henrik; Lee, Iwa; Leonards, Pim E G; Ramakers, Geert M J; Westerink, Remco H S

    2015-01-01

    Brominated flame retardants such as tetrabromobisphenol-A (TBBPA) may exert (developmental) neurotoxic effects. However, data on (neuro)toxicity of halogen-free flame retardants (HFFRs) are scarce. Recent in vitro studies indicated a high neurotoxic potential for some HFFRs, e.g., zinc stannate (ZS)

  10. Effects of neonatal exposure to the flame retardant tetrabromobisphenol-A, aluminum diethylphosphinate or zinc stannate on long-term potentiation and synaptic protein levels in mice

    NARCIS (Netherlands)

    Hendriks, Hester; Koolen, Lucas; Dingemans, Milou; Viberg, Henrik; Lee, Iwa; Leonards, P.E.G.; Ramakers, G.M.J.; Westerink, Remco

    2014-01-01

    Brominated flame retardants such as tetrabromobisphenol-A (TBBPA) may exert (developmental) neurotoxic effects. However, data on (neuro)toxicity of halogen-free flame retardants (HFFRs) are scarce. Recent in vitro studies indicated a high neurotoxic potential for some HFFRs, e.g., zinc stannate (ZS)

  11. The tides of Titan.

    Science.gov (United States)

    Iess, Luciano; Jacobson, Robert A; Ducci, Marco; Stevenson, David J; Lunine, Jonathan I; Armstrong, John W; Asmar, Sami W; Racioppa, Paolo; Rappaport, Nicole J; Tortora, Paolo

    2012-07-27

    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 ± 0.150 and k(2) = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.

  12. Models of Titan's Ionosphere

    Science.gov (United States)

    Robertson, I. P.; Cravens, T. E.; Waite, J. H.; Wahlund, J.; Yelle, R. V.; Vuitton, V.; Coates, A.; Magee, B.; Gell, D. A.

    2007-12-01

    During the TA and T18 encounters with Titan, in situ measurements were made of Titan's atmosphere and ionosphere by several instruments on board the Cassini Orbiter, including the Ion and Neutral Mass Spectrometer (INMS), the Langmuir probe on the Cassini Radio and Plasma Wave Experiment (RPWS), and the Cassini Plasma Spectrometer Subsystem (CAPS). Both of these encounters were on the day as well as the night side of Titan. The model uses neutral densities measured by the INMS instrument and the electron temperature was measured by the RPWS instrument. The model also includes energetic electron fluxes measured by the CAPS instrument, which act as an important source of ionization on the night side. The modeled ion densities are compared with densities measured by INMS in its Open Source mode.

  13. Impact craters on Titan

    Science.gov (United States)

    Wood, Charles A.; Lorenz, Ralph; Kirk, Randy; Lopes, Rosaly; Mitchell, Karl; Stofan, Ellen; ,

    2010-01-01

    Five certain impact craters and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain craters have morphologies similar to impact craters on rocky planets, as well as two with radar bright, jagged rims. The less certain craters often appear to be eroded versions of the certain ones. Titan's craters are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of craters implies that Titan's surface is quite young, but the modeled age depends on which published crater production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that craters with diameters smaller than about 35 km are younger than 200 million years old, and larger craters are older. Craters are not distributed uniformly; Xanadu has a crater density 2-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of craters on the leading hemisphere, and craters are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact craters, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact craters with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles.

  14. Diurnal variations of Titan

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  15. Radioisotope barium sulphate gauge MZB-2

    International Nuclear Information System (INIS)

    A method and the gauge for measuring content of barium sulphate are described. The gauge is intended for fast determination of barium sulphate in barite ore and in output products of the enrichment process. The measuring range 60-100% of BaSO4, accuracy ±1% and measuring time 60 s were reached. The barium sulphate gauge is used in barite mine ''Boguszow'' in Poland. (author)

  16. The problem of the barium stars

    Science.gov (United States)

    Bohm-Vitense, E.; Nemec, J.; Proffitt, C.

    1984-01-01

    Ultraviolet observations of barium stars and other cool stars with peculiar element abundances are reported. Those observations attempted to find hot white dwarf companions. Among six real barium stars studied, only Zeta Cap was found to have a white dwarf companion. Among seven mild, or marginal, barium stars studied, at least three were found to have hot subluminous companions. It is likely that all of them have white dwarf companions.

  17. Barium aspiration and alveolarisation of barium in an infant: A case report and review of management

    Directory of Open Access Journals (Sweden)

    Alan F. Isles

    2014-05-01

    Full Text Available We describe a case of bilateral inhalation and alveolarisation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-oesophageal cleft. We review the literature on barium aspiration, its consequences and make recommendations for management.

  18. ONE CASE REPORT OF ACUTE POISONING BY BARIUM CARBONATE

    Institute of Scientific and Technical Information of China (English)

    GE Qin-min; BIAN Fan; WANG Shu-yun; SHEN Sheng-hui

    2009-01-01

    @@ Most barium poisoning cases were caused by oral intake by mistake. Recent years, barium carbonate poisoning has been rare to be reported. Here we reported a case of acute barium carbonate toxication taken orally on purpose.

  19. Titanic Weather Forecasting

    Science.gov (United States)

    2004-04-01

    New Detailed VLT Images of Saturn's Largest Moon Optimizing space missions Titan, the largest moon of Saturn was discovered by Dutch astronomer Christian Huygens in 1655 and certainly deserves its name. With a diameter of no less than 5,150 km, it is larger than Mercury and twice as large as Pluto. It is unique in having a hazy atmosphere of nitrogen, methane and oily hydrocarbons. Although it was explored in some detail by the NASA Voyager missions, many aspects of the atmosphere and surface still remain unknown. Thus, the existence of seasonal or diurnal phenomena, the presence of clouds, the surface composition and topography are still under debate. There have even been speculations that some kind of primitive life (now possibly extinct) may be found on Titan. Titan is the main target of the NASA/ESA Cassini/Huygens mission, launched in 1997 and scheduled to arrive at Saturn on July 1, 2004. The ESA Huygens probe is designed to enter the atmosphere of Titan, and to descend by parachute to the surface. Ground-based observations are essential to optimize the return of this space mission, because they will complement the information gained from space and add confidence to the interpretation of the data. Hence, the advent of the adaptive optics system NAOS-CONICA (NACO) [1] in combination with ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile now offers a unique opportunity to study the resolved disc of Titan with high sensitivity and increased spatial resolution. Adaptive Optics (AO) systems work by means of a computer-controlled deformable mirror that counteracts the image distortion induced by atmospheric turbulence. It is based on real-time optical corrections computed from image data obtained by a special camera at very high speed, many hundreds of times each second (see e.g. ESO Press Release 25/01 , ESO PR Photos 04a-c/02, ESO PR Photos 19a-c/02, ESO PR Photos 21a-c/02, ESO Press Release 17/02, and ESO Press Release 26/03 for earlier NACO

  20. Rare-earth barium stannates: Synthesis, characterization, and potential use as substrates for YBa2Cu3O7-δ superconductor

    International Nuclear Information System (INIS)

    A new group of complex perovskites, REBa2SnO5.5 (where RE = Pr, Sm, Eu, and Gd) have been synthesized and sintered as single-phase materials with high sintered density and stability by the solid-state reaction method. The structure of REBa2SnO5.5 was studied by the X-ray diffraction technique, and all of them were found to be isostructural and have a cubic perovskite structure. The dielectric constant and loss factor values of these materials are in a range suitable for substrate applications. The X-ray diffraction and resistivity measurements have shown that there is no detectable reaction between YBa2Cu3O7-δ and REBa2SnO5.5, even when the substances are mixed thoroughly and sintered at 950 C for 15 h. Thick films of YBa2Cu3O7-δ fabricated on polycrystalline REBa2SnO5.5 substrates gave superconducting zero resistivity transition TC(0) = 92 K, indicating the suitability of these new materials as substrates for YBa2Cu3O7-δ films

  1. Laser cooling and trapping of barium

    NARCIS (Netherlands)

    De, Subhadeep

    2008-01-01

    Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers a

  2. Titan's global geologic processes

    Science.gov (United States)

    Malaska, Michael; Lopes, Rosaly M. C.; Schoenfeld, Ashley; Birch, Samuel; Hayes, Alexander; Williams, David A.; Solomonidou, Anezina; Janssen, Michael A.; Le Gall, Alice; Soderblom, Jason M.; Neish, Catherine; Turtle, Elizabeth P.; Cassini RADAR Team

    2016-10-01

    We have mapped the Cassini SAR imaged areas of Saturn's moon Titan in order to determine the geological properties that modify the surface [1]. We used the SAR dataset for mapping, but incorporated data from radiometry, VIMS, ISS, and SARTopo for terrain unit determination. This work extends our analyses of the mid-latitude/equatorial Afekan Crater region [2] and in the southern and northern polar regions [3]. We placed Titan terrains into six broad terrain classes: craters, mountain/hummocky, labyrinth, plains, dunes, and lakes. We also extended the fluvial mapping done by Burr et al. [4], and defined areas as potential cryovolcanic features [5]. We found that hummocky/mountainous and labyrinth areas are the oldest units on Titan, and that lakes and dunes are among the youngest. Plains units are the largest unit in terms of surface area, followed by the dunes unit. Radiometry data suggest that most of Titan's surface is covered in high-emissivity materials, consistent with organic materials, with only minor exposures of low-emissivity materials that are consistent with water ice, primarily in the mountain and hummocky areas and crater rims and ejecta [6, 7]. From examination of terrain orientation, we find that landscape evolution in the mid-latitude and equatorial regions is driven by aeolian processes, while polar landscapes are shaped by fluvial, lacrustine, and possibly dissolution or volatilization processes involving cycling organic materials [3, 8]. Although important in deciphering Titan's terrain evolution, impact processes play a very minor role in the modification of Titan's landscape [9]. We find no evidence for large-scale aqueous cryovolcanic deposits.References: [1] Lopes, R.M.C. et al. (2010) Icarus, 205, 540–558. [2] Malaska, M.J. et al. (2016) Icarus, 270, 130–161. [3] Birch et al., in revision. [4] Burr et al. (2013) GSA Bulletin 125, 299–321. [5] Lopes et al. JGR: Planets, 118, 1–20. [6] Janssen et al., (2009) Icarus, 200, 222–239. [7

  3. Simulations of Titan's paleoclimate

    CERN Document Server

    Lora, Juan M; Russell, Joellen L; Hayes, Alexander G

    2014-01-01

    We investigate the effects of varying Saturn's orbit on the atmospheric circulation and surface methane distribution of Titan. Using a new general circulation model of Titan's atmosphere, we simulate its climate under four characteristic configurations of orbital parameters that correspond to snapshots over the past 42 kyr, capturing the amplitude range of long-period cyclic variations in eccentricity and longitude of perihelion. The model, which covers pressures from the surface to 0.5 mbar, reproduces the present-day temperature profile and tropospheric superrotation. In all four simulations, the atmosphere efficiently transports methane poleward, drying out the low- and mid-latitudes, indicating that these regions have been desert-like for at least tens of thousands of years. Though circulation patterns are not significantly different, the amount of surface methane that builds up over either pole strongly depends on the insolation distribution; in the present-day, methane builds up preferentially in the no...

  4. Titan's Eccentricity Tides

    Science.gov (United States)

    Iess, L.; Jacobson, R.; Ducci, M.; Stevenson, D. J.; Lunine, J. I.; Armstrong, J. W.; Asmar, S.; Racioppa, P.; Rappaport, N. J.; Tortora, P.

    2011-12-01

    The large eccentricity (e=0.03) of Titan's orbit causes significant variations in the tidal field from Saturn and induces periodic stresses in the satellite body at the orbital period (about 16 days). Peak-to-peak variations of the tidal field (from pericenter to apocenter) are about 18% (6e). If Titan hosts a liquid layer (such as an internal ocean), the gravity field would exhibit significant periodic variations. The response of the body to fast variations of the external, perturbing field is controlled by the Love numbers, defined for each spherical harmonic as the ratio between the perturbed and perturbing potential. For Titan the largest effect is by far on the quadrupole field, and the corresponding Love number is indicated by k2 (assumed to be identical for all degree 2 harmonics). Models of Titan's interior generally envisage a core made up of silicates, surrounded by a layer of high pressure ice, possibly a liquid water or water-ammonia ocean, and an ice-I outer shell, with variations associated with the dehydration state of the core or the presence of mixed rock-ice layers. Previous analysis of Titan's tidal response [1] shows that k2 depends crucially on the presence or absence of an internal ocean. k2 was found to vary from about 0.03 for a purely rocky interior to 0.48 for a rigid rocky core surrounded by an ocean and a thin (20 km) ice shell. A large k2 entails changes in the satellite's quadrupole coefficients by a few percent, enough to be detected by accurate range rate measurements of the Cassini spacecraft. So far, of the many Cassini's flybys of Titan, six were used for gravity measurements. During gravity flybys the spacecraft is tracked from the antennas of NASA's Deep Space Network using microwave links at X- and Ka-band frequencies. A state-of-the-art instrumentation enables range rate measurements accurate to 10-50 micron/s at integration times of 60 s. The first four flybys provided the static gravity field and the moment of inertia factor

  5. Organic chemistry on Titan

    Science.gov (United States)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1979-01-01

    Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

  6. Landscape Evolution of Titan

    Science.gov (United States)

    Moore, Jeffrey

    2012-01-01

    Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan's atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere. This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30 degrees of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High midlatitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover.

  7. Tris(cyclohexylammonium cis-dichloridobis(oxalato-κ2O1,O2stannate(IV chloride monohydrate

    Directory of Open Access Journals (Sweden)

    Modou Sarr

    2013-11-01

    Full Text Available The crystal structure of the title compound, (C6H14N3[Sn(C2O42Cl2]Cl·H2O, contains three cyclohexylammonium cations, one stannate(IV dianion, one isolated chloride anion and one lattice water molecule. The cyclohexylammonium cations adopt chair conformations. In the complex anion, two bidentate oxalate ligands and two chloride anions in cis positions coordinate octahedrally to the central SnIV atom. The cohesion of the molecular entities is ensured by the formation of N—H...O, O—H...O, O—H...Cl and N—H...Cl interactions involving cations, anions and the lattice water molecule, giving rise to a layer-like arrangement parallel to (010.

  8. Effect of annealing on the electrical, optical and structural properties of cadmium stannate thin films prepared by spray pyrolysis technique

    International Nuclear Information System (INIS)

    Polycrystalline thin films of cadmium stannate (Cd2SnO4) were deposited by spray pyrolysis method on the Corning substrates at substrate temperature of 525 oC. Further, the films were annealed at 600 oC in vacuum for 30 min. These films were characterized for their structural, electrical and optical properties. The experimental results showed that the post-deposition annealing in vacuum has a significant influence on the properties of the films. The average grain size of the film was increased from 27.3 to 35.0 nm on heat treatment. The average optical transmittance in the visible region (500-850 nm) is decreased from 81.4% to 73.4% after annealing in vacuum. The minimum resistivity achieved in the present study for the vacuum annealed films is the lowest among the reported values for the Cd2SnO4 thin films prepared by spray pyrolysis method.

  9. Synthesis of barium titanium oxide from barium sulphate and anatase. Study of equimolar mixtures under different atmospheres

    International Nuclear Information System (INIS)

    To enable the ceramization of a barium sulphate-rich radioactive waste the synthesis of barium titanium oxide is studied by using anatase and barium sulphate. As a function of the calcination atmosphere, helium (or air) and Ar/H2, two reactions are studied. A mechanism of barium titanium oxide synthesis in helium (or in air) is proposed

  10. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    In a prospective double blind study, acetylcysteine, a local and systemic respiratory tract mucolytic agent, or a placebo, were given to 100 patients prior to a double contrast barium meal to decrease the gastric mucus viscosity and to make the mucus layer thinner, in order to permit barium to outline the furrows surrounding the areae gastricae instead of the overlying thick mucus. However, acetylcysteine failed to improve either visualization of the areae gastricae or the general quality of the double contrast barium meal. (orig.)

  11. Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

  12. Acetylene on Titan

    Science.gov (United States)

    Singh, Sandeep; McCord, Thomas B.; Combe, Jean-Philippe; Rodriguez, Sebastien; Cornet, Thomas; Le Mouélic, Stéphane; Clark, Roger Nelson; Maltagliati, Luca; Chevrier, Vincent

    2016-10-01

    Saturn's moon Titan possesses a thick atmosphere that is mainly composed of N2 (98%), CH4 (2 % overall, but 4.9% close to the surface) and less than 1% of minor species, mostly hydrocarbons [1]. A dissociation of N2 and CH4 forms complex hydrocarbons in the atmsophere and acetylene (C2H2) and ethane (C2H6) are produced most abundently. Since years, C2H2 has been speculated to exist on the surface of Titan based on its high production rate in the stratosphere predicted by photochemical models [2,3] and from its detection as trace gas sublimated/evaporated from the surface after the landing of the Huygens probe by the Gas Chromatograph Mass Spectrometer (GCMS) [1]. Here we show evidence of acetylene (C2H2) on the surface of Titan by detecting absorption bands at 1.55 µm and 4.93 µm using Cassini Visual and Infrared Mapping Spectrometer (VIMS) [4] at equatorial areas of eastern Shangri-La, and Fensal-Aztlan/Quivira.An anti-correlation of absorption band strength with albedo indicates greater concentrations of C2H2 in the dark terrains, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.References:[1]Niemann et al., Nature 438, 779–784 (2005).[2]Lavvas et al., Planetary and Space Science 56, 67 – 99 (2008).[3]Lavvas et al., Planetary and Space Science 56, 27 – 66 (2008).[4] Brown et al., The Cassini-Huygens Mission 111–168 (Springer, 2004).

  13. The Tides of Titan

    Science.gov (United States)

    Iess, L.; Jacobson, R.; Ducci, M.; Stevenson, D. J.; Lunine, J. I.; Armstrong, J. W.; Asmar, S.; Racioppa, P.; Rappaport, N. J.; Tortora, P.

    2012-12-01

    Titan has long been thought to host a subsurface water ocean. A liquid water or water-ammonia layer underneath the outer icy shell was invoked to explain the Voyager and Cassini observations of abundant methane (an easily dissociated species) in the atmosphere of the satellite. Given the paucity of surface hydrocarbon reservoirs, the atmospheric methane must be supplied by the interior, and an ocean can both provide a large storage volume and facilitate the outgassing from the deeper layers of the satellite to the surface. Huygens probe observations of a Schumann-like resonance point to the presence of an electrically conductive layer at a depth of 50-100 km, which has been interpreted to be the top of an ammonia-doped ocean [1]. Cassini gravity observations provide stronger evidence of the existence of such subsurface ocean. By combining precise measurements of the spacecraft range rate during six flybys, suitably distributed along Titan's orbit (three near pericenter, two near apocenter one near quadrature), we have been able to determine the k2 Love number to be k2 = 0.589±0.150 and k2 = 0.637±0.224 in two independent so-lutions (quoted uncertainties are 2-sigma) [2]. Such a large value indicates that Titan is highly deformable over time scales of days, as one would expect if a global ocean were hidden beneath the outer icy shell. The inclusion of time-variable gravity in the solution provided also a more reliable estimate of the static field, including an updated long-wavelength geoid. We discuss the methods adopted in our solutions and some implications of our results for the interior structure of Titan, and outline the expected improvements from the additional gravity flybys before the end of mission in 2017. [1] C. Beghin, C. Sotin, M. Hamelin, Comptes Rendue Geoscience, 342, 425 (2010). [2] L. Iess, R.A. Jacobson, M. Ducci, D.J. Stevenson, J.I. Lunine, J.W. Armstrong, S.W. Asmar, P. Racioppa, N.J. Rappaport, P. Tortora, Science, 337, 457 (2012).

  14. Titan Airship Surveyor

    Science.gov (United States)

    Kerzhanovich, V.; Yavrouian, A.; Cutts, J.; Colozza, A.; Fairbrother, D.

    2001-01-01

    Saturn's moon Titan is considered to be one of the prime candidates for studying prebiotic materials - the substances that precede the formation of life but have disappeared from the Earth as a result of the evolution of life. A unique combination of a dense, predominantly nitrogen, atmosphere (more than four times that of the Earth), low gravity (six times less than on the Earth) and small temperature variations makes Titan the almost ideal planet for studies with lighter-than-air aerial platforms (aerobots). Moreover, since methane clouds and photochemical haze obscure the surface, low-altitude aerial platforms are the only practical means that can provide global mapping of the Titan surface at visible and infrared wavelengths. One major challenge in Titan exploration is the extremely cold atmosphere (approx. 90 K). However, current material technology the capability to operate aerobots at these very low temperatures. A second challenge is the remoteness from the Sun (10 AU) that makes the nuclear (radioisotopic) energy the only practical source of power. A third challenge is remoteness from the Earth (approx. 10 AU, two-way light-time approx. 160 min) which imposes restrictions on data rates and makes impractical any meaningful real-time control. A small-size airship (approx. 25 cu m) can carry a payload approximately 100 kg. A Stirling engine coupled to a radioisotope heat source would be the prime choice for producing both mechanical and electrical power for sensing, control, and communications. The cold atmospheric temperature makes Stirling machines especially effective. With the radioisotope power source the airship may fly with speed approximately 5 m/s for a year or more providing an excellent platform for in situ atmosphere measurements and a high-resolution remote sensing with unlimited access on a global scale. In a station-keeping mode the airship can be used for in situ studies on the surface by winching down an instrument package. Floating above the

  15. Neutral Barium Cloud Evolution at Different Altitudes

    Institute of Scientific and Technical Information of China (English)

    李磊; 徐荣栏

    2002-01-01

    Considering the joint effects of diffusion, collision, oxidation and photoionization, we study the evolution of the barium cloud at different altitudes in the space plasma active experiment. The results present the variation of the loss rate, number density distribution and brightness of the barium cloud over the range from 120 to 260km.This can be divided into oxidation, oxidation plus photoionization and photoionization regions.

  16. Small barium rail gun for plasma injection.

    Science.gov (United States)

    Kiwamoto, Y

    1980-03-01

    A small rail gun with a barium electrode can be operated at higher than one shot per second to produce more than 2x10(16) barium ions with energy 10-20 eV. The operation of the gun takes advantage of the external magnetic field for cross-field plasma injection into a trap. Up to 7 kG of the magnetic field examined, the gun performance improves with the increased magnetic field strength.

  17. Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Luptáková Alena

    2015-12-01

    Full Text Available Acid mine drainage (AMD is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. The barium salts application presents one of the methods for the sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the sulphates precipitation in the form of barium sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by sulphate-reducing bacteria. Applied BaSO4 came from experiments of sulphates removal from Smolnik AMD using BaCl2.

  18. Venous barium embolization, a rare, potentially fatal complication of barium enema: 2 case reports

    International Nuclear Information System (INIS)

    Venous embolization of barium has been recognized for 4 decades as one of the most dreaded complications of barium enema. Fortunately, the condition is extremely rare. In this report, the radiographic findings in 2 cases of venous embolization (one involving the portal vein and one systematic) are described, and ways to decrease the risk of this complication are discussed. (author)

  19. Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water

    Science.gov (United States)

    Ota, K.; Conger, W. L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

  20. Synthesis of barium mercaptides and application of antimony/barium mercaptides

    Institute of Scientific and Technical Information of China (English)

    瞿龙; 张露露; 舒万艮

    2001-01-01

    Mercaptoacetic acid, isooctyl thioglycolate and barium hydroxide used as start materials, barium bis (2-ethylhexyl thioglycolate) (Ba(2EHTG)2), barium thioglycolate (Ba(TG)) and barium bisthioglycolate (Ba(TG)2) were synthesized. Their optimum synthetic techniques were discussed, and some physicochemical data were reported. Infrared spectroscopy and elemental analysis methods were used to identify the structures. They were put into PVC plastic products together with antimony tris (2-ethylhexyl thioglycolate) (Sb(2EHTG)3) under the suitable compounding, and their heat stability to PVC was studied. It is shown that these barium mercaptides have remarkable synergisms with antimony mercaptides and the long-term stabilizing effect of organoantimony stabilizer can be effectively improved, reducing the amount of antimony compounds so as to avoid the decrease of its stabilizing effect.

  1. Chemical abundances and kinematics of barium stars

    Science.gov (United States)

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Sales Silva, J. V.

    2016-07-01

    In this paper, we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scaleheight, radial velocities, abundances of the Na, Al, α-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars cannot be represented by a single Gaussian distribution. The abundances of α-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anticorrelated with the metallicity. Our kinematical analysis showed that 90 per cent of the barium stars belong to the thin disc population. Based on their luminosities, none of the barium stars are luminous enough to be an asymptotic giant branch star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  2. Titan's greenhouse and antigreenhouse effects

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1992-01-01

    Thermal mechanisms active in Titan's atmosphere are discussed in a brief review of data obtained during the Voyager I flyby in 1980. Particular attention is given to the greenhouse effect (GHE) produced by atmospheric H2, N2, and CH4; this GHE is stronger than that on earth, with CH4 and H2 playing roles similar to those of H2O and CO2 on earth. Also active on Titan is an antigreenhouse effect, in which dark-brown and orange organic aerosols block incoming solar light while allowing IR radiation from the Titan surface to escape. The combination of GHE and anti-GHE leads to a surface temperature about 12 C higher than it would be if Titan had no atmosphere.

  3. Seasonal Changes in Titan's Meteorology

    Science.gov (United States)

    Turtle, E. P.; DelGenio, A. D.; Barbara, J. M.; Perry, J. E.; Schaller, E. L.; McEwen, A. S.; West, R. A.; Ray, T. L.

    2011-01-01

    The Cassini Imaging Science Subsystem has observed Titan for 1/4 Titan year, and we report here the first evidence of seasonal shifts in preferred locations of tropospheric methane clouds. South \\polar convective cloud activity, common in late southern summer, has become rare. North \\polar and northern mid \\latitude clouds appeared during the approach to the northern spring equinox in August 2009. Recent observations have shown extensive cloud systems at low latitudes. In contrast, southern mid \\latitude and subtropical clouds have appeared sporadically throughout the mission, exhibiting little seasonality to date. These differences in behavior suggest that Titan s clouds, and thus its general circulation, are influenced by both the rapid temperature response of a low \\thermal \\inertia surface and the much longer radiative timescale of Titan s cold thick troposphere. North \\polar clouds are often seen near lakes and seas, suggesting that local increases in methane concentration and/or lifting generated by surface roughness gradients may promote cloud formation. Citation

  4. Life on Titan

    Science.gov (United States)

    Potashko, Oleksandr

    Volcanoes engender life on heavenly bodies; they are pacemakers of life. All planets during their period of formation pass through volcanism hence - all planets and their satellites pass through the life. Tracks of life If we want to find tracks of life - most promising places are places with volcanic activity, current or past. In the case of just-in-time volcanic activity we have 100% probability to find a life. Therefore the most perspective “search for life” are Enceladus, Io and comets, further would be Venus, Jupiter’s satellites, Saturn’s satellites and first of all - Titan. Titan has atmosphere. It might be result of high volcanic activity - from one side, from other side atmosphere is a necessary condition development life from procaryota to eucaryota. Existence of a planet means that all its elements after hydrogen formed just there inside a planet. The forming of the elements leads to the formation of mineral and organic substances and further to the organic life. Development of the life depends upon many factors, e.g. the distance from star/s. The intensity of the processes of the element formation is inversely to the distance from the star. Therefore we may suppose that the intensity of the life in Mercury was very high. Hence we may detect tracks of life in Mercury, particularly near volcanoes. The distance from the star is only one parameter and now Titan looks very active - mainly due to interior reason. Its atmosphere compounds are analogous to comet tail compounds. Their collation may lead to interesting result as progress occurs at one of them. Volcanic activity is as a source of life origin as well a reason for a death of life. It depends upon the thickness of planet crust. In the case of small thickness of a crust the probability is high that volcanoes may destroy a life on a planet - like Noachian deluge. Destroying of the life under volcano influences doesn’t lead to full dead. As result we would have periodic Noachian deluge or

  5. The TITAN magnet configuration

    International Nuclear Information System (INIS)

    The TITAN study uses copper-alloy ohmic-heating coils (OHC) to startup inductively a reversed-field-pinch (RFP) fusion reactor. The plasma equilibrium is maintained with a pair of superconducting equilibrium-field coils (EFCs). A second pair of copper EFCs provides the necessary trimming of the equilibrium field during plasma transients. A compact toroidal-field-coil (TFC) set is provided by an integrated blanket/coil (IBC). The IBC concept also is applied to the toroidal-field divertor coils. Steady-state operation is achieved with oscillating-field current drive, which oscillates at low amplitude and frequency the OHCs, EFCs, the TFCs, and divertor coils about their steady-state currents. An integrated magnet design, which uses low-field, low technology coils, and the related design basis is given. 18 refs

  6. From Titan's chemistry and exobiology to Titan's astrobiology

    Science.gov (United States)

    Raulin, François

    2015-04-01

    When the IDS proposal « Titan's chemistry and exobiology » was submitted to ESA 25 years ago, in the frame of what will become the Cassini-Huygens mission, Titan was already seen as a quite interesting planetary object in the solar system for Exobiology. Several organic compounds of prebiotic interest were identified in its atmosphere, which was thus was expected to be chemically very active, especially in term of organic processes. Atmospheric aerosols seemed to play a key role in this chemistry. Moreover, the presence of an internal aqueous ocean, compatible with life was suspected. A few years later, when astrobiology was (re)invented, Titan became one of the most interesting planetary target for this new (but very similar to exobiology) field. With the Cassini-Huygens mission, the exo/astrobiological interest of Titan has become more and more important. However, the mission has been providing a vision of Titan quite different from what it was supposed. Its atmospheric organic chemistry is very complex and starts in much higher zones than it was believed before, involving high molecular weight species in the ionosphere. Titan's surface appears to be far from homogeneous: instead of been covered by a global methane-ethane ocean, it is very diversified, with dunes, lakes, bright and dark areas, impact and volcanic craters with potential cryovolcanic activity. These various geological areas are continuously feeded by atmospheric aerosols, which represent an important step in the complexity of Titan's organic chemistry, but probably not the final one. Indeed, after being deposited on the surface, in the potential cryovolvanic zones, these particles may react with water ice and form compounds of exo/astrobiological interest, such as amino acids, purine and pyrimidine bases. Moreover, The Cassini-Huygens data strongly support the potential presence of an internal water ocean, which becomes less and less hypothetical and of great interest for exobiology. These

  7. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures

  8. The TITAN reversed-field-pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures.

  9. Coherent Dark Resonances in Atomic Barium

    CERN Document Server

    Dammalapati, U; Jungmann, K; Willmann, L

    2007-01-01

    The observation of dark-resonances in the two-electron atom barium and their influence on optical cooling is reported. In heavy alkali earth atoms, i.e. barium or radium, optical cooling can be achieved using n^1S_0-n^1P_1 transitions and optical repumping from the low lying n^1D_2 and n^3D_{1,2} states to which the atoms decay with a high branching ratio. The cooling and repumping transition have a common upper state. This leads to dark resonances and hence make optical cooling less inefficient. The experimental observations can be accurately modelled by the optical Bloch equations. Comparison with experimental results allows us to extract relevant parameters for effective laser cooling of barium.

  10. Titan Montgolfiere Terrestrial Test Bed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. In order to better plan this mission and...

  11. Titan Montgolfiere Terrestrial Test Bed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. To better plan this mission and create a...

  12. Refractory oxides containing aluminium and barium

    OpenAIRE

    Davies T.J.; Biedermann M.; Q-G. Chen; Emblem H. G.; Al-Douri W. A.

    1998-01-01

    Oxides containing aluminium and barium, optionally with chromium, are refractory with several possible industrial uses. A gel precursor of an oxide having the formula BaO.n(Al2xCr2yO3), where 1barium salt with a solution of an aluminium salt or a solution of an aluminium salt and a chromium III salt, then forming a gel which was fired to obtain the desired oxide. Filaments may be drawn as the gel is forming or extr...

  13. Organic chemistry on Titan: Surface interactions

    Science.gov (United States)

    Thompson, W. Reid; Sagan, Carl

    1992-01-01

    The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

  14. Structure of Titan's evaporites

    CERN Document Server

    Cordier, D; Barnes, J W; MacKenzie, S M; Bahers, T Le; Nna-Mvondo, D; Rannou, P; Ferreira, A G

    2015-01-01

    Numerous geological features that could be evaporitic in origin have been identified on the surface of Titan. Although they seem to be water-ice poor, their main properties -chemical composition, thickness, stratification- are essentially unknown. In this paper, which follows on a previous one focusing on the surface composition (Cordier et al., 2013), we provide some answers to these questions derived from a new model. This model, based on the up-to-date thermodynamic theory known as "PC-SAFT", has been validated with available laboratory measurements and specifically developed for our purpose. 1-D models confirm the possibility of an acetylene and/or butane enriched central layer of evaporitic deposit. The estimated thickness of this acetylene-butane layer could explain the strong RADAR brightness of the evaporites. The 2-D computations indicate an accumulation of poorly soluble species at the deposit's margin. Among these species, HCN or aerosols similar to tholins could play a dominant role. Our model pre...

  15. Structure of Titan's evaporites

    Science.gov (United States)

    Cordier, D.; Cornet, T.; Barnes, J. W.; MacKenzie, S. M.; Le Bahers, T.; Nna-Mvondo, D.; Rannou, P.; Ferreira, A. G.

    2016-05-01

    Numerous geological features that could be evaporitic in origin have been identified on the surface of Titan. Although they seem to be water-ice poor, their main properties - chemical composition, thickness, stratification - are essentially unknown. In this paper, which follows on a previous one focusing on the surface composition (Cordier, D., Barnes, J.W., Ferreira, A.G. [2013b]. Icarus 226(2),1431-1437), we provide some answers to these questions derived from a new model. This model, based on the up-to-date thermodynamic theory known as "PC-SAFT", has been validated with available laboratory measurements and specifically developed for our purpose. 1-D models confirm the possibility of an acetylene and/or butane enriched central layer of evaporitic deposit. The estimated thickness of this acetylene-butane layer could explain the strong RADAR brightness of the evaporites. The 2-D computations indicate an accumulation of poorly soluble species at the deposit's margin. Among these species, HCN or aerosols similar to tholins could play a dominant role. Our model predicts the existence of chemically trimodal "bathtub rings" which is consistent with what it is observed at the south polar lake Ontario Lacus. This work also provides plausible explanations to the lack of evaporites in the south polar region and to the high radar reflectivity of dry lakebeds.

  16. Large Particle Titanate Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    This research project was aimed at developing a synthesis technique for producing large particle size monosodium titanate (MST) to benefit high level waste (HLW) processing at the Savannah River Site (SRS). Two applications were targeted, first increasing the size of the powdered MST used in batch contact processing to improve the filtration performance of the material, and second preparing a form of MST suitable for deployment in a column configuration. Increasing the particle size should lead to improvements in filtration flux, and decreased frequency of filter cleaning leading to improved throughput. Deployment of MST in a column configuration would allow for movement from a batch process to a more continuous process. Modifications to the typical MST synthesis led to an increase in the average particle size. Filtration testing on dead-end filters showed improved filtration rates with the larger particle material; however, no improvement in filtration rate was realized on a crossflow filter. In order to produce materials suitable for column deployment several approaches were examined. First, attempts were made to coat zirconium oxide microspheres (196 µm) with a layer of MST. This proved largely unsuccessful. An alternate approach was then taken synthesizing a porous monolith of MST which could be used as a column. Several parameters were tested, and conditions were found that were able to produce a continuous structure versus an agglomeration of particles. This monolith material showed Sr uptake comparable to that of previously evaluated samples of engineered MST in batch contact testing.

