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Sample records for ferroelectric barium titanate

  1. Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)]. E-mail: duo.liu@mail.uh.edu; Chelf, M. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States); White, K.W. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)

    2006-10-15

    The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {l_brace}110{r_brace}{sub pc}<11-bar 0>{sub pc}. The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed.

  2. Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

    International Nuclear Information System (INIS)

    Liu, D.; Chelf, M.; White, K.W.

    2006-01-01

    The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {110} pc pc . The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed

  3. 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.

  4. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

    Science.gov (United States)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

    2009-03-01

    Bi2O3-doped barium zirconate titanate ceramics, Ba1-xBix(Zr0.05Ti0.95)O3, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi3+ substitutes A-site ion, and thereafter with higher Bi3+ content, it enters the B-site sub lattice. Substitution of Bi3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  5. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

    International Nuclear Information System (INIS)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

    2009-01-01

    Bi 2 O 3 -doped barium zirconate titanate ceramics, Ba 1-x Bi x (Zr 0.05 Ti 0.95 )O 3 , have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi 3+ substitutes A-site ion, and thereafter with higher Bi 3+ content, it enters the B-site sub lattice. Substitution of Bi 3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  6. 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.)

  7. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain.

    Science.gov (United States)

    Suzuki, Norihiro; Osada, Minoru; Billah, Motasim; Bando, Yoshio; Yamauchi, Yusuke; Hossain, Shahriar A

    2018-03-27

    Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

  8. A theoretical investigation of the influence of the surface effect on the ferroelectric property of strained barium titanate film

    Science.gov (United States)

    Fang, Chao; Liu, Wei Hua

    2017-07-01

    The influence of the surface effect on the ferroelectric property of strained barium titanate film has been investigated. In this study, based on time-dependent Ginsburg-Landau-Devonshire thermodynamic theory, the surface effects have been simulated by introducing a surface constant, which leads to the strained BaTiO3 film consisting of inner tetragonal core and gradient lattice strain layer. Further, surface effects produce a depolarization field which has a dominant effect on the ferroelectric properties of the films. The spontaneous polarization, dielectric properties and ferroelectric hysteresis loop of BaTiO3 film are calculated under different boundary conditions. Theoretical and experimental results for strained BaTiO3 film are compared and discussed.

  9. Chemical composition and deformation-induced stresses in ferroelectric films of barium-strontium titanate

    International Nuclear Information System (INIS)

    Karmanenko, S.F.; Dedyk, A.I.; Isakov, N.N.; Sakharov, V.I.; Semenov, A.A.; Serenkov, I.T.; Ter-Martirosyan, L.T.

    1999-01-01

    Influence of the ratio of cationic components and inner deformation-induced stresses on critical temperature (T c ) and dielectric characteristics of ferroelectric films Ba x Sr 1-x TiO 3 grown on α-Al 2 O 3 [1012] and LaAlO 3 substrates was studied. Diagnosis by means of ion backscattering permitted ascertaining the deficiency of barium in the films near the surface layer, as well as differences in their structural quality [ru

  10. Dielectric properties of composite based on ferroelectric copolymer of poly(vinylidene fluoride-trifluoroethylene and ferroelectric ceramics of barium lead zirconate titanate

    Directory of Open Access Journals (Sweden)

    A. V. Solnyshkin

    2017-10-01

    Full Text Available A study of dielectric properties of composite films on the base of poly(vinylidene fluoride-trifluoroethylene copolymer P(VDF-TrFE and ferroelectric ceramics of barium lead zirconate titanate (BPZT solid solution is presented in this work. The composite films containing up to 50 vol.% of BPZT grains with size ∼1μm were prepared by the solvent cast method. Frequency dependences of real and imaginary components of the complex permittivity were determined. The concentration dependence of the dielectric constant was discussed.

  11. Origin of thermally stable ferroelectricity in a porous barium titanate thin film synthesized through block copolymer templating

    Directory of Open Access Journals (Sweden)

    Norihiro Suzuki

    2017-07-01

    Full Text Available A porous barium titanate (BaTiO3 thin film was chemically synthesized using a surfactant-assisted sol-gel method in which micelles of amphipathic diblock copolymers served as structure-directing agents. In the Raman spectrum of the porous BaTiO3 thin film, a peak corresponding to the ferroelectric tetragonal phase was observed at around 710 cm−1, and it remained stable at much higher temperature than the Curie temperature of bulk single-crystal BaTiO3 (∼130 °C. Measurements revealed that the ferroelectricity of the BaTiO3 thin film has high thermal stability. By analyzing high-resolution transmission electron microscope images of the BaTiO3 thin film by the fast Fourier transform mapping method, the spatial distribution of stress in the BaTiO3 framework was clearly visualized. Careful analysis also indicated that the porosity in the BaTiO3 thin film introduced anisotropic compressive stress, which deformed the crystals. The resulting elongated unit cell caused further displacement of the Ti4+ cation from the center of the lattice. This displacement increased the electric dipole moment of the BaTiO3 thin film, effectively enhancing its ferro(piezoelectricity.

  12. 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.

  13. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi{sub 2}O{sub 3}-doped barium zirconium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India); Sreenivas, K, E-mail: omprakasht@hotmail.co [Department of Physics and Astrophysics, University of Delhi- 110007 (India)

    2009-03-21

    Bi{sub 2}O{sub 3}-doped barium zirconate titanate ceramics, Ba{sub 1-x}Bi{sub x}(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi{sup 3+} substitutes A-site ion, and thereafter with higher Bi{sup 3+} content, it enters the B-site sub lattice. Substitution of Bi{sup 3+} ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  14. Improved dielectric and ferroelectric properties of Mn doped barium zirconium titanate (BZT) ceramics for energy storage applications

    Science.gov (United States)

    Sangwan, Kanta Maan; Ahlawat, Neetu; Kundu, R. S.; Rani, Suman; Rani, Sunita; Ahlawat, Navneet; Murugavel, Sevi

    2018-06-01

    Lead free Mn doped barium zirconium titanate ceramic of composition BaZr0.045 (MnxTi1-x)0.955O3 (x = 0.00, 0.01, 0.02) were prepared by solid state reaction method. Tetragonal perovskite structure was confirmed by Rietveld refinement of X-ray diffraction pattern. Analysis of Scanning electron microscope (SEM) micrographs revealed that addition of Mn up to a certain limit accelerates grain growth of BZT ceramic. Static dielectric constant was successfully extended up to high frequencies with an appreciable decrease in dielectric loss about 70% for Mn doped BZT ceramics. The experimental data fitted with Curie Weiss Law and Power Law confirmed first order transition and diffusive behavior of the investigated system. The shifting of Curie temperature (Tc) from 387 K to 402 K indicated tendency for sustained ferroelectricity in doped BZMT ceramics. High value of percentage temperature coefficient of capacitance TCC >10% near Tc was observed for all the compositions and increases with Mn content in pure BZT. At room temperature, BZT modified ceramic corresponding to x = 0.01 composition shows better values of remnant polarization (Pr = 5.718 μC/cm2), saturation polarization (Ps = 14.410 μC/cm2), low coercive field (Ec = 0.612 kV/cm), and highest value of Pr/Ps = 0.396.

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

    International Nuclear Information System (INIS)

    Zapata-Navarro, A.; Marquez-Herrera, A.; Cruz-Jauregui, M.P.; Calzada, M.L.

    2005-01-01

    In this work, we present the variation of the ferroelectric properties of Ba 1-x Sr x TiO 3 films deposited on Pt/TiO 2 /SiO 2 /Si substrates by RF co-sputtering with 0≤x≤1. The co-sputtering was done using a single magnetron with BaTiO 3 /SrTiO 3 targets in a pie mosaics configuration. Smooth and uniform films were obtained using the same conditions of growth and annealing temperature. The X-ray diffraction and EDS results show that the processes were managed to obtain crystalline materials with x from 0 to 1. The behaviour of P-E loops suggests that the ferroelectric properties of the films were tuned by changing the concentration of the cation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Navarro, A.; Marquez-Herrera, A. [CICATA-IPN, Km. 14.5 Carretera Tampico-Puerto Ind. Altamira, Altamira Tamaulipas 89600 (Mexico); Cruz-Jauregui, M.P. [CCMC-UNAM, Km. 107 Carretera Tijuana-Ensenada, Ensenada B.C. 22800 (Mexico); Calzada, M.L. [ICMM (CSIC) Madrid, Cantoblanco Madrid 28049 (Spain)

    2005-08-01

    In this work, we present the variation of the ferroelectric properties of Ba{sub 1-x}Sr{sub x}TiO{sub 3} films deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates by RF co-sputtering with 0{<=}x{<=}1. The co-sputtering was done using a single magnetron with BaTiO{sub 3}/SrTiO{sub 3} targets in a pie mosaics configuration. Smooth and uniform films were obtained using the same conditions of growth and annealing temperature. The X-ray diffraction and EDS results show that the processes were managed to obtain crystalline materials with x from 0 to 1. The behaviour of P-E loops suggests that the ferroelectric properties of the films were tuned by changing the concentration of the cation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

    Roč. 49, č. 25 (2016), č. článku 255307. ISSN 0022-3727 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : ferroelectric domain patterns * electro-optical materials * digital holographic microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/25/255307

  18. Barium titanate inverted opals-synthesis, characterization, and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Soten, I.; Miguez, H.; Yang, S.M.; Petrov, S.; Coombs, N.; Tetreault, N.; Ozin, G.A. [Toronto Univ., ON (Canada). Dept. of Chemistry; Matsuura, N.; Ruda, H.E. [Toronto Univ., ON (Canada). Dept. of Metallurgy and Materials Science

    2002-01-01

    The engineering of cubic or tetragonal polymorphs of nanocrystalline barium titanate inverted opals has been achieved by thermally induced transformations. Optical characterization demonstrated photonic crystal behavior of the opals. The tuning of the ferroelectric-paraelectric transition around the Curie temperature is shown in this paper. (orig.)

  19. Freeze cast porous barium titanate for enhanced piezoelectric energy harvesting

    Science.gov (United States)

    Roscow, J. I.; Zhang, Y.; Kraśny, M. J.; Lewis, R. W. C.; Taylor, J.; Bowen, C. R.

    2018-06-01

    Energy harvesting is an important developing technology for a new generation of self-powered sensor networks. This paper demonstrates the significant improvement in the piezoelectric energy harvesting performance of barium titanate by forming highly aligned porosity using freeze casting. Firstly, a finite element model demonstrating the effect of pore morphology and angle with respect to poling field on the poling behaviour of porous ferroelectrics was developed. A second model was then developed to understand the influence of microstructure-property relationships on the poling behaviour of porous freeze cast ferroelectric materials and their resultant piezoelectric and energy harvesting properties. To compare with model predictions, porous barium titanate was fabricated using freeze casting to form highly aligned microstructures with excellent longitudinal piezoelectric strain coefficients, d 33. The freeze cast barium titanate with 45 vol.% porosity had a d 33  =  134.5 pC N‑1 compared to d 33  =  144.5 pC N‑1 for dense barium titanate. The d 33 coefficients of the freeze cast materials were also higher than materials with uniformly distributed spherical porosity due to improved poling of the aligned microstructures, as predicted by the models. Both model and experimental data indicated that introducing porosity provides a large reduction in the permittivity () of barium titanate, which leads to a substantial increase in energy harvesting figure of merit, , with a maximum of 3.79 pm2 N‑1 for barium titanate with 45 vol.% porosity, compared to only 1.40 pm2 N‑1 for dense barium titanate. Dense and porous barium titanate materials were then used to harvest energy from a mechanical excitation by rectification and storage of the piezoelectric charge on a capacitor. The porous barium titanate charged the capacitor to a voltage of 234 mV compared to 96 mV for the dense material, indicating a 2.4-fold increase that was similar to that

  20. Influence of Bias on the Friction Imaging of Ferroelectric Domains in Single Crystal Barium Titanate Energy Storage Materials

    Directory of Open Access Journals (Sweden)

    Lan Chen

    2014-01-01

    Full Text Available The friction imaging of newlycleaved surface domains of single crystal BaTiO3 energy storage materials under both positive and negative voltage bias is investigated by scanning force microscope. When the bias was applied and reversed, three regions with different brightness and contrast in friction image indicated different response to the biases: the friction image of domain A displayed a great change in brightness while domains B and C displayed only a very small change. Possible mechanisms of the interesting phenomena originating from different static force between different charged tip and the periodical array of surface charges inside the inplane domains were proposed. These results provide a new method for the determination of the polarization direction for the domain parallel to the surface and may be useful in the investigation of ferroelectric energy storage materials, especially the relationship between the polarization direction of domain and the bias.

  1. Barium zirconate-titanate/barium calcium-titanate ceramics via sol-gel process: novel high-energy-density capacitors

    International Nuclear Information System (INIS)

    Puli, Venkata Sreenivas; Kumar, Ashok; Scott, J F; Katiyar, Ram S; Chrisey, Douglas B; Tomozawa, M

    2011-01-01

    Lead-free barium zirconate-titanate/barium calcium-titanate, [(BaZr 0.2 Ti 0.80 )O 3 ] 1-x -[(Ba 0.70 Ca 0.30 )TiO 3 ] x (x = 0.10, 0.15, 0.20) (BZT-BCT) ceramics with high dielectric constant, low dielectric loss and moderate electric breakdown field were prepared by the sol-gel synthesis technique. X-ray diffraction patterns revealed tetragonal crystal structure and this was further confirmed by Raman spectra. Well-behaved ferroelectric hysteresis loops and moderate polarizations (spontaneous polarization, P s ∼ 3-6 μC cm -2 ) were obtained in these BZT-BCT ceramics. Frequency-dependent dielectric spectra confirmed that ferroelectric diffuse phase transition (DPT) exists near room temperature. Scanning electron microscope images revealed monolithic grain growth in samples sintered at 1280 deg. C. 1000/ε versus (T) plots revealed ferroelectric DPT behaviour with estimated γ values of ∼1.52, 1.51 and 1.88, respectively, for the studied BZT-BCT compositions. All three compositions showed packing-limited breakdown fields of ∼47-73 kV cm -1 with an energy density of 0.05-0.6 J cm -3 for thick ceramics (>1 mm). Therefore these compositions might be useful in Y5V-type capacitor applications.

  2. Barium zirconate-titanate/barium calcium-titanate ceramics via sol-gel process: novel high-energy-density capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Puli, Venkata Sreenivas; Kumar, Ashok; Scott, J F; Katiyar, Ram S [SPECLAB, Department of Physics, University of Puerto Rico, San Juan, PR 00936 (Puerto Rico); Chrisey, Douglas B; Tomozawa, M, E-mail: rkatiyar@uprrp.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180-3590 (United States)

    2011-10-05

    Lead-free barium zirconate-titanate/barium calcium-titanate, [(BaZr{sub 0.2}Ti{sub 0.80})O{sub 3}]{sub 1-x}-[(Ba{sub 0.70}Ca{sub 0.30})TiO{sub 3}]{sub x} (x = 0.10, 0.15, 0.20) (BZT-BCT) ceramics with high dielectric constant, low dielectric loss and moderate electric breakdown field were prepared by the sol-gel synthesis technique. X-ray diffraction patterns revealed tetragonal crystal structure and this was further confirmed by Raman spectra. Well-behaved ferroelectric hysteresis loops and moderate polarizations (spontaneous polarization, P{sub s} {approx} 3-6 {mu}C cm{sup -2}) were obtained in these BZT-BCT ceramics. Frequency-dependent dielectric spectra confirmed that ferroelectric diffuse phase transition (DPT) exists near room temperature. Scanning electron microscope images revealed monolithic grain growth in samples sintered at 1280 deg. C. 1000/{epsilon} versus (T) plots revealed ferroelectric DPT behaviour with estimated {gamma} values of {approx}1.52, 1.51 and 1.88, respectively, for the studied BZT-BCT compositions. All three compositions showed packing-limited breakdown fields of {approx}47-73 kV cm{sup -1} with an energy density of 0.05-0.6 J cm{sup -3} for thick ceramics (>1 mm). Therefore these compositions might be useful in Y5V-type capacitor applications.

  3. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-31

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

  4. 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...

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

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Lavrinenko, Andrei

    2013-01-01

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

  6. Mechanical and Microstructural Evaluation of Barium Strontium Titanate Thin Films for Improved Antenna Performance and Reliability

    National Research Council Canada - National Science Library

    Hubbard, C

    1999-01-01

    Ferroelectric barium strontium titanate (Ba(1-x)SrxTiO3 BSTO) films of 1-micron nominal thickness were deposited on single crystals of sapphire and electroded substrates at substrate temperatures varying from 30 deg C to 700 deg C...

