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Sample records for barium titanate ceramics

  1. 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.

  2. Experimental studies on 3D printing of barium titanate ceramics for medical applications

    Directory of Open Access Journals (Sweden)

    Schult Mark

    2016-09-01

    Full Text Available The present work deals with the 3D printing of porous barium titanate ceramics. Barium titanate is a biocompatible material with piezoelectric properties. Due to insufficient flowability of the starting material for 3D printing, the barium titanate raw material has been modified in three different ways. Firstly, barium titanate powder has been calcined. Secondly, flow additives have been added to the powder. And thirdly, flow additives have been added to the calcined powder. Finally, a polymer has been added to the three materials and specimens have been printed from these three material mixtures. The 3D printed parts were then sintered at 1320°C. The sintering leads to shrinkage which differs between 29.51–71.53% for the tested material mixtures. The porosity of the parts is beneficial for cell growth which is relevant for future medical applications. The results reported in this study demonstrate the possibility to fabricate porous piezoelectric barium titanate parts with a 3D printer that can be used for medical applications. 3D printed porous barium titanate ceramics can especially be used as scaffold for bone tissue engineering, where the bone formation can be promoted by electrical stimulation.

  3. Synthesis and characterization of nickel oxide doped barium strontium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, M. [Dept. of Electrical Engineering, Bengal Institute of Technology Kolkata (India); Mukherjee, S. [Dept. of Metallurgical Engineering, Jadavpur University, Kolkata (India); Maitra, S. [Govt. College of Engg. and Ceramic Technology, Kolkata (India)

    2012-01-15

    Barium strontium titanate (BST) ceramics (Ba{sub 0.6}Sr{sub 0.4})TiO{sub 3} were synthesized by solid state sintering using barium carbonate, strontium carbonate and rutile as the precursor materials. The samples were doped with nickel oxide in different proportions. Different phases present in the sintered samples were determined from X-ray diffraction investigation and the distribution of different phases in the microstructure was assessed from scanning electron microscopy study. It was observed that the dielectric properties of BST were modified significantly with nickel oxide doping. These ceramics held promise for applications in tuned circuits. (author)

  4. Review - Fabrication of crystal-oriented barium-bismuth titanate ceramics in high magnetic field and subsequent reaction sintering

    Directory of Open Access Journals (Sweden)

    Satoshi Tanaka, Yusuke Tomita, Ryoichi Furushima, Hiroyuki Shimizu, Yutaka Doshida and Keizo Uematsu

    2009-01-01

    Full Text Available High magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 ° C.

  5. Microstructural and Electrical Characterization of Barium Strontium Titanate-Based Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition

    Science.gov (United States)

    2003-04-03

    Strontium Titanate-Based Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition DISTRIBUTION: Approved for public...Society H2.4 Microstructural and Electrical Characterization of Barium Strontium Titanate- based Solid Solution Thin Films Deposited on Ceramic...investigated and report the microstructural and electrical characterization of selected barium strontium titanate-based solid solution thin films

  6. 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.

  7. Preparation and Sintering Effect in Quartz-Barium Titanate Porous Ceramics and Permeability Modulation Using an Implanted Electrode

    Directory of Open Access Journals (Sweden)

    Ernesto Suaste Gómez

    2014-01-01

    Full Text Available Barium titanate and quartz mixed in different proportions were used to create porous piezoelectric ceramics. Three different sintering temperatures were used for the ceramics preparation; a nichrome wire was used as internal electrode in porous ceramics. Characteristics as porous area, porosity, and its relationship with quartz percentage and sintering temperatures were studied. Porous ceramics with an implanted electrode were created, by applying an alternating voltage in the internal electrode that controlled the liquid permeability coefficient, calculated by the Darcy Law.

  8. Contribution of the irreversible displacement of domain walls to the piezoelectric effect in barium titanate and lead zirconate titanate ceramics

    CERN Document Server

    Damjanovic, D

    1997-01-01

    The contribution from the irreversible displacement of non-180 deg domain walls to the direct longitudinal piezoelectric d sub 3 sub 3 coefficient of BaTiO sub 3 and Pb(Zr, Ti)O sub 3 ceramics was determined quantitatively by using the Rayleigh law. Effects of the crystal structure and microstructure of the ceramics as well as the external d.c. pressure on the domain wall contribution to d sub 3 sub 3 were examined. In barium titanate, this domain wall contribution is large (up to 35% of the total d sub 3 sub 3 , under the experimental conditions used) and dependent on the external d.c. pressure in coarse grained ceramics, and much smaller and independent of the external d.c. pressure in fine-grained samples. The presence of internal stresses in fine-grained ceramics could account for the observed behaviour. The analysis shows that the domain-wall contribution to the d sub 3 sub 3 in lead zirconate titanate ceramics is large in compositions close to the morphotropic phase boundary that contain a mixture of te...

  9. Dielectric properties of barium strontium titanate / non ferroelectric oxide ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Nenez, S. [THALES, Domaine de Corbeville, Orsay (France); Univ. de Bourgogne, Lab. de Recherche sur la Reactivite des Solides, Dijon (France); Morell, A.; Pate, M.; Ganne, J.P. [THALES, Domaine de Corbeville, Orsay (France); Maglione, M. [Inst. de Chimie de la Matiere Condensee de Bordeaux - CNRS, Pessac (France); Niepce, J.C. [Univ. de Bourgogne, Lab. de Recherche sur la Reactivite des Solides, Dijon (France)

    2002-07-01

    Barium strontium titanate ceramics present high dielectric permittivity and tunability. In order to reduce their permittivity and loss tangent while keeping tunability, various composites of barium strontium titanate oxide Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} combined with non-ferroelectric oxides such as magnesium titanate MgTiO{sub 3} or magnesia MgO were investigated. The Ba-Sr oxide powder was mixed with 20, 40 or 60 wt% of the non-ferroelectric oxide (NFO). The paper discusses the processing and the material characterisations by X-ray diffraction and SEM. A secondary phase BaMg{sub 6}Ti{sub 6}O{sub 19} was detected only in the composites synthesised with MgTiO{sub 3}. The microstructure and the dielectric characteristics are presented and discussed. A correlation between the microstructure of the composites, including secondary phase and the dielectric properties is proposed. (orig.)

  10. Investigation of ferroelectric properties on nanocrystalline barium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Xiangyun; WANG Xiaohui; LI Dejun; LI Longtu

    2007-01-01

    Dense nanocrystalline BaTiO3(BT) ceramics with 50 nm average grain size obtained by spark plasma sintering were investigated.The dielectric data showed a ferropara phase transition with a maximum permittivity of 1,602 at 1 20℃ and at 1 kHZ.The polarization reversal characteristics were measured,and the typical piezoelectric hysteresis loop was recorded.The asymmetry of permanent polarization and coercive field in polarization-electric field curves were obtained and attributed to the existence of an internal electric field.The present results provide experimental evidence,indicating that if a critical grain size exists for ferroelectricity,then it is less than 50 nm for polycrystalline BT ceramics.

  11. 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.

  12. 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.

  13. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-03-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} ( y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  14. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-01-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} (y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  15. History and challenges of barium titanate: Part I

    Directory of Open Access Journals (Sweden)

    Vijatović M.M.

    2008-01-01

    Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application. The used method has a significant influence on the structure and properties of barium titanate materials. In this review paper, Part I contains a study of the BaTiO3 structure and frequently used synthesis methods.

  16. 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.

  17. Processing science of barium titanate

    Science.gov (United States)

    Aygun, Seymen Murat

    barium titanate phase formation. The exhaust gases emitted during the firing of barium titanate films were monitored using a residual gas analyzer (RGA) to investigate the effects of ramp rate and oxygen partial pressure. The dielectric properties including capacitor yield were correlated to the RGA data and microstructure. This information was used to tailor a thermal profile to obtain the optimum dielectric response. A ramp rate of 20°C/min and a pO2 of 10-13 atm resulted in a permittivity of 1500, a loss tangent of 0.035 and a 90% capacitor yield in 0.5 mm dot capacitors. Yield values above 90% represent a significant advantage over preexisting reports and can be attributed to an improved ability to control final porosity. Finally, the dramatic enhancement in film density was demonstrated by understanding the processing science relationships between organic removal, crystallization, and densification in chemical solution deposition. The in situ gas analysis was used to develop an each-layer-fired approach that provides for effective organic removal, thus pore elimination, larger grain sizes, and superior densification. The combination of large grain size and high density enabled reproducing bulk-like dielectric properties in a thin film. A room temperature permittivity of 3000, a 5 muF/cm2 capacitance density, and a dielectric tunability of 15:1 were achieved. By combining the data sets generated in this thesis with those of comparable literature reports, we were able to broadly rationalize scaling effects in polycrystalline thin films. We show that the same models successfully applied to bulk ceramic systems are appropriate for thin films, and that models involving parasitic interfacial layers are not needed. Developing better models for scaling effects were made possible solely by advancing our ability to synthesize materials thus eliminating artifacts and extrinsic effects.

  18. Luminescence properties of barium--gadolinium-titanate ceramics doped with rare-earth ions (Eu3+ and Tb3+).

    Science.gov (United States)

    Hemasundara Raju, S; Muni Sudhakar, B; Sudhakar Reddy, B; Dhoble, S J; Thyagarajan, K; Nageswara Raju, C

    2014-11-01

    Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 →(7)F2) with an excitation wavelength λ(exci)  = 408 nm ((7)F0 → (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 → (7)F5) with an excitation wavelength λ(exci)  = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.

  19. Chemical bonding and charge density distribution analysis of undoped and lanthanum doped barium titanate ceramics

    Indian Academy of Sciences (India)

    J MANGAIYARKKARASI; R SARAVANAN; MUKHLIS M ISMAIL

    2016-12-01

    A-site deficient, Lanthanum substituted Ba1−xLa2x/3TiO3 (x=0.000, 0.005, 0.015, 0.020 and 0.025) ceramics have been synthesized by chemical route. The effects of lanthanum dopant on the BaTiO3 lattice and the electron density distributions in the unit cell of the samples were investigated. Structural studies suggested the reduction in cell parameters and shrinkage in cell volume with the increase in lanthanum content. Chemical bonding and electron density distributions were examined through high resolution maximum entropy method (MEM). The mid bond electron density values revealed the enhancement of covalent nature between titanium and oxygen ions and predominant ionic nature between barium and oxygen ions. Average grain sizes were estimated for the undoped and doped samples. SEM investigations showed the existence of smaller grains with large voids in between them.

  20. 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.)

  1. Temperature dependence dielectric properties of modified barium titanate-PVB composites

    Science.gov (United States)

    Joshi, N. J.; Rakshit, P. B.; Grewal, G. S.; Shrinet, V.; Pratap, A.

    2013-06-01

    In this work, attempts are made to prepare ceramic polymer-composite followed by characterization of dielectric properties. The Barium Titanate ceramic powders are synthesized using the hydrothermal process. Silane treatment is carried out on Barium Titanate powder to increase its compatibility with polymer, followed with preparation of ceramic-polymer composite. Polyvinyl Butyral (PVB) is used as matrix for preparation of the composites and the concentration of Barium Titanate is increased from 60 to 90 wt%. Dielectric properties such as volume resistivity, dielectric constant, dissipation factor are evaluated. Results indicate that the dielectric constant and dissipation factor vary between 52 to 120 and 0.01 to 0.07; respectively as the relative ratio of polymer and silane modified Barium Titanate is varied. Specifically, at 90 wt% of silane modified Barium Titanate, the highest dielectric constant of 123 along with dissipation factor of 0.07 is obtained.

  2. Semiconducting barium titanate ceramics prepared by using yttrium hexaboride as sintering aid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.X.; Chan, H.L.W.; Pang, G.K.H.; Choy, C.L

    2003-07-25

    Nb-doped BaTiO{sub 3} semiconducting ceramics have been prepared at 1150 deg. C by employing YB{sub 6} as the sintering aid. The low-temperature sintered samples exhibit a positive temperature coefficient of resistivity (PTCR) effect. The room-temperature resistivity and the magnitude of PTCR effect depend on the amount of YB{sub 6} added, the Nb{sub 2}O{sub 5} content and the sintering conditions. At 1 mol% of YB{sub 6}, the sample has a low room-temperature resistivity and a resistivity jump of about 10{sup 4}. Transmission electron microscope studies revealed that the intergranular region between the crystalline BaTiO{sub 3} grains has an amorphous structure. Y, Ba and Ti are present in the intergranular region but no Y is detectable in the crystalline grains. A liquid phase is believed to be present during sintering and it helps to facilitate the densification process and to enhance the PTCR effect.

  3. 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.

  4. The influence of small stoichiometric deviations in the properties dielectric of barium titanate ceramics laser sintering; A influencia de pequenos desvios estequiometricos nas propriedades eletricas de ceramicas de titanato de bario sinterizadas a laser

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcelo Souza da; Silva, Ronaldo Santos da, E-mail: ssiilva990@hotmmail.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SP (Brazil). Departameneto de Fisica. Grupo de Materiais Ceramicos Avancados

    2012-07-01

    It has recently been investigated the influence of the laser sintering on the electrical properties of the ceramic bodies. This work is dedicated to studying how a small deviation stoichiometric barium and / or titanium may interfere with the dielectric properties of ceramics based on barium titanate (BaTiO3) when they are sintered by laser. Ceramics based on doped barium titanate lanthanum (Ba{sub 0,998}La{sub 0,002}Ti{sub 1-n}O{sub 3}) were produced and laser sintering. The crystalline phase was verified by X-ray diffraction, information on the microstructure of the sintered samples laser were obtained with the aid of the technique of electron microscopy (SEM) and, the impedance spectroscopy technique was used to characterize the dielectric material. The preliminary results obtained show ceramic bodies with a density of 93% and with good homogeneity of the microstructure. The high values of dielectric permittivity of the ceramics were observed for samples with a deviation where the stoichiometric ratio [Ba]/[Ti] <1. (author)

  5. 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)

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    SHI Qizhen; CUI Bin; WANG Hui; TIAN Jing; CHANG Zhuguo; HOU Yudong

    2005-01-01

    The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase.The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.

  13. 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.

  14. 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

  15. Liquid-Phase Processing of Barium Titanate Thin Films

    Science.gov (United States)

    Harris, David Thomas

    Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Review on dielectric properties of rare earth doped barium titanate

    Science.gov (United States)

    Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

    2016-07-01

    Rare earth doped Barium Titanate (BaTiO3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO3 downshifted the Curie temperature (TC). Transition temperature also known as Curie temperature, TC where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO3, Er-doped BaTiO3, Sm-doped BaTiO3, Nd-doped BaTiO3 and Ce-doped BaTiO3 had been proved to increase and the transition temperature or also known as TC also lowered down to room temperature as for all the RE doped BaTiO3 except for Er-doped BaTiO3.

  3. Heavy ion recoil spectrometry of barium strontium titanate films

    Science.gov (United States)

    Stannard, W. B.; Johnston, P. N.; Walker, S. R.; Bubb, I. F.; Scott, J. F.; Cohen, D. D.; Dytlewski, N.; Martin, J. W.

    1995-05-01

    Thin films of barium strontium titanate have been analysed using heavy ion recoil spectrometry with 77 and 98 MeV 127I ions at the new heavy ion recoil facility at ANSTO, Lucas Heights. New calibration procedures have been developed for quantitative analysis. Energy spectra for each of the elements present reveal interdiffusion that was not previously known.

  4. Magnetoelastic coupling in epitaxial cobalt ferrite/barium titanate heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gräfe, Joachim; Welke, Martin [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany); Bern, Francis; Ziese, Michael [Institut für Experimentelle Physik II, Universität Leipzig, Linnéstraße 5, 04103 Leipzig (Germany); Denecke, Reinhard, E-mail: denecke@uni-leipzig.de [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany)

    2013-08-15

    Ultra-thin cobalt ferrite films have been synthesised on ferroelectric barium titanate crystals. The cobalt ferrite films exhibit a magnetic response to strain induced by structural changes in the barium titanate substrate, suggesting a pathway to multiferroic coupling. These structural changes are achieved by heating through the phase transition temperatures of barium titanate. In addition the ferromagnetic signal of the substrate itself is taken into account, addressing the influence of impurities or defects in the substrate. The cobalt ferrite/barium titanate heterostructure is a suitable oxidic platform for future magnetoelectric applications with an established ferroelectric substrate and widely tuneable magnetic properties by changing the transition metal in the ferrite film. - Highlights: ► Ultra-thin CoFe{sub 2}O{sub 4} films grown on ferroelectric BaTiO{sub 3} crystals by PLD. ► Magnetic response to structural changes of BaTiO{sub 3} at transition temperatures. ► Significant magneto-elastic coupling of in-plane magnetisation in SQUID experiments. ► Clear distinction between contribution by BaTiO{sub 3} substrate and by CoFe{sub 2}O{sub 4} film.

  5. 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.

  6. 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.

  7. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, A.Z., E-mail: alezipo@yahoo.co [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Universidade Estadual Paulista- Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410 Guaratingueta, SP (Brazil); Moura, F.; Onofre, T.B. [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Ramirez, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-22

    Research highlights: {yields} Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) {yields} This is a genuine technique to obtain nanoparticles at low temperature and short times {yields} Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 {sup o}C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}) nanoparticles (BST) in the temperature range of 100-130 {sup o}C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO{sub 3} 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.

  8. Deflocculants for Tape Casting Barium Titanate Dielectrics.

    Science.gov (United States)

    1988-02-01

    bentone (13,14) pe trol n resina (13) Imthyl ablotate (13.23...Ceram Soc., May 1986, Chicago, Ill. 10. F. M. Fowkes, "Donor-Acceptor Interactions at Interfaces," J. Adhesion , ! 155-59 (1972). 11. G.N. Howatt

  9. Crystalline Structure, Defect Chemistry and Room Temperature Colossal Permittivity of Nd-doped Barium Titanate.

    Science.gov (United States)

    Sun, Qiaomei; Gu, Qilin; Zhu, Kongjun; Jin, Rongying; Liu, Jinsong; Wang, Jing; Qiu, Jinhao

    2017-02-13

    Dielectric materials with high permittivity are strongly demanded for various technological applications. While polarization inherently exists in ferroelectric barium titanate (BaTiO3), its high permittivity can only be achieved by chemical and/or structural modification. Here, we report the room-temperature colossal permittivity (~760,000) obtained in xNd: BaTiO3 (x = 0.5 mol%) ceramics derived from the counterpart nanoparticles followed by conventional pressureless sintering process. Through the systematic analysis of chemical composition, crystalline structure and defect chemistry, the substitution mechanism involving the occupation of Nd(3+) in Ba(2+) -site associated with the generation of Ba vacancies and oxygen vacancies for charge compensation has been firstly demonstrated. The present study serves as a precedent and fundamental step toward further improvement of the permittivity of BaTiO3-based ceramics.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Verification of the flexoelectricity in barium strontium titanate through d33 meter

    Directory of Open Access Journals (Sweden)

    Longlong Shu

    2016-12-01

    Full Text Available Flexoelectricity is a newly arising electromechanical property that couples strain gradient to polarization. This physical property widely exists in most of the solid dielectrics but has quite weak response that often overlooked. Recently, barium strontium titanate (BST, a well-known ferroelectrics, has been reported to be a promising flexoelectric material, and thus triggered the associated studies on flexoelectricity to a new height. However, part of the researchers argued the observed flexoelectricity in BST is either by residual piezoelectricity or centric symmetry breaking during the densification process. In this paper, we would verify the flexoelectricity in BST ceramics by many comparison experiments. Our experimental result suggested the observed polarization in BST material is likely to be induced by strain gradient through flexoelectricity.

  16. 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.

  17. 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.

  18. Crystallization behavior of a barium titanate tellurite glass doped with Eu3+ and Er3+

    Science.gov (United States)

    Ferreira, Elivelton Alves; Cassanjes, Fábia Castro; Poirier, Gael

    2013-04-01

    The main objective of this work has been to investigate the crystallization behavior of the glass composition 70TeO2-15BaO-15TiO2 doped with Eu3+ and Er3+ in order to check the possibility of obtaining transparent glass-ceramics containing rare earth-doped BaTiO3 nanocrystals. Glass samples with the ternary composition 70TeO2-15BaO-15TiO2 were synthesized by the melt-quenching method and doped with 0.1% of Eu3+ and Er3+. Thermal properties were investigated by DTA and heat-treatments were applied between Tg and Tx to induce the controlled crystallization of these glasses. One-step and two-step heat treatments were tested and the final glass-ceramics characterized by X-ray diffraction and UV-Vis absorption. It has been shown that transparent glass-ceramics can be obtained after heat-treatment but barium titanate BaTiO3 is hardly precipitated without coprecipitation of another crystalline phase identified as an isostructure of lanthanum tellurate. In addition, the crystalline volume fraction is relatively small in these transparent samples. Finally, Gold doping has been shown to be very effective to promote a volume nucleation and preferential crystallization of BaTiO3 over the other crystalline phases.

  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. 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.

  1. Synthesis and characterization of nickel oxide doped barium strontium titanate ceramics Síntese e caracterização de cerâmicas de titanato de estrôncio e bário dopado com óxido de níquel

    Directory of Open Access Journals (Sweden)

    M. Banerjee

    2012-03-01

    Full Text Available Barium strontium titanate (BST ceramics (Ba0.6Sr0.4TiO3 were synthesized by solid state sintering using barium carbonate, strontium carbonate and rutile as the precursor materials. The samples were doped with nickel oxide in different proportions. Different phases present in the sintered samples were determined from X-ray diffraction investigation and the distribution of different phases in the microstructure was assessed from scanning electron microscopy study. It was observed that the dielectric properties of BST were modified significantly with nickel oxide doping. These ceramics held promise for applications in tuned circuits.Cerâmicas de titanato de bário e estrôncio (TBS (Ba0,6Sr0,4TiO3 foram sintetizadas por sinterização do estado sólido usando carbonato de bário, carbonato de estrôncio e rutilo como materiais precursores. As amostras foram dopadas com diferentes proporções de óxido de níquel. Diferentes fases presentes nas amostras sinterizadas foram determinadas por difração de raios X e a distribuição de diferentes fases na microestrutura foi avaliada por microscopia eletrônica de varredura. Foi observado que as propriedades dielétricas do TBS foram modificadas significativamente com a dopagem do óxido de níquel. Essas cerâmicas são promissoras para aplicação em dispositivos.

  2. 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.

  3. Evaluation of antibacterial properties of Barium Zirconate Titanate (BZT nanoparticle

    Directory of Open Access Journals (Sweden)

    Simin Mohseni

    2014-12-01

    Full Text Available So far, the antibacterial activity of some organic and inorganic compounds has been studied. Barium zirconate titanate [Ba(Zr xTi1-xO3] (x = 0.05 nanoparticle is an example of inorganic materials. In vitro studies have provided evidence for the antibacterial activity of this nanoparticle. In the current study, the nano-powder was synthesized by sol-gel method. X-ray diffraction showed that the powder was single-phase and had a perovskite structure at the calcination temperature of 1000 ºC. Antibacterial activity of the desired nanoparticle was assessed on two gram-positive (Staphylococcus aureus PTCC1431 and Micrococcus luteus PTCC1625 and two gram-negative (Escherichia coli HP101BA 7601c and clinically isolated Klebsiella pneumoniae bacteria according to Radial Diffusion Assay (RDA. The results showed that the antibacterial activity of BZT nano-powder on both gram-positive and gram-negative bacteria was acceptable. The minimum inhibitory concentration of this nano-powder was determined. The results showed that MIC values for E. coli, K. pneumoniae, M. luteus and S. aureus were about 2.3 µg/mL, 7.3 µg/mL, 3 µg/mL and 12 µg/mL, respectively. Minimum bactericidal concentration (MBC was also evaluated and showed that the growth of E. coli, K. pneumoniae, M. luteus and S. aureus could be decreased at 2.3, 14, 3 and 18 µg/mL of BZT. Average log reduction in viable bacteria count in time-kill assay ranged between 6 Log10 cfu/mL to zero after 24 h of incubation with BZT nanoparticle.

  4. 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.

  5. Electromechanical Response of Polycrystalline Barium Titanate Resolved at the Grain Scale

    DEFF Research Database (Denmark)

    Majkut, Marta; Daniels, John E.; Wright, Jonathan P.

    2017-01-01

    critical for understanding bulk polycrystalline ferroic behavior. Here, three-dimensional X-ray diffraction is used to reconstruct a 3D grain map (grain orientations and neighborhoods) of a polycrystalline barium titanate sample and track the grain-scale non-180° ferroelectric domain switching strains...

  6. 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...

  7. Barium titanate-polymer composites produced via directional freezing.

    Science.gov (United States)

    Gorzkowski, Edward P; Pan, Ming-Jen

    2009-08-01

    In this study, we use a freeze casting technique to construct ceramic-polymer composites in which the 2 phases are arranged in an electrically parallel configuration. By doing so, the composites exhibit dielectric constant (K) up to 2 orders of magnitude higher than that of composites with ceramic particles randomly dispersed in a polymer matrix. In this technique, an aqueous ceramic slurry was frozen unidirectionally to form ice platelets and ceramic aggregates that were aligned in the temperature gradient direction. Upon freeze-drying, the ice platelets sublimed and left the lamellar ceramic structure intact. The green ceramic body was fired to retain the microstructure, and then the space between ceramic lamellae was infiltrated with a polymer material. The finished composites exhibit the high dielectric constant (1000) of ferroelectric ceramics while maintaining the unique properties of polymer materials such as graceful failure, low dielectric loss, and high dielectric breakdown.

  8. 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.

  9. Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium-Air Batteries

    Science.gov (United States)

    2014-11-01

    Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium -Air Batteries by Claire Weiss Brennan, Victoria Blair...Ground, MD 21005-5069 ARL-TR-7145 November 2014 Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium -Air...COVERED (From - To) 1 June–31 August 2014 4. TITLE AND SUBTITLE Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium

  10. A Study on Reactive Ion Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur Hexafluoride (SF6)

    Science.gov (United States)

    2014-07-01

    A Study on Reactive Ion Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur...Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur Hexafluoride (SF6) Samuel G...Study on Reactive Ion Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur Hexafluoride

  11. Electrical properties of thick film capacitors based on barium titanate glass formulations

    Energy Technology Data Exchange (ETDEWEB)

    Leppaevuori, S.; Uusimaeki, A.; Hannula, T.

    1981-12-18

    We carried out an investigation of the effects of the glass content of the dielectric layer of thick film capacitors with a barium titanate glass formulation on the capacitance density, loss factor and breakdown voltage of the capacitors. These effects were studied by varying the firing temperature and glass content of the dielectric paste and by using different types of electrode paste. The characteristics of a test capacitor were also measured.

  12. 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.

  13. 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.

  14. Influence of Barium Hexaferrite on Magnetic Properties of Hydroxyapatite Ceramics.

    Science.gov (United States)

    Jarupoom, P; Jaita, P

    2015-11-01

    Hydroxyapatite (HA) powders was derived from natural bovine bone by sequence of thermal processes. The barium hexaferrite (BF) find magnetic powders were added into HA powders in ratio of 1-3 vol.%. The HA-BF ceramics were prepared by a solid state reaction method and sintered at 1250 degrees C for 2 h. Effects of BF additive on structural, physical and magnetic properties of HA ceramics were investigated. X-ray diffraction revealed that all HA-BF samples showed a main phase of high purity hydroxyapatite [Ca10(PO4)6(OH)2] with calcium and phosphate molar ratio of 1.67. The addition of BF into HA inhibited grain growth and caused an improvement of mechanical properties. The M-H hysteresis loops also showed an improvement in magnetic behavior for higher content of BF. Moreover, in vitro bioactivity test indicated that the 2-3 vol.% sample may be suitable for biological applications.

  15. 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.

  16. Characterization and microstructure of porous lead zirconate titanate ceramics

    Indian Academy of Sciences (India)

    B Praveenkumar; H H Kumar; D K Kharat

    2005-08-01

    Porous lead zirconate titanate (PZT) ceramics are widely used because of their low acoustic impedance, high figure of merit and high hydrostatic sensitivity. In the present work, porous PZT ceramics were fabricated by incorporating polyethylene oxide (PEO) as pore-forming agent. Both PZT powder and PEO were mixed with a binder at different ratios and compaction was carried out. The samples were slowly heated to remove the pore-forming agent and binder without cracks, followed by controlled sintering and electrode forming. Samples were poled using corona poling technique. The ferroelectric properties and microstructure of the prepared ceramics were characterized. The correlation of porosity with microstructure and ferroelectric properties were discussed.

  17. Characterization Micro/Nanostructures of Barium Strontium Titanate

    OpenAIRE

    Abdelhalim Elbasset; Farid Abdi; Taj-Dine Lamcharfi; Nor-Said Echatoui

    2016-01-01

    Structural characteristics of Ba0.0975S0.025TiO3 (BS0.025T) ceramics calcined at different temperatures at 800, 850 and 900°C for 4 hours hove been investigated. Results DRX showed that the change in the cell parameter along a axis (a) is more important than that along c axis and is accompanied by spacing of these parameters. In addition they indicate that the diminuation of symmetry is caused by the increase of the calcination temperature This trend towards the tetragonale phase was confir...

  18. Effects of oxygen vacancies on polarization stability of barium titanate

    Science.gov (United States)

    Wang, Jun; Shen, YaoGen; Song, Fan; Ke, FuJiu; Bai, YiLong; Lu, ChunSheng

    2016-03-01

    Oxygen vacancy, a kind of native point defects in ferroelectric ceramics, usually causes an increase of the dielectric loss. Based on experimental observations, it is believed that all of the oxygen vacancies are an unfavorable factor for energy saving. By using molecular dynamics simulations, we show that the increase of coercive and saturated electric fields is due to the difficulty to switch local polarization near an oxygen vacancy, and so that a ferroelectric device has to sustain the rising consumption of energy. The simulation results also uncover how oxygen vacancies influence ferroelectric properties.

  19. 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.

  20. 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.

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

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2013-01-01

    domains from the in-plane to out-of-plane orientation provides the change of the refractive index, which can be exploited for effective light modulation. By numerical analysis we prove that the π phase change can be achieved with a 12…15μm length device having propagation losses 0.05…0.2dB/μm.......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...

  2. 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.

  3. 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.

  4. Enhanced Sensitivity of Surface Plasmon Resonance Sensor Based on Bilayers of Silver-Barium Titanate

    Directory of Open Access Journals (Sweden)

    S. Fouad

    2016-12-01

    Full Text Available Surface plasmon resonance (SPR sensors have been widely adopted with various fields such as physics, chemistry, biology and biochemistry. SPR sensor has many advantages like the less number of sensing samples required, freedom of electromagnetic interference and higher sensitivity. This research investigates the phase interrogation technique of a surface plasmon resonance sensor based on silver and thin film dielectric material of Barium titanate layers. Barium titanate (BaTiO3 layer is adopted due to its excellent dielectric properties such as high dielectric constant and low dielectric loss. The numerical results demonstrate that the fusion of the proposed material BaTiO3 layer into surface plasmon resonance sensor yields a higher sensitivity of 280 degree/RIU in comparison with surface plasmon resonance sensor without BaTiO3 layer which shows only a sensitivity of 120 degree/RIU. As the thickness of this layer increases from 5 nm to 10 nm, the sensitivity is enhanced from 160 degree/RIU to 280 degree/RIU for a fixed metal layer of silver with a thickness of (70 nm.

  5. Nanostructured Barium Titanate/Carbon Nanotubes Incorporated Polyaniline as Synergistic Electromagnetic Wave Absorbers

    Directory of Open Access Journals (Sweden)

    Lujun Yu

    2016-01-01

    Full Text Available The three-dimensional (3D conductive network structures formed by barium titanate/carbon nanotubes incorporated polyaniline were favorable for strengthening electromagnetic absorption capability. Herein, an easy and flexible method consisting of sol-gel technique, in situ polymerization, and subsequent mechanical method have been developed to prepare the barium titanate/carbon nanotubes incorporated polyaniline (CNTs/BaTiO3/PANI or CBP ternary composites. The dielectric properties and microwave absorption properties of CNTs/BaTiO3/PANI composites were investigated in the frequency range of 2–18 GHz by vector network analyzer. Interestingly, it is found that the CNTs/BaTiO3/PANI composites with 3D conductive network structures presented outstanding electromagnetic absorption properties, which may be attributed to the high impedance matching behavior and improved dielectric loss ability and novel synergistic effect. Additionally, it also can be supposed that the “geometrical effect” of composite was more beneficial to absorbing the incident electromagnetic wave. The CNTs/BaTiO3/PANI composite (the mass ratio of CNTs/BaTiO3 to PANI is 2 : 3 exhibits the best microwave absorption properties, of which the minimum reflection loss value can reach −30.9 dB at 8 GHz and the absorption bandwidth with a reflection loss blew −10 dB ranges from 7.5 to 10.2 GHz.

  6. 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.

  7. 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...

  8. 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)

  9. Pressure effects during pulsed-laser deposition of barium titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalo, J.; Afonso, C.N. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Optica; Gomez San Roman, R.; Perez Casero, R. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain); Perriere, J. [Groupe de Physique des Solides, Universites Paris VII et VI, URA 17 du CNRS, Tour 23, 2 Place Jussieu, 75251 Paris Cedex 05 (France)

    1998-05-01

    The composition and homogeneity of barium titanate films grown by pulsed-laser deposition at different substrate temperatures (room temperature, 700 C) and gas environments (O{sub 2},Ar) in a broad pressure range (10{sup -7}-1 mbar) are correlated to the plasma expansion dynamics. It is found that the deposited films present an excess of Ba in the intermediate pressure range (10{sup -2}

  10. Barium Strontium Titanate Thin Film Growth with rotational speed variation as a satellite temperature sensor prototype

    Science.gov (United States)

    Mulyadi; Rika, W.; Sulidah; Irzaman; Hardhienata, Hendradi

    2017-01-01

    Barium Strontium Titanate(BST) is a promising material for sensor devices such as temperature and infrared sensor. BaxSr1-xTiO3 thin films with affordable Si substrate were prepared by chemical solution deposition method and spin coating technique for 30 seconds with variation in rotation speed (3000 rpm, 5500 rpm and 8000 rpm). A high baking temperature at 8500C has been used for 15 hours during the annealing process. The thickness of BST film was calculated via gravimetric calculation. USB 2000 VIS-NIR was used to characterize the optical properties of BST thin film. The obtained reflectance curve showed that the most reflected wavelengths were in the range of 408-452 nm respectively. The result of the optical film characterization is very important for further development as a sensor in satellite technology.

  11. 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)

  12. 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].

  13. Low-temperature anharmonicity of barium titanate: A path-integral molecular-dynamics study

    Science.gov (United States)

    Geneste, Grégory; Dammak, Hichem; Hayoun, Marc; Thiercelin, Mickael

    2013-01-01

    We investigate the influence of quantum effects on the dielectric and piezoelectric properties of barium titanate in its (low-temperature) rhombohedral phase, and show the strongly anharmonic character of this system even at low temperature. For this purpose, we perform path-integral molecular-dynamics simulations under fixed pressure and fixed temperature, using an efficient Langevin thermostat-barostat, and an effective Hamiltonian derived from first-principles calculations. The quantum fluctuations are shown to significantly enhance the static dielectric susceptibility (≈ by a factor of 2) and the piezoelectric constants, reflecting the strong anharmonicity of this ferroelectric system even at very low temperature. The slow temperature-evolution of the dielectric properties observed below ≈100 K is attributed (i) to zero-point energy contributions and (ii) to harmonic behavior if the quantum effects are turned off.

  14. 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.

  15. 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.

  16. Study of a Flexible Low Profile Tunable Dipole Antenna Using Barium Strontium Titanate Varactors

    Science.gov (United States)

    Cure, David; Weller, Thomas; Miranda, Felix A.

    2014-01-01

    In this paper a flexible low profile dipole antenna using a frequency selective surface (FSS) with interdigital barium strontium titanate (BST) varactor-tuned unit cells is presented. The varactor chips were placed only along one dimension of the FSS to avoid the use of vias and simplify the DC bias network. The antenna uses overlapping metallic plates that resemble fish scales as a ground plane to improve the flexibility of the multi-material stack structure. The measured data of the antenna demonstrate tunability from 2.42 GHz to 2.66 GHz and 1.3 dB gain drop when using overlapping metallic plates instead of continuous ground plane. The total antenna thickness is approximately lambda/24.

  17. 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 ...

  18. 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.

  19. 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.

  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. 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.

  2. 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.

  3. 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.

  4. Lead-barium fluoroborate glass ceramics doped with Nd3+ or Er3+

    Science.gov (United States)

    Petrova, O. B.; Sevostjanova, T. S.; Anurova, M. O.; Khomyakov, A. V.

    2016-02-01

    Lead-barium fluoroborate glasses in the PbF2-BaF2-B2O3, PbF2-BaO-B2O3, and PbO- BaF2-B2O3 systems doped with rare-earth ions (Nd3+ or Er3+) are synthesized and studied. It is shown that, based on these glasses, it is possible to produce transparent glass ceramics with fluoride crystalline phases, including ceramics with one crystalline phase of the fluorite structure. The spectral and luminescent properties of the doped glasses, glass ceramics, and polycrystalline complex fluorides containing Pb, Ba, and rare ions are studied.

  5. Hydrothermal synthesis and dielectric properties of lanthanum titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Yuan; NAN Ce-wen

    2005-01-01

    Lanthanum titanate (La2/3TiO3) powders were synthesized by hydrothermal method based on the reaction of TiO2, La(NO3 )3 and KOH at 160 ℃ for 24 h followed by the treatment of acidification. The microstructure,morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope,transmission electron microscope and impedance method. The results show that the La2/3 TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1 150 ℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.

  6. 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

  7. Particularities of Radiation Defect Formation in Ceramic Barium Cerate

    Science.gov (United States)

    Khromushin, I. V.; Aksenova, T. I.; Tuseev, T.; Munasbaeva, K. K.; Ermolaev, Yu V.; Ermolaev, V. N.; Seitov, A. S.

    2015-04-01

    The effects of irradiation with electrons, ions of noble gases (Ne, Ar, Kr) and oxygen on the structure and properties of neodymium-doped barium cerate have been studied using the methods of X-ray diffraction analysis, scanning electron and atomic force microscopy, thermal desorption spectroscopy. It was shown that irradiation by low-energy ions of noble gases stimulates the blistering processes on the sample surface, while the high-energy ions contribute to formation of the structures on the irradiated surface that resemble the various stages of spherulitegrowth. The similar structures were not observed in the case of irradiation with high-energy oxygen ions. According to the data on thermal desorption of water and oxygen molecules from the irradiated barium cerate it was supposed that irradiation by the noble gas ions promotes neodymium oxidation state change. It was noticed that the electron irradiation leads to the formation of the nano-sized acicular structures on the cerate surface.

  8. Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

    Energy Technology Data Exchange (ETDEWEB)

    Siddabattuni, Sasidhar [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Schuman, Thomas P., E-mail: tschuman@mst.edu [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Missouri University of Science and Technology, Materials Science and Engineering Department, 1400N. Bishop Avenue, Rolla, MO 65409 (United States)

    2011-11-15

    Highlights: > A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. > A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T{sub g} measurements. > Composite T{sub g} was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. > A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. > The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity {approx}6.3 and at a 30 {mu}m thickness achieved a calculated energy density of 4.6 J/cm{sup 3}.

  9. 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.