  17. Magnetic properties of ferrite-titanate nanostructured composites synthesized by the polyol method and consolidated by spark plasma sintering

    Science.gov (United States)

    Acevedo, Ulises; Gaudisson, Thomas; Ortega-Zempoalteca, Raul; Nowak, Sophie; Ammar, Souad; Valenzuela, Raul

    2013-05-01

    Multiferroic systems formed by a mixing of a ferroelectric phase and a ferrimagnetic phase are receiving significant attention because of their wide possibilities for tailoring properties. In this work, the magnetic properties of the cobalt ferrite-barium titanate system were investigated on samples prepared by an original combination of synthesis methods. Cobalt ferrite and barium titanate nanoparticles were synthesized separately by hydrolysis of the metal acetates in a polyol method. Both materials were mixed in a 1:1 ratio and consolidated by spark plasma sintering at 500 °C for 5 min. A high density nanostructured ceramic was obtained with grains smaller than 100 nm and a density about 80% of the theoretical value. Magnetic hysteresis loops showed a hard magnet behavior, with a coercive field larger than cobalt ferrite alone prepared under the same conditions. δM reversible magnetization plots exhibited dipolar interactions with a maximum at the coercive field. These results are interpreted in terms of an efficient mixing of the components, which strongly decreases the magnetic percolation in the composite by separating ferrite grains by titanate grains.

  18. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  19. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... Commission found that the domestic interested party group response to its notice of institution (74 FR 31757... COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Notice of... chloride from China. SUMMARY: The Commission hereby gives notice that it will proceed with a full...

  20. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... established a schedule for the conduct of this review (74 FR 62587, November 30, 2010). Subsequently, counsel... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION:...

  1. Diurnal variations of Titan's ionosphere

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  2. Ion cyclotron waves at Titan

    Science.gov (United States)

    Russell, C. T.; Wei, H. Y.; Cowee, M. M.; Neubauer, F. M.; Dougherty, M. K.

    2016-03-01

    During the interaction of Titan's thick atmosphere with the ambient plasma, it was expected that ion cyclotron waves would be generated by the free energy of the highly anisotropic velocity distribution of the freshly ionized atmospheric particles created in the interaction. However, ion cyclotron waves are rarely observed near Titan, due to the long growth times of waves associated with the major ion species from Titan's ionosphere, such as CH4+ and N2+. In the over 100 Titan flybys obtained by Cassini to date, there are only two wave events, for just a few minutes during T63 flyby and for tens of minutes during T98 flyby. These waves occur near the gyrofrequencies of proton and singly ionized molecular hydrogen. They are left-handed, elliptically polarized, and propagate nearly parallel to the field lines. Hybrid simulations are performed to understand the wave growth under various conditions in the Titan environment. The simulations using the plasma and field conditions during T63 show that pickup protons with densities ranging from 0.01 cm-3 to 0.02 cm-3 and singly ionized molecular hydrogens with densities ranging from 0.015 cm-3 to 0.25 cm-3 can drive ion cyclotron waves with amplitudes of ~0.02 nT and of ~0.04 nT within appropriate growth times at Titan, respectively. Since the T98 waves were seen farther upstream than the T63 waves, it is possible that the instability was stronger and grew faster on T98 than T63.

  3. The Titan Saturn System Mission

    Science.gov (United States)

    Coustenis, A.; Lunine, J.; Lebreton, J.; Matson, D.; Erd, C.; Reh, K.; Beauchamp, P.; Lorenz, R.; Waite, H.; Sotin, C.; Tssm Jsdt, T.

    2008-12-01

    A mission to return to Titan after Cassini-Huygens is a high priority for exploration. Recent Cassini-Huygens discoveries have revolutionized our understanding of the Titan system, rich in organics, containing a vast subsurface ocean of liquid water, surface repositories of organic compounds, and having the energy sources necessary to drive chemical evolution. With these recent discoveries, interest in Titan as the next scientific target in the outer Solar System is strongly reinforced. Cassini's discovery of active geysers on Enceladus adds an important second target in the Saturn system. The mission concept consists of a NASA-provided orbiter and an ESA-provided probe/lander and a Montgolfiere. The mission would launch on an Atlas 551 around 2020, travelling to Saturn on an SEP gravity assist trajectory, and reaching Saturn about 9.5 years later. The flight system would go into orbit around Saturn for about 2 years. During the first Titan flyby, the orbiter would release the lander to target a large northern polar sea, Kraken Mare, and the balloon system to a mid latitude region. During the tour phase, TSSM will perform Saturn system and Enceladus science, with at least 5 Enceladus flybys. Instruments aboard the orbiter will map Titan's surface at 50 m resolution in the 5 micron window, provide a global data set of topography and sound the immediate subsurface, sample complex organics, provide detailed observations of the atmosphere, and quantify the interaction of Titan with the Saturn magnetosphere. A subset of the instruments would provide spectra, imaging, plume sampling and particles and fields data on Enceladus. Instruments aboard the balloon will acquire high resolution vistas of the surface of Titan as the balloon cruises at 10 km altitude, as well as make compositional measurements of the surface, detailed sounding of crustal layering, and chemical measurements of aerosols. A magnetometer, will permit sensitive detection of induced or intrinsic fields

  4. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.P. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Duarte, G.W. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Research Group in Technology and Information, Centro Universitário Barriga Verde (UNIBAVE), Santa Catarina, SC (Brazil); Caldart, C. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Kniess, C.T. [Post-Graduate Program in Professional Master in Management, Universidade Nove de Julho, São Paulo, SP (Brazil); Montedo, O.R.K.; Rocha, M.R. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Riella, H.G. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduate Program in Environmental Science, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil); Post-Graduate Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil)

    2015-11-15

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound.

  5. Obtaining the highly pure barium titanate nanocrystals by a new approach

    Energy Technology Data Exchange (ETDEWEB)

    Ashiri, Rouholah, E-mail: ro_ashiri@yahoo.com; Heidary Moghadam, Ali; Ajami, Reza

    2015-11-05

    Purity and synthesis temperature of nanocrystals are key challenges facing the scientific community. Herein a novel solid-state approach to synthesize fine BaTiO{sub 3} nanocrystals with narrow size distribution using a high-speed ball-milling process is reported. In order to improve the kinetics of this reaction, the starting materials, BaCO{sub 3} and TiO{sub 2}, were milled for 10 h before mixing and initiating the synthesis reaction. The contribution of this step to the BaTiO{sub 3} formation is analyzed by XRD diffractometry and FE-SEM techniques. It was found that the use of the mechanically activated starting materials favors the decomposition of BaCO{sub 3} at low temperatures and improves the Ba{sup 2+} diffusion through the formed BaTiO{sub 3} layer. In consequence, very fine BaTiO{sub 3} nanocrystals free from the secondary phases were obtained at a lower temperature in contrast to the previous works. - Highlights: • Very fine BaTiO{sub 3} nanocrystals were obtained at a lower temperature. • Method is able to obtain highly-pure BTO nanocrystals. • The approach is simple, and useful for large-scale production purposes.

  6. Effect of Fe3+ substitution on structural, optical and magnetic properties of barium titanate ceramics

    International Nuclear Information System (INIS)

    Multiferroic BaTi1−xFexO3 (0≤x≤0.12) materials were synthesized using the solid-state reaction method. The influence of Fe on the crystalline structure, the electronic structure, the optical properties and the magnetic property of BaTi1−xFexO3 samples were investigated. The obtained X-ray diffraction patterns, Raman and UV–vis spectra showed that the structure of the material sensitively depends on Fe dopant content, x, and transforms gradually from the tetragonal (P4mm) phase to the hexagonal (P63/mmc) one with increasing x. The photoluminescence emission of BaTi1−xFexO3 was attributed to structural disorder. All of the samples exhibit both ferroelectricity and ferromagnetism at room temperature. The relaxor like behavior was observed for all samples. The magnetization at a magnetic field of 1 T abnormally depends on x, increases up to 0.1 then decreases monotonously afterward. This anomaly in the magnetic behavior can be explained in terms of the changes in the oxidation state of ions such as the Fe3+-to-Fe4+ and/or Ti4+-to-Ti3+ change induced by oxygen vacancies. The substitution of Fe into Ti sites also causes the changes in the conductivity of the material and impurity (acceptor) levels in the band gap, which can be evident from the absorption spectra, and time-dependent leakage current measured at room temperature

  7. Epitaxially-Grown Europium-Doped Barium Titanate Films on Various Substrates for Red Emission.

    Science.gov (United States)

    Hwang, Kyu-Seog; Jeon, Young-Sun; Lee, Young-Hwan; Hwangbo, Seung; Kim, Jin-Tae

    2015-10-01

    Intense red photoluminescence under ultraviolet excitation was observed in epitaxially-grown europium-doped perovskite BaTiO3 thin films deposited on the SrTiO3 (100), MgO (100) and sapphire (0001) substrates using metal carboxylate complexes. Precursor films prepared by spin coating were pyrolyzed at 250 °C for 120 min in argon, followed by final annealing at 850 °C for 60 min in argon. Crystallinity and epitaxy of the films were analyzed by X-ray diffraction θ-2θ scan and pole-figure analysis. Photoluminescence of the thin films at room temperature under 254 nm was confirmed by a fluorescent spectrophotometer. The obtained epitaxial BaTiO3 thin films on the SrTiO3 (100) and MgO (100) substrates show an intense red-emission lines at 615 nm corresponding to the (5)D0 --> (7)F2 transitions on Eu(3+) with broad bands at 595 and 650 nm. PMID:26726427

  8. STRUCTURAL CHARACTERISTICS & DIELECTRIC PROPERTIES OF TANTALUM OXIDE DOPED BARIUM TITANATE BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Md. Fakhrul Islam

    2013-01-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mole % Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90 % was achieved for 0.5 and 1.0 mole %Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0.5 mole % Ta2O5. Although fine grain size down to 200 - 300 nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000 - 14000 was found in the temperature range of 55 to 80 °C, for 1.0 mole % Ta2O5 doped samples with corresponding shift of Curie point to ~82 °C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  9. Investigation of resistive switching in barium strontium titanate thin films for memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wan

    2010-11-17

    Resistive random access memory (RRAM) has attracted much attention due to its low power consumption, high speed operation, non-readout disturbance and high density integration potential and is regarded as one of the most promising candidates for the next generation non-volatile memory. The resistive switching behavior of Mn-doped BaSrTiO{sub 3} (BST) thin films with different crystalline properties was investigated within this dissertation. The laser fluence dependence was checked in order to optimize the RRAM properties. Although the film epitaxial quality was improved by reducing the laser energy during deposition process, the yields fluctuated and only 3% RRAM devices with highest epitaxial quality of BST film shows resistive switching behavior instead of 67% for the samples with worse film quality. It gives a clue that the best thin film quality does not result in the best switching performance, and it is a clear evidence of the importance of the defects to obtain resistive switching phenomena. The bipolar resistive switching behavior was studied with epitaxial BST thin films on SRO/STO. Compared to Pt top electrode, the yield, endurance and reliability were strongly improved for the samples with W top electrode. Whereas the samples with Pt top electrode show a fast drop of the resistance for both high and low resistance states, the devices with W top electrode can be switched for 10{sup 4} times without any obvious degradation. The resistance degradation for devices with Pt top electrode may result from the diffusion of oxygen along the Pt grain boundaries during cycling whereas for W top electrode the reversible oxidation and reduction of a WO{sub x} layer, present at the interface between W top electrode and BST film, attributes to the improved switching property. The transition from bipolar to unipolar resistive switching in polycrystalline BST thin films was observed. A forming process which induces a metallic low resistance state is prerequisite for the observation of unipolar switching behavior. The absence of unipolar switching in single crystalline samples may relate to space charge depletion layers at grain boundaries and their impact on the electronic conduction properties as well as the different local heat transfer in thin films. By controlling the switching voltage, the bipolar and unipolar resistive switching can be alternated in polycrystalline BST thin films. The bipolar/unipolar alternation is dynamically repeatable and the alternation may relate to the local modification of broken filaments by breakdown or oxygen vacancy movement. (orig.)

  10. Direct-write inkjet printing for fabrication of barium strontium titanate-based tunable circuits

    International Nuclear Information System (INIS)

    Tunable capacitors with up to 30% tuning and a loss tangent (tanδ) less than 0.002 at 1 MHz were fabricated from Ba0.6Sr0.4TiO3 (BST) films using inkjet-printed liquid metalorganic precursors. BST films of various thicknesses were produced by printing multiple stacks of the individual inkjet-printed layers. The dielectric constant of the printed films increased as a function of thickness. The largest dielectric constant, 1000, and the highest tunability, 30%, were measured on a 420 nm thick film, the thickest film studied in this work. Spray-printed silver contacts were employed and demonstrated good adhesion and good electrical contact to the inkjet-printed BST films. This also demonstrated proof of principle for direct-write printing of metal contacts onto BST films from metalorganic sources

  11. Structural and dielectric properties of barium strontium titanate produced by high temperature hydrothermal method

    International Nuclear Information System (INIS)

    The preparation procedure, structural and dielectric properties of hydrothermally derived BaxSr1-xTiO3 (BST) were studied. BST with initial Ba compositions of 75, 80, 85 and 90 mol.% were prepared by a high temperature hydrothermal synthesis. The obtained powders were pressed into pellet, cold isostatically pressed and sintered at 1200 deg. C for 3 hours. The phase compositions and lattice parameters of the as prepared powders and sintered samples were analysed using X-ray diffractometry. A fitting software was used to analyse the XRD spectra to separate different phases. It was found that BST powder produced by the high temperature hydrothermal possessed a two-phase structure. This structure became more homogeneous during sintering due to interdiffusion but a small amount of minor phase can still be traced. Samples underwent an abnormal grain growth, whereby some grains grow faster than the other due to the presence of two-phase structure. The grain size increased with increasing Ba amount. Dielectric constant and polarisation increased with increasing Ba content but it was also affected by the electronic state and grain size of the compositions

  12. Influence of Tm-doping on microstructure and luminescence behavior of barium strontium titanate thick films

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jingyang [School of Materials Science and Engineering, Hubei University, Wuhan, 430062 (China); Zhang Tianjin, E-mail: tj65zhang@yahoo.com.cn [School of Materials Science and Engineering, Hubei University, Wuhan, 430062 (China); Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan, 430062 (China); Pan Ruikun; Ma Zhijun; Wang Jinzhao [School of Materials Science and Engineering, Hubei University, Wuhan, 430062 (China)

    2012-01-15

    Tm-doped Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} thick films were prepared by the screen-printing technique on the alumina substrate. The microstructure of the Tm-doped BST thick films was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy, respectively. All the samples showed a typical perovskite polycrystalline structure when sintered at 1260 Degree-Sign C. The substitution behavior of Tm{sup 3+} ion in BST was found to change with increasing the Tm{sup 3+} concentration. The observed Tm-related red emission reaches the maximum at 0.2 mol% Tm{sup 3+} concentration. The effects of concentration quenching on the luminescence intensity were discussed.

  13. Structural Characteristics & Dielectric Properties of Tantalum Oxide Doped Barium Titanate Based Materials

    Directory of Open Access Journals (Sweden)

    Rubayyat Mahbub

    2012-11-01

    Full Text Available In this research, the causal relationship between the dielectric properties and the structural characteristics of 0.5 & 1.0 mol% Ta2O5 doped BaTiO3 based ceramic materials were investigated under different sintering conditions. Dielectric properties and microstructure of BaTio3 ceramics were significantly influenced by the addition of a small amount of Ta2O5. Dielectric properties were investigated by measuring the dielectric constant (k as a function of temperature and frequency. Percent theoretical density (%TD above 90% was achieved for 0.5 and 1.0 mol% Ta2O5 doped BaTiO3. It was observed that the grain size decreased markedly above a doping concentration of 0·5 mol% Ta2O5. Although fine grain size down to 200-300nm was attained, grain sizes in the range of 1-1.8µm showed the most alluring properties. The fine-grain quality and high density of the Ta2O5 doped BaTiO3 ceramic resulted in tenfold increase of dielectric constant. Stable value of dielectric constant as high as 13000-14000 was found in the temperature range of  55 to 80°C, for 1.0 mol% Ta2O5 doped samples with corresponding shift of Curie point to ~82°C. Experiments divulged that incorporation of a proper content of Ta2O5 in BaTiO3 could control the grain growth, shift the Curie temperature and hence significantly improve the dielectric property of the BaTiO3 ceramics.

  14. Characterization of Bismuth-Sodium-Barium-Titanate Electro ceramics Synthesized by Mechanical Alloying

    International Nuclear Information System (INIS)

    In this study, the synthesis of BNBT6 electro ceramics by milling was evaluated. The chemical composition, structural analysis, and particle size evolution of the as-milled powders were studied by X-ray florescence analyzer (XRF), X-ray diffractometer (XRD), and transmission electron microscopy (TEM), respectively. The chemical composition assessment indicated that the amount of impurities is negligible. The structural analysis revealed that the crystallite size was decreased to nano-size scales and the amorphization process was developed. It was found that perovskite and pyrochlore phases were nucleated at initial stages of milling and after sufficient milling times, BNBT phase prevailed over the other phases. (author)

  15. Electrical characterization of zirconium substituted barium titanate using complex impedance spectroscopy

    Indian Academy of Sciences (India)

    Priyanka; A K Jha

    2013-02-01

    This paper reports complex impedance analysis of polycrystalline complex perovskite structured BaZr0.025Ti0.975O3 prepared by solid state reaction method. XRD analysis reveals the formation of single phase perovskite structure. SEM has been used to investigate grain morphology of the material. Impedance plots have been used as a tool to analyse electrical properties of the sample as a function of frequency and temperature. Bulk resistance is observed to decrease with an increase in temperature showing a typical negative temperature coefficient of resistance (NTCR) type behaviour. Nyquist (Cole–Cole) plots show both inter and intra grain boundary effects. Relaxation time is found to decrease with increasing temperature and it obeys the Arrhenius relationship. The variation of d.c. and a.c. conductivity as a function of temperature is also reported.

  16. Nanocrystalline barium titanate films on flexible plastic substrates via pulsed laser annealing

    Science.gov (United States)

    Tsagarakis, Evangelos D.; Lew, Connie; Thompson, Michael O.; Giannelis, Emmanuel P.

    2006-11-01

    The drive towards ubiquitous electronics requires fundamental shifts in our approach to microelectronic fabrication as well as advances in materials and processing technologies. For large area electronics, low cost manufacturing, including roll-to-roll and printing technologies, will be required. These techniques present continuing challenges to develop processing technologies compatible with the low thermal budgets required for flexible polymeric substrates. The authors report here the deposition and dielectric properties of nanocrystalline BaTiO3 films on polyethylene terephthalate utilizing laser annealing as part of their effort to develop methods and tools for depositing various functional coatings and films on flexible substrates.

  17. Interfacial diffusion in a MOCVD grown barium titanate film[Metal Organic Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Datta, A.; Chattopadhyay, S.; Richter, A.G.; Kmetko, J.; Lee, C.B.

    2000-07-01

    A combination of two nondestructive techniques, Grazing Incidence X-ray Reflectivity and High Resolution X-ray Diffraction, is used to study (at around 10{angstrom} resolution) the composition profile across a 500{angstrom} thick film of BaTiO{sub 3} grown epitaxially on (100) MgO by MOCVD. Results form both studies indicate diffusion of Mg to about 250{angstrom} into the film at film-substrate interface, consistent with the diffuse ferroelectric phase transition observed in this film. The lattice parameter a shows a progressive decrease as the authors move into the film from the interface, and an anomalously low value in the Mg-free portion of the film.

  18. Investigation of resistive switching in barium strontium titanate thin films for memory applications

    International Nuclear Information System (INIS)

    Resistive random access memory (RRAM) has attracted much attention due to its low power consumption, high speed operation, non-readout disturbance and high density integration potential and is regarded as one of the most promising candidates for the next generation non-volatile memory. The resistive switching behavior of Mn-doped BaSrTiO3 (BST) thin films with different crystalline properties was investigated within this dissertation. The laser fluence dependence was checked in order to optimize the RRAM properties. Although the film epitaxial quality was improved by reducing the laser energy during deposition process, the yields fluctuated and only 3% RRAM devices with highest epitaxial quality of BST film shows resistive switching behavior instead of 67% for the samples with worse film quality. It gives a clue that the best thin film quality does not result in the best switching performance, and it is a clear evidence of the importance of the defects to obtain resistive switching phenomena. The bipolar resistive switching behavior was studied with epitaxial BST thin films on SRO/STO. Compared to Pt top electrode, the yield, endurance and reliability were strongly improved for the samples with W top electrode. Whereas the samples with Pt top electrode show a fast drop of the resistance for both high and low resistance states, the devices with W top electrode can be switched for 104 times without any obvious degradation. The resistance degradation for devices with Pt top electrode may result from the diffusion of oxygen along the Pt grain boundaries during cycling whereas for W top electrode the reversible oxidation and reduction of a WOx layer, present at the interface between W top electrode and BST film, attributes to the improved switching property. The transition from bipolar to unipolar resistive switching in polycrystalline BST thin films was observed. A forming process which induces a metallic low resistance state is prerequisite for the observation of unipolar switching behavior. The absence of unipolar switching in single crystalline samples may relate to space charge depletion layers at grain boundaries and their impact on the electronic conduction properties as well as the different local heat transfer in thin films. By controlling the switching voltage, the bipolar and unipolar resistive switching can be alternated in polycrystalline BST thin films. The bipolar/unipolar alternation is dynamically repeatable and the alternation may relate to the local modification of broken filaments by breakdown or oxygen vacancy movement. (orig.)

  19. Adsorption of water-soluble polymers onto barium titanate and its effect on colloidal stability.

    NARCIS (Netherlands)

    Laat, de A.W.M.

    1995-01-01

    Ceramic products are usually made from powders which are processed into a green body, with a shape dictated by the final product. Organic binders are used to give the green product sufficient mechanical strength. A sintering process at high temperature converts the green body into the final ceramic

  20. Ferroelectric properties of barium strontium titanate thin films grown by RF co-sputtering

    International Nuclear Information System (INIS)

    In this work, we present the variation of the ferroelectric properties of Ba1-xSrxTiO3 films deposited on Pt/TiO2/SiO2/Si substrates by RF co-sputtering with 0≤x≤1. The co-sputtering was done using a single magnetron with BaTiO3/SrTiO3 targets in a pie mosaics configuration. Smooth and uniform films were obtained using the same conditions of growth and annealing temperature. The X-ray diffraction and EDS results show that the processes were managed to obtain crystalline materials with x from 0 to 1. The behaviour of P-E loops suggests that the ferroelectric properties of the films were tuned by changing the concentration of the cation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Fabrication and electrical properties of barium titanate based solid solution nanocube assembly films

    Science.gov (United States)

    Mimura, Ken-ichi; Kato, Kazumi

    2016-10-01

    Ba(Zr x ,Ti1- x )O3 nanocubes (BZT x NCs) of 15 nm size were synthesized by a hydrothermal method with Ti and Zr aqueous compounds and a surfactant at the Zr contents (x) of 0.1 and 0.2. An individual BZT0.2 NC is a high-quality single crystal without any voids. The elemental mapping of a BZT0.2 NC showed a homogeneous Zr distribution in the NC. BZT x NC assembly films were fabricated by a dip-coating method. BZT x NC assemblies after heat treatment at 850 °C formed joined interfaces between the NCs. Raman spectra appearing at approximately 305 and 250 cm-1 in the BT NC assembly merged into a single band around 288 cm-1 in the BZT0.2 NC assembly. These results indicate that Zr ions substituted a portion of Ti sites homogeneously. Relaxor-like piezoresponse properties of BZT x NC assemblies were obtained by piezoresponse force microscopy (PFM). The BZT0.1 NC assembly had a high saturation d 33-PFM value of 42 pm/V.

  2. Cyclodextrin-grafted barium titanate nanoparticles for improved dispersion and stabilization in water-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Serra-Gómez, R. [Universidad de Navarra, Departamento de Química y Edafología (Spain); Martinez-Tarifa, J. M. [Universidad Carlos III de Madrid, Departamento de Ingeniería Eléctrica (Spain); González-Benito, J. [Universidad Carlos III de Madrid, Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IQMAAB (Spain); González-Gaitano, G., E-mail: gaitano@unav.es [Universidad de Navarra, Departamento de Química y Edafología (Spain)

    2016-01-15

    Ceramic nanoparticles with piezoelectric properties, such as BaTiO{sub 3} (BT), constitute a promising approach in the fields of nanocomposite materials and biomaterials. In the latter case, to be successful in their preparation, the drawback of their fast aggregation and practically null stability in water has to be overcome. The objective of this investigation has been the surface functionalization of BaTiO{sub 3} nanoparticles with cyclodextrins (CDs) as a way to break the aggregation and improve the stability of the nanoparticles in water solution, preventing and minimizing their fast precipitation. As a secondary goal, we have achieved extra-functionality of the nanoparticles, bestowed from the hydrophobic cavity of the macrocycle, which is able to lodge guest molecules that can form inclusion complexes with the oligosaccharide. The nanoparticle functionalization has been fully tracked and characterized, and the cytotoxicity of the modified nanoparticles with fibroblasts and pre-osteoblasts cell lines has been assessed with excellent results in a wide range of concentrations. The modified nanoparticles were found to be suitable for the easy preparation of nanocomposite hydrogels, via dispersion in hydrophilic polymers of typical use in biomedical applications (PEG, Pluronics, and PEO), and further processed in the form of films via water casting, showing very good results in terms of homogeneity in the dispersion of the filler. Likewise, as examples of application and with the aim of exploring a different range of nanocomposites, rhodamine B was included in the macrocycles as a model molecule, and films prepared from a thermoplastic matrix (EVA) via high-energy ball milling have been tested by impedance spectroscopy to discuss their dielectric properties, which indicated that even small modifications in the surface of the nanoparticles generate a different kind of interaction with the polymeric matrix. The CD-modified nanoparticles are thus suitable for easy preparation of the water-based nanocomposites either as hydrogels or as nanocomposites based on thermoplastic matrices.

  3. Synthesis, Microstructure and the Crystalline Structure of the Barium Titanate Ceramics Doped with Lanthanum

    Directory of Open Access Journals (Sweden)

    Wodecka-Duś B.

    2013-12-01

    Full Text Available W prezentowanej pracy przeprowadzono badania ceramiki BaTiO3 i Ba1-xLąxTi1-x/4O3 (BLT dla koncentracji z prze- działu 0,001< x <0,004 (0,l-0,4mol.% La. Ceramikę BLT wytworzono z mieszaniny prostych tlenków La203, TiOi i BaCOj (wszystkie o czystości 99,9+%, Aldrich Chemical Co. Proszki ceramiczne otrzymano metodą konwencjonalną w stanie stałym (metodą MOM i poddano badaniu mikrostruktury i struktury krystalicznej. Mieszaniny proszków poddano analizie termicznej. Wyniki analizy termicznej określiły optymalną temperaturę syntezy oraz procesy zachodzące podczas ogrzewania proszków. Następnie proszki formowano w dyski pod ciśnieniem 300MPa w matrycach ze stali nierdzewnej o średnicy 10 mm. Syntezę przeprowadzono w Ts =950°C t =2godz. Ostatnim krokiem technologii było bezciśnieniowe spiekanie metodą swobodnego spiekania w T = 1350^ przez / =2 godziny. Morfologię otrzymanego materiału ceramicznego obserwowano metodą skaningowej mikroskopii elektronowej. Ceramikę BLT badano również pod względem składu chemicznego metodą EDS. Analizę strukturalną przeprowadzono metodą dyfrakcji rentgenowskiej. Badania mikrostruktury i struktury krystalicznej ceramiki przeprowadzono w temperaturze pokojowej. Badania EDS potwierdziły zachowanie stechiometrii otrzymanych próbek według wzoru chemicznego. Rentgenowska analiza dyfrakcyjna potwierdziły wytworzenie pożądanej struktury krystalicznej zarówno czystej ceramiki BaTiOj jak i z domieszką Lau. Otrzymana ceramika wykazuje strukturę typu perowskitu A BO? o symetrii tetragonalnej P4 mm. Stwierdzono, że wraz ze wzrostem stężenia La3* w BaTiOj następuje zmniejszenie wielkości ziam krystalicznych, zmniejszenie średniego wymiaru krystalitów, zmniejszenie objętości komórki elementarnej oraz wzrost obliczonej rentgenowskiej gęstości.

  4. Highly efficient visible light mediated azo dye degradation through barium titanate decorated reduced graphene oxide sheets

    Science.gov (United States)

    Rastogi, Monisha; Kushwaha, H. S.; Vaish, Rahul

    2016-03-01

    This study investigates BaTiO3 decorated reduced graphene oxide sheets as a potential visible light active catalyst for dye degradation (Rhodamine B). The composites were prepared through conventional hydrothermal synthesis technique using hydrazine as a reducing agent. A number of techniques have been employed to affirm the morphology, composition and photocatalytic properties of the composites; these include UV-visible spectrophotoscopy that assisted in quantifying the concentration difference of Rhodamine B. The phase homogeneity of the composites was examined through x-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) was employed to confirm the orientation of the BaTiO3 particles over the reduced graphene oxide sheets. Photoluminescence (PL) emission spectra assisted in determining the surface structure and excited state of the catalyst. Fourier transformed-infrared (FTIR) spectra investigated the vibrations and adsorption peak of the composites, thereby ascertaining the formation of reduced graphene oxide. In addition, diffuse reflectance spectroscopy (DRS) demonstrated an enhanced absorption in the visible region. The experimental investigations revealed that graphene oxide acted as charge collector and simultaneously facilitated surface adsorption and photo-sensitization. It could be deduced that BaTiO3-reduced graphene oxide composites are of significant interest the field of water purification through solar photocatalysis. [Figure not available: see fulltext.

  5. Magnetoelectric effect in cobalt ferrite–barium titanate composites and their electrical properties

    Indian Academy of Sciences (India)

    R P Mahajan; K K Patankar; M B Kothale; S C Chaudhari; V L Mathe; S A Patil

    2002-05-01

    CoFe2O4–BaTiO3 composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in the temperature range 300 K to 600 K were measured. Variation of dielectric constant (') with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac conductivity was derived from dielectric constant (') and loss tangent (tan ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric conversion factor has been studied as a function of magnetic field.

  6. Conductivity, dielectric behaviour and magnetoelectric effect in copper ferrite–barium titanate composites

    Indian Academy of Sciences (India)

    R P Mahajan; K K Patankar; M B Kothale; S A Patil

    2000-08-01

    Composites of CuFe2O4 and BaTiO3 were prepared using a conventional ceramic double sintering process. The presence of both phases was confirmed by X-ray diffraction. The variations of resistivity and thermo emf with temperature in these samples were studied. All the composites showed -type behaviour. The variation of dielectric constant (') in the frequency range 100 Hz to 1 MHz and with temperature at constant frequency were studied. The conduction phenomenon was explained on the basis of a small polaronhopping model. Also confirmation of this phenomenon was made with the help of a.c. conductivity measurements. The static value of the magnetoelectric conversion factor, i.e. d.c. (ME)H was studied as a function of intensity of the magnetic field. The maximum value of ME coefficient was observed for 75% ferroelectric phase composite.

  7. Titan Aeromony and Climate Workshop

    Science.gov (United States)

    Bézard, Bruno; Lavvas, Panayotis; Rannou, Pascal; Sotin, Christophe; Strobel, Darrell; West, Robert A.; Yelle, Roger

    2016-06-01

    The observations of the Cassini spacecraft since 2004 revealed that Titan, the largest moon of Saturn, has an active climate cycle with a cloud cover related to the large scale atmospheric circulation, lakes of methane and hyrdrocarbons with variable depth, a dried fluvial system witnessing a past wetter climate, dunes, and deep changes in the weather and atmospheric structure as Titan went through the North Spring equinox. Moreover, the upper atmosphere is now considered the cradle of complex chemistry leading to aerosol formation, as well as the manifestation place of atmospheric waves. However, as the Cassini mission comes to its end, many fundamental questions remain unresolved... The objective of the workshop is to bring together international experts from different fields of Titan's research in order to have an overview of the current understanding, and to determine the remaining salient scientific issues and the actions that could be implemented to address them. PhD students and post-doc researchers are welcomed to present their studies. This conference aims to be a brainstorming event leaving abundant time for discussion during oral and poster presentations. Main Topics: - Atmospheric seasonal cycles and coupling with dynamics. - Composition and photochemistry of the atmosphere. - Formation and evolution of aerosols and their role in the atmosphere. - Spectroscopy, optical properties, and radiative transfer modeling of the atmosphere. - Surface composition, liquid reservoirs and interaction with atmosphere. - Evolution of the atmosphere. - Titan after Cassini, open questions and the path forward.

  8. Organic chemistry in Titan's atmosphere

    Science.gov (United States)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  9. Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

    Science.gov (United States)

    Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

    2016-04-01

    Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

  10. Production of translationally cold barium monohalide ions

    OpenAIRE

    DePalatis, M. V.; Chapman, M.S.

    2013-01-01

    We have produced sympathetically cooled barium monohalide ions BaX$^+$ (X = F, Cl, Br) by reacting trapped, laser cooled Ba$^+$ ions with room temperature gas phase neutral halogen-containing molecules. Reaction rates for two of these (SF$_6$ and CH$_3$Cl) have been measured and are in agreement with classical models. BaX$^+$ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.

  11. Chemical abundances and kinematics of barium stars

    CERN Document Server

    de Castro, D B; Roig, F; Jilinski, E; Drake, N A; Chavero, C; Silva, J V Sales

    2016-01-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, $alpha$-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code {\\sc moog}. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of $alpha$-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heav...

  12. Sources of Pressure in Titan's Plasma Environment

    CERN Document Server

    Achilleos, N; Bertucci, C; Guio, P; Romanelli, N; Sergis, N

    2013-01-01

    In order to analyze varying plasma conditions upstream of Titan, we have combined a physical model of Saturn's plasmadisk with a geometrical model of the oscillating current sheet. During modeled oscillation phases where Titan is furthest from the current sheet, the main sources of plasma pressure in the near-Titan space are the magnetic pressure and, for disturbed conditions, the hot plasma pressure. When Titan is at the center of the sheet, the main source is the dynamic pressure associated with Saturn's cold, subcorotating plasma. Total pressure at Titan (dynamic plus thermal plus magnetic) typically increases by a factor of five as the current sheet center is approached. The predicted incident plasma flow direction deviates from the orbital plane of Titan by < 10 deg. These results suggest a correlation between the location of magnetic pressure maxima and the oscillation phase of the plasmasheet.

  13. Lanthanide doped strontium-barium cesium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  14. TiME - The Titan Mare Explorer

    Science.gov (United States)

    Stofan, E.; Lorenz, R.; Lunine, J.; Bierhaus, E. B.; Clark, B.; Mahaffy, P. R.; Ravine, M.