  7. Impurities in barium titanate posistor ceramics

    Czech Academy of Sciences Publication Activity Database

    Korniyenko, S. M.; Bykov, I. P.; Glinchuk, M. J.; Laguta, V. V.; Belous, A. G.; Jastrabík, Lubomír

    2000-01-01

    Roč. 239, - (2000), s. 1209-1218 ISSN 0015-0193 Institutional research plan: CEZ:AV0Z1010914 Keywords : barium titanate phase transition * ESR * positive temperature coefficient of resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.547, year: 2000

  8. Barium titanate coated with magnesium titanate via fused salt method and its dielectric property

    International Nuclear Information System (INIS)

    Chen Renzheng; Cui Aili; Wang Xiaohui; Li Longtu

    2003-01-01

    Barium titanate fine particles were coated homogeneously with magnesium titanate via the fused salt method. The thickness of the magnesium titanate film is 20 nm, as verified by TEM and XRD. The mechanism of the coating is that: when magnesium chloride is liquated in 800 deg. C, magnesium will replace barium in barium titanate, and form magnesium titanate film on the surface of barium titanate particles. Ceramics sintered from the coated particles show improved high frequency ability. The dielectric constant is about 130 at the frequency from 1 to 800 MHz

  9. Barium Titanate Nanoparticles for Biomarker Applications

    International Nuclear Information System (INIS)

    Matar, O; Hondow, N S; Brydson, R M D; Milne, S J; Brown, A P; Posada, O M; Wälti, C; Saunders, M; Murray, C A

    2015-01-01

    A tetragonal crystal structure is required for barium titanate nanoparticles to exhibit the nonlinear optical effect of second harmonic light generation (SHG) for use as a biomarker when illuminated by a near-infrared source. Here we use synchrotron XRD to elucidate the tetragonal phase of commercially purchased tetragonal, cubic and hydrothermally prepared barium titanate (BaTiO 3 ) nanoparticles by peak fitting with reference patterns. The local phase of individual nanoparticles is determined by STEM electron energy loss spectroscopy (EELS), measuring the core-loss O K-edge and the Ti L 3 -edge energy separation of the t 2g , e g peaks. The results show a change in energy separation between the t 2g and e g peak from the surface and core of the particles, suggesting an intraparticle phase mixture of the barium titanate nanoparticles. HAADF-STEM and bright field TEM-EDX show cellular uptake of the hydrothermally prepared BaTiO 3 nanoparticles, highlighting the potential for application as biomarkers. (paper)

  10. Relaxor properties of barium titanate crystals grown by Remeika method

    Science.gov (United States)

    Roth, Michel; Tiagunov, Jenia; Dul'kin, Evgeniy; Mojaev, Evgeny

    2017-06-01

    Barium titanate (BaTiO3, BT) crystals have been grown by the Remeika method using both the regular KF and mixed KF-NaF (0.6-0.4) solvents. Typical acute angle "butterfly wing" BT crystals have been obtained, and they were characterized using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy), conventional dielectric and acoustic emission methods. A typical wing has a triangular plate shape which is up to 0.5 mm thick with a 10-15 mm2 area. The plate has a (001) habit and an atomically smooth outer surface. Both K+ and F- solvent ions are incorporated as dopants into the crystal lattice during growth substituting for Ba2+ and O2- ions respectively. The dopants' distribution is found to be inhomogeneous, their content being almost an order of magnitude higher (up to 2 mol%) at out surface of the plate relatively to the bulk. A few μm thick surface layer is formed where a multidomain ferroelectric net is confined between two≤1 μm thick dopant-rich surfaces. The layer as a whole possess relaxor ferroelectric properties, which is apparent from the appearance of additional broad maxima, Tm, in the temperature dependence of the dielectric permittivity around the ferroelectric phase transition. Intense acoustic emission responses detected at temperatures corresponding to the Tm values allow to observe the Tm shift to lower temperatures at higher frequencies, or dispersion, typical for relaxor ferroelectrics. The outer surface of the BT wing can thus serve as a relaxor thin film for various electronic application, such as capacitors, or as a substrate for BT-based multiferroic structure. Crystals grown from KF-NaF fluxes contain sodium atoms as an additional impurity, but the crystal yield is much smaller, and while the ferroelectric transition peak is diffuse it does not show any sign of dispersion typical for relaxor behavior.

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

    International Nuclear Information System (INIS)

    Kessel, Markus Franz

    2012-01-01

    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 3 single crystals has been studied by means of 18 O 2 / 16 O 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 pressure and temperature. The

  12. 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.

  13. Microwave assisted synthesis and characterization of barium titanate nanoparticles for multi layered ceramic capacitor applications.

    Science.gov (United States)

    Thirumalai, Sundararajan; Shanmugavel, Balasivanandha Prabu

    2011-01-01

    Barium titanate is a common ferroelectric electro-ceramic material having high dielectric constant, with photorefractive effect and piezoelectric properties. In this research work, nano-scale barium titanate powders were synthesized by microwave assisted mechano-chemical route. Suitable precursors were ball milled for 20 hours. TGA studies were performed to study the thermal stability of the powders. The powders were characterized by XRD, SEM and EDX Analysis. Microwave and Conventional heating were performed at 1000 degrees C. The overall heating schedule was reduced by 8 hours in microwave heating thereby reducing the energy and time requirement. The nano-scale, impurity-free and defect-free microstructure was clearly evident from the SEM micrograph and EDX patterns. LCR meter was used to measure the dielectric constant and dielectric loss values at various frequencies. Microwave heated powders showed superior dielectric constant value with low dielectric loss which is highly essential for the fabrication of Multi Layered Ceramic Capacitors.

  14. Dielectric response, functionality and energy storage in epoxy nanocomposites: Barium titanate vs exfoliated graphite nanoplatelets

    International Nuclear Information System (INIS)

    Patsidis, A.C.; Kalaitzidou, K.; Psarras, G.C.

    2012-01-01

    Barium titanate/epoxy and exfoliated graphite nanoplatelets/epoxy nanocomposites were prepared and studied varying the filler content. Morphological characteristics were examined via scanning electron microscopy, while structural changes occurring in barium titanate as a function of temperature were investigated by means of X-ray diffraction. Broadband dielectric spectroscopy was employed for determining the dielectric response of the prepared systems. Based on the conducted analysis it was found that three relaxation processes are present in the spectra of the examined materials. From the slower to the faster one, these are interfacial polarization, glass to rubber transition of the polymer matrix, and rearrangement of polar side groups of the polymer chain. Systems' functionality and energy storing efficiency were assessed in terms of dielectric reinforcing function. Finally, the energy density of all systems was evaluated. Composite systems with embedded graphite nanoplatelets exhibit higher energy storing efficiency, while thermally induced structural changes in ferroelectric particles provide functional behavior to barium titanate composites. -- Graphical abstract: Systems' functionality, electrical relaxations and energy storing efficiency were assessed in terms of dielectric permittivity, electric modulus and dielectric reinforcing function (G). Further, the energy density (U) of all systems was evaluated. Composite systems with embedded graphite nanoplatelets exhibit higher energy storing efficiency, while thermally induced structural changes in ferroelectric particles provide functional behavior to barium titanate composites. Highlights: ► Relaxation phenomena were found to be present in all studied systems. ► Two processes emanate from the polymer matrix (α-mode and β-mode). ► Systems' electrical heterogeneity gives rise to interfacial polarization. ► BaTiO 3 /epoxy composites exhibit functional behavior due to structural changes. ► x

  15. Deposition barium titanate (BaTiO3) doped lanthanum with chemical solution deposition

    International Nuclear Information System (INIS)

    Iriani, Y.; Nurhadi, N.; Jamaludin, A.

    2016-01-01

    Deposition of Barium Titanate (BaTiO 3 ) thin films used Chemical Solution Deposition (CSD) method and prepared with spin coater. BaTiO 3 is doped with lanthanum, 1%, 2%, and 3%. The thermal process use annealing temperature 900°C and holding time for 3 hours. The result of characterization with x-ray diffraction (XRD) equipment show that the addition of La 3+ doped on Barium Titanate caused the change of angle diffraction.The result of refine with GSAS software shows that lanthanum have been included in the structure of BaTiO 3 . Increasing mol dopant La 3+ cause lattice parameter and crystal volume become smaller. Characterization result using Scanning Electron Microscopy (SEM) equipment show that grain size (grain size) become smaller with increasing mole dopant (x) La 3+ . The result of characterization using Sawyer Tower methods show that all the samples (Barium Titanante and Barium Titanate doped lanthanum) are ferroelectric material. Increasing of mole dopant La 3+ cause smaller coercive field and remanent polarization increases. (paper)

  16. Properties of barium strontium titanate at millimeter wave frequencies

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-24

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Rare earth doped Barium Titanate (BaTiO_3) 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 BaTiO_3 (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 BaTiO_3 downshifted the Curie temperature (T_C). Transition temperature also known as Curie temperature, T_C where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO_3, Er-doped BaTiO_3, Sm-doped BaTiO_3, Nd-doped BaTiO_3 and Ce-doped BaTiO_3 had been proved to increase and the transition temperature or also known as T_C also lowered down to room temperature as for all the RE doped BaTiO_3 except for Er-doped BaTiO_3.

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

    International Nuclear Information System (INIS)

    Uehara, Y.; Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C.

    1997-01-01

    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 2,3 absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features

  19. 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.

  20. Fabrication and properties of yttrium doped barium titanate film by RF sputtering

    International Nuclear Information System (INIS)

    Igarashi, H.; Yuasa, M.; Okazaki, K.

    1985-01-01

    Semiconductive barium titanate films were fabricated by RF sputtering on fused quartz, alumina and barium titanate ceramic substrates using barium titanate ceramic with a small amount of yttria as a target. The films on the barium titanate substrates turned blue color and showed a small PTC effect by heat-treating at 1000 0 C in the air after deposition at the substrate temperature of 600 0 C

  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. Direct large-scale synthesis of perovskite barium strontium titanate nano-particles from solutions

    International Nuclear Information System (INIS)

    Qi Jianquan; Wang Yu; Wan Pingchen; Long Tuli; Chan, Helen Lai Wah

    2005-01-01

    This paper reports a wet chemical synthesis technique for large-scale fabrication of perovskite barium strontium titanate nano-particles near room temperature and under ambient pressure. The process employs titanium alkoxide and alkali earth hydroxides as starting materials and involves very simple operation steps. Particle size and crystallinity of the particles are controllable by changing the processing parameters. Observations by X-ray diffraction, scanning electron microscopy and transmission electron microscopy TEM indicate that the particles are well-crystallized, chemically stoichiometric and ∼50nm in diameter. The nanoparticles can be sintered into ceramics at 1150 deg. C and show typical ferroelectric hysteresis loops

  3. Ferroelectric devices using lead zirconate titanate (PZT) nanoparticles.

    Science.gov (United States)

    Paik, Young Hun; Kojori, Hossein Shokri; Kim, Sung Jin

    2016-02-19

    We successfully demonstrate the synthesis of lead zirconate titanate nanoparticles (PZT NPs) and a ferroelectric device using the synthesized PZT NPs. The crystalline structure and the size of the nanocrystals are studied using x-ray diffraction and transmission electron microscopy, respectively. We observe PZT NPs and this result matches dynamic light scattering measurements. A solution-based low-temperature process is used to fabricate PZT NP-based devices on an indium tin oxide substrate. The fabricated ferroelectric devices are characterized using various optical and electrical measurements and we verify ferroelectric properties including ferroelectric hysteresis and the ferroelectric photovoltaic effect. Our approach enables low-temperature solution-based processes that could be used for various applications. To the best of our knowledge, this low-temperature solution processed ferroelectric device using PZT NPs is the first successful demonstration of its kind.

  4. Pressure-assisted sintering of high purity barium titanate

    NARCIS (Netherlands)

    van den Cruijsem, S.; Varst, van der P.G.T.; With, de G.; Bortzmeyer, D.; Boussuge, M.; Chartier, Th.; Hausonne, J.M.; Mocellin, A.; Rousset, A.; Thevenot, F.

    1997-01-01

    The dielectric behaviour of High Purity Barium titanate (HPB) ceramics is strongly dependent on the grain size and porosity. For applications, control of grain size and porosity is required. Pressure-assisted sintering techniques at relatively low temperatures meet these requirements. In this study,

  5. The permittivity and refractive index measurements of doped barium titanate (BT-BCN)

    Science.gov (United States)

    Meeker, Michael A.; Kundu, Souvik; Maurya, Deepam; Kang, Min-Gyu; Sosa, Alejandro; Mudiyanselage, Rathsara R. H. H.; Clavel, Michael; Gollapudi, Sreenivasulu; Hudait, Mantu K.; Priya, Shashank; Khodaparast, Giti A.

    2017-11-01

    While piezoelectric- ferroelectric materials offer great potential for nonvolatile random access memory, most commonly implemented ferroelectrics contain lead which imposes a challenge in meeting environmental regulations. One promising candidate for lead-free, ferroelectric material based memory is (1 - x) BaTiO3 - xBa(Cu1 / 3 Nb2 / 3) O3 (BT-BCN), x = 0.025 . The samples studied here were grown on a Si substrate with an HfO2 buffer layer, thereby preventing the interdiffusion of BT-BTCN into Si. This study provides further insight into the physical behavior of BT-BCN that will strengthen the foundation for developing switching devices. The sample thicknesses ranged from 1.5 to 120 nm, and piezoelectric force microscopy was employed in order to understand the local ferroelectric behaviors. Dielectric constant as a function of frequency demonstrated enhanced frequency dispersion indicating the polar nature of the composition. The relative permittivity was found to change significantly with varying bias voltage and exhibited a tunability of 82%. The difference in the peak position during up and down sweeps is due to the presence of the spontaneous polarization. Furthermore, reflectometry was performed to determine the refractive index of samples with differing thicknesses. Our results demonstrate that refractive indices are similar to that of barium titanate. This is a promising result indicating that improved ferroelectric properties are obtained without compromising the optical properties.

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

    International Nuclear Information System (INIS)

    Wang Guiqin; Chen Xiaodong; Duan Yuping; Liu Shunhua

    2008-01-01

    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

  7. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    International Nuclear Information System (INIS)

    Simoes, A.Z.; Moura, F.; Onofre, T.B.; Ramirez, M.A.; Varela, J.A.; Longo, E.

    2010-01-01

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

    CERN Document Server

    Merchant, Serena

    2014-01-01

    Ferroelectric physics is a theory on ferroelectric phase transition for explaining various related phenomena, which is different from dielectric physics. Ferroelectric materials are important functional materials for various applications such as NVRAMs, high energy density capacitors, actuators, MEMs, sonar sensors, microphones and scanning electron microscopes (SEM). This book investigates the dielectric, ferroelectric and energy storage properties of barium zirconate-titanate/barium calcium-titanate (BZT-BCT) based ceramic for high energy density capacitors. It also compares the energy storage capabilities of ceramic powders with polymer-ceramic nanocomposites; and discusses dielectric properties of ferroelectricity in composition distributions.

  9. Characterization and properties of barium bismuth titanate

    Directory of Open Access Journals (Sweden)

    Jelena D. Bobić

    2009-06-01

    Full Text Available BaBi4Ti4O15 (BBiT was prepared from stoichiometric amounts of BaTiO3 (BT and Bi4Ti3O12 (BIT obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. BBiTceramics were sintered at 1100°C, 1110°C and 1120°C for 1 h without pre-calcination step. The formation of phase and crystal structure of BT, BIT and BBiT were verified using X-ray analysis. The morphology of obtained powders and microstructure were examined using scanning electron microscopy. The electrical properties of sintered samples were carried out and BBiT shows behaviour typical for relaxor ferroelectrics and dielectric constant at room temperature is approximately 93.

  10. 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.

  11. 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

  12. Barium strontium titanate powders prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Brankovic, G.; Brankovic, Z.; Goes, M.S.; Paiva-Santos, C.O.; Cilense, M.; Varela, J.A.; Longo, E.

    2005-01-01

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

  13. Formation of barium strontium titanate powder by solid state reaction using different calcination temperatures

    International Nuclear Information System (INIS)

    Teoh Wah Tzu; Ahmad Fauzi Mohd Noor; Zainal Arifin Ahmad

    2002-01-01

    The unique electrical properties of large permittivity in Barium Strontium Titanate have been widely used to make capacitors; it can be produced by solid state reaction. In this study, the mixture of Barium Carbonate, Strontium Carbonate and Titanium Dioxide was calcined at 500 degree C, 1000 degree C, 1100 degree C , 1150 degree C, 1200 degree C, 1250 degree C and 1300 degree C. The results of the phases change in each stage were investigated via X ay Diffraction. The results show that the formation of Barium Strontium Titanate started at 1100 degree C with the presence of other phases. The mixture is fully reacted to form Barium Strontium Titanate at 1150 degree C. Only Barium Strontium Titanate was formed as the calcination temperature was set higher. (Author)

  14. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining

    International Nuclear Information System (INIS)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R.

    2009-01-01

    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 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)

  15. Texturing of sodium bismuth titanate-barium titanate ceramics by templated grain growth

    Science.gov (United States)

    Yilmaz, Huseyin

    2002-01-01

    Sodium bismuth titanate modified with barium titanate, (Na1/2Bi 1/2)TiO3-BaTiO3 (NBT-BT), is a candidate lead-free piezoelectric material which has been shown to have comparatively high piezoelectric response. In this work, textured (Na1/2Bi1/2)TiO 3-BaTiO3 (5.5mol% BaTiO3) ceramics with pc (where pc denotes the pseudocubic perovskite cell) orientation were fabricated by Templated Grain Growth (TGG) or Reactive Templated Grain Growth (RTGG) using anisotropically shaped template particles. In the case of TGG, molten salt synthesized SrTiO3 platelets were tape cast with a (Na1/2Bi1/2)TiO3-5.5mol%BaTiO3 powder and sintered at 1200°C for up to 12 hours. For the RTGG approach, Bi4Ti3O12 (BiT) platelets were tape cast with a Na2CO3, Bi2O3, TiO 2, and BaCO3 powder mixture and reactively sintered. The TGG approach using SrTiO3 templates gave stronger texture along [001] compared to the RTGG approach using BiT templates. The textured ceramics were characterized by X-ray and electron backscatter diffraction for the quality of texture. The texture function was quantified by the Lotgering factor, rocking curve, pole figures, inverse pole figures, and orientation imaging microscopy. Electrical and electromechanical property characterization of randomly oriented and pc textured (Na1/2Bi1/2)TiO 3-5.5 mol% BaTiO3 rhombohedral ceramics showed 0.26% strain at 70 kV/cm, d33 coefficients over 500 pC/N have been obtained for highly textured samples (f ˜ 90%). The piezoelectric coefficient from Berlincourt was d33 ˜ 200 pC/N. The materials show considerable hysteresis. The presence of hysteresis in the unipolar-electric field curve is probably linked to the ferroelastic phase transition seen in the (Na 1/2Bi1/2)TiO3 system on cooling from high temperature at ˜520°C. The macroscopic physical properties (remanent polarization, dielectric constant, and piezoelectric coefficient) of random and textured ([001] pc) rhombohedral perovskites were estimated by linear averaging of single

  16. Barium titanate nanocomposite capacitor FY09 year end report.

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Tyler E.; DiAntonio, Christopher Brian; Yang, Pin; Chavez, Tom P.; Winter, Michael R.; Monson, Todd C.; Roesler, Alexander William; Fellows, Benjamin D.

    2009-11-01

    This late start RTBF project started the development of barium titanate (BTO)/glass nanocomposite capacitors for future and emerging energy storage applications. The long term goal of this work is to decrease the size, weight, and cost of ceramic capacitors while increasing their reliability. Ceramic-based nanocomposites have the potential to yield materials with enhanced permittivity, breakdown strength (BDS), and reduced strain, which can increase the energy density of capacitors and increase their shot life. Composites of BTO in glass will limit grain growth during device fabrication (preserving nanoparticle grain size and enhanced properties), resulting in devices with improved density, permittivity, BDS, and shot life. BTO will eliminate the issues associated with Pb toxicity and volatility as well as the variation in energy storage vs. temperature of PZT based devices. During the last six months of FY09 this work focused on developing syntheses for BTO nanoparticles and firing profiles for sintering BTO/glass composite capacitors.