  10. First-principles study of lattice dynamics, structural phase transition, and thermodynamic properties of barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huai-Yong; Zhao, Ying-Qin; Lu, Qing [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Zeng, Zhao-Yi [Chongqing Normal Univ. (China). College of Physics and Electronic Engineering; Chinese Academy of Engineering Physics, Mianyang (China). National Key Laboratory for Shock Wave and Detonation Physics Research; Cheng, Yan [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Sichuan Univ., Chengdu (China). Key Laboratory of High Energy Density Physics and Technology of Ministry of Education

    2016-11-01

    Lattice dynamics, structural phase transition, and the thermodynamic properties of barium titanate (BaTiO{sub 3}) 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 BaTiO{sub 3} 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 BaTiO{sub 3} among four phases and the thermodynamic properties of BaTiO{sub 3} 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 α{sub V}, heat capacity C{sub V}, Grueneisen parameter γ, and bulk modulus B of the rhombohedral phase BaTiO{sub 3} are estimated from 0 K to 200 K.

  11. 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.

  12. Assessment of full ceramic solid oxide fuel cells based on modified strontium titanates

    DEFF Research Database (Denmark)

    Holtappels, Peter; Ramos, Tania; Sudireddy, Bhaskar Reddy;

    2014-01-01

    stimulated the development for full ceramic anodes based on strontium titanates. Furthermore, the Ni-cermet is primarily a hydrogen oxidation electrode and efficiency losses might occur when operating on carbon containing fuels. In the European project SCOTAS-SOFC full ceramic cells comprising CGO...

  13. Barium titanate tape properties for MLCC application using different binder systems

    Science.gov (United States)

    Yoon, Dang-Hyok

    Most of multilayer ceramic capacitor (MLCC) industries are currently using solvent-based slip systems, although water-based slips have been receiving increasing attention due to reduced health and environmental hazards. The current work focuses on two main fields to meet the challenges in MLCC processing in aqueous media. One is the comparison between water- and solvent-based slip systems using design of experiments (DOE). The other is the understanding of Ba2+ ion leaching behavior in water and its effect on tape properties. For the first part, twenty four kinds of BaTiO3 slips were investigated using three different binder systems: one solvent-based, and two water-based systems. Tape casting, sintering and characterization were conducted. Slip viscosity and tape strength of the green tape depended significantly on the binder type. It was possible to achieve a higher green density for water-based system than that for a solvent-based one. Most of the green body properties from solvent-based system depended on the ceramic powder. On the other hand, the dispersant was the most significant factor for the green body properties of two water-based systems. Sintered properties such as microstructure and dielectric permittivity for three systems depended significantly on the type of ceramic powder. An optimization was performed for each system by means of a scorecard. By choosing the optimum condition, comparable results were drawn for the water-based system compared to a solvent-based one for MLCC application. For the second part, the amount of Ba2+ ion leaching from BaTiO3 in water was determined by an EDTA titration method. The greater extent and the faster rate of Ba2+ leaching were found at the lower solution pH. The excess free barium ions expressed by means of the Ba/Ti ratio adversely affected most tape properties. To passivate BaTiO 3 surface from Ba2+ ion leaching in water, passivation agent layer (PAL) was formed by drying the slurry after adding a commercial

  14. Corrosion behavior of pyroclore-rich titanate ceramics for plutonium disposition ; impurity effects.

    Energy Technology Data Exchange (ETDEWEB)

    Bakel, A. J.

    1999-01-13

    The baseline ceramic contains Ti, U, Ca, Hf, Gd, and Ce, and is made up of only four phases, pyrochlore, zirconolite, rutile, and brannerite. The impurities present in the three other ceramics represent impurities expected in the feed, and result in different phase distributions. The results from 3 day, 90 C MCC-1 tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics alters the phase distributions, which in turn, affects the corrosion behavior.

  15. Zirconia doped barium titanate induced electroactive β polymorph in PVDF-HFP: high energy density and dielectric properties

    Science.gov (United States)

    Sharma, Maya; Ranganatha, S.; Kalyani, Ajay Kumar; Ranjan, Rajeev; Madras, Giridhar; Bose, Suryasarathi

    2014-12-01

    Zirconium-doped barium titanate (BZT-08, Ba(Ti0.92 Zr0.08)O3) particles were synthesized and PVDF-HFP-based composites were prepared by melt mixing to design materials with tunable dielectric and ferroelectric properties. Composites of PVDF-HFP and barium titanate (BT) particles were also prepared to realize the exceptional properties associated with the BZT-08-like stabilization of two ferroelectric phases, i.e. tetragonal and orthorhombic at room temperature. To facilitate the uniform dispersion and interfacial adhesion with the matrix, the particles were modified with (3-aminopropyl) triethoxysilane. The dependence of the dielectric and ferroelectric properties of the as-prepared composites were systematically investigated in this study with respect to a wide range of frequencies. The composites with BZT-08 exhibited the significantly high dielectric permittivity of ca. 26 (at 100 Hz) and a high energy density (2.7 J cm-3 measured on 100 μm thick film) at room temperature with respect to the control PVDF-HFP and PVDF-HFP/BT composites. Interestingly, the BZT-08 particles facilitated the electroactive β polymorph in the PVDF-HFP and enhanced polarization in the composites, leading to improved ferroelectric properties in the composites.

  16. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    Energy Technology Data Exchange (ETDEWEB)

    Selling, J.

    2007-07-01

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl{sub 2} nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI{sub 2} is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu{sup 2+}/Eu{sup 3+} ratio in the glass ceramics should be determined and optimize favor of the Eu{sup 2+}. We also want to distinguish between Eu{sup 2+} in the glass matrix and Eu{sup 2+} in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a

  17. 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.

  18. 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)

  19. Molecular structures of (3-aminopropyl)trialkoxysilane on hydroxylated barium titanate nanoparticle surfaces induced by different solvents and their effect on electrical properties of barium titanate based polymer nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yanyan; Wang, Guanyao; Huang, Xingyi, E-mail: xyhuang@sjtu.edu.cn; Bu, Jing; Sun, Xiaojin; Jiang, Pingkai

    2016-02-28

    Graphical abstract: - Highlights: • The silanization on the surface of hydroxylated barium titanate nanoparticles was introduced by using two kinds of trialkoxysilanes with different solvents (toluene and ethanol), respectively. • Solvents have more remarkable impact on the dielectric properties of the subsequent BT/PVDF nanocomposites than the types of silanes. • The solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. - Abstract: Surface modification of nanoparticles by grafting silane coupling agents has proven to be a significant approach to improve the interfacial compatibility between inorganic filler and polymer matrix. However, the impact of grafted silane molecular structure after the nanoparticle surface modification, induced by the utilized solvents and the silane alkoxy groups, on the electrical properties of the corresponding nanocomposites, has been seldom investigated. Herein, the silanization on the surface of hydroxylated barium titanate (BT-OH) nanoparticles was introduced by using two kinds of trialkoxysilane, 3-aminopropyltriethoxysilane (AMEO) and 3-aminopropyltrimethoxysilane (AMMO), with different solvents (toluene and ethanol), respectively. Solid-state {sup 13}C, {sup 29}Si nuclear magnetic resonance (NMR) spectroscopy and high-resolution X-ray photoelectron spectroscopy (XPS) were employed to validate the structure differences of alkoxysilane attachment to the nanoparticles. The effect of alkoxysilane structure attached to the nanoparticle surface on the dielectric properties of the BT based poly(vinylidene fluoride) (PVDF) nanocomposites were investigated. The results reveal that the solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. Nevertheless, the alkoxy groups of silane show a marginal influence on the dielectric properties of the nanocomposites. These research results

  20. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Science.gov (United States)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  1. 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.

  2. Preparation and characterization of nanocrystalline barium ferrite ceramic

    Science.gov (United States)

    Saeedi, Majid; Abdellahi, Majid; Rahimi, Alireza; Khandan, Amirsalar

    2016-09-01

    In this work, nanocrystalline BaFe12O19 hexaferrite ceramic was synthesized via high-energy ball milling and subsequent sintering from the mixed powders of Fe2O3 and BaCO3. X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), differential thermal analysis (DTA) and scanning electron microscopy (SEM) were utilized to understand the structural evolution during the synthesis process. Vibrating sample magnetometer (VSM) was also used to investigate the magnetic properties of the samples as a function of sintering process. DTA analysis suggested that the initial high-energy milling of the precursors helps the formation of single domain magnetic particles. According to the results obtained, BaFe12O19 can be formed via two main steps, during which BaFe2O4 is formed initially that eventually turns into BaFe12O19. VSM-based findings showed that the ratio of remanent magnetization to magnetization value (Mr/Ms) is around 0.5 which is the expected value for randomly oriented assembly of uniaxial single-domain particles undergoing magnetization reversal by coherent rotation. The observed magnetic parameters (Mr and Ms) are much higher than the previously reported values, due to the reduction in particle size as a result of ball milling.

  3. Full Ceramic Fuel Cells Based on Strontium Titanate Anodes, An Approach Towards More Robust SOFCs

    DEFF Research Database (Denmark)

    Holtappels, Peter; Irvine, J.T.S.; Iwanschitz, B.;

    2013-01-01

    The persistent problems with Ni-YSZ cermet based SOFCs, with respect to redox stability and tolerance towards sulfur has stimulated the development of a full ceramic cell based on strontium titanate(ST)- based anodes and anode support materials, within the EU FCH JU project SCOTAS-SOFC. Three...

  4. Dielectric and Piezoelectric Properties of Sodium Bismuth Titanate Ceramics with KCe Substitution

    Institute of Scientific and Technical Information of China (English)

    XU Jian-Xiu; ZHAO Liang; ZHANG Cheng-Ju

    2008-01-01

    @@ The piezoelectric properties of the (KCe)-substituted sodium bismuth titanate (Na0.5Bi4.5 Ti4O15, NBT) piezo-electric ceramics are investigated. The piezoelectric properties of NBT ceramics are significantly enhanced by (KCe) substitution. The Curie temperature Tc, and piezoelectric coefficient d33 for the (KCe)-substituted NBT are found to be 663°C, and 27pC/N, respectively. Dielectric and annealing spectroscopy present that the (KCe) co-substituted NBT piezoelectric ceramics possess stable piezoelectric properties.

  5. 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

  6. Effect of annealing time, weight pressure and cobalt doping on the electrical and magnetic behavior of barium titanate

    Science.gov (United States)

    Samuvel, K.; Ramachandran, K.

    2016-05-01

    BaTi0.5CO0.5O3 (BTCO) nanoparticles were prepared by the solid state reaction technique using different starting materials and the microstructure examined by XRD, FESEM, BDS and VSM. X-ray diffraction and electron diffraction patterns showed that the nanoparticles were the tetragonal BTCO phase. The BTCO nanoparticles prepared from the starting materials of as prepared titanium-oxide, Cobalt -oxide and barium carbonate have spherical grain morphology, an average size of 65 nm and a fairly narrow size distribution. The nano-scale presence and the formation of the tetragonal perovskite phase as well as the crystallinity were detected using the mentioned techniques. Dielectric properties of the samples were measured at different frequencies. Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. The doped BTCO samples exhibited low loss factor at 1 kHz and 1 MHz frequencies respectively.

  7. Molecular structures of (3-aminopropyl)trialkoxysilane on hydroxylated barium titanate nanoparticle surfaces induced by different solvents and their effect on electrical properties of barium titanate based polymer nanocomposites

    Science.gov (United States)

    Fan, Yanyan; Wang, Guanyao; Huang, Xingyi; Bu, Jing; Sun, Xiaojin; Jiang, Pingkai

    2016-02-01

    Surface modification of nanoparticles by grafting silane coupling agents has proven to be a significant approach to improve the interfacial compatibility between inorganic filler and polymer matrix. However, the impact of grafted silane molecular structure after the nanoparticle surface modification, induced by the utilized solvents and the silane alkoxy groups, on the electrical properties of the corresponding nanocomposites, has been seldom investigated. Herein, the silanization on the surface of hydroxylated barium titanate (BT-OH) nanoparticles was introduced by using two kinds of trialkoxysilane, 3-aminopropyltriethoxysilane (AMEO) and 3-aminopropyltrimethoxysilane (AMMO), with different solvents (toluene and ethanol), respectively. Solid-state 13C, 29Si nuclear magnetic resonance (NMR) spectroscopy and high-resolution X-ray photoelectron spectroscopy (XPS) were employed to validate the structure differences of alkoxysilane attachment to the nanoparticles. The effect of alkoxysilane structure attached to the nanoparticle surface on the dielectric properties of the BT based poly(vinylidene fluoride) (PVDF) nanocomposites were investigated. The results reveal that the solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. Nevertheless, the alkoxy groups of silane show a marginal influence on the dielectric properties of the nanocomposites. These research results provide important insights into the fabrication of advanced polymer nanocomposites for dielectric applications.

  8. Water-Induced Degradation in Lead Zinc Niobate-Lead Zirconate Titanate Soft Piezoelectric Ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Xiang-Ping; CHEN Wan-Ping; PENG Zhi; ZENG Min; CHANWANG Li-Hua; YIN Qing-Rui

    2005-01-01

    @@ Water-induced degradation of lead zinc niobate-lead zirconate titanate (Pb(Zn1/3Nb2/3)O3-Pb(ZrTi)O3) soft piezoelectric ceramics is studied using electrochemical hydrogen charging, in which the silver electrodes of the piezoelectric ceramics constitute a cathode in 0.01-M NaOH solution to evolve hydrogen by electrolysis of water.It is found that with the increasing hydrogen charging time, the resonance impedance increases, the difference between the resonance frequency and the anti-resonance frequency decreases, the spontaneous polarization, the remanent polarization and the piezoelectric coefficient d33 decrease. The degradation behaviour of the soft piezoelectric ceramics can be explained to hydrogen incorporating into the lattice and forming hydroxy (OH-)bonds in the perovskite structure, which prevents the Ti ions from switching and increases the coercive field Ec.The degradation characteristics of the soft piezoelectric ceramics are quite different from that of lead zirconate titanate hard piezoelectric ceramics.

  9. A promising lightweight multicomponent microwave absorber based on doped barium hexaferrite/calcium titanate/multiwalled carbon nanotubes

    Science.gov (United States)

    Afghahi, Seyyed Salman Seyyed; Jafarian, Mojtaba; Atassi, Yomen

    2016-07-01

    We present the design of a microwave absorber in the X band based on ternary nanocomposite of doped barium hexaferrite (Ba-M)/calcium titanate (CTO)/multiwall carbon nanotubes (MWCNTs) in epoxy matrix. The hydrothermal method has been used to synthesize Ba-M and CTO nanopowder. The phase identification has been investigated using XRD patterns. Scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, and vector network analyzer are used to analyze the morphology of the different components and the magnetic, electromagnetic, and microwave absorption properties of the final composite absorbers, respectively. As far as we know, the design of this type of multicomponent microwave absorber has not been investigated before. The results reveal that the combination of these three components with their different loss mechanisms has a synergistic effect that enhances the attenuation properties of the final composite. The absorber of only 2.5-mm thickness and 35 wt% of loading ratio exhibits a minimum reflection loss of -43 dB at 10.2 GHz with a bandwidth of 3.6 GHz, while the corresponding absorber based on pure (Ba-M) shows a minimum reflection loss of -34 dB at 9.8 GHz with a bandwidth of 0.256 GHz and a thickness of 4 mm.

  10. Rhodium-doped barium titanate perovskite as a stable p-type semiconductor photocatalyst for hydrogen evolution under visible light.

    Science.gov (United States)

    Maeda, Kazuhiko

    2014-02-12

    Rhodium-doped barium titanate (BaTiO3:Rh) powder was prepared by the polymerized complex (PC) method, and the photocatalytic activity for H2 evolution from water was examined. BaTiO3 is a wide-gap n-type semiconductor having a band gap of 3.0 eV. Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region. Upon visible light (λ > 420 nm), BaTiO3:Rh modified with nanoparticulate Pt as a water reduction promoter was capable of producing H2 from water containing an electron donor such as methanol and iodide. The best material prepared by the PC method exhibited higher activity than that made by a conventional solid-state reaction method. Visible-light-driven Z-scheme water splitting was also accomplished using Pt/BaTiO3:Rh as a building block for H2 evolution in combination with PtOx-loaded WO3 as an O2 evolution photocatalyst in the presence of an IO3(-)/I(-) shuttle redox mediator. Photoelectrochemical analysis indicated that a porous BaTiO3:Rh electrode exhibited cathodic photoresponse due to water reduction in a neutral aqueous Na2SO4 solution upon visible light.

  11. Measurement of Elastic Modulus of Alumina and Barium Strontium Titanate Wafers Produced by Tape Casting Method

    Science.gov (United States)

    2014-02-01

    measurements – Generally in the 230 to 250 GPa range * VTT manufacturing, 1996, ISBN 951-38-4987-2 Figure 7 Modulus measurements on 0.5-mm wafers of...Capacitors,”1998 Society of Automotive Engineers. 4. Barsoum, Michel, “Fundamentals of Ceramics,” cap.11, p. 401. 5. VTT Manufacturing, ISBN 951-38

  12. Titan

    Science.gov (United States)

    Müller-Wodarg, Ingo; Griffith, Caitlin A.; Lellouch, Emmanuel; Cravens, Thomas E.

    2014-03-01

    Introduction I. C. F. Müller-Wodarg, C. A. Griffith, E. Lellouch and T. E. Cravens; Prologue 1: the genesis of Cassini-Huygens W.-H. Ip, T. Owen and D. Gautier; Prologue 2: building a space flight instrument: a P.I.'s perspective M. Tomasko; 1. The origin and evolution of Titan G. Tobie, J. I. Lunine, J. Monteux, O. Mousis and F. Nimmo; 2. Titan's surface geology O. Aharonson, A. G. Hayes, P. O. Hayne, R. M. Lopes, A. Lucas and J. T. Perron; 3. Thermal structure of Titan's troposphere and middle atmosphere F. M. Flasar, R. K. Achterberg and P. J. Schinder; 4. The general circulation of Titan's lower and middle atmosphere S. Lebonnois, F. M. Flasar, T. Tokano and C. E. Newman; 5. The composition of Titan's atmosphere B. Bézard, R. V. Yelle and C. A. Nixon; 6. Storms, clouds, and weather C. A. Griffith, S. Rafkin, P. Rannou and C. P. McKay; 7. Chemistry of Titan's atmosphere V. Vuitton, O. Dutuit, M. A. Smith and N. Balucani; 8. Titan's haze R. West, P. Lavvas, C. Anderson and H. Imanaka; 9. Titan's upper atmosphere: thermal structure, dynamics, and energetics R. V. Yelle and I. C. F. Müller-Wodarg; 10. Titan's upper atmosphere/exosphere, escape processes, and rates D. F. Strobel and J. Cui; 11. Titan's ionosphere M. Galand, A. J. Coates, T. E. Cravens and J.-E. Wahlund; 12. Titan's magnetospheric and plasma environment J.-E. Wahlund, R. Modolo, C. Bertucci and A. J. Coates.

  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. 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.

  15. Aging Effect on Lanthanum Doped Ferroelectric Lead Titanate Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ferroelectric devices are widely applied in many fields, such as energy conversion and communication. The aging effect in ferroelectric materials plays a central role in the reliability of the related equipments. But it is very difficult to understand the origin of aging effect in ferroelectrics because these materials possess different defects and exhibit various aging behavior. The reverse transition temperature in lead titanate doped with lanthanum increases during aging at ferroelectric phase was reported. It is well known that lattice defects, such as vacancies and solute atoms, are ubiquitous in crystalline solids. These point defects affect physical properties in ferroelectrics significantly. The abnormal increase of the reverse transition temperature was discussed in terms of diffusion of point defects during aging. Dielectric performance in the material after aging was measured and discussed as well.

  16. 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.

  17. 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.

  18. 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.

  19. Study on the Structure and Dielectric Properties of ZnO and Nb 2 O 5 Co-doped Barium Strontium Titanate Ceramics%ZnO和Nb2O5共掺杂钛酸锶钡陶瓷的结构及其介电性能研究

    Institute of Scientific and Technical Information of China (English)

    王俊岭; 周恒为; 马晓娇; 丁捷; 徐凡华; 衡晓; 雷婷; 尹红梅

    2014-01-01

    ZnO and Nb2O5 co-doped Ba0.2Sr0.8TiO3 ceramics were prepared by the method of solid state reaction. Crystalline structures and complex dielectric constant were measured by X-ray diffraction and dielectric spectra, respectively. The results show that:1) Zinc ions (Zn2+) and Niobium ion (Nb5+) enter the crystal lattice of Ba0.2Sr0.8TiO3 perovskite, and the ceramics have pure structure; 2) with the increase of Nb2O5 contents, the typical dispersion phase transition turns into the relaxation phase transition at low temperature, and a new relaxation processes has been found in the range of 300K-360K; 3) when doped certain amount of ZnO, the dielectric constant decreases and the dielectric loss increases at room temperature with the increasing of Nb 2 O 5 content.%采用固相反应法制备了ZnO、Nb 2 O 5共掺杂Ba 0.2 Sr 0.8 TiO 3陶瓷材料,并用X射线衍射(XRD)和介电谱方法,分别对系列陶瓷样品的结构和复介电常数进行了测量.结果表明:1)Zn2+、Nb5+进入Ba 0.2 Sr 0.8 TiO 3晶格后仍然为钙钛矿型固溶体;2)Nb 2 O 5会使得材料的低温弥散相变过程转变为弛豫相变过程,并在300~360K区域内会出现新的弛豫过程;3)掺入一定量的ZnO后Nb2O5掺入降低了Ba 0.2 Sr 0.8 TiO 3陶瓷材料的介电常数,增大了其介电损耗.

  20. 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

  1. Semiconducting and dielectric properties of barium titanates, tantalates and niobates with perovskite structure

    Science.gov (United States)

    Kolodiazhnyi, Taras

    The dielectric and semiconducting properties of two types of ceramics (n-type BaTiO3 and dielectric Ba(B'1/3 B″2/3)O3 where B' = Mg, Zn, Ni, and B″ = Nb, Ta) were characterized. Complex impedance analysis and dc conductivity measurements of samples prepared at various PO2 have ruled out oxygen chemisorption in favor of interfacial segregation of cation vacancies as the cause of the positive temperature coefficient of resistivity (PTCR) effect in n-type BaTiO3. The effect of preparation conditions, sintering atmosphere, stoichiometry, and post-sinter anneal on the defect chemistry of BaTiO3 was studied using the electron paramagnetic resonance (EPR) technique. Several paramagnetic defects such as, Ti3+, VBa, and VTi were detected and identified by EPR. Current-voltage characteristics (I-V) of PTCR BaTiO 3 were analyzed in light of space-charge-limited-current, trap-filled-limited-current, Frenkel-Poole, small polaron, and double-Schottky barrier models. It was shown that for the double-Schottky barrier model, a partial stabilisation of the potential barrier is expected when the Fermi level is pinned at grain boundaries by a high density of the interface states. The deviation of I-V characteristics of BaTiO3 in the region of the PTCR effect can be explained by dependence of the population of the interface electron states on applied voltage. Based on the Seebeck and Hall effect measurements, it was found that in the range of 100--300 K, the drift mobility of electrons in BaTiO 3 is not thermally activated, which supports the concept of conduction band electron transport rather than small radii polaron hopping. However, further study over a wider temperature range and on better quality crystals is required to unequivocally clarify the electron transport mechanism in BaTiO 3. Phase composition, degree of cation ordering, and dielectric properties of complex perovskites with general formula Ba(B' 1/3B″2/3)O3 where B' = Mg, Zn, Ni, and B″ = Nb, Ta were analyzed

  2. Direct probing of semiconductor barium titanate via electrostatic force microscopy Sondagem direta de titanato de bário semicondutorpor meio de microscopia de força eletrostática

    Directory of Open Access Journals (Sweden)

    S. M. Gheno

    2007-06-01

    Full Text Available Electrostatic force microscopy (EFM was used to directly probe surface potential in doped barium titanate semiconducting ceramics. EFM measurements were performed using noncontact scans at a constant tip-sample separation of 75 nm with varied bias voltages applied to the sample. The applied voltage was mapped up to 10 V and the distribution of potential across the sample showed changes in regions that matched the grain boundaries, displaying a constant barrier width of 145.2 nm.A microscopia de força eletrostática (EFM foi usada para sondagem direta do potencial na superfície do titanato de bário dopado, o qual é cerâmica semicondutora. As medidas de EFM foram realizadas no modo não contato, mantendo a distância ponta-amostra de 75 nm constante, mas variando a voltagem bias aplicada à amostra de zero a 10 V. A distribuição do potencial na amostra mostrou mudanças em regiões próximas ao contorno de grão, exibindo largura de barreira constante de 145,2 nm.

  3. Tungsten Bronze Barium Neodymium Titanate (Ba(6-3n)Nd(8+2n)Ti(18)O(54)): An Intrinsic Nanostructured Material and Its Defect Distribution.

    Science.gov (United States)

    Azough, Feridoon; Cernik, Robert Joseph; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu; Bigatti, Marco; Ali, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub Dominik; Parker, Stephen Charles; Freer, Robert

    2016-04-04

    We investigated the structure of the tungsten bronze barium neodymium titanates Ba(6-3n)Nd(8+2n)Ti(18)O(54), which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba(6-3n)Nd(8+2n)Ti(18)O(54) (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba(6-3n)Nd(8+2n)Ti(18)O(54) "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity.

  4. A Piezoelectric Plethysmograph Sensor Based on a Pt Wire Implanted Lead Lanthanum Zirconate Titanate Bulk Ceramic

    Directory of Open Access Journals (Sweden)

    Ernesto Suaste-Gómez

    2010-07-01

    Full Text Available This work reports on the development of a Lead Lanthanum Zirconate Titanate (PLZT bulk ferroelectric poled ceramic structure as a Piezoelectric Plethysmograph (PZPG sensor. The ceramic was implanted during its fabrication with a platinum (Pt wire which works as an internal electrode. The ceramic was then submitted to an experimental setup in order to validate and determine the Pt-wire mechanical effects. This PZPG sensor was also mounted on a finger splint in order to measure the blood flow that results from the pulsations of blood occurring with each heartbeat. Fingertip pulses were recorded jointly with an ECG signal from a 25 year old male to compare the time shift; the PZPG sensor guarantees the electrical isolation of the patient. The proposed PZPG has several advantages: it can be adjusted for fingertip measurements, but it can easily be extended by means of spare bands, therefore making possible PZPG measurements from different body locations, e.g., forehead, forearm, knee, neck, etc.

  5. Mn and Sm doped lead titanate ceramic fibers and fiber/epoxy 13 composites

    Science.gov (United States)

    Li, Kun; Pang, Geoffrey; Wa Chan, Helen Lai; Choy, Chung Loong; Li, Jin-hua

    2004-05-01

    Manganese and samarium doped lead titanate [Pb0.85Sm0.10(Ti0.98Mn0.02)O3, PSmT] fibers were prepared by sol-gel method. The micrographs obtained using scanning electron microscope show that PSmT ceramic fibers are round and dense. The diameter of the fibers was in the range of 30-35 μm. The crystalline grains size is ˜2.5 μm. The micrographs obtained using transmission electron microscope also unveiled the layer-by-layer 90° domains in the grains. X-ray diffraction patterns of the fibers show that PSmT ceramics have a pure perovskite structure. The c/a ratio of the unit cell was 1.04. The PSmT fiber/epoxy 1-3 composites were fabricated by filling the ceramic fiber bundle with epoxy. The dielectric permittivity ɛ, electromechanical coefficient kt, and the piezoelectric constant d33 of PSmT fiber/epoxy 1-3 composites with 68% fiber loading were 118, 0.51, and 48 pC/N, respectively. The hysteresis loop of the composites was measured by the Sawyer-Tower method. It was also found that the composites could withstand an electric field of 15 kV/mm at room temperature.

  6. 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.

  7. 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.

  8. Preparation of Barium Titanate Films and Its Structural Characterization and Adhesive Strength%钛酸钡膜的制备、结构及结合强度

    Institute of Scientific and Technical Information of China (English)

    王新华; 赵晓云

    2011-01-01

    The barium titanate films have been grown on the surface of the titanium alloy by the micro-arc oxidation. The effect of the electrolyte composition, oxidation time, and micro-arc voltage on the structure and morphology of the films were discussed,and the adhesive strength of the BaTiO3 films was evaluated. The results showed that with increasing the concentration of electrolyte composition and oxidation time the more barium titanate films were formed. The morphology of the BaTiO3 films was influenced by the concentration of the electrolyte composition and the voltage as well as the oxidation time. With the decreasing of the voltage, the adhesive strength of the film layer tended to increase. At the voltage of 80 V, the adhesive strength can reach 36. 4 MPa, which is much higher than that of the coatings by general plasma spraying technique.%采用微弧氧化在钛合金表面制备BaTiO3膜.讨论电解液组分、反应时间及电压对BaTiO3膜形态和相组成的影响,并评价BaTiO3膜的结合强度.结果表明,BaTiO3的生成量随电解液浓度和氧化时间的增大而增加;其表面形貌也受电解液浓度、电压和氧化时间的影响;电压降低,膜层的结合强度有增大的趋势.电压为80 V时,结合强度可达36.4 Mpa,优于一般等离子喷涂技术获得的膜层结合强度.

  9. Dielectric and piezoelectric properties of neodymium oxide doped lead zirconate titanate ceramics

    Indian Academy of Sciences (India)

    Janardan Singh; N C Soni; S L Srivastava

    2003-06-01

    The dielectric and electromechanical properties of lead zirconate titanate [Pb(Zr, Ti)O3] ceramic added with neodymium oxide have been systematically studied employing the vector impedance spectroscopic (VIS) technique. The specimens were prepared using the mixed oxide route by adding different mol% of Nd2O3 (0.1 to 7 mol%) in [Pb(Zr, Ti)O3] near morphotropic phase boundary. Piezoelectric equivalent circuit parameters , , $C_a$ in series and $C_b$ in parallel have been determined by simulating /Z/ and plots. Electromechanical coupling coefficients and strain constants for the radial modes show a peak at about 3 mol%, the dielectric constant peaks at about 1 mol% and voltage constants peak at about 0.75 mol% of Nd2O3.

  10. Fabrication of barium titanate nanoparticles/poly (methylmethacrylate composite films by a combination of deposition process and spin-coating technique

    Directory of Open Access Journals (Sweden)

    Yoshio Kobayashi

    2014-10-01

    Full Text Available The present work proposes a method for fabricating poly(methylmethacrylate (PMMA film containing barium titanate (BT nanoparticles (BT/PMMA film. BT particles with an average size of 77.6 ± 30.5 nm and a crystal size of 28.1 nm were synthesized by adding sodium hydroxide aqueous solution to titanium tetraisopropoxide/acetylacetone/i-propanol solution suspending barium hydroxide. A sodium glass plate, of which surface was modified with polyvinylpyrrolidone, was immersed into water suspending the BT particles, which resulted in deposition of the BT particles on the plate. A BT/PMMA film was fabricated by twice performance of a process composed of spin-coating of N-methyl-2-pyrrolidone (NMP dissolving PMMA on the plate, and then drying the coated plate in the atmosphere at room temperature. Spin-coating of a PMMA/NMP solution with a PMMA concentration of 150 g/L at a rotating speed of 5000 rpm provided fabrication of a BT/PMMA film with a BT volume fraction of 35.5%, a thickness of ca. 300 nm, and a transmittance of ca. 90% in the visible light region.

  11. 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)

  12. High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    F. H. Wee

    2012-01-01

    Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

  13. Mineral-Oxide-Doped Aluminum Titanate Ceramics with Improved Thermomechanical Properties

    Directory of Open Access Journals (Sweden)

    R. Papitha

    2013-01-01

    Full Text Available Investigations were carried out, on the effect of addition of kaolinite (2Al2O3·3SiO2·2H2O and talc (Mg3Si4O10(OH2 in terms of bulk density, XRD phases, microstructure, as well as thermal and mechanical properties of the aluminium titanate (AT ceramics. AT ceramics with additives have shown enhanced sinterability at 1550°C, achieving close to 99% of TD (theoretical density in comparison to 87% TD, exhibited with pure AT samples sintered at 1600°C, and found to be in agreement with the microstructural observations. XRD phase analysis of samples with maximum densities resulted in pure AT phase with a shift in unit cell parameters suggesting the formation of solid solutions. TG-DSC study indicated a clear shift in AT formation temperature with talc addition. Sintered specimens exhibited significant reduction in linear thermal expansion values by 63% (0.4210−6/C, (30–1000°C with talc addition. Thermal hysteresis of talc-doped AT specimens showed a substantial increase in hysteresis area corresponding to enhanced microcrack densities which in turn was responsible to maintain the low expansion values. Microstructural evaluation revealed a sizable decrease in crack lengths and 200% increase in flexural strength with talc addition. Results are encouraging providing a stable formulation with substantially enhanced thermomechanical properties.

  14. 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.

  15. Elastic, dielectric, and piezoelectric properties of ceramic lead zirconate titanate/α-Al2O3 composites

    Science.gov (United States)

    Rybyanets, A. N.; Konstantinov, G. M.; Naumenko, A. A.; Shvetsova, N. A.; Makar'ev, D. I.; Lugovaya, M. A.

    2015-03-01

    The technology of producing ceramic lead zirconate titanate/α-Al2O3 composites has been developed. Elements of piezoactive composites containing from 0 to 60 vol % α-Al2O3 have been prepared. The elastic, dielectric, and piezoelectric parameters of the synthesized ceramic composites have been measured, and their microstructure has been studied. It has been found that the concentration dependences of the elastic and piezoelectric properties exhibit anomalies. The obtained data have been interpreted based on the percolation theory and the concept of microstructural constructing polycrystalline composition materials.

  16. Effect of B-site isovalent doping on electrical and ferroelectric properties of lead free bismuth titanate ceramics

    Science.gov (United States)

    Subohi, Oroosa; Kumar, G. S.; Malik, M. M.; Kurchania, Rajnish

    2016-06-01

    In the present work, zirconium modified bismuth titanate ceramics have been studied as potential lead-free ferroelectric materials over a broad temperature range (RT - 800 °C). Polycrystalline samples of Bi4Ti3-xZrxO12 (x=0.2, 0.4, 0.6) (BZrT) with high electrical resistivity were prepared using the solution combustion technique. The effect of Zr doping on the crystalline structure, ferroelectric properties and electrical conduction characteristics of BZrT ceramics were explored. Addition of zirconium to bismuth titanate enhances its dielectric constant and reduces the loss factor as it introduces orthorhombic distortion in bismuth titanate lattice which is exhibited by the growth along (00_10) lattice plane. Activation energy due to relaxation is found to be greater than that due to conduction thus confirming that electrical conduction in these ceramics is not due to relaxation of dipoles. Remanent polarization of the doped samples increases as the Zirconium content increases.

  17. Solid state (47,49)Ti, (87)Sr and (137)Ba NMR characterisation of mixed barium/strontium titanate perovskites.

    Science.gov (United States)

    Gervais, Christel; Veautier, Delphine; Smith, Mark E; Babonneau, Florence; Belleville, Philippe; Sanchez, Clément

    2004-01-01

    Solid state (47,49)Ti, (137)Ba, (87)Sr NMR spectra have been recorded on BaxSrl-xTiO3 (0 strontium) in the coordination second sphere of the probed titanium site: substitution of strontium by barium induces the broadening of the peaks, due to quadrupolar effects, while the isotropic chemical shift increases. (137)Ba NMR spectra exhibit a distribution of the quadrupolar interaction, that could be tentatively quantified, CQ increasing with the amount of strontium. Preliminary results were also obtained on (87)Sr NMR showing behaviour comparable to (137)Ba NMR, i.e. a broadening of the peaks due to an increasing quadrupolar interaction with the amount of barium distorting the environment of the strontium sites.

  18. Review on Barium Titanate Based Composites with High Energy Storage Density%高储能密度钛酸钡基复合材料

    Institute of Scientific and Technical Information of China (English)

    王亚军; 武晓娟; 曾庆轩

    2012-01-01

    高介电常数介电材料在储能方面的特殊作用使其在电工、电子技术领域有着重要的应用.随着电子工业的发展,高储能密度介电材料受到越来越多的关注,出现了一些新型的高储能密度介电材料.高储能密度介电材料具有高的介电常数和击穿强度,其发展的关键是提高储能密度.本文对近年来高储能密度介电材料的研究发展进行了概述,主要讨论了通过对钛酸钡的改性(即掺杂改性、表面包覆改性和复合材料制备)来提高介电材料的储能密度.分析了钛酸钡/聚合物复合材料的制备方法及其介电性能的影响因素,其中,陶瓷填料和聚合物基体2相界面的相容性是复合材料介电性能的重要影响因素.同时,指出了解决BaTiO3粒子在聚合物基体中的分散问题、填料和聚合物基体的选择以及制备过程中工艺条件的控制都是研究兼具高介电强度和高介电常数复合材料的发展方向.%Dielectric materials with high dielectric constant are widely used because of their excellent properties in energy storage, and play an important role in the area of electrical and electronic technologies. With the development of electronic industry, high energy density dielectric materials attract more and more attentions, and various novel dielectric materials with high energy storage density were developed. Dielectric materials with high energy storage density have high dielectric constants and high breakdown strength. It is an important issue to improve the energy storage density of dielectric materials. This paper reviews the latest development of high energy storage density dielectric materials, and discusses the modification of barium titanate to improve the energy storage density. Three approaches are adopted to achieve high electric energy density, namely, doping modification, surface coating and composite materials preparation. The main discussion is focused on the preparation

  19. Effect of temperature on polarization reversal of strontium-doped lead zirconate titanate (PSZT) ceramics

    Indian Academy of Sciences (India)

    N Nwathore; C M Lonkar; D K Kharat

    2011-02-01

    The effect of temperature on polarization reversal of strontium-doped lead zirconate titanate ceramics was studied. The piezoelectric properties viz. dielectric constant and piezoelectric coupling coefficient, were used for polarization reversal characteristic. These properties and apparent coercive field weremeasured during polarization reversal at different temperatures. Results indicated that at higher temperature apparent coercive field decreased. Polarization reversal and further polarization reversal was quite asymmetric. After polarization reversal, dielectric constant was found to increase at all temperatures while piezoelectric coupling coefficient increased above the temperature of polarization. The trend shown by dielectric constant indicates that at 25°C, 1.5 kV/mm field can be applied safely to this material without much compromising the properties. D.c. field of 3.0 kV/mm and 100°C temperature can be predicted as poling parameters from their effect on kp. Apparent coercive field has shown non-linear relationship with temperature. It was of exponential decay type.

  20. Crystal structure and electrical properties of bismuth sodium titanate zirconate ceramics.

    Science.gov (United States)

    Rachakom, Ampika; Jaiban, Panupong; Jiansirisomboon, Sukanda; Watcharapasorn, Anucha

    2012-01-05

    Lead-free bismuth sodium titanate zirconate (Bi0.5Na0.5Ti1-xZrxO3 where x = 0.20, 0.35, 0.40, 0.45, 0.60, and 0.80 mole fraction) [BNTZ] ceramics were successfully prepared using the conventional mixed-oxide method. The samples were sintered for 2 h at temperatures lower than 1,000°C. The density of the BNTZ samples was at least 95% of the theoretical values. The scanning electron microscopy micrographs showed that small grains were embedded between large grains, causing a relatively wide grain size distribution. The density and grain size increased with increasing Zr concentration. A peak shift in X-ray diffraction patterns as well as the disappearance of several hkl reflections indicated some significant crystal-structure changes in these materials. Preliminary crystal-structure analysis indicated the existence of phase transition from a rhombohedral to an orthorhombic structure. The dielectric and ferroelectric properties were also found to correlate well with the observed phase transition.