    The Titan Mare Explorer (TiME) is a Discovery-class mission concept that underwent a detailed Phase A study in 2011-2012. The mission would splashdown a capsule on Titan's ethane sea Ligeia Mare as early as the summer of 2023, and would spend multiple Titan days performing science measurements and transmitting data directly back to Earth. This paper reviews briefly the mission concept.

  15. Titan Montgolfiere Buoyancy Modulation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Titan is ideally suited for balloon exploration due to its low gravity and dense atmosphere. Current NASA mission architectures baseline Montgolfiere balloon...

  16. The Global Energy Balance of Titan

    Science.gov (United States)

    Li, Liming; Nixon, Conor A.; Achterberg, Richard K.; Smith, Mark A.; Gorius, Nicolas J. P.; Jiang, Xun; Conrath, Barney J.; Gierasch, Peter J.; Simon-Miller, Amy A.; Flasar, F. Michael; Baines, Kevin H.; Ingersoll, Andrew P.; West, Robert A.; Vasavada, Ashwin R.; Ewald, Shawn P.

    2011-01-01

    We report the first measurement of the global emitted power of Titan. Longterm (2004-2010) observations conducted by the Composite Infrared Spectrometer (CIRS) onboard Cassini reveal that the total emitted power by Titan is (2.84 plus or minus 0.01) x 10(exp 8) watts. Together with previous measurements of the global absorbed solar power of Titan, the CIRS measurements indicate that the global energy budget of Titan is in equilibrium within measurement error. The uncertainty in the absorbed solar energy places an upper limit on the energy imbalance of 5.3%.

  17. Nitrogen fractionation in Titan's aerosols

    Science.gov (United States)

    Carrasco, Nathalie; Kuga, Maia; Marty, Bernard; Fleury, Benjamin; Marrocchi, Yves

    2016-06-01

    A strong nitrogen fractionation is found by Cassini in Titan's atmosphere with the detection of 15N-rich HCN relative to N2. Photodissociation of N2 associated or not to self-shielding might involve 15N-rich radicals prone to incorporation into forming organics. However the isotopic composition is only available for very simple gaseous N-bearing compounds, and the propagation and conservation of such a large N-isotopic fractionation upon polymerization is actually out of reach with the instruments onboard Cassini. We will therefore present a first laboratory investigation of the possible enrichment in the solid organic aerosols. We will also discuss the space instrumention required in the future to answer this pending issue on Titan.

  18. Oxygen Chemistry in Titan's Atmosphere

    Science.gov (United States)

    Wilson, E. H.; Atreya, S. K.

    2002-09-01

    Oxygen chemistry in the atmosphere of Titan is controlled by the presence of CO and a likely influx of extraplanetary oxygen. The presence of water vapor, corroborated by the Infrared Space Observatory (ISO) stratospheric detection [1], combined with CO induces the formation of CO2, which has also been observed [2]. However, the high CO/H2O ratio in Titan's atmosphere causes the propagation of oxygen chemistry to follow a different path than what is predicted for the Jovian planets. Specifically, the efficient CO recycling mechanisms serve to inhibit significant formation of larger oxygen compounds such as CH3OH (methanol) and CH2CO (ketene). The results of a 1-D photochemical model are presented in the context of identifying possible oxygen compounds that might be detected by the Cassini/Huygens mission which will arrive at Titan in 2004. This work was supported by the NASA Planetary Atmospheres Program and by the GCMS Project of the Cassini/Huygens mission. [1] A. Coustenis et al., Astron. Astrophys., 336, L85-L89, 1998. [2] A. Coustenis et al., Icarus, 80, 54-76, 1989.

  19. Crystal structure of 2-methyl-1H-imidazol-3-ium aquatrichlorido(oxalato-κ2O,O′stannate(IV

    Directory of Open Access Journals (Sweden)

    Mouhamadou Birame Diop

    2015-05-01

    Full Text Available The tin(IV atom in the complex anion of the title salt, (C4H7N2[Sn(C2O4Cl3(H2O], is in a distorted octahedral coordination environment defined by three chlorido ligands, an oxygen atom from a water molecule and two oxygen atoms from a chelating oxalate anion. The organic cation is linked through a bifurcated N—H...O hydrogen bond to the free oxygen atoms of the oxalate ligand of the complex [Sn(H2OCl3(C2O4]− anion. Neighbouring stannate(IV anions are linked through O—H...O hydrogen bonds involving the water molecule and the two non-coordinating oxalate oxygen atoms. In combination with additional N—H...Cl hydrogen bonds between cations and anions, a three-dimensional network is spanned.

  20. Europium-doped barium bromide iodide

    Energy Technology Data Exchange (ETDEWEB)

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  1. Barium dithionate as an EPR dosemeter.

    Science.gov (United States)

    Baran, M P; Bugay, O A; Kolesnik, S P; Maksimenko, V M; Teslenko, V V; Petrenko, T L; Desrosiers, M F

    2006-01-01

    Electron paramagnetic resonance (EPR) dosimetry is growing in popularity and this success has encouraged the search for other dosimetric materials. Previous studies of gamma-irradiated barium dithionate (BaS(2)O(6) x 2H(2)O) have shown promise for its use as a radiation dosemeter. This work studies in greater detail several essential attributes of the system. Special attention has been directed to the study of EPR response dependences on microwave power, irradiation temperature, minimum detectable dose and post-irradiation stability. PMID:16565205

  2. Scattering lengths of calcium and barium isotopes

    OpenAIRE

    Dammalapati, U.; Willmann, L.; Knoop, S.

    2011-01-01

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba), in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed 40Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that ...

  3. Barium enema findings of milk allergy in infants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyoung Ju; Kim, Mi Jeong; Lee, Hee Jung [Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2006-09-15

    We wanted to evaluate the barium enema findings of milk allergy in infants. Retrospective evaluation of the plain abdominal radiography and barium enema findings was performed in fifteen young infants suffering with milk allergy. The presence of gaseous distension, rectal gas, paralytic ileus and mechanical obstruction was evaluated on the plain radiography. The presence of spasm, a transitional zone, a reversed rectosigmoid index and mucosal irregularity was analyzed on the barium enema; the presence of barium retention was also evaluated on 24-hour-delayed plain radiography. Paralytic ileus was the most common finding on the plain radiography (93%). On the barium enema, continuous spasm of the colon, ranging from the rectum to the descending colon, was revealed in ten infants (67%). A transitional zone was observed in one infant and a reversed rectosigmoid index was revealed in four. Mucosal irregularity was observed in two infants. Barium retention was demonstrated in 11 of fifteen cases: throughout the entire colon (n = 3), from the rectum to the descending colon (n = 7), and up to the transverse colon (n = 1). The most common barium enema finding of milk allergy in infants was spasm of the distal colon. The other findings were a transitional zone, a reversed rectosigmoid index, mucosal irregularity and barium retention.

  4. Barium and radium migration in unconsolidated Canadian geological materials

    International Nuclear Information System (INIS)

    This report describes the results of laboratory studies on the distribution coefficients of radium and barium in samples of unconsolidated geologic materials. Graphs of Ksub(d) versus solution concentration for the respective elements showed constant Ksub(d) values in the low concentration range suggesting that, at low concentrations, a distribution coefficient is a valid means of representing the geochemical reactions of both barium and radium. The Ksub(d) values for barium range between 60 and 3500 ml/g. The values appear to be influenced by the amount of barium occurring naturally in the soil materials and thus there is little possiblility of using barium as an analog of radium in laboratory experiments. The Ksub(d) values of radium vary from 50 to 1000 ml/g indicating that a wide range of geological materials have a substantial capacity to retard the migration of radium

  5. Effect of TiO2 on the optical, structural and crystallization behavior of barium borate glasses

    Science.gov (United States)

    Marzouk, M. A.; ElBatal, F. H.; ElBatal, H. A.

    2016-07-01

    Collective characterizations of prepared binary barium borate glass (50 mol % BaO - 50 mol % B2O3) together with samples containing increasing added TiO2 contents (5% → 30%) were carried out by optical and FT infrared absorption measurements. FT infrared and X-ray diffraction analysis were done for heat treated glass - ceramic derivatives prepared through two step regime process. Optical spectra of the glasses reveal the presence of titanium ions mainly in the tetravalent state imparting additional UV band beside strong UV absorption due to trace iron impurity. IR spectral studies indicate the presence of triangular and tetrahedral borate groups through the modification of BaO to some BO3 to BO4 groups beside the presence of titanium ions as interfering or overlapping TiO4 or Bsbnd Osbnd Ti groupings in the glassy network. Crystalline X-ray diffraction results indicate the separation of crystalline barium borate of the composition (2BaO.5 B2O3) as a main constituent together with some crystalline alkali titanates confirming the role of TiO2 of both as nucleating agent beside acting as structural forming through reaction with alkali oxides to form crystalline titanates. The optical band gap values reveal progressive decrease and increase of Urbach energy with TiO2 content and the same for the refractive index values and all these parameters are correlated with the proposed changes in the glass constitution with the introduction of TiO2. The additional thermal expansion measurements indicate the peculiar characteristic negative expansion up to 300 °C and after which an increase in the coefficient of thermal expansion is identified with the increase in temperature. The thermal parameters are also correlated with the modification of the glass structure by the introduction of titanium ions.

  6. Barium appendicitis: A single institution review in Japan

    Science.gov (United States)

    Katagiri, Hideki; Lefor, Alan Kawarai; Kubota, Tadao; Mizokami, Ken

    2016-01-01

    AIM To review clinical experience with barium appendicitis at a single institution. METHODS A retrospective review of patients admitted with a diagnosis of acute appendicitis, from January 1, 2013 to December 31, 2015 was performed. Age, gender, computed tomography (CT) scan findings if available, past history of barium studies, pathology, and the presence of perforation or the development of complications were reviewed. If the CT scan revealed high density material in the appendix, the maximum CT scan radiodensity of the material is measured in Hounsfield units (HU). Barium appendicitis is defined as: (1) patients diagnosed with acute appendicitis; (2) the patient has a history of a prior barium study; and (3) the CT scan shows high density material in the appendix. Patients who meet all three criteria are considered to have barium appendicitis. RESULTS In total, 396 patients were admitted with the diagnosis of acute appendicitis in the study period. Of these, 12 patients (3.0%) met the definition of barium appendicitis. Of these 12 patients, the median CT scan radiodensity of material in the appendix was 10000.8 HU, ranging from 3066 to 23423 HU (± 6288.2). In contrast, the median CT scan radiodensity of fecaliths in the appendix, excluding patients with barium appendicitis, was 393.1 HU, ranging from 98 to 2151 HU (± 382.0). The CT scan radiodensity of material in the appendices of patients with barium appendicitis was significantly higher than in patients with nonbarium fecaliths (P < 0.01). CONCLUSION Barium appendicitis is not rare in Japan. Measurement of the CT scan radiodensity of material in the appendix may differentiate barium appendicitis from routine appendicitis.

  7. The Lakes and Seas of Titan

    Science.gov (United States)

    Hayes, Alexander G.

    2016-06-01

    Analogous to Earth's water cycle, Titan's methane-based hydrologic cycle supports standing bodies of liquid and drives processes that result in common morphologic features including dunes, channels, lakes, and seas. Like lakes on Earth and early Mars, Titan's lakes and seas preserve a record of its climate and surface evolution. Unlike on Earth, the volume of liquid exposed on Titan's surface is only a small fraction of the atmospheric reservoir. The volume and bulk composition of the seas can constrain the age and nature of atmospheric methane, as well as its interaction with surface reservoirs. Similarly, the morphology of lacustrine basins chronicles the history of the polar landscape over multiple temporal and spatial scales. The distribution of trace species, such as noble gases and higher-order hydrocarbons and nitriles, can address Titan's origin and the potential for both prebiotic and biotic processes. Accordingly, Titan's lakes and seas represent a compelling target for exploration.

  8. Interaction of Titan's ionosphere with Saturn's magnetosphere.

    Science.gov (United States)

    Coates, Andrew J

    2009-02-28

    Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10000amu at 950km altitude. PMID:19073464

  9. High resolution studies of barium Rydberg states

    International Nuclear Information System (INIS)

    The subtle structure of Rydberg states of barium with orbital angular momentum 0, 1, 2 and 3 is investigated. Some aspects of atomic theory for a configuration with two valence electrons are reviewed. The Multi Channel Quantum Defect Theory (MQDT) is concisely introduced as a convenient way to describe interactions between Rydberg series. Three high-resolution UV studies are presented. The first two, presenting results on a transition in indium and europium serve as an illustration of the frequency doubling technique. The third study is of hyperfine structure and isotope shifts in low-lying p states in Sr and Ba. An extensive study of the 6snp and 6snf Rydberg states of barium is presented with particular emphasis on the 6snf states. It is shown that the level structure cannot be fully explained with the model introduced earlier. Rather an effective two-body spin-orbit interaction has to be introduced to account for the observed splittings, illustrating that high resolution studies on Rydberg states offer an unique opportunity to determine the importance of such effects. Finally, the 6sns and 6snd series are considered. The hyperfine induced isotope shift in the simple excitation spectra to 6sns 1S0 is discussed and attention is paid to series perturbers. It is shown that level mixing parameters can easily be extracted from the experimental data. (Auth.)

  10. NANOSCALE BARIUM HYDROSILICATES: CHOOSING THE SYNTHESIS TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    GRISHINA Anna Nikolaevna

    2013-08-01

    Full Text Available Cement concretes are the most used materials in modern civil engineering. Due to that such materials draw great attention both in the Russian Federation and abroad. The possibility to enhance the manufacturability and operational properties of concretes results in significant reduction of overall operating costs. Many enhancement methods have been elaborated. Among them there is one based on introduction of calcium hydrosilicates into construction composition. The authors set up a hypothesis that similarity between properties and structures of different hydrosilicates (for example, alkaline earth metals and metals of the second group will provide similar increased operational characteristics. The specialists of Research and Educational Center «Nanotechnology» are developing cement composites nanomodification methods which include introduction of nanodimensional barium hydrosilicates particles. The synthesis of barium hydrosilicates particles can be done with the use of many technologies, different by energy consumption or performing complexity. Taking into account both these factors, one can assume that low-temperature sol-gel synthesis from diluted water solutions is the proper technology. The present paper shows that this assumption is correct. The selection of certain technology is made by the means of multiobjective optimization, which is in turn is performed by the means of linear scalarization. This method, while not always giving the Pareto optimal solutions, can be easily implemented. The particle size distribution is taken into consideration during selection of objectives and weights. It is shown that selected technology allows manufacturing nanoparticles with median size about 30 nm.

  11. Coprecipitation of europium with barium sulphate

    International Nuclear Information System (INIS)

    The distribution behaviour of the trivalent europium ion at a micro-component scale, between barium sulphate and aqueous solution, was studied at ambient temperature. Experiments were carried out using radioactive tracers. Results indicate an enrichment of the micro component in the solid phase relative to the solution. The effects of the concentrations of the micro and macro-elements on the coprecipitation have been examined. Europium distribution coefficient DEu increases from 1.1 ± 0.2 to 3.2 ± 0.4 when initial europium concentration decreases from more than 17 x 10-5 to 1.4 x 10-5 M, in sulphuric media with SO42- in excess or CBa2+/CSO42- Eu. The coprecipitation of europium with barium sulphate as a heterovalent solid-solution is described by heterogeneous model obeying the Doerner and Hoskins logarithmic partition law. The weaker partition coefficients lower than unity (λ = 0.25 when CEu(III) ∼ 1.4 x 10-5 M and λ = 0.13 when CBa2+/CSO42- -5 ≤ CEu(III) = 153.5 x 10-5 M) lead to crystals increasingly enriched in the trace element. (orig.)

  12. Titan as the Abode of Life

    Science.gov (United States)

    Mckay, Christopher P.

    2016-01-01

    Titan is the only world we know other than Earth that has a liquid on its surface. It has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in the atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the Universe is full of diverse and wondrous life forms.

  13. This is Commercial Titan, Inc

    Science.gov (United States)

    van Rensselaer, F. L.; Slovikoski, R. D.; Abels, T. C.

    1989-10-01

    Out of a quarter-century heritage of eminently successful expendable launch vehicle history with the U.S government, a commercial launch services enterprise which challenges the corporation as well as the competition has been launched within the Martin Marietta Corporation. This paper is an inside look at the philosophy, structure, and success of the new subsidiary, Commercial Titan, Inc., which is taking on its U.S. and foreign rocket-making competitors to win a share of the international communication satellite market as well as the U.S. government commercial launch services market.

  14. Aerosol growth in Titan's ionosphere.

    Science.gov (United States)

    Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

    2013-02-19

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

  15. Titan's Obliquity as evidence for a subsurface ocean?

    OpenAIRE

    Baland, Rose-Marie; Van Hoolst, Tim; Yseboodt, Marie; Karatekin, Ozgur

    2011-01-01

    On the basis of gravity and radar observations with the Cassini spacecraft, the moment of inertia of Titan and the orientation of Titan's rotation axis have been estimated in recent studies. According to the observed orientation, Titan is close to the Cassini state. However, the observed obliquity is inconsistent with the estimate of the moment of inertia for an entirely solid Titan occupying the Cassini state. We propose a new Cassini state model for Titan in which we assume the presence of ...

  16. Strengthening mechanism of steels treated by barium-bearing alloys

    Institute of Scientific and Technical Information of China (English)

    Zhouhua Jiang; Yang Liu

    2008-01-01

    The deoxidation, desulfurization, dephosphorization, microstructure, and mechanical properties of steels treated by barium-bearing alloys were investigated in laboratory and by industrial tests. The results show that barium takes part in the deoxidation reaction at the beginning of the experiments, generating oxide and sulfide compound inclusions, which easily float up from the molten steel, leading to the rapid reduction of total oxygen content to a very low level. The desulfurization and dephosphorization capabilities of calcium-bearing alloys increase with the addition of barium. The results of OM and SEM observations and mechanical property tests show that the structure of the steel treated by barium-bearing alloys is refined remarkably, the iamellar thickness of pearlitic structure decreases, and the pearlitic morphology shows clustering distribution. Less barium exists in steel substrate and the enrichment of barium-bearing precipitated phase mostly occurs in grain boundary and phase boundary, which can prevent the movement of grain boundary and dislocation during the heat treatment and the deformation processes. Therefore, the strength and toughness of barium-treated steels are improved by the effect of grain-boundary strengthening and nail-prick dislocation.

  17. Designed microstructures in textured barium hexaferrite

    Science.gov (United States)

    Hovis, David Brian

    It is a fundamental principle of materials science that the microstructure of a material defines its properties and ultimately its performance for a given application. A prime example of this can be found in the large conch shell Strombus gigas, which has an intricate microstructure extending across five distinct length scales. This microstructure gives extraordinary damage tolerance to the shell. The structure of Strombus gigas cannot be replicated in a modern engineering ceramic with any existing processing technique, so new processing techniques must be developed to apply this structure to a model material. Barium hexaferrite was chosen as a model material to create microstructures reminiscent of Strombus gigas and evaluate its structure-property relations. This work describes novel processing methods to produce textured barium hexaferrite with no coupling between the sample geometry and the texture direction. This technique, combining magnetic field-assisted gelcasting with templated grain growth, also allows multilayer samples to be fabricated with different texture directions in adjacent layers. The effects of adding either B2O3 or excess BaCO 3 on the densification and grain growth of barium hexaferrite was studied. The texture produced using this technique was assessed using orientation imaging microscopy (OIM) at Oak Ridge National Laboratory. These measurements showed peak textures as high as 60 MRD and sharp interfaces between layers cast with different texture directions. The effect of oxygen on the quality of gelcasting is also discussed, and it is shown that with proper mold design, it is possible to gelcast multiple layers with differing texture directions without delamination. Monolithic and multilayer samples were produced and tested in four point bending to measure the strength and work of fracture. Modulus measurements, made with the ultrasonic pulse-echo technique, show clear signs of microcracking in both the isotropic and textured samples

  18. Neutral Chemistry in Titan's Ionospheric Simulated Conditions

    Science.gov (United States)

    Dubois, David; Carrasco, Nathalie; Petrucciani, Marie; Tigrine, Sarah; Vettier, Ludovic

    2016-10-01

    Titan's atmospheric gas phase chemistry leading to the formation of organic aerosols can be simulated in laboratory experiments. Typically, plasma reactors can be used to achieve Titan-like conditions. Such a discharge induces dissociation and ionization processes to the N2-CH4 mixture by electron impact. This faithfully reproduces the electron energy range of magnetospheric electrons entering Titan's atmosphere and can also approximate the solar UV input at Titan's ionosphere. In this context, it is deemed necessary to apply and exploit such a technique in order to better understand the chemical reactivity occurring in Titan-like conditions.In the present work, we use the PAMPRE cold dusty plasma experiment with an N2-CH4 gaseous mixture under controlled pressure and gas influx, hence, emphasizing on the gas phase which we know is key to the formation of aerosols on Titan. Besides, an internal cryogenic trap has been developed to accumulate the gas products during their formation and facilitate their detection. These products are identified and quantified by in situ mass spectroscopy and Fourier-Transform Infrared Spectroscopy. We present here results from this experiment in two experimental conditions: 90-10% and 99-1% N2-CH4 mixing ratios respectively. We use a quantitative approach on nitriles and polycyclic aromatic hydrocarbons.Key organic compounds reacting with each other are thus detected and quantified in order to better follow the chemistry occuring in the gas phase of Titan-like conditions. Indeed, these species acting as precursors to the solid phase are assumed to be relevant in the formation of Titan's organic aerosols. These organic aerosols are what make up Titan's hazy atmosphere.

  19. Chemical composition of Eu2+ luminescence in the barium hexaaluminates

    International Nuclear Information System (INIS)

    This paper consists of two parts. In the first part the chemical composition of two kinds of barium hexaaluminate (one poor and one rich in barium) is explained using the local electroneutrality concept. In the second part a reinvestigation of the Eu2+ luminescence in these compounds is reported. The emission spectrum of each of the two compounds shows a blue and a green emission bank. The blue emission bank is ascribed to Eu2+ ions at barium sites, whereas the green emission band is identified with Eu2+ ions incorporated at aluminum sites within spinel blocks of the structure

  20. Barium concentration in grain of Aegilops and Triticum species

    Directory of Open Access Journals (Sweden)

    Denčić Srbislav S.

    2015-01-01

    Full Text Available The aim of this study was to evaluate the concentration of barium in grain of various Aegilops and Triticum species with different genomes. The studied species differed significantly with respect to the concentration of barium. The grain of wild diploid Aegilops speltoides, the donor of B genome, contained significantly higher Ba concentration than all other analyzed genotypes. Wild and cultivated tetraploid wheats (Triticum diciccoides, Triticum dicoccon, Triticum turgidum and Triticum durum had the lowest Ba concentration in grain. The modern cultivated hexaploid varieties presented substantial variation in grain concentration of barium. The highest Ba concentration (3.42 mg/kg occurred in Serbian winter wheat variety Panonnia.

  1. The greenhouse and antigreenhouse effects on Titan

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1991-01-01

    The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

  2. Titan's organic chemistry: Results of simulation experiments

    Science.gov (United States)

    Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

    1992-01-01

    Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

  3. Titan the earth-like moon

    CERN Document Server

    Coustenis, Athena

    1999-01-01

    This is the first book to deal with Titan, one of the most mysterious bodies in the solar system. The largest satellite of the giant planet Saturn, Titan is itself larger than the planet Mercury, and is unique in being the only known moon with a thick atmosphere. In addition, its atmosphere bears a startling resemblance to the Earth's, but is much colder.The American and European space agencies, NASA and ESA, have recently combined efforts to send a huge robot spacecraft to orbit Saturn and land on Titan. This book provides the background to this, the greatest deep space venture of our time, a

  4. Structure of barium sodium trimetaphosphate trihydrate

    Energy Technology Data Exchange (ETDEWEB)

    Averbuch-Pouchot, M.T.; Durif, A.

    1987-03-15

    BaNaP/sub 3/O/sub 9/ . 3H/sub 2/O, M/sub r/=451.29, triclinic, Panti 1, a=7.067(3), b=9.071(3), c=9.906(4) A, ..cap alpha..=116.46(5), ..beta..=95.97(5), ..gamma..=74.03(5)/sup 0/, V=546.4 A/sup 3/, Z=2, D/sub m/ not measured, D/sub x/=2.743 Mg m/sup -3/, lambda(Mo K..cap alpha..)=0.7107 A, ..mu..=4.28 mm/sup -1/, F(000)=428, T=293 K, R=0.028 for 3775 independent reflexions. The P/sub 3/O/sub 9/ ring anions and the water molecules build up a three-dimensional network through hydrogen bonds. Inside this network barium and sodium have respectively nine- and sevenfold coordinations.

  5. Analysis of europium doped luminescent barium thioaluminate

    Institute of Scientific and Technical Information of China (English)

    张东璞; 喻志农; 薛唯; 章婷; 丁瞾; 王武育

    2010-01-01

    Europium-doped barium thioaluminate sputtering target was synthesized by powder sintering method and thin film was deposited by radio frequency(RF) sputtering.X-ray diffractometer(XRD) pattern indicated that the main compound of the target was BaAl4S7.Oxygen was the main impurity which led to the formation of BaAl2O4.It was shown that both BaAl4S7 and BaAl2S4 were contained in the as-grown thin films and a 471.7 nm emission peak in the PL spectra appeared due to a combination of BaAl4S7:Eu2+ and BaAl2S4:Eu2...

  6. Chemical abundance analysis of 19 barium stars

    CERN Document Server

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  7. A novel barium polymeric membrane sensor for selective determination of barium and sulphate ions based on the complex ion associate barium(II)-Rose Bengal as neutral ionophore

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A.M. [Genetic Engineering and Biotechnology Research Institute (GEBRI), Minufiya University, Sadat City (Egypt); El-Shahawi, M.S. [Chemistry Department, Faculty of Science at Damiatta, Mansoura University, Damiatta, Dumyat 34517 (Egypt)]. E-mail: mohammad_el_shahawi@yahoo.co.uk; Abdel-Azeem, M. [Chemistry Department, Faculty of Science at Damiatta, Mansoura University, Damiatta, Dumyat 34517 (Egypt)

    2006-01-12

    A simple, long life, rapid response and sensitive barium(II)-PVC membrane sensor that typically follows Nernstian behavior has been developed for the assay of barium(II) ions. The developed sensor has been made by incorporating the complex ion associate of barium(II)-Rose Bengal (Ba-RB) as an ionophore into a plasticized PVC matrix. The sensor is stable and exhibited fast potential response of 20 s and gave a good linear response with a Nernstian slope of 28.5 {+-} 0.4 mV/decade of activity within the concentration range 5 x 10{sup -5} to 10{sup -1} M over a wide range of pH 4.5-10.0 for barium(II) ions. The developed sensor showed comparatively good selectivity for barium(II) ions with respect to other alkali, alkaline earth, transition and heavy metal ions. The plasticizer o-nitrophenyloctyl ether controlled significantly the calibration slope and the lifetime of the fabricated sensor. The proposed sensor was used successfully for the analysis of barium(II) ions in wastewater samples and in lithophone pigment with excellent recovery percentages in the range 98.9-99.8 {+-} 1.6%. The determination of sulphate in fresh and potable water samples with the developed sensor has been also achieved successfully. The described sensor provides a reliable means with good correlation with the data obtained by atomic absorption spectrometry (AAS) and other spectrophotometric methods for the analysis of trace amounts of barium(II) and/or sulphate ions in different matrices.

  8. A novel barium polymeric membrane sensor for selective determination of barium and sulphate ions based on the complex ion associate barium(II)-Rose Bengal as neutral ionophore

    International Nuclear Information System (INIS)

    A simple, long life, rapid response and sensitive barium(II)-PVC membrane sensor that typically follows Nernstian behavior has been developed for the assay of barium(II) ions. The developed sensor has been made by incorporating the complex ion associate of barium(II)-Rose Bengal (Ba-RB) as an ionophore into a plasticized PVC matrix. The sensor is stable and exhibited fast potential response of 20 s and gave a good linear response with a Nernstian slope of 28.5 ± 0.4 mV/decade of activity within the concentration range 5 x 10-5 to 10-1 M over a wide range of pH 4.5-10.0 for barium(II) ions. The developed sensor showed comparatively good selectivity for barium(II) ions with respect to other alkali, alkaline earth, transition and heavy metal ions. The plasticizer o-nitrophenyloctyl ether controlled significantly the calibration slope and the lifetime of the fabricated sensor. The proposed sensor was used successfully for the analysis of barium(II) ions in wastewater samples and in lithophone pigment with excellent recovery percentages in the range 98.9-99.8 ± 1.6%. The determination of sulphate in fresh and potable water samples with the developed sensor has been also achieved successfully. The described sensor provides a reliable means with good correlation with the data obtained by atomic absorption spectrometry (AAS) and other spectrophotometric methods for the analysis of trace amounts of barium(II) and/or sulphate ions in different matrices

  9. The Karlsruhe 4π barium fluoride detector

    International Nuclear Information System (INIS)

    A new experimental approach has been implemented for accurate measurements of neutron capture cross sections in the energy range from 5 to 200 keV. The Karlsruhe 4π Barium Fluoride Detector consists of 42 crystals shaped as hexagonal and pentagonal truncated pyramids forming a spherical shell with 10 cm inner radius and 15 cm thickness. All crystals are supplied with reflector and photomultiplier, thus representing independent gamma-ray detectors. Each detector module covers the same solid angle with respect to a gamma-ray source located in the centre. The energy resolution of the 4π detector is 14% at 662 keV and 7% at 2.5 MeV gamma-ray energy, the overall time reslution is 500 ps and the peak efficiency 90% at 1 MeV. The detector allows to register capture cascades with 95% probability above a threshold energy of 2.5 MeV in the sum energy spectrum. Neutrons are produced via the 7Li(p,n)7Be reaction using the pulsed proton beam of a Van de Graaff accelerator. The neutron spectrum can be taylored according to the experimental requirements in an energy range from 5 to 200 keV by choosing appropriate proton energies. A collimated neutron beam is passing through the detector and hits the sample in the centre. The energy of captured neutrons is determined via time of flight, the primary flight path being 77 cm. The combination of short primary flight path, a 10 cm inner radius of the spherical BaF2 shell, and the low capture cross section of barium allows to discriminate background due to capture of sample scattered neutrons in the scintillator by time of flight, leaving part of the neutron energy range completely undisturbed. (orig./HSI)

  10. Titan Mare Explorer (TiME) : A Discovery Mission to Titan's Hydrocarbon Seas

    Science.gov (United States)

    Lorenz, Ralph D.; Stofan, Ellen; T. H. E. Time Team

    2010-05-01

    The discovery of lakes in Titan's high latitudes confirmed the expectation that liquid hydrocarbons exist on the surface of the haze-shrouded moon. The lakes fill through drainage of subsurface runoff and/or intersection with the subsurface alkanofer, providing the first evidence for an active condensable-liquid hydrological cycle on another planetary body. The unique nature of Titan's methane cycle, along with the prebiotic chemistry and implications for habitability of Titan's lakes, make the lakes of the highest scientific priority for in situ investigation. The Titan Mare Explorer mission is an ASRG (Advanced Stirling Radioisotope Generator)-powered mission to a lake on Titan. The mission would be the first exploration of a planetary sea beyond Earth, would demonstrate the ASRG both in deep space and a non-terrestrial atmosphere environment, and pioneer low-cost outer planet missions. The scientific objectives of the mission are to: determine the chemistry of a Titan lake to constrain Titan's methane cycle; determine the depth of a Titan lake; characterize physical properties of liquids; determine how the local meteorology over the lakes ties to the global cycling of methane; and analyze the morphology of lake surfaces, and if possible, shorelines, in order to constrain the kinetics of liquids and better understand the origin and evolution of Titan lakes. The focused scientific goals, combined with the new ASRG technology and the unique mission design, allows for a new class of mission at much lower cost than previous outer planet exploration has required.

  11. TSSM: The in situ exploration of Titan

    Science.gov (United States)

    Coustenis, A.; Lunine, J. I.; Lebreton, J. P.; Matson, D.; Reh, K.; Beauchamp, P.; Erd, C.

    2008-09-01

    The Titan Saturn System Mission (TSSM) mission was born when NASA and ESA decided to collaborate on two missions independently selected by each agency: the Titan and Enceladus mission (TandEM), and Titan Explorer, a 2007 Flagship study. TandEM, the Titan and Enceladus mission, was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call. The mission concept is to perform remote and in situ investigations of Titan primarily, but also of Enceladus and Saturn's magentosphere. The two satellites are tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TSSM will study Titan as a system, including its upper atmosphere, the interactions with the magnetosphere, the neutral atmosphere, surface, interior, origin and evolution, as well as the astrobiological potential of Titan. It is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini- Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time for Titan, several close flybys of Enceladus). One overarching goal of the TSSM mission is to explore in situ the atmosphere and surface of Titan. In the current mission architecture, TSSM consists of an orbiter (under NASA's responsibility) with a large host of instruments which would perform several Enceladus and Titan flybys before stabilizing in an orbit around Titan alone, therein delivering in situ elements (a Montgolfière, or hot air balloon, and a probe/lander). The latter are being studied by ESA. The balloon will circumnavigate Titan above the equator at an altitude of about 10 km for several months. The

  12. Titan's Atmospheric Dynamics and Meteorology

    Science.gov (United States)

    Flasar, F. M.; Baines, K. H.; Bird, M. K.; Tokano, T.; West, R. A.

    2008-01-01

    Titan, after Venus, is the second example of an atmosphere with a global cyclostrophic circulation in the solar system, but a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10degS, indicate that the zonal winds are generally in the sense of the satellites rotation. They become cyclostrophic approx. 35 km above the surface and generally increase with altitude, with the exception of a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from the temperature field retrieved from Cassini measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds at mid northern latitudes of 190 ms-' near 300 km. Above this level, the vortex decays. Curiously, the zonal winds and temperatures are symmetric about a pole that is offset from the surface pole by approx.4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the solar equator. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures in the north polar region near 400 km and the enhanced concentration of several organic molecules suggests subsidence there during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50degN. Titan's winter polar vortex appears to share many of the same characteristics of winter vortices on Earth-the ozone holes. Global mapping of temperatures, winds, and composition in he troposphere, by contrast, is incomplete. The few suitable discrete clouds that have bee found for tracking indicate smaller velocities than aloft, consistent with the

  13. A NOVEL HYDROTHERMAL SYNTHESIS METHOD FOR BARIUM FERRITE

    Institute of Scientific and Technical Information of China (English)

    Kang Li; Hongchen Gu; Qun Wei

    2004-01-01

    In the present work, fine barium ferrite powder has been synthesized through a one-step hydrothermal process in an autoclave at [OH-]/[Cl-] ratio of 2:1 in the temperature range from 180 to 260 ℃ using barium chloride (BaCl2), ferrous chloride (FeCl2) and potassium nitrate (KNO3) as the starting materials. Both particle size and saturation magnetization (Ms) increase with increasing hydrothermal reaction temperature, while the intrinsic coercivity (iHc) peaks at 685 Oe at 230 ℃. Morphology progress from the barium ferrite precursor particles to the barium hexaferrite particles has been monitored with increasing hydrothermal reaction time at 230 ℃ in the autoclave.