  17. Microwave absorption properties of barium titanate/epoxide resin composites

    International Nuclear Information System (INIS)

    Chen Xiaodong; Wang Guiqin; Duan Yuping; Liu Shunhua

    2007-01-01

    Nano-barium titanate (BT) was prepared by a sol-gel method. The prepared powders were characterized by x-ray powder diffraction and transmission electron microscopy. The complex relative dielectric permittivity (ε = ε' - jε-prime) and magnetic permeability (μ = μ' - jμ-prime) of the BT powders were measured in the frequency range 8 ∼ 18 GHz. The BT/epoxide resin (EP) composite with different volume contents was investigated. The effects of thickness on the BT/EP composite were studied. It was found that an optimum thickness and contents of the absorber can yield the maximum reflection loss which could be obtained over a broad frequency region in the X and Ku bands. Our results indicate that BT could be a promising microwave absorption material

  18. 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.

  19. 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.

  20. 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.

  1. AB initio energetics of lanthanum substitution in ferroelectric bismuth titanate

    International Nuclear Information System (INIS)

    Shah, S.H.

    2012-01-01

    Density functional theory based electronic structure calculations play a vital role in understanding, controlling and optimizing physical properties of materials at microscopic level. In present study system of interest is bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/)/(BIT) which has wide range of applications such as a high temperature piezoelectric and one of the best material for memory devices. However, it also suffers from serious issues such as oxygen vacancies which degrade its performance as a memory element and piezoelectric material. In this context, the bulk and defect properties of orthorhombic bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/) and bismuth lanthanum titanate (Bi/sub 3.25/La/sub 0.75/Ti/sub 3/O/sub 12/)/(BLT, x=0.75) were investigated by using first principles calculations and atomistic thermodynamics. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies were computed. The study improves understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It was found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions for the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls and therefore a decrease in their concentration is beneficial. (orig./A.B.)

  2. Electrooptic and piezoelectric measurements in photorefractive barium titanate and strontium barium niobate

    International Nuclear Information System (INIS)

    Ducharme, S.; Feinberg, J.; Neurgaonkar, R.R.

    1987-01-01

    The authors measured the low-frequency (''unclamped'') electrooptic and piezoelectric coefficients in undoped BaTiO/sub 3/ and Sr/sub x/Ba/sub 1-x/Nb/sub 2/O/sub 6/ (chi - 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurement is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of of the applied field and independent of its frequency in the range of 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO/sub 3/ single crystals are r/sub 13/ = 19.5 +- 1 pm/V and r/sub 33/ = 97 +- 7 pm/V, and for strontium barium niobate are r/sub 13/ = 47 +- 5 pm/V and r/sub 33/ = 235 +- 21 pm/V, all measured at a wavelength of 514.5 nm and at T = 23 0 C. For the barium titanate samples the measured Pockels coefficient r/sub c/ identical to r/sub 33/ - (n/sub 1//n/sub 3/)/sup 3/r/sub 13/ = 79 +- 6 pm/V in good agreement with the value r/sub c/ = 76 +- 7 pm/V computed from the above values of r/sub 13/ and r/sub 33/, where n/sub 1/ and n/sub 3/ are the ordinary and extraordinary indexes of refraction, respectively. The measured piezoelectric coefficient is d/sub 23/ = +28.7 +- 2 pm/V for barium titanate, and is d/sub 23/ = +24.6 +- 2 pm/V for strontium barium niobate. They also measured the photoreflective coupling of two optical beams in the crystals, and they show that the dependence of the coupling strength on beam polarization is in fair agreement with the measured values of the Pockels coefficients

  3. Molecular ferroelectrics: where electronics meet biology.

    Science.gov (United States)

    Li, Jiangyu; Liu, Yuanming; Zhang, Yanhang; Cai, Hong-Ling; Xiong, Ren-Gen

    2013-12-28

    In the last several years, we have witnessed significant advances in molecular ferroelectrics, with the ferroelectric properties of molecular crystals approaching those of barium titanate. In addition, ferroelectricity has been observed in biological systems, filling an important missing link in bioelectric phenomena. In this perspective, we will present short historical notes on ferroelectrics, followed by an overview of the fundamentals of ferroelectricity. The latest developments in molecular ferroelectrics and biological ferroelectricity will then be highlighted, and their implications and potential applications will be discussed. We close by noting molecular ferroelectric as an exciting frontier between electronics and biology, and a number of challenges ahead are also described.

  4. 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.

  5. 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.

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

    DEFF Research Database (Denmark)

    Majkut, Marta

    This thesis presents an in-situ three-dimensional study of the grain-scale response of a prototypical piezoelectric ceramic, barium titanate (BT), to an exernally applied electric field. Piezoceramics take advantage of the coupling of electrical and mechanical energies for use in sensors and actu......This thesis presents an in-situ three-dimensional study of the grain-scale response of a prototypical piezoelectric ceramic, barium titanate (BT), to an exernally applied electric field. Piezoceramics take advantage of the coupling of electrical and mechanical energies for use in sensors...

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

    International Nuclear Information System (INIS)

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

    2009-01-01

    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 deg. C.

  8. Barium Titanate Photonic Crystal Electro-Optic Modulators for Telecommunication and Data Network Applications

    Science.gov (United States)

    Girouard, Peter D.

    The microwave, optical, and electro-optic properties of epitaxial barium titanate thin films grown on (100) MgO substrates and photonic crystal electro-optic modulators fabricated on these films were investigated to demonstrate the applicability of these devices for telecommunication and data networks. The electrical and electro-optical properties were characterized up to modulation frequencies of 50 GHz, and the optical properties of photonic crystal waveguides were determined for wavelengths spanning the optical C band between 1500 and 1580 nm. Microwave scattering parameters were measured on coplanar stripline devices with electrode gap spacings between 5 and 12 mum on barium titanate films with thicknesses between 230 and 680 nm. The microwave index and device characteristic impedance were obtained from the measurements. Larger (lower) microwave indices (impedances) were obtained for devices with narrower electrode gap spacings and on thicker films. Thinner film devices have both lower index mismatch between the co-propagating microwave and optical signals and lower impedance mismatch to a 50O system, resulting in a larger predicted electro-optical 3 dB bandwidth. This was experimentally verified with electro-optical frequency response measurements. These observations were applied to demonstrate a record high 28 GHz electro-optic bandwidth measured for a BaTiO3 conventional ridge waveguide modulator having 1mm long electrodes and 12 mum gap spacing on a 260nm thick film. The half-wave voltage and electro-optic coefficients of barium titanate modulators were measured for films having thicknesses between 260 and 500 nm. The half-wave voltage was directly measured at low frequencies using a polarizer-sample-compensator-analyzer setup by over-driving waveguide integrated modulators beyond their linear response regime. Effective in-device electro-optic coefficients were obtained from the measured half-wave voltages. The effective electro-optic coefficients were

  9. an oxalate-peroxide complex used in the preparation of doped barium titanate

    NARCIS (Netherlands)

    van der Gijp, S.; Winnubst, Aloysius J.A.; Verweij, H.

    1998-01-01

    A method is described for the preparation of homogeneously doped barium titanate, which can be applied in non-linear dielectric elements. Ba and Ti salts are dissolved, mixed with hydrogen peroxide and added to a solution of ammonium oxalate, resulting in the formation of an insoluble peroxo-oxalate

  10. Dielectric properties and vacancy-like defects in plasma-sprayed barium titanate.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Čížek, J.; Sedláček, J.; Lukáč, František

    2017-01-01

    Roč. 100, č. 7 (2017), s. 2972-2983 ISSN 0002-7820 Institutional support: RVO:61389021 Keywords : barium titanate * plasma spraying * vacancies Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass OBOR OECD: Ceramic s Impact factor: 2.841, year: 2016

  11. Raman analysis of ferroelectric switching in niobium-doped lead zirconate titanate thin films

    International Nuclear Information System (INIS)

    Ferrari, P.; Ramos-Moore, E.; Guitar, M.A.; Cabrera, A.L.

    2014-01-01

    Characteristic Raman vibration modes of niobium-doped lead zirconate titanate (PNZT) are studied as a function of ferroelectric domain switching. The microstructure of PNZT is characterized by scanning electron microscopy and X-ray diffraction. Ferroelectric switching is achieved by applying voltages between the top (Au) and bottom (Pt) electrodes, while acquiring the Raman spectra in situ. Vibrational active modes associated with paraelectric and ferroelectric phases are identified after measuring above and below the ferroelectric Curie temperature, respectively. Changes in the relative intensities of the Raman peaks are observed as a function of the switching voltage. The peak area associated with the ferroelectric modes is analyzed as a function of the applied voltage within one ferroelectric polarization loop, showing local maxima around the coercive voltage. This behavior can be understood in terms of the correlation between vibrational and structural properties, since ferroelectric switching modifies the interaction between the body-centered atom (Zr, Ti or Nb) and the Pb–O lattice. - Highlights: • Electric fields induce structural distortions on ferroelectric perovskites. • Ferroelectric capacitor was fabricated to perform hysteresis loops. • Raman analysis was performed in situ during ferroelectric switching. • Raman modes show hysteresis and inflections around the coercive voltages. • Data can be understood in terms of vibrational–structural correlations

  12. Dynamic fatigue on repolarization of lead zirconate-titanate base ceramics with various ferroelectric hardness

    International Nuclear Information System (INIS)

    Gavrilyachenko, V.G.; Semenchev, A.F.; Sklyarova, E.N.; Kuznetsova, E.M.

    2006-01-01

    One studied experimentally changes of the residual polarization in lead zirconate-titanate base ceramics with various ferroelectric hardness under the effect of a strong varying field. The twinning and untwinning of crystallites accompanying repolarization is assumed to be the basic mechanism of propagation of the crystalline structure defects governing the fatigue rates of the ferroelectric-soft ceramics. In ferroelectric-hard ceramics crystallites the stable configurations of mechanical twins, the result of the secondary twinning, are formed when the hysteresis loop is formed. At repolarization in the mentioned structures one observes no motion of the twin boundaries, and the fatigue rates are low ones [ru

  13. Radiation losses in microwave K_u region by conducting pyrrole/barium titanate and barium hexaferrite based nanocomposites

    International Nuclear Information System (INIS)

    Kaur, Talwinder; Kumar, Sachin; Narang, S.B.; Srivastava, A.K.

    2016-01-01

    Nanocomposites of substituted barium hexaferrite and barium titanate embedded in a polymer were synthesized via emulsion polymerization. The study was performed by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, electron spin resonance spectroscopy, a vibrating sample magnetometer and a vector network analyzer. It is found that maximum radiation loss occur at 16.09 GHz (−14.23 dB) frequency owing to the combined effect of conducting polymer, suitable dielectric and magnetic material. This suggests that prepared material is suitable for radiation losses. Micro structural study reveals the presence of all the phases of the compounds comprises composite. Benzene ring absorption band (at 1183 cm"−"1) in FT-IR spectra illustrates the presence of polymer. Surface morphology reveals the presence of array of particles encapsulated by the polymer. - Highlights: • Composites having polymer, barium titanate and hexaferrite have been successfully prepared. • Effective radiation absorption and losses have been achieved. • Magnetic properties have made an impact on shielding effectiveness.

  14. Radiation losses in microwave K{sub u} region by conducting pyrrole/barium titanate and barium hexaferrite based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Talwinder [Department of Physics, Lovely Professional University, Phagwara 144411 (India); Kumar, Sachin [Department of Chemistry, Guru Nanak Dev University, Amritsar 143005 (India); Narang, S.B. [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India); Srivastava, A.K., E-mail: srivastava_phy@yahoo.co.in [Department of Physics, Lovely Professional University, Phagwara 144411 (India)

    2016-12-15

    Nanocomposites of substituted barium hexaferrite and barium titanate embedded in a polymer were synthesized via emulsion polymerization. The study was performed by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, electron spin resonance spectroscopy, a vibrating sample magnetometer and a vector network analyzer. It is found that maximum radiation loss occur at 16.09 GHz (−14.23 dB) frequency owing to the combined effect of conducting polymer, suitable dielectric and magnetic material. This suggests that prepared material is suitable for radiation losses. Micro structural study reveals the presence of all the phases of the compounds comprises composite. Benzene ring absorption band (at 1183 cm{sup −1}) in FT-IR spectra illustrates the presence of polymer. Surface morphology reveals the presence of array of particles encapsulated by the polymer. - Highlights: • Composites having polymer, barium titanate and hexaferrite have been successfully prepared. • Effective radiation absorption and losses have been achieved. • Magnetic properties have made an impact on shielding effectiveness.

  15. 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)

  16. Observation of potential barriers on barium strontium titanate PTCR ceramics by electrostatic force microscopy

    International Nuclear Information System (INIS)

    Manfredini, J.P.; Paulin Filho, P.I.; Gheno, S.M.

    2011-01-01

    A composition of PTCR ceramic based in barium titanate with isovalent replacement of part of barium by strontium using lanthanum and manganese as additives was investigated. The transition temperature, typical of these materials, was shifted below the room temperature by the presence of strontium, whose behavior was detected by tests of DC resistivity and impedance spectroscopy. The observation of potential barriers at grain boundaries was possible through the technique of electrostatic force microscopy (EFM). The results also showed the presence of space charges in regions inside grains, possibly at subgrain boundaries. (author)

  17. Mobility of ferroelastic domain walls in barium titanate

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří

    2007-01-01

    Roč. 349, - (2007), s. 49-54 ISSN 0015-0193 R&D Projects: GA ČR GA202/06/0411 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric and ferroelastic domains * BaTiO 3 * Ginzburg-Landau theory * mobility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.427, year: 2007

  18. Characterization of individual barium titanate nanorods and their assessment as building blocks of new circuit architectures

    International Nuclear Information System (INIS)

    Zagar, Kristina; Recnik, Aleksander; Ceh, Miran; Hernandez-Ramirez, Francisco; Morante, Joan Ramon; Prades, Joan Daniel

    2011-01-01

    In this work, we report on the integration of individual BaTiO 3 nanorods into simple circuit architectures. Polycrystalline BaTiO 3 nanorods were synthesized by electrophoretic deposition (EPD) of barium titanate sol into aluminium oxide (AAO) templates and subsequent annealing. Transmission electron microscopy (TEM) observations revealed the presence of slabs of hexagonal polymorphs intergrown within cubic grains, resulting from the local reducing atmosphere during the thermal treatment. Electrical measurements performed on individual BaTiO 3 nanorods revealed resistivity values between 10 and 100 Ω cm, which is in good agreement with typical values reported in the past for oxygen-deficient barium titanate films. Consequently the presence of oxygen vacancies in their structure was indirectly validated. Some of these nanorods were tested as proof-of-concept humidity sensors. They showed reproducible responses towards different moisture concentrations, demonstrating that individual BaTiO 3 nanorods may be integrated in complex circuit architectures with functional capacities.

  19. Multiscale Study of Barium Titanate Nanostructures and Nanocomposites

    Science.gov (United States)

    Louis, Lydie

    Advancements in integrated nanoelectronics will continue to require the use of unique materials or systems of materials with diverse functionalities in increasingly confined spaces. Hence, research on finite-dimensional systems strive to unearth and expand the knowledge of fundamental physical properties in certain key materials which exhibit numerous concurrent and exploitable functions. Correspondingly, ferroelectric nanostructures, which particularly display a plethora of complex phenomena, prevalent in countless fields of research, are noteworthy candidates. Presently, however, the assimilation of zero-(0D) and one-dimensional (1D) ferroelectric into micro- or nano-electronics has been lagging, in part due to a lack of applied and fundamental studies but also due to the paucity of synthetic strategies yielding high quality monocrystalline structures. In this work, the problematics of size reduction, which affects many aspects of electronic devices, was addressed. Furthermore, the depolarizing effects associated with finite thickness in ferroelectric nanostructures was investigated in connection with other crucial boundary conditions. The work reported in this dissertation concerned isolated 0D and 1D BaTiO3 nanocrystals and nanocomposites composed of periodic arrays of BaTiO 3 nanowires embedded in a matrix formed by another ferroelectric material. A systematic investigation was conducted for those three types of nanostructures from a quantum mechanical and atomistic perspective using both direct-first-principles and first-principles-derived methods. Using first-principles-based calculations, the structural phase sequences in 0D (cubic-to-tetragonal-to-monoclinic-to-rhombohedral) and 1D (cubic-to-tetragonal-to-orthorhombic-to-monoclinic) BaTiO3 nanoparticles revealed differences from that of the bulk and thin film systems. The monoclinic symmetry found in the 0D compounds, and as for the ground-state of 1D systems, were also affected by size effects and tuned

  20. Structural contribution to the ferroelectric fatigue in lead zirconate titanate ceramics

    Science.gov (United States)

    Hinterstein, M.; Rouquette, J.; Haines, J.; Papet, Ph.; Glaum, J.; Knapp, M.; Eckert, J.; Hoffman, M.

    2014-09-01

    Many ferroelectric devices are based on doped lead zirconate titanate (PZT) ceramics with compositions near the morphotropic phase boundary (MPB), at which the relevant material's properties approach their maximum. Based on a synchrotron x-ray diffraction study of MPB PZT, bulk fatigue is unambiguously found to arise from a less effective field induced tetragonal-to-monoclinic transformation, at which the degradation of the polarization flipping is detected by a less intense and more diffuse anomaly in the atomic displacement parameter of lead. The time dependence of the ferroelectric response on a structural level down to 250 μs confirms this interpretation in the time scale of the piezolectric strain response.

  1. Ferroelastic domain walls in barium titanate - quantitative phenomenological model

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří; Márton, Pavel

    2009-01-01

    Roč. 101, č. 1 (2009), s. 50-62 ISSN 1058-4587 R&D Projects: GA ČR GA202/06/0411; GA ČR(CZ) GD202/05/H003; GA AV ČR 1ET300100401 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric and ferroelastic domains * BaTiO 3 * Ginzburg-Landau theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.329, year: 2009

  2. Improved flexoelectricity in PVDF/barium strontium titanate (BST) nanocomposites

    Science.gov (United States)

    Hu, Xinping; Zhou, Yang; Liu, Jie; Chu, Baojin

    2018-04-01

    The flexoelectric effect of polymers is normally much weaker than that of ferroelectric oxides. In order to improve the flexoelectric response of the poly(vinylidene fluoride) (PVDF) ferroelectric polymer, PVDF/Ba0.67Si0.33TiO3 (BST) nanocomposites were fabricated. BST nanofibers were prepared by the electrospinning method, and the fibers were further surface modified with H2O2 to achieve a stronger interfacial interaction between the fibers and polymer matrix. Due to the high dielectric properties and strong flexoelectric effect of the BST, both dielectric constant and flexoelectric response of the composite with 25 vol. % surface modified BST are 3-4 times higher than those of PVDF. The dependence of the dielectric constant and the flexoelectric coefficient on the composition of the nanocomposites can be fitted by the empirical Yamada model, and the dielectric constant and the flexoelectric coefficient are correlated by a linear relationship. This study provides an approach to enhance the flexoelectric response of PVDF-based polymers.