  1. 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.

  2. 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.

  3. Dielectric properties of Ga{sub 2}O{sub 3}-doped barium iron niobate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sanjoom, Kachaporn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Sri Ayutthaya Road, Bangkok, 10400 (Thailand); Pengpat, Kamonpan; Eitssayeam, Sukum; Tunkasiri, Tawee [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Rujijanagul, Gobwute [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai, 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Sri Ayutthaya Road, Bangkok, 10400 (Thailand)

    2014-08-15

    Ga-doped BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} (Ba(Fe{sub 1-x}Ga{sub x}){sub 0.5}Nb{sub 0.5}O{sub 3}) ceramics were fabricated and their properties were investigated. All ceramics showed perovskite structure with cubic symmetry and the solubility of Ga in BFN ceramics had a limit at x = 0.2. Examination of the dielectric spectra indicated that all ceramic samples presented high dielectric constants that were frequency dependent. The x = 0.2 ceramic showed a very high dielectric constant (ε{sub r} > 240 000 at 1 kHz) while the x = 0.4 sample exhibited high thermal stability of dielectric constant with low loss tangent from room temperature (RT) to 100 C with ε{sub r} > 28 000 (at 1 kHz) when compared to other samples. By using a complex impedance analysis technique, bulk grain, grain boundary, and electrode response were found to affect the dielectric behavior that could be related to the Maxwell-Wagner polarization mechanism. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Influence of Core-Shell Grains on the Internal Stress State and Permittivity Response of Zirconia Modified Barium Titanate

    Science.gov (United States)

    1989-04-01

    by the Office of Naval research’m Metalurgy and Ceramics Program Department of the NavyU Production in whole or in art is permitted for* -o .,any...multilayer capacitor formulations based on BaTiO 3 can be chemically or physically modified to exhibit temperature-stable dielectric behavior (less than

  5. 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.

  6. 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.

  7. Deformation behavior of lead zirconate titanate ceramics under uniaxial compression measured by the digital image correlation method

    Science.gov (United States)

    Chen, Di; Carter, Emma; Kamlah, Marc

    2016-09-01

    The deformation behavior of lead zirconate titanate bulk ceramic specimen under uniaxial compression was monitored by the digital image correlation method and the homogeneity of the deformation was discussed. Combined with using a Sawyer-Tower circuit, the depolarization curve was also obtained. Because of the friction at both the top and bottom surfaces of the lead zirconate titanate ceramic specimen, the distribution of deformation under large uniaxial compressive stresses usually shows a barrel shape. By focusing on correspondingly selected regions of interest and calculating the values of strain components there, the barreling behavior was proved. This barreling behavior is due to elastic strains, in the first place, while the remnant strains are less affected by this phenomenon. All these findings are the experimental justifications for the selection of an aspect ratio of 3:1 for our specimens, where only the central cubic region of a specimen represents the desired purely uniaxial stress state. Only from this region, true uniaxial stress-strain results can be obtained to develop constitutive models.

  8. Electrical characteristics of bismuth titanate glass-ceramics containing SiO2 and Nd2O3

    Directory of Open Access Journals (Sweden)

    Stanislav S. Slavov

    2010-03-01

    Full Text Available Bismuth-titanate ceramics containing SiO2 and Nd2O3 as additives are synthesized at two different ways of cooling of the melts. The introduction of SiO2 and Nd2O3 leads to more complex crystallization with participation of several phases including Bi4Ti3O12. It is proved that the applied methods of synthesis are suitable for generation of different microstructures in the bulk doped bismuth titanate ceramics, which is promising basis for modification of their electrical properties. The increasing of SiO2 content improves the glass formation ability and addition of Nd2O3 stimulates the crystallization. The conductivity of selected samples is determined by impedance analyzer in the frequency range from 10 to 100 kHz and DC resistible bridge using two-terminal method. All investigated samples are dielectrics with conductivity 10-6–10-9 (Ω·cm-1.

  9. Enhanced proton conductivity of yttrium-doped barium zirconate with sinterability in protonic ceramic fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ka-Young; Seo, Yongho; Kim, Ki Buem [HMC & Green Energy Research Institute, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Song, Sun-Ju [Department of Materials Science and Engineering, Chonnam National University, Gwangju 550-749 (Korea, Republic of); Park, Byoungnam [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Park, Jun-Young, E-mail: jyoung@sejong.ac.kr [HMC & Green Energy Research Institute, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)

    2015-08-05

    Highlights: • Report effects of ceramic processing methods on the electrical conductivity of BZY. • Present effects of sintering aids on the conductivity and density of BZY. • CuO is the most effective sintering aid for the BZY. • Polymer gelation is the most effective method in terms of conductivity of BZY. • Grain boundary conductivity of the polymer gelation BZY is higher than others. - Abstract: In this study, we report the effects of various ceramic processing methods with different sintering aids on the relative density, crystallinity, microstructure, and electrical conductivity of proton conducting BaZr{sub 0.85}Y{sub 0.15}O{sub 3−δ} (BZY) pellets in details. First, the BZY ceramic pellets are fabricated by the solid-state reactive sintering by adding diverse sintering aids including CuO, NiO, ZnO, SnO, MgO, and Al{sub 2}O{sub 3}. Among these, CuO is found to be the most effective sintering aid in terms of the sintering temperature and total conductivity. However, transition metals as sintering aids have detrimental effects on the electrical conductivity of the BZY electrolytes. Second, the BZY electrolytes have been synthesized by four different methods: the solid-state, combustion, hydrothermal, and polymer gelation methods. The BZY pellets synthesized by the polymer gelation method exhibit dense microstructure with a high relative density of 95.3%. Moreover, the electrical conductivity of the BZY pellets synthesized by the polymer gelation method is higher than those prepared by the solid-state methods under the same test conditions: 1.28 × 10{sup −2} S cm{sup −1} (by the polymer gelation method) vs. 0.53 × 10{sup −2} S cm{sup −1} by the solid-state method at 600 °C in wet 5% H{sub 2} in Ar.

  10. Effect of Neodymium on Optical Bandgap and Microwave Dielectric Properties of Barium Zirconate Ceramic

    Science.gov (United States)

    Parida, Sabyasachi; Satapathy, A.; Sinha, E.; Bisen, Anurag; Rout, S. K.

    2015-03-01

    The ceramics with general formula Ba(1- x) Nd(2 x/3)ZrO3 ( x = 0.0,0.02, 0.04, 0.06, 0.08, and 0.1) were prepared by solid-state reaction. The phase formation of the powders was analyzed by means of X-ray diffraction (XRD), Fourier transform-Raman (FT-Raman), and Fourier transform infrared (FTIR) spectroscopy. XRD patterns revealed that all powders show a perovskite-type cubic structure with space group Pm-3 m. FT-Raman and FTIR spectra suggested the formation of higher degree of symmetry in the crystal. The optical bandgap was found to be decreasing while Urbach energy was found to be increasing with an increase of Nd3+ content. The surface morphology of sintered pellets was studied by scanning electron microscope. Microwave dielectric constant and quality factor were investigated by the TE01 δ mode dielectric resonator method. The microwave dielectric constant and temperature coefficient of resonant frequency decreases with increase in of Nd3+ content. The irregular nature of quality factor ( Q × f) was observed due to the extrinsic losses in materials. The dielectric resonator antenna (DRA) characteristics were investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high-frequency structure simulator software, respectively. The resonant frequency and bandwidth of DRAs were also investigated for the ceramics.

  11. In situ neutron diffraction studies of a commercial, soft lead zirconate titanate ceramic: response to electric fields and mechanical stress

    Science.gov (United States)

    Pramanick, Abhijit; Prewitt, Anderson D.; Cottrell, Michelle A.; Lee, Wayne; Studer, Andrew J.; An, Ke; Hubbard, Camden R.; Jones, Jacob L.

    2010-06-01

    Structural changes in commercial lead zirconate titanate (PZT) ceramics (EC-65) under the application of electric fields and mechanical stress were measured using neutron diffraction instruments at the Australian Nuclear Science and Technology Organisation (ANSTO) and the Oak Ridge National Laboratory (ORNL). The structural changes during electric-field application were measured on the WOMBAT beamline at ANSTO and include non-180° domain switching, lattice strains and field-induced phase transformations. Using time-resolved data acquisition capabilities, lattice strains were measured under cyclic electric fields at times as short as 30 μs. Structural changes including the (002) and (200) lattice strains and non-180° domain switching were measured during uniaxial mechanical compression on the NRSF2 instrument at ORNL. Contraction of the crystallographic polarization axis, (002), and reorientation of non-180° domains occur at lowest stresses, followed by (200) elastic strains at higher stresses.

  12. Density variation and piezoelectric properties of Ba(Ti1−Sn)O3 ceramics prepared from nanocrystalline powders

    Indian Academy of Sciences (India)

    A K Nath; Nirmali Medhi

    2012-10-01

    Nanocrystalline powders of tin-doped barium titanate with different concentrations of tin have been synthesized by a combination of solid state reaction and high-energy ball milling. The average particle size of the milled powders as determined from TEM analysis was about 5.96 nm. Analysis of all the milled powders using X-ray diffraction method showed single phase perovskite structure. The density variation of the ceramics with sintering temperature has been studied by sintering the samples at different temperatures. Density variation results show that 1350°C is the optimum sintering temperature for tin-doped barium titanate ceramics. SEM micrographs show high density and increasing trend of grain size with increasing content of Sn. The ferroelectricity decreases with increasing concentration of Sn. The electromechanical coupling coefficient also decreases with increasing Sn content corroborating decreasing trend of ferroelectricity. The bipolar strain curves show piezoelectric properties of the prepared ceramics.

  13. Optical amplification in disordered electrooptic Tm3+ and Ho3+ codoped lanthanum-modified lead zirconate titanate ceramics and study of spectroscopy and communication between cations

    Science.gov (United States)

    Zhao, Hua; Zhang, Kun; Xu, Long; Sun, Fankui; Chen, Xuesheng; Li, Kewen K.; Zhang, Jingwen

    2014-02-01

    Rare earth doped electro-optic (EO) ceramics of lanthanum-modified lead zirconate titanate (PLZT) are promising in building multifunctional optical devices, by taking advantage of both EO effect and optical activity. In this work, the combination of the measured spectra of absorption and photoluminescence, the fluorescent decay, the calculated Judd-Ofelt parameters, and measured single pass gain in Tm3+, Ho3+ codoped PLZT ceramics have marked them out as promising gain media in building electrically controllable lasers/optical amplifiers and other multifunctional devices. Optical energy storage was also observed in the optical amplification dynamics.

  14. 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.

  15. 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.

  16. 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.

  17. Fatigue properties and impedance analysis of potassium sodium niobate-strontium titanate transparent ceramics

    Science.gov (United States)

    Liu, Zhiyong; Fan, Huiqing; Lei, Shenhui; Wang, Ju; Tian, Hailin

    2016-10-01

    Highly transparent ferroelectric ceramics based on 0.9K0.5Na0.5NbO3-0.1SrTiO3 were prepared using a pressure-less solid-state sintering method without using hot isostatic pressing and spark plasma sintering. An independence electromechanical response of bipolar switching cycles ( S 33 only degraded 3.2 % up to 107 cycles) was presented in this transparent ceramics, which indicated an extremely stable property under electric field. From impedance spectroscopy and X-ray photoelectron spectroscopy analyses, it was concluded that such optical transparency and fatigue-resistant behaviors were mainly attributed to the lower density of oxygen vacancies in the ceramics.

  18. Fatigue properties and impedance analysis of potassium sodium niobate-strontium titanate transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhiyong; Fan, Huiqing; Lei, Shenhui; Wang, Ju; Tian, Hailin [Northwestern Polytechnical University, State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Xi' an (China)

    2016-10-15

    Highly transparent ferroelectric ceramics based on 0.9K{sub 0.5}Na{sub 0.5}NbO{sub 3}-0.1SrTiO{sub 3} were prepared using a pressure-less solid-state sintering method without using hot isostatic pressing and spark plasma sintering. An independence electromechanical response of bipolar switching cycles (S{sub 33} only degraded 3.2 % up to 10{sup 7} cycles) was presented in this transparent ceramics, which indicated an extremely stable property under electric field. From impedance spectroscopy and X-ray photoelectron spectroscopy analyses, it was concluded that such optical transparency and fatigue-resistant behaviors were mainly attributed to the lower density of oxygen vacancies in the ceramics. (orig.)

  19. Dielectric behaviour of (Ba0.77Ca0.23(Ti0.98Dy0.02O3 ceramics

    Directory of Open Access Journals (Sweden)

    Abdul Moquim

    2015-06-01

    Full Text Available In this study, BaTiO3 is modified with Ca2+ and in addition doped with Dy3+ at the B site lattice. The main idea is to search for new lead-free ferroelectric material and improve their properties. For this purpose, the barium calcium titanate (BCT as a host and the rare earth element Dy3+ as an activator were used to fabricate a multifunctional material. The obtained ceramics was found to be homogeneous, dense and a single phase material with no evidence of secondary phases. The dielectric study showed that TC increases with the addition of dopants and the obtained ceramics behaves like a relaxor ferroelectric. Some important structural parameters and dielectric properties of dysprosium modified barium (calcium titanate ceramics are presented.

  20. 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.

  1. Effect of Fe and Fe-Ba substitution on the piezoelectric and dielectric properties of lead zirconate titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sangawar, S.R., E-mail: sudhirsangawar85@gmail.com [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India); Praveenkumar, B.; Kumar, H.H.; Kharat, D.K. [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India)

    2011-02-25

    Polycrystalline samples of Fe and Fe-Ba doped lead zirconate titanate (PZT) ceramics near the morphotrophic phase boundary have been synthesized by a solid-state reaction technique. Preliminary X-ray analysis of the compound confirms that there is no change in the crystal structure of PZT on co-doping with Fe and Ba. The maximum mechanical quality factor Q{sub m} was found to be 1000 for Fe doped material and 880 for Fe-Ba doped material. The electromechanical coupling factor for Fe and Fe-Ba doped samples were 0.535 and 0.495 respectively. The corresponding values for the piezoelectric charge constant d{sub 33} were 135 and 250 pC/N respectively. These results are discussed in terms of position occupied by dopants in to the lattice and their corresponding microstructures. These Fe-Ba doped PZT materials could be likely candidates for high power ultrasonic and underwater SONAR transducer systems.

  2. Preparation and characterization of lead zirconate titanate ceramic fibers with alkoxide-based sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Mai Manfang; Lin Cheng; Xiong Zhaoxian; Xue Hao; Chen Lifu [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)], E-mail: zxxiong@xmu.edu.cn

    2009-03-01

    Lead zirconate titanate (PZT) fibers with diameters from 10{mu}m to 40{mu}m were prepared via a sol-gel route. Several kinds of chemicals were used, including lead acetate trihydrate, zirconium n-butoxide and titanium n-butoxide, in addition to butanol as a solvent. As a water source for hydrolysis reaction, Pb(CH{sub 3}COO){sub 2}{center_dot}3H{sub 2}O was directly used without further adding of water or catalyst conventionally. Acetylacetonate and acetate were added as stabilization agents to obtain stable sols for fiber drawing. The gel-to-ceramic conversion was characterized with thermal analysis, infrared spectroscopy and X-ray diffraction. A pure perovskite phase was obtained after heat treatment at 650 deg. C for 1h. By using scanning electron microscope (SEM), it was observed that a lower rate of heat treatment resulted in a denser microstructure of the fibers. The relative permittivity and the P-E hysteresis loop of the crystalline PZT fibers were also measured and discussed in the paper.

  3. Preparation and characterization of lead zirconate titanate ceramic fibers with alkoxide-based sol-gel route

    Science.gov (United States)

    Mai, Manfang; Lin, Cheng; Xiong, Zhaoxian; Xue, Hao; Chen, Lifu

    2009-03-01

    Lead zirconate titanate (PZT) fibers with diameters from 10μm to 40μm were prepared via a sol-gel route. Several kinds of chemicals were used, including lead acetate trihydrate, zirconium n-butoxide and titanium n-butoxide, in addition to butanol as a solvent. As a water source for hydrolysis reaction, Pb(CH3COO)2·3H2O was directly used without further adding of water or catalyst conventionally. Acetylacetonate and acetate were added as stabilization agents to obtain stable sols for fiber drawing. The gel-to-ceramic conversion was characterized with thermal analysis, infrared spectroscopy and X-ray diffraction. A pure perovskite phase was obtained after heat treatment at 650°C for 1h. By using scanning electron microscope (SEM), it was observed that a lower rate of heat treatment resulted in a denser microstructure of the fibers. The relative permittivity and the P-E hysteresis loop of the crystalline PZT fibers were also measured and discussed in the paper.

  4. 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.

  5. Pressure slip casting and cold isostatic pressing of aluminum titanate green ceramics: A comparative evaluation

    Directory of Open Access Journals (Sweden)

    Ramanathan Papitha

    2013-12-01

    Full Text Available Aluminum titanate (Al2TiO5 green bodies were prepared from mixture of titania and alumina powders with different particle sizes by conventional slip casting (CSC, pressure slip casting (PSC and cold isostatic pressing (CIP. Precursor-powder mixtures were evaluated with respect to the powder properties, flow behaviours and shaping parameters. Green densities were measured and correlated with the fractographs. A substantial increase in green densities up to 60 %TD (theoretical density of 4.02 g/cm3, calculated based on rule of mixtures is observed with the application of 2–3 MPa pressure with PSC. While particle size distribution and solid loading are the most influential parameters in the case of CSC, with PSC pressure also plays a key role in achieving the higher green densities. Being a dry process, high pressure of > 100 MPa for CIP is essential to achieve densities in the range of 60–65 %TD. Slip pressurization under PSC conditions facilitate the rearrangement of particles through rolling, twisting and interlocking unlike CIP processing where pressure is needed to overcome the inter-particle friction.

  6. Structural and ferroelectrical properties of bismuth titanate ceramic powders prepared by mechanically assisted synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2007-01-01

    Full Text Available Nanosized bismuth titanate, Bi4Ti3O12, was prepared via a high-energy ball milling process through mechanically assisted synthesis directly from the oxide mixture of Bi2O3 and TiO2. The Bi4Ti3O12 phase started to form after 1 h of milling. With increasing the milling time from 3 to 12 h, the particle size of formed Bi4Ti3O12 did not reduce significantly. The grain size was less than 16 nm and showed a strong tendency to agglomeration. The nucleation and phase formation of Bi4Ti3O12, crystal structure, microstructure, powder grain size and specific surface area were followed by XRD, Rietveld refinement analysis, SEM and the BET specific surface area measurements. Raman spectroscopy was used to explain the structural properties of Bi4Ti3O12 powder, prepared by mechanically assisted synthesis. Reduction in grain size with the increase of milling time was also noted (change in the position and relative intensity, which indicated changes in the structure, caused by nanodimension grains. The sample milled for 12 h and subsequently sintered at 1000°C for 24 h exhibited a hysteresis loop, confirming that the synthesized material possesses ferroelectric properties. .

  7. Photovoltaic and photostrictive effects in lanthanum-modified lead zirconate titanate ceramics

    Science.gov (United States)

    Poosanaas, Patcharin

    Photostriction is the light induced strain in a material, arising from the combination of photovoltaic and converse-piezoelectric effects. The possibility of directly producing strain by light illumination, without any electrical lead wire connection, makes the photostrictive materials very attractive for potential usage in future generation wireless remote controlled micro-actuator and micro-sensor. However, for the fabrication of these devices, materials exhibiting higher photovoltaic effect and higher response speed must be developed. This research was aimed towards investigating the mechanism of photovoltaic effect, developing photostrictive materials with enhanced performance, and exploring the limits of the photostriction. A new model based on the optical nonlinearity in ferroelectrics having noncentric symmetry has been proposed to explain the mechanism of photovoltaic effect. This model provides a better understanding of photostrictive phenomenon and agrees well with the experimental measurements carried out on PLZT ceramics. Among the various processing routes attempted, coprecipitation route was found to be most suitable for the fabrication of PLZT ceramics. High purity homogeneous powders with stoichiometric compositions obtained from this method yielded compacts with high density, fine grain size and uniformly distributed dopants. These desirable properties resulted in enhancement of photostrictive response. Photovoltaic and photoinduced strain were found to increase with decreasing grain size and increasing relative density. The composition, especially near the morphotropic phase boundary (MPB) of PLZT ceramics, was optimized for photovoltaic characteristics. The maximum photocurrent was observed in tetragonal phase 4/48/52 PLZT, while the maximum photovoltage was observed in 5/54/46 PLZT, which is around the MPB of the PLZT phase diagram. The photostriction was found to be strongly influenced by the surface characteristics (namely, sample thickness

  8. Influence of crystallization on the spectral features of nano-sized ferroelectric barium strontium titanate (Ba{sub 0.7}Sr{sub 0.3}Tio{sub 3}) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bobby Singh, S. [Department of Physics, Manipur University, Imphal 795003, Manipur (India)], E-mail: bsoram@rediffmail.com; Sharma, H.B.; Sarma, H.N.K.; Phanjoubam, Sumitra [Department of Physics, Manipur University, Imphal 795003, Manipur (India)

    2008-08-01

    Ferroelectric barium strontium titanate (Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3})(BST) thin films have been prepared from barium 2-ethylhexanoate [Ba[CH{sub 3}(CH{sub 2}){sub 3}CH(C{sub 2}H{sub 5})CO{sub 2}]{sub 2}]{sub ,} strontium 2-ethylhexanoate [Sr[CH{sub 3}(CH{sub 2}){sub 3}CH(C{sub 2}H{sub 5})CO{sub 2}]{sub 2}] and titanium(IV) isopropoxide [TiOCH(CH{sub 3}){sub 2}]{sub 4} precursors using a modified sol-gel technique. The precursor except [TiOCH(CH{sub 3}){sub 2}]{sub 4} were synthesized in the laboratory. Transparent and crack-free films were fabricated on pre-cleaned quartz substrates by spin coating. The structural and optical properties of films annealed at different temperatures have been investigated. The as-fired films were found to be amorphous that crystallized to the tetragonal phase after annealing at 550 deg. C for 1 h in air. The lattice constants 'a' and 'c' were found to be 3.974 A and 3.990 A, respectively. The grain sizes of the films annealed at 450, 500 and 550 deg. C were found to be 30.8, 36.0 and 39.8 nm respectively. The amorphous film showed very high transparency ({approx}95%), which decreases slightly after crystallization ({approx}90%). The band gap and refractive index of the amorphous and crystalline films were estimated. The optical dispersion data are also analyzed in the light of the single oscillator model and are discussed.

  9. New method for measuring high field electrostrictive response of barium titanate/polyurethane elastomer%一种测量钛酸钡/聚氨酯材料电致伸缩性能的新方法

    Institute of Scientific and Technical Information of China (English)

    陈凡秀; 丛羽奇; 林保平; 李建清; 何小元

    2006-01-01

    A new method for measuring the characteristic of electrostriction by a digital speckle correlation method (DSCM) is presented. The in-plane displacement is obtained by using the DSCM, and the out-plane displacement is obtained by the geometrical relation of the triangle theory. In this application, high field electrostrictive strains of barium titanate/polyurethane elastomer composite materials are measured. The electrostrictive strain is evaluated when the application of an electric field is repeated, and then the electrostrictive coefficient of the sample is obtained. To improve the measuring accuracy, the bilinear interpolation of gray value is used to obtain the sub-pixel gray value. The results are compared with those obtained from the surface fitting algorithm. The experimental results demonstrate that the electrostrictive response of polyurethane increases with the introduction of barium titanate into polyurethane. And by using the DSCM, the measurement of the characteristic of electrostriction can be done quickly and accurately. The DSCM provides an effective tool for the evaluation of electrostrictive response.%提出利用数字散斑相关方法测量材料的电致伸缩性能的新方法.通过数字散斑相关方法得到面内位移,从而由几何三角关系得到离面位移,实现电致伸缩应变的测量.采用该方法对高电场作用下钛酸钡/聚氨酯复合高分子材料的电致伸缩性能进行了测量.在高电场作用下,对重复加电放电过程进行分析,得到电致伸缩应变,从而获取材料的电致伸缩系数.实验中采用双线性插值方法获取亚象素灰度值,以提高测量精度,并将结果与曲面拟合算法的计算结果进行了比较.结果表明:钛酸钡的加入提高了聚氨酯材料的电致伸缩性能;数字散斑相关方法可以有效地实现材料的电致伸缩系数的测量.该方法为电致伸缩性能的研究提供了一种有效的工具.

  10. Microstructure and relaxor ferroelectric properties of Bi{sub 2}O{sub 3}-doped strontium barium niobate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jinglei, E-mail: lilei19871003@yahoo.com.cn; Pu, Yongping; Wang, Zhuo; Dong, Zijing; Dai, Jie

    2013-11-01

    Highlights: • Bi{sub 2}O{sub 3} addition could promote the grain growth in Sr{sub 0.4}Ba{sub 0.6}Nb{sub 2}O{sub 6} ceramics. • Doping Bi{sub 2}O{sub 3} could improve the dielectric constant and lower the dielectric loss. • The dielectric characteristics of doping Bi{sub 2}O{sub 3} samples showed relaxation behavior. • The P–E hysteresis loops for doping Bi{sub 2}O{sub 3} ceramics became slimmer. -- Abstract: (1 − x) Sr{sub 0.4}Ba{sub 0.6}Nb{sub 2}O{sub 6}–xBi{sub 2}O{sub 3} (0.00 ≤ x ≤ 0.20) ceramics were prepared by conventional solid-state reaction method. The microstructure, dielectric properties and P–E hysteresis loops of ceramics were investigated via X-ray diffraction, scanning electron microscope (SEM), Agilent E4980A and modified Sawyer–Tower circuit, respectively. XRD results showed the obtained ceramics were of tungsten bronze structure, and second phase Sr{sub 0.4}Ba{sub 0.6}Bi{sub 2}Nb{sub 2}O{sub 9} was detected at high doping concentration. SEM results showed suitable Bi{sub 2}O{sub 3} addition could reduce the sintering temperature and assist the grain growth. The dielectric characteristics exhibited diffuse phase transition phenomena, which were verified by linear fitting of the modified Curie–Weiss law. Besides, the relaxor ferroelectric properties of ceramics followed the Vogel–Fulcher relationship well. The P–E hysteresis loops became slimmer with increasing the Bi{sub 2}O{sub 3} addition, leading to a gradually decrease in both remnant polarization (P{sub r}) and coercive field (E{sub c})

  11. 注凝成型制备莫来石-钛酸铝复相陶瓷%PREPARATION OF MULLITE-ALUMINIUM TITANATE CERAMIC COMPOSITES VIA GELCASTING

    Institute of Scientific and Technical Information of China (English)

    陆洪彬; 陈建华; 冯春霞; 焦宝祥; 孟祥康

    2009-01-01

    The mullite-aluminium titanate (MAT) ceramic composites were prepared via the gelcasting or dry pressing processes us- ing industrial mullite and aluminium titanate (Al2TiO5) powders with different mass ratios, that titanate was synthesized by doping the bi-component additive of 10% (in mole, the same below) MgO and 15% SiO2 relative to Al2O3. Effects of the bi-component additive on the phase composition and thermal stabilization of aluminium titanate powder were analyzed by X-ray diffraction and the micro- structures of MAT ceramic composites were characterized by scanning electron microscopy. The effects of aluminium titanate content on the bending strength and average thermal expansion coefficient (room temperature-1000 ℃) of the MAT ceramic composites pre- pared by dry pressing or gelcasting shaping processes were also investigated. The results show that the bi-component additive of MgO and SiO2 can promote the formation of Al2TiO5 and enhance its thermal stabilization. The MAT ceramic composites prepared by gel- casting process obtain more homogenous structure and higher bending strength than that prepared by dry pressing process. The MAT ceramic composite prepared by gelcasting process and containing 10% (mass fraction) Al2TiO5 has the maximum bending strength of 110.05 MPa.%引入10%(摩尔分数,相对于A12O3,下同)MgO和15%SiO2双组分添加剂合成了钛酸铝粉体.采用不同质量比的钛酸铝粉体和工业莫来石,用干压和注凝成型工艺制备了莫来石-钛酸铝(mullite-aluminium titanate,MAT)复相陶瓷.用X射线衍射分析了双组分添加剂对钛酸铝相组成和热稳定性的影响.通过扫描电镜表征了MAT复相陶瓷的微结构.研究了钛酸铝含量对采用于压、注凝2种成型工艺制备的MAT复相陶瓷的弯曲强度和平均热膨胀系数(室温~1 000℃)的影响.结果表明:MgO和SiO2双组分添加剂促进了钛酸铝的形成,增强了钛酸铝的热稳定性.通过注凝成型制备

  12. A new type of microphone using flexoelectric barium strontium titnate

    Science.gov (United States)

    Kwon, Seol ryung; Huang, Wenbin; Zhang, Shujun; Yuan, Fuh-Gwo; Jiang, Xiaoning

    2014-03-01

    A flexoelectric bridge-structured microphone using bulk barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was investigated in this study. The flexoelectric microphone was installed in an anechoic box and exposed to the sound pressure emitted from a loud speaker. Charge sensitivity of the flexoelectric microphone was measured and calibrated using a reference microphone. The 1.5 mm×768 μm×50 μm micro-machined bridge-structured flexoelectric microphone has a sensitivity of 0.92 pC/Pa, while its resonance frequency was calculated to be 98.67 kHz. The analytical and experimental results show that the flexoelectric microphone has both high sensitivity and broad bandwidth, indicating that flexoelectric microphones are potential candidates for many applications.

  13. Effect of Processing on Synthesis and Dielectric Behavior of Bismuth Sodium Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    Vijayeta Pal

    2013-01-01

    Full Text Available An effort has been made to synthesize polycrystalline (Bi1−xLax0.5Na0.5TiO3 (abbreviated as BLNT system with compositions x = 0, 0.02, and 0.04 by novel semiwet technique. Preparation of A-site oxides of BLNT for composition x = 0 was optimized using two precursor solutions such as ethylene glycol and citric acid. The XRD patterns revealed that the sample prepared by ethylene glycol precursor solution has single phase perovskite structure with a rhombohedral symmetry at RT as compared to the sample prepared by citric acid. Ethylene glycol precursor has been found to play a significant role in the crystallization, phase transitions, and electrical properties. The studies on structure, phase transitions, and dielectric properties for all the samples have been carried out over the temperature range from RT to 450°C at 100 kHz frequency. It has been observed that two phase transitions (i ferroelectric to antiferroelectric and (ii antiferroelectric to paraelectric occur in all the samples. All samples exhibit a modified Curie-Weiss law above Tc. A linear fitting of the modified Curie-Weiss law to the experimental data shows diffuse-type transition. The dielectric as well as ferroelectric properties of BLNT ceramics have been found to be improved with the substitution of La elements.

  14. Large Electrocaloric Effect in Relaxor Ferroelectric and Antiferroelectric Lanthanum Doped Lead Zirconate Titanate Ceramics

    Science.gov (United States)

    Lu, Biao; Li, Peilian; Tang, Zhenhua; Yao, Yingbang; Gao, Xingsen; Kleemann, Wolfgang; Lu, Sheng-Guo

    2017-01-01

    Both relaxor ferroelectric and antiferroelectric materials can individually demonstrate large electrocaloric effects (ECE). However, in order to further enhance the ECE it is crucial to find a material system, which can exhibit simultaneously both relaxor ferroelectric and antiferroelectric properties, or easily convert from one into another in terms of the compositional tailoring. Here we report on a system, in which the structure can readily change from antiferroelectric into relaxor ferroelectric and vice versa. To this end relaxor ferroelectric Pb0.89La0.11(Zr0.7Ti0.3)0.9725O3 and antiferroelectric Pb0.93La0.07(Zr0.82Ti0.18)0.9825O3 ceramics were designed near the antiferroelectric-ferroelectric phase boundary line in the La2O3-PbZrO3-PbTiO3 phase diagram. Conventional solid state reaction processing was used to prepare the two compositions. The ECE properties were deduced from Maxwell relations and Landau-Ginzburg-Devonshire (LGD) phenomenological theory, respectively, and also directly controlled by a computer and measured by thermometry. Large electrocaloric efficiencies were obtained and comparable with the results calculated via the phenomenological theory. Results show great potential in achieving large cooling power as refrigerants. PMID:28345655

  15. 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.

  16. Tritium breeding mock-up experiments containing lithium titanate ceramic pebbles and lead irradiated with DT neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Jakhar, Shrichand; Abhangi, M.; Tiwari, S. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Makwana, R. [Department of Physics, MS University, Vadodara (India); Chaudhari, V.; Swami, H.L.; Danani, C.; Rao, C.V.S.; Basu, T.K. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Mandal, D.; Bhade, Sonali; Kolekar, R.V.; Reddy, P.J. [Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Bhattacharyay, R.; Chaudhuri, P. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

    2015-06-15

    Highlights: • Breeding benchmark experiment on LLCB TBM in ITER was performed. • Nuclear responses measured are TPR and reaction rate of {sup 115}In(n, n′){sup 115m}In reaction. • Measured responses are compared with calculations by MCNP and FENDL 2.1 library. • TPR measurements agree with calculations in the estimated error bar. • Measured {sup 115}In(n, n′){sup 115m}In reaction rates are underestimated by the calculations. - Abstract: Experiments were conducted with breeding blanket mock-up consisting of two layers of breeder material lithium titanate pebbles and three layers of pure lead as neutron multiplier. The radial dimensions of breeder, neutron multiplier and structural material layers are similar to the current design of the Indian Lead–Lithium cooled Ceramic Breeder (LLCB) blanket. The mock-up assembly was irradiated with 14 MeV neutrons from DT neutron generator. The local tritium production rates (TPR) from {sup 6}Li and {sup 7}Li in breeder layers were measured with the help of two different compositions of Li isotopes (60.69% {sup 6}Li and 7.54% {sup 6}Li) in Li{sub 2}CO{sub 3}. Tritium production in the multiplication layers were also measured with above mentioned two types of pellets to compare the experimental tritium production with calculations. TPR from {sup 6}Li at one location in the breeder layer was also measured by direct online measurement of tritons from {sup 6}Li(n, t){sup 4}He reaction using silicon surface barrier detector and {sup 6}Li to triton converter. Additional verification of neutron spectra (E{sub n} > 0.35 MeV) in the mock-up zones were obtained by measuring {sup 115}In(n, n′){sup 115m}In reaction rate and comparing it with calculated values in all five layers of mock-up. All the measured nuclear responses were compared with transport calculations using code MCNP with FENDL2.1 and FENDL3.0 cross-section libraries. The average C/E ratio for tritium production in enriched Li{sub 2}CO{sub 3} pellets was 1

  17. Moisture in multilayer ceramic capacitors

    Science.gov (United States)

    Donahoe, Daniel Noel

    When both precious metal electrode and base metal electrode (BME) capacitors were subjected to autoclave (120°C/100% RH) testing, it was found that the precious metal capacitors aged according to a well known aging mechanism (less than 3% from their starting values), but the BME capacitors degraded to below the -30% criterion at 500 hours of exposure. The reasons for this new failure mechanism are complex, and there were two theories that were hypothesized. The first was that there could be oxidation or corrosion of the nickel plates. The other hypothesis was that the loss of capacitance was due to molecular changes in the barium titanate. This thesis presents the evaluation of these hypotheses and the physics of the degradation mechanism. It is concluded by proof by elimination that there are molecular changes in the barium titanate. Furthermore, the continuous reduction in capacitor size makes the newer base metal electrode capacitors more vulnerable to moisture degradation than the older generation precious metal capacitors. In addition, standard humidity life testing, such as JESD-22 THB and HAST, will likely not uncover this problem. Therefore, poor reliability due to degradation of base metal electrode multilayer ceramic capacitors may catch manufacturers and consumers by surprise.

  18. Modeling the dielectric response of lanthanum modified lead zirconate titanate ferroelectric ceramics-an approach to the phase transitions in relaxor ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    GarcIa-ZaldIvar, O; Pelaiz-Barranco, A; Calderon-Pinar, F; Fundora-Cruz, A [Facultad de Fisica-Instituto de Ciencia y TecnologIa de Materiales, Universidad de La Habana, San Lazaro y L, Vedado 10400, La Habana (Cuba); Guerra, J D S [Departamento de Fisica e Quimica, Universidade Estadual Paulista, 15385-000, Ilha Solteira-SP (Brazil); Hall, D A [School of Materials, University of Manchester, Manchester, M1 7HS (United Kingdom); Mendoza, M E [Instituto de Fisica, Universidad Autonoma de Puebla, AP J-48, 72570, Puebla (Mexico)], E-mail: santos@dfg.feis.unesp.br

    2008-11-05

    The relaxor behavior of lanthanum modified lead zirconate titanate (PLZT) ferroelectric ceramics, for a La/Zr/Ti ratio of x/60/40, has been analyzed. An approximation to the dynamical behavior of the polar nano-regions (PNRs) has been discussed, taking into account a relaxation model, which considers a distribution function for the relaxation times. A good agreement between theoretical and experimental results was obtained. The behaviors of the mean relaxation time and its standard deviation with temperature were discussed, considering the correlation between the polar nano-regions and the freezing temperature. The temperature dependence of the polarization showed an anomalous behavior around a temperature, which was associated with the freezing temperature, according to the proposed model in the present work.

  19. Electrical Properties Of Indium And Yttrium-Doped Barium Cerate-Based Compounds For Use As Ceramic Fuel Cell Electrolytes

    Directory of Open Access Journals (Sweden)

    Gawel R.

    2015-06-01

    Full Text Available The aim of this work is to compare the electrical properties of BaCe0.85Y0.15O3−δ (BCY15, BaCe0.70In0.30O3−δ (BCI30 and a composite material consisting of 30%vol. BCY15 and 70%vol. Ce0.85Y0.15O2−δ (YDC15. BCY15 and YDC15 were synthesized by co-precipitation, whereas BCI30 was obtained using the solid-state reaction method. Pellets were initially formed from powders at 5 MPa, after which they were isostatically pressed at 250 MPa and sintered at 1500°C. Electrochemical impedance spectroscopy (EIS was used to determine the electrical properties of the samples in both air (pO2 = 0.021 MPa and Ar-5%H2 atmospheres. In the temperature range 200-400°C in air atmosphere the highest conductivity values were determined for BCY15 (5,22·10−5 − 2.74·10−3 S/cm. On the other hand, the electrical conductivity values obtained for Y70B30 in both atmospheres between 200 and 550°C are in the order of magnitude of 10−7 − 10−3 S/cm. Consequently, it can be concluded that the compounds exhibit significant H+ and O2− electrical conductivity at temperatures above 500°C, which indicates the possibility for their potential use as ceramic fuel cell electrolytes.

  20. 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.

  1. 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.