  14. Upper gastrointestinal barium evaluation of duodenal pathology: A pictorial review

    Institute of Scientific and Technical Information of China (English)

    Pankaj; Gupta; Uma; Debi; Saroj; Kant; Sinha; Kaushal; Kishor

    2014-01-01

    Like other parts of the gastrointestinal tract(GIT), duodenum is subject to a variety of lesions both congenital and acquired. However, unlike other parts of the GIT viz. esophagus, rest of the small intestine and large intestine, barium evaluation of duodenal lesions is technically more challenging and hence not frequently reported. With significant advances in computed tomography technology, a thorough evaluation including intraluminal, mural and extramural is feasible in a single non-invasive examination. Notwithstanding, barium evaluation still remains the initial and sometimes the only imaging study in several parts of the world. Hence,a thorough acquaintance with the morphology of various duodenal lesions on upper gastrointestinal barium examination is essential in guiding further evaluation. We reviewed our experience with various common and uncommon barium findings in duodenal abnormalities.

  15. Peritonite por bário Barium peritonitis

    Directory of Open Access Journals (Sweden)

    Gerson Alves Pereira Júnior

    1999-10-01

    Full Text Available We report a case of a 49 years-old man who underwent a barium meal examination for an epigastric pain. A perforated gastric ulcer with barium extravasation into peritoneal cavity was seen on X-rays. During an emergency laparotomy, a perforated pyloric ulcer was noted, along with barium contamination in the peritoneal cavity. The ulcer was closed with an omental patch and an extensive peritoneal lavage with saline was performed. During the postoperative period, the patient developed signs of peritonitis and underwent a new laparotomy was at the 9th day showing a subfrenic abscess with a large barium contamination. The patient presented septic shock and multiple organ failure. dying on the 21th day.

  16. The tide in the seas of Titan

    Science.gov (United States)

    Sagan, C.; Dermott, S. F.

    1982-01-01

    The parameters of the tides in the near-global ocean that may exist on Titan are assessed. A formula for the difference between the maximum heights of the oceanic and body tides is used to determine that the amplitude of the apparent, near-stationary, oceanic tide on Titan is greater than about 100 m. The effects of tidal dissipation are evaluated, showing that the amplitude of the tide will vary by nine percent over its 15.95-day period. The observed eccentricity of Titan's orbit is used to establish limits on the satellite's surface topography and oceanic depths. It is concluded that either Titan is covered by a near-global methane ocean over 400 m deep, or that there is no methane ocean at all. Reflectivity measurements can decide between these alternatives.

  17. Cyanide Soap? Dissolved material in Titan's Seas

    Science.gov (United States)

    Lorenz, R. D.; Lunine, J. I.; Neish, C. D.

    2011-10-01

    Although it is evident that Titan's lakes and seas are dominated by ethane, methane, nitrogen, and (in some models) propane, there is divergence on the predicted relative abundance of minor constituents such as nitriles and C-4 alkanes. Nitriles such as hydrogen cyanide and acetonitrile, which have a significant dipole moment, may have a disproportionate influence on the dielectric properties of Titan seas and may act to solvate polar molecules such as water ice. The hypothesis is offered that such salvation may act to enhance the otherwise negligible solubility of water ice bedrock in liquid hydrocarbons. Such enhanced solubility may permit solution erosion as a formation mechanism for the widespread pits and apparently karstic lakes on Titan. Prospects for testing this hypothesis in the laboratory, and with measurements on Titan, will be discussed.

  18. Parallel contingency statistics with Titan.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, David C.; Pebay, Philippe Pierre

    2009-09-01

    This report summarizes existing statistical engines in VTK/Titan and presents the recently parallelized contingency statistics engine. It is a sequel to [PT08] and [BPRT09] which studied the parallel descriptive, correlative, multi-correlative, and principal component analysis engines. The ease of use of this new parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; however, the very nature of contingency tables prevent this new engine from exhibiting optimal parallel speed-up as the aforementioned engines do. This report therefore discusses the design trade-offs we made and study performance with up to 200 processors.

  19. Cassini UVIS observations of Titan nightglow spectra

    OpenAIRE

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; Mcclintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-01-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluor...

  20. Lifetime Measurement for 6snp Rydberg States of Barium

    Institute of Scientific and Technical Information of China (English)

    SHEN Li; WANG Lei; YANG Hai-Feng; LIU Xiao-Jun; LIU Hong-Ping

    2011-01-01

    @@ We present a simple and efficient method for measuring the atomic lifetimes in order of tens of microseconds and demonstrate it in the lifetime determination of barium Rydberg states.This method extracts the lifetime information from the time-of-flight spectrum directly, which is much more efficient than other methods such as the time-delayed field ionization and the traditional laser induced fluorescence.The lifetimes determined with our method for barium Rydberg 6snp(n=37-59)series are well coincident with the values deduced from the absolute oscillator strengths of barium which were given in the literature [J.Phys.B 14(1981)4489, 29(1996)655]on experiments.%We present a simple and efficient method for measuring the atomic lifetimes in order of tens of microseconds and demonstrate it in the lifetime determination of barium Rydberg states. This method extracts the lifetime information from the time-of-flight spectrum directly, which is much more efficient than other methods such as the time-delayed field ionization and the traditional laser induced fluorescence. The lifetimes determined with our method for barium Rydberg 6snp (n=37-59) series are well coincident with the values deduced from the absolute oscillator strengths of barium which were given in the literature [J. Phys. B 14 (1981) 4489, 29 (1996) 655] onexperiments.

  1. The Chemical Evolution of Titan's Atmosphere

    Science.gov (United States)

    Kaiser, Ralf I.

    2010-11-01

    Astrochemistry or Astrochemical Dynamics presents a newly emerging, interdisciplinary and innovative field comprising scientists in chemistry, physics, biology, astronomy, and planetary chemistry. The prime directive of Astrochemical Dynamics is to understand the origin and chemical evolution of the interstellar medium and of our Solar System. Here, the arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and thick atmosphere - in 2004 opened up a new chapter in the history of Solar System exploration. Titan's most prominent optically visible features are the aerosol-based haze layers, which give Titan its orange-brownish color. However, the underlying chemical processes, which initiate the haze formation, have been the least understood to date. This talk reviews recent laboratory studies on the role of polyacetylenes (polyynes) and (hetero)aromatic molecules like the phenyl radical, benzene, and pyridine in the formation of Titan's organic haze layers utilizing crossed molecular beam experiments. Those investigations provide key concepts on the formation mechanisms of unsaturated hydrocarbon molecules - in particular polyynes and aromatic compounds - together with their hydrogen deficient precursors from the "bottom up" in the atmosphere of Saturn's moon Titan. A brief outline to future research directions tackling also the heterogeneous chemistry on Titan and in hydrocarbon-rich atmospheres in the outer Solar System in general will also be presented.

  2. Exploring the Seas of Titan: The Titan Mare Explorer (TiME) Mission

    Science.gov (United States)

    Stofan, E. R.; Lunine, J. I.; Lorenz, R. D.; Aharonson, O.; Bierhaus, E.; Clark, B.; Griffith, C.; Harri, A.-M.; Karkoschka, E.; Kirk, R.; Kantsiper, B.; Mahaffy, P.; Newman, C.; Ravine, M.; Trainer, M.; Waite, H.; Zarnecki, J.

    2010-03-01

    The Titan Mare Explorer (TiME) is a Discovery-class mission that would constrain Titan’s active methane cycle as well as its intriguing prebiotic organic chemistry by providing in situ measurements from the surface of a Titan sea.

  3. Constraining the Role of Seas and Lakes in Titan's Climate: The Titan Mare Explorer Mission

    Science.gov (United States)

    Stofan, E. R.; Lunine, J. I.; Lorenz, R. D.; Aharonson, O.; Bierhaus, E.; Clark, B.; Griffith, C.; Harri, A. M.; Karkoschka, E.; Kirk, R.; Mahaffy, P.; Newman, C.; Ravine, M.; Trainer, M.; Turtle, E.; Waite, H.; Yelland, M.; Zarnecki, J.; Hayes, A.

    2012-06-01

    Lakes and seas on Titan provide the first evidence for an extraterrestrial active liquid cycle and play a key role in its climate. Constraints on Titan's methane cycle, analogous to Earth’s hydrologic cycle, can be made through in situ measurements.

  4. Dissolution on Titan and on Earth: Towards the age of Titan's karstic landscapes

    CERN Document Server

    Cornet, Thomas; Bahers, Tangui Le; Bourgeois, Olivier; Fleurant, Cyril; Mouélic, Stéphane Le; Altobelli, Nicolas

    2015-01-01

    Titan's polar surface is dotted with hundreds of lacustrine depressions. Based on the hypothesis that they are karstic in origin, we aim at determining the efficiency of surface dissolution as a landshaping process on Titan, in a comparative planetology perspective with the Earth as reference. Our approach is based on the calculation of solutional denudation rates and allow inference of formation timescales for topographic depressions developed by chemical erosion on both planetary bodies. The model depends on the solubility of solids in liquids, the density of solids and liquids, and the average annual net rainfall rates. We compute and compare the denudation rates of pure solid organics in liquid hydrocarbons and of minerals in liquid water over Titan and Earth timescales. We then investigate the denudation rates of a superficial organic layer in liquid methane over one Titan year. At this timescale, such a layer on Titan would behave like salts or carbonates on Earth depending on its composition, which mea...

  5. The Dynamics of Titan's Convective Clouds

    Science.gov (United States)

    Rafkin, S. C.

    2012-12-01

    Titan's deep convective clouds are the most dynamic phenomena known to operate within the atmosphere of the moon. Previous studies have focused primarily on the control of these storms by the large scale thermodynamic environment, especially methane abundance, which determines the amount of convective available potential energy (CAPE). This study looks at factors in addition to the thermodynamic environment that may have a first order impact on the evolution and structure of Titan's deep convective clouds. To the extent that thunderstorms on Earth provide a reasonable analog to the storms on Titan, it is well established that CAPE alone is insufficient to determine the structure and behavior of deep convection. Wind shear—both directional and speed—is also known to exert a first order effect. The influence of both CAPE and wind speed shear is typically expressed as the ratio of the two parameters in the form of the Bulk Richardson Number. On Earth, for a fixed value of CAPE, the addition of wind speed shear (i.e., the reduction of the Bulk Richardson Number) will tend to produce storms that are longer lived, tilted upshear with height, and multi-cellular in nature. These multi-cellular storms also tend to be more violent than storms generated in low wind speed shear environments: strong winds and large hail are common. The addition of directional shear (i.e., helicity) can transform the multi-cell storms into single, intense supercell storms. These are the storms associated typically associated with tornadoes. With respect to Titan, if there is a similar dependence on the Bulk Richardson Number, then this would have implications for how long Titan's storms live, how much precipitation they can produce, the area they cover, and the strength and duration of winds. A series of numerical simulations of Titan's deep convective clouds from the Titan Regional Atmospheric Modeling System are presented. A reasonable sweep of the parameter space of CAPE and shear for

  6. Leachability of barium-radium sulphate sludges

    International Nuclear Information System (INIS)

    This paper presents results from the first phase of a research program designed to examine the leachability of radium-226 from barium-radium sulphate sludges. Batch leaching tests were performed. Results showed that liquid:solid contact time was relatively unimportant; radium in the sludge was stable in the presence of deionized water with a slight increase in the amount leached per gram of sludge occurring at higher liquid:solid ratios. Not unexpectedly, low and high values of leachant pH increased radium leaching. Both monovalent and divalent salt solutions also increased leaching; however, dissolved radium-226 activity levels in the leachate decreased as leachant molarity increased. For divalent salts this can be explained by the common ion effect; for monovalent salts it is opposite to results expected from solubility considerations. The interpretation of all results is complicated by the fact that in most tests, the amount of radium-226 present in the leachate was lower than the calculated contribution from the mother liquour present with the sludge. This apparent ability of the sludge to absorb radium from solution may be related to dissolution and reprecipitation of the sludge during the leaching tests

  7. The diagnostic value of barium enema in acute appendicitis

    International Nuclear Information System (INIS)

    Acute appendicitis is the most common acute surgical condition of the abdomen. When the clinical presentation is atypical, barium enema has proven to be safe and useful in confirming the diagnosis and reducing the negative surgical exploration. However, the performance of barium enema in acute appendicitis has known contraindication primarily because of fear of leakage by perforation of the inflamed appendix. This study using barium enema as a diagnostic aid in acute appendicitis with atypical clinical presentation was performed to further support the previously noted efficacy and safety of this procedure. The results were as followings: 1. In case of acute appendicitis with atypical clinical presentation, the use of barium enema as a diagnostic aid increased the accuracy of diagnosis and decreased the negative surgical exploration. In women between 11 to 50 years old age, especially, it played important role differentiating appendicitis from nonsurgical acute abdomen. 2. The results of the study were 92.31% in sensitivity, 7.69% in false positive, 6.9% in false negative, and 10.26% in negative appendectomy. 3. None of case of leakage of barium by perforation of the inflamed appendix was noted, therefore, barium enema was thought to be safe as a diagnostic aid in acute appendicitis. 4. A simple partial or non filling of appendix without other associated positive finding could not exclude appendicitis, therefore, close clinical observation was necessary. 5. The positive findings of barium enema and their sensitivity were as followings: 1. Non filling of appendix: 90% 2. Partial filling of appendix: 91.7% 3. Displacement or a local impression on terminal ileum: 100%

  8. ISO observations of Titan with SWS/grating

    Science.gov (United States)

    Coustenis, A.; Encrenaz, T.; Salama, A.; Lellouch, E.; Gautier, D.; Kessler, M. F.; deGraauw, T.; Samuelson, R. E.; Bjoraker, G.; Orton, G.

    1997-01-01

    The observations of Titan performed by the Infrared Space Observatory (ISO) short wavelength spectrometer (SWS), in the 2 micrometer to 45 micrometer region using the grating mode, are reported on. Special attention is given to data from Titan concerning 7 micrometer to 45 micrometer spectral resolution. Future work for improving Titan's spectra investigation is suggested.

  9. Transient features in a Titan sea

    Science.gov (United States)

    Hofgartner, J. D.; Hayes, A. G.; Lunine, J. I.; Zebker, H.; Stiles, B. W.; Sotin, C.; Barnes, J. W.; Turtle, E. P.; Baines, K. H.; Brown, R. H.; Buratti, B. J.; Clark, R. N.; Encrenaz, P.; Kirk, R. D.; Le Gall, A.; Lopes, R. M.; Lorenz, R. D.; Malaska, M. J.; Mitchell, K. L.; Nicholson, P. D.; Paillou, P.; Radebaugh, J.; Wall, S. D.; Wood, C.

    2014-07-01

    Titan's surface-atmosphere system bears remarkable similarities to Earth's, the most striking being an active, global methane cycle akin to Earth's water cycle. Like the hydrological cycle of Earth, Titan's seasonal methane cycle is driven by changes in the distribution of solar energy. The Cassini spacecraft, which arrived at Saturn in 2004 in the midst of northern winter and southern summer, has observed surface changes, including shoreline recession, at Titan's south pole and equator. However, active surface processes have yet to be confirmed in the lakes and seas in Titan's north polar region. As the 2017 northern summer solstice approaches, the onset of dynamic phenomena in this region is expected. Here we present the discovery of bright features in recent Cassini RADAR data that appeared in Titan's northern sea, Ligeia Mare, in July 2013 and disappeared in subsequent observations. We suggest that these bright features are best explained by the occurrence of ephemeral phenomena such as surface waves, rising bubbles, and suspended or floating solids. We suggest that our observations are an initial glimpse of dynamic processes that are commencing in the northern lakes and seas as summer nears in the northern hemisphere.

  10. High Resolution Camera for Mapping Titan Surface

    Science.gov (United States)

    Reinhardt, Bianca

    2011-01-01

    Titan, Saturn's largest moon, has a dense atmosphere and is the only object besides Earth to have stable liquids at its surface. The Cassini/Huygens mission has revealed the extraordinary breadth of geological processes shaping its surface. Further study requires high resolution imaging of the surface, which is restrained by light absorption by methane and scattering from aerosols. The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft has demonstrated that Titan's surface can be observed within several windows in the near infrared, allowing us to process several regions in order to create a geological map and to determine the morphology. Specular reflections monitored on the lakes of the North Pole show little scattering at 5 microns, which, combined with the present study of Titan's northern pole area, refutes the paradigm that only radar can achieve high resolution mapping of the surface. The present data allowed us to monitor the evolution of lakes, to identify additional lakes at the Northern Pole, to examine Titan's hypothesis of non-synchronous rotation and to analyze the albedo of the North Pole surface. Future missions to Titan could carry a camera with 5 micron detectors and a carbon fiber radiator for weight reduction.

  11. Titan's night-glow mechanisms

    Science.gov (United States)

    Lavvas, P.; West, R. A.; Gronoff, G.

    2014-04-01

    Observations of Titan's emissions during its 2009 eclipse by Saturn revealed a weak airglow around the moon, as well as a brighter emission from its disk (Fig.1). We explore here the potential mechanisms that could generate these emissions and more specifically the role of magnetospheric plasma and cosmic rays in the upper and lower atmosphere, respectively [2]. We consider excitation of N2 by these energy sources and calculate the resulting emissions through a detailed model of N2 airglow [3](Fig.2), followed by careful radiation transfer of the emitted photons through the atmosphere, and into the UVIS and ISS instruments (Figs 3 & 4). Our results indicate that the observed limb emissions are consistent with magnetospheric plasma energy input, while emissions instigated by cosmic ray excitation deep in the atmosphere are strongly attenuated by the haze and can not explain the observed disk emissions [4](Tables 1 & 2). We discuss possible contributions from other sources that could potentially explain the disk observations. These include airglow from other species, chemiluminescence, aerosol particle fluorescence, and scattered light from the stellar background.

  12. Occupational doses in pediatric barium meal procedures

    International Nuclear Information System (INIS)

    Ionizing radiation has become an indispensable tool when it comes to diagnosis and therapy. However, its use should happen in a rational manner, taking into account the risks to which the staff is being exposed. Barium meal (BM), or upper gastrointestinal (GI) studies, using fluoroscopy, are widely used for gastroesophageal reflux disease diagnostic in children and professionals are required to stay inside the examination room to position and immobilize pediatric patients during the procedure. Therefore, it is very important that proffessionals strictly follow the technical standards of radiation protection. According to the ICRP and the NCRP recommendations, the annual limit equivalent doses for eyes, thyroid and hands are, espectively, 20 mSv, 150 mSv and 500 mSv. Based on those data, the aim of the current study is to estimate the annual equivalent dose for eyes, thyroid and hands of professionals who perform BM procedures in children. This was done using properly package LiF:Mg,Cu,P thermoluminescent dosimeters in 37 procedures; 2 pairs were positioned near each staff´s eye, 2 pairs on each professional´s neck (on and under the lead protector) and 2 pairs on both staff´s hands. The range of the estimative annual equivalent doses, for eyes, thyroid and hands, are, respectively: 14 – 36 mSv, 7 – 22 mSv and 14 – 58 mSv. Only the closest staff to the patient exceeded the annual equivalent doses in the eyes (around 80% higher than the limit set by ICRP). However, the results from this study, for hands and thyroid, compared to similar studies, show higher values. Therefore, the optimization implementation is necessary, so that the radiation levels can be reduced. (authors)

  13. Titan's transport-driven methane cycle

    CERN Document Server

    Mitchell, Jonathan L

    2012-01-01

    The strength of Titan's methane cycle, as measured by precipitation and evaporation, is key to interpreting fluvial erosion and other indicators of the surface-atmosphere exchange of liquids. But the mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A gobal- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or $\\sim$0.04 W/m$^2$, is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations that allow atmospheric motion indicate a robust methane cycle with substantial cloud formation and/or precipitation. We argue the top-of-atmosphere radiative imbalance -- a readily observable quantity -- is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constr...

  14. Titan interaction with the supersonic solar wind

    CERN Document Server

    Bertucci, C; Kurth, W S; Hospodarsky, G; Mitchell, D; Sergis, N; Edberg, N J T; Dougherty, M K

    2014-01-01

    After 9 years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic solar wind. These unique observations reveal that Titan interaction with the solar wind is in many ways similar to un-magnetized planets Mars and Venus in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations are also relevant for unmagnetized bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.

  15. First Observations Of Titan With Herschel Spire

    Science.gov (United States)

    Courtin, Regis D.; Swinyard, B. M.; Fulton, T.; Lellouch, E.; Moreno, R.; Hartogh, P.; Jarchow, C.; Rengel, M.; HssO Team

    2010-10-01

    A Titan spectrum was recorded on June 22, 2010 with the SPIRE instrument of the Herschel Space Observatory as part of the guaranteed time key programme "Water and related chemistry in the Solar System" (KP-GT HssO). This initial spectrum, corresponding to an exposure time of 1322s, was designed as a test of the full 10h Titan observation performed on July 16, 2010. It covers the 14.6-51.8 cm-1 interval with a unapodized spectral resolution of 0.04 cm-1. Despite the limited integration time, numerous transitions are detected, notably those of CH4, CO, HCN, and of the isotopologues 13CO, C18O, H13CN, and HC15N. The analysis of this set of observations will provide new determinations of the abundances of these species, and hence new contraints on the isotopic ratios 12C/13C, 14N/15N and 16O/18O in Titan's atmosphere.

  16. Deoxidation Behavior of Alloys Bearing Barium in Molten Steel

    Institute of Scientific and Technical Information of China (English)

    LI Yang; JIANG Zhou-hua; JIANG Mao-fa; WANG Jun-wen; GU Wen-bing

    2003-01-01

    The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0.002 0 % to 0.002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.

  17. Economically dissolving barium sulfate scale with a chelating agent

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, E.A.; Scheuerman, R.E.

    1977-06-21

    A composition is described for dissolving a barium sulfate scale from a subterranean or other relatively remote location into which fluid can be flowed. Fluid is flow-flowed into the remote location so that a stream of fluid contacts and flows along the surface of the scale. The composition and flow rate of the fluid are adjusted so that (1) the scale is contacted by a stream of aqueous solution in which each portion contains enough dissolved aminopolyacetic acid salt chelating agent to dissolve barium sulfate, and (2) substantially all upstream portions of the scale are contacted by a succession of portions of the aqueous liquid which are substantially unsaturated with respect to dissolved barium-chelant complex. (5 claims)

  18. TITAN'S TRANSPORT-DRIVEN METHANE CYCLE

    International Nuclear Information System (INIS)

    The mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A global- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or ∼0.04 W m–2, is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations indicate substantial cloud formation and/or precipitation. We argue that the top-of-atmosphere (TOA) radiative imbalance is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constrains the strength of the methane cycle. Simple calculations show the TOA radiative imbalance is ∼0.5-1 W m–2 in Titan's equatorial region, which implies 2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of Titan's climate suggests this transport may occur primarily as latent heat, with net evaporation at the equator and net accumulation at higher latitudes. Thus, the methane cycle could be 10-20 times previous estimates. Opposing seasonal transport at solstices, compensation by sensible heat transport, and focusing of precipitation by large-scale dynamics could further enhance the local, instantaneous strength of Titan's methane cycle by a factor of several. A limited supply of surface liquids in regions of large surface radiative imbalance may throttle the methane cycle, and if so, we predict more frequent large storms over the lakes district during Titan's northern summer.

  19. Chapman Solar Zenith Angle variations at Titan

    Science.gov (United States)

    Royer, Emilie M.; Ajello, Joseph; Holsclaw, Gregory; West, Robert; Esposito, Larry W.; Bradley, Eric Todd

    2016-10-01

    Solar XUV photons and magnetospheric particles are the two main sources contributing to the airglow in the Titan's upper atmosphere. We are focusing here on the solar XUV photons and how they influence the airglow intensity. The Cassini-UVIS observations analyzed in this study consist each in a partial scan of Titan, while the center of the detector stays approximately at the same location on Titan's disk. We used observations from 2008 to 2012, which allow for a wide range of Solar Zenith Angle (SZA). Spectra from 800 km to 1200 km of altitude have been corrected from the solar spectrum using TIMED/SEE data. We observe that the airglow intensity varies as a function of the SZA and follows a Chapman curve. Three SZA regions are identified: the sunlit region ranging from 0 to 50 degrees. In this region, the intensity of the airglow increases, while the SZA decreases. Between SZA 50 and 100 degrees, the airglow intensity decreases from it maximum to its minimum. In this transition region the upper atmosphere of Titan changes from being totally sunlit to being in the shadow of the moon. For SZA 100 to 180 degrees, we observe a constant airglow intensity close to zero. The behavior of the airglow is also similar to the behavior of the electron density as a function of the SZA as observed by Ågren at al (2009). Both variables exhibit a decrease intensity with increasing SZA. The goal of this study is to understand such correlation. We demonstrate the importance of the solar XUV photons contribution to the Titan airglow and prove that the strongest contribution to the Titan dayglow occurs by solar fluorescence rather than the particle impact that predominates at night.

  20. Tidal Response of Titan's Lakes and Seas

    Science.gov (United States)

    Karatekin, O.; Demain, C.; Deleersnijder, E.

    2011-12-01

    The Cassini spacecraft has revealed a vast set of lakes/seas filled or partially filled with liquid hydrocarbons and empty lake basins in the high latitudes of Titan. The seas and lakes of Titan provide an opportunity to explore an exciting aqueous environment whose characteristics are very different from what we know on Earth. The lakes appear in various shapes and sizes and are filled with liquid hydrocarbons, primarily methane and ethane. Recently, the Cassini spacecraft provided observations suggesting for the first time temporal variations in lake surfaces. The variation in the shorelines can be explained by different hypothesis including evaporation and tides. During Titan's 16 day orbital period around Saturn, the time-dependent tidal response of the lakes may affect the shorelines. Although the estimated tidal amplitudes by theoretical consideration yield smaller than the observed depth changes on Ontario Lacus, tides can have more significant effects of other lakes/seas with tidal amplitudes up to several meters. In the present study, besides Ontario Lacus we also consider Ligeia Mare, one of three large methane seas discovered by Cassini in the northern hemisphere of Titan and the target for the discovery mission of Titan Mare Explorer (TiME). The tidal response of Titan's lakes an seas are investigated by means of two- dimensional nonlinear shallow water equations The governing partial differential equations on the sphere are solved using SLIM (Second-generation Louvain- la- Neuve Ice-Ocean Model - http://www.climate.be/SLIM). SLIM is a hydrodynamical model based on finite element method. As all general circulation models, it uses primitive variables as prognostic quantities. Partial differential equations are discretized on curved surfaces using triangular meshes. The mesh is generated from recursive subdivisions of the faces of an icosahedron using GMSH software.. The code has a wetting-drying algorithm. The simulations can take into account several

  1. Future Exploration of Titan -Astrobiological Aspects

    Science.gov (United States)

    Lorenz, Ralph

    The only known chemical systems sophisticated enough to execute the functions of life are those made from carbon-based compounds. Saturn's moon Titan presents us with an extensive and rich inventory of complex organics, and is therefore of great astrobiological interest. Astrobiology at Titan has two principal facets. First is the prospect of an internal water ocean (like other icy satellites, albeit perhaps with a higher concentration of ammonia and organics) and related aqueous chemistry that may occur in transient surface exposures of water in impact melt sheets or cryovolcanic flows. The other is chemistry that may occur in the nonpolar solvents ethane and methane that form Titan's polar lakes and seas. The astrobiological potential of the latter systems is essentially unknown, although the environments are more accessible to affordable exploration. Recent studies have identified many mission possibilities within the framework of a Flagship-class mission, including orbiters, landers on (organic) dunefields, landers in lakes, and aerial platforms such as Montgolfiere balloons acting in a coordinated, synergistic manner. However, such a mission is not likely to take place until circa 2030. More modest missions, that might consider one of these elements on a standalone basis, could be considered under PI-led mission categories such as New Frontiers or Discovery. A lake lander, for example, could carry a mass spectrometer to analyze the detailed composition of a lake. Even the earliest of these possibilities, the Titan Mare Explorer (TiME) Discovery proposal presently being considered, would not arrive until 2022-2023. In the meantime, the recent approval by NASA of the Cassini Solstice Mission (until 2017) will enable many new findings at Titan, in particular with regard to Titan's interior, and seasonal changes in its organic lakes.

  2. Volatile products controlling Titan's tholins production

    KAUST Repository

    Carrasco, Nathalie

    2012-05-01

    A quantitative agreement between nitrile relative abundances and Titan\\'s atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan\\'s atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O\\'Brien et al. (Sciamma-O\\'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O\\'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan\\'s INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.

  3. Radiation dose in mass screening for gastric cancer with high-concentration barium sulphate compared with moderate-concentration barium sulphate

    International Nuclear Information System (INIS)

    Full text: Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer.

  4. Statistics of Titan's South Polar Tropospheric Clouds

    OpenAIRE

    Bouchez, Antonin H.; Brown, Michael E.

    2005-01-01

    We present the first long-term study of the behavior of the sporadically observed tropospheric clouds recently discovered near Titan's south pole. We find that one or more small individual cloud systems is present in the 70°-80° south region during every night of observation. These clouds account for 0.5%-1% of Titan's 2.0 μm flux, consistent with a global cloud cover fraction of 0.2%-0.6%. Clouds observed over multiple-night observing periods remained nearly fixed in brightness and position ...

  5. Discovery of Temperate Latitude Clouds on Titan

    OpenAIRE

    Roe, H. G.; Bouchez, A. H.; Trujillo, C. A.; Schaller, E. L.; Brown, M E

    2005-01-01

    Until now, all the clouds imaged in Titan's troposphere have been found at far southern latitudes (60°-90° south). The occurrence and location of these clouds is thought to be the result of convection driven by the maximum annual solar heating of Titan's surface, which occurs at summer solstice (2002 October) in this south polar region. We report the first observations of a new recurring type of tropospheric cloud feature, confined narrowly to ~40° south latitude, which cannot be explained by...

  6. Constraints on Titan rotation from Cassini radar

    Science.gov (United States)

    Bills, B. G.; Stiles, B. W.; Kirk, R. L.

    2014-12-01

    We give an update on efforts to model the rotation of Titan, subject to constraints from Cassini radar observations. The data we are currently using includes 670 tie-points, each of which is a pair of inertial positions of a single surface point, relative to the center of mass of Titan, and the corresponding pair of observation times. The positional accuracy is of order 1 km, in each Cartesian component. A reasonably good fit to the observations is obtained with a simple model which has a fixed spin pole and a rotation rate which is a sum of a constant value and a single sinusoidal oscillation. A better fit is obtained if we insist that Titan should behave as a synchronous rotator, in the dynamical sense of keeping its axis of least inertia oriented toward Saturn. At the level of accuracy required to fit the Cassini radar data, synchronous rotation is notably different than having a uniform rate of rotation. In this case, we need to model time variations in the orbital mean longitude, which is the longitude of periapse, plus the mean anomaly. That angle varies on a wide range of times scales, including Titan's periapse precession period (703 years), Saturn's heliocentric orbital period (29.47 years), perturbations from relatively large satellites Iapetus (79.3 days), and a 4:3 mean motion resonant interaction with Hyperion (640 and 6850 days), and a linear increase at Titan's mean orbital period (15.9455 day). Our rotation model for Titan has 4 free parameters. Two of them specify the orientation of the fixed spin pole, and the other two are the effective free libration period and viscous damping time. Our dynamical model includes a damped forced longitudinal libration, in which gravitational torques attempt to align the axis of least inertia with the instantaneous direction to Saturn. For a rigid tri-axial body, with Titan's moments of inertia, the free oscillation period for longitudinal librations would be 850 days. For a decoupled elastic shell, the effective

  7. 75 FR 36629 - Barium Chloride From the People's Republic of China: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2010-06-28

    ... International Trade Administration Barium Chloride From the People's Republic of China: Continuation of... China: Final Results of Expedited Third Sunset Review of Antidumping Duty Order, 74 FR 55814 (October 29... Barium Chloride From China, 75 FR 33824 (June 15, 2010), and Barium Chloride from China (Inv. No....

  8. The adhesiometer: a simple device to measure adherence of barium sulfate to intestinal mucosa.

    Science.gov (United States)

    Salomonowitz, E; Frick, M P; Cragg, A H; Lund, G

    1984-04-01

    A simple, inexpensive device assessing barium sulfate adherence to alimentary tract mucosa was tested in an animal study using pigs and dogs. Interaction of gastric, intestinal, and colonic mucosal lining with three different barium preparations was studied. In both pigs and dogs, barium adherence to gastric mucosa was significantly stronger when compared with colonic mucosa. PMID:6608230

  9. Photoionization and Photoelectric Loading of Barium Ion Traps

    OpenAIRE

    Steele, A. V.; Churchill, L. R.; Griffin, P. F.; Chapman, M. S.

    2007-01-01

    Simple and effective techniques for loading barium ions into linear Paul traps are demonstrated. Two-step photoionization of neutral barium is achieved using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by excitation above the ionization threshold using a nitrogen gas laser (337 nm). Isotopic selectivity is achieved by using a near Doppler-free geometry for excitation of the triplet 6s6p 3P1 state. Additionally, we report a particularly simple and efficient trap loading t...

  10. Equations of state for barium in high-pressure phases

    International Nuclear Information System (INIS)

    The universal equation of state with an arbitrary reference point presented by the author (Fang Zheng-Hua 1998 Phys. Rev. B 50 16 238) is applied successfully to the analysis of the experimental compression data of barium in different structural phases (I, II, and V). The comparison given in this paper shows that this equation suits for the isothermal compression behaviour of barium in the high-pressure phases (II and V) better than the Birch-Murnaghan equation. The applicability of equations of state for solids in high-pressure phases is also discussed. (author)

  11. Kinetics of thermal decomposition of barium zirconyl oxalate

    International Nuclear Information System (INIS)

    Kinetics of the thermal decomposition of anhydrous barium zirconyl oxalate and a carbonate intermediate have been studied. Decomposition of the anhydrous oxalate, though it could be explained based on a contracting-cube model, is quite complex. Kinetics of decomposition of the intermediate carbonate Ba2Zr2O5CO3 is greatly influenced by thermal effects during its formation. (α-t) curves are sigmoidal and obey a power law equation followed by first order decay. Presence of carbon in the vacuum-prepared carbonate has a strong deactivating effect. Decomposition of the carbonate is accompanied by growth in particle size of the product barium zirconate. (Author)

  12. Photoionization and Photoelectric Loading of Barium Ion Traps

    CERN Document Server

    Steele, A V; Churchill, L R; Griffin, P F

    2007-01-01

    Simple and effective techniques for loading barium ions into linear Paul traps are demonstrated. Two-step photoionization of neutral barium is achieved using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by excitation above the ionization threshold using a nitrogen gas laser (337 nm). Isotopic selectivity is achieved by using a near Doppler-free geometry for excitation of the triplet 6s6p 3P1 state. Additionally, we report a particularly simple and efficient trap loading technique that employs an in-expensive UV epoxy curing lamp to generate photoelectrons.

  13. Esophageal intramural pseudodiverticulosis characterized by barium esophagography: a case report

    LENUS (Irish Health Repository)

    O'Connor, Owen J

    2010-05-21

    Abstract Introduction Esophageal intramural pseudodiverticulosis is a rare condition characterized by the dilatation of the submucosal glands. Case presentation We present a case of esophageal intramural pseudodiverticulosis in a 72-year-old Caucasian man who presented with dysphagia and with a background history of alcohol abuse. An upper gastrointestinal endoscopy of our patient showed an esophageal stricture with abnormal mucosal appearances, but no malignant cells were seen at biopsy. Appearances on a barium esophagram were pathognomonic for esophageal intramural pseudodiverticulosis. Conclusion We demonstrate the enduring usefulness of barium esophagography in the characterization of abnormal mucosal appearances at endoscopy.