  3. Structural Contribution to the Ferroelectric Fatigue in Lead Zirconate Titanate (PZT) Ceramics

    OpenAIRE

    Hinterstein , Manuel; Rouquette , Jerome; Haines , J; Papet , Ph; Glaum , Julia; Knapp , Michael; Eckert , J; Hoffman , M

    2014-01-01

    International audience; Many ferroelectric devices are based on doped lead zirconate titanate (PZT) ceramics with compositions near the morphotropic phase boundary (MPB), at which the relevant material's properties approach their maximum. Based on a synchrotron x-ray diffraction study of MPB PZT, bulk fatigue is unambiguously found to arise from a less effective field induced tetragonal-to-monoclinic transformation, at which the degradation of the polarization flipping is detected by a less i...

  4. Dielectric properties of calicum and barium-doped strontium titanate

    Science.gov (United States)

    Tung, Li-Chun

    Dielectric properties of high quality polycrystalline Ca- and Ba-doped SrTiO3 perovskites are studied by means of dielectric constant, dielectric loss and ferroelectric hysteresis measurements. Low frequency dispersion of the dielectric constant is found to be very small and a simple relaxor model may not be able to explain its dielectric behavior. Relaxation modes are found in these samples, and they are all interpreted as thermally activated Bipolar re-orientation across energy barriers. In Sr1- xCaxTiO3 (x = 0--0.3), two modes are found associated with different relaxation processes, and the concentration dependence implies a competition between these processes. In Sr1-xBa xTiO3 (x = 0--0.25), relaxation modes are found to be related to the structural transitions, and the relaxation modes persist at low doping levels (x Barret formula is discussed and two of the well-accepted models, anharmonic oscillator model and transverse Ising model, are found to be equivalent. Both of the Ca and Ba systems can be understood qualitatively within the concept of transverse Ising model.

  5. Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

    Science.gov (United States)

    Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

    2007-08-01

    Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

  6. Microstructure Control of Barium Titanate Grain-oriented Ceramics and Their Piezoelectric Properties

    International Nuclear Information System (INIS)

    Mori, Rintaro; Nakashima, Koichi; Fujii, Ichiro; Wada, Satoshi; Hayashi, Hiroshi; Nagamori, Yoshitaka; Yamamoto, Yuichi

    2011-01-01

    The Barium titanate (BaTiO 3 , BT) [110] grain-oriented ceramics along [110] direction were prepared by a templated grain growth (TGG) method. The [110] oriented BT platelike particles (t-BT) were used as template particles. The relationship between poling treatment program and piezoelectric constant was investigated. The change in the poling conditions did not greatly influence domain size and the piezoelectric constant. The relationship between piezoelectric properties and domain size in BT grain-oriented ceramics was investigated. The smaller domain size was required to increase the piezoelectric constant.

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

    International Nuclear Information System (INIS)

    Remmel, Thomas; Werho, Dennis; Liu, Ran; Chu, Peir

    1998-01-01

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

  8. 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.

  9. Synthesis and colloidal properties of anisotropic hydrothermal barium titanate

    Science.gov (United States)

    Yosenick, Timothy James

    2005-11-01

    Nanoparticles of high dielectric constant materials, especially BaTiO3, are required to achieve decreased layer thickness in multilayer ceramic capacitors (MLCCs). Tabular metal nanoparticles can produce thin metal layers with low surface roughness via electrophoretic deposition (EPD). To achieve similar results with dielectric layers requires the synthesis and dispersion of tabular BaTiO3 nanoparticles. The goal of this study was to investigate the deposition of thin BaTiO3 layers using a colloidal process. The synthesis, interfacial chemistry and colloidal properties of hydrothermal BaTiO3 a model particle system, was investigated. After characterization of the material system particulates were deposited to form thin layers using EPD. In the current study, the synthesis of BaTiO3 has been investigated using a hydrothermal route. TEM and AFM analyses show that the synthesized particles are single crystal with a majority of the particle having a zone axis and {111} large face. The particles have a median thickness of 5.8 +/- 3.1 nm and face diameter of 27.1 +/- 12.3 nm. Particle growth was likely controlled by the formation of {111} twins and the synthesis pH which stabilizes the {111} face during growth. With limited growth in the direction, the particles developed a plate-like morphology. Physical property characterization shows the powder was suitable for further processing with high purity, low hydrothermal defect concentration, and controlled stoichiometry. TEM observations of thermally treated powders indicate that the particles begin to loose the plate-like morphology by 900 °C. The aqueous passivation, dispersion, and doping of nanoscale BaTiO 3 powders was investigated. Passivation BaTiO3 was achieved through the addition of oxalic acid. The oxalic acid selectively adsorbs onto the particle surface and forms a chemically stable 2-3 nm layer of barium oxalate. The negative surface charge of the oxalate effectively passivated the BaTiO3 providing a surface

  10. 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...

  11. 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...

  12. Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics for capacitor applications

    Directory of Open Access Journals (Sweden)

    Zhang Chen

    2018-03-01

    Full Text Available Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

  13. Determination of vanadium in titanate-based ferroelectrics by INAA with discriminating gamma-ray spectrometry

    Czech Academy of Sciences Publication Activity Database

    Kameník, Jan; Dragounová, K.; Kučera, Jan; Bryknar, Z.; Trepakov, Vladimír; Strunga, Vladimír

    2017-01-01

    Roč. 311, č. 2 (2017), s. 1333-1338 ISSN 0236-5731. [1st International Conference on Radioanalytical and Nuclear chemistry (RANC). Budapest, 10.04.2016-15.04.2016] R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : Titanate-based ferroelectrics * Vanadium * INAA * discriminating gamma-ray spectrometry Subject RIV: CB - Analytical Chemistry, Separation; BM - Solid Matter Physics ; Magnetism (FZU-D) OBOR OECD: Analytical chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D) Impact factor: 1.282, year: 2016

  14. Size effect in barium titanate powders synthesized by different hydrothermal methods

    International Nuclear Information System (INIS)

    Sun Weian

    2006-01-01

    The size effect in barium titanate (BaTiO 3 ) was investigated both experimentally and theoretically. Tetragonal BaTiO 3 powders with average sizes from 80 to 420 nm were directly prepared by different hydrothermal methods. The tetragonality of the hydrothermal BaTiO 3 decreased with decreasing particle size, which exhibited a dependence on the synthesis method. A phenomenological model for the size effect was proposed to interpret the experimental observations. The influence of the defects, mainly the lattice hydroxyl, on the size effect was investigated to understand the correlation between the size effect and synthesis condition. The permittivities of BaTiO 3 powder at different particle sizes were calculated, which predicted a maximum permittivity of over 16 000 around the room-temperature critical size of ∼70 nm. The prediction was in good accordance with the experimental data reported recently

  15. Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals

    International Nuclear Information System (INIS)

    Ray, Sugata; Kolen'ko, Yury V; Watanabe, Tomoaki; Yoshimura, Masahiro; Itoh, Mitsuru; Kovnir, Kirill A; Lebedev, Oleg I; Turner, Stuart; Erni, Rolf; Tendeloo, Gustaaf Van; Chakraborty, Tanushree

    2012-01-01

    Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO 3 . The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site and oxygen vacancies and their relative concentrations at the surface and the core of the nanocrystal, which could be controlled by post-synthesis drying and thermal treatments.

  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. Effect of mechanical milling on barium titanate (BaTiO3) perovskite

    Science.gov (United States)

    Singh, Rajan Kumar; Sanodia, Sagar; Jain, Neha; Kumar, Ranveer

    2018-05-01

    Commercial Barium Titanate BaTiO3 (BT) is milled by planetary ball mill in acetone medium using stainless steel bowl & ball for different hours. BT is an important perovskite oxide with structure ABO3. BT has applications in electro-optic devices, energy storing devices such as photovoltaic cells, thermistors, multiceramic capacitors & DRAMs etc. BT is non-toxic & environment friendly ceramic with high dielectric and piezoelectric property so it can be used as the substitute of PZT & PbTiO3. Here, we have investigated the effect of milling time and temperature on particle size and phase transition of BT powder. We used use Raman spectroscopy for studying the spectra of BT; XRD is used for structural study. Intensity (height) of Raman spectra and XRD spectra continuously decrease with increasing the milling hours and width if these spectra increases which indicates, decrease in BT size.

  18. Characterization of barium strontium titanate thin films on sapphire substrate prepared via RF magnetron sputtering system

    Science.gov (United States)

    Jamaluddin, F. W.; Khalid, M. F. Abdul; Mamat, M. H.; Zoolfakar, A. S.; Zulkefle, M. A.; Rusop, M.; Awang, Z.

    2018-05-01

    Barium Strontium Titanate (Ba0.5Sr0.5TiO3) is known to have a high dielectric constant and low loss at microwave frequencies. These unique features are useful for many electronic applications. This paper focuses on material characterization of BST thin films deposited on sapphire substrate by RF magnetron sputtering system. The sample was then annealed at 900 °C for two hours. Several methods were used to characterize the structural properties of the material such as X-ray diffraction (XRD) and atomic force microscopy (AFM). Field emission scanning electron microscopy (FESEM) was used to analyze the surface morphology of the thin film. From the results obtained, it can be shown that the annealed sample had a rougher surface and better crystallinity as compared to as-deposited sample.

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

    CERN Document Server

    Wong, H; Poon, M C

    1999-01-01

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

  20. MIS field effect transistor with barium titanate thin film as a gate insulator

    Energy Technology Data Exchange (ETDEWEB)

    Firek, P., E-mail: pfirek@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Werbowy, A.; Szmidt, J. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland)

    2009-11-25

    The properties of barium titanate (BaTiO{sub 3}, BT) like, e.g. high dielectric constant and resistivity, allow it to find numerous applications in field of microelectronics. In this work silicon metal insulator semiconductor field effect transistor (MISFET) structures with BaTiO{sub 3} (containing La{sub 2}O{sub 3} admixture) thin films in a role of gate insulator were investigated. The films were produced by means of radio frequency plasma sputtering (RF PS) of sintered BaTiO{sub 3} + La{sub 2}O{sub 3} (2 wt.%) target. In the paper transfer and output current-voltage (I-V), transconductance and output conductance characteristics of obtained transistors are presented and discussed. Basic parameters of these devices like, e.g. threshold voltage (V{sub TH}), are determined and discussed.

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

    Directory of Open Access Journals (Sweden)

    Robert Mamazza

    2012-04-01

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

  2. Structure, dielectric and electrical properties of cerium doped barium zirconium titanate ceramics

    International Nuclear Information System (INIS)

    Feng Hongjun; Hou Jungang; Qu Yuanfang; Shan Dan; Yao Guohua

    2012-01-01

    Highlights: ► Rare-earth doped barium zirconate titanate (BZT) ceramics, Ba(Zr 0.25 Ti 0.75 )O 3 + xCeO 2 , (x = 0–1.5 at%) were obtained by a solid state reaction route. ► Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of rare-earth ions affects the growth of the grain and remarkably changes the grain morphology. ► The effect of rare-earth addition to BZT on dielectric and electrical properties is analyzed, demonstrating that the samples with x = 0.4 and x = 0.6 could be semiconducting in air atmosphere. - Abstract: Rare-earth doped barium zirconium titanate (BZT) ceramics, Ba(Zr 0.25 Ti 0.75 )O 3 + xCeO 2 , (x = 0–1.5 at%) were obtained by a solid state reaction route. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data and the lattice parameters were refined by the Rietveld method. It is found that, integrating with the lattice parameters and the distortion of crystal lattice, there is an alternation of substitution preference of cerium ions for the host cations in perovskite lattice. Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of rare-earth ions affects the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on dielectric and electrical properties is analyzed. High values of dielectric tunability are obtained for cerium doped BZT. Especially, the experimental results on the effect of the contents of rare-earth addition on the resistivity of BZT ceramics were investigated, demonstrating that the samples with x = 0.4 and x = 0.6 could be semiconducting in air atmosphere.

  3. Ferroelectric lead magnesium niobate-lead titanate single crystals for ultrasonic hydrophone applications

    International Nuclear Information System (INIS)

    Lau, S.T.; Lam, K.H.; Chan, H.L.W.; Choy, C.L.; Luo, H.S.; Yin, Q.R.; Yin, Z.W.

    2004-01-01

    Ferroelectric lead magnesium niobate-lead titanate (PMN-PT) single crystals with a composition around the rhombohedral-tetragonal morphotropic phase boundary (65 mol% of PMN) were used to fabricate single-element needle-type hydrophones for measuring the spatial and temporal characteristics of medical ultrasonic transducers. PMN-PT single crystal was grown by a modified Bridgman method. Discs (0.5 mm thick) with normal along the direction were cut and then poled by a dc field in the thickness direction. The single crystal has a high relative permittivity (ε r ∼4000) making it appropriate for small area hydrophone applications. Single-element needle-type hydrophones with this material as the sensing element have been fabricated and characterized. The hydrophones have flat frequency response and good receiving sensitivity over certain frequency range in the megahertz region

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

    Directory of Open Access Journals (Sweden)

    Rocca A

    2015-01-01

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

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

    International Nuclear Information System (INIS)

    Jayanthi, S.; Kutty, T.R.N.

    2004-01-01

    Ca-substituted BaTiO 3 with extended homogeneity range upto ∼50 mol% CaTiO 3 have been prepared by three different chemical routes namely carbonate-oxalate (COBCT), gel-carbonate (GCBCT), and gel-to-crystallite conversion (GHBCT) followed by heat treatment above 1150 deg. C. X-ray powder diffraction (XRD) data show continuous decrease in the tetragonal unit cell parameters as well as c 0 /a 0 ratio with CaTiO 3 content, which are in accordance with the substitution of smaller sized Ca 2+ ions at the barium sites. The microstructure as well as the dielectric properties are greatly influenced by the cationic ratio, α=(Ba+Ca)/Ti. The grain size decreases with CaTiO 3 content for the stoichiometric samples (α=1), whereas ultrafine microstructure is observed in the case of off-stoichiometric samples (α>1) for the whole compositional range of CaTiO 3 concentrations. Sharper ε r -T characteristics at lower calcium content and broader ε r -T with decreased ε max , in the higher calcium range are observed in the case of α=1. Whereas nanometer grained ceramics exhibiting diffuse ε r -T characteristics are obtained in the case of α>1. The positive temperature coefficient of resistivity (PTCR) is realized for barium calcium titanate ceramics having 0.3 at.% Sb as the donor dopant for higher CaTiO 3 (typically 30 mol%) containing samples (α=1), indicating that Ca 2+ ions do not behave as acceptors if they were to substitute at the Ti 4+ sites. Whereas the off-stoichiometric (α>1) ceramics retained high resistivity, indicative of the Ti-site occupancy for Ca 2+ in fine grain ceramics

  6. Effect of polarization fatigue on the Rayleigh coefficients of ferroelectric lead zirconate titanate thin films: Experimental evidence and implications

    Science.gov (United States)

    Lou, X. J.; Zhang, H. J.; Luo, Z. D.; Zhang, F. P.; Liu, Y.; Liu, Q. D.; Fang, A. P.; Dkhil, B.; Zhang, M.; Ren, X. B.; He, H. L.

    2014-09-01

    The effect of polarization fatigue on the Rayleigh coefficients of ferroelectric lead zirconate titanate (PZT) thin film was systematically investigated. It was found that electrical fatigue strongly affects the Rayleigh behaviour of the PZT film. Both the reversible and irreversible Rayleigh coefficients decrease with increasing the number of switching cycles. This phenomenon is attributed to the growth of an interfacial degraded layer between the electrode and the film during electrical cycling. The methodology used in this work could serve as an alternative way for evaluating the fatigue endurance and degradation in dielectric properties of ferroelectric thin-film devices during applications.

  7. Ferroelectric mesocrystals of bismuth sodium titanate: formation mechanism, nanostructure, and application to piezoelectric materials.

    Science.gov (United States)

    Hu, Dengwei; Kong, Xingang; Mori, Kotaro; Tanaka, Yasuhiro; Shinagawa, Kazunari; Feng, Qi

    2013-09-16

    Ferroelectric mesocrystals of Bi0.5Na0.5TiO3 (BNT) with [100]-crystal-axis orientation were successfully prepared using a topotactic structural transformation process from a layered titanate H1.07Ti1.73O4·nH2O (HTO). The formation reactions of BNT mesocrystals in HTO-Bi2O3-Na2CO3 and HTO-TiO2-Bi2O3-Na2CO3 reaction systems and their nanostructures were studied by XRD, FE-SEM, TEM, SAED, and EDS, and the reaction mechanisms were given. The BNT mesocrystals are formed by a topotactic structural transformation mechanism in the HTO-Bi2O3-Na2CO3 reaction system and by a combination mechanism of the topotactic structural transformation and epitaxial crystal growth in the HTO-TiO2-Bi2O3-Na2CO3 reaction system, respectively. The BNT mesocrystals prepared by these methods are constructed from [100]-oriented BNT nanocrystals. Furthermore, these reaction systems were successfully applied to the fabrication of [100]-oriented BNT ferroelectric ceramic materials. A BNT ceramic material with a high degree of orientation, high relative density, and small grain size was achieved.

  8. Effect of Semiconductor Element Substitution on the Electric Properties of Barium Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    Garbarz-Glos B.

    2016-06-01

    Full Text Available The investigated ceramics were prepared by a solid-state reaction from simple oxides and carbonates with the use of a mixed oxide method (MOM. The morphology of BaTi0.96Si0.04O3 (BTSi04 ceramics was characterised by means of a scanning electron microscopy (SEM. It was found that Si+4 ion substitution supported the grain growth process in BT-based ceramics. The EDS results confirmed the high purity and expected quantitative composition of the synthesized material. The dielectric properties of the ceramics were also determined within the temperature range (ΔT=130-500K. It was found that the substitution of Si+4 ions had a significant influence on temperature behavior of the real (ε’ and imaginary (ε” parts of electric permittivity as well as the temperature dependence of a.c. conductivity. Temperature regions of PTCR effect (positive temperature coefficient of resistivity were determined for BTSi04 ceramics in the vicinity of structural phase transitions typical for barium titanate. No distinct maximum indicating a low-temperature structural transition to a rhombohedral phase in BTSi04 was found. The activation energy of conductivity was determined from the Arrhenius plots. It was found that substitution of Si ions in amount of 4wt.% caused almost 50% decrease in an activation energy value.