  2. One-Step Synthesis of Hollow Titanate (Sr/Ba) Ceramic Fibers for Detoxification of Nerve Agents

    OpenAIRE

    2012-01-01

    Poly(vinyl pyrrolidone)(PVP)/(strontium/barium acetate)/titanium isopropoxide composite fibers were prepared by electrospinning technique via sol-gel process. Diameters of fibers prepared by calcinations of PVP composite fibers were 80–140 nm (solid) and 1.2-2.2 μm (hollow fibers prepared by core-shell method). These fibers were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) analytical techniques. XRD results showed ...

  3. 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.

  4. 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

  5. Influence of nanogold additives on phase formation, microstructure and dielectric properties of perovskite BaTiO3 ceramics

    Science.gov (United States)

    Nonkumwong, Jeeranan; Ananta, Supon; Srisombat, Laongnuan

    2015-06-01

    The formation of perovskite phase, microstructure and dielectric properties of nanogold-modified barium titanate (BaTiO3) ceramics was examined as a function of gold nanoparticle contents by employing a combination of X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, Archimedes principle and dielectric measurement techniques. These ceramics were fabricated from a simple mixed-oxide method. The amount of gold nanoparticles was found to be one of the key factors controlling densification, grain growth and dielectric response in BaTiO3 ceramics. It was found that under suitable amount of nanogold addition (4 mol%), highly dense perovskite BaTiO3 ceramics with homogeneous microstructures of refined grains (~0.5-3.1 μm) and excellence dielectric properties can be produced.

  6. One-Step Synthesis of Hollow Titanate (Sr/Ba Ceramic Fibers for Detoxification of Nerve Agents

    Directory of Open Access Journals (Sweden)

    Satya R. Agarwal

    2012-01-01

    Full Text Available Poly(vinyl pyrrolidone(PVP/(strontium/barium acetate/titanium isopropoxide composite fibers were prepared by electrospinning technique via sol-gel process. Diameters of fibers prepared by calcinations of PVP composite fibers were 80–140 nm (solid and 1.2-2.2 μm (hollow fibers prepared by core-shell method. These fibers were characterized using scanning electron microscope (SEM, X-ray diffraction (XRD, and transmission electron microscope (TEM analytical techniques. XRD results showed better crystalline nature of the materials when calcined at higher temperatures. SEM and TEM results clearly showed the formation of hollow submicrometer tubes. The surface area of the samples determined by BET analysis indicated that hollow fibers have ~20% higher surface area than solid fibers. The UV studies indicate better detoxification properties of the hollow fibers compared to solid fibers.

  7. Oxygen diffusion in single crystal barium titanate.

    Science.gov (United States)

    Kessel, Markus; De Souza, Roger A; Martin, Manfred

    2015-05-21

    Oxygen diffusion in cubic, nominally undoped, (100) oriented BaTiO3 single crystals has been studied by means of (18)O2/(16)O2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Experiments were carried out as a function of temperature 973 coefficient ks*, the space-charge potential Φ0 and the bulk diffusion coefficient D*(∞). Analysis of the temperature and oxygen activity dependencies of D*(∞) and Φ0 yields a consistent picture of both the bulk and the interfacial defect chemistry of BaTiO3. Values of the oxygen vacancy diffusion coefficient DV extracted from measured D*(∞) data are compared with literature data; consequently a global expression for the vacancy diffusivity in BaTiO3 for the temperature range 466 < T/K < 1273 is obtained, with an activation enthalpy of vacancy migration, ΔHmig,V = (0.70 ± 0.04) eV.

  8. 钛酸钾晶须耐碱多孔陶瓷的制备及表征%Preparation and Characterization of Alkaline Resistant Porous Ceramics from Potassium Titanate Whiskers

    Institute of Scientific and Technical Information of China (English)

    周亚新; 刘畅; 何明; 杨祝红; 冯新; 陆小华

    2007-01-01

    The preparation and characterization of alkaline resistant porous ceramics from potassium titanate whiskers are studied. K2Ti4O9 whiskers in the whisker preforms (mixtures of K2Ti6O13 and K2Ti4O9) were completely converted to K2Ti6O13 at 960℃. The alkaline resistance as well as the change in bending strength, porosity and permeability of the ceramics was investigated by altering the composition of the preforms in which the content of K2Ti6O13 whiskers was higher than 50% (molar fraction). The alkaline resistance of the porous K2Ti6O13 ceramics is found much higher than that of Al2O3 in caustic NaOH solutions, and further study indicates that the K2Ti6O13ceramics can be stably used in solutions of pH>2.0. The bending strength increases initially with the content of the raw K2Ti6O13 in the preforms up to 66% (molar fraction) and then decreases, contrary to the behaviors of porosity and permeability. The values of bending strength, porosity and permeability of the ceramics prepared from the precomparable to those of the porous Al2O3 ceramics.

  9. RESEARCH ON PREPARATION AND MICROSTRUCTURE OF BARIUM TITANATE BASED PTC CERAMICS%钛酸钡PTC陶瓷的制备及显微分析

    Institute of Scientific and Technical Information of China (English)

    王铁军; 胡林彦; 郑占申; 沈毅

    2005-01-01

    利用柠檬酸盐溶胶-凝胶法低温合成施主掺杂的BaTiO3粉体,在此基础上制备出Y、Sr掺杂的PTC陶瓷.最后用DTA、TGA对粉体合成的历程进行了分析,用SEM、TEM和EDS对Y、Sr掺杂陶瓷的晶粒大小、形貌、电畴以及Ca的影响进行了分析.

  10. Processing, properties, and application of textured 0.72lead(magnesium niobate)-0.28lead titanate ceramics

    Science.gov (United States)

    Brosnan, Kristen H.

    In this study, XRD and electron backscatter diffraction (EBSD) techniques were used to characterize the fiber texture in oriented PMN-28PT and the intensity data were fit with a texture model (the March-Dollase equation) that describes the texture in terms of texture fraction (f), and the width of the orientation distribution (r). EBSD analysis confirmed the orientation of the microstructure, with no distinguishable randomly oriented, fine grain matrix. Although XRD rocking curve and EBSD data analysis gave similar f and r values, XRD rocking curve analysis was the most efficient and gave a complete description of texture fraction and texture orientation (f = 0.81 and r = 0.21, respectively). XRD rocking curve analysis was the preferred approach for characterization of the texture volume and the orientation distribution of texture in fiber-oriented PMN-PT. The dielectric, piezoelectric and electromechanical properties for random ceramic, 69 vol% textured, 81 vol% textured, and single crystal PMN-28PT were fully characterized and compared. The room temperature dielectric constant at 1 kHz for highly textured PMN-28PT was epsilonr ≥ 3600 with low dielectric loss (tan delta = 0.004). The temperature dependence of the dielectric constant for 81 vol% textured ceramic followed a similar trend as the single crystal PMN-28PT up to the rhombohedral to tetragonal transition temperature (TRT) at 104°C. 81 vol% textured PMN-28PT consistently displayed 60 to 65% of the single crystal PMN-28PT piezoelectric coefficient (d33) and 1.5 to 3.0 times greater than the random ceramic d33 (measured by Berlincourt meter, unipolar strain-field curves, IEEE standard resonance method, and laser vibrometry). The 81 vol% textured PMN-28PT displayed similarly low piezoelectric hysteresis as single crystal PMN-28PT measured by strain-field curves at 5 kV/cm. 81 vol% textured PMN-28PT and single crystal PMN-28PT displayed similar mechanical quality factors of QM = 74 and 76, respectively. The

  11. 微乳液-共沉淀-煅烧法制备不同形貌的钛酸钡纳米粒子%PREPARATION OF BARIUM TITANATE NANOPARTICLES WITH DIFFERENT MORPHOLOGIES BY THE MICROEMULSION-COPRECIPITATION-CALCINATION METHOD

    Institute of Scientific and Technical Information of China (English)

    孙旭峰; 朱启安; 赵蓉芳; 张琪; 龚敏; 张超

    2008-01-01

    A precursor, BaTiO(C2O4)2-4H2O, was synthesized in reverse microemulsion consisting of water, t-octylphenoxypolye-thoxyethanol, n-hexanol and cyclohexane, using Ti(OC4H9)4,H2C2O4-2H2O and BaCl2-2H2O as starting materials. Barium titanate (BaTiO3) spherical nanoparticles with diameters of 40-80nm and BaTiO3 rod-like nanoparticles with diameters of 50-80nm and lengths of 180-300nm were fabricated by calcining the precursors at 700℃ for 4h and were characterized by X-ray diffraction, transmission electron microscope, selected area electronic diffraction, Fourier transform infrared spectroscopy, and thermogravimetry. The results show that the as-prepared BaTiO3 nanoparticles with uniform sizes and a single crystal structure belong to a cubic crystal system. The sizes and morphologies of BaTiO3 nanoparticles can be controlled by changing the molar ratio of water to surfactant.%以Ti(OC4H9)4,H2C2O4-2H2O和BaCl2-2H2O为原料,在水溶液/辛基酚聚氧乙烯(9)醚/正己醇/环己烷反相微乳液体系中制得了前驱体BaTiO(C2O4)2-4H2O.在700℃煅烧前驱体BaTiO(C2O4)2-4H2O4h分别制得直径约为40~80nm的BaTiO3球形纳米粒子和长约180~300nm、直径为50~80nm的BaTiO3纳米棒.用X射线衍射、透射电镜、选区电子衍射、Fourier红外光谱分析和热重分析表征了所制备的BaTiO3纳米粒子的结构和性能.结果表明:所制备的BaTiO3纳米粒子大小均匀,属立方相,具有单晶结构.改变水与表面活性剂的摩尔比能控制BaTiO3纳米粒子的大小和形貌.

  12. Mechanism of the Pyroelectric Response under Direct-Current Bias in La-Modified Lead Zirconate Titanate Stannate Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-Ling; WANG Gen-Shui; CHEN Xue-Feng; CAO Fei; DONG Xian-Lin; GU Yan; HE Hong-Liang; LIU Yu-Sheng

    2011-01-01

    Dielectric and pyroelectric properties ofPbo.97Lao.o2(Zro.42Sno.4oTio.i8)03 ceramics are investigated as functions of temperature and dc bias field. Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed. It is found that the sign, value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases. Polarization and depolarization processes under dc biases are analyzed. Besides the contribution of pind, the diffuse and decreased pyroelectric response under dc bias compared with that of an identical Geld poled sample without dc bias is mainly attributed to the depolarization process under dc bias.%@@ Dielectric and pyroelectric properties of Pbo.s7Lao.o2(Zro.42Sno.4OTio.is)O3 ceramics are investigated as functions of temperature and do bias field.Induced and intrinsic pyroelectric coefficients pind and p0 are calculated and analyzed.It is found that the sign,value and variation of the net pyroelectric coefficient p with increasing dc bias all are dominated by p0 under applied biases.Polarization and depolarization processes under do biases are analyzed.Besides the contribution of pind,the diffuse and decreased pyroelectric response under do bias compared with that of an identical field poled sample without do bias is mainly attributed to the depolarization process under do bias.

  13. 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)

  14. Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

    Institute of Scientific and Technical Information of China (English)

    曾涛; 漏琦伟; 陈学锋; 张红玲; 董显林; 王根水

    2015-01-01

    The phase transitions, dielectric properties, and polarization versus electric field (P–E ) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58−xTix)O3 (0.13≤x≤0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P–E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content.

  15. Preparation of Bismuth Titanate Piezoelectric Ceramic Thick Film%钛酸铋压电陶瓷厚膜的制备

    Institute of Scientific and Technical Information of China (English)

    赵欣欣; 张帆

    2013-01-01

    Bismuth titanate (BIT) powders were prepared from bismuth nitrate, titanium tetrabutoxide and oxalic acid by the chemical coprecipitation method. Then BIT ceramic thick film was prepared by screen-printing method, and its crystal structure was characterized by XRD and SEM analysis, effect of calcination temperature on the orientation degree was also studied. The results show that BIT powders with single phase can be obtained by calcination at 650 oC for 2 h, nanoparticles whose particle size is smaller than1 µm can be obtained by ball milling;the grain orientation (00k) of BIT thick film prepared by sintering at 1 200 oC for 2 h with the heating rate of 10 oC/min is high, can reach to 95.5%.%  以五水硝酸铋草酸和钛酸四丁酯为原料,采用化学共沉淀法,制得钛酸铋(BIT)粉体。然后﹑采用多层晶粒生长法,通过丝网印刷制得BIT压电陶瓷厚膜。借助XRD和SEM对产物晶体结构进行表征,并研究烧结温度对取向度的影响。结果表明,650 oC煅烧2 h可获得单一晶相的BIT粉体,经球磨后得到粒径小于1μm纳米粉体。1200 oC,升温速率10 oC/min,保温2 h时烧结的BIT厚膜在(00k)方向上取向度最高,达到95.50%。

  16. Effects of Copper Doping on Dielectric and A.C. Conductivity in Layered Sodium Tri-Titanate Ceramic

    Science.gov (United States)

    Shripal; Dwivedi, Shailja; Singh, Rakesh; Tandon, R. P.

    2013-09-01

    Electron paramagnetic resonance (EPR) spectra of 0.01, 0.1 and 1.0 molar percentage (mp) of CuO doped derivatives of layered Na2Ti3O7 ceramic have been reported. The results show that copper substitutes as Cu2+ at Ti4+ octahedral sites. From the dependence of loss tangent (tan δ) and the relative permittivity (ɛ‧) on temperature and frequency, it is concluded that all the derivatives are of polar nature. The relaxation peaks at lower temperatures have been attributed to the presence of different types of dipoles, whereas peaks in the higher temperature region indicate possible ferroelectric phase transition. The dependence of conductivity on temperature show that electron hopping (polaron) conduction exists in a wide span of temperature range. However, the associated interlayer ionic conduction exists in a small temperature range. Interlayer alkali ion hopping mechanism of conduction has been proposed toward higher temperatures. The conductivity versus frequency plots reveal that the polaron conduction plays a prominent role toward the lower temperature side that diminishes with the rise in temperature. The most probable relaxation times for 0.01 and 0.1 mp CuO doped derivatives are almost same but it records an increased value for 1.0 mp doped material. This again attributes to the possible change in the symmetry of copper environment.

  17. Infrared Spectroscopic, X-ray and Nanoscale Characterization of Strontium Titanate Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J. D.; Moutinho, H. R.; Kazmerski, L. L.; Mueller, C. H.; Rivkin, T. V.; Treece, R. E.; Dalberth, M.; Rogers, C. T.

    1997-01-01

    Attenuated total reflectance (ATR) measurements were performed using Fourier transform infrared (FTIR) spectroscopy in the ATR mode with a thallium iodobromide (KRS-5) crystal to measure the frequencies of the v{sub 3} and v{sub 4} phonon absorption bands in thin strontium titanate films deposited on single-crystal yttrium-barium copper oxide (YBCO), lanthanum aluminate, magnesium oxide, and strontium titanate substrates. The KRS-5 crystal enabled FTIR-ATR measurements to be made at frequencies above 400 cm-1. Atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements were also made to further characterize the films. The measurements were repeated on single-crystal specimens of strontium titanate and the substrates for comparison. Softening in the frequency of the v{sub 4} transverse optical phonon in the lattice-mismatched films below the established value of 544 cm-1 is indicative of the highly textured, polycrystalline ceramic nature of the films and is consistent with the XRD and AFM results.

  18. Infrared spectroscopic, x-ray, and nanoscale characterization of strontium titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J.D.; Moutinho, H.R.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States); Mueller, C.H.; Rivkin, T.V.; Treece, R.E. [Superconducting Core Technologies, Inc., Golden, CO (United States); Dalberth, M.; Rogers, C.T. [Colorado Univ., Boulder, CO (United States). Dept. of Physics

    1996-04-01

    Attenuated total reflectance (ATR) measurements were performed using Fourier transform infrared (FTIR) spectroscopy in the ATR mode with a thallium iodobromide (KRS-5) crystal to measure the frequencies of the {nu}{sub 3} and {nu}{sub 4} phonon absorption bands in thin strontium titanate films deposited on single-crystal yttrium-barium copper oxide (YBCO), lanthanum aluminate, magnesium oxide, and strontium titanate substrates. The KRS-5 crystal enabled FTIR-ATR measurements to be made at frequencies above 400 cm{sup {minus}1}. Atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements were also made to further characterize the films. The measurements were repeated on single-crystal specimens of strontium titanate and the substrates for comparison. Softening in the frequency of the {nu}{sub 4} transverse optical phonon in the lattice- mismatched films below the established value of 544 cm{sup {minus}1} is indicative of the highly textured, polycrystalline ceramic nature of the films and is consistent with the XRD and AFM results.

  19. Effect of Excess Lead and Bismuth Content on the Electrical Properties of High-Temperature Bismuth Scandium Lead Titanate Ceramics

    Science.gov (United States)

    Sehirlioglu, Alp; Sayir, Ali

    2008-01-01

    Aeronautic and aerospace applications require piezoelectric materials that can operate at high temperatures. The air-breathing aeronautic engines can use piezoelectric actuators for active combustion control for fuel modulation to mitigate thermo-acoustic instabilities and/or gas flow control to improve efficiency. The principal challenge for the insertion of piezoelectric materials is their limitation for upper use temperature and this limitation is due low Curie temperature and increasing conductivity. We investigated processing, microstructure and property relationship of (1-x)BiScO3-(x)PbTiO3 (BS-PT) composition as a promising high temperature piezoelectric. The effect of excess Pb and Bi and their partitioning in grain boundaries were studied using impedance spectroscopy, ferroelectric, and piezoelectric measurement techniques. Excess Pb addition increased the grain boundary conduction and the grain boundary area (average grain size was 24.8 m, and 1.3 m for compositions with 0at.% and 5at.% excess Pb, respectively) resulting in ceramics with higher AC conductivity (tan d= 0.9 and 1.7 for 0at.% and 5at.% excess Pb at 350 C and at 10kHz) that were not resistive enough to pole. Excess Bi addition increased the resistivity (rho= 4.1x10(exp 10) Omega cm and 19.6 x10(exp 10) Omega.cm for compositions with 0at.% and 5at.% excess Bi, respectively), improved poling, and increased the piezoelectric coefficient from 137 to 197 pC/N for 5at.% excess Bi addition. In addition, loss tangent decreased more than one order of magnitude at elevated temperatures (greater than 300 C). For all compositions the activation energy of the conducting species was similar (approximately equal to 0.35-0.40 eV) and indicated electronic conduction.

  20. Phase transition characteristics and dielectric properties of rare-earth (La, Pr, Nd, Gd) doped Ba(Zr0.09Ti0.91)O-3 ceramics

    OpenAIRE

    2010-01-01

    A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba1−yLn2y/3)Zr0.09Ti0.91O3 (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and diel...

  1. Temperature dependence on the electrical properties of Ba(Ti{sub 0.90}Zr{sub 0.10})O{sub 3}:2V ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Moura, F. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Federal de Itajuba-Unifei - Campus Itabira, Rua Sao Paulo 377, Bairro: Amazonas, CEP 35900-37, Itabira, MG (Brazil); Paskocimas, C.A.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-01

    Barium zirconium titanate ferroelectric ceramics modified with vanadium Ba(Ti{sub 0.90}Zr{sub 0.10}V{sub 0.02})O{sub 3} (BZT:2V) were prepared from powders synthesized using the mixed oxide method. The effect of temperature on the structural and electrical properties of BZT:2V ceramics was investigated. X-ray diffraction data evidenced no secondary phases. As temperature decreases, the maximum dielectric permittivity decreased. The fine-grained sample showed a 'relaxor-like' ferroelectric behavior. The dielectric permittivity reaches a maximum value ({epsilon}{sub m} {approx} 16,000 at 1 kHz) for the BZT:2V ceramics sintered at 1623 K for 4 h. Remnant polarization (P{sub r}) and coercive field were also temperature dependent.

  2. THE APPLICATION OF STEREOLOGY METHOD FOR ESTIMATING THE NUMBER OF 3D BaTiO3 – CERAMIC GRAINS CONTACT SURFACES

    Directory of Open Access Journals (Sweden)

    Vojislav V Mitić

    2011-05-01

    Full Text Available Methods of stereological study are of great importance for structural research of electronic ceramic materials including BaTiO3-ceramic materials. The broad application of ceramics, based on barium-titanate, in advanced electronics nowadays demands a constant research of its structure, that through the correlation structureproperties, a fundamental in the basic materials properties prognosis triad (technology-structure-properties, leads to further prognosis and properties design of these ceramics. Microstructure properties of BaTiO3- ceramic material, expressed in grains' boundary contact, are of basic importance for electric properties of this material, particularly the capacity. In this paper, a significant step towards establishing control under capacitive properties of BaTiO3-ceramics is being done by estimating the number of grains contact surfaces. Defining an efficient stereology method for estimating the number of BaTiO3-ceramic grains contact surfaces, we have started from a mathematical model of mutual grains distribution in the prescribed volume of BaTiO3-ceramic sample. Since the real microstructure morphology of BaTiO3-ceramics is in some way disordered, spherical shaped grains, using computer-modelling methods, are approximated by polyhedra with a great number of small convex polygons. By dividing the volume of BaTiO3-ceramic sample with the definite number of parallel planes, according to a given pace, into the intersection plane a certain number of grains contact surfaces are identified. According to quantitative estimation of 2D stereological parameters the modelled 3D internal microstructure is obtained. Experiments were made by using the scanning electronic microscopy (SEM method with the ceramic samples prepared under pressing pressures up to 150 MPa and sintering temperature up to 1370°C while the obtained microphotographs were used as a base of confirming the validity of presented stereology method. This paper, by applying

  3. Perovskite ceramic nanoparticles in polymer composites for augmenting bone tissue regeneration

    Science.gov (United States)

    Bagchi, Amrit; Rama Krishna Meka, Sai; Narayana Rao, Badari; Chatterjee, Kaushik

    2014-12-01

    There is increasing interest in the use of nanoparticles as fillers in polymer matrices to develop biomaterials which mimic the mechanical, chemical and electrical properties of bone tissue for orthopaedic applications. The objective of this study was to prepare poly(ɛ-caprolactone) (PCL) nanocomposites incorporating three different perovskite ceramic nanoparticles, namely, calcium titanate (CT), strontium titanate (ST) and barium titanate (BT). The tensile strength and modulus of the composites increased with the addition of nanoparticles. Scanning electron microscopy indicated that dispersion of the nanoparticles scaled with the density of the ceramics, which in turn played an important role in determining the enhancement in mechanical properties of the composite. Dielectric spectroscopy revealed improved permittivity and reduced losses in the composites when compared to neat PCL. Nanofibrous scaffolds were fabricated via electrospinning. Induction coupled plasma-optical emission spectroscopy indicated the release of small quantities of Ca+2, Sr+2, Ba+2 ions from the scaffolds. Piezo-force microscopy revealed that BT nanoparticles imparted piezoelectric properties to the scaffolds. In vitro studies revealed that all composites support osteoblast proliferation. Expression of osteogenic genes was enhanced on the nanocomposites in the following order: PCL/CT > PCL/ST > PCL/BT > PCL. This study demonstrates that the use of perovskite nanoparticles could be a promising technique to engineer better polymeric scaffolds for bone tissue engineering.

  4. Permeability analysis for thermal binder removal from green ceramic bodies

    Science.gov (United States)

    Yun, Jeong Woo

    2007-12-01

    The permeability of unlaminated and laminated green tapes was determined as a function of binder content for binder removed by air oxidation. The tapes are comprised of barium titanate as the dielectric, and polyvinyl butyral and dioctyl phthalate as the main compoents of the binder mixture. The flow in porous media through the tapes was analyzed in terms of models for describing Knudsen, slip, and Poiseuille flow mechanisms. The characteristic pore size was determined to be 0.5-2 mum and thus Poiseuille flow was the dominant transport mechanism contributing to the flux. The permeability was then determined from Darcy's law for flow in porous media. The permeability was also determined from micro-structural attributes in terms of the specific surface, the pore fraction, and terms to account for tortuosity and constrictions. The permeability and adhesion strength of laminated green ceramic tapes were determined as a function of lamination conditions of time, temperature, and pressure.

  5. 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.)

  6. High-Performance Protonic Ceramic Fuel Cells with Thin-Film Yttrium-Doped Barium Cerate-Zirconate Electrolytes on Compositionally Gradient Anodes.

    Science.gov (United States)

    Bae, Kiho; Lee, Sewook; Jang, Dong Young; Kim, Hyun Joong; Lee, Hunhyeong; Shin, Dongwook; Son, Ji-Won; Shim, Joon Hyung

    2016-04-13

    In this study, we used a compositionally gradient anode functional layer (AFL) consisting of Ni-BaCe(0.5)Zr(0.35)Y(0.15)O(3-δ) (BCZY) with increasing BCZY contents toward the electrolyte-anode interface for high-performance protonic ceramic fuel cells. It is identified that conventional homogeneous AFLs fail to stably accommodate a thin film of BCZY electrolyte. In contrast, a dense 2 μm thick BCZY electrolyte was successfully deposited onto the proposed gradient AFL with improved adhesion. A fuel cell containing this thin electrolyte showed a promising maximum peak power density of 635 mW cm(-2) at 600 °C, with an open-circuit voltage of over 1 V. Impedance analysis confirmed that minimizing the electrolyte thickness is essential for achieving a high power output, suggesting that the anode structure is important in stably accommodating thin electrolytes.

  7. DIELECTRIC AND PYROELECTRIC PROPERTIES OF THE COMPOSITES OF FERROELECTRIC CERAMIC AND POLY(VINYL CHLORIDE

    Directory of Open Access Journals (Sweden)

    M.Olszowy

    2003-01-01

    Full Text Available The dielectric and pyroelectric properties of lead zirconate titanate/poly(vinyl chloride [PZT/PVC] and barium titanate/poly(vinyl chloride [BaTiO3/ PVC] composites were studied. Flexible composites were fabricated in the thin films form (200-400 μm by hot-pressed method. Powders of PZT or BaTiO3 in the shape of ≤ 75 μm ceramics particles were dispersed in a PVC matrix, providing composites with 0-3} connectivity. Distribution of the ceramic particles in the polymer phase was examined by scanning electron microscopy. The analysis of the thermally stimulated currents (TSC have also been done. The changes of dielectric and pyroelectric data on composites with different contents of ceramics up to 40% volume were investigated. The dielectric constants were measured in the frequency range from 600 Hz to 6 MHz at room temperature. The pyroelectric coefficient for BaTiO3/PVC composite at 343 K is about 35 μC/m2K which is higher than that of β-PVDF (10 μC/m2 K.

  8. 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.

  9. Effects of X-Ray Irradiation and Barium Deficiency on Grain Boundary States in BaTiO3:Ta Ceramics

    Science.gov (United States)

    Uchida, Yoshiharu; Kai, Ayako; Murata, Takuya; Miki, Toshikatsu

    2004-02-01

    The effects of x-irradiation and Ba deficiency in BaTiO3:Ta ceramics were investigated in conjunction with the mechanism of an abrupt increase in electrical resistivity at the Curie temperature Tc, which was called the mode-I positive temperature coefficient of resistivity (PTCR). X-irradiation decreases the resistivity and the potential barrier height at grain boundaries in the rhombohedral and cubic specimens, but increases the ESR intensity of a singlet signal at g=2.005. On the other hand, introducing Ba deficiency increases the room-temperature resistivity ρRT and the magnitude of resistivity jump ρmode-I at Tc, but both ρRT and ρmode-I become to decrease when Ba deficiency exceeds 0.03 at%. In highly Ba-deficient specimens, the singlet ESR signal also decreases with increasing Ba deficiency. For explaining the irradiation effects, we proposed two models. One is the hole-recombination model, in which trapped-electrons at VBa-associated acceptor levels recombine with the holes created by irradiation. The other is the electron-detrapping model for the electrons trapped by acceptor levels. The explanation of the effects of x-irradiation and Ba deficiency was attempted by assuming VBa-associated centers (VBa, VBa-VO, VBa-F and VBa-F+). We conclude that predominant acceptor states at grain boundaries are VBa-VO-type defects. It is considered that the mode-I PTCR originats from critical changes in the density of states (DOS) of VBa-VO and the Fermi energy at tetragonal-to-cubic transition. This type of trap activation may lead to the formation of VBa-F+ and VBa-F from VBa-VO.

  10. Barium periostitis: an intraoral complication following barium swallow.

    Science.gov (United States)

    Stanton, David C; Seeger, Douglas; Robinson, Brian T

    2007-05-01

    Barium is used with great frequency for various gastrointestinal radiographic studies. Complications arising from the use of barium are uncommon and can range from peritonitis, pneumonitis, vascular intravasation, allergic reactions, and even "barium appendicitis." We report a case of an unusual complication, periostitis, from the use of barium in a 46-year-old male.

  11. Photoactive transparent nano-crystalline glass-ceramic for remazole red dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gad-Allah, Tarek A., E-mail: tareqabdelshafy@yahoo.ca [Water Pollution Research Department, National Research Centre, Cairo 12311 (Egypt); Margha, Fatma H. [Department of Glass Research, National Research Centre, Cairo 12311 (Egypt)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Preparation and characterization of novel transparent nanocrystalline glass-ceramic. ► Precipitation of photoactive phases by using controlled heat-treatment. ► Conservation of transparency along with photoactivity. ► Using the prepared nanocrystalline glass-ceramic in water purification. -- Abstract: Transparent glass ceramic material was prepared from alkali-borosilicate glass containing titania by proper heat treatment scheme. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, transmission electron microscope, selected area electron diffraction and UV–visible spectroscopy. The applied heat treatment program allowed the crystallization of nano-crystalline anatase, rutile, barium titanate, titanium borate and silicate phases while maintaining the transparency. The precipitated nano-crystalline anatase and rutile phases were responsible for the observed high photocatalytic activity of the prepared samples. Samples of 24.29 and 32.39 TiO{sub 2} wt% showed better efficiency for the decolorization of remazole red dye compared with commercial-TiO{sub 2} used in preparation of glass-ceramic. The reuse of prepared glass-ceramic photocatalyst with nearly same efficiency for different times was also proved.

  12. 倒车雷达用锆钛酸铅压电陶瓷材料的研究%Study on Lead Zirconate Titanate Piezoelectric Ceramic Materials for Reversing Radar

    Institute of Scientific and Technical Information of China (English)

    文理; 刘玉红

    2015-01-01

    对锆钛酸铅陶瓷材料进行了Nb2 O5、 SrCO3微量掺杂改性研究,观察了掺杂后陶瓷样品的显微结构,研究了其相对介电常数、压电常数、机电耦合系数及电容量变化率随测试温度变化的规律。实验结果表明: Nb2 O5、 SrCO3掺杂后,陶瓷结构致密,介电损耗减少,相对介电常数、压电常数、机电耦合系数明显提高,电容量变化率明显改善。当Nb2 O5、 SrCO3的添加量为0.6wt%时,制得的压电陶瓷材料具有最佳的压电性能:εr=2100, D33=450 pC/N, Kp=0.81,ΔC/C<10%(-55~85℃),可以满足高性能的汽车倒车雷达的应用要求。%The lead zirconate titanate ceramic materials doped with Nb2 O5 , SrCO3 were studied.The microstructures of the doped ceramic samples were observed.Relative dielectric constant, piezoelectric constant, electromechanical coupling coefficient and capacitance change rates with test temperature were studied.The experimental results showed that Nb2 O5 , SrCO3 doping on ceramic, the ceramic becomes denser, the dielectric loss reduces, the relative dielectric constants, piezoelectric constant, electromechanical coupling coefficient increased evidently, the capacitance change rate improved obviously.When the adding amount of Nb2 O5 , SrCO3 was 0.6wt%, the piezoelectric ceramic material prepared had the best piezoelectric poperties,εr=2100, D33=450 pC/N, Kp=0.81, ΔC/C<10%(-55~85 ℃), can meet the requirements of high performance car reversing radar’s.

  13. Comparison of the properties of tonpilz transducers fabricated with 001 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

    Science.gov (United States)

    Brosnan, Kristen H; Messing, Gary L; Markley, Douglas C; Meyer, Richard J

    2009-11-01

    Tonpilz transducers are fabricated from 001 fiber-textured 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO(3) template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.

  14. Kaolinite as a Suspending Agent for Preparation of Porous BaTiO3 Ceramics via Freeze Casting

    Science.gov (United States)

    Li, Pin; Pu, Yongping; Dong, Zijing; Gao, Pan

    2014-02-01

    Porous barium titanate (BT) ceramics were fabricated by a freeze-casting technique with kaolinite as a suspending agent, and the effects of the kaolinite content on the microstructure and dielectric properties were investigated. The porous BT ceramics possessed high porosity and a unique two-dimensional pore structure along the freezing direction. The absolute value of the zeta potential and the viscosity of the slurry increased with increasing kaolinite content. The zeta potential plot and viscosity characterization results showed that a stable slurry was obtained when the kaolinite content was 8 wt.%. The porosity was substantially affected by the suspension effect and the fluxing action of the kaolinite. Porosity characterization showed that the porosity of the porous BT ceramic reached a maximum value for 8 wt.% addition of kaolinite. Scanning electron microscopy showed that the porous BT ceramics possessed a multilayered channel structure. The temperature dependence of the permittivity showed that the porous BT ceramics possessed good temperature stability of the dielectric constant.

  15. A comparison of different powder compaction processes adopted for synthesis of lead-free piezoelectric ceramics

    Science.gov (United States)

    Mahesh, M. L. V.; Bhanu Prasad, V. V.; James, A. R.

    2016-04-01

    Barium zirconium titanate, Ba(Zr0.15Ti0.85)O3 nano-crystalline powders were synthesized using high energy ball milling. The calcined powders were compacted adopting two different approaches viz. the conventional uniaxial pressing and cold-isostatic pressing (CIP) and the compacts were sintered at 1350 °C. A single phase perovskite structure was observed in both cases. BZT ceramics compacted using CIP technique exhibited enhanced dielectric and ferroelectric properties compared to ceramics compacted by uniaxial pressing. The polarization current peaks have been used in this paper as an experimental evidence to prove the existence of ferroelectricity in the BZT ceramics under study. The peak polarization current was found to be ~700% higher in case of cold iso-statically compacted ceramics. Similarly electric field induces strain showed a maximum strain ( S max) of 0.08% at an electric field of 28 kV/cm. The dielectric and ferroelectric properties observed are comparable to single crystals of the same material.

  16. Parameter Optimization in the Synthesis of BZT Ceramics to Achieve Good Dielectric Properties

    Directory of Open Access Journals (Sweden)

    A. Frattini

    2013-01-01

    Full Text Available The powder synthesis of barium zirconate titanate (BZT (BaZrTiO3 from the mechanochemical activation of BaCO3, ZrO2, and TiO2 was studied. The grinding effect, by using a planetary ball milling, on the crystallization temperature of BZT powders was analyzed. X-ray diffractometry, differential thermal analysis, thermogravimetric analysis, and scanning electronic microscopy (SEM were used as characterization methods. The crystallization behavior of powders activated by high-energy grinding and the effect of grinding time on the BZT crystallization were analyzed. After grinding by 4 h, the BaZr(0.05Ti(0.95O3 sample was almost fully crystallized at . The results of dielectric and ferroelectric properties show that high-energy ball milling is a practical and promising way to prepare BZT ceramics.

  17. 复合稳定剂对钛酸铝陶瓷性能的影响%The Inlfuences of Composite Stabilizer on the Properties of Aluminum Titanate Ceramics

    Institute of Scientific and Technical Information of China (English)

    桑月侠; 刘维良; 郑乃章; 曾小军

    2015-01-01

    以氧化铝(α-A12O3)粉和氧化钛(TiO2)粉为主要原料,以ZrO2、ZnO、MgO、Y2O3、La2O3为稳定剂,摩尔比为1∶1∶1∶2∶2,采用固相反应法制备出钛酸铝陶瓷。研究了复合稳定剂对钛酸铝陶瓷抗弯强度、热稳定性和显微结构的影响。采用热膨胀系数测定仪、万能试验机、X射线衍射仪、扫描电镜等对样品性能进行了表征。实验结果表明,当复合稳定剂含量为25wt.%,烧成温度为1550℃,保温时间为3h时制备的钛酸铝陶瓷性能最佳。其热膨胀系数为0.86×10-6/℃,比无稳定剂的钛酸铝陶瓷降低了35.8%;抗弯强度为48.3MPa,比无稳定剂的钛酸铝陶瓷提高了36.9%。%Low thermal expansion aluminum titanate ceramics were prepared by solid state reaction method. The method employed Al2O3and TiO2 powders as raw materials, ZrO2, ZnO, MgO, Y2O3 and La2O3 as stabilizers. The mol ratio of ZrO2/ZnO/MgO/Y2O3/La2O3 was 1:1:1:2:2. The inlfuences of composite stabilizer on lfexural strength, thermal stability and microstructure of Al2TiO5 ceramic were studied. Samples were characterized by means of thermal expansion coefifcient measuring instrument, tensile testing machine, X-ray diffraction and scanning electron microscope. The experimental results indicated that the properties of Al2TiO5 ceramic was best when the stabilizer content was 25wt%, the ifring temperature was 1450°C and the holding time was 3h. Al2TiO5 ceramic was 0.86×10-6 /°C in thermal expansion coefifcient, and decreased by 35.8%. Al2TiO5ceramic was 48.3MPa in lfexural strength, and increased by 36.9%.

  18. Effect on the grain size of single-mode microwave sintered NiCuZn ferrite and zinc titanate dielectric resonator ceramics.

    Science.gov (United States)

    Sirugudu, Roopas Kiran; Vemuri, Rama Krishna Murthy; Venkatachalam, Subramanian; Gopalakrishnan, Anisha; Budaraju, Srinivasa Murty

    2011-01-01

    Microwave sintering of materials significantly depends on dielectric, magnetic and conductive Losses. Samples with high dielectric and magnetic loss such as ferrites could be sintered easily. But low dielectric loss material such as dielectric resonators (paraelectrics) finds difficulty in generation of heat during microwave interaction. Microwave sintering of materials of these two classes helps in understanding the variation in dielectric and magnetic characteristics with respect to the change in grain size. High-energy ball milled Ni0.6Cu0.2Zn0.2Fe1.98O4-delta and ZnTiO3 are sintered in conventional and microwave methods and characterized for respective dielectric and magnetic characteristics. The grain size variation with higher copper content is also observed with conventional and microwave sintering. The grain size in microwave sintered Ni0.6Cu0.2Zn0.2Fe1.98O4-delta is found to be much small and uniform in comparison with conventional sintered sample. However, the grain size of microwave sintered sample is almost equal to that of conventional sintered sample of Ni0.3Cu0.5Zn0.2Fe1.98O4-delta. In contrast to these high dielectric and magnetic loss ferrites, the paraelectric materials are observed to sinter in presence of microwaves. Although microwave sintered zinc titanate sample showed finer and uniform grains with respect to conventional samples, the dielectric characteristics of microwave sintered sample are found to be less than that of conventional sample. Low dielectric constant is attributed to the low density. Smaller grain size is found to be responsible for low quality factor and the presence of small percentage of TiO2 is observed to achieve the temperature stable resonant frequency.

  19. Nanodesigning of Hierarchical Multifunctional Ceramics

    Science.gov (United States)

    1993-09-28

    conditions by reacting nanosized titanium oxide or titanium alkoxides with a solution of barium hydroxide. The powders produced by this approach range in...14 1.2.5 Density of Colloidal Aggregated Network Near a Hard Wall ...... 15 1.2.6 Synthesis of Lead- Zirconium -Titanate (Pb(Zr0.5 2Tio.4 8)0 3 ) (PZT...6 Figure 4: Spinnability map for poly(ethylene oxide )-based a-A120 3 suspensions ......... 9 Figure 5: High

  20. Dielectric properties of doped titanates of transition metals in the millimeter-wavelength range

    Science.gov (United States)

    Rinkevich, A. B.; Perov, D. V.; Kuznetsov, E. A.; Pakhomov, Ya. A.; Ryabkov, Yu. I.