  14. Bismuth titanate nanorods and their visible light photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn; Liu, H.D.; Lin, N.; Yu, H.Y.

    2015-02-15

    Highlights: • Bismuth titanate nanorods have been synthesized by a simple hydrothermal process. • The size of bismuth titanate nanorods can be controlled by growth conditions. • Bismuth titanate nanorods show good photocatalytic activities of methylene blue and Rhodamine B. - Abstract: Bismuth titanate nanorods have been prepared using a facile hydrothermal process without additives. The bismuth titanate products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and UV-vis diffusion reflectance spectrum. XRD pattern shows that the bismuth titanate nanorods are composed of cubic Bi{sub 2}Ti{sub 2}O{sub 7} phase. Electron microscopy images show that the length and diameter of the bismuth titanate nanorods are 50-200 nm and 2 μm, respectively. Hydrothermal temperature and reaction time play important roles on the formation and size of the bismuth titanate nanorods. UV-vis diffusion reflectance spectrum indicates that bismuth titanate nanorods have a band gap of 2.58 eV. The bismuth titanate nanorods exhibit good photocatalytic activities in the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RB) under visible light irradiation. The bismuth titanate nanorods with cubic Bi{sub 2}Ti{sub 2}O{sub 7} phase are a promising candidate as a visible light photocatalyst.

  15. Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and Source of Titan's Aerosols?

    Science.gov (United States)

    Sittler, E. C., Jr.; Hartle, R. E.; Cooper, J. F.; Johnson, R. E.; Coates, A.; dePater, imke; Strom, Daphne; Simoes, F.; Steele, A.; Robb, F.

    2007-01-01

    With the recent discovery of heavy ions, positive and negative, by the Cassini Plasma Spectrometer (CAPS) instrument in Titan's ionosphere, it reveals new possibilities for aerosol formation at Titan and the introduction of free oxygen to the aerosol chemistry from Saturn's magnetosphere with Enceladus as the primary oxygen source. One can estimate whether the heavy ions in the ionosphere are of sufficient number to account for all the aerosols, under what conditions are favorable for heavy ion formation and how they are introduced as seed particles deeper in Titan's atmosphere where the aerosols form and eventually find themselves on Titan's surface where unknown chemical processes can take place. Finally, what are the possibilities with regard to their chemistry on the surface with some free oxygen present in their seed particles?

  16. Phase transitions, dielectric properties, and vibrational study of stannates perovskites Sr{sub 1−x}Er{sub x}SnO{sub 3−δ}

    Energy Technology Data Exchange (ETDEWEB)

    Ouni, S.; Nouri, S. [Unité de recherché de chimie des matériaux et de l’environnement UR11ES25, ISSBAT, Université de Tunis ElManar 9, Avenue Dr. Zoheir Safi, 1006 Tunis (Tunisia); Khemakhem, H. [Laboratoire des matériaux ferroélectriques (LFM), Département de Physique, Faculté des Sciences de Sfax, Sfax (Tunisia); Ben Hassen, R., E-mail: rached.benhassen@fss.rnu.tn [Unité de recherché de chimie des matériaux et de l’environnement UR11ES25, ISSBAT, Université de Tunis ElManar 9, Avenue Dr. Zoheir Safi, 1006 Tunis (Tunisia)

    2014-03-01

    Graphical abstract: The diffuseness of the phase transition of the Sr{sub 1−x}Er{sub x}SnO{sub 3−δ} enhances with the increasing of erbium content. These compounds were found to undergo phase transitions with increasing temperature. - Highlights: • Substitution Sr/Er in the alkaline earth cage modifies the thermally induced disorder. • Two phase transitions have been observed by DSC. • The dielectric constant increases with erbium substitution. • Dielectric loss increases exponentially with temperature. • The conductivity contribution is mainly due to hopping process. - Abstract: A polycrystalline stannates perovskites Sr{sub 1−x}Er{sub x}SnO{sub 3−δ} (x = 0.00, 0.01 and 0.03) were synthesized by sol–gel method and their vibrational properties were investigated using Raman scattering. The substitution of Er in the Sr site, results in a slight change of the position of the Raman spectrum bands. The differential scanning calorimetry (DSC) shows two phase transitions at 532 K and 634 K for Sr{sub 0.99}Er{sub 0.01}SnO{sub 3−δ}. The dielectric behavior of each solid solution (x = 0.01 and x = 0.03) has been studied as a function of temperature and frequency and has confirmed the observed phase transitions. The diffuseness of the phase transitions of these materials enhances with the increasing of erbium content. The dielectric constant showed a strong increase near the phase transitions temperature which value depends with frequency. This phenomenon is usually observed in relaxor materials. The conduction and the dielectric relaxation are attributed to hopping of electrons among Sn{sup 2+} and Sn{sup 4+} ions.

  17. STUDY ON THE REMOVAL OF ANTIMONY FOR PRODUCING SODIUM STANNATE BY TIN SLAG%锡渣生产锡酸钠中除锑的研究

    Institute of Scientific and Technical Information of China (English)

    卢丹艳

    2012-01-01

    利用生产硫酸亚锡、氯化亚锡、锡:扮的含锡废料生产锡酸钠,生产成本低,但在这过程中需要除去的杂质也相对比较多。文章对除锑的工艺参数和条件进行了研究,重点探讨了除锑温度、除锑时间、除锑后溶液静置沉降时间等因素对锑效果的影响。结果表明,采用该工艺,Sb的脱除率为95.3%,产品质量符合Sn-42等级标准。%waste material that contains tin and can be used for producing Stannous sulfate, Stannous chloride and Tin powder is use for producing Sodium stannate. The cost of production may stay at a relative low level. But It needs to get rid of More impurities, Relatively speaking .In this paper, the process parameters and conditions of the removal of Antimony are studied. The factors such as the temperature and time of the removal of Antimony and time of sedimentation time of the Solution are discussed, which have an influence on the removal of Antimony. It is shown that, using this technology, removal rate of Sb is 95.3%, and the Product quality is In accordance with the grading standard of Sn 42.

  18. Chemical abundance analysis of 19 barium stars

    Science.gov (United States)

    Yang, Guo-Chao; Liang, Yan-Chun; Spite, Monique; Chen, Yu-Qin; Zhao, Gang; Zhang, Bo; Liu, Guo-Qing; Liu, Yu-Juan; Liu, Nian; Deng, Li-Cai; Spite, Francois; Hill, Vanessa; Zhang, Cai-Xia

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures Teff, surface gravities log g, metallicity [Fe/H] and microturbulence velocity ξt) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants as indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their Na, Al, α- and iron-peak elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-capture) process elements relative to the Sun. Their median abundances of [Ba/Fe], [La/Fe] and [Eu/Fe] are 0.54, 0.65 and 0.40, respectively. The Y I and Zr I abundances are lower than Ba, La and Eu, but higher than the α- and iron-peak elements for the strong Ba stars and similar to the iron-peak elements for the mild stars. There exists a positive correlation between Ba intensity and [Ba/Fe]. For the n-capture elements (Y, Zr, Ba, La), there is an anti-correlation between their [X/Fe] and [Fe/H]. We identify nine of our sample stars as strong Ba stars with [Ba/Fe] >0.6 where seven of them have Ba intensity Ba=2-5, one has Ba=1.5 and another one has Ba=1.0. The remaining ten stars are classified as mild Ba stars with 0.17<[Ba/Fe] <0.54.

  19. Titan Mare Explorer (time): A Discovery Mission To A Titan Sea

    Science.gov (United States)

    Stofan, Ellen R.; Lunine, J.; Lorenz, R.; Aharonson, O.; Bierhaus, E.; Clark, B.; Kirk, R.; Kantsiper, B.; Morse, B.

    2009-09-01

    The discovery of lakes and seas in Titan's high latitudes confirmed the expectation that liquid hydrocarbons exist on the surface of the haze-shrouded moon. The lakes and seas fill through drainage of subsurface runoff and/or intersection with the subsurface alkanofer, providing the first evidence for an active condensable-liquid hydrological cycle on another planetary body. The unique nature of Titan's methane cycle, along with the prebiotic chemistry and implications for habitability, make the lakes and seas of the highest scientific priority for in situ investigation. The Titan Mare Explorer mission is an ASRG (Advanced Stirling Radioisotope Generator)-powered mission to a sea on Titan. The mission would be the first exploration of a planetary sea beyond Earth, would demonstrate the ASRG both in deep space and a non-terrestrial atmosphere environment, and pioneer low-cost outer planet missions. The scientific objectives of the mission are to: determine the chemistry of a Titan sea to constrain Titan's methane cycle; determine the depth of a Titan sea; characterize physical properties of liquids; determine how the local meteorology over the seas ties to the global cycling of methane; and analyze the morphology of sea surfaces, and if possible, shorelines, in order to constrain the kinetics of liquids and better understand the origin and evolution of Titan lakes and seas. The focused scientific goals, combined with the new ASRG technology and the unique mission design, allows for a new class of mission at much lower cost than previous outer planet exploration has required.

  20. The Titan Mare Explorer Mission (TiME): A Discovery mission to a Titan sea

    Science.gov (United States)

    Stofan, E. R.; Lunine, J. I.; Lorenz, R. D.; Aharonson, O.; Bierhaus, E.; Boldt, J.; Clark, B.; Griffith, C.; Harri, A.-M.; Karkoschka, E.; Kirk, R.; Mahaffy, P.; Newman, C.; Ravine, M.; Trainer, M.; Turtle, E.; Waite, H.; Yelland, M.; Zarnecki, J.

    2011-10-01

    The Titan Mare Explorer (TiME) is a Discovery class mission to Titan, and would be the first in situ exploration of an extraterrestrial sea. The mission is one of three recently chosen by NASA for a Phase A study; one mission will be downselected for launch in the summer of 2012. TiME is a lake lander, which would float on the surface of a sea, performing chemical, meteorological and visual observations.

  1. Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper

    Science.gov (United States)

    Lopes, R.M.C.; Mitchell, K.L.; Stofan, E.R.; Lunine, J.I.; Lorenz, R.; Paganelli, F.; Kirk, R.L.; Wood, C.A.; Wall, S.D.; Robshaw, L.E.; Fortes, A.D.; Neish, C.D.; Radebaugh, J.; Reffet, E.; Ostro, S.J.; Elachi, C.; Allison, M.D.; Anderson, Y.; Boehmer, R.; Boubin, G.; Callahan, P.; Encrenaz, P.; Flamini, E.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.A.; Johnson, W.T.K.; Kelleher, K.; Muhleman, D.O.; Ori, G.; Orosei, R.; Picardi, G.; Posa, F.; Roth, L.E.; Seu, R.; Shaffer, S.; Soderblom, L.A.; Stiles, B.; Vetrella, S.; West, R.D.; Wye, L.; Zebker, H.A.

    2007-01-01

    The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan. ?? 2006 Elsevier Inc.

  2. Cassini-Huygens results on Titan's surface

    Institute of Scientific and Technical Information of China (English)

    Athena Coustenis; Mathieu Hirtzig

    2009-01-01

    Our understanding of Titan, Saturn's largest satellite, has recently been consid-erably enhanced, thanks to the Cassini-Huygens mission. Since the Saturn Orbit Injection in July 2004, the probe has been harvesting new insights of the Kronian system. In par-ticular, this mission orchestrated a climax on January 14, 2005 with the descent of the Huygens probe into Titan's thick atmosphere. The orbiter and the lander have provided us with picturesque views of extraterrestrial landscapes, new in composition but reassuringly Earth-like in shape. Thus, Saturn's largest satellite displays chains of mountains, fields of dark and damp dunes, lakes and possibly geologic activity. As on Earth, landscapes on Titan are eroded and modeled by some alien hydrology: dendritic systems, hydrocarbon lakes, and methane clouds imply periods of heavy rainfalls, even though rain was never observed directly. Titan's surface also proved to be geologically active - today or in the recent past - given the small number of impact craters listed to date, as well as a few possible cryovolcanic features. We attempt hereafter a synthesis of the most significant results of the Cassini-Huygens endeavor, with emphasis on the surface.

  3. Mountains on Titan observed by Cassini Radar

    Science.gov (United States)

    Radebaugh, J.; Lorenz, R.D.; Kirk, R.L.; Lunine, J.I.; Stofan, E.R.; Lopes, R.M.C.; Wall, S.D.

    2007-01-01

    The Cassini Titan Radar mapper has observed elevated blocks and ridge-forming block chains on Saturn's moon Titan demonstrating high topography we term "mountains." Summit flanks measured from the T3 (February 2005) and T8 (October 2005) flybys have a mean maximum slope of 37?? and total elevations up to 1930 m as derived from a shape-from-shading model corrected for the probable effects of image resolution. Mountain peak morphologies and surrounding, diffuse blankets give evidence that erosion has acted upon these features, perhaps in the form of fluvial runoff. Possible formation mechanisms for these mountains include crustal compressional tectonism and upthrusting of blocks, extensional tectonism and formation of horst-and-graben, deposition as blocks of impact ejecta, or dissection and erosion of a preexisting layer of material. All above processes may be at work, given the diversity of geology evident across Titan's surface. Comparisons of mountain and blanket volumes and erosion rate estimates for Titan provide a typical mountain age as young as 20-100 million years. ?? 2007 Elsevier Inc. All rights reserved.

  4. Dunes on Titan observed by Cassini Radar

    Science.gov (United States)

    Radebaugh, J.; Lorenz, R.D.; Lunine, J.I.; Wall, S.D.; Boubin, G.; Reffet, E.; Kirk, R.L.; Lopes, R.M.; Stofan, E.R.; Soderblom, L.; Allison, M.; Janssen, M.; Paillou, P.; Callahan, P.; Spencer, C.; The Cassini Radar Team

    2008-01-01

    Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ??30?? of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other aeolian forms indicate a single, dominant wind direction aligned with the dune axis plus lesser, off-axis or seasonally alternating winds. Global compilations of dune orientations reveal the mean wind direction is dominantly eastwards, with regional and local variations where winds are diverted around topographically high features, such as mountain blocks or broad landforms. Global winds may carry sediments from high latitude regions to equatorial regions, where relatively drier conditions prevail, and the particles are reworked into dunes, perhaps on timescales of thousands to tens of thousands of years. On Titan, adequate sediment supply, sufficient wind, and the absence of sediment carriage and trapping by fluids are the dominant factors in the presence of dunes. ?? 2007 Elsevier Inc. All rights reserved.

  5. Ion Escape from the Ionosphere of Titan

    Science.gov (United States)

    Hartle, R.; Sittler, E.; Lipatov, A.

    2008-01-01

    Ions have been observed to flow away from Titan along its induced magnetic tail by the Plasma Science Instrument (PLS) on Voyager 1 and the Cassini Plasma Spectrometer (CAPS) on Cassini. In both cases, the ions have been inferred to be of ionospheric origin. Recent plasma measurements made at another unmagnetized body, Venus, have also observed similar flow in its magnetic tail. Much earlier, the possibility of such flow was inferred when ionospheric measurements made from the Pioneer Venus Orbiter (PVO) were used to derive upward flow and acceleration of H(+), D(+) and O(+) within the nightside ionosphere of Venus. The measurements revealed that the polarization electric field in the ionosphere produced the principal upward force on these light ions. The resulting vertical flow of H(+) and D(+) was found to be the dominant escape mechanism of hydrogen and deuterium, corresponding to loss rates consistent with large oceans in early Venus. Other electrodynamic forces were unimportant because the plasma beta in the nightside ionosphere of Venus is much greater than one. Although the plasma beta is also greater than one on Titan, ion acceleration is expected to be more complex, especially because the subsolar point and the subflow points can be 180 degrees apart. Following what we learned at Venus, upward acceleration of light ions by the polarization electric field opposing gravity in the ionosphere of Titan will be described. Additional electrodynamic forces resulting from the interaction of Saturn's magnetosphere with Titan's ionosphere will be examined using a recent hybrid model.

  6. Detection of Propene in Titan's Stratosphere

    Science.gov (United States)

    Nixon, C. A.; Jennings, D. E.; Bézard, B.; Vinatier, S.; Teanby, N. A.; Sung, K.; Ansty, T. M.; Irwin, P. G. J.; Gorius, N.; Cottini, V.; Coustenis, A.; Flasar, F. M.

    2013-10-01

    The Voyager 1 flyby of Titan in 1980 gave a first glimpse of the chemical complexity of Titan's atmosphere, detecting many new molecules with the infrared interferometer spectrometer (IRIS). These included propane (C3H8) and propyne (CH3C2H), while the intermediate-sized C3H x hydrocarbon (C3H6) was curiously absent. Using spectra from the Composite Infrared Spectrometer on Cassini, we show the first positive detection of propene (C3H6) in Titan's stratosphere (5σ significance), finally filling the three-decade gap in the chemical sequence. We retrieve a vertical abundance profile from 100-250 km, that varies slowly with altitude from 2.0 ± 0.8 ppbv at 125 km, to 4.6 ± 1.5 ppbv at 200 km. The abundance of C3H6 is less than both C3H8 and CH3C2H, and we remark on an emerging paradigm in Titan's hydrocarbon abundances whereby alkanes > alkynes > alkenes within the C2H x and C3H x chemical families in the lower stratosphere. More generally, there appears to be much greater ubiquity and relative abundance of triple-bonded species than double-bonded, likely due to the greater resistance of triple bonds to photolysis and chemical attack.

  7. Detection of Propene in Titan's Stratosphere

    CERN Document Server

    Nixon, Conor A; Bezard, Bruno; Vinatier, Sandrine; Teanby, Nicholas A; Sung, Keeyoon; Ansty, Todd M; Irwin, Patrick G J; Gorius, Nicolas; Cottini, Valeria; Coustenis, Athena; Flasar, F Michael

    2013-01-01

    The Voyager 1 flyby of Titan in 1980 gave a first glimpse of the chemical complexity of Titan's atmosphere, detecting many new molecules with the infrared spectrometer (IRIS). These included propane (C3H8) and propyne (CH3C2H), while the intermediate-sized C3Hx hydrocarbon (C3H6) was curiously absent. Using spectra from the Composite Infrared Spectrometer (CIRS) on Cassini, we show the first positive detection of propene (C3H6) in Titan's stratosphere (5-sigma significance), finally filling the three-decade gap in the chemical sequence. We retrieve a vertical abundance profile from 100-250 km, that varies slowly with altitude from ~2 ppbv at 100 km, to ~5 ppbv at 200 km. The abundance of C3H6 is less than both C3H8 and CH3C2H, and we remark on an emerging paradigm in Titan's hydrocarbon abundances whereby: alkanes > alkynes > alkenes within the C2Hx and C3Hx chemical families in the lower stratosphere. More generally, there appears to be much greater ubiquity and relative abundance of triple-bonded species th...

  8. Synthesis of Nanocrystalline Barium Ferrite in Ethanol/Water Media

    Institute of Scientific and Technical Information of China (English)

    M.Montazeri-Pour; A.Ataie

    2009-01-01

    Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment. Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process. Coprecipitated powders were annealed at various temperatures for 1 h. FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), DTA/TGA (differential thermal analy-sis/thermogravimetric analysis) and SEM (scanning electron microscopy) techniques were used to evaluate powder particle characteristics. DTA/TGA results confirmed by those obtained from XRD indicated that the formation of barium ferrite occurs in sample synthesized in ethanol/water solution at a relatively low temperature of 631℃. Nano-size particles of barium ferrite with mean particle size of almost 75 and 100 nm were observed in the SEM micrographs of the samples synthesized in ethanol/water solution after annealing at 700 and 800℃ for 1 h, respectively.

  9. CNO and F abundances in the barium star HD 123396

    CERN Document Server

    Alves-Brito, Alan; Yong, David; Meléndez, Jorge; Vásquez, Sergio

    2011-01-01

    [Abridged] Barium stars are moderately rare chemically peculiar objects which are believed to be the result of the pollution of an otherwise normal star by material from an evolved companion on the asymptotic giant branch (AGB). We aim to derive carbon, nitrogen, oxygen, and fluorine abundances for the first time from infrared spectra of the barium red giant star HD 123396 to quantitatively test AGB nucleosynthesis models for producing barium stars via mass accretion. High-resolution and high S/N infrared spectra were obtained using the Phoenix spectrograph mounted at the Gemini South telescope. The abundances were obtained through spectrum synthesis of individual atomic and molecular lines, using the MOOG stellar line analysis program together with Kurucz's stellar atmosphere models. The analysis was classical, using 1D stellar models and spectral synthesis under the assumption of local thermodynamic equilibrium. We confirm that HD 123396 is a metal-deficient barium star ([Fe/H] = -1.05), with A(C) = 7.88, A...

  10. Removal of barium and radium from groundwater. Environmental research brief

    International Nuclear Information System (INIS)

    A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium removal processes were also characterized, and processes suitable for treatment of ion-exchange brines were evaluated. The report discusses two ion-exchange processes that can be used for barium and radium removal accompanied by either partial or no hardness removal. The calcium-form, strong-acid ion-exchange resin can be used for barium and radium removal without significant change in hardness or the concentration of other salts. This resin can be regenerated with CaC12 brine. The radium-selective complexer (RSC) will remove radium without altering hardness or other salt concentration. The capacity of this resin for waters with low total dissolved solids (TDS) (<1000 to 2000 mg/L TDS) is in excess of 30,000 pCi/dry g; however, if the TDS is increased to about 40,000 mg/L, the capacity drops to 200 to 300 pCi/dry g. Thus using this resin to remove radium from spent brine does not appear feasible

  11. Titan: a laboratory for prebiological organic chemistry

    Science.gov (United States)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1992-01-01

    When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

  12. Waves and horizontal structures in Titan's thermosphere

    Science.gov (United States)

    Müller-Wodarg, I. C. F.; Yelle, R. V.; Borggren, N.; Waite, J. H.

    2006-12-01

    The Ion Neutral Mass Spectrometer (INMS) on board the Cassini spacecraft carried out in situ measurements of neutral gas composition above 1025 km altitude in Titan's atmosphere during its flybys in October 2004 (TA) and April 2005 (T5). Strong perturbations are present in the N2 and CH4 densities which we interpret as vertically propagating waves. Typical vertical wavelengths range from 170 to 360 km with density and pressure amplitudes reaching 4-12% of the background values and temperature amplitudes of 5-10 K. Amplitudes over our sampled height range, 1025 (T5) or 1176 (TA) to 1600 km, remain roughly constant, implying that the exponential increase in wave amplitudes with height due to the decrease of density is offset by damping. This finding allows us to constrain the wave periods to values in the order of hours. Estimates of wave-induced acceleration of the background thermosphere suggest that the waves we observe could deposit considerable momentum in Titan's thermosphere, thereby coupling the dynamics of the upper atmosphere with that of the middle atmosphere. In addition, we infer latitudinal structures in Titan's thermosphere with a factor of 3-4 increase of mass densities from pole to equator in the northern hemisphere. A preliminary evaluation of local time variations suggests densities and thermospheric temperatures to be largest near dusk, contradicting expectations for a thermosphere driven energetically and dynamically primarily by solar EUV. From the latitudinal density gradients we derived zonal wind speeds of around 245 ± 50 ms-1, implying that Titan's thermosphere, like its stratosphere, could be superrotating. Our analyses were based on the TA and TS flybys only, and future Cassini Titan flybys could either support or invalidate our findings.

  13. Effect of Barium Titanate (BaTiO3) Additive on the Short-Term DC Breakdown strength of Polyethylene

    DEFF Research Database (Denmark)

    Henk, Peter O

    1996-01-01

    The use of additives to insulting materials is one of the methods to improve certain properties of these materials. Additives can also be used to provide more insight into some processes like conduction, space charge formation and breakdown under certain conditions of field application.In the pre...

  14. Quasi-rapid thermal annealing studies on barium strontium titanate thin films deposited on fused silica substrates

    Energy Technology Data Exchange (ETDEWEB)

    Venkata Saravanan, K., E-mail: vsk@ua.pt; James Raju, K.C., E-mail: kcjrsp@uohyd.ernet.in

    2013-09-15

    Highlights: •Nano-crystalline BST films were obtained on amorphous fused silica substrates. •Crystallization was induced by quasi-RTA, a cost effective approach. •No evidence of residual strain or surface layer was observed in the annealed films. •Dielectric properties @10 GHz were measured using split post dielectric resonator. •Crystallization result in higher density, conductivity, dielectric const. and tan δ. -- Abstract: Thin films of (Ba{sub 0.5},Sr{sub 0.5})TiO{sub 3} (BST5) were deposited at ambient temperature on fused silica substrates by RF magnetron sputtering technique. Nano-crystalline films were obtained upon quasi-rapid thermal annealing (Q-RTA) at temperatures ⩾800 °C for 60 s. The influence of Q-RTA temperature on the structural, morphological, optical and microwave dielectric properties of BST5 thin films have been investigated. The as-deposited and Q-RTA films annealed up to 700 °C were amorphous in nature. On increasing the Q-RTA temperature to 800 °C and above resulted in an amorphous–crystalline phase transition in the films. All the crystalline films show similar full width at half maxima (FWHM) and hence, similar crystallite size of about 12 ± 1 nm. The amorphous–crystalline transition was accompanied by a decrease in the optical band gap from 4.5 to 3.6 and increase in the refractive index from 1.9 to 2.2 as well as in the microwave dielectric constant from 40 to 262. The Root Mean Square roughness (RMS{sub roughness}) as measured from AFM show an increase from 0.6 nm to 5.6 nm with an increase in Q-RTA temperature from 400 °C to 1000 °C.

  15. Discontinuous temperature-dependent macroscopic strain due to ferroelastic domain switching and structural phase transitions in barium strontium titanate

    International Nuclear Information System (INIS)

    Remnant strain has been measured as a function of temperature in (Ba0.8Sr0.2)TiO3 (BST) ceramic by mechanical poling in three point bending configuration. BST ceramic exhibits recoverable macroscopic strain with shape memory effect and three jumps in the temperature-dependent strain during thermal cycling under applied force. The jumps are associated with the three structural phase transitions of BST, as confirmed by the simultaneous measurements of dynamic modulus and internal friction. In addition, the orthorhombic phase of BST exhibits a significantly higher strain comparing to that in the tetragonal and rhombohedral phases. X-ray diffraction confirms that the macroscopic strain is due to ferroelastic domain switching and particularly the dominant contribution to the higher macroscopic strain at orthorhombic phase is the higher probability of non-180 deg. domain switching rather than the variation of domain switching strain at different phases

  16. Correlation between nanostructural and electrical properties of barium titanate-based glass-ceramic nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Al-Assiri, M.S., E-mail: msassiri@kku.edu.sa [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); El-Desoky, M.M., E-mail: mmdesoky@gmail.com [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt)

    2011-09-08

    Highlights: > Glasses have been transformed into nanomaterials by annealing at crystallization temperature. > Glass-ceramic nano-composites are important because of their new physical. > Grain sizes are the most significant structural parameter in electronic nanocrystalline phases. > These phases are very high electrical conductivity. > Hence, glass-ceramic nanocrystals are expected to be used, as gas sensors. - Abstract: Glasses in the system BaTiO{sub 3}-V{sub 2}O{sub 5}-Bi{sub 2}O{sub 3} have been transformed into glass-ceramic nano-composites by annealing at crystallization temperature T{sub cr} determined from DSC thermograms. After annealing they consist of small crystallites embedded in glassy matrix. The crystallization temperature T{sub cr} increases with increasing BaTiO{sub 3} content. XRD and TEM of the glass-ceramic nano-composites show that nanocrystals were embedded in the glassy matrix with an average grain size of 25 nm. The resulting materials exhibit much higher electrical conductivity than the initial glasses. It was postulated that the major role in the conductivity enhancement of these nanomaterials is played by the developed interfacial regions between crystalline and amorphous phases, in which the concentration of V{sup 4+}-V{sup 5+} pairs responsible for electron hopping, has higher than values that inside the glassy matrix. The experimental results were discussed in terms of a model proposed in this work and based on a 'core-shell' concept. From the best fits, reasonable values of various small polaron hopping (SPH) parameters were obtained. The conduction was attributed to non-adiabatic hopping of small polaron.

  17. Study on the Microstructure and Dielectric Properties of Barium Strontium Titanate Thin Films Prepared by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    SHAN Lian-wei; ZHANG Xian-you; DONG Li-min; WU Ze; HAN Zhi-dong; FU Xing-hua; HOU Wen-ping

    2006-01-01

    Sr0.5Ba0.5-xBixTiO3 (BST) thin films were fabricated on a Pt/SiO2/Si substrate by the sol-gel method. Then follows an investigation of the influences of bismuth (Bi) on the microstructures and the dielectric properties of Sr0.5Ba0.5-xBixTiO3 (BST) thin films. The microstructures of the BST thin films were examined by the XRD and the TEM techniques. Tetragonal perovskite crystal grains were observed in BST thin films. Increasing Bi3+ doping ration in BST will lead to decrease of the grain size. It is found that Bi3+ doping decreases the dielectric loss and improves the frequency dispersion of the BST thin films. Not only is compressed the peak of temperature-dependence of dielectric constant of Bi3+-doped BST thin films but also moves into the low-temperature region. Moreover, the average Curie temperature decreases gradually with the Bi3+ contents increasing.

  18. Effect of rare earth substitution on properties of barium strontium titanate ceramic and its multiferroic composite with nickel cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Pahuja, Poonam [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kotnala, R.K. [National Physical Laboratory, Delhi 110012 (India); Tandon, R.P., E-mail: rt241150@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2014-12-25

    Highlights: • Rare earth ions Dy{sup 3+}, Gd{sup 3+} and Sm{sup 3+} have been substituted in Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST). • Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} has been used as ferrimagnetic phase to obtain composites. • Substitution of these ions increases dielectric constant of BST and composites. • Magnetoelectric coefficient of composites increases on substitution of these ions. - Abstract: Effect of substitution of rare earth ions (Dy{sup 3+}, Gd{sup 3+} and Sm{sup 3+}) on various properties of Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST) i.e. the composition Ba{sub 0.95−1.5x}Sr{sub 0.05}R{sub x}TiO{sub 3} (where x = 0.00, 0.01, 0.02, 0.03 and R are rare earths Dy, Gd, Sm) and that of their multiferroic composite with Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (NCF) has been studied. Shifting of peaks corresponding to different compositions in the X-ray diffraction pattern confirmed the substitution of rare earth ions at both Ba{sup 2+} and Ti{sup 4+} sites in BST. It is clear from scanning electron microscopy (SEM) images that rare earth substitution in BST increases its grain size in both pure and composite samples. Substitution of rare earth ions results in increase in value of dielectric constant of pure and composite samples. Sm substitution in BST significantly decreases its Curie temperature. Dy substituted pure and composite samples possess superior ferroelectric properties as confirmed by polarization vs electric field (P–E) loops. Composite samples containing Dy, Gd and Sm substituted BST as ferroelectric phase possess lower values of remanent and saturation magnetizations in comparison to composite sample containing pure BST as ferroelectric phase (BSTC). Rare earth substituted composite samples possess higher value of magnetoelectric coefficient as compared to that for BSTC.

  19. Effect of Fe{sup 3+} substitution on structural, optical and magnetic properties of barium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Dang, N.V.; Dung, N.T. [Department of Physics and Technology, Thai Nguyen University of Science, Thai Nguyen City (Viet Nam); Phong, P.T., E-mail: ptphong.nh@khanhhoa.edu.vn [Department of Natural Sciences, Nha Trang Pedagogic College, 1- Nguyen Chanh Street, Nha Trang City, Khanh Hoa Province (Viet Nam); Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, 707 Suckjang-dong, Gyeongju-Si, Gyeongbuk 780-714 (Korea, Republic of); Lee, In-Ja, E-mail: lij@dongguk.ac.kr [Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, 707 Suckjang-dong, Gyeongju-Si, Gyeongbuk 780-714 (Korea, Republic of)

    2015-01-15

    Multiferroic BaTi{sub 1−x}Fe{sub x}O{sub 3} (0≤x≤0.12) materials were synthesized using the solid-state reaction method. The influence of Fe on the crystalline structure, the electronic structure, the optical properties and the magnetic property of BaTi{sub 1−x}Fe{sub x}O{sub 3} samples were investigated. The obtained X-ray diffraction patterns, Raman and UV–vis spectra showed that the structure of the material sensitively depends on Fe dopant content, x, and transforms gradually from the tetragonal (P4mm) phase to the hexagonal (P6{sub 3}/mmc) one with increasing x. The photoluminescence emission of BaTi{sub 1−x}Fe{sub x}O{sub 3} was attributed to structural disorder. All of the samples exhibit both ferroelectricity and ferromagnetism at room temperature. The relaxor like behavior was observed for all samples. The magnetization at a magnetic field of 1 T abnormally depends on x, increases up to 0.1 then decreases monotonously afterward. This anomaly in the magnetic behavior can be explained in terms of the changes in the oxidation state of ions such as the Fe{sup 3+}-to-Fe{sup 4+} and/or Ti{sup 4+}-to-Ti{sup 3+} change induced by oxygen vacancies. The substitution of Fe into Ti sites also causes the changes in the conductivity of the material and impurity (acceptor) levels in the band gap, which can be evident from the absorption spectra, and time-dependent leakage current measured at room temperature.

  20. Barium titanate ceramic inks for continuous ink-jet printing synthesized by mechanical mixing and sol-gel methods

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhen-jun; YANG Zheng-fang; YUAN Qi-ming

    2008-01-01

    Ink-jet printing of ceramic thick films is one of low cost on-site ceramic pattern fabrication methods. It is necessary to investigate the rheological behaviour of ceramic inks and drying behaviour of droplets. Two kinds of BaTiO3 ceramic inks were prepared by mechanical mixing and sol-gel methods, respectively. The effect of preparation parameters, such as quantity of polyacrylic acid(PAA) and solid content, on physicochemical and rheologic properties of the ceramic inks was investigated. The results show that they satisfy the requirements of continuous ink-jet printing. The appearances of printed dots and single printed layers were observed by SEM. The SEM images indicate that dots printed with mixing method ink are in ring shape, and dots printed with sol-gel method ink are in pancake shape, so the printed layer surface with the latter ink is smoother. The causes of these phenomena were discussed.

  1. Crystallization resistance of barium titanate zirconate ultrathin films from aqueous CSD: a study of cause and effect

    OpenAIRE

    Hardy, An; Van Elshocht, Sven; Knaepen, Werner; D'Haen, Jan; Conard, Thierry; Brijs, Bert; Vandervorst, Wilfred; Pourtois, Geoffrey; Kittl, Jorge; Detavernier, Christophe; Heyns, Marc; Van Bael, Marlies; Van den Rul, Heidi; Mullens, Jules

    2009-01-01

    Ultrathin BaZr0.8Ti0.2O3 films (t < 30 nm) on SiOx/Si substrates were obtained by means of aqueous chemical solution deposition (CSD). Though the precursor crystallized into cubic perovskite powder at 600 degrees C, ultrathin films only crystallized at 950 to 1000 degrees C, even after addition of excess Ba to compensate for loss of Ba. Films with thickness above 100 nm, on the other hand, crystallized readily around 650 degrees C. The crystallization is related to film thickness, affecting t...