  9. Damage Accumulation and Recovery in Gold-Ion-Irradiated Barium Titanate

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Weilin; Weber, William J.; Thevuthasan, Suntharampillai

    2001-06-04

    Single-crystal barium titanate (BaTiO) wafers were irradiated 60? off the surface normal at 170 and 300 K using 1.0 MeV Au ions over a fluence range from 0.03 to 0.19 ions/nm. Disorder on both the Ba and Ti sublattices has been studied in situ using Rutherford backscattering spectrometry along the <110> axial direction. At these irradiation temperatures, the temperature dependence of disordering is small. The dose for amorphization under these conditions is on the order of 0.5 dpa, which is 50% of that required to amorphize SrTiO under similar conditions. At low damage levels, recovery of disorder is observed at room temperature, suggesting at least one lower temperature recovery stage. For more highly damaged states, two distinct recovery stages have been identified between 420 and 570 K and between 720 and 870 K. The recovery stage between 420 and 570 K is associated with the critical temperature for full amorphization ({approx}550 K) in BaTiO. The higher temperature recovery stage is most likely associated with epitaxial recrystallization.

  10. Damage accumulation and recovery in gold-ion-irradiated barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, W.; Weber, W.J. E-mail: bill.weber@pnl.gov; Thevuthasan, S

    2001-04-01

    Single-crystal barium titanate (BaTiO{sub 3}) wafers were irradiated 60 deg. off the surface normal at 170 and 300 K using 1.0 MeV Au{sup 2+} ions over a fluence range from 0.03 to 0.19 ions/nm{sup 2}. Disorder on both the Ba and Ti sublattices has been studied in situ using Rutherford backscattering spectrometry along the <1 1 0> axial direction. At these irradiation temperatures, the temperature dependence of disordering is small. The dose for amorphization under these conditions is on the order of 0.5 dpa, which is 50% of that required to amorphize SrTiO{sub 3} under similar conditions. At low damage levels, recovery of disorder is observed at room temperature, suggesting at least one lower temperature recovery stage. For more highly damaged states, two distinct recovery stages have been identified between 420 and 570 K and between 720 and 870 K. The recovery stage between 420 and 570 K is associated with the critical temperature for full amorphization ({approx}550 K) in BaTiO{sub 3}. The higher temperature recovery stage is most likely associated with epitaxial recrystallization.

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

    International Nuclear Information System (INIS)

    Yan, Shiguang; Mao, Chaoliang; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin

    2014-01-01

    Relaxation like dielectric anomaly is observed in Y 3+ and Mn 2+ 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.

  12. Synthesis of Barium Titanate from Titanyl Acylate Precursor by Sol-precipitate Method

    International Nuclear Information System (INIS)

    Thandar Win; Kyaw Naing; Khin Mar Tun

    2008-03-01

    Nanometersize barium titanates (BaTiO3:BT) powders can be obtained by sol-precipitate method in the presence of polyoxyethylene (20) sorbiton monooleate (Tween-80) as a polymeric surface modifier in a strong alkaline solution (pH > 13). FT-IR, TG/DTA, SEM and XRD were used to investigate the effects of the surfactant influence on the morphology of the obtained BaTiO3 powders. With adding surfactant, a slower rate of hydrolyzation is observed and the rate of condensation is slower. The addition of Tween-80 surfactant in general leads to the formation of smaller particle size of BaTi)3 (70-100 nm). Without adding surfactant, larger particle size of BaTiO3 (100-200 nm) was obtained. The nanometersize BaTiO3 powders were readily sintered at 1000-1200C. Raman-active modes of tetragonal phase BT were detected from Raman spectra of BaTiO3 between 800 0 C to 1200 0 C.

  13. Low temperature fabrication of barium titanate hybrid films and their dielectric properties

    International Nuclear Information System (INIS)

    Kobayashi, Yoshio; Saito, Hirobumi; Kinoshita, Takafumi; Nagao, Daisuke; Konno, Mikio

    2011-01-01

    A method for incorporating BT nano-crystalline into barium titanate (BT) films is proposed for a low temperature fabrication of high dielectric constant films. BT nanoparticles were synthesized by hydrolysis of a BT complex alkoxide in 2-methoxyethanol (ME)/ethanol cosolvent. As the ME volume fraction in the cosolvent (ME fraction) increased from 0 to 100%, the particle and crystal sizes tended to increase from 13.4 to 30.2 nm and from 15.8 to 31.4 nm, respectively, and the particle dispersion in the solution became more improved. The BT particles were mixed with BT complex alkoxide dissolved in an ME/ethanol cosolvent for preparing a precursor solution that was then spin-coated on a Pt substrate and dried at 150 o C. The dielectric constant of the spin-coated BT hybrid film increased with an increase in the volume fraction of the BT particles in the film. The dissipation factor of the hybrid film tended to decrease with an increase in the ME fraction in the precursor solution. The hybrid film fabricated at a BT fraction of 30% and an ME fraction of 25% attained a dielectric constant as high as 94.5 with a surface roughness of 14.0 nm and a dissipation factor of 0.11.

  14. Measuring the flexoelectric coefficient of bulk barium titanate from a shock wave experiment

    Science.gov (United States)

    Hu, Taotao; Deng, Qian; Liang, Xu; Shen, Shengping

    2017-08-01

    In this paper, a phenomenon of polarization introduced by shock waves is experimentally studied. Although this phenomenon has been reported previously in the community of physics, this is the first time to link it to flexoelectricity, the coupling between electric polarization and strain gradients in dielectrics. As the shock waves propagate in a dielectric material, electric polarization is thought to be induced by the strain gradient at the shock front. First, we control the first-order hydrogen gas gun to impact and generate shock waves in unpolarized bulk barium titanate (BT) samples. Then, a high-precision oscilloscope is used to measure the voltage generated by the flexoelectric effect. Based on experimental results, strain elastic wave theory, and flexoelectric theory, a longitudinal flexoelectric coefficient of the bulk BT sample is calculated to be μ 11 = 17.33 × 10 - 6 C/m, which is in accord with the published transverse flexoelectric coefficient. This method effectively suppresses the majority of drawbacks in the quasi-static and low frequency dynamic techniques and provides more reliable results of flexoelectric behaviors.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-15

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

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

    International Nuclear Information System (INIS)

    Pant, H.C.; Patra, M.K.; Verma, Aditya; Vadera, S.R.; Kumar, N.

    2006-01-01

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

  17. Biocompatible evaluation of barium titanate foamed ceramic structures for orthopedic applications.

    Science.gov (United States)

    Ball, Jordan P; Mound, Brittnee A; Nino, Juan C; Allen, Josephine B

    2014-07-01

    The potential of barium titanate (BT) to be electrically active makes it a material of interest in regenerative medicine. To enhance the understanding of this material for orthopedic applications, the in vitro biocompatibility of porous BT fabricated using a direct foaming technique was investigated. Characterization of the resultant foams yielded an overall porosity between 50 and 70% with average pore size in excess of 30 µm in diameter. A mouse osteoblast (7F2) cell line was cultured with the BT to determine the extent of the foams' toxicity using a LDH assay. After 72 h, BT foams showed a comparable cytotoxicity of 6.4 ± 0.8% to the 8.4 ± 1.5% of porous 45S5 Bioglass®. The in vitro inflammatory response elicited from porous BT was measured as a function of tumor necrosis factor alpha (TNF-α) secreted from a human monocytic leukemia cell line (THP-1). Results indicate that the BT foams do not cause a significant inflammatory response, eliciting a 9.4 ± 1.3 pg of TNF-α per mL of media compared with 20.2 ± 2.3 pg/mL from untreated cells. These results indicate that porous BT does not exhibit short term cytotoxicity and has potential for orthopedic tissue engineering applications. © 2013 Wiley Periodicals, Inc.

  18. Losses in Ferroelectric Materials

    Science.gov (United States)

    Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

    2015-01-01

    Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy

  19. Losses in Ferroelectric Materials.

    Science.gov (United States)

    Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

    2015-03-01

    Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy

  20. 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.

  1. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    International Nuclear Information System (INIS)

    Dutta, Soma; Antony Jeyaseelan, A.; Sruthi, S.

    2014-01-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb 0.92 La 0.08 (Zr 0.52 Ti 0.48 ) 0.98 O 3 was grown preferentially along (111) direction on Pt/SiO 2 /Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm 2 and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d 33,f ) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e 31,f ) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d 33,f and e 31,f coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m 2 respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d 33 value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e 31,f of PLZT film is reported for the first time

  2. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Soma, E-mail: som@nal.res.in; Antony Jeyaseelan, A.; Sruthi, S.

    2014-07-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb{sub 0.92}La{sub 0.08}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.98}O{sub 3} was grown preferentially along (111) direction on Pt/SiO{sub 2}/Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm{sup 2} and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d{sub 33,f}) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e{sub 31,f}) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d{sub 33,f} and e{sub 31,f} coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m{sup 2} respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d{sub 33} value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e{sub 31,f} of PLZT film is reported for the first time.

  3. Obtaining and electrical characterization of silicone/barium titanate composite for variable capacitor applications; Obtencao e caracterizacao eletrica de composito silicone/titanato de bario para aplicacoes em capacitor variavel

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, D.A.; Souza, P.S.S.; Souza, C.P., E-mail: debora.vieira@cear.ufpb.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Centro de Energias Alternativas e Renovaveis. Departamento de Engenharia Eletrica; Menezes, P.C.F. [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    Silicone/barium titanate composites are excellent candidates for applications in the production of electronics components. In this work, silicone/barium titanate composite was obtained for the production of capacitors with variable dielectric distance. The mixture of composite (20% of barium titanate) was performed in a mixer with stem type propellers, at room temperature for 20 minutes. The cure was held in vacuum kiln. After obtaining the composite, was mounted a parallel plate capacitor, using composite as dielectric. The composite obtained was subjected to x-ray diffraction, scanning electron microscopy and capacitive electrical test. The DRX confirms the presence of ceramic charge in composite with the presence of broad peaks of barium titanate and micrographs show the barium titanate particles dispersed in polymer matrix. The capacitance of the sample was approximately 28,7pF. (author)

  4. Preparation and characterization of Grain-Oriented Barium Titanate Ceramics Using Electrophoresis Deposition Method under A High Magnetic Field

    Energy Technology Data Exchange (ETDEWEB)

    Kita, T; Kondo, S; Takei, T; Kumada, N; Nakashima, K; Fujii, I; Wada, S [Material Science and Technology, Interdisciplinary Graduate School of Medical and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510 (Japan); Suzuki, T S; Uchikoshi, T; Sakka, Y [National Institute for materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Miwa, Y; Kawada, S; Kimura, M, E-mail: swada@yamanashi.ac.jp [Murata Manufacturing Co., Ltd. 2288 Ooshinohara, Yasu, Shiga 520-2393 (Japan)

    2011-10-29

    Barium titanate (BaTiO{sub 3}) grain-oriented ceramics were prepared using electrophoresis deposition (EPD) method under high magnetic field of 12 T. First, BaTiO{sub 3} nanoparticles with high c/a ratio of 1.008 and size of 84 nm were prepared by two-step thermal decomposition method with barium titanyl oxalate nanoparticles. Using the BaTiO{sub 3} slurry, BaTiO{sub 3} nanoparticle accumulations were prepared by EPD method under high magnetic field. After binder burnout, the accumulations were sintered and BaTiO{sub 3} grain-oriented ceramics were prepared. Moreover, dielectric properties of their ceramics were investigated

  5. 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}.

  6. In vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate.

    Science.gov (United States)

    Beloti, Márcio M; de Oliveira, Paulo T; Gimenes, Rossano; Zaghete, Maria A; Bertolini, Márcio J; Rosa, Adalberto L

    2006-11-01

    This study was aimed at investigating the in vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT). Osteoblastic cells were obtained from human alveolar bone fragments and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured on P(VDF-TrFE)/BT and expanded polytetrafluoroethylene (e-PTFE--control) membranes in 24-well plates. Cell adhesion and spreading were evaluated at 30 min, and 4 and 24 h. For proliferation assay, cells were cultured for 1, 7, and 10 days. Cell viability was detected by trypan blue at 7 and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 7, 14, and 21 days. Cultures were stained with Alizarin red at 21 days, for detection of mineralized matrix. Data were compared by ANOVA and Student t test. Cell attachment (p = 0.001), cell number (p = 0.001), and ALP activity (p = 0.0001) were greater on P(VDF-TrFE)/BT. Additionally, doubling time was greater on P(VDF-TrFE)/BT (p = 0.03), indicating a decreased proliferation rate. Bone-like nodule formation took place only on P(VDF-TrFE)/BT. The present results showed that both membranes are biocompatible. However, P(VDF-TrFE)/BT presented a better in vitro biocompatibility and allowed bone-like nodule formation. Therefore, P(VDF-TrFE)/BT could be an alternative membrane to be used in guided tissue regeneration.

  7. 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.

  8. Enhanced photoelectrochemical properties of 100 MeV Si8+ ion irradiated barium titanate thin films

    International Nuclear Information System (INIS)

    Solanki, Anjana; Choudhary, Surbhi; Satsangi, Vibha R.; Shrivastav, Rohit; Dass, Sahab

    2013-01-01

    Highlights: ► Effect of 100 MeV Si 8+ ion irradiation on photoelectrochemical (PEC) properties of BaTiO 3 thin films was studied. ► Films were deposited on Indium doped Tin Oxide (ITO) coated glass by sol–gel spin coating technique. ► Optimal irradiation fluence for best PEC response was 5 × 10 11 ion cm −2 . ► Maximum photocurrent density was observed to be 0.7 mA cm −2 at 0.4 V/SCE. ► Enhanced photo-conversion efficiency was due to maximum negative flatband potential, donor density and lowest resistivity. -- Abstract: Effects of high electronic energy deposition on the structure, surface topography, optical property and photoelectrochemical behavior of barium titanate (BaTiO 3 ) thin films were investigated by irradiating films with 100 MeV Si 8+ ions at different ion fluences in the range of 1 × 10 11 –2 × 10 13 ions cm −2 . BaTiO 3 thin films were deposited on indium tin oxide coated glass substrate by sol gel spin coating method. Irradiation induced modifications in the films were analyzed using the results from XRD, SEM, cross sectional SEM, AFM and UV–Vis spectrometry. Maximum photocurrent density of 0.7 mA cm −2 at 0.4 V/SCE and applied bias hydrogen conversion efficiency (ABPE) of 0.73% was observed for BaTiO 3 film irradiated at 5 × 10 11 ions cm −2 , which can be attributed to maximum negative value of the flatband potential and donor density and lowest resistivity

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

    International Nuclear Information System (INIS)

    Siddabattuni, Sasidhar; Schuman, Thomas P.; Dogan, Fatih

    2011-01-01

    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 g measurements. → Composite T 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 ∼6.3 and at a 30 μm thickness achieved a calculated energy density of 4.6 J/cm 3 .

  10. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO_3) ceramics

    International Nuclear Information System (INIS)

    Billah, Masum; Ahmed, A.; Rahman, Md. Miftaur; Mahbub, Rubbayat; Gafur, M. A.; Bashar, M. Shahriar

    2016-01-01

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La_2O_3) doped Barium Titanate (BaTiO_3) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO_3 with 0.3, 0.5 and 0.7 mole% La_2O_3 under different sintering parameters. The raw materials used were La_2O_3 nano powder of ~80 nm grain size and 99.995% purity and BaTiO_3 nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO_3 ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La_2O_3) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La_2O_3 with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La"3"+ concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO_3 ceramics.

  11. Flexoelectricity: strain gradient effects in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wenhui [Department of Physics, Shantou Unversity, Shantou, Guangdong 515063 (China)

    2007-12-15

    Mechanical strain gradient induced polarization effect or flexoelectricity in perovskite-type ferroelectric and relaxor ferroelectric ceramics was investigated. The flexoelectric coefficients measured at room temperature ranged from about 1 {mu} C m{sup -1} for lead zirconate titanate to 100 {mu} C m{sup -1} for barium strontium titanate. Flexoelectric effects were discovered to be sensitive to chemical makeup, phase symmetry, and domain structures. Based on phenomenological discussion and experimental data on flexoelectricity, the present study proposed that mechanical strain gradient field could influence polarization responses in a way analogous to electric field. Flexoelectric coefficients were found to be nonlinearly enhanced by dielectric permittivity and strain gradient. Interfacial mismatch in epitaxial thin films can give rise to high strain gradients, enabling flexoelectric effects to make a significant impact in properly engineered ferroelectric heterostructure systems.

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

    Science.gov (United States)

    Alema, Fikadu Legesse

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

  13. 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)

  14. Influence of KF substitution on the ferroelectric phase transition of lead titanate single crystals studied by Brillouin light scattering

    Directory of Open Access Journals (Sweden)

    Seonhyeop Shin

    2015-06-01

    Full Text Available The elastic properties of KF-substituted perovskite lead titanate (PbTiO3 were investigated by dielectric measurements and Brillouin light scattering. The ferroelectric phase transition occurred at substantially lower temperature due to KF substitution, which was attributed to the modification of the covalency in Pb–O and Ti–O bonds. The longitudinal acoustic (LA mode of KF-substituted PbTiO3 showed a frequency softening in the paraelectric phase, which was accompanied by increasing acoustic damping. This indicated that polarization fluctuations responsible for the acoustic anomalies were enhanced by KF substitution.