    2016-06-01

    Dielectric properties of ceramic titanates of nickel, cobalt, and manganese and their isomorphically substituted solid solutions are studied. Iron and magnesium are used as dopants. Original methods for solid-state synthesis of titanates allow variations in the dispersity of products. The structure and phase composition of products are analyzed. Microwave measurements of permittivity are performed in a frequency interval of 12-38 GHz. Real and imaginary parts of the permittivities of titanates are determined.

  1. A hybrid phenomenological model for ferroelectroelastic ceramics. Part I: Single phased materials

    Science.gov (United States)

    Stark, S.; Neumeister, P.; Balke, H.

    2016-10-01

    In this part I of a two part series, a rate-independent hybrid phenomenological constitutive model applicable for single phased polycrystalline ferroelectroelastic ceramics is presented. The term "hybrid" refers to the fact that features from macroscopic phenomenological models and micro-electromechanical phenomenological models are combined. In particular, functional forms for a switching function and the Helmholtz free energy are assumed as in many macroscopic phenomenological models; and the volume fractions of domain variants are used to describe the internal material state, which is a key feature of micro-electromechanical phenomenological models. The approach described in this paper is an attempt to combine the advantages of macroscopic and micro-electromechanical material models. Its potential is demonstrated by comparison with experimental data for barium titanate. Finally, it is shown that the model for single phased materials cannot reproduce the material behavior of morphotropic PZT ceramics based on a realistic choice for the material parameters. This serves as a motivation for part II of the series, which deals with the modeling of morphotropic PZT ceramics taking into account the micro-structural specifics of these materials.

  2. Controlling barium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Greenley, R.

    Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish, Louisiana, and the scale inhibitor squeeze operation are described. Based on the successful results obtained in treating this well, a generalized treating procedure for combating downhole scale deposition in high pressure/high temperature gas wells is presented. Formation squeezing with such an inhibitor represents a significant breakthrough for the oil and gas industry.

  3. 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...

  4. 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

  5. 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....

  6. Barium Titanate Film Interfaces for Hybrid Composite Energy Harvesters.

    Science.gov (United States)

    Bowland, Christopher C; Malakooti, Mohammad H; Sodano, Henry A

    2017-02-01

    Energy harvesting utilizing piezoelectric materials has become an attractive approach for converting mechanical energy into electrical power for low-power electronics. Structural composites are ideally suited for energy scavenging due to the large amount of mechanical energy they are subjected to. Here, a multifunctional composite with embedded sensing and energy harvesting is developed by integrating an active interface into carbon fiber reinforced polymer composites. By modifying the composite matrix, both rigid and flexible multifunctional composites are fabricated. Through electromechanical testing of a cantilever beam of the rigid composite, it reveals a power density of 217 pW/cc from only 1 g root-mean-square acceleration when excited at its resonant frequency of 47 Hz. Electromechanical sensor testing of the flexible multifunctional composite reveals an average voltage generation of 23.5 mV/g at its resonant frequency of 96 Hz. This research introduces a route for integrating nonstructural functionality into structural fiber composites by utilizing BaTiO3 coated woven carbon fiber fabrics with power scavenging and passive sensing capabilities.

  7. Abnormal grain growth in undoped strontium and barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Baeurer, M., E-mail: m.baeurer@ikm.uka.de [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe, Karlsruhe (Germany); Shih, S.-J.; Bishop, C. [Department of Materials, University of Oxford, Oxford (United Kingdom); Harmer, M.P. [Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA (United States); Cockayne, D. [Department of Materials, University of Oxford, Oxford (United Kingdom); Hoffmann, M.J. [Institut fuer Keramik im Maschinenbau, Universitaet Karlsruhe, Karlsruhe (Germany)

    2010-01-15

    Abnormal grain growth is a commonly observed phenomenon in perovskite materials. In order to study this phenomenon, grain growth experiments were conducted over a temperature range from 1425 to 1600 deg. C for the model system SrTiO{sub 3} to analyse the nucleation of abnormal grains and to identify the growth mechanism involved for normal and abnormal grains. Grain boundaries of normal and abnormal grains were investigated in quenched samples by high-resolution transmission electron microscopy and by energy-dispersive spectroscopy in a scanning transmission electron microscope. No amorphous film was observed at the grain boundaries for either normal or abnormal grains. Non-stoichiometry at the grain boundaries was identified as a possible reason for the differences in growth speed. The results are compared to the nucleation and growth of abnormal grains in BaTiO{sub 3}.

  8. Hot sputtering of barium strontium titanate on nickel foils

    Science.gov (United States)

    Aygün, Seymen M.; Daniels, Patrick; Borland, William; Maria, Jon-Paul

    2008-04-01

    The relationships linking temperature and voltage dependent dielectric response, grain size, and thermal budget during synthesis are illustrated. In doing so, it was found that maximizing thermal budgets within experimental bounds leads to electrical properties comparable to the best literature reports irrespective of the processing technique or microstructure. The optimal film properties include a bulk transition temperature, a room temperature permittivity of 1800, a voltage tuning ratio of 10:1 at 450 kV/cm, and a loss tangent less than 1.5% at 450 kV/cm. The sample set illustrates the well-known relationship between permittivity and crystal dimension, and the onset of a transition temperature shifts at very fine grain sizes. A brick wall model incorporating a high permittivity grain and a low permittivity grain boundary is used to interpret the dielectric data. However, the data show that high permittivity and tunability values can be achieved at grain sizes or film thicknesses that many reports associate with dramatic reductions in the dielectric response. These differences are discussed in terms of crystal quality and maximum processing temperature. The results collectively suggest that scaling effects in ferroelectric thin films are in many cases the result of low thermal budgets and the consequently high degree of structural imperfection and are not from the existence of low permittivity phases at the dielectric-electrode interface.

  9. Displacive Transformation in Ceramics

    Science.gov (United States)

    1994-02-28

    single cycle[21]. In zirconia , ferroelastic domains appeared during the cubic to tetragonal transformation at -2200’C, where [c] axes were elongated...Mechanism in Tetragonal Zirconia ( TZP ) Ceramics," Adv. in Ceramics 24 (1986) 653-662. 26. K. Mehta, J. F. Jue and A. V. Virkar, "Grinding-Liduced...barium copper oxide (YBa2Cu306+x) and dicalcium silicate (Ca 2 SiO4 ). The cubic to tetragonal transformation in PbTiO3 40 was proven to be

  10. Electric and microstructural characterization of densified ceramics of BaTiO3 obtained by pechini; Caracterizacion electrica y microestructural de ceramicas densificadas de BaTiO3 obtenido por pechini

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, C.; Rivera, E.; Rodriguez-Paez, J.E.

    2010-07-01

    The barium titanate BaTiO3 is a material of great technological interest due to their dielectric properties. The functionality of this mixed oxide is mainly determined by its structure. Different synthesis methods have been used to improve the electrical response of BaTiO3. In this work BaTiO3 powders were synthesized using the polymeric precursor method, Pechini, obtaining the compound at 650 C, with uniform nanometric particle size ({approx}20nm). The nature of the synthesized powders was analyzed using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results indicate that the crystalline phase present in the sample treated at 650 C is cubic and at 1100 C is tetragonal, with a relation c/a . 1.007. The samples sinterized at 1100 C showed a ferroelectric-paraelectric transition at a temperature of T . 123 C. The ceramic powders of barium titanate tetragonal, pressed and densified, was electrical characterizing with curves current-voltage (I-V) at different temperatures. Additionally, we measured the change in electrical resistance versus temperature (R-T) and we tested the behavior thermistor (PTCR) of the material for different pressures. Also the electric response of the material with the variation of the frequency, for different temperatures, was measured. (Author).

  11. Formation mechanism and characteristics of lanthanum-doped BaTiO{sub 3} powders and ceramics prepared by the sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ianculescu, Adelina Carmen [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); Vasilescu, Catalina Andreea, E-mail: katyvasilescu85@yahoo.com [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); National Institute for Lasers, Plasma and Radiation Physics, P.O. Box MG54, 077125 Magurele (Romania); Crisan, Maria; Raileanu, Malina [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vasile, Bogdan Stefan; Calugaru, Mihai [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); Crisan, Dorel; Dragan, Nicolae [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Curecheriu, Lavinia; Mitoseriu, Liliana [Department of Physics, Al. I. Cuza University of Iasi, Blvd. Carol I 11, 700506 Iasi (Romania)

    2015-08-15

    Pure and lanthanum-doped barium titanate nanopowders described by two different formulae, as Ba{sub 1−x}La{sub x}TiO{sub 3}, for lower La concentrations (0 ≤ x ≤ 0.005) and Ba{sub 1−x}La{sub x}Ti{sub 1−x/4}O{sub 3} for higher La concentration (x = 0.025) were prepared by an alkoxide sol–gel method. Single phase compositions were obtained after annealing at 900 °C for 2 h, in air. The increase of the lanthanum content causes structural and morphological changes in the oxide powders, including the evolution of the unit cell from tetragonal toward a cubic symmetry, the particle size decrease and a higher aggregation tendency. SEM investigations of the ceramics sintered at 1300 °C for 4 h indicate significant changes of the microstructural features (strong decrease of the average grain size and increase of the intergranular porosity) with the raise of La amount. Lanthanum addition to barium titanate prepared by sol–gel induces a more significant shift of the Curie temperature toward lower values, than that one reported in literature for ceramics of similar compositions, but processed by the conventional solid state method. The compositions with smaller La amount (x ≤ 0.005) show semiconducting properties at room temperature and high relative dielectric permittivity values, while the undoped ceramics and those doped with higher La content (x = 0.025) are good dielectrics. The ceramic with x = 0.025 exhibits acceptable low losses, a very diffuse ferroelectric–paraelectric transition and Curie temperature closed to the room temperature, being thus susceptible for high tunability applications. - Highlights: • Ba{sub 1−x}La{sub x}TiO{sub 3} (x ≤ 0.005) and Ba{sub 1−x}La{sub x}Ti{sub 1−x/4}O{sub 3} (x = 0.025) were prepared by sol–gel. • Ceramics with x < 0.5 exhibit semiconductor and high dielectric properties. • Ceramic with x = 0.025 exhibits acceptable low losses and diffuse phase transition.

  12. Analysis on Equilibrium Shape of Nano-precipitations at Grain Boundaries in Bismuth Doped Strontium Titanate Ceramics%铋掺杂钛酸锶陶瓷晶界纳米颗粒的平衡形状分析

    Institute of Scientific and Technical Information of China (English)

    邢娟娟; 顾辉

    2012-01-01

    利用透射电子显微镜对铋掺杂钛酸锶陶瓷晶界结构进行表征,在某些晶界处观测到不连续分布的纳米颗粒,尺寸为十几至一百多纳米,形状各有迥异.能谱分析结果表明这些纳米颗粒为金属铋.采用Cahn-Hoffmanξ矢量构建模型可以把晶界纳米颗粒形状定性地描述为相邻晶粒内两个独立平衡形状(Wulff形状)在晶界处的交集,两个平衡形状中心间的距离与晶界能相当.晶界纳米颗粒的平衡形状与两个独立平衡Wulff形状本身特征、相邻两侧晶粒的晶体学取向、晶界能和晶界的倾转以及颗粒本身尺寸等因素相关.%Grain boundary structures in Bi-doped strontium titanate ceramics were characterized by transmission electron microscope (TEM). Discontinuous nano-precipitations (NPs), whose sizes ranged from ten to over one hundred nanometers, were observed aligning along some grain boundaries. The composition of NP was detected as pure bismuth by spatial difference energy dispersive X-ray spectra (EDXS) method. Different shapes with facets were possessed by the NPs, indicating the anisotropy of NPs. The Cahn-Hoffman ζ-vector construction based on anisotropic surfaces was successfully applied to qualitatively describe the equilibrium shape of NP, which can be regarded as the intersection of two Wulff shapes at the grain boundaries. The distance between the two Wulff shapes centers is equal to the grain boundary energy. The Wulff shape itself, orientation of neighboring grains, grain boundary energy and grain boundary twist are considered as the important factors to affect the equilibrium shape of NP. Besides these, the size of NP will also influence the faceting of NP. This work is helpful to deepen the understanding of the microstructure evolvement during the sintering.

  13. Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO3 structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba(Ti1-xCex)O3(x=0.05, 0.10)(CBT) and(Ba1-yEuy)Ti1-y/8O3(y=0.05, 0.10)(EBT). Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO3 ceramics were discussed. The CBT ceramics exhibit a pseudo-cubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu2Ti2O7 phase. The Curie peak of BaTiO3 shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms(Eu≤5%), respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution(1 μm), a lower porosity and a higher density(5.85 g/cm3), more stable dielectric-temperature dependence(ε'=1600-1800 at t<50 ℃) and a lower dissipation factor(<0.05). The stability of dielectric constant with frequency in BaTiO3 can extend to 107 Hz due to Ce and Eu doping.

  14. On barium oxide solubility in barium-containing chloride melts

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V. [Ural Federal Univ., Yekaterinburg (Russian Federation). Inst. of High Temperature Electrochemistry

    2016-11-01

    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 BaCl{sub 2}-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-BaCl{sub 2}-MCl systems.

  15. Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells

    Science.gov (United States)

    Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

    2017-02-01

    In reducing the high operating temperatures (>=800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

  16. Advanced processing of lead titanate-polyimide composites for high temperature piezoelectric sensing

    NARCIS (Netherlands)

    Khanbareh, H.; Hegde, M.; Zwaag, S. van der; Groen, W.A.

    2015-01-01

    High performance polymer-ceramic composites are presented as promising candidates for high temperature piezoelectric sensing applications. lead-titanate (PT) ceramic particulate is incorporated into a polyetherimide polymer matrix, (PEI) at a specific volume fraction of 20% in the forms of 0-3 and q

  17. Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells.

    Science.gov (United States)

    Bae, Kiho; Jang, Dong Young; Choi, Hyung Jong; Kim, Donghwan; Hong, Jongsup; Kim, Byung-Kook; Lee, Jong-Ho; Son, Ji-Won; Shim, Joon Hyung

    2017-02-23

    In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.

  18. 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

  19. 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.

  20. The astrobiology of Titan

    Science.gov (United States)

    Raulin, F.; Coll, P.; Cabane, M.; Hebrard, E.; Israel, G.; Nguyen, M.-J.; Szopa, C.; Gpcos Team

    Largest satellite of Saturn and the only satellite in the solar system having a dense atmosphere, Titan is one of the key planetary bodies for astrobiological studies, due to several aspects: Its analogies with planet Earth, in spite of much lower temperatures, The Cassini-Huygens data have largely confirmed the many analogies between Titan and our own planet. Both have similar vertical temperature profiles, (although much colder, of course, on Titan). Both have condensable and non condensable greenhouse gases in their atmosphere. Both are geologically very active. Furthermore, the data also suggest strongly the presence of a methane cycle on Titan analogous to the water cycle on Earth. The presence of an active organic chemistry, involving several of the key compounds of prebiotic chemistry. The recent data obtained from the Huygens instruments show that the organic matter in Titan low atmosphere (stratosphere and troposphere) is mainly concentrated in the aerosol particles. Because of the vertical temperature profile in this part of the atmosphere, most of the volatile organics are probably mainly condensed on the aerosol particles. The nucleus of these particles seems to be made of complex macromolecular organic matter, well mimicked in the laboratory by the "Titan's tholins". Now, laboratory tholins are known to release many organic compounds of biological interest, such as amino acids and purine and pyrimidine bases, when they are in contact with liquid water. Such hydrolysis may have occurred on the surface of Titan, in the bodies of liquid water which episodically may form on Titan's surface from meteoritic and cometary impacts. The formation of biologically interesting compounds may also occur in the deep water ocean, from the hydrolysis of complex organic material included in the chrondritic matter accreted during the formation of Titan. The possible emergence and persistence of Life on Titan 1 All ingredients which seems necessary for Life are present on

  1. 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.

  2. 75 FR 33824 - Barium Chloride From China

    Science.gov (United States)

    2010-06-15

    ... COMMISSION Barium Chloride From China Determination On the basis of the record\\1\\ developed in the subject... order on barium chloride from China would be likely to lead to continuation or recurrence of material... Barium Chloride from China: Investigation No. 731-TA-149 (Third Review). By order of the...

  3. 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.

  4. 复相陶瓷铌酸锶钡/钛酸锶钡介电常数预测模型研究%Dielectric Constants Theory Model for (1-x)BaO·xSrO·0.5Nb2Os·0.5TiO2 Composite Ceramics

    Institute of Scientific and Technical Information of China (English)

    单连伟; 王继华; 马成国; 吴泽; 董丽敏; 韩志东; 张显友

    2011-01-01

    (1-x)BaO · x SrO · 0.5Nb2O5· 0.5TiO2 composite ceramics were prepared through powder-sol(P-S) process. X-ray diffraction(XRD) reveals that the tetragonal tungsten bronze phase and the perovskite phase coexist in the ceramics. Based on the Clausius-Mosotti equation, a dielectric constants theory model of barium strontium titanate(BST)/ strontium barium niobate (SBN) was established by the theoretical polarizability of BST and SBN. The results show that the experimental test value of dielectric constants is consistent with the calculation value via the theory model.%采用粉末-溶胶工艺制备了铌酸锶钡/钛酸锶钡(SBN/BST)复相陶瓷.X射线衍射研究表明钨青铜相和钙钛矿相共存于体系中.以Clausius(克劳修斯)-Mosotti(莫索缔)方程为基础,采用混合对数法则、铌酸锶钡和钛酸锶钡的理论极化率建立了SBN/BST的介电常数预测模型.结果表明:通过介电常数预测模型得到的数值与实验测试值相吻合.

  5. Clash of the Titans

    Science.gov (United States)

    Subramaniam, Karthigeyan

    2010-01-01

    WebQuests and the 5E learning cycle are titans of the science classroom. These popular inquiry-based strategies are most often used as separate entities, but the author has discovered that using a combined WebQuest and 5E learning cycle format taps into the inherent power and potential of both strategies. In the lesson, "Clash of the Titans,"…

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Titan: Callisto With Weather?

    Science.gov (United States)

    Moore, J. M.; Pappalardo, R. T.

    2008-12-01

    Instead of being endogenically active, Titan's interior may be cold and dead. Those landforms on Titan that are unambiguously identifiable can all be explained by exogenic processes (aeolian, fluvial, impact cratering, and mass wasting). At the scale of available imaging data, the surface is dominated by vast dune ergs and by fluvial erosion, transportation, and deposition. The sparse distribution of recognizable impact craters (themselves exogenic) is consistent with the presence of aeolian and fluvial activity sufficient to cover and or erode smaller craters, leaving only large ones. Previous suggestions of endogenically produced landforms have been, without exception, inconclusively identified. Features suggested to be cryovolcanic flows may be debris flows and other mass movements, facilitated by hydrocarbon-fluidized unconsolidated materials. Ganesa Macula has been suggested as a putative cryovolcanic dome, but it may simply be an impact structure that contains radar-dark dune or mass-wasted materials. Mountains, which are heavily modified by fluvial and mass wasting processes, could have formed as the scarps of large impact features and/or by slow contraction due to global cooling and freezing of an internal ammonia-water ocean, rather than by endogenically powered orogeny. A cold and inactive interior is consistent with an internal ammonia-water ocean, which has a peritectic temperature of 173K, easily obtained in Titan by radioactive decay alone in the absence of tidal heating. Titan's orbital eccentricity should have damped if its interior is warm and dissipative; instead, its high eccentricity can be ancient if the interior is assumed to be cold and non-dissipative. Indeed, it has been suggested that Titan may be non-hydrostatic, consistent with a thick ice shell and a cold and rigid interior. We suggest that the satellite most akin to Titan may be Callisto. Like Callisto, which may have formed relatively slowly in the outer circumjovian accretion disk

  12. Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Klaus Reichmann

    2015-12-01

    Full Text Available The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized.

  13. 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.

  14. 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.

  15. 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.

  16. Lightning not detected on Titan

    Science.gov (United States)

    Tretkoff, Ernie

    2011-05-01

    Scientists have speculated that lightning on Saturn's moon Titan could produce changes in atmospheric chemistry and could even spark production of organic compounds that could be precursors to the evolution of life, but so far there has been no conclusive detection of lightning on Titan. Extending previous searches for lightning on Titan, Fischer and Gurnett analyzed radio data up to the 72nd close flyby of Titan by the Cassini spacecraft. They found no evidence of lightning and concluded that if lightning occurs at all on Titan, it is probably a very rare event. (Geophysical Research Letters, doi:10.1029/2011GL047316, 2011)

  17. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  18. 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.

  19. 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.

  20. 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

  1. Tunable ferroelectric meta-material phase shifter embedded inside low temperature co-fired ceramics (LTCC)

    Science.gov (United States)

    Tork, Hossam S.

    This dissertation describes electrically tunable microwave devices utilizing low temperature co-fired ceramics (LTCC) and thick film via filled with the ferroelectric materials barium strontium titanate (BST) and barium zirconate titanate (BZT). Tunable ferroelectric capacitors, zero meta-material phase shifters, and tunable meta-material phase shifters are presented. Microwave phase shifters have many applications in microwave devices. They are essential components for active and passive phased array antennas and their most common use is in scanning phased array antennas. They are used in synthetic aperture radars (SAR), low earth orbit (LEO) communication satellites, collision warning radars, and intelligent vehicle highway systems (IVHS), in addition to various other applications. Tunable ferroelectric materials have been investigated, since they offer the possibility of lowering the total cost of phased arrays. Two of the most promising ferroelectric materials in microwave applications are BST and BZT. The proposed design and implementation in this research introduce new types of tunable meta-material phase shifters embedded inside LTCC, which use BST and BZT as capacitive tunable dielectric material controlled by changing the applied voltage. This phase shifter has the advantages of meta-material structures, which produce little phase error and compensation while having the simultaneous advantage of using LTCC technology for embedding passive components that improve signal integrity (several signal lines, power planes, and ground planes) by using different processes like via filling, screen printing, laminating and firing that can be produced in compact sizes at a low cost. The via filling technique was used to build tunable BST, BZT ferroelectric material capacitors to control phase shift. Finally, The use of the proposed ferroelectric meta-material phase shifter improves phase shifter performance by reducing insertion loss in both transmitting and receiving

  2. Effect of dielectrophoretic structuring on piezoelectric and pyroelectric properties of lead titanate-epoxy composites

    NARCIS (Netherlands)

    Khanbareh, H.; Zwaag, S. van der; Groen, W.A.

    2014-01-01

    Functional granular composites of lead titanate particles in an epoxy matrix prepared by dielectrophoresis show enhanced dielectric, piezoelectric and pyroelectric properties compared to 0-3 composites for different ceramic volume content from 10% to 50%. Two structuring parameters, the interparticl

  3. 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

  4. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... 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 review... revocation of the antidumping duty order on barium chloride from China would be likely to lead...

  5. 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

  6. 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.

  7. Preparation and Characterization of Nano-particle Substituted Barium Hexaferrite

    CERN Document Server

    Atassi, Yomen; Tally, Mohammad

    2014-01-01

    High density magnetic recording requires high coercivity magnetic media and small particle size. Barium hexaferrite has been considered as a leading candidate material because of its chemical stability, fairly large crystal anisotropy and suitable magnetic characteristics. In this work, we present the preparation of the hexagonal ferrite BaFe12O19 and one of its derivative; the Zn-Sn substituted hexaferrite by the chemical co-precipitation method. The main advantage of this method on the conventional glass-ceramic one, resides in providing a small enough particle size for magnetic recording. We demonstrate using the X-ray diffraction patterns that the particle size decreases when substituting the hexaferrite by the Zn-Sn combination. This may improve the magnetic properties of the hexaferrite as a medium for HD magnetic recording

  8. 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...

  9. 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.

  10. 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

  11. Microwave Dielectric Properties of Ceria Composite Lanthanum Sodium Titanate Dielectric Ceramics%氧化铈复合钛酸镧钠介质陶瓷的微波介电性能

    Institute of Scientific and Technical Information of China (English)

    钱俊

    2013-01-01

    Complex microwave dielectric ceramics (1 -x) (Na0.5La0.5 )TiO3+xCeO2 + 1%CuO were prepared by solid-state reaction method. The relation for sintering temperature, microstructure and microwave dielectric properties of the ceramics were studied. The results show that the ceramics with dielectric constant εr of 35. 9. quality factor of 11 300 GHz and temperature coefficient τf of 98. 0 × 10-5℃-1 were obtained when sintering temperature was 1 400℃ and x = 0. 8. By appropriately adjusted the x value, and a zero τf value could be achieved. When x was 0. 9 and sintering temperature was 1 400℃ . a microwave dielectric ceramic with εr of 32. 0. Qf of 8 240 GHz and τf of 6. 7×10 -6 ℃-1 was obtained.%采用固相合成法制备了(1-x)(Na0.3 La0.5)TiO3+xCeO2+1%CuO复合微波介质陶瓷,研究了烧结温度、微观结构和微波介电性能之间的关系.结果表明:当x=0.8,烧结温度为1 400 C时,可获得介电常数εr为35.9、品质因数Qf为11 300 GHz、谐振频率温度系数τf为98.O×10-6 ℃-1的微波介质陶瓷;通过调节体系中的x值可获得接近于0的τf,当x=0.9、烧结温度为1 400 C时,可获得εr为32.O、Qf为8 240 GHz、τf为6.7×10-6 C-1的微波介质陶瓷.

  12. 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.

  13. A surface-chemistry study of barium ferrite nanoplates with DBSa-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lisjak, Darja, E-mail: darja.lisjak@ijs.si [Jožef Stefan Institute, Ljubljana (Slovenia); Ovtar, Simona; Kovač, Janez [Jožef Stefan Institute, Ljubljana (Slovenia); Gregoratti, Luca; Aleman, Belen; Amati, Matteo [Elettra – Sincrotrone Trieste S.C.p.A. di interesse nazionale, Trieste (Italy); Fanetti, Mattia [University of Nova Gorica, Nova Gorica (Slovenia); Istituto Officina dei Materiali CNR, Area Science Park, Trieste (Italy); Makovec, Darko [Jožef Stefan Institute, Ljubljana (Slovenia)

    2014-06-01

    Barium ferrite (BaFe{sub 12}O{sub 19}) is a ferrimagnetic oxide with a high magnetocrystalline anisotropy that can be exploited in magnetically aligned ceramics or films for self-biased magnetic applications. Magnetic alignment of the films can be achieved by the directed assembly of barium ferrite nanoplates. In this investigation the nanoplates were synthesized hydrothermally and suspended in 1-butanol using dodecylbenzene sulphonic acid (DBSa) as a surfactant. They were then deposited in an electric or magnetic field on flat substrates and exhibited a significant preferential alignment in the plane of the substrate, allowing a differentiation between the analysis of their basal and side planes using scanning photoelectron microscopy with a lateral resolution down to 100 nm. The surface chemistry of the nanoplates was additionally studied with X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. For a comparison, bare barium ferrite nanoplates were also analyzed after decomposing the DBSa at 460 °C. The deviation of the surface chemistry from the stoichiometric composition was observed and the adsorption of the DBSa molecules on the nanoplates was confirmed with all three methods. Different types of bonding (physi- or chemisorption) were possible and considered with respect to the assembly of the barium ferrite nanoplates into anisotropic magnetic films.

  14. Fabrication of the Cobalt Ferrite/Lead Lanthanum Zirconate Titanate 0-3 Composite Ceramics Via Phase Boundary%相界法制备铁酸钴/锆钛酸铅镧0-3复合陶瓷

    Institute of Scientific and Technical Information of China (English)

    杨青松; 李坤; 施瑕玉; 耿志明

    2014-01-01

    The cobalt ferrite (CFO)powders were coated with zirconia via Sol-Gel methods to form core-shell thin film.The Pb(Zn0.5 W0.5 )O3-Pb(Cu0.5 W0.5 )O3 (PZW-PCW)was used as additives to low down the sintering temperature of the lead lanthanum zirconate titanate (PLZT)ceramics.The CFO/PLZT 0-3 composite ceramics were fabricated from the mixture of the coated CFO and PLZT ceramic powder by using co-firing processes.The effects of the CFO content,phase structure,micro morphology and sintering conditions on the dielectric,piezoelectric and ferroelectric properties were investigated.The X-ray and SEM diffraction results show that the ZrO2 layer can buffer the Fe3+ and Co2+ ions diffusing from CFO to PLZT during the sintering process.The composites presented the perovskite structure(PLZT)and the spinel structure(CFO)after relatively lower temperature sintering.The magneto-electric coefficient of composite ceramics(CFO weight fraction x=0.2)which were sintered at 1 050 ℃was found to be 401 mV/A at the magnetic field intensity of 334.23 A/m and frequency of 229 kHz.%通过溶胶-凝胶工艺在铁磁相CoFe2 O4(CFO)陶瓷粉体表面包覆二氧化锆,形成核壳薄层。添加钨锌酸铅-钨铜酸铅(PZW-PCW)低熔点辅助剂以降低铁电相锆钛酸铅镧(PLZT)的烧结温度。采用 CFO 和 PLZT [Pb1-1.5yLay(Zr0.58Ti0.42)1-1.25zNbzO3,y=0.06,z=0.02]粉体混合共烧工艺制备 CFO/PLZT 0-3复合多铁性材料。研究了铁磁相含量、陶瓷的晶相结构、微观形貌及烧结工艺条件对陶瓷介电、压电、铁电性能的影响。XRD、SEM分析表明,二氧化锆在高温烧结过程中可有效阻挡铁、钴离子扩散进入 PLZT相;同时相对较低温度烧结使PLZT钙钛矿相和CFO尖晶石相稳定共存。当磁场强度为334.23 A/m,频率为229 kHz时,1050℃烧结的复合陶瓷(CFO质量分数为0.20)的磁电转换系数约为401 mV/A。

  15. 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.

  16. Magneto optical trapping of Barium

    CERN Document Server

    De, S; Jungmann, K; Willmann, L

    2008-01-01

    First laser cooling and trapping of the heavy alkaline earth element barium has been achieved based on the strong 6s$^2$ $^1$S$_0$ - 6s6p $^1$P$_1$ transition for the main cooling. Due to the large branching into metastable D-states several additional laser driven transitions are required to provide a closed cooling cycle. A total efficiency of $0.4(1) \\cdot 10^{-2}$ for slowing a thermal atomic beam and capturing atoms into a magneto optical trap was obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is shortened at high laser intensities by photo ionization losses. The developed techniques will allow to extend significantly the number of elements that can be optically cooled and trapped.

  17. Radium/Barium Waste Project

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Allen K.; Ellefson, Mark D.; McDonald, Kent M.

    2015-06-25

    The treatment, shipping, and disposal of a highly radioactive radium/barium waste stream have presented a complex set of challenges requiring several years of effort. The project illustrates the difficulty and high cost of managing even small quantities of highly radioactive Resource Conservation and Recovery Act (RCRA)-regulated waste. Pacific Northwest National Laboratory (PNNL) research activities produced a Type B quantity of radium chloride low-level mixed waste (LLMW) in a number of small vials in a facility hot cell. The resulting waste management project involved a mock-up RCRA stabilization treatment, a failed in-cell treatment, a second, alternative RCRA treatment approach, coordinated regulatory variances and authorizations, alternative transportation authorizations, additional disposal facility approvals, and a final radiological stabilization process.

  18. Titan's atmosphere from DISR

    Science.gov (United States)

    West, Robert

    This abstract distills information about Titan's atmosphere described in detail in a paper by M. G. Tomasko, L. Doose, S. Engel, L. E. Dafoe, R. West, M. Lemmon, E. Karkoschka and C. See, ‘A model of Titan's aerosols based on measurements made inside the atmosphere', Planetary and Space Sciences, in press, 2008. The Descent Imager Spectral Radiometer (DISR) observed Titan's sky and surface during the descent of the Huygens Probe in January, 2005. Measurements were made over the altitude range 160 Km to the surface near latitude -10 degrees. The DISR instrument package included several components to measure the radiation state as a function of altitude. These include upward and downward-looking visible and near-infrared spectrometers covering the wavelength range 450 to 1600 nm, an ultraviolet photometer, a solar aureole camera with polarizers, and a sun sensor. Measurements were made at a variety of azimuthal angles relative to the sun azimuth. Due to unanticipated behavior of the probe (reverse spin and high-amplitude, chaotic tip and tilt) the retrieval process has required more effort than was planned and the total science return is less than expected. Nevertheless the data yielded unsurpassed and unique information which constrain the optical and physical properties of the photochemical haze aerosols and condensate particles. The principal findings are (1) between 80 Km and 160 Km the photochemical haze is well mixed with the gas with a scale height of about 65 Km, (2) between 80 Km and the surface the particle optical depth is a linear function of altitude with a break in slope near 30 Km altitude, (3) optical properties of the haze do not depend much on altitude above 80 Km although more recent work by Tomasko and colleagues suggest a gradient in the stratosphere; below 80 Km there are changes in optical behavior which suggest that condensation plays a role, (4) the data confirm previous results which proposed a particle structure of aggregates of small

  19. 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).

  20. 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).

  1. Titan Science Return Quantification

    Science.gov (United States)

    Weisbin, Charles R.; Lincoln, William

    2014-01-01

    Each proposal for a NASA mission concept includes a Science Traceability Matrix (STM), intended to show that what is being proposed would contribute to satisfying one or more of the agency's top-level science goals. But the information traditionally provided cannot be used directly to quantitatively compare anticipated science return. We added numerical elements to NASA's STM and developed a software tool to process the data. We then applied this methodology to evaluate a group of competing concepts for a proposed mission to Saturn's moon, Titan.

  2. Processing and optimization of functional ceramic coatings and inorganic nanomaterials

    Science.gov (United States)

    Nyutu, Edward Kennedy G.

    effects on the synthesis of nanocrystalline tetragonal barium titanate. The effects of microwave frequency (fixed and variable), microwave bandwidths sweep time, and aging time on the microstructure, particle sizes, phase purity, surface areas, and porosities of the as-prepared BaTiO3 were systematically investigated. The final part of the research involves a new rapid and facile synthetic route to prepare size-tunable, ultranarrow, high surface area OMS-2 nanomaterials via open-vessel microwave-assisted refluxing preparations without employing templates or surfactants. The particle size control is achieved by varying the concentration or type of non-aqueous co-solvent. The structural, textural, and catalytic application properties of the prepared nanomaterials are investigated.

  3. Sintering and foaming of barium silicate glass powder compacts

    Science.gov (United States)

    Mueller, Ralf; Reinsch, Stefan; Agea-Blanco, Boris

    2016-10-01

    The manufacture of sintered glasses and glass-ceramics, glass matrix composites and glass-bounded ceramics or pastes is often affected by gas bubble formation. Against this background, we studied sintering and foaming of barium silicate glass powders used as SOFC sealants using different powder milling procedures. Sintering was measured by means of heating microscopy backed up by XPD, DTA, Vacuum Hot Extraction (VHE) and optical and electron microscopy. Foaming increased significantly as milling progressed. For moderately milled glass powders, subsequent storage in air could also promote foaming. Although the powder compacts were uniaxially pressed and sintered in air, the milling atmosphere sig¬ni¬ficantly affected foaming. The strength of this effect increased in the order Ar ? N2 encapsulated CO2, even for powders milled in Ar and N2. Results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. Foaming could be substantially reduced by milling in water and 10 wt% HCl.

  4. Sintering and foaming of barium silicate glass powder compacts

    Directory of Open Access Journals (Sweden)

    Ralf Mueller

    2016-10-01

    Full Text Available The manufacture of sintered glasses and glass-ceramics, glass matrix composites and glass-bounded ceramics or pastes is often affected by gas bubble formation. Against this background, we studied sintering and foaming of barium silicate glass powders used as SOFC sealants using different powder milling procedures. Sintering was measured by means of heating microscopy backed up by XPD, DTA, Vacuum Hot Extraction (VHE and optical and electron microscopy. Foaming increased significantly as milling progressed. For moderately milled glass powders, subsequent storage in air could also promote foaming. Although the powder compacts were uniaxially pressed and sintered in air, the milling atmosphere sig¬ni¬ficantly affected foaming. The strength of this effect increased in the order Ar  N2 < air < CO2. Conformingly, VHE studies revealed that the pores of foamed samples predominantly encapsulated CO2, even for powders milled in Ar and N2. Results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. Foaming could be substantially reduced by milling in water and 10 wt% HCl.

  5. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject review. DATES: Effective Date: April 9, 2010. FOR FURTHER INFORMATION CONTACT:...

  6. Liquid phase sintering of BaTiO/sub 3/ by boric oxide (B/sub 2/O/sub 3/) and lead borate (PbB/sub 2/O/sub 4/) glasses and its effect on dielectric strength and dielectric constant

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, S.K.; Sharma, M.L. (National Physical Lab., New Delhi (India))

    1989-07-01

    A systematic study on liquid phase sintering of barium titanate ceramics with low melting glasses has been done. Liquid phase sintering of barium titanate with low melting glasses has the potential of reducing the sintering temperature of barium titanate and avoiding the use of expensive metals, (Pt, Pd etc) as electrodes in multilayer capacitors. As regards the effect of this technique on dielectric properties, dielectric strengths is found to increase from and dielectric constant is found to decrease.

  7. 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.

  8. 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.

  9. On Ceramics.

    Science.gov (United States)

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  10. 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.

  11. Namibian Analogs To Titan Dunes

    Science.gov (United States)

    Wall, Stephen D.; Lopes, R.; Kirk, R.; Stofan, E.; Farr, T.; Van der Ploeg, P.; Lorenz, R.; Radebaugh, J.

    2009-09-01

    Titan's equatorial dunes, observed in Cassini SAR, have been described as longitudinal, similar to longitudinal dunes in the Namib sand sea in southern Africa. Their "Y” junctions and the way they divert around topography are used as evidence of equatorial wind flow direction. In two instances of such diversion they exhibit overlying or crosshatched patterns in two distinct directions that have been interpreted as a transition to transverse dunes. Here we describe field observations of the Namibian dunes and these comparisons, we present images of the dunes from terrestrial SAR missions, and we discuss implications to both the Titan dunes and the wind regime that created them. Selected portions of the Namibian dunes resemble Titan's dunes in peak-to-peak distance and length. They are morphologically similar to Titan, and specific superficial analogs are common, but they also differ. For example, when Titan dunes encounter topography they either terminate abruptly, "climb” the upslope, or divert around; only the latter behavior is seen in remote sensing images of Namibia. Namib linear dunes do transition to transverse as they divert, but at considerably smaller wavelength, while at Titan the wavelengths are of the same scale. Crosshatching of similar-wavelength dunes does occur in Namibia, but not near obstacles. Many additional aeolian features that are seen at Namibia such as star dunes, serpentine ridges and scours have not been detected on Titan, although they might be below the Cassini SAR's 300-m resolution. These similarities and differences allow us to explore mechanisms of Titan dune formation, in some cases giving us clues as to what larger scale evidence to look for in SAR images. Viewed at similar resolution, they provide interesting comparisons with the Titan dunes, both in likeness and differences. A part of this work was carried out at JPL under contract with NASA.