  2. Description of tritium release from lithium titanate at constant temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pena, L.; Lagos, S.; Jimenez, J.; Saravia, E. [Comision Chilena de Energia Nuclear, Santiago (Chile)

    1998-03-01

    Lithium Titanate Ceramics have been prepared by the solid-state route, pebbles and pellets were fabricated by extrusion and their microstructure was characterized in our laboratories. The ceramic material was irradiated in the La Reina Reactor, RECH-1. A study of post-irradiation annealing test, was performed measuring Tritium release from the Lithium Titanate at constant temperature. The Bertone`s method modified by R. Verrall is used to determine the parameters of Tritium release from Lithium Titanate. (author)

  3. Planetary radio astronomy observations during the Voyager 1 Titan flyby

    Science.gov (United States)

    Daigne, G.; Pedersen, B. M.; Kaiser, M. L.; Desch, M. D.

    1982-01-01

    During the Voyager 1 Titan flyby, unusual radio emissions were observed by the planetary radio astronomy experiment in the 20- to 97-kHz frequency range. It is shown that Titan itself is not the source of the observed radio emission. The emission features are attributed to modification of the normal Saturn kilometric radiation by propagation effects in enhanced density structures within the Titan wake. Furthermore, spiky emissions observed in the magnetic wake of Titan are interpreted in terms of local electrostatic instabilities at the electron plasma frequency. From these measurements a range of electron densities in the wake region is derived, and the consistency of the results is discussed.

  4. Remember the Titans: A Theoretical Analysis

    Directory of Open Access Journals (Sweden)

    Rameca Leary

    2013-06-01

    Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research. 

  5. Remember the Titans: A Theoretical Analysis

    Directory of Open Access Journals (Sweden)

    Rameca Leary

    2013-06-01

    Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research.

  6. Big Impacts and Transient Oceans on Titan

    Science.gov (United States)

    Zahnle, K. J.; Korycansky, D. G.; Nixon, C. A.

    2014-01-01

    We have studied the thermal consequences of very big impacts on Titan [1]. Titan's thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globally-averaged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and enough methane underground to saturate the regolith to the surface. We assume that half of the impact energy is immediately available to the atmosphere and surface while the other half is buried at the site of the crater and is unavailable on time scales of interest. The atmosphere and surface are treated as isothermal. We make the simplifying assumptions that the crust is everywhere as methane saturated as it was at the Huygens landing site, that the concentration of methane in the regolith is the same as it is at the surface, and that the crust is made of water ice. Heat flow into and out of the crust is approximated by step-functions. If the impact is great enough, ice melts. The meltwater oceans cool to the atmosphere conductively through an ice lid while at the base melting their way into the interior, driven down in part through Rayleigh-Taylor instabilities between the dense water and the warm ice. Topography, CO2, and hydrocarbons other than methane are ignored. Methane and ethane clathrate hydrates are discussed quantitatively but not fully incorporated into the model.

  7. Ceria and strontium titanate based electrodes

    DEFF Research Database (Denmark)

    2010-01-01

    A ceramic anode structure obtainable by a process comprising the steps of: (a) providing a slurry by dispersing a powder of an electronically conductive phase and by adding a binder to the dispersion, in which said powder is selected from the group consisting of niobium-doped strontium titanate......) with the precursor solution of step (c),(e) subjecting the resulting structure of step (d) to calcination, and (f) conducting steps (d)-(e) at least once....

  8. Hardening of Titan's aerosols by their charging

    Science.gov (United States)

    Dimitrov, Vasili; Bar-Nun, Akiva

    2003-12-01

    Titan's haze consists of long chain polymers of pure and N-mixed hydrocarbons (Coustenis et al., 1989, Icarus 80, 54-76, 1991, Icarus 89, 152-167). These polymers have regularly alternating (i.e., conjugated) double/single and triple/single bonds, which open either spontaneously (free aging) or under the action of some external factors (forced aging), the latter being very diverse, e.g., charging, photolysis, radiolysis, thermolysis, chemical effect of environment, etc. An essential of free aging was examined previously (Dimitrov and Bar-Nun, 2002, Icarus 156, 530-538). The main distinction between free and any forced aging is that both of them possess the same thermodynamics while different kinetics, the forced aging in any case being faster, proceeding in different pathways than the free aging. The more extensive is the list of the external effects and the more intensive they are, the faster and more variably the forced aging proceeds. In this paper we quantified the kinetics of forced aging, considering charging of Titan's aerosol population. It was found that forced aging proceeds approximately hundred times faster as compared to the free aging. Various physico-chemical properties of Titan's aerosol material, including coagulation coefficients, depending on particle size and medium conditions, were defined. The comparison of the aging rate, rate of sedimentation and rate of the particle increase proves that Titan's aerosol domain can be subdivided conditionally into two big subdomains. The upper one contains minor portion (95%) of aerosol bulk, which is completely aged, coarsely dispersed particles. We established the border between these subdomains at the altitude Z˜620 km.

  9. Wind-Induced Atmospheric Escape: Titan

    Science.gov (United States)

    Hartle, Richard; Johnson, Robert; Sittler, Edward, Jr.; Sarantos, Menelaos; Simpson, David

    2012-01-01

    Rapid thermospheric flows can significantly enhance the estimates of the atmospheric loss rate and the structure of the atmospheric corona of a planetary body. In particular, rapid horizontal flow at the exobase can increase the corresponding constituent escape rate. Here we show that such corrections, for both thermal and non-thermal escape, cannot be ignored when calculating the escape of methane from Titan, for which drastically different rates have been proposed. Such enhancements are also relevant to Pluto and exoplanets.

  10. Scalable descriptive and correlative statistics with Titan.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, David C.; Pebay, Philippe Pierre

    2008-12-01

    This report summarizes the existing statistical engines in VTK/Titan and presents the parallel versions thereof which have already been implemented. The ease of use of these parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; then, this theoretical property is verified with test runs that demonstrate optimal parallel speed-up with up to 200 processors.

  11. Investigating Titan's Atmospheric Chemistry at Low Temperature with the Titan Haze Simulation Experiment

    Science.gov (United States)

    Sciamma-O'Brien, E. M.; Salama, F.

    2012-12-01

    Titan, Saturn's largest satellite, possesses a dense atmosphere (1.5 bar at the surface) composed mainly of N2 and CH4. The solar radiation and electron bombardment from Saturn's magnetosphere induces a complex organic chemistry between these two constituents leading to the production of more complex molecules and subsequently to solid aerosols. These aerosols in suspension in the atmosphere form the haze layers giving Titan its characteristic orange color. Since 2004, the instruments onboard the Cassini orbiter have produced large amounts of observational data, unraveling a chemistry much more complex than what was first expected, particularly in Titan's upper atmosphere. Neutral, positively and negatively charged heavy molecules have been detected in the ionosphere of Titan, including benzene (C6H6) and toluene (C6H5CH3). The presence of these critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds suggests that PAHs might play a role in the production of Titan's aerosols. The aim of the Titan Haze Simulation (THS) experiment, developed at the NASA Ames COSmIC facility, is to study the chemical pathways that link the simple molecules resulting from the first steps of the N2-CH4 chemistry to benzene, and to PAHs and nitrogen-containing PAHs (PANHs) as precursors to the production of solid aerosols. In the THS experiment, Titan's atmospheric chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma discharge. Due to the short residence time of the gas in the plasma discharge, the THS experiment can be used to probe the first and intermediate steps of Titan's chemistry by injecting different gas mixtures in the plasma. The products of the chemistry are detected and studied using two complementary techniques: Cavity Ring Down Spectroscopy and Time-Of-Flight Mass Spectrometry. Thin tholin deposits are also produced

  12. ELEFUNT test results using Titan Fortran under Ardent UNIX/reg sign/ 2. 0 on the Titan

    Energy Technology Data Exchange (ETDEWEB)

    Cody, W.J.

    1989-03-01

    This report discusses testing of the regular and ''fast'' elementary function libraries supplied with Titan Fortran on the Ardent Titan computer in the Mathematics and Computer Science Division's Advanced Computing Research Facility. Performance tests were conducted using the ELEFUNT suite of programs from the book Software Manual for the Elementary Functions by Cody and Waite. The quality of Titan arithmetic was checked with the MACHAR and PARANOIA programs. 10 refs., 4 tabs.

  13. The global plasma environment of Titan as observed by Cassini Plasma Spectrometer during the first two close encounters with Titan

    OpenAIRE

    Szego, K; Bebesi, Z.; Erdos, G.; L. Foldy; Crary, F.; McComas, D. J.; Young, D. T.; Bolton, S.; Coates, A. J.; A. M. Rymer; Hartle, R. E.; Sittler, E. C.; Reisenfeld, D.; Bethelier, J. J.; Johnson, R. E.

    2005-01-01

    The Cassini spacecraft flew by Titan on October 26, 2004 and December 13, 2004. In both cases it entered the ionosphere of Titan, allowing exploration of its plasma environment. Using observations from the Cassini Plasma Spectrometer (CAPS) and the Cassini magnetometer along the inbound legs of both flybys, we examine Titan's global plasma environment. On both occasions CAPS detected plasma populations distinct from those of the Kronian magnetosphere at about 1 - 1.5 Saturn radii from the moo...

  14. Design, testing, fabrication and launch support of a liquid chemical barium release payload (utilizing the liquid fluorine-barium salt/hydrazine system)

    Science.gov (United States)

    Stokes, C. S.; Smith, E. W.; Murphy, W. J.

    1972-01-01

    A payload was designed which included a cryogenic oxidizer tank, a fuel tank, and burner section. Release of 30 lb of chemicals was planned to occur in 2 seconds at the optimum oxidizer to fuel ratio. The chemicals consisted of 17 lb of liquid fluorine oxidizer and 13 lb of hydrazine-barium salt fuel mixture. The fuel mixture was 17% barium chloride, 16% barium nitrate, and 67% hydrazine, and contained 2.6 lb of available barium. Two significant problem areas were resolved during the program: explosive valve development and burner operation. The release payload was flight tested, from Wallops Island, Virginia. The release took place at an altitude of approximately 260 km. The release produced a luminous cloud which expanded very rapidly, disappearing to the human eye in about 20 seconds. Barium ion concentration slowly increased over a wide area of sky until measurements were discontinued at sunrise (about 30 minutes).

  15. Thermal decomposition of bioactive sodium titanate surfaces

    Science.gov (United States)

    Ravelingien, Matthieu; Mullens, Steven; Luyten, Jan; Meynen, Vera; Vinck, Evi; Vervaet, Chris; Remon, Jean Paul

    2009-09-01

    Alkali-treated orthopaedic titanium surfaces have earlier shown to induce apatite deposition. A subsequent heat treatment under air improved the adhesion of the sodium titanate layer but decreased the rate of apatite deposition. Furthermore, insufficient attention was paid to the sensitivity of titanium substrates to oxidation and nitriding during heat treatment under air. Therefore, in the present study, alkali-treated titanium samples were heat-treated under air, argon flow or vacuum. The microstructure and composition of their surfaces were characterized to clarify what mechanism is responsible for inhibiting in vitro calcium phosphate deposition after heat treatment. All heat treatments under various atmospheres turned out to be detrimental for apatite deposition. They led to the thermal decomposition of the dense sodium titanate basis near the interface with the titanium substrate. Depending on the atmosphere, several forms of Ti yO z were formed and Na 2O was sublimated. Consequently, less exchangeable sodium ions remained available. This pointed to the importance of the ion exchange capacity of the sodium titanate layer for in vitro bioactivity.

  16. Titanate nanotube coatings on biodegradable photopolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S., E-mail: szabolcs.beke@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632, Pécs (Hungary); Scarpellini, A. [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Anjum, F.; Brandi, F. [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy)

    2013-05-01

    Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications.

  17. Titanate nanotube coatings on biodegradable photopolymer scaffolds

    International Nuclear Information System (INIS)

    Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications

  18. Characterization of clouds in Titan's tropical atmosphere

    Science.gov (United States)

    Griffith, C.A.; Penteado, P.; Rodriguez, S.; Le, Mouelic S.; Baines, K.H.; Buratti, B.; Clark, R.; Nicholson, P.; Jaumann, R.; Sotin, C.

    2009-01-01

    Images of Titan's clouds, possible over the past 10 years, indicate primarily discrete convective methane clouds near the south and north poles and an immense stratiform cloud, likely composed of ethane, around the north pole. Here we present spectral images from Cassini's Visual Mapping Infrared Spectrometer that reveal the increasing presence of clouds in Titan's tropical atmosphere. Radiative transfer analyses indicate similarities between summer polar and tropical methane clouds. Like their southern counterparts, tropical clouds consist of particles exceeding 5 ??m. They display discrete structures suggestive of convective cumuli. They prevail at a specific latitude band between 8??-20?? S, indicative of a circulation origin and the beginning of a circulation turnover. Yet, unlike the high latitude clouds that often reach 45 km altitude, these discrete tropical clouds, so far, remain capped to altitudes below 26 km. Such low convective clouds are consistent with the highly stable atmospheric conditions measured at the Huygens landing site. Their characteristics suggest that Titan's tropical atmosphere has a dry climate unlike the south polar atmosphere, and despite the numerous washes that carve the tropical landscape. ?? 2009. The American Astronomical Society.

  19. Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

    Energy Technology Data Exchange (ETDEWEB)

    Brunatova, Tereza; Matej, Zdenek [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic); Oleynikov, Peter [Stockholm University, Dept. of Materials and Environmental Chemistry, SE-106 91 Stockholm (Sweden); Vesely, Josef [Charles University, Faculty of Mathematics and Physics, Dept. of Physics of Materials, Prague (Czech Republic); Danis, Stanislav [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic); Popelkova, Daniela [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague (Czech Republic); Kuzel, Radomir, E-mail: kuzel@karlov.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic)

    2014-12-15

    The structure of titanate nanowires was studied by a combination of powder X-ray diffraction (XRD) and 3D precession electron diffraction. Titania nanowires and titanate nanorods were prepared by heating of titanate nanotubes. The structure of final product depended on heating conditions. Titanium nanotubes heated in air at a temperature of 850 °C decomposed into three phases — Na{sub 2}Ti{sub 6}O{sub 13} (nanorods) and two phases of TiO{sub 2} — anatase and rutile. At higher temperatures the anatase form of TiO{sub 2} transforms into rutile and the nanorods change into rutile nanoparticles. By contrast, in the vacuum only anatase phases of TiO{sub 2} were obtained by heating at 900 °C. The anatase transformation into rutile began only after a longer time of heating at 1000 °C. For the description of anisotropic XRD line broadening in the total powder pattern fitting by the program MSTRUCT a model of nanorods with elliptical base was included in the software. The model parameters — rod length, axis size of the elliptical base, the ellipse flattening parameter and twist of the base could be refined. Variation of particle shapes with temperature was found. - Highlights: • Titanate nanotubes changed to particles of TiO{sub 2} and nanorods of Na{sub 2}Ti{sub 6}O{sub 13} at 850 °C. • With heating time and temperature nanorods transformed to rutile nanoparticles. • X-ray diffraction powder pattern fitting indicated an elliptical shape of nanorod base. • No transition of titanate nanotubes to Na{sub 2}Ti{sub 6}O{sub 13} was found after heating in vacuum. • Heating of titanate nanotubes in vacuum leads to appearance of anatase nanowires.

  20. The crystal growth of barium flouride in aqueous solution

    Science.gov (United States)

    Barone, J. P.; Svrjcek, D.; Nancollas, G. H.

    1983-06-01

    The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25°C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (σ ≈ 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.

  1. Electromagnetic properties of photodefinable barium ferrite polymer composites

    Directory of Open Access Journals (Sweden)

    Olusegun Sholiyi

    2014-07-01

    Full Text Available This article reports the magnetic and microwave properties of a Barium ferrite powder suspended in a polymer matrix. The sizes for Barium hexaferrite powder are 3–6 μm for coarse and 0.8–1.0 μm for the fine powder. Ratios 1:1 and 3:1 (by mass of ferrite to SU8 samples were characterized and analyzed for predicting the necessary combinations of these powders with SU8 2000 Negative photoresist. The magnetization properties of these materials were equally determined and were analyzed using Vibrating Sample Magnetometer (VSM. The Thru, Reflect, Line (TRL calibration technique was employed in determining complex relative permittivity and permeability of the powders and composites with SU8 between 26.5 and 40 GHz.

  2. Thermophysical properties of americium-containing barium plutonate

    International Nuclear Information System (INIS)

    Polycrystalline specimens of americium-containing barium plutonate have been prepared by mixing the appropriate amounts of (Pu0.91Am0.09)O2 and BaCO3 powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. Elastic moduli were determined from longitudinal and shear sound velocities. Debye temperature was also determined from sound velocities and lattice parameter measurements. Thermal conductivity was calculated from measured density at room temperature, literature values of heat capacity and thermal diffusivity measured by laser flash method in vacuum. Thermal conductivity of americium-containing barium plutonate was roughly independent of temperature and registered almost the same magnitude as that of BaPuO3 and BaUO3. (author)

  3. Thermoelectric power of barium up to 8 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Ramani, G.; Divakar, C.; Singh, A.K.

    1987-01-15

    The present measurements indicate that the thermoelectric power (TEP) of barium at room temperature and pressure is 15 ..mu..V K/sup -1/, and decreases with increasing pressure, reaching about 4 ..mu..V K/sup -1/ just before the bcc..-->..hcp transition. The TEP shows a discontinuous increase at the bcc..-->..hcp transition beyond which it continues to decrease with increasing pressure.

  4. Acute barium intoxication following ingestion of soap water solution

    Directory of Open Access Journals (Sweden)

    Nandita Joshi

    2012-01-01

    Full Text Available We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels.

  5. Barium ferrite powders prepared by milling and annealing

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2007-05-01

    Full Text Available Purpose: Microstructure and magnetic properties analysis of barium ferrite powder obtained by milling and heat treatment.Design/methodology/approach: The milling process was carried out in a vibratory mill, which generated vibrations of the balls and milled material inside the container during which their collisions occur. After milling process the powders were annealed in electric chamber furnace. The X-ray diffraction methods were used for qualitative phase analysis of studied powder samples. The distribution of powder particles was determined by a laser particle analyzer. The magnetic hysteresis loops of examined powder material were measured by resonance vibrating sample magnetometer (R-VSM.Findings: The milling process of iron oxide and barium carbonate mixture causes decrease of the crystallite size of involved phases. The X-ray investigations of tested mixture milled for 30 hours and annealed at 950 °C enabled the identification of hard magnetic BaFe12O19 phase and also the presence of Fe2O3 phase in examined material. The Fe2O3 phase is a rest of BaCO3 dissociation in the presence of Fe2O3, which forms a compound of BaFe12O19. The best coercive force (HC for mixture of powders annealed at 950 °C for 10, 20 and 30 hours is 349 kA/m, 366 kA/m and 364 kA/m, respectively. The arithmetic mean of diameter of Fe2O3 and BaCO3 mixture powders after 30 hours of milling is about 6.0 μm.Practical implications: The barium ferrite powder obtained by milling and annealing can be suitable components to produce sintered and elastic magnets with polymer matrix.Originality/value: The results of tested barium ferrite investigations by different methods confirm their utility in the microstructure and magnetic properties analysis of powder materials.

  6. AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

    Science.gov (United States)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien; Gundlach, Jay; Giannini, Francesco; Bain, Sean; Flasar, F. Michael; Hurford, Terry; Anderson, Carrie M.; Merrison, Jon; Adamkovics, Mate; Kattenhorn, Simon A.; Mitchell, Jonathan; Burr, Devon M.; Colaprete, Anthony; Schaller, Emily; Friedson, A. James; Edgett, Kenneth S.; Coradini, Angioletta; Adriani, Alberto; Sayanagi, Kunio M.; Malaska, Michael J.; Morabito, David; Reh, Kim

    2011-01-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments-2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector-AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel 'gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 $715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so within

  7. Role of hexadecapole interaction in proton rich barium isotopes

    International Nuclear Information System (INIS)

    From the systematic analysis of the experimental data on proton rich barium isotopes, it is observed that nuclei in the region z ≥ 50 and N≤82 are the transitional nuclei as they show a shape transition from spherical to deformed shape. An interesting feature of the observed yrast spectra in barium isotopic mass chain is the systematic variation of E2+, E4+ and E6+ excitation energy states from 120Ba to 136Ba. It is observed that these states follow a systematic decreasing trend as move away from 136Ba towards 120Ba. The isotopes 120-128Ba can be taken to be quasi-deformed nuclei having E4+/E2+ ratio larger than 2.7. Based on the systematics of low-lying states and the experimental data of quadrupole moments and B(E2) transition probabilities, the stable barium isotopes range from the approximately spherical 138Ba to l30Ba which is close to the deformed 120-128Ba isotopes. The purpose of the paper is to determine the importance of octupole-octupole and hexadecapole- hexadecapole parts of the two body interaction in reproducing the observed nuclear structure properties of 120-136Ba isotopes

  8. Preparation of Nanoparticles of Barium Ferrite from Precipitation in Microemulsions

    International Nuclear Information System (INIS)

    Magnetic nanoparticles of barium ferrite (BaFe12O19) have been synthesized using a microemulsion mediated process. The aqueous cores of water-in-oil microemulsions were used as constrained microreactors for the precipitation of precursor carbonate and hydroxide particles. These precursors were then calcined at 925 deg. C for 12 h, during which time they were transformed to the hexagonal ferrite. The pH of reaction was varied between 5 and 12, and it was found that the fraction of non-magnetic hematite (α-Fe2O3) in the particles varied with the pH of reaction, thus affecting the magnetic properties of the particles. The same precursor particles were also prepared by bulk co-precipitation reaction for comparison. It was found that the microemulsion derived nanoparticles of barium ferrite had both higher intrinsic coercivity (Hc) and saturation magnetization (σs) than the particles derived from bulk co-precipitation. Particles were analyzed by electron microscopy, X-ray diffraction, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The best barium ferrite particles produced by the microemulsion synthesis method yielded an intrinsic coercivity of 4310 Oe and a saturation magnetization of 60.48 emu/g

  9. Aromatic Structure in Simulates Titan Aerosol

    Science.gov (United States)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  10. Simplified assessment of segmental gastrointestinal transit time with orally small amount of barium

    International Nuclear Information System (INIS)

    Objective: To determine the effectiveness and advantage of small amount of barium in the measurement of gastrointestinal transmission function in comparison with radio-opaque pallets. Methods: Protocal 1: 8 healthy volunteers (male 6, female 2) with average age 40 ± 6.1 were subjected to the examination of radio-opaque pellets and small amount of barium with the interval of 1 week. Protocol 2: 30 healthy volunteers in group 1 (male 8, female 22) with average age 42.5 ± 8.1 and 50 patients with chronic functional constipation in group 2 (male 11, female 39) with average age 45.7 ± 7.8 were subjected to the small amount of barium examination. The small amount of barium was made by 30 g barium dissolved in 200 ml breakfast. After taking breakfast which contains barium, objectives were followed with abdominal X-ray at 4, 8, 12, 24, 48, 72, 96 h until the barium was evacuated totally. Results: Small amount of barium presented actual chyme or stool transit. The transit time of radio-opaque pallets through the whole gastrointestinal tract was significantly shorter than that of barium (37 ± 8 h vs. 47 ± 10 h, P < 0.05) in healthy people. The transit times of barium in constipation patients were markedly prolonged in colon (61.1 ± 22 vs. 37.3 ± 11, P < 0.01) and rectum (10.8 ± 3.7 vs. 2.3 ± 0.8 h, P < 0.01) compared with unconstipated volunteers. Transit times in individual gastrointestinal segments were also recorded by using small amount of barium, which allowed identifying the subtypes of constipation. Conclusion: The small amount barium examination is a convenient and low cost method to provide the most useful and reliable information on the transmission function of different gastrointestinal segments and able to classify the subtypes of slow transit constipation

  11. Barium and Tc-poor S stars: Binary masqueraders among carbon stars

    OpenAIRE

    Jorissen, A; Van Eck, S.

    1997-01-01

    The current understanding of the origin of barium and S stars is reviewed, based on new orbital elements and binary frequencies. The following questions are addressed: (i) Is binarity a necessary condition to produce a barium star? (ii) What is the mass transfer mode (wind accretion or RLOF?) responsible for their formation? (iii) Do barium stars form as dwarfs or as giants? (iv) Do barium stars evolve into Tc-poor S stars? (v) What is the relative frequency of Tc-rich and Tc-poor S stars?

  12. High Resolution Computed Tomography Appearences of late sequelae of Barium Aspiration in an asymptomatic young child

    International Nuclear Information System (INIS)

    Barium aspiration is a well-known complication of upper gastro-intestinal studies. Consequences of aspiration are generally insignificant and leave no permanent changes in the lung parenchyma. However, large quantities of high density barium, if aspirated, lead to silent interstitial changes and fibrosis. High-resolution computed tomography HRCT appearances of lung changes have been demonstrated in adults; few such reports are available in the pediatric literature. We report a case of a child who aspirated barium 3 months before this presentation. The HRCT appearances of barium aspiration are presented with a review of the literature. (author)

  13. Effects of powdered versus liquid barium on the viscosity of fluids used in modified swallow studies

    Energy Technology Data Exchange (ETDEWEB)

    Baron, J.; Alexander, T. [Univ. of Alberta, Dept. of Radiology, Edmonton, Alberta (Canada)

    2003-06-01

    To determine if the viscosity of thickened juice mixtures used in modified barium swallow studies significantly changes with the addition of powdered barium. We also describe a test formulation created using liquid barium, which has a negligible effect on juice viscosity. The viscosities of water and standardized honey- and nectar-consistency juices mixed with different amounts of powdered barium were measured by timing the laminar flow of a given initial hydrostatic head of fluid under gravity though an orifice of fixed diameter. Standardized juices were then mixed with a liquid formulation of barium and with measured quantities of water to produce viscosities that more closely equated with those of the standardized juices. With the addition of powdered barium, viscosity increased in all fluids, most markedly with the nectar-consistency juice. Liquid barium formulations maintained the viscosities of the original thickened juices. Rendering juices radio-opaque with barium powder results in dramatic increases in the viscosity of the resulting mixture and compromises diagnostic accuracy. Liquid barium preparations have the advantage that they can be rapidly and accurately dispensed by syringe, and their use does not significantly increase the viscosity of the preparation. (author)

  14. Exfoliation and thermal transformations of Nb-substituted layered titanates

    DEFF Research Database (Denmark)

    Song, H.; Sjåstad, Anja O.; Fjellvåg, Helmer;

    2011-01-01

    Single-layer Nb-substituted titanate nanosheets of ca. 1 nm thickness were obtained by exfoliating tetrabutylammonium (TBA)-intercalated Nb-substituted titanates in water. AFM images and turbidity measurements reveal that the exfoliated nanosheets crack and corrugate when sonicated. Upon heating,...

  15. BARIUM SULPHATE ABSORPTION AND THE SERUM DIAGNOSIS OF SYPHILIS.

    Science.gov (United States)

    Noguchi, H; Bronfenbrenner, J

    1911-02-01

    The so-called syphilitic antibodies can be removed from a serum by means of absorption with barium sulphate. The removal is due either to an adsorption or a mechanical absorption. The activity of the syphilitic antibodies is thereby unimpaired. The readiness with which the absorption is accomplished with barium sulphate varies considerably with different syphilitic sera. That barium sulphate exerts the same absorbing effect upon non-syphilitic serum components is made evident by the interfering property which the latter manifest in the absorption experiment of the syphilitic antibodies. The selective removal of the serum components, other than the syphilitic antibodies, by means of barium sulphate absorption is, therefore, impossible. On the other hand, a partial removal of these components, with but little removal of the syphilitic antibodies, may be effected when the content of a given serum is poor in syphilitic antibodies and comparatively rich in the indifferent serum components. But this is impossible if the conditions are reversed. The main reasons why some negative syphilitic sera may be so modified by the barium sulphate treatment as to give positive reactions, are explained below, but these apply only to those methods in which inactivated serum is employed. The inactivation reduces the antibody content to about one-fourth to one-fifth of the original. When the serum is very rich in antibodies, this does not affect the result of the fixation test. But when the amount of the antibodies is small, the process of inactivation creates conditions quite unexpected. It may produce such a condition that a given amount of the serum contains, after inactivation, only one or two antibody units, while the other serum components remain undiminished. Here one must not lose sight of the vital fact that these apparently indifferent serum constituents are not at all indifferent in the fixation processes. They may possess affinities which are similar to those of complement

  16. 铝酸钡与氢氧化钡脱硫过程比较%Comparison of Barium Aluminate and Barium Hydroxide Desulfurization Process

    Institute of Scientific and Technical Information of China (English)

    张念炳; 黎志英; 丁彤

    2012-01-01

    The seed precipitation liquor was desulfurized with barium aluminate and barium hydroxide respectively. The desulfurization slag was characterized by XRD analysis, and the desulfurization process was compared. The results show that barium hydroxide exceeds barium aluminate with better desulfurization in terms of effect, speed and duration. In the desulfurization process with barium aluminate, 2BaO · Al2O3 · 5H2O is firstly produced in the reaction of barium aluminate with alkali, and then it reacts with sodium sulfate and sodium carbonate. To compare, Ba(OH)2 · 8H2O directly reacts with sodium sulfate and sodium carbonate in the desulfurization process with barium hydroxide. Both of desulfurization reaction processes can be described with "shrinking core model".%用铝酸钡和氢氧化钡对种分母液进行脱硫试验,对脱硫渣进行XRD分析,并比较脱硫过程.结果表明,氢氧化钡的脱硫效果更好,脱硫完成时间更短,速率更快;铝酸钡先与碱液反应生成2BaO·Al2O3·5H2O,再与硫碱和碳碱反应,而氢氧化钡直接与硫碱和碳碱反应,脱硫过程均可用未反应核模型描述.

  17. Fluvial transport on Titan: formation and evolution of river deltas

    Science.gov (United States)

    Witek, Piotr Przemyslaw; Czechowski, Leszek

    2016-10-01

    The Cassini-Huygens mission provided numerous observations indicating that processes of sediment transport are currently operating on the surface of Titan. We performed numerical simulations of flow and sediment transport on Titan with particular emphasis on formation of sedimentary landforms in Titan's lakes. We compared the morphology and evolution of landforms formed in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. The processes are similar in both environments; in some cases we observed bifurcation of the flow and switching of the active distributaries. Such processes may lead to abandonment of some delta lobes, as hypothesized for the delta observed in Ontario Lacus on Titan. The lower gravity of Titan and higher buoyancy of the most plausible kinds of sediment result in higher efficiency of transport and generally faster evolution of the deltaic deposits. Our results suggest also that the flat, lobate river deltas may form in narrower range of parameters than on Earth.

  18. Charged particle tracking at Titan, and further applications

    Science.gov (United States)

    Bebesi, Zsofia; Erdos, Geza; Szego, Karoly

    2016-04-01

    We use the CAPS ion data of Cassini to investigate the dynamics and origin of Titan's atmospheric ions. We developed a 4th order Runge-Kutta method to calculate particle trajectories in a time reversed scenario. The test particle magnetic field environment imitates the curved magnetic environment in the vicinity of Titan. The minimum variance directions along the S/C trajectory have been calculated for all available Titan flybys, and we assumed a homogeneous field that is perpendicular to the minimum variance direction. Using this method the magnetic field lines have been calculated along the flyby orbits so we could select those observational intervals when Cassini and the upper atmosphere of Titan were magnetically connected. We have also taken the Kronian magnetodisc into consideration, and used different upstream magnetic field approximations depending on whether Titan was located inside of the magnetodisc current sheet, or in the lobe regions. We also discuss the code's applicability to comets.

  19. AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance

    DEFF Research Database (Denmark)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick;

    2012-01-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Explor...

  20. Cassini UVIS observations of Titan nightglow spectra

    Science.gov (United States)

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-12-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120° solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.

  1. Tungsten and barium transport in the internal plasma of hollow cathodes

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2009-06-01

    The effect of tungsten erosion, transport, and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from 8200 h and 30 352 h ion engine wear tests. Erosion and subsequent redeposition of tungsten in the electron emission zone at the downstream end of the insert reduce the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  2. Encouragement from Jupiter for Europe's Titan Probe

    Science.gov (United States)

    1996-04-01

    Huygens will transmit scientific information for 150 minutes, from the outer reaches of Titan's cold atmosphere and all the way down to its enigmatic surface. For comparison, the Jupiter Probe radioed scientific data for 58 minutes as it descended about 200 kilometres into the outer part of the atmosphere of the giant planet. The parachutes controlling various stages of Huygens' descent will rely upon a system for deployment designed and developed in Europe that is nevertheless similar to that used by the Jupiter Probe. The elaborate sequence of operations in Huygens worked perfectly during a dramatic drop test from a stratospheric balloon over Sweden in May 1995, which approximated as closely as possible to events on Titan. The performance of the American Probe at Jupiter renews the European engineers' confidence in their own descent control system, and also in the lithium sulphur-dioxide batteries which were chosen to power both Probes. "The systems work after long storage in space," comments Hamid Hassan, ESA's Project Manager for Huygens. "Huygens will spend seven years travelling to Saturn's vicinity aboard the Cassini Orbiter. The Jupiter Probe was a passenger in Galileo for six years before its release, so there is no reason to doubt that Huygens will work just as well." Huygens will enter the outer atmosphere of Titan at 20,000 kilometres per hour. A heat shield 2.7 metres in diameter will withstand the friction and slow the Probe to a speed at which parachutes can be deployed. The size of the parachute for the main phase of the descent is chosen to allow Huygens to reach the surface in about 2 hours. The batteries powering Huygens will last for about 21/2 hours. Prepared for surprises A different perspective on the Jupiter Probe comes from Jean-Pierre Lebreton, ESA's Project Scientist for Huygens. The results contradicted many preconceptions of the Galileo scientists, particularly about the abundance of water and the structure of cloud layers. Arguments

  3. Are Titan's Lakes Liquid-filled?

    OpenAIRE

    L. Mitchell, K.; Paillou, Philippe; W. Stiles, B.; Zebker, H.; Mitri, G.; Lunine, J. I.; Wall, S.; Lorenz, R. D.; M. C. Lopes, R.; Hensley, S.; R. Stofan, E.; L. Kirk, R.; J. Ostro, S.; Paganelli, F.

    2007-01-01

    SAR imagery obtained during Cassini's T16 Titan fly-by revealed numerous radar-dark features at > ~70° N, interpreted to be lakes [1] on the basis of their low radar reflectivity, morphology and consistency with predictions [2]. Later fly-bys revealed more lakes, and also overlapped with previous scenes, facilitating multi-angle, multi-temporal studies, with several more such opportunities over the coming months. Here we introduce our efforts to understand the nature of the lakes using such s...

  4. High Performance Calcium Titanate Nanoparticle ER Fluids

    Science.gov (United States)

    Wang, Xuezhao; Shen, Rong; Wen, Weijia; Lu, Kunquan

    A type of calcium titanate (CTO) nanoparticles was synthesized by means of wet chemical method [1] without coating on the particles. The CTO/silicone oil ER fluid exhibits excellent electrorheological properties: high shear stress (~50-100 kPa) under dc electric field, a low current density (less than 2μA/cm2 at 5kV/mm), and long term stability against sedimentation. Although there are not special additives in the ER fluids, it is found from the chemical analysis that a trace of alkyl group, hydroxyl group, carbonyl group and some ions is remained in the particles which may dominate the ER response.