  15. High Frequency Magneto Dielectric Effects In Self Assembled Ferrite Ferroelectric Core Shell Nanoparticles

    Science.gov (United States)

    2014-09-10

    ferrimagnetic metals, alloys or oxides and ferroelectrics such as barium titanate (BTO), lead zirconate titanate ( PZT ), and lead magnesium niobate-lead...estimate the magneto-capacitance effect in BTO or PZT films on substrates of ferromagnetic alloys.25 This work is on the observation and theory of MDE...transmission and reflection coefficients were done to estimate the complex permittivity. During the measurements a bias static magnetic field was

  16. 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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 13 C, 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 provide

  17. Dielectric relaxation of barium strontium titanate and application to thin films for DRAM capacitors

    Science.gov (United States)

    Baniecki, John David

    This thesis examines the issues associated with incorporating the high dielectric constant material Barium Strontium Titanate (BSTO) in to the storage capacitor of a dynamic random access memory (DRAM). The research is focused on two areas: characterizing and understanding the factors that control charge retention in BSTO thin films and modifying the electrical properties using ion implantation. The dielectric relaxation of BSTO thin films deposited by metal-organic chemical vapor deposition (MOCVD) is investigated in the time and frequency domains. It is shown that the frequency dispersion of the complex capacitance of BSTO thin films can be understood in terms of a power-law frequency dependence from 1mHz to 20GHz. From the correspondence between the time and frequency domain measurements, it is concluded that the power-law relaxation currents extend back to the nano second regime of DRAM operation. The temperature, field, and annealing dependence of the dielectric relaxation currents are also investigated and mechanisms for the observed power law relaxation are explored. An equivalent circuit model of a high dielectric constant thin film capacitor is developed based on the electrical measurements and implemented in PSPICE. Excellent agreement is found between the experimental and simulated electrical characteristics showing the utility of the equivalent circuit model in simulating the electrical properties of high dielectric constant thin films. Using the equivalent circuit model, it is shown that the greatest charge loss due to dielectric relaxation occurs during the first read after a refresh time following a write to the opposite logic state for a capacitor that has been written to the same logic state for a long time (opposite state write charge loss). A theoretical closed form expression that is a function of three material parameters is developed which estimates the opposite state write charge loss due to dielectric relaxation. Using the closed form

  18. Near-field terahertz imaging of ferroelectric domains in barium titanate

    Czech Academy of Sciences Publication Activity Database

    Berta, Milan; Kadlec, Filip

    2010-01-01

    Roč. 83, 10-11 (2010), 985-993 ISSN 0141-1594 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : singular value decomposition * domain structure imaging * near-field terahertz microscopy * subwavelength resolution Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.006, year: 2010

  19. Preparation and Sound Absorption Properties of a Barium Titanate/Nitrile Butadiene Rubber–Polyurethane Foam Composite with Multilayered Structure

    Science.gov (United States)

    Jiang, Xueliang; Yang, Zhen; Wang, Zhijie; Zhang, Fuqing; You, Feng

    2018-01-01

    Barium titanate/nitrile butadiene rubber (BT/NBR) and polyurethane (PU) foam were combined to prepare a sound-absorbing material with an alternating multilayered structure. The effects of the cell size of PU foam and the alternating unit number on the sound absorption property of the material were investigated. The results show that the sound absorption efficiency at a low frequency increased when decreasing the cell size of PU foam layer. With the increasing of the alternating unit number, the material shows the sound absorption effect in a wider bandwidth of frequency. The BT/NBR-PU foam composites with alternating multilayered structure have an excellent sound absorption property at low frequency due to the organic combination of airflow resistivity, resonance absorption, and interface dissipation. PMID:29565321

  20. Preparation and Sound Absorption Properties of a Barium Titanate/Nitrile Butadiene Rubber–Polyurethane Foam Composite with Multilayered Structure

    Directory of Open Access Journals (Sweden)

    Xueliang Jiang

    2018-03-01

    Full Text Available Barium titanate/nitrile butadiene rubber (BT/NBR and polyurethane (PU foam were combined to prepare a sound-absorbing material with an alternating multilayered structure. The effects of the cell size of PU foam and the alternating unit number on the sound absorption property of the material were investigated. The results show that the sound absorption efficiency at a low frequency increased when decreasing the cell size of PU foam layer. With the increasing of the alternating unit number, the material shows the sound absorption effect in a wider bandwidth of frequency. The BT/NBR-PU foam composites with alternating multilayered structure have an excellent sound absorption property at low frequency due to the organic combination of airflow resistivity, resonance absorption, and interface dissipation.

  1. Preparation and Sound Absorption Properties of a Barium Titanate/Nitrile Butadiene Rubber-Polyurethane Foam Composite with Multilayered Structure.

    Science.gov (United States)

    Jiang, Xueliang; Yang, Zhen; Wang, Zhijie; Zhang, Fuqing; You, Feng; Yao, Chu

    2018-03-22

    Barium titanate/nitrile butadiene rubber (BT/NBR) and polyurethane (PU) foam were combined to prepare a sound-absorbing material with an alternating multilayered structure. The effects of the cell size of PU foam and the alternating unit number on the sound absorption property of the material were investigated. The results show that the sound absorption efficiency at a low frequency increased when decreasing the cell size of PU foam layer. With the increasing of the alternating unit number, the material shows the sound absorption effect in a wider bandwidth of frequency. The BT/NBR-PU foam composites with alternating multilayered structure have an excellent sound absorption property at low frequency due to the organic combination of airflow resistivity, resonance absorption, and interface dissipation.

  2. Upconversion emission study of Er3+/Yb3+ doped barium titanate phosphor prepared by co-precipitation method

    International Nuclear Information System (INIS)

    Mahata, M.K.; Dey, R.; Kumar, K.; Rai, V.K.; Rai, S.B.

    2012-01-01

    In the present work we have successfully synthesized the Er 3+ , Yb 3+ doped barium titanate phosphor via co-precipitation synthesis method. Under 980 nm excitation, tri-color upconversion fluorescence has been observed. The Fourier Transform Infrared measurement was done to check the presence of organic impurities. In order to find out how many photons are involved in each emission band, the variation of UC emission intensity of the codoped phosphor is studied with increase in excitation power. Upconversion emission spectra show that as the annealing temperature of the powder is increased, intensity of red emission decreases and intensity of green emission increases due to the decrease in maximum phonon frequency of the host material. (author)

  3. Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

    Science.gov (United States)

    Ekström, Mattias; Khartsev, Sergiy; Östling, Mikael; Zetterling, Carl-Mikael

    2017-07-01

    4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P- E hysteresis loops measured at room temperature showed maximum 2 P r of 48 μC/cm2, large enough for wide read margins. P- E loops were measurable up to 450°C, with losses limiting measurements above 450°C. The phase-transition temperature was determined to be about 660°C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.

  4. Tunable dielectric properties of Barium Magnesium Niobate (BMN) doped Barium Strontium Titanate (BST) thin films by magnetron sputtering

    Science.gov (United States)

    Alema, Fikadu; Reinholz, Aaron; Pokhodnya, Konstantin

    2013-03-01

    We report on the tunable dielectric properties of Mg and Nb co-doped Ba0.45Sr0.55TiO3 (BST) thin film prepared by the magnetron sputtering using BST target (pure and doped with BaMg0.33Nb0.67O3 (BMN)) on Pt/TiO2/SiO2/Al2O3 4'' wafers at 700 °C under oxygen atmosphere. The electrical measurements are conducted on 2432 metal-ferroelectric-metal capacitors using Pt as the top and bottom electrode. The crystalline structure, microstructure, and surface morphology of the films are analyzed and correlated to the films dielectric properties. The BMN doped and undoped BST films have shown tunabilities of 48% and 52%; and leakage current densities of 2.2x10-6 A/cm2 and 3.7x10-5 A/cm2, respectively at 0.5 MV/cm bias field. The results indicate that the BMN doped film exhibits a lower leakage current with no significant decrease in tunability. Due to similar electronegativity and ionic radii, it was suggested that both Mg2+ (accepter-type) and Nb5+ (donor-type) dopants substitutTi4+ ion in BST. The improvement in the film dielectric losses and leakage current with insignificant loss of tunability is attributed to the adversary effects of Mg2+ and Nb5+ in BST.

  5. On the persistence of polar domains in ultrathin ferroelectric capacitors

    Czech Academy of Sciences Publication Activity Database

    Zubko, P.; Lu, H.; Bark, C.-W.; Martí, Xavier; Santiso, J.; Eom, C.-B.; Catalan, G.; Gruverman, A.

    2017-01-01

    Roč. 29, č. 28 (2017), s. 1-8, č. článku 284001. ISSN 1361-648X R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : ultrathin barium titanate * tunnel junctions * ferroelectric domains * polarization screening * retention * negative capacitance Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

  6. Grain growth kinetics and electrical properties of lanthanum modified lead zirconate titanate (9/65/35) based ferroelectric ceramics

    International Nuclear Information System (INIS)

    Roca, R. Alvarez; Guerrero, F.; Botero, E. R.; Garcia, D.; Eiras, J. A.; Guerra, J. D. S.

    2009-01-01

    The influence of the microstructural characteristics on the dielectric and electrical properties has been investigated for Nd 3+ doped lanthanum modified lead zirconate titanate ferroelectric ceramics, obtained by the conventional solid-state reaction method, by taking into account different sintering conditions. The grain growth mechanism has been investigated and a cubic-type grain growth law was observed for samples with grain size varying from 1.00 up to 2.35 μm. The porosity and grain size dependences of the phase transition parameters, such as the maximum dielectric permittivity and its corresponding temperature (ε m and T m , respectively) were also investigated. The ac conductivity analyses followed the universal Jonscher law. The behavior of the frequency exponent (s) was analyzed through the correlated barrier hopping model. Both ac and dc conductivity results have been correlated with the observed microstructural features

  7. R-curve behaviour of ferroelectric ceramics

    International Nuclear Information System (INIS)

    Egorov, N.Ya.; Kramarov, S.O.

    2004-01-01

    The attempt's made to identify and evaluate the regularities of developing the fractures in the ferroelectric ceramics and also-study the effect of the polishing operation on the strength characteristics of the piezoceramics. The R-curve behaviour in the ferroelectric ceramics is studied on the samples of the barium titanate and lead zirconate-titanate by the four-point bending with controlled surface fractures. It is established that increasing curve of resistance to the fracture growth is observed in the piezoceramics under the conditions of the fracture stable growth. The results obtained on the polished samples prove that the mechanical processing introduces the compression surface stresses into the piezoceramic materials [ru

  8. A polarized Raman study of the relaxor and ferroelectric states of La-modified lead zirconate titanate ceramics

    International Nuclear Information System (INIS)

    El Marssi, M.; Farhi, R.; Viehland, D.

    1997-01-01

    Lanthanum modified lead zirconate titanate ceramics with La/Zr/Ti ratios of 6/40/60, 12/40/60, 5/65/35, and 9/65/35 have been studied by polarized Raman scattering. In the two former (tetragonal-type) compositions, selection rules were rather well defined and allowed an assignment of the Raman lines at lower temperature. These selection rules disappeared for 6/40/60 but remained for 12/40/60 even at higher temperatures. The behavior of the two latter (rhombohedral-type compositions) was quite different. No assignment of lines could be done. In addition, the spectra recorded in parallel and crossed polarizations were almost identical for 5/65/35 regardless of temperature. A very smeared paraelectric to ferroelectric transition was evidenced by Raman intensity measurements for this composition. On the contrary, selection rules were always present for the relaxor composition 9/65/35 which were similar to those for 12/40/60 and 6/40/60. This suggests that both tetragonal and rhombohedral-type local polar order is present for 9/65/35. The spectra of the field induced ferroelectric phase for 9/65/35 revealed no selection rules, similar to 5/65/35. This is attributed to the onset of only medium range ferroelectric order. Finally, Raman spectra recorded on powders of every composition did not reveal any selection rules, suggesting that intergranular effects might play a significant role in the behavior of these materials. copyright 1997 American Institute of Physics

  9. Effect of donor and acceptor dopants on crystallization, microstructural and dielectric behaviors of barium strontium titanate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Avadhesh Kumar, E-mail: yadav.av11@gmail.com [Department of Physics, Dr. Bheem Rao Ambedkar Government Degree College, Anaugi, Kannauj (India); Gautam, C.R. [Department of Physics, University of Lucknow, Lucknow 226007 (India); Singh, Prabhakar [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2016-07-05

    Bulk transparent barium strontium titanate borosilicate glasses in glass system (65-x)[(Ba{sub 0.6}Sr{sub 0.4}).TiO{sub 3}]-30[2SiO{sub 2}.B{sub 2}O{sub 3}]-5[K{sub 2}O]-x[A{sub 2}O{sub 3}], A = La, Fe (x = 2, 5 and 10) were prepared by rapid melt-quench technique and subsequently, converted into glass ceramics by regulated heat treatment process. The phase identification was carried out by X-ray powder diffraction and their surface morphology was studied by scanning electron microscopy. The dielectric properties were studied by impedance spectroscopic technique. Investigated glass samples were crystallized into major and secondary phases of Ba{sub 1.91}Sr{sub 0.09}TiO{sub 4} and Ba{sub 2}TiSi{sub 2}O{sub 8}, respectively. A very high dielectric constant having value upto 68000 was found in glass ceramic sample BST5K10F. This high value of dielectric constant was attributed to interfacial polarization, which arose due to conductivity difference among semiconducting crystalline phases, conducting grains and insulating grain boundaries. Donor dopant La{sub 2}O{sub 3} and acceptor dopant Fe{sub 2}O{sub 3} play an important role for enhancing crystallization, dielectric constant and retardation of dielectric loss in the samples. Moreover, higher value of dielectric constant and lower value of dielectric loss was found in Fe{sub 2}O{sub 3} doped samples in comparison to La{sub 2}O{sub 3} doped samples. - Highlights: • Bulk transparent barium strontium titanate glasses are successfully prepared. • A very high dielectric constant upto 68000 was found in glass ceramics. • La{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} play role for enhancing value of dielectric constant. • Higher dielectric constant with low dielectric loss was found in Fe{sub 2}O{sub 3} doped sample. • Such glass ceramics may be used in making capacitors for high energy storage.

  10. Ferroelectric and ferroelastic domain structures in piezoelectric ceramics

    International Nuclear Information System (INIS)

    Bursill, L.A.; Julin Peng.

    1990-01-01

    A discussion of the results of conventional and high-resolution high-voltage electron microscopic studies of two ferroelectrics, barium sodium niobate and lead zirconium titanate is presented. It is shown that a rich variety of information such as ferroelectric and/or ferroelastic domains discommensurations versus antiphase boundaries, extended versus localized chemical defects and multiphase versus grain boundaries, become accessible in both single crystal and polycrystalline piezoelectrics, when a combination of high-resolution and conventional electron optical techniques is used. 15 refs., 8 figs

  11. 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.

  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. Electron Emission And Beam Generation Using Ferroelectric Cathodes (electron Beam Generation, Lead Lanthanum Zicronate Titanate, High Power Traveling Wave Tube Amplfier)

    CERN Document Server

    Flechtner, D D

    1999-01-01

    In 1989, researchers at CERN published the discovery of significant electron emission (1– 100 A/cm2) from Lead- Lanthanum-Zirconate-Titanate (PLZT). The publication of these results led to international interest in ferroelectric cathodes studies for use in pulsed power devices. At Cornell University in 1991, experiments with Lead-Zirconate-Titanate (PZT) compositions were begun to study the feasibility of using this ferroelectric material as a cathode in the electron gun section of High Power Traveling Wave Tube Amplifier Experiments. Current-voltage characteristics were documented for diode voltages ranging from 50– 500,000 V with anode cathode gaps of.5– 6 cm. A linear current-voltage relation was found for voltages less than 50 kV. For diode voltages ≥ 200 kV, a typical Child-Langmuir V3/2 dependence was observed...

  14. The composition dependence of the photochemical reactivity of strontium barium titanate

    Science.gov (United States)

    Bhardwaj, Abhilasha

    The efficiency of particulate water photolysis catalysts is impractically low due to the recombination of intermediate species and charge carriers. The back reaction can occur easily if the oxidation and reduction sites on the surface of the catalyst are not far enough apart. It is hypothesized that it will be possible to increase the separation of the sites of the two half reactions and reduce the recombination of photogenerated charge carriers by using a ferroelectric material with permanent internal dipolar fields. This separation of the reaction sites may significantly increase the efficiency of the process. The present work compares the photochemical reactivities of ferroelectric and nonferroelectric materials (SrxBa1-xTiO 3, 0.0≤ x ≤1.0) with similar composition and structure. The reactivities are compared by measuring the color change of methylene blue dye after the aqueous dye solution reacts on the surface of ceramic sample pellets as a result of exposure to UV light. The reactivities are also compared by measuring the amount of silver that is formed when an aqueous AgNO3 solution photochemically reacts on the surface. The change in the color of the dye is measured by diffuse reflectance spectroscopy and absorbance measurements. The amount of silver is measured by atomic force microscopy. The photochemical reactivity of SrxBa1-xTiO3 shows a local maximum at the composition of the ferroelectric to non-ferroelectric transition. Also, the reactivities decrease as BaTiO3 and SrTiO3 become less pure. The dominant factors causing this trend in reactivities of SrxBa1-xTiO3 are the dielectric constant and alloy scattering. It is found that higher values of the dielectric constant increase the photochemical reactivity by enlarging the space charge region. The increase in alloy scattering in SrxBa1-xTiO 3 solid solutions as x increases from zero or decreases from 1, has adverse effect on reactivity. There are other factors such as ferroelectric polarization

  15. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    Energy Technology Data Exchange (ETDEWEB)

    Pakseresht, A.H., E-mail: amirh_pak@yahoo.com [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Rahimipour, M.R. [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Vaezi, M.R. [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Salehi, M. [Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan (Iran, Islamic Republic of)

    2016-04-15

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO{sub 3} powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

  16. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    International Nuclear Information System (INIS)

    Pakseresht, A.H.; Rahimipour, M.R.; Vaezi, M.R.; Salehi, M.

    2016-01-01

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO_3 powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

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

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, Seyyed Salman Seyyed [Imam Hossein University, Department of Materials Science and Engineering (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Islamic Azad University, Young Researchers and Elite Club, Science and Research Branch (Iran, Islamic Republic of); Atassi, Yomen [Higher Institute for Applied Sciences and Technology, Department of Applied Physics (Syrian Arab Republic)

    2016-07-15

    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.Graphical Abstract.

  18. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, Jean-Claude

    2009-01-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as alpha(Ti) = 872...

  19. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have...

  20. Titan!

    Science.gov (United States)

    Matson, Dennis L.

    2010-05-01

    Cassini-Huygens achieved Saturnian orbit on July 1, 2004. The first order of business was the safe delivery of the Huygens atmospheric probe to Titan that took place on January 14, 2005. Huygens descended under parachute obtaining observations all the way down to a safe landing. It revealed Titan for the first time. Stunning are the similarities between Titan and the Earth. Viewing the lakes and seas, the fluvial terrain, the sand dunes and other features through the hazy, nitrogen atmosphere, brings to mind the geological processes that created analogous features on the Earth. On Titan frozen water plays the geological role of rock; liquid methane takes the role of terrestrial water. The atmospheres of both Earth and Titan are predominately nitrogen gas. Titan's atmosphere contains 1.5% methane and no oxygen. The surface pressure on Titan is 1.5 times the Earth's. There are aerosol layers and clouds that come and go. Now, as Saturn proceeds along its solar orbit, the seasons are changing. The effects upon the transport of methane are starting to be seen. A large lake in the South Polar Region seems to be filling more as winter onsets. Will the size and number of the lakes in the South grow during winter? Will the northern lakes and seas diminish or dry up as northern summer progresses? How will the atmospheric circulation change? Much work remains not only for Cassini but also for future missions. Titan has many different environments to explore. These require more capable instruments and in situ probes. This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

  1. The field induced e31,f piezoelectric and Rayleigh response in barium strontium titanate thin films

    International Nuclear Information System (INIS)

    Garten, L. M.; Trolier-McKinstry, S.