  12. Smart Energy Materials of PZT Ceramics

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Okayasu

    2017-03-01

    Full Text Available To better understand the material properties of lead zirconate titanate (PZT ceramics, the domain-switching characteristics and electric power generation characteristics have been investigated during loading and unloading by using various experimental techniques. Furthermore, the influence of oscillation condition on the electrical power generation properties of lead zirconate titanate (PZT piezoelectric ceramics has been investigated. It is found that the power generation is directly attributed to the applied load and wave mode. The voltage rises instantly to the maximum level under square-wave mode, although the voltage increases gradually under triangular-wave mode. After this initial increase, there is a rapid fall to zero, followed by generation of increasingly negative voltage as the applied load is removed for all wave modes. Variation of the electric voltage is reflected by the cyclic loading at higher loading frequencies. On the basis of the obtained experimental results for the wave modes, the electrical power generation characteristics of PZT ceramics are proposed, and the voltages generated during loading and unloading are accurately estimated. The electric generation value is decrease with increasing the cyclic number due to the material failure, e.g., domain switching and crack. The influence of domain switching on the mechanical properties PZT piezoelectric ceramics is clarified, and 90 degree domain switching occurs after the load is applied to the PZT ceramic directly. Note that, in this paper, our experimental results obtained in our previous works were introduced

  13. Co-extrusion of piezoelectric ceramic fibres

    OpenAIRE

    Ismael Michen, Marina

    2011-01-01

    The present work successfully developed a methodology for fabricating lead zirconate titanate [PZT] thin solid- and hollow-fibres by the thermoplastic co-extrusion process. The whole process chain, that includes: a) compounding, involving the mixing of ceramic powder with a thermoplastic binder, b) rheological characterizations, c) preform composite fabrication followed by co-extrusion, d) debinding and, finally, e) sintering of the body to near full density, is systematical...

  14. 3-3型与1-3型多孔锆钛酸铅陶瓷的结构和性能%Structure and Properties of 3-3 Type and 1-3 Type Porous Lead Zirconate Titanate Ceramics

    Institute of Scientific and Technical Information of China (English)

    郭瑞; 汪长安; 杨安坤

    2011-01-01

    以叔丁醇为溶剂和成孔模板,采用冷冻–干燥工艺制备1-3型多孔锆钛酸铅(lead zirconate titanate,PZT)陶瓷,采用凝胶注模工艺制备3–3型多孔PZT陶瓷,利用扫描电子显微镜和压汞仪对多孔陶瓷的形貌和孔径分布进行表征,利用阻抗分析仪测试多孔陶瓷的介电常数,利用Piezo–metersystem测量仪测试样品的压电性能。结果表明:相比于3–3型多孔PZT陶瓷,在初始浆料固含量相同的条件下,1–3型多孔PZT陶瓷具有更高的气孔率;而气孔率相当时,1–3型多孔PZT陶瓷的压电系数比3–3型样品高出20%以上,介电常数高出1倍左右,且最低的声阻抗已达到2.1×107(Pa?s)/m,明显低于3–3型样品并与生物组织和水的声阻抗值非常接近%3–3 type porous lead zirconate titanate(PZT) ceramics were prepared by a gel-casting method and 1-3 type porous PZT ceramics were prepared by a freeze casting process with tert-butyl alcohol(TBA) as solvent and template.The microstructure was determined by scanning electron microscope and the pore-size distributions were analyzed by a mercury intrusion method.The longitude piezoelectric coefficient(d33) was measured by a Piezo–Meter System and the permittivity(ε) was measured under constant(zero) stress using an impedance bridge.Compared to 3-3 type porous PZT ceramics,the 1–3 type samples had a higher porosity with the same initial solid loading of slurry.When the porosity was the same,the 1–3 type samples also had greater d33 and ε(the d33 value was 20% greater than that of the 3-3 type samples and the relative permittivity value was 100% greater than that of the 3-3 type samples).The acoustic impendence of 1–3 type samples,which reached 2.1 × 107(Pa?s)/m that matched well with the water or human tissue,was lower than that of 3-3 type samples

  15. 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.

  16. Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

    Science.gov (United States)

    Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

    2013-01-01

    Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping.

  17. 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.

  18. Abundance analysis of Barium stars

    Institute of Scientific and Technical Information of China (English)

    Guo-Qing Liu; Yan-Chun Liang; Li-Cai Deng

    2009-01-01

    We obtain the chemical abundances of six barium stars and two CH subgiant stars based on the high signal-to-noise ratio and high resolution Echelle spectra. The neu- tron capture process elements Y, Zr, Ba, La and Eu show obvious overabundances relative to the Sun, for example, their [Ba/Fe] values are from 0.45 to 1.27. Other elements, in- cluding Na, Mg, A1, Si, Ca, Sc, Ti, V, Cr, Mn and Ni, show comparable abundances to the Solar ones, and their [Fe/H] covers a range from -0.40 to 0.21, which means they belong to the Galactic disk. The predictions of the theoretical model of wind accretion for bi- nary systems can explain the observed abundance patterns of the neutron capture process elements in these stars, which means that their overabundant heavy-elements could be caused by accreting the ejecta of AGB stars, the progenitors of present-day white dwarf companions in binary systems.

  19. 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

  20. 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.

  1. 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

  2. Study on the Rare Earth Element and Lead Titanate Doping in Lead Magnesium Niobate Ceramics%铌镁酸铅陶瓷的稀土元素及钛酸铅互掺改性研究

    Institute of Scientific and Technical Information of China (English)

    李惠琴; 刘敬松

    2012-01-01

    本文采用了铌铁矿法,研究了稀土元素及钛酸铅(PT)的掺入对铌镁酸铅(PMN)铁电陶瓷的介电性能及拉曼行为的影响.分别掺入Y2O3 、Sin2O3、La2O3稀土氧化物后,PMN的介电常数峰值(εm)有所下降,而掺人PT后εm有所上升.稀土元素的掺人使相转变温度(Tm)朝远离居里点的低温方向移动,室温下的介电损耗值减小,介电常数频率稳定性得到增强.PT的掺入使Tm朝接近居里点的高温方向移动.拉曼光谱研究表明稀土元素、PT的掺人影响了PMN陶瓷的B位有序度,导致其介电性变化.%The columbite route was used in this work, and the influences of the addition of rare earth elements and PbTiO3 (PT) on the dielectric properties and Raman behavior of Pb( Mg1/3Nb2/3)O3 (PMN) ceramics were investigated. When Y2O3, Sm2O3 and La2O3 were added into PMN, the maximum of dielectric constant (εm) decreased. While PT was added, εm increased. The doping of rare earth elements resulted that the temperature of phase transition ( Tm) moves to lower temperature far away the Curie point and dissipation factor at room temperature decreased, and the frequency dependence of dielectric constant get stabilized. The addition of PT moved Tm to higher temperature near the Curie point. The Raman investigation on the influence of rare earth elements and PT addition revealed that the change of chemical degree of B-site resulted in the dielectric property change.

  3. 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.

  4. Maximising electro-mechanical response by minimising grain-scale strain heterogeneity in phase-change actuator ceramics

    DEFF Research Database (Denmark)

    Oddershede, Jette; Hossain, Mohammad Jahangir; Daniels, John E.

    2016-01-01

    Phase-change actuator ceramics directly couple electrical and mechanical energies through an electric-field-induced phase transformation. These materials are promising for the replacement of the most common electro-mechanical ceramic, lead zirconate titanate, which has environmental concerns. Her...

  5. Proton conducting ceramic membranes for hydrogen separation

    Science.gov (United States)

    Elangovan, S.; Nair, Balakrishnan G.; Small, Troy; Heck, Brian

    2011-09-06

    A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

  6. Role of Mn doping for obtaining of hexagonal phase in Ba0.98Zn0.02TiO3 ceramics

    Science.gov (United States)

    Das, S. K.; Roul, B. K.

    2016-08-01

    This paper reports the observation of hexagonal phase of barium titanate by Mn doping and its effect on dielectric and magnetic properties. Ceramic samples of Ba0.98Zn0.02Ti1-xMnxO3 (where, x= 0.04, 0.06 and 0.08) were prepared by traditional solid-state reaction route. The hexagonal phase is stabilized in the composition Ba0.98Zn0.02Ti0.92Mn0.08O3 and a very feeble M-H loop is also observed in that composition. This induced magnetism is expected due to the exchange interactions between magnetic polarons formed by oxygen vacancies with Mn ions. The dielectric constant as well as the ferroelectric to paraelectric transition temperature is systematically decreased with increasing of Mn doping concentration. Further to that, the temperature dependent dielectric constant curve is also broadened at transition temperature with increasing of Mn concentration. However, the ferroelectric to paraelectric transition temperature is well above room temperature.

  7. Defect Chemistry and Microstructure of Complex Perovskite Barium Zinc Niobate

    Science.gov (United States)

    Peng, Ping

    1991-02-01

    This dissertation presents a systematic study of the characterization of the phase transitions, microstructures, defects and transport properties of undoped and doped complex perovskite barium zinc niobate (BZN). Complex perovskite BZN is a paraelectric material while its parent material barium titanate is ferroelectric. With codoping of (Zn + 2Nb) into Ti site, BaTiO_3 shows three distinguished features. First, the Curie temperature is lowered; second, the three phase transitions (cubic-tetragonal-orthorhombic-rhombohedral) coalesce; and lastly, the transition becomes diffuse showing a typical 2nd order phase transition compared with 1st order in undoped BaTiO_3. Complex microchemical ordering is another characteristic of BZN. Stoichiometric BZN shows a mixture of two types of ordering schemes. 1:1, 1:2 ordered microdomains and the disordered matrix co-exist. The 1:1 type ordering involves an internal charge imbalance which inhibits the growth of 1:1 type of ordered microdomains. The 1:2 type ordering is consistent with the chemical composition of BZN. These ordering patterns can be modified by either adjustment of the Zn/Nb ratio or by doping. The defect structure of the stoichiometric BZN is closely related to that of BaTiO_3. Stoichiometric BZN is an insulator with wide band gap (~ 3.70 eV). Undoped BZN has a high oxygen vacancy concentration which comes from three possible sources, such as unavoidable acceptor impurities, due to their natural abundance, Zn/Nb ratio uncertainty due to processing limitations, and high temperature ZnO loss due to sintering process. The oxygen vacancy concentration for undoped BZN lays in the neighborhood of 1500 ppm (atm.). The compensation defects for various dopants have also been identified. Both electrons and holes conduct by a small polaron mechanism. Various thermodynamic parameters, such as enthalpies of oxidation and reduction, mass action constants for intrinsic electronic disorder, oxidation and reduction have been

  8. Thermal Conductivity of Composites of Beryllia and Lithium Titanate

    Science.gov (United States)

    Rath, B. N.; Ghanwat, S. J.; Kaity, Santu; Danani, Chandan; Kulkarni, R. V.; Alur, V. D.; Sathiyamoorthy, D.; Anantharaman, S.

    2013-11-01

    The International Thermonuclear Experimental Reactor (ITER) is designed to demonstrate the scientific and technological feasibility of fusion power for energy purposes. Wide varieties of solid breeders and multiplier materials have been proposed for fusion blankets. Beryllium and lithium titanate (Li2TiO3) have been accepted as neutron multiplier and breeder materials, respectively. However, swelling of beryllium due to helium and tritium permeation through metallic beryllium and low thermal conductivity of lithium titanate have caused serious limitations when ITER is in the demo version. It has been well established that BeO due its highest thermal conductivity among the known ceramics, low neutron absorption cross section, and high neutron reflection cross section is a good neutron multiplier. In the present investigation, a novel ceramic single compound of BeO-Li2TiO3 was synthesized, keeping the BeO content to Li2TiO3 in the volume ratio of 80:20, 75:25, 65:35, and 55:45 with the aim of maintaining the tritium breeding ratio as more than one, and characterized for phases present by x-ray diffraction and scanning electron microscopy.

  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. Improved spectrophotometric analysis of barium styphnate

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N E; Blasi, J A

    1983-01-01

    A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

  11. Zirconium titanate: stability and thermal expansion; Titanato de circonio: estabilidad termodinamica y expansion termica

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Lopez, E.; Moreno, R.; Baudin, C.

    2011-07-01

    Zirconium titanate is a well known compound in the field of electro ceramics, although it has also been used in catalyst and sensors applications. The crystallographic thermal expansion anisotropy of this compound makes it a potential candidate as constituent of structural components. In general, to assure the structural integrity and microstructural homogeneity of a ceramic piece, relatively low cooling rates from the fabrication temperature are required. This requirement is essential for zirconium titanate because thermal expansion as well as phase distribution is affected by small variations in the composition and cooling rate. This work reviews the available data on the phase equilibrium relationships in the systems ZrO{sub 2}-TiO{sub 2} and ZrO{sub 2}-TiO{sub 2}-Y{sub 2}O{sub 3}. The main discrepancies as well as the possible origins of them are discussed. Additionally, the crystallographic thermal expansion data in the current literature are reviewed. (Author) 56 refs.

  12. Ceramic Processing

    Energy Technology Data Exchange (ETDEWEB)

    EWSUK,KEVIN G.

    1999-11-24

    Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.

  13. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  14. 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...

  15. 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...

  16. Residual strain scanning of alumina-based ceramic composites by neutron diffraction

    Science.gov (United States)

    Ruiz-Hervias, J.; Bruno, G.; Bueno, S.; Gurauskis, J.; Baudín, C.; Fan, K. Y.

    2014-11-01

    Residual strain profiles were measured by neutron diffraction in alumina-aluminum titanate ceramic composites sintered at two different temperatures, namely 1450 and 1550°C. The results show that irrespective of the direction and the sintering temperature, the obtained profiles are almost flat, with very similar results for both temperatures. In addition, the results demonstrate that the alumina is in compression whereas the aluminium titanate is subjected to tensile residual stresses.

  17. Ferroelastic contribution to the piezoelectric response in lead zirconate titanate by in situ stroboscopic neutron diffraction

    Science.gov (United States)

    Jones, Jacob L.; Hoffman, Mark; Daniels, John E.; Studer, Andrew J.

    2006-11-01

    Ferroelastic domain switching during dynamic actuation is measured in situ for a piezoelectric lead zirconate titanate (PZT) ceramic utilizing a new capability developed on The Australian Strain Scanner (TASS) at ANSTO. Diffraction patterns are obtained as a function of time during a 1 Hz cycle. The change in the 0 0 2 and 2 0 0 diffraction intensities indicates there is ferroelastic domain switching at sub-coercive (weak) fields.

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. Charged particles in Titan's ionosphere

    Science.gov (United States)

    Tripathi, Sachchida

    2010-05-01

    Charged particles in Titan's ionosphere Marykutty Michael1, Sachchida Nand Tripathi1,2,3, Pratima Arya1 1Indian Institute of Technology Kanpur 2Oak Ridge Associated Universities 3NASA Goddard Space Flight Center Observations by two instruments onboard the Cassini spacecraft, Ion Neutral Mass Spectrometer (INMS) and CAssini Plasma Spectrometer (CAPS), revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units at altitudes of 950 - 1400 km in the atmosphere of Titan (Waite et al., 2007; Crary et al., 2009). Though these particles were believed to be molecules, they are most likely aerosols formed by the clumping of smaller molecules (Waite et al., 2009). These particles were estimated to have a density of 10-3 kg m-3 and a size of up to 256 nm. The existence of very heavy ions has also been observed by the CAPS components with a mass by charge ratio of up to 10000 (Coates et al., 2007, 2009; Sittler et al., 2009). The goal of this paper is to find out whether the so called heavy ions (or charged particles) are generated by the charge transfer of ions and electrons to the particles. The charging of these particles has been studied by using the charge balance equations that include positive ions, negative ions, electrons, neutral and charged particles. Information on the most abundant ion clusters are obtained from Vuitton et al., (2009) and Wilson and Atreya, (2004). Mass by charge ratio thus calculated will be compared with those observed by Coates et al. (2007). References: Coates AJ, et al., Discovery of heavy negative ions in Titan's ionosphere, Geophys. Res. Lett., 34:L22103, 2007. Coates AJ, et al., Heavy negative ions in titan's ionosphere: altitude and latitude dependence. Planet. Space Sci., doi:10.1016/j.pss.2009.05.009, 2009. Crary F.J., et al., Heavy ions, temperatures and winds in titan's ionosphere: Combined cassini caps and inms observations. Planet. Space Sci., doi:10.1016/j.pss.2009.09.006, 2009

  3. Barium Ferrite Films Grown by Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Smithers, M.A.; Roesthuis, F.J.G.

    1998-01-01

    Pulsed laser ablation (PLA) has been used to grow barium ferrite films on Al2O3 single crystal substrates. When deposition occurs in an oxidising atmosphere at high temperatures, the films are single BaFe12O19 phase, very well oriented with (001) texture, and exhibit a large perpendicular magnetic a

  4. Ceramic Methyltrioxorhenium

    CERN Document Server

    Herrmann, R; Eickerling, G; Helbig, C; Hauf, C; Miller, R; Mayr, F; Krug von Nidda, H A; Scheidt, E W; Scherer, W; Herrmann, Rudolf; Troester, Klaus; Eickerling, Georg; Helbig, Christian; Hauf, Christoph; Miller, Robert; Mayr, Franz; Nidda, Hans-Albrecht Krug von; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang

    2006-01-01

    The metal oxide polymeric methyltrioxorhenium [(CH3)xReO3] is an unique epresentative of a layered inherent conducting organometallic polymer which adopts the structural motifs of classical perovskites in two dimensions (2D) in form of methyl-deficient, corner-sharing ReO5(CH3) octahedra. In order to improve the characteristics of polymeric methyltrioxorhenium with respect to its physical properties and potential usage as an inherentconducting polymer we tried to optimise the synthetic routes of polymeric modifications of 1 to obtain a sintered ceramic material, denoted ceramic MTO. Ceramic MTO formed in a solvent-free synthesis via auto-polymerisation and subsequent sintering processing displays clearly different mechanical and physical properties from polymeric MTO synthesised in aqueous solution. Ceramic MTO is shown to display activated Re-C and Re=O bonds relative to MTO. These electronic and structural characteristics of ceramic MTO are also reflected by a different chemical reactivity compared with its...

  5. 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.

  6. Dielectric and Impedance Spectroscopy of Barium Bismuth Vanadate Ferroelectrics

    Science.gov (United States)

    Sutar, B. C.; Choudhary, R. N. P.; Das, Piyush R.

    2014-07-01

    Structural, micro-structural and electrical properties of barium bismuth vanadate Ba(Bi0.5V0.5)O3 ceramics were investigated. X-ray diffraction (XRD) analysis of the prepared material confirmed the formation of the compound with monoclinic crystal system. Scanning electron microscopy (SEM) of the compound exhibits well-defined grains that are uniformly distributed throughout the surface of the sample. Dielectric properties of the compound were studied as a function of temperature at different frequencies. An observation of dielectric anomaly at 295 °C is due to ferroelectric phase transition that was later confirmed by the appearance of hysteresis loop. Detailed studies of complex impedance spectroscopy have provided a better understanding of the relaxation process and correlations between the microstructure-electrical properties of the materials. The nature of frequency dependence of ac conductivity obeys the Debye power law. The dc conductivity, calculated from the ac conductivity spectrum, shows the negative temperature coefficient of resistance behavior similar to that of a semiconductor.

  7. Synthesis, characterization and electric evaluation of barium zirconate doped with trivalent lanthanides; Sintesis, caracterizacion y evaluacion electrica de circonatos de bario dopados con lantanidos trivalentes

    Energy Technology Data Exchange (ETDEWEB)

    Gerena, O. A.; Carda, J. B.; Beltran, H.; Cordoncillo, E.; Valencia, J. S.

    2014-04-01

    Barium zirconate is an oxidic material having perovskite structure that exhibits high chemical stability in both oxidizing and reducing environments, such as in the presence of water and carbon dioxide, its conductivity has led to consider it as a electrolyte for solid oxide fuel cell finding good results, with the limitation of operating at temperatures above 800 degree centigrade. Several researchers have proposed that it is possible to improve their electrical conductivity by changes in chemical composition, particularly for doping with trivalent cations that replace the zirconium in B site of perovskite. In this study, barium zirconate was synthesized by the amorphous citrate method to examine the possibility of obtaining in more favorable conditions than those made by the conventional method of synthesis (ceramic method or solid state reaction) conditions are synthesized. Barium zirconate doped with europium, gadolinium, holmium, lanthanum, neodymium and praseodymium was prepared, the present phase identified cation was verified by X-ray diffraction (XRD), the electrical properties were examined by impedance spectroscopy (IS) at temperatures between 480 and 680 degree centigrade in order to evaluate its potential use as a fuel cell electrolyte in solid oxide. The contributions of this research has focused on the synthesis method, in the production of ceramic powders of barium zirconate at temperatures lower than those required by the ceramic method, in obtaining chemical, structural, morphological and electrical information of material synthesized. The desired phase synthesis conditions set found, also, a significant increase is seen in the solid conductivity of doped lanthanum, holmium and europium zirconate of barium in relation to the material without doping. (Author)

  8. 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.

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

    DEFF Research Database (Denmark)

    Majkut, Marta

    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...... diffraction patterns is minimized to refine domain-scale orientations and lattice parameters. We present the results of refinement for a bulk grain in which the domains are found to be misoriented from perfect crystallographic twins by 0.1-0.3°, suggesting a strained microstructure. The data set was collected...

  10. 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.

  11. Piezoelectric paper fabricated via nanostructured barium titanate functionalization of wood cellulose fibers.

    Science.gov (United States)

    Mahadeva, Suresha K; Walus, Konrad; Stoeber, Boris

    2014-05-28

    We have successfully developed hybrid piezoelectric paper through fiber functionalization that involves anchoring nanostructured BaTiO3 into a stable matrix with wood cellulose fibers prior to the process of making paper sheets. This is realized by alternating immersion of wood fibers in a solution of poly(diallyldimethylammonium chloride) PDDA (+), followed by poly(sodium 4-styrenesulfonate) PSS (-), and once again in PDDA (+), resulting in the creation of a positively charged surface on the wood fibers. The treated wood fibers are then immersed in a BaTiO3 suspension, resulting in the attachment of BaTiO3 nanoparticles to the wood fibers due to a strong electrostatic interaction. Zeta potential measurements, X-ray diffraction, and microscopic and spectroscopic analysis imply successful functionalization of wood fibers with BaTiO3 nanoparticles without altering the hydrogen bonding and crystal structure of the wood fibers. The paper has the largest piezoelectric coefficient, d33 = 4.8 ± 0.4 pC N(-1), at the highest nanoparticle loading of 48 wt % BaTiO3. This newly developed piezoelectric hybrid paper is promising as a low-cost substrate to build sensing devices.

  12. 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.)

  13. 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.

  14. 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.

  15. Thin film barium strontium titanate capacitors for tunable RF front-end applications

    NARCIS (Netherlands)

    Tiggelman, Markus Petrus Josephus

    2009-01-01

    In this thesis, the results of intensive electrical characterization, modeling and the design of hardware with thin film tunable capacitors, i.e., dielectric varactors, has been presented and discussed. Especially the quality factor Q and the tuning ratio of the tunable capacitors have been studied

  16. 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.

  17. 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.

  18. Radiological response of ceramic and polymeric devices for breast brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Batista Nogueira, Luciana, E-mail: lucibn19@yahoo.com.br [Departamento de Propedeutica Complementar, Faculdade de Medicina, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha 31270901, BH/MG (Brazil); Passos Ribeiro de Campos, Tarcisio, E-mail: campos@nuclear.ufmg.br [Departamento de Engenharia Nuclear, Programa de Pos Graduacao em Ciencias e Tecnicas Nucleares, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Pampulha 31270901, BH/MG (Brazil)

    2012-04-15

    In the present study, the radiological visibility of ceramic and polymeric devices implanted in breast phantom was investigated for future applications in brachytherapy. The main goal was to determine the radiological viability of ceramic and polymeric devices in vitro by performing simple radiological diagnostic methods such as conventional X-ray analysis and mammography due to its easy access to the population. The radiological response of ceramic and polymeric devices implanted in breast phantom was determined using conventional X-ray, mammography and CT analysis. - Highlights: Black-Right-Pointing-Pointer Radiological visibility of ceramic and polymeric devices implanted in breast phantom. Black-Right-Pointing-Pointer The barium incorporation in the seed improves the radiological contrast. Black-Right-Pointing-Pointer Radiological monitoring shows the position, orientation and degradation of devices. Black-Right-Pointing-Pointer Simple radiological methods such as X-ray and mammography were used for radiological monitoring.

  19. Engineering ceramics

    CERN Document Server

    Bengisu, Murat

    2001-01-01

    This is a comprehensive book applying especially to junior and senior engineering students pursuing Materials Science/ Engineering, Ceramic Engineering and Mechanical Engineering degrees. It is also a reference book for other disciplines such as Chemical Engineering, Biomedical Engineering, Nuclear Engineering and Environmental Engineering. Important properties of most engineering ceramics are given in detailed tables. Many current and possible applications of engineering ceramics are described, which can be used as a guide for materials selection and for potential future research. While covering all relevant information regarding raw materials, processing properties, characterization and applications of engineering ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  20. Kinetic and structural analyses for the formation of anatase nanocrystals in barium titanoborate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jong Youn; Sung, Yun-Mo, E-mail: ymsung@korea.ac.kr

    2015-10-25

    Transparent barium titanoborate glass-ceramics bearing TiO{sub 2} (anantase) nanocrystals were prepared by the conventional melt-quenching and subsequent heat treatment of 35BaO–xTiO{sub 2}–110B{sub 2}O{sub 3} (in mol) (x = 20, 25, and 30) glasses. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results clearly reveal the formation of highly-crystalline anatase nanocrystals in glass matrices. The average crystal size ranges from ∼10 to 20 nm according to TiO{sub 2} contents. Non-isothermal kinetic analyses were performed to understand the crystallization behavior of each glass using differential scanning calorimetry (DSC) scan curves. With the increase of TiO{sub 2} contents in the glass, the crystallization peak temperature of TiO{sub 2} decreases, while the activation energy for crystallization increases. We propose a possible mechanism for the formation of TiO{sub 2} nanocrystals based upon kinetic analysis results and structural changes in barium titanoborate glass matrices according to TiO{sub 2} contents. The nanocrystalline glass-ceramics show ∼60–75% visible light transmittance and sharp UV-light absorption edges at ∼387 nm, corresponding to the energy band gap of anatase (3.2 eV). They show apparent photocatalytic properties and ∼70% of methylene blue solution was decomposed within 180 min. - Highlights: • The first report on the TiO{sub 2} nanocrystal formation mechanism in borate glasses. • TiO{sub 2} seems not to be involved in the borate glass network forming. • Crystallization temperature increases and activation E decreases with TiO{sub 2} content. • Increasing number of non-bridging oxygens affect the crystallization kinetics. • UV-light blocking and photocatalytic properties were identified for glass-ceramics.

  1. 77 FR 59690 - Titan Resources International, Corp.; Order of Suspension of Trading

    Science.gov (United States)

    2012-09-28

    ... COMMISSION Titan Resources International, Corp.; Order of Suspension of Trading September 26, 2012. It... concerning the securities of Titan Resources International, Corp. (``Titan''). Titan is a Wyoming corporation... releases and other public statements concerning Titan's business operations and financial condition....

  2. A hybrid phenomenological model for ferroelectroelastic ceramics. Part II: Morphotropic PZT ceramics

    Science.gov (United States)

    Stark, S.; Neumeister, P.; Balke, H.

    2016-10-01

    In this part II of a two part series, the rate-independent hybrid phenomenological constitutive model introduced in part I is modified to account for the material behavior of morphotropic lead zirconate titanate ceramics (PZT ceramics). The modifications are based on a discussion of the available literature results regarding the micro-structure of these materials. In particular, a monoclinic phase and a highly simplified representation of the hierarchical structure of micro-domains and nano-domains observed experimentally are incorporated into the model. It is shown that experimental data for the commercially available morphotropic PZT material PIC151 (PI Ceramic GmbH, Lederhose, Germany) can be reproduced and predicted based on the modified hybrid model.

  3. The determination of major and some minor constituents in lead zirconate-titanate compositions by x-ray fluorescence and atomic absorption spectrometry

    NARCIS (Netherlands)

    Willigen, van J.H.H.G.; Kruidhof, H.; Dahmen, E.A.M.F.

    1972-01-01

    An accurate X-ray fluorescence spectrometric method is described for the determination of lead, zirconium and titanium in lead zirconate-titanate ceramics. Careful matching of samples and standards by a borax fusion method resulted in a relative standard deviation of about 0.2% for the major constit

  4. 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...

  5. Analysis of 26 Barium Stars I. Abundances

    CERN Document Server

    Allen, D M; Allen, Dinah M.; Barbuy, Beatriz

    2006-01-01

    We present a detailed analysis of 26 barium stars, including dwarf barium stars, providing their atmospheric parameters (Teff, log g, [Fe/H], vt) and elemental abundances. We aim at deriving gravities and luminosity classes of the sample stars, in particular to confirm the existence of dwarf barium stars. Accurate abundances of chemical elements were derived. Abundance ratios between nucleosynthetic processes, by using Eu and Ba as representatives of the r- and s-processes are presented. High-resolution spectra with the FEROS spectrograph at the ESO-1.5m Telescope, and photometric data with Fotrap at the Zeiss telescope at the LNA were obtained. The atmospheric parameters were derived in an iterative way, with temperatures obtained from colour-temperature calibrations. The abundances were derived using spectrum synthesis for Li, Na, Al, alpha-, iron peak, s- and r-elements atomic lines, and C and N molecular lines. Atmospheric parameters in the range 4300 < Teff < 6500, -1.2 < [Fe/H] < 0.0 and 1.4...

  6. Structural Ceramics Database

    Science.gov (United States)

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  7. 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.

  8. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    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.

  9. Thermochemical hydrogen production via a cycle using barium and sulfur: reaction between barium sulfide and water

    Energy Technology Data Exchange (ETDEWEB)

    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 to 866/sup 0/C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. The rate of formation of hydrogen can be expressed as: RH2 = 1.07 x 10/sup -2/ exp (-3180/RT) (mol H/sub 2//mol BaS s). Hydrogen sulfide was produced during the initial period of reaction and the quantity of hydrogen sulfide formed during this period decreased as the temperature of reaction was increased.

  10. Order-disorder correlation on local structure and photo-electrical properties of La3+ ion modified BZT ceramics

    Science.gov (United States)

    Ghosh, S. K.; Ganguly, M.; Rout, S. K.; Sinha, T. P.

    2015-04-01

    Rare earth lanthanum (La) doped barium zirconate titanate, Ba1 - x La2 x/3Zr0.3Ti0.7O3 (BLZT) ceramics, with x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10 were prepared using solid state reaction route. Structural characterizations of the materials were done by using X-ray diffraction and Raman spectroscopy. The Rietveld refinement technique employed to investigate the details of the crystal structure revealed a single phase cubic perovskite structure for all the compositions, belonging to the space group Pm-3m. Raman spectroscopy was used to probe the order-disorder correlation in local symmetry and it was verified that the presence of disorder in cubic structure is increased due to La3+ ion substitution at A-site. In addition, the signature of relaxor behavior and diffuse types of phase transition can be detected by monitoring the relative intensity of Raman features. Room temperature photo-electronic properties were investigated by using ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. Heterovalent doping (La3+) is accompanied by creation of ionic defects to maintain the charge neutrality; as a result the intermediate energy levels are formed within the band gap. These intermediate energy levels play a significant role in electronic band transitions in higher La concentration, x ≥ 0.08; enhancing the self-trapping mechanism leads to slightly decreasing in band gap values and shifting the PL emission spectra towards violet-blue regions. The temperature dependence of the dielectric constant was investigated and relaxor type of phase transition was observed in the material. The degree of relaxor behavior was enhanced with increase in La3+ ion concentration.

  11. 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...

  12. 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.

  13. Potassium Sodium Niobate-Based Lead-Free Piezoelectric Multilayer Ceramics Co-Fired with Nickel Electrodes

    Directory of Open Access Journals (Sweden)

    Shinichiro Kawada

    2015-11-01

    Full Text Available Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main problems is fabricating a multilayer structure, and one solution attracting growing interest is the use of lead-free multilayer piezoelectric ceramics. The paper reviews work that has been done by the authors on lead-free alkali niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes. However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free alkali niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain (Smax/Emax of a representative alkali niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where Smax denotes the maximum strain and Emax denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. In the paper, the compositional design and process used to co-fire lead-free ceramics with nickel inner electrodes are introduced, and their piezoelectric properties and reliabilities are shown. Recent advances are introduced, and future development is discussed.

  14. 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.

  15. JPRS Report, Science & Technology, Japan, Fine Ceramics Industry Basic Issues Forum

    Science.gov (United States)

    2007-11-02

    substrate material, and phosphates for use as bioceramic materials; and such structural materials as zirconia, silicon 26 carbide, and silicon nitride. R&D...communications equipment, and for bioceramics materials in the medical equipment field. And while R&D has yet to get underway, it is hoped that fine ceramics...Lion Corporation Bioceramic dental crowns Ishihara Pharmaceuticals Aluminum titanate machinable

  16. Current Issues with Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.

    2004-01-01

    The environmental barrier coating (EBC) for SiC/SiC ceramic matrix composites and Si3N4 ceramics is an emerging field as the application of silicon-based ceramics in the gas turbine engine hot section is on the horizon, both for aero and industrial gas turbines. EBC is an enabling technology for silicon-based ceramics because these materials without an EBC cannot be used in combustion environments due to rapid surface recession. Significant progress in EBC development has been made during the last decade through various government-sponsored programs. Current EBCs are based on silicon, mullite (3Al2O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit temperature capability of current EBCs to about 1350 C for long-term applications. There is a need for higher temperature EBCs as the temperature capability of silicon-based ceramics continue to increase. Therefore, research is underway to develop EBCs with improved temperature capability compared to current EBCs. The current status and issues with the advanced EBC development efforts will be discussed.

  17. Chemical Composition of Ceramic Tile Glazes

    Science.gov (United States)

    Anufrik, S. S.; Kurian, N. N.; Zhukova, I. I.; Znosko, K. F.; Belkov, M. V.

    2016-11-01

    We have carried out laser emission and x-ray fluorescence spectral analysis of glaze before and after its application to ceramic tile produced by Keramin JSC (Belarus). We have studied the internal microstructure of the ceramic samples. It was established that on the surface and within the bulk interior of all the samples, there are micropores of sizes ranging from a few micrometers to tens of micrometers and microcracks as long as several hundred micrometers. The presence of micropores on the surface of the ceramic tile leads to an increase in the water absorption level and a decrease in frost resistance. It was found that a decrease in the surface tension of ceramic tile coatings is promoted by substitution of sodium by potassium, silica by boric anhydride, magnesium and barium by calcium, CaO by sodium oxide, and SiO2 by chromium oxide. We carried out a comparative analysis of the chemical composition of glaze samples using S4 Pioneer and ElvaX x-ray fluorescence spectrometers and also an LIBS laser emission analyzer.

  18. Curie temperature and magnetic properties of aluminum doped barium ferrite particles prepared by ball mill method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Daming [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); College of Materials and Chemical Engineering, Hainan University, Haikou 570228, Hainan (China); Harward, Ian; Baptist, Joshua; Goldman, Sara; Celinski, Zbigniew [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States)

    2015-12-01

    Barium ferrite has attracted considerable interest in the fields of permanent magnets and perpendicular magnetic recording due to its strong uniaxial anisotropy and high Curie temperature (T{sub c}). We prepared aluminum doped barium ferrite ceramics (BaAl{sub x}Fe{sub 12−x}O{sub 19}, 0≤x≤6) by the ball mill method. The powder was milled for 96 h, and after forming pellets, annealed for 48 h in air at 1000 °C. The X-ray diffraction (XRD) data show that there are only single hexagonal phases in the samples without any impurity phase. The crystal lattice constants, a and c, were calculated by Cohen's method. Both a and c decrease with increasing x, ranging from 0.588 nm and 2.318 nm to 0.573 nm and 2.294 nm, respectively. A Vibrating Sample Magnetometer (VSM) and Superconducting Quantum Interference Device (SQUID) were used to investigate T{sub c} and magnetic properties of BaFe{sub 12−x}Al{sub x}O{sub 19}. It is found that T{sub c} decreases with increasing x, from 425 °C to 298 °C. It is also found that the saturated magnetization (4πM{sub s}) decreases with increasing x, while the coercivity (H{sub c}) increases with the increase in x. The anisotropy field was also determined from the SQUID measurement. - Highlights: • The Curie temperature and magnetic properties of aluminum doped barium ferrite particles were studied systemically. • The relation between 4πM{sub s} and composition x at 50 K (both experimental value and theoretical calculation) was revealed. • Occupation number for spin up and spin down as a function of temperature was shown. • The relation between 4πM{sub s} and composition x from 50 K to room temperature was revealed.

  19. 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.

  20. [Silica, aluminum, iron, sulfur, and barium in a urinary calculus].

    Science.gov (United States)

    Rodríguez-Miñón Cifuentes, J L; Salvador, E; Bellanato, J; Medina, J A

    1994-05-01

    Presentation of the analytical results by Sweep Microscopy of a small papillary calculus spontaneously eliminated after a nephritic colic. The main component is monohydrate calcium oxalate. When the stone core was analyzed with EDAX, silica, aluminium, iron, sulphur and barium were detected. The origin of these elements is discussed and the presence of barium emphasized as exceptional.

  1. Scattering lengths of calcium and barium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dammalapati, U.; Willmann, L.; Knoop, S. [Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)

    2011-11-15

    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 {sup 40}Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes.

  2. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  3. Curie temperature and magnetic properties of aluminum doped barium ferrite particles prepared by ball mill method

    Science.gov (United States)

    Chen, Daming; Harward, Ian; Baptist, Joshua; Goldman, Sara; Celinski, Zbigniew

    2015-12-01

    Barium ferrite has attracted considerable interest in the fields of permanent magnets and perpendicular magnetic recording due to its strong uniaxial anisotropy and high Curie temperature (Tc). We prepared aluminum doped barium ferrite ceramics (BaAlxFe12-xO19, 0≤x≤6) by the ball mill method. The powder was milled for 96 h, and after forming pellets, annealed for 48 h in air at 1000 °C. The X-ray diffraction (XRD) data show that there are only single hexagonal phases in the samples without any impurity phase. The crystal lattice constants, a and c, were calculated by Cohen's method. Both a and c decrease with increasing x, ranging from 0.588 nm and 2.318 nm to 0.573 nm and 2.294 nm, respectively. A Vibrating Sample Magnetometer (VSM) and Superconducting Quantum Interference Device (SQUID) were used to investigate Tc and magnetic properties of BaFe12-xAlxO19. It is found that Tc decreases with increasing x, from 425 °C to 298 °C. It is also found that the saturated magnetization (4πMs) decreases with increasing x, while the coercivity (Hc) increases with the increase in x. The anisotropy field was also determined from the SQUID measurement.

  4. Analysis of isothermal sintering of zinc-titanate doped with MgO

    Directory of Open Access Journals (Sweden)

    Obradović N.

    2007-01-01

    Full Text Available The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5% were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate.