  5. Scalable k-means statistics with Titan.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, David C.; Bennett, Janine C.; Pebay, Philippe Pierre

    2009-11-01

    This report summarizes existing statistical engines in VTK/Titan and presents both the serial and parallel k-means statistics engines. It is a sequel to [PT08], [BPRT09], and [PT09] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, and contingency engines. The ease of use of the new parallel k-means engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the k-means engine.

  6. Phase 1 Final Report: Titan Submarine

    Science.gov (United States)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

  7. Rivers on Titan - numerical modelling of sedimentary structures

    Science.gov (United States)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-07-01

    On Titan surface we can expect a few different geomorphological forms, e.g. fluvial valley and river channels. In our research we use numerical model of the river to determine the limits of different fluvial parameters that play important roles in evolution of the rivers on Titan and on Earth. We have found that transport of sediments as suspended load is the main way of transport for Titan [1]. We also determined the range of the river's parameters for which braided river is developed rather than meandering river. Similar, parallel simulations for rivers deltas are presented in [2]. Introduction Titan is a very special body in the Solar System. It is the only moon that has dense atmosphere and flowing liquid on its surface. The Cassini-Huygens mission has found on Titan meandering rivers, and indicated processes of erosion, transport of solid material and its sedimentation. This work is aimed to investigate the similarity and differences between these processes on Titan and the Earth. Numerical model The dynamical analysis of the considered rivers is performed using the package CCHE modified for the specific conditions on Titan. The package is based on the Navier-Stokes equations for depth-integrated two dimensional, turbulent flow and three dimensional convection-diffusion equation of sediment transport. For more information about equations see [1]. Parameters of the model We considered our model for a few different parameters of liquid and material transported by a river. For Titan we consider liquid corresponding to a Titan's rain (75% methane, 25% nitrogen), for Earth, of course, the water. Material transported in rivers on Titan is water ice, for Earth - quartz. Other parameters of our model are: inflow discharge, outflow level, grain size of sediments etc. For every calculation performed for Titan's river similar calculations are performed for terrestrial ones. Results and Conclusions The results of our simulation show the differences in behaviour of the

  8. Activation and waste disposal of the TITAN RFP reactors

    International Nuclear Information System (INIS)

    The TITAN-I lithium self-cooled and TITAN-II aqueous lithium nitrate solution-cooled fusion reactors are based on the reversed-field-pinch (RFP) toroidal confinement concept and operate at high power density with an 18.1 MW/m2 neutron wall loading. These designs were analyzed to study the activation and waste disposal aspects of such high-power density reactors. It was found that because of the use of V-3Ti-1Si (TITAN-I) and reduced activation ferritic steel (TITAN-II) as structural alloys for the first wall, blanket, reflector, and shield components, all the TITAN components except the divertor collector plates can be classified as shallow-land burial (10CFR61 Class C or better) nuclear waste for disposal, provided that the impurity elements, niobium and molybdenum, can be controlled below about 1 and 0.3 appm levels, respectively. The average annual disposal masses were estimated to be 150 and 96 tonne, respectively, for the 1000 MW electric TITAN-I and TITAN-II reactors. This corresponds to about 11% of the total mass in the fusion power core of both reactors. The divertor collector plates are fabricated with W-Re(26 wt%) alloy because of its low particle sputtering properties. The waste disposal ratings of the divertor collector plates in the TITAN-I and TITAN-II reactors, however, are estimated to be factors of 10 and 2, respectively, higher than allowed for Class C disposal. The annual disposal mass of this non-Class C waste is 0.35 tonne, less than 0.4% of the average annual discharge mass for both TITAN-I and TITAN-II reactors. An additional 74 m3 annual discharge of Class C waste containing 14C may be needed for the TITAN-II reactor because of the use of nitrate salt in the aqueous coolant as the tritium breeder. The conclusions derived from the TITAN reactor study are general, and provide strong indications that Class C waste disposal can be achieved for other high-power density approaches to fusion, for example, the tokamak. (orig.)

  9. Microstructure of polymer composite with barium ferrite powder

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2008-12-01

    Full Text Available Purpose: The aim of the paper is the microstructure characterization of commercial BaFe12O19 powder and its composite material in polymer matrix; XRD (X-Ray Diffraction and SEM (Scanning Electron Microscopy methods were applied.Design/methodology/approach: The Rietveld method appeared to be very useful in the verification of the qualitative phase composition and in the determination of phase abundance. Hill and Howard procedure was applied for quantitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The morphology of barium ferrite powders and a fracture surface of the examined composite material was analyzed using the scanning electron microscope.Findings: The X-ray diffraction analysis enabled the identification of BaFe12O19 and Fe2O3 phases in examined material. Basing on Rietveld and Toraya methods the determination of lattice parameters, crystallite size and the lattice distortion was performed. Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles are of irregular shapes and different sizes.Research limitations/implications: Maked researches are limited only to characterization the microstructure of commercial material, because obtained results will be helpful to prepare barium ferrite powders by mechanical alloying and subsequent annealing in the future. As prepared BaFe12O19 powders will be used as the starting material for magnets bonded with polymer material.Originality/value: The obtained results of investigations by different methods of structure analysis confirm their useful in the microstructure analysis of powder materials.

  10. Barium Swallow Findings in the Evaluation of Patients with Dysphagia

    Directory of Open Access Journals (Sweden)

    Amirhosein Hashemi Attar

    2011-05-01

    Full Text Available Background/Objective: Dysphagia is a subjective"nsensation of difficulty in swallowing that has a wide"nrange of etiologies from psychosomatic disorders"nto high grade neoplasms. In this study we evaluated"nbarium swallow findings of patients with dysphagia."nPatients and Methods: We evaluated 200 patients"n(117 men, 83 women; mean age, 49.6 years with"ncomplaint of dysphagia. Fluoroscopic barium"nswallow was done for all the patients and they were"nreviewed for primary peristalsis (presence or absence,"nAbstracts"nS62 Iran J Radiol 2011, 8 (Supp.1"nAbstracts"nimpaired lower esophageal sphincter, esophageal dilatation, delayed emptying of barium, nonperistaltic contractions, stricture and filling defects. Clinical and in some cases endoscopic or manometric follow up was done for all patients."nResults: We had 134 (67% normal barium swallow"nexams with uncomplicated clinical courses. Sixty"nsix patients (33% had abnormal imaging findings"nincluding stricture in 24 patients (12%, filling defect"nin 12 patients (6% and mucosal abnormality in 14"n(7% patients (six cases of mucosal irregularity, three"ncases of mucosal ulceration and five cases of mucosal"nherniation, Bird's beak sign in three patients (1.5%,"ntertiary spasm in six patients (3% and hiatal hernia in"nseven patients (3.5%."nConclusion: In the majority of patients with dysphagia,"nbarium swallow is the only paraclinical study needed"nto plan proper treatment. If radiographic findings are"nequivocal, endoscopy or manometry may be required"nfor more certain diagnosis.

  11. A barium-rich binary central star in Abell 70

    CERN Document Server

    Boffin, Henri M J; Frew, D J; Acker, A; Köppen, J; Moffat, A F J; Parker, Q A

    2011-01-01

    We have found the central star of Abell 70 (PN G038.1-25.4, hereafter A 70) to be a binary consisting of a G8 IV-V secondary and a hot white dwarf. The secondary shows enhanced Ba II and Sr II features, firmly classifying it as a barium star. The nebula is found to have Type-I chemical abundances with helium and nitrogen enrichment, which combined with future abundance studies of the central star, will establish A 70 as a unique laboratory for studying s-process AGB nucleosynthesis.

  12. K-shell fluorescence yields of barium and lanthanum

    International Nuclear Information System (INIS)

    K-shell fluorescence yields for barium and lanthanum have been measured adopting simple 2π geometrical configuration and employing a weak 57Co radioactive source. A scintillation spectrometer with an NaI(Tl) detector of dimensions 44.5 mm diameterx50 mm thickness was employed for the detection and measurement of radiation. The results obtained are in good agreement with the best-fitted values of and also with the other experimental values, indicating that our simple method can be extended to determine fluorescence parameters of high Z materials.

  13. The Kerr nonlinearity of the beta-barium borate crystal

    DEFF Research Database (Denmark)

    Bache, Morten; Guo, Hairun; Zhou, Binbin;

    2013-01-01

    A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond...... experiments BBO is popular because of low dispersion and a high damage threshold. The main attractive property of ultrafast cascading is that the induced cascading nonlinearity nI 2, casc can be negative, i.e. generate a self-defocusing Kerr-like nonlinearity. However, the material Kerr nonlinearity nI 2...

  14. The Kerr nonlinearity of the beta-barium borate crystal

    OpenAIRE

    Bache, Morten; Guo, Hairun; Zhou, Binbin; Zeng, Xianglong

    2013-01-01

    A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond experiments BBO is popular because of low dispersion and a high damage threshold. The main attractive property of ultrafast cascading is that the induced cascading nonlinearity nI 2, casc can be negative, i.e...

  15. Control on Crystal Forms of Ultrafine Barium Carbonate Particles and Study on its Mechanism

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Barium carbonate particles were prepared by using homogeneous precipitation method and co-precipitation method respectively. Through adding different crystalline controlling modifiers, Barium carbonate particles in five different shapes including linear, needle-like, pillarlike, sphere-like and dumbbell-like were synthesized. These particles were characterized by SEM and XRD, and their synthetic mechanism was discussed in this paper.

  16. Investigation on the effects of milling atmosphere on synthesis of barium ferrite/magnetite nanocomposite

    NARCIS (Netherlands)

    Molaei, M.J.; Ataie, A.; Raygan, S.; Picken,n S.J.

    2011-01-01

    In this research, barium ferrite /magnetite nanocomposites synthesized via a mechano-chemical route. Graphite was used in order to reduce hematite content of barium ferrite to magnetite to produce a magnetic nanocomposite. The effects of processing conditions on the powder characteristics were inves

  17. Acute respiratory failure caused by aspiration of high density barium: A case report

    International Nuclear Information System (INIS)

    Accidental aspiration of barium contrast medium during the upper gastrointestinal study can occur in patients with swallowing disorder, especially in the elderly patients. We experienced a case of respiratory failure followed by death within a few hours in 85 year-old patient after barium aspiration

  18. New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus;

    2002-01-01

    Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia......Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia...

  19. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  20. ICES ON TITAN: LABORATORY MEASUREMENTS THAT COMPLEMENT THE HUYGENS PROBE

    Energy Technology Data Exchange (ETDEWEB)

    J. ROBINSON; ET AL

    2000-08-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The composition of the cold bodies in the outer solar system may hold some of the key molecular clues concerning the composition of the prestellax molecular cloud that gave rise to the solar system. We studied the physical chemistry and heterogeneous (gas/surface) reactivity of extraterrestrial ice analogs of the surfaces of Saturn's moon Titan. This program coupled our surface spectroscopic techniques with physical adsorption measurements. We addressed several of the pressing questions regarding Titan such as: Is storage of hydrocarbons in Titan's water ice crust feasible? Do heterogeneous processes influence the atmospheric chemical composition of Titan? Are phase transitions to be expected? These data can be incorporated into photochemical models with the goal of improved modeling of the chemical composition and meteorology of Titan's atmosphere. Titan will be probed by the Cassini-Huygens Mission. Our results on Titan ice analogs can be used to help interpret the mission data.

  1. Likelihood of nitrogen condensation in Titan's present atmosphere

    Science.gov (United States)

    Tokano, Tetsuya%F. AA(Institut für Geophysik und Meteorologie, Universität zu Köln)

    2016-06-01

    Nitrogen condensation is considered to have taken place in Titan's atmosphere in the past when the atmosphere contained much less methane than today or the solar luminosity was smaller. On the other hand, it is not known for sure whether nitrogen condensation takes place on present-day Titan. Vertical temperature profiles in Titan's troposphere obtained Voyager, Huygens and Cassini do not reach the pressure-dependent nitrogen condensation temperature at any location, so that nitrogen condensation was probably not occurring along these profiles at the time of measurements. However, these spacecraft may not have sounded the coldest seasons and areas of Titan since they all took place in the seasons following perihelion. The seasonal cycle of temperature and nitrogen relative humidity in Titan's troposphere has been simulated by a general circulation model in an effort to explore possible areas and seasons of nitrogen condensation on present Titan. In contrast to the upper stratosphere, the seasonal temperature variation in the troposphere is more strongly controlled by Saturn's orbital eccentricity than by Saturn's obliquity. Consequently, the tropospheric temperature globally decreases between the northern vernal equinox and autumnal equinox and reaches the annual minimum around the northern autumnal equinox approximately one season after aphelion. It is possible if not certain that the polar atmosphere between 30 and 40 km altitude temporarily reach the nitrogen condensation temperature in this season and thereby causes liquid nitrogen clouds. Qualitative differences to the more common methane condensation as well as possible impact on Titan's weather are discussed.

  2. Titan LEAF: A Sky Rover Granting Targeted Access to Titan's Lakes and Plains

    Science.gov (United States)

    Ross, Floyd; Lee, Greg; Sokol, Daniel; Goldman, Benjamin; Bolisay, Linden

    2016-10-01

    Northrop Grumman, in collaboration with L'Garde Inc. and Global Aerospace Corporation (GAC), has been developing the Titan Lifting Entry Atmospheric Flight (T-LEAF) sky rover to roam the atmosphere and observe at close quarters the lakes and plains of Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in situ instruments to the surface.T-LEAF is a maneuverable, buoyant air vehicle. Its aerodynamic shape provides its maneuverability, and its internal helium envelope reduces propulsion power requirements and also the risk of crashing. Because of these features, T-LEAF is not restricted to following prevailing wind patterns. This freedom of mobility allows it be commanded to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations.T-LEAF utilizes a variable power propulsion system, from high power at ~200W to low power at ~50W. High power mode uses the propellers and control surfaces for additional mobility and maneuverability. It also allows the vehicle to hover over specific locations for long duration surface observations. Low power mode utilizes GAC's Titan Winged Aerobot (TWA) concept, currently being developed with NASA funding, which achieves guided flight without the use of propellers or control surfaces. Although slower than high powered flight, this mode grants increased power to science instruments while still maintaining control over direction of travel.Additionally, T-LEAF is its own entry vehicle, with its leading edges protected by flexible thermal protection system (f-TPS) materials already being tested by NASA's Hypersonic Inflatable Aerodynamic Decelerator (HIAD) group. This f-TPS technology allows T-LEAF to inflate in space, like HIAD, and then enter the atmosphere fully deployed. This approach accommodates entry velocities from as low as ~1.8 km/s if entering from Titan orbit, up to ~6 km/s if entering directly from Saturn orbit, like the Huygens probe

  3. The atmospheric circulation and methane cycle in the TitanWRF and Titan MITgcm models

    Science.gov (United States)

    Lian, Yuan; Newman, Claire E.; Richardson, Mark I.

    2016-10-01

    We use the TitanWRF and Titan MITgcm to simulate the formation of stratospheric superrotation on Titan. The stratospheric wind speed reaches 180 m/s around both solstices. The MITgcm results appear similar to those from Titan WRF (Newman et al., 2011). However, despite the similar physics parameterizations such as radiative transfer and PBL mixing, the MITgcm produces a consistent minimum (about 5 to 15m/s depending on the season) near 50km above the surface. This result is comparable to the wind profile obtained by Huygens, though the observed wind minimum was between 75km and 80km above the surface. Attempts have been made to investigate what produces the wind minimum, e.g., turning off the diurnal cycle and removing surface thermal inertia. The wind minimum persists despite the effort, suggesting the feature may originate from interactions between zonal wind and downward propagating waves. We further examine the effect of topography on the wind structure. The stratospheric superrotation in these simulations is significantly slower than that in the simulations without topography, with maximum speed of 110m/s as opposed to previously simulated 180m/s. The wind minimum near 50km, however, still exists in the MITgcm. Also, results suggest that the near surface winds are primarily guided by topography, and are less affected by solar heating on the surface. Another distinct result, compared to the cases without topography in both TitanWRF and the MITgcm, is that the near surface winds in the equatorial region exhibit strong eastward components, which may help to explain the combination of dune orientations and transport directions inferred from imaging. Lastly, we introduce an active methane cycle using a simplified Betts-Miller scheme (similar to Mitchell et al, 2009) to represent moist convection associated with the methane cycle in the troposphere. We will explore the impact of the new scheme on the methane cycle, and compare its realism to that of the large

  4. Progress at the TITAN-EBIT

    Energy Technology Data Exchange (ETDEWEB)

    Klawitter, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 Canada and Max Planck Institut für Kernphysik, 69117 Heidelberg (Germany); Alanssari, M.; Frekers, D. [Institut für Kernphysik, Westfälische Wilhelms-Universität, 48149 Münster (Germany); Chowdhury, U.; Gwinner, G. [Department of Physics, University of Manitoba, R3T 2N2, Winnipeg (Canada); Chaudhuri, A.; Grossheim, A.; Kwiatkowski, A. A.; Leach, K.; Schultz, B. E.; Dilling, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 (Canada); López-Urrutia, J. R. Crespo [Max Planck Institut für Kernphysik, 69117 Heidelberg (Germany); Ettenauer, S. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Gallant, A. T.; Macdonald, T. D. [TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 Canada and Department of Physics and Astronomy, University of British Columbia, Vancouver BC, V6T 1Z1 (Canada); Lennarz, A. [TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 Canada and Institut für Kernphysik, Westfälische Wilhelms-Universität, 48149 Münster (Germany); Simon, M. C. [Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, 1090 Vienna (Austria); Seeraji, S.; Andreoiu, C. [Department of Chemistry, Simon Fraser University, Burnaby BC, V6T 2A3 (Canada)

    2015-01-09

    Precision mass measurements of short-lived isotopes provide insight into a wide array of physics, including nuclear structure, nucleosynthesis, and tests of the Standard Model. The precision of Penning trap mass spectrometry (PTMS) measurements is limited by the lifetime of the isotopes of interest, but scales proportionally with their charge state q, making highly charged ions attractive for mass measurements of nuclides far from stability. TITAN, TRIUMF's Ion Trap(s) for Atomic and Nuclear science, is currently the only setup in the world coupling an EBIT to a rare isotope facility for the purpose of PTMS. Charge breeding ions for Penning trap mass spectrometry, however, entails specific set of challenges. To make use of its potential, efficiencies have to be high, breeding times have to be short and the ion energy spread has to be small. An overview of the TITAN facility and charge-breeding program is given, current and future developments are highlighted and some selected results are presented.

  5. Low Temperature Spin Structure of Gadolinium Titanate

    Science.gov (United States)

    Javanparast, Behnam; McClarty, Paul; Gingras, Michel

    2012-02-01

    Many rare earth pyrochlore oxides exhibit exotic spin configurations at low temperatures due to frustration. The nearest neighbor coupling between spins on the corner-sharing tetrahedral network generate geometrical magnetic frustration. Among these materials, gadolinium titanate (Gd2Ti2O7) is of particular interest. Its low temperature ordered phases are not yet understood theoretically. Bulk thermal measurements such as specific heat and magnetic susceptibility measurements find two phase transitions in zero external field, in agreement with simple mean field calculations. However, recent neutron scattering experiments suggest a so-called 4-k spin structure for intermediate phase and a so called canted 4-k structure for lower temperature phase that does not agree with either mean-field theory or Monte Carlo simulation which find the 1-k state and Palmer-Chalker state respectively as the lowest free energy configuration for those phases. In our work, we study the 4-k structure in detail and present a new phase diagram for dipolar Heisenberg spins on a pyrochlore lattice, certain portions of which describe gadolinium titanate.

  6. TEAM – Titan Exploration Atmospheric Microprobes

    Science.gov (United States)

    Nixon, Conor; Esper, Jaime; Aslam, Shahid; Quilligan, Gerald

    2016-10-01

    The astrobiological potential of Titan's surface hydrocarbon liquids and probable interior water ocean has led to its inclusion as a destination in NASA's "Ocean Worlds" initiative, and near-term investigation of these regions is a high-level scientific goal. TEAM is a novel initiative to investigate the lake and sea environs using multiple dropsondes –scientific probes derived from an existing cubesat bus architecture (CAPE – the Cubesat Application for Planetary Exploration) developed at NASA GSFC. Each 3U probe will parachute to the surface, making atmospheric structure and composition measurements during the descent, and photographing the surface – land, shoreline and seas - in detail. TEAM probes offer a low-cost, high-return means to explore multiple areas on Titan, yielding crucial data about the condensing chemicals, haze and cloud layers, winds, and surface features of the lakes and seas. These microprobes may be included on a near-term New Frontiers class mission to the Saturn system as additional payload, bringing increased scientific return and conducting reconnaissance for future landing zones. In this presentation we describe the probe architecture, baseline payload, flight profile and the unique engineering and science data that can be returned.

  7. Processing ISS Images of Titan's Surface

    Science.gov (United States)

    Perry, Jason; McEwen, Alfred; Fussner, Stephanie; Turtle, Elizabeth; West, Robert; Porco, Carolyn; Knowles, Ben; Dawson, Doug

    2005-01-01

    One of the primary goals of the Cassini-Huygens mission, in orbit around Saturn since July 2004, is to understand the surface and atmosphere of Titan. Surface investigations are primarily accomplished with RADAR, the Visual and Infrared Mapping Spectrometer (VIMS), and the Imaging Science Subsystem (ISS) [1]. The latter two use methane "windows", regions in Titan's reflectance spectrum where its atmosphere is most transparent, to observe the surface. For VIMS, this produces clear views of the surface near 2 and 5 microns [2]. ISS uses a narrow continuum band filter (CB3) at 938 nanometers. While these methane windows provide our best views of the surface, the images produced are not as crisp as ISS images of satellites like Dione and Iapetus [3] due to the atmosphere. Given a reasonable estimate of contrast (approx.30%), the apparent resolution of features is approximately 5 pixels due to the effects of the atmosphere and the Modulation Transfer Function of the camera [1,4]. The atmospheric haze also reduces contrast, especially with increasing emission angles [5].

  8. Titan's corona: The contribution of exothermic chemistry

    Science.gov (United States)

    De La Haye, V.; Waite, J. H.; Cravens, T. E.; Nagy, A. F.; Johnson, R. E.; Lebonnois, S.; Robertson, I. P.

    2007-11-01

    The contribution of exothermic ion and neutral chemistry to Titan's corona is studied. The production rates for fast neutrals N 2, CH 4, H, H 2, 3CH 2, CH 3, C 2H 4, C 2H 5, C 2H 6, N( 4S), NH, and HCN are determined using a coupled ion and neutral model of Titan's upper atmosphere. After production, the formation of the suprathermal particles is modeled using a two-stream simulation, as they travel simultaneously through a thermal mixture of N 2, CH 4, and H 2. The resulting suprathermal fluxes, hot density profiles, and energy distributions are compared to the N 2 and CH 4 INMS exospheric data presented in [De La Haye, V., Waite Jr., J.H., Johnson, R.E., Yelle, R.V., Cravens, T.E., Luhmann, J.G., Kasprzak, W.T., Gell, D.A., Magee, B., Leblanc, F., Michael, M., Jurac, S., Robertson, I.P., 2007. J. Geophys. Res., doi:10.1029/2006JA012222, in press], and are found insufficient for producing the suprathermal populations measured. Global losses of nitrogen atoms and carbon atoms in all forms due to exothermic chemistry are estimated to be 8.3×10 Ns and 7.2×10 Cs.

  9. Alluvial Fan Morphology, distribution and formation on Titan

    Science.gov (United States)

    Birch, S. P. D.; Hayes, A. G.; Howard, A. D.; Moore, J. M.; Radebaugh, J.

    2016-05-01

    Titan is a hydrologically active world, with dozens of alluvial fans that are evidence of sediment transport from high to low elevations. However, the distribution and requirements for the formation of fans on Titan are not well understood. We performed the first global survey of alluvial fans on Titan using Cassini Synthetic Aperture Radar (SAR) data, which cover 61% of Titan's surface. We identified 82 fans with areas ranging from 28 km2 to 27,000 km2. A significant fraction (∼60%) of the fans are restricted to latitudes of ±50-80°, suggesting that fluvial sediment transport may have been concentrated in the near-polar terrains in the geologically recent past. The density of fans is also found to be correlated with the latitudes predicted to have the highest precipitation rates by Titan Global Circulation Models. In equatorial regions, observable fans are not generally found in proximity to dune fields. Such observations suggest that sediment transport in these areas is dominated by aeolian transport mechanisms, though with some degree of recent equatorial fluvial activity. The fan area-drainage area relationship on Titan is more similar to that on Earth than on Mars, suggesting that the fans on Titan are smaller than what may be expected, and that the transport of bedload sediment is limited. We hypothesize that this has led to the development of a coarse gravel-lag deposit over much of Titan's surface. Such a model explains both the morphology of the fans and their latitudinal concentration, yielding insight into the sediment transport regimes that operate across Titan today.

  10. Poster 14: Explorer of Enceladus and Titan (E2T)

    Science.gov (United States)

    Mitri, Giuseppe; Tobie, Gabriel; Postberg, Frank; Soderblom, Jason M.; Wurz, Peter; Barnes, Jason W.; Berga, Marco; Coustenis, Athena; D'Ottavio, Andrea Hayes, Alexander G.; Hayne, Paul O.; Lebreton, Jean-Pierre; Lorenz, Ralph D.; Martelli, Andrea; Petropoulos, Anastassios E.; Yen, Chen-wan L.; Reh, Kim R.; Sotin, Christophe; Srama, Ralf; Tortora, Paolo

    2016-06-01

    The NASA-ESA Cassini-Huygens mission has revealed Titan and Enceladus to be two of the most enigmatic worlds in the Solar System. Titan, with its organically rich and dynamic atmosphere and geology, and Enceladus, with its active plume, both harboring subsurface oceans, are prime environments in which to investigate the conditions for the emergence of life and the habitability of Ocean Worlds. Explorer of Enceladus and Titan (E2T) is dedicated to investigating the evolution and habitability of these Saturnian satellites and will be proposed as a medium-class mission led by ESA in collaboration with NASA in response to ESA's M5 Call. E2T has a focused payload that will provide in-situ sampling and high-resolution imaging during multiple flybys of Enceladus and Titan using a solar-electric powered spacecraft in orbit around Saturn. The E2T mission will provide high-resolution mass spectroscopy of the plume emanating from Enceladus' south polar terrain (SPT) and of Titan's upper atmosphere as well as high-resolution IR imaging of the plume and the source fractures on Enceladus' SPT, and it will detail Titan's geomorphology at 50-100 m resolution. The E2T mission has three scientific goals: 1) Investigate the origin and evolution of volatile-rich icy worlds by examining both Enceladus and Titan, 2) Investigate the habitability and potential for life in ocean worlds on both Enceladus and Titan and 3) Investigate Titan as an Earth-like world with an evolving climate and landscape. These investigations will be accomplished by measuring the nature, abundance and isotopic properties of solid- and vapor-phase species in Enceladus' plume and Titan's upper atmosphere. E2T's high-resolution time-of-flight mass spectrometers will enable us to untangle the ambiguities left by Cassini regarding the identification of low-mass organic species, identify high-mass organic species for the first time, further constrain trace species such as the noble gases, and clarify the evolution of

  11. Ambipolar escape from Venus, Mars and Titan, and negative ions at Titan

    Science.gov (United States)

    Coates, Andrew

    2016-07-01

    Ionospheric photoelectrons are a natural product of the photo-ionisation of planetary atmospheres. Their energy spectrum is distinctive and depends on the solar spectrum in the EUV and X-ray region. On production, the energetic electrons move along the magnetic field (open or draped), setting up an ambipolar electric field which can extract ions. This provides an escape mechanism similar to Earth's 'polar wind'. As these objects are unmagnetised, this produces an extended escape mechanism over the whole sunlit ionosphere. Here, we review recent measurements of photoelectrons far from the parent objects at Venus, Mars and Titan, from Venus Express, Mars Express, Maven and Cassini, and discuss similarities and related escape rates. We also review the pioneering observations of the remarkably heavy negative ions discovered in Titan's ionosphere.

  12. Síntese e caracterização da cerâmica PZT dopada com íons bário Synthesis and characterization of barium-doped PZT ceramics

    Directory of Open Access Journals (Sweden)

    G. Gasparotto

    2003-04-01

    Full Text Available Pós de titanato zirconato de chumbo (PZT puros e dopados com bário foram obtidos pelo método de precursores poliméricos, conformados uniaxialmente, na forma de cilindros, utilizando 15 MPa, e prensados isostaticamente à 210MPa. Com o objetivo de estudar o comportamento de sinterização os compactos foram divididos em dois lotes. Sendo um sinterizado em um forno acoplado a um dilatômetro até a temperatura de 1300 °C e o outro sinterizado em forno tipo mufla, em sistema fechado, na temperatura de 1100 °C por 4 horas. Verificou-se que a adição do íon bário influencia na cinética de sinterização, na densificação final, na microestrutura e nas propriedades elétricas da cerâmica. A adição de bário aumenta a concentração da fase tetragonal no PZT, em função da substituição do chumbo por bário na rede perovskita. As amostras dopadas com concentrações maiores que 5,0 mol % em bário apresentaram segregação de PbO no contorno de grão, inibindo seu crescimento.Pure and barium doped lead zirconate titanate powders were obtained by the polymeric precursor method, uniaxially conformed in cylinders form using 15 MPa and pressing isostatically at 210 MPa. In order to study the sintering behaviour, the compacts were divided in two parts. One part was sintered in a dilatometer furnace till 1300 °C and the other one sintered in muffle furnace in the temperature of 1100 °C for 4 hours. It was verified that the addition of barium influences on the sintering kinetics, on the final density, microstructure and electric properties of the ceramics. The addition of barium increases the concentration of the tetragonal phase of PZT due to the substitution of lead by barium in the perovskite lattice. The samples doped with barium concentrations higher than 5.0 mol % leads to the segregation of PbO in the grain boundary, inhibiting grain growth.

  13. Ruthenium and hafnium abundances in giant and dwarf barium stars

    CERN Document Server

    Allen, D M

    2007-01-01

    We present abundances for Ru and Hf, compare them to abundances of other heavy elements, and discuss the problems found in determining Ru and Hf abundances with laboratory gf-values in the spectra of barium stars. We determined Ru and Hf abundances in a sample of giant and dwarf barium stars, by the spectral synthesis of two RuI (4080.574A and 4757.856A) and two HfII (4080.437A and 4093.155A) transitions. The stellar spectra were observed with FEROS/ESO, and the stellar atmospheric parameters lie in the range 4300 < Teff/K < 6500, -1.2 < [Fe/H] <= 0 and 1.4 <= log g < 4.6. The HfII 4080A and the RuI 4758A observed transitions result in a unreasonably high solar abundance, given certain known uncertainties, when fitted with laboratory gf-values. For these two transitions we determined empirical gf-values by fitting the observed line profiles of the spectra of the Sun and Arcturus. For the sample stars, this procedure resulted in a good agreement of Ru and Hf abundances given by the two availa...

  14. Materials Synthesis Of Barium Hexa ferrite Used Local Natural Resources

    International Nuclear Information System (INIS)

    The magnetic materials of barium hexa ferrites, Ba O.6Fe2O3 successfully synthesized by powder metallurgy method used local natural resources from materials waste of steel fabrication (HSM, CRM), waste of polymer fabrication (LK) as well as iron sands (PBA). These waste as well as iron sands were the main resources of iron oxide, Fe2O3. The barium oxide used in this experiments are from BaCO3 product of Merck, and BaCO4 which is commercially available in the market as barite. Phase identification by x-ray diffraction technique show the synthesized magnetic materials are agreed with the available commercial product, (SUMI). The energy product maximum (BH)max measured by vibrating sample magnetometer (VSM) for the samples used HSM-, CRM- and BaCO3 as basic materials are 1.141 MGOe and 1.136 MGOe while SUMI is 1.142 MGOe. However for the samples made from LK-, PBA- used of BaCO3 or CRM- with barite, the energy product maximum (BH)max are relatively lower than commercial product

  15. Microstructure of composite material with powders of barium ferrite

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2006-04-01

    Full Text Available Purpose: The aim of the present work is the microstructure characterization of commercial powder BaFe12O19 (as-prepared and composite material with BaFe12O19 powders and polymer matrix, using XRD (X-Ray Diffraction and SEM (Scanning Electron Microscopy methods.Design/methodology/approach: The morphology of barium ferrite powders and a fracture surface of the examined composite material was realized by using the scanning electron microscope. The methods of X-ray diffraction were used for the qualitative phase analysis. The parameters of diffraction line profiles were determined by PRO-FIT Toraya procedure.Findings: The X-ray diffraction analysis permitted on identification the BaFe12O19 and Fe2O3 phases in an examined material. Basing on Toraya method is determination of: lattice parameters, crystallite size (D and the lattice distortion (. Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles have irregular shapes and dimensions.Research limitations/implications: For future research the X-ray analysis should be performed by the Rietveld method, which allows to characterization the microstructure of tested material and verification of its qualitative phase composition.Originality/value: The applied Toraya method of structure analysis appeared to be very useful in the microstructure analysis.

  16. Thermal expansion behaviour of barium and strontium zirconium phosphates

    Indian Academy of Sciences (India)

    P Srikari Tantri; K Geetha; A M Umarji; Sheela K Ramasesha

    2000-12-01

    Ba1.5–SrZr4P5SiO24 compounds with = 0, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5, belonging to the low thermal expansion NZP family were synthesized by the solid state reaction method. The XRD pattern could be completely indexed with respect to R$\\bar{3}$ space group indicating the ordering of vacancy at the divalent cation octahedral sites. The microstructure and bulk thermal expansion coefficient from room temperature to 800°C of the sintered samples have been studied. All the samples show very low coefficient of thermal expansion (CTE), with = 0 samples showing negative expansion. A small substitution of strontium in the pure barium compound changes the sign of CTE. Similarly, = 1.5 sample (pure strontium) shows a positive CTE and a small substitution of barium changes its sign. = 1.0 and 1.25 samples have almost constant CTE over the entire temperature range. The low thermal expansion of these samples can be attributed to the ordering of the ions in the crystal structure of these materials.

  17. [alpha]-Decay damage effects in curium-doped titanate ceramic containing sodium-free high-level nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, Hisayoshi; Matsumoto, Seiichiro; Tsuboi, Takashi; Hashimoto, Masaaki; Togashi, Yoshihiro; Kanazawa, Hiroyuki (Japan Atomic Energy Research Inst., Ibaraki (Japan)); Stewart, M.W.A.; Vance, E.R.; Hart, K.P.; Ball, C.J. (Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales (Australia). Lucas Heights Research Labs.); White, T.J.