    2014-01-01

    The electric field induced e 31,f piezoelectric response and tunability of Ba 0.7 Sr 0.3 TiO 3 (70:30) and Ba 0.6 Sr 0.4 TiO 3 (60:40) thin films on MgO and silicon was measured. The relative dielectric tunabilities for the 70:30 and 60:40 compositions on MgO were 83% and 70%, respectively, with a dielectric loss of less than 0.011 and 0.004 at 100 kHz. A linear increase in induced piezoelectricity to −3.0 C/m 2 and −1.5 C/m 2 at 110 kV/cm was observed in Ba 0.6 Sr 0.4 TiO 3 on MgO and Ba 0.7 Sr 0.3 TiO 3 on Si. Hysteresis in the piezoelectric and dielectric response of the 70:30 composition films was consistent with the positive irreversible dielectric Rayleigh coefficient. Both indicate a ferroelectric contribution to the piezoelectric and dielectric response over 40–80 °C above the global paraelectric transition temperature.

  2. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO{sub 3}) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Billah, Masum, E-mail: masum.buet09@gmail.com; Ahmed, A., E-mail: jhinukbuetmme@gmail.com; Rahman, Md. Miftaur, E-mail: miftaurrahman@mme.buet.ac.bd [Department of Materials & Metallurgical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Mahbub, Rubbayat, E-mail: rubayyatm@gce.buet.ac.bd [Department of Glass and Ceramic Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Gafur, M. A., E-mail: d-r-magafur@bcsir.gov.bd [Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh); Bashar, M. Shahriar, E-mail: bashar@agni.com [Institute of Fuel Research & Development, Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh)

    2016-07-12

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La{sub 2}O{sub 3}) doped Barium Titanate (BaTiO{sub 3}) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO{sub 3} with 0.3, 0.5 and 0.7 mole% La{sub 2}O{sub 3} under different sintering parameters. The raw materials used were La{sub 2}O{sub 3} nano powder of ~80 nm grain size and 99.995% purity and BaTiO{sub 3} nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO{sub 3} ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La{sub 2}O{sub 3}) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La{sub 2}O{sub 3} with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La{sup 3+} concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO{sub 3} ceramics.

  3. DFT study of the polarization behaviors of various distorted barium titanate crystals: The role of atomic displacements

    Science.gov (United States)

    Mirseraji, Mojtaba; Shahraki, Mehran Gholipour

    2018-06-01

    A Local Density Approximation (LDA) was employed to investigate the influence of applied strains on valence charge distributions, atomic displacements, Tisbnd O (3) bond distances and the total polarizations in barium titanate (BaTiO3). Four types of various strains were imposed on perfect tetragonal BaTiO3 along the a, c, ab and abc axial directions. Electromechanical properties of BaTiO3 were evaluated in LDA framework and a good agreement with previous results was achieved. The results show that, in the cases of a, ab strains, the values of polarization are almost constant in negative strains and increased by gradual increasing of the positive strains after a sudden enhancement at about +0.1% strain. In the case of c-strain, axial oxygen and Ti atoms underwent the highest displacements and the polarization linearly increased by applied strain. The case of abc-strain, represent the both types of features. In negative abc-strain show a similar polarization behavior like c-strain case and in positive region, polarization behavior is the same as a- and ab-strain cases. In the abc-strains of -0.3% and +0.1%, an abrupt jump in total polarization curve and a small change, are observed due to abnormal atomic displacements. In the most cases a direct relation between polarization and Tisbnd O (3) bond distance was also beheld. Finally, the effects of valence charge distributions on the atomic displacements and total polarizations are studied. It is found that there is a direct relation between polarization and Valence Charge Asymmetry of 3d -orbitals.

  4. Effects of Thickness, Pulse Duration, and Size of Strip Electrode on Ferroelectric Electron Emission of Lead Zirconate Titanate Films

    Science.gov (United States)

    Yaseen, Muhammad; Ren, Wei; Chen, Xiaofeng; Feng, Yujun; Shi, Peng; Wu, Xiaoqing

    2018-02-01

    Sol-gel-derived lead zirconate titanate (PZT) thin-film emitters with thickness up to 9.8 μm have been prepared on Pt/TiO2/SiO2/Si wafer via chemical solution deposition with/without polyvinylpyrrolidone (PVP) modification, and the relationship between the film thickness and electron emission investigated. Notable electron emission was observed on application of a trigger voltage of 120 V for PZT film with thickness of 1.1 μm. Increasing the film thickness decreased the threshold field to initiate electron emission for non-PVP-modified films. In contrast, the electron emission behavior of PVP-modified films did not show significant dependence on film thickness, probably due to their porous structure. The emission current increased with decreasing strip width and space between strips. Furthermore, it was observed that increasing the duration of the applied pulse increased the magnitude of the emission current. The stray field on the PZT film thickness was also calculated and found to increase with increasing ferroelectric sample thickness. The PZT emitters were found to be fatigue free up to 105 emission cycles. Saturated emission current of around 25 mA to 30 mA was achieved for the electrode pattern used in this work.

  5. Tunable double-channel filter based on two-dimensional ferroelectric photonic crystals

    International Nuclear Information System (INIS)

    Jiang, Ping; Ding, Chengyuan; Hu, Xiaoyong; Gong, Qihuang

    2007-01-01

    A tunable double-channel filter is presented, which is based on a two-dimensional nonlinear ferroelectric photonic crystal made of cerium doped barium titanate. The filtering properties of the photonic crystal filter can be tuned by adjusting the defect structure or by a pump light. The influences of the structure disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed

  6. Tunable double-channel filter based on two-dimensional ferroelectric photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ping [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Ding, Chengyuan [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Hu, Xiaoyong [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)]. E-mail: xiaoyonghu@pku.edu.cn; Gong, Qihuang [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)]. E-mail: qhgong@pku.edu.cn

    2007-04-02

    A tunable double-channel filter is presented, which is based on a two-dimensional nonlinear ferroelectric photonic crystal made of cerium doped barium titanate. The filtering properties of the photonic crystal filter can be tuned by adjusting the defect structure or by a pump light. The influences of the structure disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed.

  7. Image plane digital holographic microscope for the inspection of ferroelectric single crystals.

    Czech Academy of Sciences Publication Activity Database

    Psota, Pavel; Mokrý, Pavel; Lédl, Vít; Vojtíšek, Petr

    2016-01-01

    Roč. 55, č. 12 (2016), č. článku 121731. ISSN 0091-3286 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : Digital holography * barium titanate * domain pattern * ferroelectric crystals * holographic microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.082, year: 2016 http://dx.doi.org/10.1117/1.OE.55.12.121731

  8. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, J.-C.; Kesler, V.G.; Troitskaia, I.B.

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr 2 Ti 2 O 7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr 2 Ti 2 O 7 have been determined as α Ti =872.8 and α O =1042.3 eV. Variations of cation–anion bond ionicity have been discussed using binding energy differences Δ Ti =(BE O 1s–BE Ti 2p 3/2 )=71.6 eV and Δ Pr =BE(Pr 3d 5/2 )−BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: ► Solid state synthesis of polar titanate Pr 2 Ti 2 O 7 . ► Structural and spectroscopic properties and electronic structure determination. ► Ti–O and Pr–O bonding analysis using Ti 2p 3/2 , Pr 3d 5/2 and O 1s core levels.

  9. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

    2009-02-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as αTi = 872.4 and αO = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences ΔTi = (BE O 1s - BE Ti 2p3/2) = 71.6 eV and ΔLa = (BE La 3d5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  10. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V V; Gavrilova, T A; Grivel, J-C; Kesler, V G

    2009-01-01

    The electronic structure of binary titanate La 2 Ti 2 O 7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La 2 Ti 2 O 7 are determined as α Ti = 872.4 and α O = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences Δ Ti = (BE O 1s - BE Ti 2p 3/2 ) = 71.6 eV and Δ La = (BE La 3d 5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  11. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.; Troitskaia, I. B.

    2012-11-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr2Ti2O7 have been determined as αTi=872.8 and αO=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences ΔTi=(BE O 1s-BE Ti 2p3/2)=71.6 eV and ΔPr=BE(Pr 3d5/2)-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides.

  12. 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

  13. Processing/structure/property Relationships of Barium Strontium Titanate Thin Films for Dynamic Random Access Memory Application.

    Science.gov (United States)

    Peng, Cheng-Jien

    The purpose of this study is to see the application feasibility of barium strontium titanate (BST) thin films on ultra large scale integration (ULSI) dynamic random access memory (DRAM) capacitors through the understanding of the relationships among processing, structure and electrical properties. Thin films of BST were deposited by multi-ion -beam reactive sputtering (MIBERS) technique and metallo -organic decomposition (MOD) method. The processing parameters such as Ba/Sr ratio, substrate temperature, annealing temperature and time, film thickness and doping concentration were correlated with the structure and electric properties of the films. Some effects of secondary low-energy oxygen ion bombardment were also examined. Microstructures of BST thin films could be classified into two types: (a) Type I structures, with multi-grains through the film thickness, for amorphous as-grown films after high temperature annealing, and (b) columnar structure (Type II) which remained even after high temperature annealing, for well-crystallized films deposited at high substrate temperatures. Type I films showed Curie-von Schweidler response, while Type II films showed Debted type behavior. Type I behavior may be attributed to the presence of a high density of disordered grain boundaries. Two types of current -voltage characteristics could be seen in non-bombarded films depending on the chemistry of the films (doped or undoped) and substrate temperature during deposition. Only the MIBERS films doped with high donor concentration and deposited at high substrate temperature showed space-charge -limited conduction (SCLC) with discrete shallow traps embedded in trap-distributed background at high electric field. All other non-bombarded films, including MOD films, showed trap-distributed SCLC behavior with a slope of {~}7.5-10 due to the presence of grain boundaries through film thickness or traps induced by unavoidable acceptor impurities in the films. Donor-doping could

  14. Microstructure and thermal properties of dysprosium and thulium co-doped barium titanate ceramics for high performance multilayer ceramic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinseong; Kim, Dowan; Noh, Taimin [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Ahn, Byungmin [Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States); Lee, Heesoo, E-mail: heesoo@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2011-09-15

    Highlights: > Dy/Tm co-doping method in BaTiO{sub 3} was suggested to improve electrical properties and temperature stability simultaneously. > We examined these properties in terms of microstructural analysis and substitution rate. > Increase of Dy{sub 2}O{sub 3} addition enhanced dielectric constant. > Increase of Tm{sub 2}O{sub 3} addition enhanced temperature stability. > Improved electrical properties and temperature stability through Dy/Tm co-doping were deduced from formation of electrons and core-shell structure. - Abstract: The co-doping characteristics on microstructure and thermal properties of barium titanate (BaTiO{sub 3}) were investigated to elucidate formation of core-shell structure by dysprosium (Dy) and thulium (Tm) addition in the BaTiO{sub 3}-Dy{sub 2}O{sub 3}-Tm{sub 2}O{sub 3} system. The dielectrics co-doped with 0.7 mol% Dy{sub 2}O{sub 3} and 0.3 mol% Tm{sub 2}O{sub 3} had the dielectric constant up to 2200 as a function of temperature, which was 30% higher than that of specimen containing only Tm{sub 2}O{sub 3} at the room temperature. It could be explained by the fact that the increase of Dy{sub 2}O{sub 3} addition contributed to the improvement of dielectric constant. On the other hand, the rapid diffusion rate of Dy{sup 3+} ions in BaTiO{sub 3} showed an adverse effect on temperature stability caused by destruction of core-shell. As the compensation for shell expansion in BaTiO{sub 3}, the reinforcement of the core-shell structure through the addition of Tm{sub 2}O{sub 3} was confirmed by TEM-EDS analysis and attributed the temperature coefficient of capacitance (TCC) in a reliability condition (-55 deg. C to 125 deg. C, {Delta}C = {+-}15% or less). The enhanced electrical properties and temperature stability could be deduced from the generation of electrons and the formation core-shell structure in co-doped BaTiO{sub 3} system respectively.

  15. Pressure dependence of electron density distribution and d-p-π hybridization in titanate perovskite ferroelectrics

    Science.gov (United States)

    Yamanaka, Takamitsu; Nakamoto, Yuki; Ahart, Muhtar; Mao, Ho-kwang

    2018-04-01

    Electron density distributions of PbTi O3 , BaTi O3 , and SrTi O3 were determined by synchrotron x-ray powder diffraction up to 55 GPa at 300 K and ab initio quantum chemical molecular orbital (MO) calculations, together with a combination of maximum entropy method calculations. The intensity profiles of Bragg peaks reveal split atoms in both ferroelectric PbTi O3 and BaTi O3 , reflecting the two possible positions occupied by the Ti atom. The experimentally obtained atomic structure factor was used for the determination of the deformation in electron density and the d-p-π hybridization between dx z (and dy z) of Ti and px (and py) of O in the Ti-O bond. Ab initio MO calculations proved the change of the molecular orbital coupling and of Mulliken charges with a structure transformation. The Mulliken charge of Ti in the Ti O6 octahedron increased in the ionicity with increasing pressure in the cubic phase. The bonding nature is changed with a decrease in the hybridization of the Ti-O bond and the localization of the electron density with increasing pressure. The hybridization decreases with pressure and disappears in the cubic paraelectric phase, which has a much more localized electron density distribution.

  16. Ferroelectric behavior of a lead titanate nanosphere due to depolarization fields and mechanical stresses

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Landeta, J.; Lascano, I.

    2017-07-01

    A theorical model has been developed based on the theory of Ginzburg-Landau-Devonshire to study and predict the effects the decreasing of size particle in a nanosphere of PbTiO3 subjected to the action of depolarization fields and mechanical stress. It was considered that the nanosphere is surrounded by a layer of space charges on its surface, and containing 180° domains generated by minimizing free energy of depolarization. Energy density of depolarization, wall domain and electro-elastic energy have been incorporated into the free energy of the theory Ginzburg-Landau-Devonshire. Free energy minimization was performed to determine the spontaneous polarization and transition temperature system. These results show that the transition temperature for nanosphere is substantially smaller than the corresponding bulk material. Also, it has been obtained that the stability of the ferroelectric phase of nanosphere is favored for configurations with a large number of 180° domains, with the decreasing of thickness space charge layer, and the application of tensile stress and decreases with compressive stress. (Author)

  17. Chemical solution deposited BaPbO3 buffer layers for lead zirconate titanate ferroelectric films

    International Nuclear Information System (INIS)

    Tseng, T.-K.; Wu, J.-M.

    2005-01-01

    Conductive perovskite BaPbO 3 (BPO) films have been prepared successfully by chemical solution deposition method through spin-coating on Pt/Ti/SiO 2 /Si substrates. The choice of baking temperature is a key factor on the development of conducting BPO perovskite phase. When the baking temperature is higher than 350 deg. C, the BPO films contain a high content of BaCO 3 phase after annealing at temperatures higher than 500 deg. C. If the baking temperature is chosen lower than 300 deg. C, such as 200 deg. C, the annealed BPO films consist mostly of perovskite with only traces of BaCO 3 . Choosing 200 deg. C as the baking temperature, the BPO films developed single perovskite phase at temperatures as low as 550 deg. C. The perovskite BPO phase is stable in the range of 550-650 deg. C and the measured sheet resistance of the BPO films is about 2-3 Ω/square. The perovskite BPO film as a buffer layer provides improvement in electric properties of lead zirconate titanate films

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

    International Nuclear Information System (INIS)

    Ulloa, Maritza Eliza Perez

    2007-01-01

    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 sample

  19. Incipient ferroelectric to a possible ferroelectric transition in Te4+ doped calcium copper titanate (CaCu3Ti4O12 ceramics at low temperature as evidenced by Raman and dielectric spectroscopy

    Directory of Open Access Journals (Sweden)

    Nabadyuti Barman

    2017-03-01

    Full Text Available Partial replacement of Ti4+ by Te4+ ions in calcium copper titanate lattice improved its dielectric behaviour mostly due to cubic-to-tetragonal structural transformation and associated distortion in TiO6 octahedra. The relative permittivity values (23–30 x 103 of Te4+ doped ceramics is more than thrice that of un-doped ceramics (8 x 103 at 1 kHz. A decreasing trend in relative permittivity with increasing temperature (50–300 K is observed for all the samples. Barrett’s formula, as a signature of incipient ferroelectricity, is invoked to rationalize the relative permittivity variation as a function of temperature. A systematic investigation supported by temperature dependent Raman studies reveal a possible ferroelectric transition in Te4+ doped ceramic samples below 120 K. The possible ferroelectric transition is attributed to the interactions between quasi-local vibrations associated with the micro-clusters comprising TiO6 and TeO6 structural units and indirect dipole-dipole interactions of off-center B–cations (Ti4+ and Te4+ in double perovskite lattice.

  20. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    Wintec

    nese doped BaTiO3 ceramics, sintered at 1400°C in air, changes from tetragonal to hexagonal between 0⋅5 and. 1⋅7 mole% of manganese (Langhammer et al 2000). As a driving force of the transformation from the cubic to the hexagonal crystal structure, the influence of the Jahn–. Teller distortion is proposed. The grain ...

  1. Studies on the effects of titanate and silane coupling agents on the performance of poly (methyl methacrylate)/barium titanate denture base nanocomposites.

    Science.gov (United States)

    Elshereksi, Nidal W; Ghazali, Mariyam J; Muchtar, Andanastuti; Azhari, Che H

    2017-01-01

    This study aimed to fabricate and characterise silanated and titanated nanobarium titanate (NBT) filled poly(methyl methacrylate) (PMMA) denture base composites and to evaluate the behaviour of a titanate coupling agent (TCA) as an alternative coupling agent to silane. The effect of filler surface modification on fracture toughness was also studied. Silanated, titanated and pure NBT at 5% were incorporated in PMMA matrix. Neat PMMA matrix served as a control. NBT was sonicated in MMA prior to mixing with the PMMA. Curing was carried out using a water bath at 75°C for 1.5h and then at 100°C for 30min. NBT was characterised via Fourier transform-infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis before and after surface modification. The porosity and fracture toughness of the PMMA nanocomposites (n=6, for each formulation and test) were also evaluated. NBT was successfully functionalised by the coupling agents. The TCA exhibited the lowest percentage of porosity (0.09%), whereas silane revealed 0.53% porosity. Statistically significant differences in fracture toughness were observed among the fracture toughness values of the tested samples (pPMMA composites. Thus, TCA seemed to be more effective than silane. Minimising the porosity level could have the potential to reduce fungus growth on denture base resin to be hygienically accepTable Such enhancements obtained with Ti-NBT could lead to promotion of the composites' longevity. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  3. 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.