  5. Size and shape of Saturn's moon Titan

    Science.gov (United States)

    Zebker, Howard A.; Stiles, Bryan; Hensley, Scott; Lorenz, Ralph; Kirk, Randolph L.; Lunine, Jonathan

    2009-01-01

    Cassini observations show that Saturn's moon Titan is slightly oblate. A fourth-order spherical harmonic expansion yields north polar, south polar, and mean equatorial radii of 2574.32 ± 0.05 kilometers (km), 2574.36 ± 0.03 km, and 2574.91 ± 0.11 km, respectively; its mean radius is 2574.73 ± 0.09 km. Titan's shape approximates a hydrostatic, synchronously rotating triaxial ellipsoid but is best fit by such a body orbiting closer to Saturn than Titan presently does. Titan's lack of high relief implies that most—but not all—of the surface features observed with the Cassini imaging subsystem and synthetic aperture radar are uncorrelated with topography and elevation. Titan's depressed polar radii suggest that a constant geopotential hydrocarbon table could explain the confinement of the hydrocarbon lakes to high latitudes.

  6. 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.

  7. 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.

  8. Hot-pressed transparent PLZT ceramics from low cost chemical processing

    Directory of Open Access Journals (Sweden)

    I.A. Santos

    2001-10-01

    Full Text Available Lanthanum-modified lead zirconate titanate (PLZT ceramics were obtained with high transmittance in the visible range by a combination of an inexpensive chemical processing and hot pressing. Optical, microstructural, pyroelectric, ferroelectric and dielectric properties characterized in this study attested the applicability of the employed method in the production of PLZT transparent ferroelectric ceramics. In fact, the corresponding analyzed physical parameters are in very good agreement with those obtained in samples traditionally prepared by other methods. Furthermore, due to high sample quality, a phenomenological analysis of the PLZT 10/65/35 relaxor features was performed in these ceramics.

  9. 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.

  10. Influência do sulfato de bário nas características de cerâmica vermelha incorporada com resíduo oleoso inertizado Influence of barium sulfate on the characteristics of red ceramic incorporated with oily waste

    Directory of Open Access Journals (Sweden)

    F. A. N. Silva

    2006-03-01

    Full Text Available A incorporação em cerâmicas de resíduos como borras resultantes da extração, transporte ou refino de petróleo evita seu lançamento no meio ambiente. Por outro lado, é importante avaliar as alterações tecnológicas causadas pela adição do resíduo, sobretudo, no caso de comprometer a qualidade do produto cerâmico. Neste trabalho estudou-se a microestrutura de um material cerâmico contendo 0, 10, 15 e 20% em peso de um resíduo denominado borra de petróleo encapsulada, queimado em temperaturas que variam de 850 a 1100 ºC. A microanálise do material foi realizada através de espectrometria por dispersão de energia (EDS de modo a complementar a análise topográfica feita por microscopia eletrônica de varredura (MEV, para possibilitar a identificação dos elementos químicos presentes, bem como partículas de segunda fase. Os resultados demonstraram que a adição desta borra de petróleo encapsulada provoca alterações tanto na composição química quanto na microestrutura do material cerâmico. Partículas de formato e características distintas das observadas na cerâmica sem adição de resíduo, principalmente partículas de sulfato de bário, foram mapeadas e sua influência discutida.The incorporation into ceramics of residues, such as oily wastes from extraction, transport and refining of petroleum is a way to avoid their disposal to the environment. On the other hand, it is important to evaluate the technological changes caused by the addition of the residue, mainly, in the case that it could compromise the quality of the ceramic product. In this work, the microstructure resulting from the incorporation with 0, 10, 15 and 20 wt.% of a residue, known as encapsulated petroleum waste, into a ceramic material that was fired at temperatures in the range of 850 to 1100 ºC, was investigated. The microanalysis of the material was performed by Energy Dispersed Spectroscopy (EDS to complement the topographic carried out by

  11. Synthesis and characterization of bismuth alkaline titanate powders

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atorresh@ipn.mx [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Dominguez-Crespo, M.A. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Hernandez-Perez, M.A. [ESIQIE, Metalurgia, Instituto Politecnico Nacional, Mexico, D. F (Mexico); Garcia-Zaleta, D.S. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Brachetti-Sibaja, S.B. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo esq. Sor Juana Ines de la Cruz s/n Col. Los Mangos C.P.89440 Cd. Madero Tamaulipas (Mexico)

    2011-06-15

    In this work, samples of bismuth alkaline titanate, (K{sub 0.5}Na{sub 0.5}){sub (2-x/2)}Bi{sub (x/6)}TiO{sub 3}, (x = 0.05-0.75) have been prepared by conventional ceramic technique and molten salts. Metal oxides or carbonates powders were used as starting raw materials. The crystalline phase of the synthesized powders was identified by the X-ray diffraction (XRD) and particle morphology was characterized by scanning electron microscopy (SEM). Solid state reaction method was unsuccessful to obtain pellets. From XRD results, a rhombohedral structure was detected and the parameter lattice were estimated to be a = 5.5478 A and {alpha} = 59.48{sup o}. These parameters were used to refine the structure by Rietveld analysis. SEM results showed several morphologies. Apparently, bismuth is promoting the grain growth whose sizes vary from 30 nm to 180 nm It is expected that these materials can be utilized in practical applications as substitutes for lead zirconatetitanate (PZT)-based ceramics.

  12. 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.

  13. 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.

  14. Influence of lanthanum distribution on dielectric and ferroelectric properties of BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Anita [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Goyal, Parveen K., E-mail: goyalphy@gmail.com [Department of Physics, ARSD College, University of Delhi, Dhaula Kuan, New Delhi 110 021 (India); Thakur, O.P. [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi 110 054 (India); Shukla, A.K. [Department of Physics, Amity Institute of Applied Sciences, Amity University, Noida 201301 (India); Sreenivas, K., E-mail: kondepudysreenivas@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

    2015-02-15

    Structural and electrical properties of Lanthanum substituted barium bismuth titanate BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} (0 ≤ x ≤ 0.50) ceramics prepared by conventional solid-state reaction method have been investigated. Raman spectra reveals the distribution of lanthanum into the perovskite layers and (Bi{sub 2}O{sub 2}){sup 2+} layers of BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics. Room temperature dielectric constant (ε′) increases and considerable reduction in the low frequency (10{sup −2} to 10 Hz) dielectric losses and in dc conductivity (σ{sub dc}) are seen with lanthanum substitution. A critical La content of x ∼0.20 in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} exhibits a well-defined relaxor behavior as seen from the temperature and frequency dependence of the dielectric parameters ε′(T) and ε″(T). The dielectric data fit well to the modified Curie–Weiss law and the Lorentz-type relation and show increasing diffuseness in the phase transition with increasing La content. The temperature dependence of the characteristic relaxation time obtained from the Cole–Cole model shows a good fit to the non-linear Vogel–Fulcher relation. Improvements in the remnant polarization and a stable piezoelectric charge coefficient are seen up to a La content of x ∼0.20. The observed increase in dielectric loss and σ{sub dc} in addition to the diminished ferroelectric/piezoelectric properties for higher La content are explained in terms of changing oxygen vacancy concentration and structural relaxation due to the preferential incorporation of La into the (Bi{sub 2}O{sub 2}){sup 2+} layers as evidenced through the Raman spectroscopy. - Highlights: • La distribution in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics is analyzed through Raman spectroscopy. • Low and a nearly constant loss over wide frequency range (10{sup −2}–10{sup 7} Hz) obtained. • Critical La content x = 0.2 identified for high resistivity and ideal relaxor

  15. 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.

  16. Chemical investigation of Titan and Triton tholins

    Science.gov (United States)

    Mcdonald, Gene D.; Thompson, W. R.; Heinrich, Michael; Khare, Bishun N.; Sagan, Carl

    1994-01-01

    We report chromatographic and spectroscopic analyses of both Titan and Triton tholins, organic solids made from the plasma irradiation of 0.9:0.1 and 0.999:0.001 N2/CH4 gas mixtures, respectively. The lower CH4 mixing ratio leads to a nitrogen-richer tholin (N/C greater than 1), probably including nitrogen heterocyclic compounds. Unlike Titan tholin, bulk Triton tholin is poor in nitriles. From high-pressure liquid chromatography, ultraviolet and infrared spectroscopy, and molecular weight estimation by gel filtration chromatography, we conclude that (1) several H2O-soluble fractions, each with distinct UV and IR spectral signatures, are present, (2) these fractions are not identical in the two tholins, (3) the H2O-soluble fractions of Titan tholins do not contain significant amounts of nitriles, despite the major role of nitriles in bulk Titan tholin, and (4) the H2O-soluble fractions of both tholins are mainly molcules containing about 10 to 50 (C + N) atoms. We report yields of amino acids upon hydrolysis of Titan and Triton tholins. Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

  17. Solid Carbon Produced in an Inductively Coupled Plasma Torch with a Titan Like Atmosphere

    Directory of Open Access Journals (Sweden)

    D. Vacher

    2013-01-01

    Full Text Available Solid carbon is deposited on the surfaces of an inductively coupled plasma torch operating with a Titan like atmosphere plasma gas. The frame of the initial research is the study of the radiative properties of plasma encountered around a spacecraft during its hypersonic entry in upper layers of planetary atmosphere. Deposition of carbon is observed not only on the quartz tube outside the inductor but also on the ceramic protection of the torch injector. Carbon exhibits two types of morphology more or less dense and it is analyzed by various analytic devices as MEB, SEM, TEM, EDS and Raman spectroscopy. The gathered carbon powder shows the presence of nanostructured particles.

  18. Titan as the Abode of Life

    Directory of Open Access Journals (Sweden)

    Christopher P. McKay

    2016-02-01

    Full Text Available Titan is the only world we know, other than Earth, that has a liquid on its surface. It also 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 its 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, azotosomes, 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.

  19. 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.

  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. Synthesis and dielectric properties of MXTi7O16 (M = Ba and Sr;X = Mg and Zn) hollandite ceramics

    Indian Academy of Sciences (India)

    V M Manisha; K P Murali; S N Potty; V Priyadarsini; R Ratheesh

    2004-04-01

    MXTi7O16 (M = Ba and Sr; X = Mg and Zn) ceramics have been synthesized by the conventional solid state ceramic route. The dielectric properties such as dielectric constant (r), loss tangent (tan ) and temperature variation of dielectric constant ($\\tau_{\\varepsilon r}$) of the sintered ceramic compacts are studied using an impedance analyser up to 13 MHz region. The strontium compounds have relatively high dielectric constant and low loss tangent compared to the barium analogue. The phase purity of these materials has been examined using X-ray diffraction studies and microstructure using SEM method.

  5. 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...

  6. 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...

  7. Performance investigation of 1-3 piezoelectric ceramic-cement composite

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Xin, E-mail: chengxin@ujn.edu.cn [University of Jinan, School of Materials Science and Engineering, Jinan 250022 (China); Xu Dongyu, E-mail: xuy_sha@163.com [Shandong University, State Key Lab of Crystal Materials, Jinan 250100 (China); Lu Lingchao; Huang Shifeng [University of Jinan, School of Materials Science and Engineering, Jinan 250022 (China); Jiang Minhua [Shandong University, State Key Lab of Crystal Materials, Jinan 250100 (China)

    2010-05-15

    A 1-3 piezoelectric ceramic-cement composite has been fabricated using sulphoaluminate cement and lead niobium-magnesium zirconate titanate ceramics (P(MN)ZT) as matrix and functional component, respectively. The influences of piezoelectric ceramic volume fraction, aspect ratios of piezoelectric ceramic rods and temperature on the piezoelectric and dielectric properties of the composites were studied. This composite was shown to exhibit an improved electromechanical coupling coefficient with the mechanical quality factor reduced. Furthermore, the acoustic impedance of the composites could also be adjusted to match concrete structures. It has been demonstrated that by adjusting the piezoelectric ceramic volume fraction and shape parameters, the developed composite can be eventually used as sensing element in structural health monitoring.

  8. 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

  9. 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-Hǔckel 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 orecioitator.

  10. Experimental measurement of stress at a four-domain junction in lead zirconate titanate

    Science.gov (United States)

    MacLaren, Ian; Schmitt, Ljubomira A.; Fuess, Hartmut; Kungl, Hans; Hoffmann, Michael J.

    2005-05-01

    A junction between two lamellar bands of ferroelectric domains in a lead zirconate titanate ceramic is analyzed using Kikuchi diffraction patterns in the transmission electron microscope. Indexing of the diffraction patterns allowed the determination of the three-dimensional relative orientation of the four different domains at the junction and thus the characterization of the domain boundaries. The local c /a ratio could also be determined from the misorientations at the domain boundaries. Analysis of the data showed that large stresses were concentrated at the junction, and that this is inevitable at such band junctions. Such stress concentrations could act as nuclei for cracking of the ceramic under additional loading in service, perhaps particularly as a consequence of extended electromechanical cycling. Moreover, the stresses would increase with increasing c /a, making the issues all the more serious for Ti-rich compositions having larger c /a ratios.

  11. Fabrication of Lead Zirconate Titanate Powder Using Ultrasonic Ball Milling Technique

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this research, the ultrasonic ball milling technique has been used to fabricate lead zirconate titanate (PZT) ceramics.PZT with the composition nearly the morphotropic phase boundary (MPB): Pb(Zr0.52 Ti0.48 )O3 was studied. The effect of milling time on phase formation of sample powder was examined by X-ray diffraction technique (XRD). Moreover, the physical, dielectric, piezoelectric properties and microstructure of PZT ceramics were investigated. The present results reveal that the ultrasonic ball milling technique results the homogeneous and small size of PZT powder. Furthermore, there is a significantly change occurs in the size of the particles with the short time of milling process.

  12. Attainment of barium hexa ferrite nanoparticles by a Pechini method;Obtencao de nanoparticulas de hexaferrita de bario pelo metodo Pechini

    Energy Technology Data Exchange (ETDEWEB)

    Galvao, Sheila B.; Timoteo, Flavio Junior J.; Machado, Tercio G.; Souto, Kesia K.O.; Floreoto, Neide T.; Paskocimas, Carlos A., E-mail: sheilabernhard@ufrnet.b [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos Graduacao em Ciencia e Engenharia dos Materiais

    2009-07-01

    The barium hexa ferrites (BaFe{sub 12}O{sub 19}) are used as a compound of materials applied in electronic devices, as medical devices, satellites, dada servers systems, wireless systems and others. The general properties are strongly related to the microstructure and morphology, and the particles size decrease results in advantages to the majority applications, mainly the high-tech thumbnail devices. These magnetic ceramic materials, with perovskite structure, are traditionally prepared my conventional oxide mixture synthesis. In this work was studied the nanoparticle synthesis of BaFe{sub 12}O{sub 19} by the precursors polymeric method (Pechini), using as precursors the barium carbonate and the iron nitrate, under different thermal treatment conditions. The samples were characterized by XRD, Raman spectroscopy, SEM, BET, DTA and TGA. The results presented the attainment of a monophasic powder with particles size around 100 nm. (author)

  13. 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.

  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. 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.

  16. 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.

  17. Energy Deposition Processes in Titan's Upper Atmosphere

    Science.gov (United States)

    Sittler, Edward C., Jr.; Bertucci, Cesar; Coates, Andrew; Cravens, Tom; Dandouras, Iannis; Shemansky, Don

    2008-01-01

    Most of Titan's atmospheric organic and nitrogen chemistry, aerosol formation, and atmospheric loss are driven from external energy sources such as Solar UV, Saturn's magnetosphere, solar wind and galactic cosmic rays. The Solar UV tends to dominate the energy input at lower altitudes of approximately 1100 km but which can extend down to approximately 400 km, while the plasma interaction from Saturn's magnetosphere, Saturn's magnetosheath or solar wind are more important at higher altitudes of approximately 1400 km, but the heavy ion plasma [O(+)] of approximately 2 keV and energetic ions [H(+)] of approximately 30 keV or higher from Saturn's magnetosphere can penetrate below 950km. Cosmic rays with energies of greater than 1 GeV can penetrate much deeper into Titan's atmosphere with most of its energy deposited at approximately 100 km altitude. The haze layer tends to dominate between 100 km and 300 km. The induced magnetic field from Titan's interaction with the external plasma can be very complex and will tend to channel the flow of energy into Titan's upper atmosphere. Cassini observations combined with advanced hybrid simulations of the plasma interaction with Titan's upper atmosphere show significant changes in the character of the interaction with Saturn local time at Titan's orbit where the magnetosphere displays large and systematic changes with local time. The external solar wind can also drive sub-storms within the magnetosphere which can then modify the magnetospheric interaction with Titan. Another important parameter is solar zenith angle (SZA) with respect to the co-rotation direction of the magnetospheric flow. Titan's interaction can contribute to atmospheric loss via pickup ion loss, scavenging of Titan's ionospheric plasma, loss of ionospheric plasma down its induced magnetotail via an ionospheric wind, and non-thermal loss of the atmosphere via heating and sputtering induced by the bombardment of magnetospheric keV ions and electrons. This

  18. Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Xi, Yi [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Peng, Chen [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Wan, Buyong; He, Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)

    2011-06-15

    Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non

  19. 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.

  20. Dielectric behavior of epoxy/BaTiO₃ composites using nanostructured ceramic fibers obtained by electrospinning.

    Science.gov (United States)

    Ávila, H A; Ramajo, L A; Góes, M S; Reboredo, M M; Castro, M S; Parra, R

    2013-02-01

    Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 °C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin.

  1. Atomic hydrogen distribution. [in Titan atmospheric model

    Science.gov (United States)

    Tabarie, N.

    1974-01-01

    Several possible H2 vertical distributions in Titan's atmosphere are considered with the constraint of 5 km-A a total quantity. Approximative calculations show that hydrogen distribution is quite sensitive to two other parameters of Titan's atmosphere: the temperature and the presence of other constituents. The escape fluxes of H and H2 are also estimated as well as the consequent distributions trapped in the Saturnian system.

  2. Near-infrared spectrophotometry of Titan

    Science.gov (United States)

    Trafton, L. M.

    1975-01-01

    Several unusual features in the near-IR spectrum of Titan are examined. Observations during four apparitions establish the reality of the S(1) absorption at 8150.7 A, but the existence of the S(O) absorption at 8272.7 A will require further sightings to become definitively established. These two features are particularly important, as they bear on the abundance of H2 in Titan's atmosphere.

  3. The rotation of Titan and Ganymede

    Science.gov (United States)

    Van Hoolst, Tim; Coyette, Alexis; Baland, Rose-Marie; Trinh, Antony

    2016-10-01

    The rotation rates of Titan and Ganymede, the largest satellites of Saturn and Jupiter, are on average equal to their orbital mean motion. Here we discuss small deviations from the average rotation for both satellites and evaluate the polar motion of Titan induced by its surface fluid layers. We examine different causes at various time scales and assess possible consequences and the potential of using librations and polar motion as probes of the interior structure of the satellites.The rotation rate of Titan and Ganymede cannot be constant on the orbital time scale as a result of the gravitational torque of the central planet acting on the satellites. Titan is moreover expected to show significant polar motion and additional variations in the rotation rate due to angular momentum exchange with the atmosphere, mainly at seasonal periods. Observational evidence for deviations from the synchronous state has been reported several times for Titan but is unfortunately inconclusive. The measurements of the rotation variations are based on determinations of the shift in position of Cassini radar images taken during different flybys. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation variations of Ganymede during its orbital phase around the satellite starting in 2032.We report on different theoretical aspects of the librations and polar motion. We consider the influence of the rheology of the ice shell and take into account Cassini measurements of the external gravitational field and of the topography of Titan and similar Galileo data about Ganymede. We also evaluate the librations and polar motion induced by Titan's hydrocarbon seas and use the most recent results of Titan's atmosphere dynamics. We finally evaluate the potential of rotation variations to constrain the satellite's interior structure, in particular its ice shell and ocean.

  4. Preparation of the Superconductor Substrate: Strontium Titanate

    Science.gov (United States)

    1988-09-01

    single crystals of strontium titanate is derived from the original method developed by Verneuil . 16 The general procedure for the growth of single... crystals growth are reported. The growth direction was determined to be 5 degrees away from the [2111 direction. ICP-emission spectroscopy irdicates... Growth of Strontium Titanate Crystals 5 2.4 Preparation of Substrates 8 3. RESULTS AND CONCLUSIONS 8 REFERENCES 13 Illustrations 1. Schematic Diagram

  5. Solar eclipse sign of intussusception on barium enema.

    Science.gov (United States)

    Raveenthiran, V

    2002-01-01

    The colographic appearance of intussusception is variously described as a claw sign, pincer defect, shouldering effect, and coiled-spring pattern. This report adds a new radiographic sign to the list. An end-on view of an intussusception on barium enema shows a ring of contrast resembling a solar eclipse. Familiarity with this bizarre appearance is desirable, lest it may be mistaken for spillage of barium due to a colonic perforation.

  6. 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.

  7. Infrared spectroscopic, x-ray, and nanoscale characterization of strontium titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J D; Moutinho, H R; Kazmerski, L L [National Renewable Energy Lab., Golden, CO (United States); Mueller, C H; Rivkin, T V; Treece, R E [Superconducting Core Technologies, Inc., Golden, CO (United States); Dalberth, M; Rogers, C T [Colorado Univ., Boulder, CO (United States). Dept. of Physics

    1996-06-01

    Attenuated total reflectance (ATR) measurements were performed using Fourier transform infrared (FTIR) spectroscopy in the ATR mode with a thallium iodobromide (KRS-5) crystal to measure the frequencies of the v{sub 3} and v{sub 4} phonon absorption bands in thin Sr titanate films deposited on single-crystal Y-Ba Cu oxide (YBCO), La aluminate, Mg oxide, and Sr titanate substrates. The KRS-5 crystal enabled FTIR-ATR measurements at frequencies above 400 cm{sup -1}. Atomic force microscopy (AFM) and x-ray diffraction (XRD) measurements were also made to further characterize the films. The measurements were repeated on single-crystal specimens of Sr titanate and the substrates for comparison. Softening in the frequency of the v{sub 4} transverse optical phonon in the lattice-mismatched films below the established value of 544 cm{sup -1} is indicative of the highly textured, polycrystalline ceramic nature of the films and is consistent with the XRD and AFM results.

  8. Synthesis and characterization of zinc titanate nano-crystal powders obtained by mechanical activation

    Directory of Open Access Journals (Sweden)

    Obradović Nina

    2005-01-01

    Full Text Available Development of dielectric materials for microwave frequencies is increasing with rapid progress in mobile and satellite communications systems, where zinc titanates have found application due to their semi-conducting and dielectric properties. Mechanical activation by grinding is a well-known method and common part of the powder preparation route in the field of ceramics. The aim of this work is investigation of the influence of experimental conditions for mechanochemical synthesis of zinc orthotitanate. Starting powder mixtures of ZnO and TiO2, in the molar ratio that is in accordance with the stoichiometry of zinc titanate spinel type Zn2TiO4, were mechanically activated using a high-energy planetary ball mill. The process of mechanical activation was performed during different time intervals from 0 to 300 minutes. Microstructure characterization was determined by X-ray diffraction analysis and scanning electron microscopy. Also, the specific surface area (SSA of powders samples was measured by a nitrogen gas sorption analyzer using the BET method. The very first traces of zinc titanate are detectable after only 5 minutes of activation. The most interesting occurrence during the mechanical method of activation is that we have an almost pure phase after 90 minutes.

  9. Development and application of ferrite materials for low temperature co-fired ceramic technology

    Science.gov (United States)

    Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

    2013-11-01

    Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 °C. These ferrite materials are research focuses and are applied in many ways in electronics.

  10. Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materials

    Science.gov (United States)

    1988-09-15

    the strength and fatigue characteristics of ZBLAN (zirconium barium-lanthanum-aluminum-sodium fluoride) optical glass fiber obtained from British...Surface Chemistry and Structural Effects in the Stress Corrosion of Glass and Ceramic Materlals 12. PERSONAL AUTHOR(S) Carlo G. Pantano 13a. TYPE OF...fluorozirconate glasses . °. DTICS ELEC T E DEC 09 I 20. DISTRIBUTION/ AVAILABILITY OF ABSTRACT 21.-A% RACT SECURITY CLASSIFICATION [BUNCLASSIFIED/UNLIMITED

  11. 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...

  12. Studies on the Structure and Properties of Multiphase Al2O3 Abrasion-resistant Ceramics

    Institute of Scientific and Technical Information of China (English)

    WU Ren-Ping; YU Yan; RUAN Yu-Zhong

    2006-01-01

    The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstructure of ceramic are characterized by means of XRD,SEM, etc., and the physical and mechanical properties are also tested. The results show that besides the phase of corundum, a little mullite, Mg-Al spinel and hyalophane phases also exist in the product. These phases are produced via reaction in-situ, which can inhibit the overgrowth of Al2O3grain in grain boundary, and improve the integral property of the material.

  13. Fabrication and Characterization of a Lead Zirconate Titanate Micro Energy Harvester Based on Eutectic Bonding

    Institute of Scientific and Technical Information of China (English)

    LI Yi-Gui; SUN Jian; YANG Chun-Sheng; LIU Jing-Quan; SUGIYAMA Susumu; TANAKA Katsuhiko

    2011-01-01

    A lead zirconate titanate(PZT)-Si energy harvester cantilever with PZT bulk ceramics is fabricated by eutectic bonding, polishing and dicing processes. The feasibility of this process is studied using a successful operation of the cantilever in both actuation and harvesting modes. The first prototype made from a PZT-Au-Si cantiliever is tested. The testing results show the voltage output of 632mV at the frequency of 815Hz when the excitation acceleration is 0.5 g. The PZT and silicon layers are bonded together to form a sandwiched structure using a gold layer as an intermediate layer.%@@ A lead zirconate titanate(PZT)-Si energy harvester cantilever with PZT bulk ceramics is fabricated by eutectic bonding, polishing and dicing processes.The feasibility of this process is studied using a successful operation of the cantilever in both actuation and harvesting modes.The first prototype made from a PZT-Au-Si cantiliever is tested.The testing results show the voltage output of 632mV at the frequency of 815 Hz when the excitation acceleration is 0.5 g.The PZT and silicon layers are bonded together to form a sandwiched structure using a gold layer as an intermediate layer.

  14. High H- ionic conductivity in barium hydride

    Science.gov (United States)

    Verbraeken, Maarten C.; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T. S.

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H-) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm-1 at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  15. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

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

    2015-01-01

    degrees C and evidence was found for the solidification of the melt at 380-440 degrees C, i.e. simultaneously with the onset of decomposition. Between 400 degrees C and 520 degrees C (Ba(C4H9CO2)(2) decomposes in two main steps, first into BaCO3 with release of C4H9COC4H9 (5-nonanone), whereas final......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...... conversion to BaO takes place with release of CO2. Elemental carbon that is left as a by-product is finally slowly burned by the residual oxygen present in the Ar atmosphere. (C) 2015 Elsevier B.V. All rights reserved....

  16. Chemical compositions of four barium stars

    CERN Document Server

    Liang, Y C; Chen, Y Q; Qiu, H M; Zhang, B

    2003-01-01

    Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and HD 98839 are studied based on high resolution, high signal-to-noise Echelle spectra. Results show that all of them are disk stars. Their \\alpha and iron peak elements are similar to the solar abundances. The neutron-capture process elements are overabundant relative to the Solar. The heavy-element abundances of the strong Ba star HD 50082 are higher than those of other three mild Ba stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD 26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun (+0.75,-0.78M_sun), respectively, which are consistent with the average mass of mild Ba stars. We also calculate the theoretical abundances of Ba stars by combining the AGB stars nucleosynthesis and wind accretion formation scenario of Ba binary systems. The comparisons between the observed abundance patterns of the sample stars with the th...

  17. Structural and tidal models of Titan and inferences on cryovolcanism

    OpenAIRE

    Sohl, F.; Solomonidou, A.; Wagner, F.W.; Coustenis, A.; Hussmann, H.; Schulze-Makuch, D.

    2014-01-01

    Titan, Saturn's largest satellite, is subject to solid body tides exerted by Saturn on the timescale of its orbital period. The tide-induced internal redistribution of mass results in tidal stress variations, which could play a major role for Titan's geologic surface record. We construct models of Titan's interior that are consistent with the satellite's mean density, polar moment-of-inertia factor, obliquity, and tidal potential Love number k2 as derived from Cassini observations of Titan's ...

  18. Seasonal Evolution of Titan's Atmospheric Polar Vortices

    Science.gov (United States)

    Teanby, Nicholas A.; Irwin, P. G.; Nixon, C. A.; de Kok, R.; Vinatier, S.; Coustenis, A.; Sefton-Nash, E.; Calcutt, S. B.; Flasar, F. M.

    2013-10-01

    Titan is the largest satellite of Saturn and is the only moon in our solar system to have a significant atmosphere. Titan's middle-atmosphere circulation usually comprises a single hemisphere-to-hemisphere meridional circulation cell, with upwelling air in the summer hemisphere and subsiding air at the winter pole with an associated winter polar vortex. Titan has an axial tilt (obliquity) of 26.7degrees, so during its 29.5 Earth year annual cycle pronounced seasonal effects are expected as the relative solar insolation in each hemisphere changes. The most dramatic of these changes is predicted to be the reversal in global meridional circulation as the peak solar heating switches hemispheres after an equinox. Since northern spring equinox in mid-2009, Titan's atmosphere has demonstrated dramatic changes in temperature, composition, and aerosol distribution. These changes indicate major changes to the atmospheric circulation pattern have indeed occurred. Here we use nine years of Cassini/CIRS infrared spectra to determine the temperature and composition evolution of the atmosphere through northern-fall to northern-spring. Particularly dramatic changes are observed at the poles, where a new south polar hot-spot/vortex has been forming. The north polar vortex also appears to be weakening throughout this period. Furthermore, the meridional circulation reversal, predicted by numerical models, occurred a mere six months after equinox, showing that despite Titan's long annual cycle, rapid changes are possible. This gives us new insight into vortex formation processes and atmospheric dynamics.

  19. 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.

  20. Synthesis, microstructural and electrical characterization of ceramic compounds based on strontium and calcium titanates and iron-oxide; Sintese, caracterizacao microestrutural e eletrica de compostos ceramicos a base de solucoes solidas de titanato de estroncio, titanato de calcio e oxido de ferro

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Joao Roberto do

    2011-07-01

    Ca{sub x}Sr{sub 1-x}Ti{sub 1-y}Fe{sub y}O{sub 3-}{delta}, X = 0, 0.5 and 1.0, y = 0 and 0.35, ceramic compounds were synthesized by reactive solid state synthesis of CaCO{sub 3}, SrCO{sub 3}, TiO{sub 2} and Fe{sub 2}O{sub 3}, and by the polymeric precursor technique. The ceramic powders were evaluated by thermogravimetry and differential thermal analysis, X-ray diffraction and scanning electron microscopy. Sintered ceramic pellets were analyzed by X-ray diffraction, scanning electron microscopy, scanning probe microscopy and impedance spectroscopy. The electromotive force resulting from the exposing the pellets to partial pressure de oxygen in the {approx}50 ppm in the 600-1100 Degree-Celsius range was monitored using an experimental setup consisting of an oxygen electrochemical pump with yttria-stabilized zirconia transducer and sensor. Rietveld analysis of the X-ray data allowed for determining the crystalline structures: cubic perovskite (y = 0) and orthorhombic perovskite (y {ne} 0). The electrical conductivity was determined by the two probe impedance spectroscopy measurements in the 5 Hz-13 MHz frequency range from room temperature to approximately 200 Degree-Celsius . The deconvolution of the [-Z{sup (}{omega}) x Z'({omega})] impedance diagrams in the 300 < T(K) < 500 range shows two semicircles due to intragranular (bulk) and intergranular (grain boundary) contributions to the electrical resistivity. Sintered pellets using powders prepared by the ceramic route present higher inter- and intragranular resistivity values than pellets prepared with chemically synthesized powders. The emf signal under exposure oxygen shows that these compounds may be used in oxygen sensing devices in the 600 - 1100 Degree-Celsius range. Scanning probe microscopy topographic analysis of the polished and thermally etched surfaces of the pellets gave details of grain morphology, showing that pellets prepared with powders synthesized by the chemical route are less porous than

  1. Détermination de l'énergie de surface d'alumines et de titanates de baryum utilisés pour la préparation de céramiques : influence d'un traitement thermique

    Science.gov (United States)

    Papirer, E.; Perrin, J. M.; Siffert, B.; Philipponneau, G.

    1991-05-01

    Surface characteristics of powders used for the preparation of ceramics determine the physical interactions potential between constituents and condition, in particular, the stability of slurries. Inverse Gas Chromatography (I.G.C.) applied to aluminas and barium titanates, appears to be a well suited method for the measurement, on the one hand, of the dispersive component (γ^D_S) of the surface energy and, on the other hand, of a specific interaction parameter (I_{sp}) which accounts for all possible interactions, except London interactions. It is shown that, firstly, the chemical surface composition (presence of impurities or Ba/Ti ratios) influences strongly the values of γ^D_S and I_{sp} and, secondly, the heat treatment of certain aluminas (below 500 °C) modifies in an unexpected way the same values. In that case, the results may be explained supposing the existence, on the alumina surfaces, of a thin hydrated oxide layer which is formed during ageing in humid atmosphere. This layer, of the boehmite type, transforms into γ alumina around 350-400 °C, a transformation accompanied by important variations of γ^D_S This study underlines the importance of a thorough physico-chemical control of the ceramic powders and of their conditioning. Les caractéristiques de surface des poudres entrant dans la préparation des céramiques déterminent les capacités d'interactions physiques entre constituants et conditionnent, en particulier, la stabilité des barbotines. La chromatographie gazeuse inverse (C.G.I.), appliquée aux alumines et aux titanates de baryum, s'avère comme une méthode de choix pour la mesure d'une part, de la composante dispersive (γ^D_S) de l'énergie de surface et d'autre part, d'un paramètre d'interaction spécifique (I_{sp}) qui rend compte de toutes les possibilités d'interactions à l'exception de celles de London. On montre, premièrement, que la composition chimique de surface (présence d'impuretés, ou rapport Ba/Ti) influe

  2. 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.

  3. Optical properties of Er{sup 3+}-doped strontium barium niobate nanocrystals obtained by thermal treatment in glass

    Energy Technology Data Exchange (ETDEWEB)

    Haro-Gonzalez, P. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain)], E-mail: patharo@ull.es; Lahoz, F. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Platas, J. [Dep. of Fisica Fundamental II, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Caceres, J.M. [Dep. of Edafologia y Geologia, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Perez, S. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain); Marrero-Lopez, D. [Dep. of Quimica Inorganica, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Capuj, N. [Dep. of Fisica Basica, Universidad de La Laguna, 38206 La Laguna, S/C de Tenerife (Spain); Martin, I.R. [Dep. of Fisica Fundamental Experimental, Electronica y Sistemas, Universidad de La Laguna Avda Astrofisico Franscisco Sanchez, 38206 La Laguna, S/C de Tenerife (Spain)

    2008-05-15

    Measurements of the optical properties of Er{sup 3+} ions in strontium barium niobate glass and glass ceramics have been carried out. The glasses have been fabricated using a melt-quenching method, and the glass ceramic samples have been obtained from the glass precursor by a thermal treatment. The ceramic samples formed by a glassy phase, and a crystalline phase contains nanocrystals of Sr{sub 1-x}Ba{sub x}Nb{sub 2}O{sub 6} (SBN) doped with Er{sup 3+} ions with a mean size of {approx}50 nm, as confirmed with XRD. Green up-conversion emission has been obtained under excitation at 800 nm, and the temporal evolution of this emission has been reported with the purpose of determining the involved up-conversion mechanism. These optical measures have confirmed that the Er{sup 3+} ions have been incorporated into the SBN matrix, after a thermal treatment, which produced an increment of the up-conversion efficiency.

  4. Both barium and calcium activate neuronal potassium currents

    Energy Technology Data Exchange (ETDEWEB)

    Ribera, A.B.; Spitzer, N.C.

    1987-09-01

    Amphibian spinal neurons in culture possess both rapidly inactivating and sustained calcium-dependent potassium current components, similar to those described for other cells. Divalent cation-dependent whole-cell outward currents were isolated by subtracting the voltage-dependent potassium currents recorded from Xenopus laevis neurons in the presence of impermeant cadmium from the currents produced without cadmium but in the presence of permeant divalent cations. These concentrations of permeant ions were low enough to avoid contamination by macroscopic inward currents through calcium channels. Calcium-dependent potassium currents were reduced by 1 ..mu..M tetraethylammonium. These currents can also be activated by barium or strontium. Barium as well as calcium activated outward currents in young neurons (6-8 hr) and in relatively mature neurons (19-26 hr in vitro). However, barium influx appeared to suppress the sustained voltage-dependent potassium current in most cells. Barium also activated at least one class of potassium channels observed in excised membrane patches, whole blocking others. The blocking action may have masked and hindered detection of the stimulatory action of barium in other systems.

  5. Ag+掺杂钛酸锶钡基玻璃陶瓷的显微结构和介电性能%Microstructure and Dielectric Properties of Silver Ions Doped BST Glass Ceramic

    Institute of Scientific and Technical Information of China (English)

    徐超; 沈波; 翟继卫

    2012-01-01

    Barium strontium titanate(BST) based glass was prepared by a melting method,and then the glass samples were heat treated under different process conditions to obtain the BST based glass ceramics.The thermodynamic characteristics during the process of crystallization were investigated by differential scanning calorimeter.The microstructure and phase structure of glass ce-ramics were analyzed by scanning electron microscopy and X-ray diffraction,respectively.Moreover,the dielectric properties of glass ceramics and the breakdown strength were determined.The results show that the doping of a certain amount(i.e.,0.3% in mass) of Ag+ ion can reduce the crystallization temperature from 885 to 840 ℃,which is conducive to the precipitation of the BST.Also,the doping of Ag+ ion enhanced the dielectric constant of the BST based glass ceramics and maintained a low level of dielectric loss.In addition,the doping of Ag+ ion improved the breakdown strength,i.e.,the samples heated at 800 ℃ had the breakdown strength of 96.3 kV/mm,which was higher than that of the undoped BST based glass(52.5 kV/mm).%采用熔融法制备了钛酸锶钡(barium strontium titanate,BST)基玻璃,然后将此玻璃样品在不同的温度下进行热处理得到BST基玻璃陶瓷,采用差热分析研究了BST基玻璃陶瓷析晶过程中的热力学特征,用扫描电子显微镜和X射线衍射分别分析了玻璃陶瓷的显微结构和相结构,并且系统研究了该玻璃陶瓷的介电特性以及耐击穿电场强度。结果表明:0.3%(质量分数)Ag+掺杂时,BST基玻璃中BST相的析晶温度从885℃下降到840℃,有利于玻璃体中BST晶体的析出。另外,Ag+的掺杂有利于提高BST基玻璃陶瓷的介电常数,同时能维持较低的介电损耗。此外,Ag+掺杂能够提高BST基玻璃的耐击穿电场强度,其在800℃热处理后,可达96.3 kV/mm,高于未掺杂Ag+的BST基玻璃的52.5kV/mm。

  6. Fabrication of zinc titanate nanofibers by electrospinning technique

    Energy Technology Data Exchange (ETDEWEB)

    Cai Zongying, E-mail: czy1106@sina.co [Institute of Advanced Materials, Mechanical Engineering College, Shijiazhuang, Hebei 050003 (China); Li Junshou; Wang Yigang [Institute of Advanced Materials, Mechanical Engineering College, Shijiazhuang, Hebei 050003 (China)

    2010-01-07

    The zinc titanate composite nanofibers were prepared using electrospinning method combining sol-gel process followed by calcining the precursor PVP/Zn(CH{sub 3}COO){sub 2}-Ti(OC{sub 4}H{sub 9}){sub 4} fibers under air in the temperature range of 400-700 {sup o}C. The nanofibers were characterized by thermal field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), thermal gravimetric and differential thermal analysis (TG-DTA). FE-SEM micrographs indicated that the surfaces of the nanofibers are uniform and smooth and the diameter of the fiber decreasing as the calcination temperature increasing. It is also found that ZnO-TiO{sub 2} ceramic fibers including ZnTiO{sub 3}, Zn{sub 2}TiO{sub 4} and rutile phase were synthesized by calcining the precursor PVP/Zn(CH{sub 3}COO){sub 2}-Ti(OC{sub 4}H{sub 9}){sub 4} composite fibers at 700 {sup o}C.