    1994-09-01

    A polyphase titanate ceramic incorporating sodium-free simulated high-level nuclear waste was doped with 0.91 wt% of [sup 224]Cm to accelerate the effects of long-term self-irradiation arising from [alpha] decays. The ceramic included three main constituent minerals: hollandite, perovskite, and zirconolite, with some minor phases. Although hollandite showed the broadening of its X-ray diffraction lines and small lattice parameter changes during damage in growth, the unit cell was substantially unaltered. Perovskite and zirconolite, which are the primary hosts of curium, showed 2.7% and 2.6% expansions, respectively, of their unit cell volumes after a dose of 12 [times] 10[sup 17] [alpha] decays[center dot]g[sup [minus]1]. Volume swelling due to damage in growth caused an exponential (almost linear) decrease in density, which reached 1.7% after a dose of 12.4 [times] 10[sup 17] [alpha] decays[center dot]g[sup [minus]1]. Leach tests on samples that had incurred doses of 2.0 [times] 10[sup 17] and 4.5 [times] 10[sup 17] [alpha] decays[center dot]g[sup [minus]1] showed that the rates of dissolution of cesium and barium were similar to analogous leach rates from the equivalent cold ceramic, while strontium and calcium leach rates were 2--15 times higher. Although the cerium, molybdenum, strontium, and calcium leach rates in the present material were similar to those in the curium-doped sodium-bearing titanate ceramic reported previously, the cesium leach rate was 3--8 times lower.

  18. Low Permeation Envelope Material Development for Titan Aerobot Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerobot vehicles for missions on Titan require envelope materials that are strong, light and durable. In particular they must be able to withstand flexing at liquid...

  19. Aerosols optical propertites in Titan's Detached Haze Layer

    Science.gov (United States)

    Seignovert, Benoît; Rannou, Pascal; Lavvas, Panayotis; Cours, Thibaud; West, Robert A.

    2016-06-01

    Titan's Detached Haze Layer (DHL) first observed in 1983 by Rages and Pollack during the Voyager 2 [1] is a consistent spherical haze feature surrounding Titan's upper atmosphere and detached from the main haze. Since 2005, the Imaging Science Subsystem (ISS) instrument on board the Cassini mission performs a continuous survey of the Titan's atmosphere and confirmed its persistence at 500 km up to the equinox (2009) before its drop and disappearance in 2012 [2]. Previous analyses showed, that this layer corresponds to the transition area between small spherical aerosols and large fractal aggregates and play a key role in the aerosols formation in Titan's atmosphere [3-5]. In this study we perform UV photometric analyses on ISS observations taken from 2005 to 2007 based on radiative transfer inversion to retrieve aerosols particles properties in the DHL (bulk and monomer size, fractal dimension and local density).

  20. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors

  1. Neptune and Titan Observed with Keck Telescope Adaptive Optics

    Energy Technology Data Exchange (ETDEWEB)

    Max, C.E.; Macintosh, B.A.; Gibbard, S.; Gavel, D.T.; Roe, H.; De Pater, I.; Ghez, A.M.; Acton, S.; Wizinowich, P.L.; Lai, O.

    2000-05-05

    The authors report on observations taken during engineering science validation time using the new adaptive optics system at the 10-m Keck II Telescope. They observe Neptune and Titan at near-infrared wavelengths. These objects are ideal for adaptive optics imaging because they are bright and small, yet have many diffraction-limited resolution elements across their disks. In addition Neptune and Titan have prominent physical features, some of which change markedly with time. They have observed infrared-bright storms on Neptune, and very low-albedo surface regions on Titan, Saturn's largest moon, Spatial resolution on Neptune and Titan was 0.05-0.06 and 0.04-0.05 arc sec, respectively.

  2. Biologically Enhanced Energy and Carbon Cycling on Titan?

    CERN Document Server

    Schulze-Makuch, D

    2005-01-01

    With the Cassini-Huygens Mission in orbit around Saturn, the large moon Titan, with its reducing atmosphere, rich organic chemistry, and heterogeneous surface, moves into the astrobiological spotlight. Environmental conditions on Titan and Earth were similar in many respects 4 billion years ago, the approximate time when life originated on Earth. Life may have originated on Titan during its warmer early history and then developed adaptation strategies to cope with the increasingly cold conditions. If organisms originated and persisted, metabolic strategies could exist that would provide sufficient energy for life to persist, even today. Metabolic reactions might include the catalytic hydrogenation of photochemically produced acetylene, or involve the recombination of radicals created in the atmosphere by UV radiation. Metabolic activity may even contribute to the apparent youth, smoothness, and high activity of the surface of Titan via biothermal energy.

  3. The structure of Titan's wake from plasma wave observations

    Science.gov (United States)

    Gurnett, D. A.; Kurth, W. S.; Scarf, F. L.

    1982-01-01

    The electron density profile inferred from plasma wave emissions detected during the Voyager 1 flyby of Titan exhibits three distinct peaks with densities of about 40/cu cm, the first peak corresponding to the entry into the magnetic tail, the second corresponding to the neutral sheet crossing from the northern to the southern tail lobe, and the third corresponding to the outbound exit from the tail. Large depressions in the magnetic field strength are observed coincident with each of the density peaks, indicating that a dense plume of plasma is being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn. The 8600 K plasma temperature estimated suggests that the plasma originates from the ionosphere of Titan, probably forming a plasma plume with a theta or H cross section extending downstream from Titan.

  4. The TITAN reversed-field-pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors.

  5. Phase IV Simulant Testing of Monosodium Titanate Adsorption Kinetics

    International Nuclear Information System (INIS)

    The Salt Disposition Systems Engineering Team identified the adsorption kinetics of actinides and strontium onto monosodium titanate (MST) as a technical risk in several of the processing alternatives selected for additional evaluation in Phase III of their effort

  6. Morphology of river deltas on Titan and Earth

    Science.gov (United States)

    Witek, Piotr; Czechowski, Leszek

    2016-07-01

    The Cassini-Huygens mission is entering its final phase. The landing of Huygens on Titan and flybys performed by the Cassini probe during the last ten years revolutionized our knowledge about that moon, revealing a complex fluvio-lacustrine environment. Despite significant differences in composition, temperature and gravity, the processes of sediment transport and deposition are similar on Earth and Titan. We performed numerical simulations of development of river deltas in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. We found that evolution of deltaic deposits is more rapid on Titan due to higher efficiency of transport, but the flat, lobate river deltas may form in narrower range of parameters than on Earth. Our results help in understanding the evolution of sedimentary deposits and may partially explain the paucity of river deltas in Titan's lakes.

  7. The influence of Titan on Saturn kilometric radiation

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2010-02-01

    Full Text Available Previous studies have shown that the occurrence probability of Saturn Kilometric Radiation (SKR appears to be influenced by the local time of Titan. Using a more extensive set of data than the original study, we confirm the correlation of higher occurrence probability of SKR when Titan is located near local midnight. In addition, the direction finding capability of the Cassini Radio Plasma Wave instrument (RPWS is used to determine if this radio emission emanates from particular source regions. We find that most source regions of SKR are located in the mid-morning sector of local time even when Titan is located near midnight. However, some emission does appear to have a source in the Saturnian nightside, consistent with electron precipitation from field lines that have recently mapped to near Titan.

  8. Low Permeation Envelope Material Development for Titan Aerobot Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerobot vehicles for missions on Titan require envelope materials that are strong, light and durable. Unlike terrestrial balloon materials, these must be able to...

  9. HST observations of the limb polarization of Titan

    CERN Document Server

    Bazzon, Andreas; Buenzli, Esther

    2014-01-01

    Titan is an excellent test case for detailed studies of the scattering polarization from thick hazy atmospheres. We present the first limb polarization measurements of Titan, which are compared as a test to our limb polarization models. Previously unpublished imaging polarimetry from the HST archive is presented which resolves the disk of Titan. We determine flux-weighted averages of the limb polarization and radial limb polarization profiles, and investigate the degradation and cancelation effects in the polarization signal due to the limited spatial resolution of our observations. Taking this into account we derive corrected values for the limb polarization in Titan. The results are compared with limb polarization models, using atmosphere and haze scattering parameters from the literature. In the wavelength bands between 250 nm and 2000 nm a strong limb polarization of about 2-7 % is detected with a position angle perpendicular to the limb. The fractional polarization is highest around 1 micron. As a first ...

  10. Titan Submarine: Exploring the Depths of Kraken Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Titan is unique in the outer solar system in that it is the only one of the bodies outside the Earth with liquid lakes and seas on its surface. The Titanian seas,...

  11. Amphibious Quadcopter Swarm for the Exploration of Titan

    Science.gov (United States)

    Rajguru, A.; Faler, A. C.; Franz, B.

    2014-06-01

    This is a proposal for a low mass and cost effective mission architecture consisting of an amphibious quadcopter swarm flight vehicle system for the exploration of Titan's liquid methane lake, Ligeia Mare. The paper focuses on the EDL and operations.

  12. A New Titan Atmospheric Model for Mission Engineering Applications

    Science.gov (United States)

    Waite, J. H.; Bell, J. M.; Lorenz, R.; Achterberg, R.; Flasar, F. M.

    2012-03-01

    Titan’s polar regions and hydrocarbon lakes are of interest for future exploration. This paper describes a new engineering model of Titan’s atmospheric structure with particular reference to the proposed Titan Mare Explorer mission.

  13. A Numerical Study of Micrometeoroids Entering Titan's Atmosphere

    Science.gov (United States)

    Templeton, M.; Kress, M. E.

    2011-01-01

    A study using numerical integration techniques has been performed to analyze the temperature profiles of micrometeors entering the atmosphere of Saturn s moon Titan. Due to Titan's low gravity and dense atmosphere, arriving meteoroids experience a significant cushioning effect compared to those entering the Earth's atmosphere. Temperature profiles are presented as a function of time and altitude for a number of different meteoroid sizes and entry velocities, at an entry angle of 45. Titan's micrometeoroids require several minutes to reach peak heating (ranging from 200 to 1200 K), which occurs at an altitude of about 600 km. Gentle heating may allow for gradual evaporation of volatile components over a wide range of altitudes. Computer simulations have been performed using the Cassini/Huygens atmospheric data for Titan. Keywords micrometeoroid Titan atmosphere 1 Introduction On Earth, incoming micrometeoroids (100 m diameter) are slowed by collisions with air molecules in a relatively compact atmosphere, resulting in extremely rapid deceleration and a short heating pulse, often accompanied by brilliant meteor displays. On Titan, lower gravity leads to an atmospheric scale height that is much larger than on Earth. Thus, deceleration of meteors is less rapid and these particles undergo more gradual heating. This study uses techniques similar to those used for Earth meteoroid studies [1], exchanging Earth s planetary characteristics (e.g., mass and atmospheric profile) for those of Titan. Cassini/Huygens atmospheric data for Titan were obtained from the NASA Planetary Atmospheres Data Node [4]. The objectives of this study were 1) to model atmospheric heating of meteoroids for a range of micrometeor entry velocities for Titan, 2) to determine peak heating temperatures and rates for micrometeoroids entering Titan s atmosphere, and 3) to create a general simulation environment that can be extended to incorporate additional parameters and variables, including different

  14. Hydrothermal synthesis of sodium titanate nanotubes

    International Nuclear Information System (INIS)

    From suspension of nanoparticles TiO2 in concentrated water solution of NaOH were prepared by hydrothermal synthesis sodium titanates particles with different shapes. Influence of synthesis duration under temperature 180 grad C on the change of particles shapes was observed. The result of experiment showed that one day synthesis resulted to obtained product with high content of nanotubes, but the extension of this period led to the transformation of product's shape into stripes. From the results of experiment follows that as a precursor for TiO2 nanotubes preparation may be used only products of hydrothermal synthesis, which duration of pressure synthesis was not longer than 24 hours. (authors)

  15. Thermal expansion in lead zirconate titanate

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The volume anomalies with temperature variations in tin-modified lead zirconate titanate ceramics are investigated. Experimental results show that the volume changes are related to the phase transitions induced with temperature. The magnitude and orientation of crystal volume changes are dependent on the particular phase transition. When antiferroelectrics is transformed to ferroelectrics or paraelectrics the volume expands. Oppositely when ferroelectrics is transformed to antiferroelectrics or paraelectrics the volume contracts. In the transition of antiferroelectric orthorhombic structure to tetragonal structure or ferroelectric low-temperature rhombohedral structure to high-tem- perature rhombohedral structure, there are also revealed apparent anomalies in the curves of thermal expansion. Among them, the volume strain caused by the transition between antiferroelectrics and ferroelectrics is the biggest in magnitude, and the linear expansion dL/L0 and the expansion coefficient (dL/L0)/dT can reach 2.810?3 and 7.5 × 10?4 K?1 respectively.

  16. Investigation of sintering kinetics of magnesium titanate

    Directory of Open Access Journals (Sweden)

    Petrović V.V.

    2013-01-01

    Full Text Available Obtaining new materials including sintered electronic materials using different procedures is the consequence of long complex and expensive experimental work. However, the dynamics of expansive development of electronic devices requires fast development of new materials, especially sintered oxide materials. The recent rapid development of electronics is among other things due to development and improvement of new components based on titanate ceramics. Research in this work has included an experimental study of the synthesis of dielectric ceramics in the system MgCO3 - TiO2. Starting powders were mechanically activated by milling in a high energy planetary mill for different times. Samples were prepared for isothermal sintering at 1100ºC by dual pressing of powders into cylindrical samples in a hydraulic press.

  17. Novel thermal expansion of lead titanate

    Institute of Scientific and Technical Information of China (English)

    XING Xianran; DENG Jinxia; CHEN Jun; LIU Guirong

    2003-01-01

    Lattice parameters of lead titanate were precisely re-determined in the ternperature range of-150-950℃ by high precision XRPD measurements. It was clarified that there was no any evidence for a new phase transition at low temperatures. Tetragonal distortion strain decreases with temperature increasing. A novel thermal expansion was observed, positive thermal expansion from-150℃ to room temperature (RT) and above 490℃, and the negative thermal expansion in the temperature range of RT-490℃. A big jump of thermal expansion coefficient is attributed to the tetragonal-cubic phase transition. A rationalization for the negative thermal expansion of PbTiO3 is due to the decrease of anion-anion repulsion as polyhedra become more regular at heating. The mechanisms of positive and negative thermal expansions were elucidated as the same nature in the homogenous tetragonal phase at present case.

  18. Extrusion and properties of lead zirconate titanate piezoelectric ceramics

    DEFF Research Database (Denmark)

    Cai, S.; Millar, C.E.; Pedersen, L.;

    1997-01-01

    The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

  19. The TITAN Reversed-Field Pinch fusion reactor study

    International Nuclear Information System (INIS)

    The TITAN Reversed-Field Pinch (RFP) fusion reactor study is a multi-institutional research effort to determine the technical feasibility and key developmental issues of an RFP fusion reactor, especially at high power density, and to determine the potential economics, operations, safety, and environmental features of high-mass-power-density fusion systems. The TITAN conceptual designs are DT burning, 1000 MWe power reactors based on the RFP confinement concept. The designs are compact, have a high neutron wall loading of 18 MW/m2 and a mass power density of 700 kWe/tonne. The inherent characteristics of the RFP confinement concept make fusion reactors with such a high mass power density possible. Two different detailed designs have emerged: the TITAN-I lithium-vanadium design, incorporating the integrated-blanket-coil concept; and the TITAN-II aqueous loop-in-pool design with ferritic steel structure. This report contains a collection of 16 papers on the results of the TITAN study which were presented at the International Symposium on Fusion Nuclear Technology. This collection describes the TITAN research effort, and specifically the TITAN-I and TITAN-II designs, summarizing the major results, the key technical issues, and the central conclusions and recommendations. Overall, the basic conclusions are that high-mass power-density fusion reactors appear to be technically feasible even with neutron wall loadings up to 20 MW/m2; that single-piece maintenance of the FPC is possible and advantageous; that the economics of the reactor is enhanced by its compactness; and the safety and environmental features need not to be sacrificed in high-power-density designs. The fact that two design approaches have emerged, and others may also be possible, in some sense indicates the robustness of the general findings

  20. The TITAN Reversed-Field Pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1988-03-01

    The TITAN Reversed-Field Pinch (RFP) fusion reactor study is a multi-institutional research effort to determine the technical feasibility and key developmental issues of an RFP fusion reactor, especially at high power density, and to determine the potential economics, operations, safety, and environmental features of high-mass-power-density fusion systems. The TITAN conceptual designs are DT burning, 1000 MWe power reactors based on the RFP confinement concept. The designs are compact, have a high neutron wall loading of 18 MW/m{sup 2} and a mass power density of 700 kWe/tonne. The inherent characteristics of the RFP confinement concept make fusion reactors with such a high mass power density possible. Two different detailed designs have emerged: the TITAN-I lithium-vanadium design, incorporating the integrated-blanket-coil concept; and the TITAN-II aqueous loop-in-pool design with ferritic steel structure. This report contains a collection of 16 papers on the results of the TITAN study which were presented at the International Symposium on Fusion Nuclear Technology. This collection describes the TITAN research effort, and specifically the TITAN-I and TITAN-II designs, summarizing the major results, the key technical issues, and the central conclusions and recommendations. Overall, the basic conclusions are that high-mass power-density fusion reactors appear to be technically feasible even with neutron wall loadings up to 20 MW/m{sup 2}; that single-piece maintenance of the FPC is possible and advantageous; that the economics of the reactor is enhanced by its compactness; and the safety and environmental features need not to be sacrificed in high-power-density designs. The fact that two design approaches have emerged, and others may also be possible, in some sense indicates the robustness of the general findings.

  1. Titan's missing ethane: From the atmosphere to the subsurface

    Science.gov (United States)

    Gilliam, Ashley E.; Lerman, Abraham

    2016-09-01

    The second most abundant component of the present-day Titan atmosphere, methane (CH4), is known to undergo photolytic conversion to ethane (C2H6) that accumulates as a liquid on Titan's surface. Condensation temperature of ethane is higher than that of methane, so that ethane "rain" may be expected to occur before the liquefaction of methane. At present, the partial pressure of ethane in the atmosphere is 1E-5 bar, much lower than 1E-1 bar of CH4. Estimated 8.46E17 kg or 1.37E6 km3 of C2H6 have been produced on Titan since accretion. The Titan surface reservoirs of ethane are lakes and craters, of estimated volume of 50,000 km3 and 61,000 km3, respectively. As these are smaller than the total volume of liquid ethane produced in the course of Titan's history, the excess may be stored in the subsurface of the crust, made primarily of water ice. The minimum porosity of the crust needed to accommodate all the liquid ethane would be only 0.9% of the uppermost 2 km of the crust. The occurrence of CH4 and liquid C2H6 on Titan has led to much speculation on the possibility of life on that satellite. The aggregation of organic molecules in a "primordial soup or bullion" depends in part on the viscosity of the medium, diffusivity of organic molecules in it, and rates of polymerization reactions. The temperatures on Titan, much lower than on primordial Earth, are less favorable to the "Second Coming of life" on Titan.

  2. Photoreactivity of condensed species on Titan's aerosols analogues

    Science.gov (United States)

    Fleury, Benjamin; Gudipati, Murthy; Carrasco, Nathalie

    2016-10-01

    Titan's aerosols formation is initiated in the upper atmospheric layers at about 1000 km by the dissociation and the ionization of N2 and CH4 by the VUV solar photons [1]. Then, they aggregate and sediment to the surface. The temperatures of the stratosphere and the troposphere [3] (measured by the HASI instrument onboard the Huygens probe [2]) allow the condensation of many volatile organics on the solid aerosols, forming organic ice coating on the aerosol polymers. We will present an experimental study simulating this process and discuss the photoreactivity of condensed species on Titan's aerosols analogues in the atmosphere and on the surface. We demonstrated experimentally that the organic aerosols, which cover the Titan's surface, drive the photoreactivity of condensed species such as acetylene when they are irradiated with long wavelength photons (λ > 300 nm). This result highlights that Titan's surface remains active despite the absorption of the most energetic photons by the atmosphere.AcknowledgmentsThis work is supported by NASA Solar System Workings grant " Photochemistry in Titan's Lower Atmosphere". The research work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. NC acknowledges the European Research Council for their financial support (ERC Starting Grant PRIMCHEM, grant agreement n°636829).References[1] Waite, J. H., et al., The process of Tholin formation in Titan's upper atmosphere, (2007), Science 316, 870-875.[2] Fulchignoni, M., et al., In situ measurements of the physical characteristics of Titan's environment, (2005), Nature 438, 785-791[3] Lavvas, P., et al., Condensation in Titan's atmosphere at the Huygens landing site, (2011), Icarus 215, 732-750.

  3. Modified strontium titanates: From defect chemistry to SOFC anodes

    DEFF Research Database (Denmark)

    Verbraeken, M.C.; Ramos, Tania; Agersted, Karsten;

    2015-01-01

    Modified strontium titanates have received much attention recently for their potential as anode material in solid oxide fuel cells (SOFC). Their inherent redox stability and superior tolerance to sulphur poisoning and coking as compared to Ni based cermet anodes could improve durability of SOFC...... systems dramatically. Various substitution strategies can be deployed to optimise materials properties in these strontium titanates, such as electronic conductivity, electrocatalytic activity, chemical stability and sinterability, and thus mechanical strength. Substitution strategies not only cover choice...

  4. Plasma environment of Titan: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

    Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

  5. Earth-Based Support for the Titan Saturn System Mission

    Science.gov (United States)

    Coustenis, Athena; Lunine, Jonathan; Lebreton, Jean-Pierre; Matson, Dennis; Erd, Christian; Reh, Kim; Beauchamp, Patricia; Lorenz, Ralph; Waite, Hunter; Sotin, Christophe; Gurvits, Leonid; Hirtzig, Mathieu

    2009-09-01

    The Titan Saturn System Mission (TSSM) concept is composed of a TSSM orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the probe/lake lander. One overarching goal of TSSM is to explore in situ the atmosphere and surface of Titan. The mission has been prioritized as the second Outer Planets Flagship Mission, the first one being the Europa Jupiter System Mission (EJSM). TSSM would launch around 2023-2025 arriving at Saturn 9 years later followed by a 4-year science mission in the Saturn system. Following delivery of the in situ elements to Titan, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys before entering into a dedicated orbit around Titan. The Titan montgolfière aerial vehicle under consideration will circumnavigate Titan at a latitude of ~20° and at altitudes of ~10 km for a minimum of 6 months. The probe/lake lander will descend through Titan’s atmosphere and land on the liquid surface of Kraken Mare (~75° north latitude). As for any planetary space science mission, and based on the Cassini-Huygens experience, Earth-based observations will be synergistic and enable scientific optimization of the return of such a mission. Some specific examples of how this can be achieved (through VLBI and Doppler tracking, continuous monitoring of atmospheric and surface features, and Direct-to-Earth transmission) are described in this paper.

  6. Piezoelectric bismuth titanate ceramics for high temperature applications

    OpenAIRE

    Shulman, Holly Sue; Setter, Nava

    2005-01-01

    Bismuth titanate (Bi4Ti3O12) shows promise in piezoelectric applications in a temperature range (300-600 °C) which is not well served by standard piezoelectric ceramics. The proposal to use bismuth titanate ceramics for these applications has a major flaw, namely that the high electrical conductivity precludes the efficient polarization of these materials in an electric field. The degree of polarization is critical since it is directly related to the piezoelectric response. In addition, once ...

  7. Plasma-ion Induced Sputtering and Heating of Titan's Atmosphere

    Science.gov (United States)

    Johnson, R. E.; Tucker, O. J.

    2007-05-01

    Titan is unique among the outer solar system icy satellites in having an atmosphere with a column density about ten times that of the Earth's atmosphere and an atmospheric mass to solid mass ratio comparable to that of Venus. Atmospheres equivalent in size to that at Titan would have been removed from the icy Galilean satellites by the plasma trapped in the Jovian magnetosphere (Johnson 2004). Therefore, the use of Cassini data to determine the present erosion rate of Titan's atmosphere provides an important end point for studying the erosion and heating of planetary and satellite atmospheres by an ambient plasma. In this paper we describe the deposition of energy, the erosion and the expansion of the upper atmosphere of Titan using Direct Simulation Monte Carlo models (Shematovich et al. 2003; Michael et al. 2005; Michael and Johnson 2005). These calculations are used to calibrate semi-empirical models of atmospheric sputtering (Johnson 1994) that are used to interpret Cassini data at Titan. Using a number of plasma conditions, the temperature and density vs. altitude above the exobase and the rate of escape are calculated. References: Johnson, R.E. "Plasma-induced Sputtering of an Atmosphere" in Space Science Reviews 69 215-253 (1994). Johnson. R.E., " The magnetospheric plasmadriven evolution of satellite atmospheres" Astrophys. J. 609, L99-L102 (2004). Michael, M. and R.E. Johnson, "Energy deposition of pickup ions and heating of Titan's atmosphere", Planetary & Space Sci.53, 1510-1514 (2005). Michael M., R.E. Johnson, F. Leblanc, M. Liu, J.G. Luhmann, and V.I. Shematovich, "Ejection of nitrogen from Titan's atmosphere by magnetospheric ions and pick-up ions", Icarus 175, 263-267 (2005). Shematovich, V.I., R.E. Johnson, M. Michael, and J.G. Luhmann, "Nitrogen loss from Titan", JGR 108, No. E8, 5087, doi:10.1029/2003JE002094 (2003).

  8. Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

    Science.gov (United States)

    Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

    2016-10-01

    Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

  9. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    Science.gov (United States)

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. PMID:26794953

  10. Preparation and properties of yttria doped tetragonal zirconia polycrystal/Sr-doped barium hexaferrite ceramic composites

    International Nuclear Information System (INIS)

    Highlights: • The 3Y-TZP/Sr-doped barium ferrite composites were prepared. • The saturation magnetization was improved by 15% with Sr-doping. • The dispersion coefficient p could reflect the microscopic lattice variation. • The composite with x = 0.5 had the maximum fracture toughness of 8.3 MPa m1/2. - Abstract: The effects of substitution of Ba2+ by Sr2+ on the magnetic property of barium ferrite and addition barium ferrite secondary phase to the 3 mol% yttria-doped tetragonal zirconia polycrystal (3Y-TZP) matrix on the mechanical property of composites were investigated. The Sr-doped barium ferrite (Ba1−xSrxFe12O19, x = 0, 0.25, 0.50 and 0.75) was synthesized by solid-state reaction in advance. Then 3Y-TZP/20 wt% Sr-doped barium ferrite composites were prepared by means of conventional ceramic method. It was found that a moderate amount of Sr added to barium ferrite could boost the saturation magnetization by 15% compared with the composites without Sr-doping. Besides, the composite with x = 0.50 possessed the best mechanical properties, such as 11.5 GPa for Vickers hardness and 8.3 MPa m1/2 for fracture toughness, respectively. It was demonstrated that magnetic and mechanical properties of the composites could be harmonized by the incorporation of barium ferrite secondary phase

  11. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    Science.gov (United States)

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.

  12. Carbon dioxide chemistry on the surface of Titan

    Science.gov (United States)

    Hodyss, Robert; Piao, Sophie; Malaska, Michael; Cable, Morgan

    2016-10-01

    Titan possesses many of the basic elements of habitability, including a rich organic chemistry. However, the thick atmosphere of Titan shields the surface from radiation, which makes the incorporation of oxygen into organic compounds difficult, due to a reducing environment and low temperatures that slow chemical reactions. These obstacles may be overcome by impacts or cryovolcanic heating of ice, which would mix organics with liquid water and allow chemical reactions that can incorporate oxygen. However, reactions involving oxygen can occur on Titan without invoking such unusual conditions. We show that the reaction of carbon dioxide with amines can lead to oxygenated organics at Titan's surface without the need for external energy input, via the carbamation reaction: R-NH2 + CO2 → R-NH-COOH. Using a combination of micro-Raman spectroscopy and UHV FTIR spectroscopy, we examine the reaction products and kinetics of the carbamation reaction for a variety of primary and secondary amines. We have observed carbamic acid formation in mixtures of methylamine, ethylamine and dibutylamine with CO2 at cryogenic temperatures. This indicates that both primary and secondary amines can undergo carbamation at low temperatures. Reaction was observed with methylamine as low as 40 K, and with ethylamine at 100 K, demonstrating that carbamation is fast at Titan surface temperatures. We will present data on the kinetics of the carbamation reaction for a variety of amines, as well as estimates of the quantity of carbamic acids that may be produced on Titan's surface and in the atmosphere.

  13. Titan atmospheric composition by hypervelocity shock layer analysis

    Science.gov (United States)

    Nelson, H. F.; Park, Chul; Whiting, Ellis E.

    1989-01-01

    The Cassini Mission, a NASA/ESA cooperative project which includes a deployment of probe into the atmosphere of Titan, is described, with particular attention given to the shock radiometer experiment planned for the Titan probe for the analysis of Titan's atmosphere. Results from a shock layer analysis are presented, demonstrating that the mole fractions of the major species (N2, CH4, and, possibly Ar) in the Titan atmosphere can be successfully determined by the Titan-probe radiometer, by measuring the intensity of the CN(violet) radiation emitted in the shock layer during the high velocity portion of the probe entry between 200 and 400 km altitude. It is shown that the sensitivity of the CN(violet) radiation makes it possible to determine the mole fractions of N2, CH4, and Ar to about 0.015, 0.003, and 0.01, respectively, i.e., much better than the present uncertainties in the composition of Titan atmosphere.

  14. Chemistry of neutral species in Titan's ionosphere: an experimental approach

    Science.gov (United States)

    Dubois, David

    2016-06-01

    Titan's gas phase atmospheric chemistry leading to the formation of solid organic aerosols can be simulated in laboratory simulations. Typically, plasma reactors can be used to achieve Titan-like conditions. The discharge induces photodissociation and photoionization processes to the N2 -CH4 mixture. It faithfully reproduces the electron energy range of magnetospheric electrons entering Titan's atmosphere and it can also approximate the solar UV input at Titan's ionosphere. In this context, it is deemed necessary to apply and exploit such a technique in order to better understand the chemical reactivity occurring in Titan-like conditions. In the present work, we use the Pampre cold dusty plasma experiment with an N2 -CH4 gaseous mixture under controlled pressure and gas influx, hence, emphasizing on the gas phase which we know is key to the formation of aerosols on Titan. An internal cryogenic trap has been developed to accumulate the gas products during their production and facilitate their detection. Those are identified and quantified by in situ mass spectrometry and infrared spectroscopy. We present here results from this experiment in an 90-10% N2 -CH4 mixing ratio, using a quantitative approach on nitriles and polycyclic aromatic hydrocarbons.

  15. Direct hydrothermal synthesis and magnetic property of titanate nanotubes doped magnetic metal ions

    Institute of Scientific and Technical Information of China (English)

    Meili Wang; Gongbao Song; Jian Li; Landong Miao; Baoshu Zhang

    2008-01-01

    Pure titanate nanotubes and titanate nanotubes doped with Fe3+/Ni2+/Mn2+ ions were synthesized by the hydrothermal method. In this process, titanate nanotubes were first prepared synchronously with doping Fe3+/Ni2+/Mn2+ ions. The morphology,structure, thermal stability and magnetic property of titanate nanotubes were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and magnetic measurement. The titanate nanotubes transformed into the anatase titania nanocrystals,and further the mixture of anatase and rutile titania along with increasing temperature. The results indicate that the titanate nanotubes doped with Fe3+/Ni2+/Mn2+ ions are paramagnetic behaviors.

  16. Wideband and enhanced microwave absorption performance of doped barium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Pingyuan; Xiong, Kun [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Ju, Kui [Guizhou Institute of Metallurgy and Chemical Engineering, Guiyang 550002 (China); Li, Shengnan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2015-07-01

    To achieve stronger microwave attenuation and larger bandwidth in electromagnetic absorber, the nickel ions (Ni{sup 2+}) and manganese ions (Mn{sup 2+}) were employed to partially replace the cobalt ions (Co{sup 2+}) in BaCoTiFe{sub 10}O{sub 19}, and the doped barium hexaferrite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19}) powders were synthesized via the sol–gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the ferrite powders with the paraffin. The X-ray diffraction (XRD) patterns of the doped ferrites confirmed the formation of the M-type barium ferrite, and no other types of barium ferrite could be found. Based on the electromagnetic parameters measured by the vector net-analyzer, it was found that the composite (Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19}) possessed a minimum reflection loss of −52.8 dB at 13.4 GHz with a matching thickness of 1.8 mm and the bandwidth below −15 dB was 5.8 GHz. Moreover, the maximum attenuation of Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could reach −69 dB when its thickness was 1.8 mm, and also the bandwidth less than −20 dB was ranging from 13.2 GHz to 18 GHz. Thus, Ba(MnNi){sub 0.2}Co{sub 0.6}TiFe{sub 10}O{sub 19} and Ba(MnNi){sub 0.25}Co{sub 0.5}TiFe{sub 10}O{sub 19} could be the good microwave absorbers, which have great potentials to be applied in the high frequency fields of the microwave absorbing materials. - Highlights: • The Co was first time substituted by Mn–Ni in ferrites. • The substituted ferrites had good microwave absorption. • The doped ferrites had broad bandwidth and low reflection loss.

  17. A Comparative Study on Magnetostructural Properties of Barium Hexaferrite Powders Prepared by Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Zehra Durmus

    2014-01-01

    Full Text Available Nanocrystalline particles of barium hexaferrite were synthesized by a sol-gel combustion route using nitrate-citrate gels prepared from metal nitrates and citric acid solutions with Fe/Ba molar ratio 12. The present paper aims to study the effect of addition of polyethylene glycol (PEG solutions with different molecular weights (MW: 400, 2000, and 10.000 g/mol on magnetostructural properties of barium hexaferrite. The formation of the barium hexaferrite was inspected using X-ray diffraction (XRD analysis, Fourier transform infrared (FT-IR analysis, thermogravimetric (TGA analysis, scanning electron microscopy (SEM analysis and vibrating sample magnetometer (VSM analysis for magnetic measurements.

  18. Microscopic insight into nuclear structure properties of proton-rich barium isotopes

    International Nuclear Information System (INIS)

    Variation after projection (VAP) calculations with Hartree-Bogoliubov (HB) Ansatz have been carried out for A=120-136 barium isotopes. In this framework, the yrast spectra with Jmaxπ=10+, B(E2) transition probabilities, quadrupole (β2) and hexadecapole (β4) deformation parameters for even-even barium isotopes have been obtained. The results of the calculation give an indication that it is important to include the hexadecapole-hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in these barium isotopes. (author)

  19. Application of barium fluoride for sulfur selective extraction at X-ray spectroscopic analysis of steel

    International Nuclear Information System (INIS)

    In order to increase the sensitivity of X-ray spectroscopic identification of sulphur in steels the application of barium fluoride for selective extraction of sulphate ions was proposed by authors of present work. The influence of concentration of sulphate ions, iron, nickel, chromium and titanium cations as well as acidity of solutions on the coefficient of distribution of sulphate ions in the system barium fluoride-water was studied. The distribution coefficients were calculated, the completeness of extraction was calculated as well. It is defined that sulphate ions from solutions containing cations of heavy metals and other anions can be extracted by means of barium fluoride.

  20. Barium ferrite nanoparticles prepared by self-propagating low-temperature combustion method and its characterization

    Indian Academy of Sciences (India)

    P M Prithviraj Swamy; S Basavaraja; Vijayanand Havanoor; N V Srinivas Rao; R Nijagunappa; A Venkataraman

    2011-12-01

    The barium ferrite particles were prepared using a self-propagating low-temperature combustion method using polyethylene glycol (PEG) as a fuel. The process was investigated with simultaneous thermogravimetric-differential thermal analysis (TG–DTA). The crystalline structure, morphology and the magnetic properties of the barium ferrite particles were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and SQUID susceptometer. The results show that the ignition temperature of PEG is lower compared with other combustion methods and gives nanocrystalline barium ferrite.