  7. 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...

  8. Melt processed multiphase ceramic waste forms for nuclear waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, Jake, E-mail: jake.amoroso@srs.gov [Savannah River National Laboratory, Aiken, SC 29808 (United States); Marra, James C. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Tang, Ming [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lin, Ye; Chen, Fanglin [University of South Carolina, Columbia, SC 29208 (United States); Su, Dong [Brookhaven National Laboratory, Upton, NY 11973 (United States); Brinkman, Kyle S. [Clemson University, Clemson, SC 29634 (United States)

    2014-11-15

    Highlights: • We explored the feasibility of melt processing multiphase titanate-based ceramics. • Melt processing produced phases obtained by alternative processing methods. • Phases incorporated multiple lanthanides and transition metals. • Processing in reducing atmosphere suppressed un-desirable Cs–Mo coupling. • Cr partitions to and stabilizes the hollandite phase, which promotes Cs retention. - Abstract: Ceramic waste forms are promising hosts for nuclear waste immobilization as they have the potential for increased durability and waste loading compared with conventional borosilicate glass waste forms. Ceramics are generally processed using hot pressing, spark plasma sintering, and conventional solid-state reaction, however such methods can be prohibitively expensive or impractical at production scales. Recently, melt processing has been investigated as an alternative to solid-state sintering methods. Given that melter technology is currently in use for High Level Waste (HLW) vitrification in several countries, the technology readiness of melt processing appears to be advantageous over sintering methods. This work reports the development of candidate multi-phase ceramic compositions processed from a melt. Cr additions, developed to promote the formation and stability of a Cs containing hollandite phase were successfully incorporated into melt processed multi-phase ceramics. Control of the reduction–oxidation (Redox) conditions suppressed undesirable Cs–Mo containing phases, and additions of Al and Fe reduced the melting temperature.

  9. Dielectric properties of neodymium-modified PLZT ceramics

    Science.gov (United States)

    Płońska, M.; Adamczyk, M.

    2015-08-01

    Relaxor ferroelectrics or relaxors are a class of disordered single crystals and ceramic materials, of peculiar structure as well as properties. The commonly known examples of such materials are Pb(Mg,Nb)O3 (PMN) ceramics as well as single crystals. The second most extensively studied relaxor ceramics is lanthanum-doped lead zirconate-titanate, described as x/65/35 PLZT when lanthanum content is x = 6-10 at%. Throughout the last few decades, there has been an increasing interest in rare-earth-doped PLZT ceramics, because PLZT can be easily substituted with lanthanide elements for La3+ ions. For this reason, the present studies concern the changes in microstructure and crystal structure as well as in dielectric properties, caused by modification of 8/65/35 PLZT with neodymium dopant. Modification of this material with Nd3+ influences the microstructure, electrooptical and dielectric properties, whereas the changes in crystal structure are slight. It was also observed that the maximum value of dielectric properties decreases and moves to a low temperature. Described changes in physical properties are associated with the significant improvement of relaxor properties, characteristic for pure 8/65/35 PLZT ceramics.

  10. 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.

  11. 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.

  12. Durability of Alite-calcium Barium Sulphoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    LU Lingchao; LU Zeye; LIU Shiquan; WANG Shoude; CHENG Xin

    2009-01-01

    The durability of the cement was mainly studied.Under 1.0 MPa of hydraulic pressure for 8 hours,water could penetrate completely through the sample made by portland cement,but could not penetrate through that by alite-barium sulphoaluminate cement.Under the condition of freezing and thawing cycle,the loss ratio of compressive strength of the cement was only about 17.3%at curing 28 d ages,but the loss of portland cement was as high as 29.5%.Alite-calcium bar-ium sulphoaluminate cement also has an excellent resistance to sulfate attack.The coefficients of resistance to sulfate attack of the cement exceeded 1.0.Meanwhile,the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.

  13. 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.

  14. Barium-borate-flyash glasses: As radiation shielding materials

    Science.gov (United States)

    Singh, Sukhpal; Kumar, Ashok; Singh, Devinder; Thind, Kulwant Singh; Mudahar, Gurmel S.

    2008-01-01

    The attenuation coefficients of barium-borate-flyash glasses have been measured for γ-ray photon energies of 356, 662, 1173 and 1332 keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free path (mfp), effective atomic number and electron density. Good agreements have been observed between experimental and theoretical values of these parameters. From the studies of the obtained results it is reported here that from the shielding point of view the barium-borate-flyash glasses are better shields to γ-radiations in comparison to the standard radiation shielding concretes and also to the ordinary barium-borate glasses.

  15. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  16. Ceramic Matrix Composites .

    Directory of Open Access Journals (Sweden)

    J. Mukerji

    1993-10-01

    Full Text Available The present state of the knowledge of ceramic-matrix composites have been reviewed. The fracture toughness of present structural ceramics are not enough to permit design of high performance machines with ceramic parts. They also fail by catastrophic brittle fracture. It is generally believed that further improvement of fracture toughness is only possible by making composites of ceramics with ceramic fibre, particulate or platelets. Only ceramic-matrix composites capable of working above 1000 degree centigrade has been dealt with keeping reinforced plastics and metal-reinforced ceramics outside the purview. The author has discussed the basic mechanisms of toughening and fabrication of composites and the difficulties involved. Properties of available fibres and whiskers have been given. The best results obtained so far have been indicated. The limitations of improvement in properties of ceramic-matrix composites have been discussed.

  17. 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....

  18. Ceramic art in sculpture

    OpenAIRE

    Rokavec, Eva

    2014-01-01

    Diploma seminar speaks of ceramics as a field of artistic expression and not just as pottery craft. I presented short overview of developing ceramic sculpture and its changing role. Clay inspires design and touch more than other sculpture media. It starts as early as in prehistory. Although it sometimes seems that was sculptural ceramics neglected in art history overview, it was not so in actual praxis. There is a rich tradition of ceramics in the East and also in Europe during the renaissanc...

  19. XPS Study on Barium Lanthanum Magnesium Niobate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Relaxor-type ferroelectric perovskites attract a lot of attentions due to their excellent dielectric and electrostrictive properties. (Ba,La)(Mg,Nb)O3(BLMN) ceramics were synthesized from oxides by sintering in airs using a conventional mixed oxide process. Thermogravimetry-differential analyzer (TG-DTA) analysis shows that the fired temperature of the Ba(Mg1/3, Nb2/3)O3 is above 1627.2 K. From the study of X-ray diffraction (XRD) patterns, it is founded that the amount of the perovskite phase increases with the increasing amount of La2O3. Furthermore, by the X-ray photoelectron spectroscopy (XPS) analysis, it is discovered that the amount of Nb4+ is increased as La2O3 dopant increases from 0 to 0.04.

  20. 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.

  1. 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.

  2. 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.

  3. Light element ceramics

    OpenAIRE

    Rao, KJ; Varma, KBR; Raju, AR

    1988-01-01

    An overview of a few structually important light element ceramics is presented. Included in the overview are silicon nitide, sialon, aluminium nitride, boron carbide and silicon carbide. Methods of preparation, characterization and industrial applications of these ceramics are summarized. Mechanical properties, industrial production techniques and principal uses of these ceramics are emphasized.

  4. Ceramic to metal seal

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Gary S. (Albuquerque, NM); Wilcox, Paul D. (Albuquerque, NM)

    1976-01-01

    Providing a high strength, hermetic ceramic to metal seal by essentially heating a wire-like metal gasket and a ceramic member, which have been chemically cleaned, while simultaneously deforming from about 50 to 95 percent the metal gasket against the ceramic member at a temperature of about 30 to 75 percent of the melting temperature of the metal gasket.

  5. Novel Synthesis of Thallium-Barium - Superconductors

    Science.gov (United States)

    Bayya, Shyam Sundar

    This thesis addresses the processing difficulties associated with the synthesis of double layer superconductors in the Tl-Ba-Ca-Cu-O system and presents some novel processing techniques for their synthesis. Tl-2212 and Tl-2223 superconducting powders were made by a self-propagating high-temperature synthesis (SHS). Preheating of the reactants was necessary to self sustain the reactions. This method produced a higher amount of the Tl-2223 phase as compared to the powders produced from furnace synthesis. A microwave assisted combustion synthesis (MACS) was developed to synthesize Tl-2212 and Tl-2223 powders. A short reaction time in the microwave oven resulted in a high fraction of the Tl-2212 phase. A post-heat treatment was required to synthesize Tl-2212 and Tl-2223 phases of high purity. Synthesis of Tl-2201, Tl-2212 and Tl-2223 by melt quench and glass ceramic processes was attempted. These compositions didn't form glasses on melt quenching, however, a heat treatment resulted in Tl-2201 and Tl-2212 phases from their stoichiometric compositions. A low purity Tl -2223 sample was obtained by this process from its stoichiometric composition. Smaller additions of boric acid or gallia to the batches did not improve the glass formability of the systems. Higher additions of boric acid improved the glass formability but they crystallized binary and complex borates on devitrification. Smaller additions of gallia crystallized the superconducting phases. A molten salt synthesis was developed to prepare Tl-2201 and Tl-2212 superconducting powders. Tl-2212 was found to be stable over a wide composition range. Sodium containing salts were found to deteriorate the superconducting properties. Optimum growth and good electrical properties of Tl-2212 were obtained from the KCl salt. A doctor blade process was used to fabricate grain-oriented ceramic using these powders.

  6. NMR identification of hexamethylenetetramine and its precursor in Titan tholins: Implications for Titan prebiotic chemistry

    Science.gov (United States)

    He, Chao; Lin, Guangxin; Smith, Mark A.

    2012-08-01

    The reddish brown organic haze surrounding Titan has been investigated using methods including remote observation, direct exploration (the Cassini mission) and laboratory simulations, but its formation mechanism and the contributing chemical structures and prebiotic potential are still not well understood. We report here the structural investigation of the 13C and 15N labeled, simulated Titan haze aerosol (tholin) using solution-state NMR. These spectra demonstrate a material composed of a mixture of moderate polymer and small molecules. Hexamethylenetetramine (HMT) is identified as the major small molecule component in the Titan tholin and its precursor (1,3,5-hexahydrotriazine) is also detected. We discuss the formation mechanism of HMT and its implications for Titan and early Earth prebiotic chemistry.

  7. The Titan Haze Simulation experiment on COSmIC: Probing Titan's atmospheric chemistry at low temperature

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Ricketts, Claire L.; Salama, Farid

    2014-11-01

    The aim of the Titan Haze Simulation (THS) experiment is to contribute to a better understanding of aerosol formation in Titan's atmosphere through the study of the chemical formation pathways that link the simpler gas phase molecules resulting from the first steps of the N2-CH4 chemistry, to the more complex gas phase precursors of aerosols; and more specifically, to investigate the role of polycyclic aromatic hydrocarbons (PAHs) and nitrogenated polycyclic aromatic hydrocarbons (PANHs), among other hydrocarbons, in this process. In the THS experiment developed at the NASA Ames Cosmic simulation facility (COSmIC), Titan's atmospheric chemistry is simulated by a pulsed plasma jet expansion at temperature conditions (∼150 K) close to those found in Titan's atmosphere in regions where aerosols are formed. In addition, because of the very short residence time of the gas in the plasma discharge, only the initial steps of the chemistry occur, making the COSmIC/THS a unique tool to study the first and intermediate (when adding heavier precursors to the initial N2-CH4 mixture) steps of Titan's atmospheric chemistry at low temperature as shown in the study presented here. We further illustrate the potential of COSmIC/THS for the simulation of Titan's atmospheric chemistry by presenting very promising results from a preliminary comparison of the laboratory data to data from the Cassini Plasma Spectrometer-Ion Beam Spectrometer (CAPS-IBS) instrument.

  8. Creep in ceramics

    CERN Document Server

    Pelleg, Joshua

    2017-01-01

    This textbook is one of its kind, since there are no other books on Creep in Ceramics. The book consist of two parts: A and B. In part A general knowledge of creep in ceramics is considered, while part B specifies creep in technologically important ceramics. Part B covers creep in oxide ceramics, carnides and nitrides. While covering all relevant information regarding raw materials and characterization of creep in ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  9. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  10. 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.

  11. Evolution of an Early Titan Atmosphere: Comment

    CERN Document Server

    Johnson, Robert E; Volkov, Alexey N

    2015-01-01

    Escape of an early atmosphere from Titan, during which time NH3 could be converted by photolysis into the present N2 dominated atmosphere, is an important problem in planetary science. Recently Gilliam and Lerman (2014) estimated escape driven by the surface temperature and pressure, which we show gave loss rates that are orders of magnitude too large. Their model, related to Jeans escape from an isothermal atmosphere, was used to show that escape driven only by surface heating would deplete the atmospheric inventory of N for a suggested Titan accretion temperature of ~355 K. Therefore, they concluded that the accretion temperature must be lower in order to retain the present Titan atmosphere. Here we show that the near surface atmospheric temperature is essentially irrelevant for determining the atmospheric loss rate from Titan and that escape is predominantly driven by solar heating of the upper atmosphere. We also give a rough estimate of the escape rate in the early solar system (~10^4 kg/s) consistent wi...

  12. Modeling survey of ices in Titan's stratosphere

    Science.gov (United States)

    Barth, Erika L.

    2017-03-01

    Processes in Titan's upper atmosphere, such as photochemical destruction of methane along with the destruction of nitrogen molecules from energetic electrons, result in the production of a number of hydrocarbon and nitrile compounds which are capable of condensing in the colder temperatures of Titan's mid to lower stratosphere. Stratospheric ices can contribute to the opacity of Titan's atmosphere as well as affect the chemistry of the more optically thick clouds seen in the troposphere, should they serve as condensation nuclei. We model the microphysics of a dozen trace species in Titan's atmosphere and show the resulting cloud properties. Clouds form and settle into layers between 50 and 80 km. Condensation timescales can be slow, with half the species only growing to a radius ≲ 1 μ m . Ethane cloud particles grow the largest with radii up to 20 μm. Factors such as the vapor pressure equation, nucleation rate, gas abundance, and temperature profile can have a significant effect on the appearance of the cloud particles. Though the data on optical constants is sparse for many of these ices, estimates show opacities of 10-5 -10-3 for visible wavelengths.

  13. 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...

  14. TandEM: Titan and Enceladus mission

    Science.gov (United States)

    Coustenis, A.; Atreya, S.K.; Balint, T.; Brown, R.H.; Dougherty, M.K.; Ferri, F.; Fulchignoni, M.; Gautier, D.; Gowen, R.A.; Griffith, C.A.; Gurvits, L.I.; Jaumann, R.; Langevin, Y.; Leese, M.R.; Lunine, J.I.; McKay, C.P.; Moussas, X.; Muller-Wodarg, I.; Neubauer, F.; Owen, T.C.; Raulin, F.; Sittler, E.C.; Sohl, F.; Sotin, C.; Tobie, G.; Tokano, T.; Turtle, E.P.; Wahlund, J.-E.; Waite, J.H.; Baines, K.H.; Blamont, J.; Coates, A.J.; Dandouras, I.; Krimigis, T.; Lellouch, E.; Lorenz, R.D.; Morse, A.; Porco, C.C.; Hirtzig, M.; Saur, J.; Spilker, T.; Zarnecki, J.C.; Choi, E.; Achilleos, N.; Amils, R.; Annan, P.; Atkinson, D.H.; Benilan, Y.; Bertucci, C.; Bezard, B.; Bjoraker, G.L.; Blanc, M.; Boireau, L.; Bouman, J.; Cabane, M.; Capria, M.T.; Chassefiere, E.; Coll, P.; Combes, M.; Cooper, J.F.; Coradini, A.; Crary, F.; Cravens, T.; Daglis, I.A.; de Angelis, E.; De Bergh, C.; de Pater, I.; Dunford, C.; Durry, G.; Dutuit, O.; Fairbrother, D.; Flasar, F.M.; Fortes, A.D.; Frampton, R.; Fujimoto, M.; Galand, M.; Grasset, O.; Grott, M.; Haltigin, T.; Herique, A.; Hersant, F.; Hussmann, H.; Ip, W.; Johnson, R.; Kallio, E.; Kempf, S.; Knapmeyer, M.; Kofman, W.; Koop, R.; Kostiuk, T.; Krupp, N.; Kuppers, M.; Lammer, H.; Lara, L.-M.; Lavvas, P.; Le, Mouelic S.; Lebonnois, S.; Ledvina, S.; Li, J.; Livengood, T.A.; Lopes, R.M.; Lopez-Moreno, J. -J.; Luz, D.; Mahaffy, P.R.; Mall, U.; Martinez-Frias, J.; Marty, B.; McCord, T.; Salvan, C.M.; Milillo, A.; Mitchell, D.G.; Modolo, R.; Mousis, O.; Nakamura, M.; Neish, C.D.; Nixon, C.A.; Mvondo, D.N.; Orton, G.; Paetzold, M.; Pitman, J.; Pogrebenko, S.; Pollard, W.; Prieto-Ballesteros, O.; Rannou, P.; Reh, K.; Richter, L.; Robb, F.T.; Rodrigo, R.; Rodriguez, S.; Romani, P.; Bermejo, M.R.; Sarris, E.T.; Schenk, P.; Schmitt, B.; Schmitz, N.; Schulze-Makuch, D.; Schwingenschuh, K.; Selig, A.; Sicardy, B.; Soderblom, L.; Spilker, L.J.; Stam, D.; Steele, A.; Stephan, K.; Strobel, D.F.; Szego, K.; Szopa,

    2009-01-01

    TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds 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. TandEM 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). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfi??re) and possibly several landing probes to be delivered through the atmosphere. ?? Springer Science + Business Media B.V. 2008.

  15. 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.

  16. Microstructure evolution during pressureless sintering of bulk oxide ceramics

    Directory of Open Access Journals (Sweden)

    Karel Maca

    2009-06-01

    Full Text Available The author’s experience concerning the infl uence of the choice of different pressureless heating schedules on the fi nal microstructure of oxide ceramic materials is summarized in the paper. Alumina, ceria, strontium titanate, as well as tetragonal (3 mol% Y2O3 and cubic (8 mol% Y2O3 zirconia were cold isostatically pressed or injection moulded and pressureless sintered with different heating schedules – namely with Constant-Rate of Heating with different dwell temperatures (CRH, with Rate-Controlled Sintering (RCS and with Two-Step Sintering (TSS. It was examined whether some of these three sintering schedules, with the same fi nal density achieved, can lead to a decrease of the grain size of sintered ceramics. The results showed that only TSS (and only for selected materials brought significant decrease of the grain size.

  17. Recent developments in transparent spinel ceramic and composite windows

    Science.gov (United States)

    Bayya, Shyam; Villalobos, Guillermo; Kim, Woohong; Sanghera, Jas; Chin, Geoff; Hunt, Michael; Sadowski, Bryan; Miklos, Fritz; Aggarwal, Ishwar

    2013-09-01

    The U.S. Naval Research Laboratory has pioneered the development of sintering processes for making highly transparent optical ceramics. For example, we have demonstrated the fabrication of record low absorption loss spinel as an exit window for High Energy Laser systems and rare earth doped Y2O3 and Lu2O3 for solid-state ceramic lasers. We have also developed thick spinel windows for submarine photonic masts and predicted the performance of an imaging system using testing and modeling. More recently, we have developed a novel approach of hot pressing where a transparent ceramic is produced in the net shape without requiring post polishing. This technology will result in significant cost savings associated with polishing the final optical element. We are also developing motheye structures on spinel surface to provide rugged anti-reflective solutions. We had earlier identified a Barium GalloGermanate (BGG) glass with matching index and expansion coefficient to spinel. We had demonstrated fabrication of a laminated dome for the Joint Air to Ground Missile (JAGM) program and the technology was transitioned to industry. We have pushed this technology further by developing a BGG glass - spinel ceramic transparent micro-composite, which can be processed well below spinel sintering temperatures. To address the relatively lower strength of BGG glass compared with spinel, we developed an ion-exchange process and achieved strengths up to 450 MPa. This paper gives a summary of our recent findings.

  18. CRYSTALLINE CERAMIC WASTE FORMS: REFERENCE FORMULATION REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, K.; Fox, K.; Marra, J.

    2012-05-15

    The research conducted in this work package is aimed at taking advantage of the long term thermodynamic stability of crystalline ceramics to create more durable waste forms (as compared to high level waste glass) in order to reduce the reliance on engineered and natural barrier systems. Durable ceramic waste forms that incorporate a wide range of radionuclides have the potential to broaden the available disposal options and to lower the storage and disposal costs associated with advanced fuel cycles. Assemblages of several titanate phases have been successfully demonstrated to incorporate radioactive waste elements, and the multiphase nature of these materials allows them to accommodate variation in the waste composition. Recent work has shown that they can be successfully produced from a melting and crystallization process. The objective of this report is to explain the design of ceramic host systems culminating in a reference ceramic formulation for use in subsequent studies on process optimization and melt property data assessment in support of FY13 melter demonstration testing. The waste stream used as the basis for the development and testing is a combination of the projected Cs/Sr separated stream, the Trivalent Actinide - Lanthanide Separation by Phosphorous reagent Extraction from Aqueous Komplexes (TALSPEAK) waste stream consisting of lanthanide fission products, the transition metal fission product waste stream resulting from the transuranic extraction (TRUEX) process, and a high molybdenum concentration with relatively low noble metal concentrations. In addition to the combined CS/LN/TM High Mo waste stream, variants without Mo and without Mo and Zr were also evaluated. Based on the results of fabricating and characterizing several simulated ceramic waste forms, two reference ceramic waste form compositions are recommended in this report. The first composition targets the CS/LN/TM combined waste stream with and without Mo. The second composition targets

  19. LTCC processed CoTi substituted M-type barium ferrite composite with BBSZ glass powder additives for microwave device applications

    Science.gov (United States)

    Wang, Yu; Liu, Yingli; Li, Jie; Liu, Qian; Zhang, Huaiwu; Harris, Vincent. G.

    2016-05-01

    Hexagonal magnetoplumbite ferrites typically have sintering temperatures above 1100∘C in order to stabilize a single phase compound, which is much higher than the melting point of silver leading to device fabrication challenges. Application of low temperature co-fired ceramics (LTCC) technologies may prove effective in decreasing the sintering temperature of hexagonal ferrites. Ferrite powders combined with glass frit powder is an effective pathway to lowering the sintering temperature. Here, hexagonal M-type barium ferrite (i.e., Ba(CoTi)1.5Fe9O19) ceramics, combined with BBSZ glass powder as a sintering aid were synthesized. Co and Ti ions where used to substitute for Fe cations in order to modify the magnetic anisotropy field. The density, microstructure, magnetic properties and complex permeability are reported. The BBSZ glass addition was shown to improve the densification and magnetic properties of the barium ferrite. The densification of the BaM ferrite Ba(CoTi)1.5Fe9O19 was further enhanced by the glass additive at low firing temperatures of below 900∘C because of the formation of a liquid phase. Complex permeability of ferrites sintered at 900∘C was also influenced by the BBSZ addition and the resonance frequency was shown to decrease with increased amounts of the glass modifier.

  20. LTCC processed CoTi substituted M-type barium ferrite composite with BBSZ glass powder additives for microwave device applications

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available Hexagonal magnetoplumbite ferrites typically have sintering temperatures above 1100∘C in order to stabilize a single phase compound, which is much higher than the melting point of silver leading to device fabrication challenges. Application of low temperature co-fired ceramics (LTCC technologies may prove effective in decreasing the sintering temperature of hexagonal ferrites. Ferrite powders combined with glass frit powder is an effective pathway to lowering the sintering temperature. Here, hexagonal M-type barium ferrite (i.e., Ba(CoTi1.5Fe9O19 ceramics, combined with BBSZ glass powder as a sintering aid were synthesized. Co and Ti ions where used to substitute for Fe cations in order to modify the magnetic anisotropy field. The density, microstructure, magnetic properties and complex permeability are reported. The BBSZ glass addition was shown to improve the densification and magnetic properties of the barium ferrite. The densification of the BaM ferrite Ba(CoTi1.5Fe9O19 was further enhanced by the glass additive at low firing temperatures of below 900∘C because of the formation of a liquid phase. Complex permeability of ferrites sintered at 900∘C was also influenced by the BBSZ addition and the resonance frequency was shown to decrease with increased amounts of the glass modifier.

  1. 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.

  2. Barium Ferrite Films Grown By Pulsed Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Roesthuis, F.J.G.

    1998-01-01

    Abstract available only. It is known that barium ferrite (BaFe12019) can grow with perpendicular anisotropy on A1203 a single crystal substrate,' but also on an amorphous substrate by using a ZnO buffer.2 Because of its large magnetic anisotropy which can easily overcome the shape anisotropy of the

  3. 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.

  4. 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...

  5. Excitation energies of barium oxide bands measured in flames

    NARCIS (Netherlands)

    Hurk, J. van der; Hollander, Tj.; Alkemade, C.T.J.

    1975-01-01

    Experiments are described that yield additional information about the excitation energy of visible barium oxide bands appearing in flames. Excitation energy differences are derived directly from the ratios of thermal band intensities as a function of temperature and agree with the value calculated f

  6. Third-Order Electric-Field-Induced Dipolar Resonances from Patterned Barium-Strontium-Titanate Thin-Films

    Science.gov (United States)

    Toonen, Ryan; Will Cole, Melanie; Ivill, Mathew; Hirsch, S.; Integrated Electromagnetic Materials Team Team

    2013-03-01

    Using microwave reflection spectroscopy, the complex permittivities of etch-defined, 240 nm thick, [Ba(0.6)Sr(0.4)]TiO(3), thin films were measured over the frequency range of (1 to 4) GHz. The observed electro-acoustic resonances were characterized as a function of extrinsic electric field magnitude, ambient temperature, and sample diameter. The real and imaginary parts of the measured permittivities were fit to frequency-dependent functions derived from the Lorentz oscillator model. From these functions, extracted static dielectric constants were found to display excellent agreement with a closed-form expression derived by calculating third-order nonlinear susceptibility from the Landau-Devonshire-Ginzberg model [R. C. Toonen and M. W. Cole, Appl. Phys. Lett. 100, 222908 (2012)]. By investigating the behavior of these loss mechanisms in response to external stimuli, we have gained insight with respect to how such effects can be reduced or even eliminated. It is also possible that these loss mechanisms could be exploited for the purpose of engineering micro-/nano-electro-mechanical resonators and super-compact high-quality-factor frequency-selective filters. Funding for these efforts was provided by an award from the ARL Director's Research Initiative (FY10-WMR-27).

  7. 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...

  8. Ion Tracks and Microstructures in Barium Titanate Irradiated with Swift Heavy Ions: A Combined Experimental and Computational Study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Weilin; Devanathan, Ramaswami; Sundgren, Christina J.; Ishimaru, Manabu; Sato, Kazuhisa; Varga, Tamas; Manandhar, Sandeep; Benyagoub, Abdenacer

    2013-12-11

    Tetragonally structured BaTiO3 single crystals were irradiated using 635 MeV 238U+ ions to fluences of 1E7, 5E10 and 1.4E12 ions/cm2 at room temperature. Subsequent sample characterizations were performed using ion channeling, x-ray diffraction (XRD), helium ion microscopy, and transmission electron microscopy. The results show that there are lattice relaxation and recovery of pre-existing defects in the irradiated samples. Various structures representing different regimes of electronic and nuclear interactions along the ion track are observed. The track on the surface has an amorphous core of up to ~10 nm in diameter, surrounded by a strained lattice structure. The core size is roughly proportional to the square root of the electronic stopping power. Satellite-like defects around the core are also present. The ring of cubic phase expected to form around the amorphous core does not appear, probably due to a reversible phase transition as confirmed by an in-situ XRD study. Modeling and simulation are also attempted to interpret the data and gain physical insights. We have developed a partial charge model for cubic BaTiO3 that reproduces its lattice constants, elastic constants, and melting temperature. Using the interatomic potential, we have performed molecular dynamics simulations of the irradiation damage in BaTiO3. The results show that an amorphous track of ~1.2 nm in radius forms under thermal energy deposition at dE(T)/dx = 5 keV/nm. At 20 keV/nm, the radius increases to ~4.5 nm with an order of magnitude increase in the number of defects. The simulation also reveals details of the bonding environments and shows that the amorphous zones produced at different dE(T)/dx values have different densities. The combined experimental and computational data suggest that there is a significant interfacial recrystallization of the as-created amorphous cores during the cooling-down stage of thermal spikes.

  9. Crystallization and dielectric properties of lead-free glass-ceramic composites with Gd_2O_3 addition

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Lead-free glass-ceramic composites in barium sodium niobate silica system with Gd2O3 addition were synthesized through melt-casting fol-lowed by controlled crystallization technique. Crystallization and dielectric properties of the Gd2O3 adding glass-ceramic composites were investigated. With the increase in the concentration of Gd2O3, the glass transition temperature and the crystallization temperature of the pre-cursor glass shift towards the higher temperature. The crystallization behavior that occurred ...

  10. Mechanical and dielectric characterization of lead zirconate titanate(PZT)/polyurethane(PU) thin film composite for energy harvesting

    Science.gov (United States)

    Aboubakr, S.; Rguiti, M.; Hajjaji, A.; Eddiai, A.; Courtois, C.; d'Astorg, S.

    2014-04-01

    The Lead Zirconate titanate (PZT) ceramic is known by its piezoelectric feature, but also by its stiffness, the use of a composite based on a polyurethane (PU) matrix charged by a piezoelectric material, enable to generate a large deformation of the material, therefore harvesting more energy. This new material will provide a competitive alternative and low cost manufacturing technology of autonomous systems (smart clothes, car seat, boat sail, flag ...). A thin film of the PZT/PU composite was prepared using up to 80 vol. % of ceramic. Due to the dielectric nature of the PZT, inclusions of this one in a PU matrix raises the permittivity of the composite, on other hand this latter seems to decline at high frequencies.

  11. Ternary Phase Diagrams that Relate to the Plutonium Immobilization Ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B b; Krikorian, O H; Vance, E R; Stewart, M W

    2001-01-01

    The plutonium immobilization ceramic consists primarily of a pyrochlore titanate phase of the approximate composition Ca{sub 0.97}Hf{sub 0.17}Pu{sub 0.22}U{sub 0.39}Gd{sub 0.24} Ti{sub 2}O{sub 7}. In this study, a series of ternary phase diagrams was constructed to evaluate the relationship of various titanate phases (e.g., brannerite, zirconolite-2M, zirconolite-4M, and perovskite) to pyrochlore titanates, usually in the presence of excess TiO{sub 2} (rutile), and at temperatures in the vicinity of 1350 C. To facilitate the studies, U, Th, and Ce were used as surrogates for Pu in a number of the phase diagrams in addition to the use of Pu itself. The effects of impurity oxides, Al{sub 2}O{sub 3} and MgO, were also studied on pyrochlore (Gd{sub 2}Ti{sub 2}O{sub 7}) and zirconolite (CaHfTi{sub 2}O{sub 7}) mixtures. Either electron microprobe (at Lawrence Livermore National Laboratory) or quantitative SEM-EDS (at Australian Nuclear Science and Technology Organization) were used to evaluate the compositions of the phases.

  12. Advanced ceramic coating development for industrial/utility gas turbines

    Science.gov (United States)

    Vogan, J. W.; Stetson, A. R.

    1982-01-01

    A program was conducted with the objective of developing advanced thermal barrier coating (TBC) systems. Coating application was by plasma spray. Duplex, triplex and graded coatings were tested. Coating systems incorporated both NiCrAly and CoCrAly bond coats. Four ceramic overlays were tested: ZrO2.82O3; CaO.TiO2; 2CaO.SiO2; and MgO.Al2O3. The best overall results were obtained with a CaO.TiO2 coating applied to a NiCrAly bond coat. This coating was less sensitive than the ZrO2.8Y2O3 coating to process variables and part geometry. Testing with fuels contaminated with compounds containing sulfur, phosphorus and alkali metals showed the zirconia coatings were destabilized. The calcium titanate coatings were not affected by these contaminants. However, when fuels were used containing 50 ppm of vanadium and 150 ppm of magnesium, heavy deposits were formed on the test specimens and combustor components that required frequent cleaning of the test rig. During the program Mars engine first-stage turbine blades were coated and installed for an engine cyclic endurance run with the zirconia, calcium titanate, and calcium silicate coatings. Heavy spalling developed with the calcium silicate system. The zirconia and calcium titanate systems survived the full test duration. It was concluded that these two TBC's showed potential for application in gas turbines.

  13. Grain growth kinetics in liquid-phase-sintered zinc oxide-barium oxide ceramics

    Science.gov (United States)

    Yang, Sung-Chul; German, Randall M.

    1991-01-01

    Grain growth of ZnO in the presence of a liquid phase of the ZnO-BaO system has been studied for temperatures from 1300 to 1400 C. The specimens were treated in boiling water and the grains were separated by dissolving the matrix phase in an ultrasonic bath. As a consequence 3D grain size measurements were possible. Microstructural examination shows some grain coalescence with a wide range of neck size ratios and corresponding dihedral angles, however, most grains are isolated. Lognormal grain size distributions show similar shapes, indicating that the growth mechanism is invariant over this time and temperature. All regressions between G exp n and time for n = 2 and 3 proved statistically significant. The rate constants calculated with the growth exponent set to n = 3 are on the same order of magnitude as in metallic systems. The apparent activation energy for growth is estimated between 355 and 458 kJ/mol.

  14. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    Science.gov (United States)

    Sliney, Harold E.; Dellacorte, Christopher

    1994-01-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  15. Mechanical properties of ceramic-polymer nanocomposites

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Nano crystalline powders of Barium Sodium Niobate (BNN with the composition Ba3–2x Na4+x R Nb10 O30 with (R stands for rare earth = 0, x = 0 have been prepared by conventional ceramic technique. Barium Sodium Niobate can form a wide range of solid solutions, incorporating rare earth and alkali, alkaline earth elements with different compositions. The powder belonged to tungsten bronze type structure with tetragonal symmetry and lattice constants a = b = 1.2421 nm and c = 0.3903 nm. XRD (X-ray Diffraction SEM (Scanning Electron Microscope and AFM (Atomic Force Microscope studies revealed that the particle size is in the nanometer range. Composites are prepared by mixing powders of BNN with polystyrene at different volume fractions of the BNN. Melt mixing technique is carried out in a Brabender Plasticoder at a rotor speed of 60 rpm (rotations per minute for composite preparation. Mechanical properties such as stress-strain behavior, Young’s modulus, tensile strength, strain at break etc. are evaluated. Addition of filler enhances the mechanical properties of the polymer such as Young’s modulus and tensile strength. The composites showed the trend of perfect adhesion between the filler and the polymer. The filler particles are distributed relatively uniform fashion in all composites and the particles are almost spherical in shape with irregular boundaries. To explore more carefully the degree of interfacial adhesion between the two phases, the results are analyzed by using models featuring adhesion parameter. The experimental results are compared with theoretical predictions.

  16. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  17. Ceramic laser materials

    Science.gov (United States)

    Ikesue, Akio; Aung, Yan Lin

    2008-12-01

    The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material - polycrystalline ceramic - can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

  18. Preparação e caracterização microestrutural de cerâmicas ferroelétricas de Ba0,77Ca0,23TiO3 Preparation and microstructural characterization of Ba0.77Ca0.23TiO3 ferroelectric ceramics

    Directory of Open Access Journals (Sweden)

    T. Mazon

    2004-06-01

    Full Text Available Cerâmicas de titanato de bário e cálcio com composição Ba0.77Ca0.23TiO3 (BCT23 foram produzidas usando o método de síntese por reação de estado sólido. Um estudo sistemático de temperatura e tempo de calcinação foi realizado com o objetivo de se determinar as condições experimentais ótimas para a obtenção da fase única BCT23. Observou-se a presença das fases BaTiO3 e CaTiO3 para os pós calcinados em temperaturas inferiores a 1200 ºC e tempo de até 12 horas. Um aumento na temperatura para 1250 ºC leva a formação da fase BCT23. Os pós calcinados a 1250 ºC foram prensados uniaxialmente em diferentes condições e sinterizados a 1450 ºC / 4h. Verificou-se que o método utilizado para a preparação dos compactos influenciou na microestrutura e densidade relativa das cerâmicas. Cerâmicas mais densas foram obtidas a partir da prensagem com pressão uniaxial equivalente a 1x10(7 N/m² dos pós de BCT23 peneirados.Barium calcium titanate ceramics with composition Ba0,77Ca0,23TiO3 (BCT23 were prepared by solid state reaction. A systematic study of temperature and time of calcination was performed aiming to determine the experimental conditions to obtain only BCT23 phase. It was only observed the BaTiO3 and CaTiO3 phases at calcination temperature up to 1200 ºC and time up to 12 h. However, it was possible to obtain the BCT23 phase by increasing the temperature to 1250 ºC for 12 h. The powders calcined at 1250 ºC for 12 h were uniaxially pressed at different conditions and sintered at 1450 ºC / 4h. The method utilized to prepare the compacts influenced on the microstructure and relative density of the ceramics. Denser ceramics were obtained by pressing a BCT23 powder with 1x10(7 N/m².

  19. Dielectric characterization of low-loss calcium strontium titanate fibers produced by laser floating zone technique for wireless communication

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, F. [Department of Physics and I3N, University of Aveiro, 3810-193, Aveiro (Portugal); Polytechnic Institute of Coimbra, 3000-271, Coimbra (Portugal); Valente, M.A.; Costa, L.C.; Costa, F.M. [Department of Physics and I3N, University of Aveiro, 3810-193, Aveiro (Portugal)

    2014-09-15

    Wireless communication technology assisted to a huge development during the last two decades, responding to the growing demand for small size and low weight devices such as cell phones and global positioning systems. The need for miniaturization and higher autonomy resulted in the development of new dielectric oxide ceramics with very specific properties, to be applied as dielectric resonators in filters, oscillators, and antennas. Some crucial properties as a high quality factor, high dielectric constant, and near zero temperature coefficient of resonant frequency must be considered during the selection of the appropriate materials. The present work deals with the preparation of calcium titanate (CaTiO{sub 3}), strontium titanate (SrTiO{sub 3}), and calcium strontium titanate (Ca{sub x}Sr{sub 1-x}TiO{sub 3}) fibers produced by laser floating zone (LFZ) technique. Our results show that fibers grown at lower pulling rates exhibit higher ε', for all the studied frequency range, including the microwave region. Moreover, the quality factor is always high envisaging the possibility to include these materials in future wireless device applications. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.