  4. Computer simulations of sequency-dependent dielectric response of 90-degree domain walls in tetragonal barium titanate

    Czech Academy of Sciences Publication Activity Database

    Márton, Pavel; Hlinka, Jiří

    2008-01-01

    Roč. 373, č. 1 (2008), s. 139-144 ISSN 0015-0193 R&D Projects: GA ČR GA202/06/0411 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric and ferroelastic domains * BaTiO 3 * Ginzburg-Landau theory * mobility Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.562, year: 2008

  5. 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.

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

    International Nuclear Information System (INIS)

    Pahuja, Poonam; Kotnala, R.K.; Tandon, R.P.

    2014-01-01

    Highlights: • Rare earth ions Dy 3+ , Gd 3+ and Sm 3+ have been substituted in Ba 0.95 Sr 0.05 TiO 3 (BST). • Ni 0.8 Co 0.2 Fe 2 O 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 3+ , Gd 3+ and Sm 3+ ) on various properties of Ba 0.95 Sr 0.05 TiO 3 (BST) i.e. the composition Ba 0.95−1.5x Sr 0.05 R x TiO 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 0.8 Co 0.2 Fe 2 O 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 2+ and Ti 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

  7. Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition

    Directory of Open Access Journals (Sweden)

    Junsheng Liang

    2016-01-01

    Full Text Available Dense and crack-free barium titanate (BaTiO3, BTO thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film.

  8. 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)

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

    International Nuclear Information System (INIS)

    Wang, H.-W.; Nien, S.-W.; Lee, K.-C.; Wu, M.-C.

    2005-01-01

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

  10. Damage-free patterning of ferroelectric lead zirconate titanate thin films for microelectromechanical systems via contact printing

    Science.gov (United States)

    Welsh, Aaron

    This thesis describes the utilization and optimization of the soft lithographic technique, microcontact printing, to additively pattern ferroelectric lead zirconate titanate (PZT) thin films for application in microelectromechanical systems (MEMS). For this purpose, the solution wetting, pattern transfer, printing dynamics, stamp/substrate configurations, and processing damages were optimized for incorporation of PZT thin films into a bio-mass sensor application. This patterning technique transfers liquid ceramic precursors onto a device stack in a desired configuration either through pattern definition in the stamp, substrate or both surfaces. It was determined that for ideal transfer of the pattern from the stamp to the substrate surface, wetting between the solution and the printing surface is paramount. To this end, polyurethane-based stamp surfaces were shown to be wet uniformly by polar solutions. Patterned stamp surfaces revealed that printing from raised features onto flat substrates could be accomplished with a minimum feature size of 5 mum. Films patterned by printing as a function of thickness (0.1 to 1 mum) showed analogous functional properties to continuous films that were not patterned. Specifically, 1 mum thick PZT printed features had a relative permittivity of 1050 +/- 10 and a loss tangent of 2.0 +/- 0.4 % at 10 kHz; remanent polarization was 30 +/- 0.4 muC/cm 2 and the coercive field was 45 +/- 1 kV/cm; and a piezoelectric coefficient e31,f of -7 +/- 0.4 C/m2. No pinching in the minor hysteresis loops or splitting of the first order reversal curve (FORC) distributions was observed. Non-uniform distribution of the solution over the printed area becomes more problematic as feature size is decreased. This resulted in solutions printed from 5 mum wide raised features exhibiting a parabolic shape with sidewall angles of ˜ 1 degree. As an alternative, printing solutions from recesses in the stamp surface resulted in more uniform solution thickness

  11. The influence of the coexistence of ferroelectric and antiferroelectric states on the lead lanthanum zirconate titanate crystal structure

    International Nuclear Information System (INIS)

    Ishchuk, V M; Baumer, V N; Sobolev, V L

    2005-01-01

    We present results of detailed investigation of the crystal structure of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 solid solutions. In this letter our attention is concentrated on the series of solid solutions with x = 6% usually referred to as relaxor ferroelectrics. We have established the reasons for the non-cubic crystal structure of these solid solutions at the temperatures below T C . It is demonstrated that the peculiarities of the properties of Pb 1-3x/2 La x (Zr 1-y Ti y )O 3 depend on the position of a particular solid solution with respect to the hysteresis ferroelectric-antiferroelectric region in the 'Ti-content-temperature' phase diagram. (letter to the editor)

  12. Study of influence of fuel on dielectric and ferroelectric properties of bismuth titanate ceramics synthesized using solution based combustion technique

    International Nuclear Information System (INIS)

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

    2015-01-01

    The effect of fuel characteristics on the processing and properties of bismuth titanate (BIT) ceramics obtained by solution combustion route using different fuels are reported in this paper. Dextrose, urea and glycine were used as fuel in this study. The obtained bismuth titanate ceramics were characterized by using XRD, SEM at different stages of sample preparation. It was observed that BIT obtained by using dextrose as fuel shows higher dielectric constant and higher remnant polarization due to smaller grain size and lesser c-axis growth as compared to the samples with urea and glycine as fuel. The electrical behavior of the samples with respect to temperature and frequency was also investigated to understand relaxation phenomenon. (paper)

  13. Electro-optic tunable multi-channel filter in two-dimensional ferroelectric photonic crystals

    International Nuclear Information System (INIS)

    Fu, Yulan; Zhang, Jiaxiang; Hu, Xiaoyong; Gong, Qihuang

    2010-01-01

    An electro-optic tunable multi-channel filter is presented, which is based on a two-dimensional ferroelectric photonic crystal made of barium titanate. The filtering properties of the photonic crystal filter can be tuned by an applied voltage or by adjusting the structural parameters. The channel shifts about 30 nm under excitation of an applied voltage of 54.8 V. The influences of the structural disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed

  14. Down-conversion luminescence and its temperature-sensing properties from Er3+-doped sodium bismuth titanate ferroelectric thin films

    Science.gov (United States)

    Wang, Shanshan; Zheng, Shanshan; Zhou, Hong; Pan, Anlian; Wu, Guangheng; Liu, Jun-ming

    2015-11-01

    Here, we demonstrate outstanding temperature-sensing properties from Na0.5Bi0.49Er0.01TiO3 (NBT:Er) thin films. The perovskite phase for them is stable in the temperature range from 80 to 440 K. Interestingly, the Er doping enhances the ferroelectric polarization and introduces local dipolar, which are positive for temperature sensing. Pumped by a 488-nm laser, the NBT:Er thin films show strong green luminescence with two bands around 525 and 548 nm. The intensity ratio I 525/ I 548 can be used for temperature sensing, and the maximum sensitivity is about 2.3 × 10-3 K-1, higher than that from Er-doped silicon oxide. These suggest NBT:Er thin film is a promising candidate for temperature sensor.

  15. Fracture mechanisms in ferroelectric-ferroelastic lead zirconate titanate (Zr:Ti = 0.54:0.46) ceramics

    International Nuclear Information System (INIS)

    Mehta, K.; Virkar, A.V.

    1990-01-01

    Fracture toughness, K IC , of a single-phase commercial lead zirconate titanate (PZT) ceramic of tetragonal structure was measured using the single edge notched beam method above and below the Curie temperature. Domain switching (poling) under electrical and mechanical loading was examined using x-ray diffraction. Surface grinding, electrical poling, and mechanical poling caused crystallographic texture. Similar texture, indicative of domain switching, was also observed on fracture surfaces of some samples fractured at room temperature. At room temperature, the highest K IC measured was 1.85 MPa · m 1/2 , while above the Curie temperature it was about 1.0 MPa · m 1/2 . Cracks emanating from Vickers indents in poled samples were different in the poling and the transverse directions. The difference in crack sizes is explained on the basis of domain switching during crack growth. These results indicate that ferroelastic domain switching (twinning) is a viable toughening mechanism in the PZT materials tested

  16. Tunable Microwave Filter Design Using Thin-Film Ferroelectric Varactors

    Science.gov (United States)

    Haridasan, Vrinda

    rejection, and constant bandwidth is designed, simulated, fabricated and measured. The filters are fabricated using barium strontium titanate (BST) varactors. Electromagnetic simulations and measured results of the tunable two-pole ferroelectric filter are analyzed to explore the origins of high insertion loss in ferroelectric filters. The results indicate that the high-permittivity of the BST (a ferroelectric) not only makes the filters tunable and compact, but also increases the conductive loss of the ferroelectric-based tunable resonators which translates into high insertion loss in ferroelectric filters.

  17. Thickness dependent charge transport in ferroelectric BaTiO3 heterojunctions

    Science.gov (United States)

    Singh, Pooja; Rout, P. K.; Singh, Manju; Rakshit, R. K.; Dogra, Anjana

    2015-09-01

    We have investigated the effect of ferroelectric barium titanate (BaTiO3) film thickness on the charge transport mechanism in pulsed laser deposited epitaxial metal-ferroelectric semiconductor junctions. The current (I)-voltage (V) measurements across the junctions comprising of 20-500 nm thick BaTiO3 and conducting bottom electrode (Nb: SrTiO3 substrate or La2/3Ca1/3MnO3 buffer layer) demonstrate the space charge limited conduction. Further analysis indicates a reduction in the ratio of free to trapped carriers with increasing thickness in spite of decreasing trap density. Such behaviour arises the deepening of the shallow trap levels (I-V curves implies a bipolar resistive switching behaviour, which can be explained in terms of charge trapping and de-trapping process.

  18. Uncooled monolithic ferroelectric IRFPA technology

    Science.gov (United States)

    Belcher, James F.; Hanson, Charles M.; Beratan, Howard R.; Udayakumar, K. R.; Soch, Kevin L.

    1998-10-01

    Once relegated to expensive military platforms, occasionally to civilian platforms, and envisioned for individual soldiers, uncooled thermal imaging affords cost-effective solutions for police cars, commercial surveillance, driving aids, and a variety of other industrial and consumer applications. System prices are continuing to drop, and swelling production volume will soon drive prices substantially lower. The impetus for further development is to improve performance. Hybrid barium strontium titanate (BST) detectors currently in production are relatively inexpensive, but have limited potential for improved performance. The MTF at high frequencies is limited by thermal conduction through the optical coating. Microbolometer arrays in development at Raytheon have recently demonstrated performance superior to hybrid detectors. However, microbolometer technology lacks a mature, low-cost system technology and an abundance of upgradable, deployable system implementations. Thin-film ferroelectric (TFFE) detectors have all the performance potential of microbolometers. They are also compatible with numerous fielded and planned system implementations. Like the resistive microbolometer, the TFFE detector is monolithic; i.e., the detector material is deposited directly on the readout IC rather than being bump bonded to it. Imaging arrays of 240 X 320 pixels have been produced, demonstrating the feasibility of the technology.

  19. Barium enema

    Science.gov (United States)

    ... series; Colorectal cancer - lower GI series; Colorectal cancer - barium enema; Crohn disease - lower GI series; Crohn disease - barium enema; Intestinal blockage - lower GI series; Intestinal blockage - ...

  20. 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.

  1. Effect of substrate temperature in the structural, optical and ferroelectric properties of thin films of BaTiO{sub 3} deposited by RF sputtering; Efecto de la temperatura de substrato en las propiedades estructurales, opticas y ferroelectricas de peliculas delgadas de BaTiO{sub 3} depositadas por RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Marquez H, A. [Universidad Autonoma de San Luis Potosi, Coordinacion Academica Region Altiplano, Carretera a Cedral Km. 5 -600, Matehuala, 78800 San Luis Potosi (Mexico); Hernandez R, E.; Zapata T, M. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Calz. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Calzadilla A, O. [Universidad de la Habana, Facultad de Fisica-IMRE, San Lazaro y L. Municipio Plaza de la Revolucion, La Habana (Cuba); Melendez L, M. [IPN, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Apdo. Postal 14-740, 07000 Mexico D. F. (Mexico)

    2012-07-01

    Thin films of Barium Titanate (BaTiO{sub 3}) were grown on nichrome and quartz substrates, using a BaTiO{sub 3} target, by RF sputtering technique. We varied the substrate temperature in order to study its effect on the structural, optical and ferroelectric properties of the samples. The results of the X-ray diffraction showed tetragonal structure with increases of the crystallinity as increases the substrate temperature. Furthermore, it observed by ultraviolet-visible spectroscopy that the band gap decreased as the substrate temperature increases showing abrupt sharp decrease at 494.8{sup o} C. The ferroelectric properties of the films showed a dependence with substrate temperature, the best ferroelectric answer was obtained at 494.8{sup o} C. (Author)

  2. Photovoltaic effect in ferroelectric ceramics

    Science.gov (United States)

    Epstein, D. J.; Linz, A.; Jenssen, H. P.

    1982-01-01

    The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv).

  3. Predicting the effective response of bulk polycrystalline ferroelectric ceramics via improved spectral phase field methods

    Science.gov (United States)

    Vidyasagar, A.; Tan, W. L.; Kochmann, D. M.

    2017-09-01

    Understanding the electromechanical response of bulk polycrystalline ferroelectric ceramics requires scale-bridging approaches. Recent advances in fast numerical methods to compute the homogenized mechanical response of materials with heterogeneous microstructure have enabled the solution of hitherto intractable systems. In particular, the use of a Fourier-based spectral method as opposed to the traditional finite element method has gained significant interest in the homogenization of periodic microstructures. Here, we solve the periodic, electro-mechanically-coupled boundary value problem at the mesoscale of polycrystalline ferroelectrics in order to extract the effective response of barium titanate (BaTiO3) and lead zirconate titanate (PZT) under applied electric fields. Results include the effective electric hysteresis and the associated butterfly curve of strain vs. electric field for mean stress-free electric loading. Computational predictions of the 3D polycrystalline response show convincing agreement with our experimental electric cycling and strain hysteresis data for PZT-5A. In addition to microstructure-dependent effective physics, we also show how finite-difference-based approximations in the spectral solution scheme significantly reduce instability and ringing phenomena associated with spectral techniques and lead to spatial convergence with h-refinement, which have been major challenges when modeling high-contrast systems such as polycrystals.

  4. Structural and electrical properties of Barium Titanate (BaTiO3 and Neodymium doped BaTiO3 (Ba0.995Nd0.005TiO3

    Directory of Open Access Journals (Sweden)

    Tuan Sulong Tuan Amirah

    2017-01-01

    Full Text Available Barium titanate (BaTiO3 and Neodymium (Nd doped BaTiO3 with composition Ba0.995Nd0.005TiO3 were prepared using conventional solid state reaction method to study the dielectric properties of materials. Pure phase samples were found at final heating temperature of 1400°C for overnight. X-ray diffraction analysis reveals the changes in the lattice parameter and unit cell volume of the pure perovskite tetragonal structure with space group (P4mm. Electrical analysis is carried out to investigate the dielectric properties, conductivity behaviour and dielectric loss of BaTiO3 and Ba0.995Nd0.005TiO3. Ba0.995Nd0.005TiO3 have a broaden dielectric peaks with high permittivity of 8000 and reasonably low loss tan δ which is about 0.004 (1 kHz.

  5. High-k 3D-barium titanate foam/phenolphthalein poly(ether sulfone)/cyanate ester composites with frequency-stable dielectric properties and extremely low dielectric loss under reduced concentration of ceramics

    Science.gov (United States)

    Zheng, Longhui; Yuan, Li; Guan, Qingbao; Liang, Guozheng; Gu, Aijuan

    2018-01-01

    Higher dielectric constant, lower dielectric loss and better frequency stability have been the developing trends for high dielectric constant (high-k) materials. Herein, new composites have been developed through building unique structure by using hyperbranched polysiloxane modified 3D-barium titanate foam (BTF) (BTF@HSi) as the functional fillers and phenolphthalein poly(ether sulfone) (cPES)/cyanate ester (CE) blend as the resin matrix. For BTF@HSi/cPES/CE composite with 34.1 vol% BTF, its dielectric constant at 100 Hz is as high as 162 and dielectric loss is only 0.007; moreover, the dielectric properties of BTF@HSi/cPES/CE composites exhibit excellent frequency stability. To reveal the mechanism behind these attractive performances of BTF@HSi/cPES/CE composites, three kinds of composites (BTF/CE, BTF/cPES/CE, BTF@HSi/CE) were prepared, their structure and integrated performances were intensively investigated and compared with those of BTF@HSi/cPES/CE composites. Results show that the surface modification of BTF is good for preparing composites with improved thermal stability; while introducing flexible cPES to CE is beneficial to fabricate composites with good quality through effectively blocking cracks caused by the stress concentration, and then endowing the composites with good dielectric properties at reduced concentration of ceramics.

  6. High-frequency, transient magnetic susceptibility of ferroelectrics

    Science.gov (United States)

    Grimes, Craig A.

    1996-10-01

    A significant high-frequency magnetic susceptibility was measured both in weakly polarized and nonpolarized samples of barium titanate, lead zirconate titanate, and carnauba wax. Magnetic susceptibility measurements were made from 10 to 500 MHz using a thin film permeameter at room temperature; initial susceptibilities ranged from 0.1 to 2.5. These values are larger than expected for paramagnets and smaller than expected for ferromagnets. It was found that the magnetic susceptibility decreases rapidly with exposure to the exciting field. The origin of the magnetic susceptibility is thought to originate with the applied time varying electric field associated with the susceptibility measurements. An electric field acts to rotate an electric dipole, creating a magnetic quadrupole if the two moments are balanced, and a net magnetic dipole moment if imbalanced. It is thought that local electrostatic fields created at ferroelectric domain discontinuities associated with grain boundaries create an imbalance in the anion rotation that results in a net, measurable, magnetic moment. The origin of the magnetic aftereffect may be due to the local heating of the material through the moving charges associated with the magnetic moment.

  7. Correlation of electron backscatter diffraction and piezoresponse force microscopy for the nanoscale characterization of ferroelectric domains in polycrystalline lead zirconate titanate

    Science.gov (United States)

    Burnett, T. L.; Weaver, P. M.; Blackburn, J. F.; Stewart, M.; Cain, M. G.

    2010-08-01

    The functional properties of ferroelectric ceramic bulk or thin film materials are strongly influenced by their nanostructure, crystallographic orientation, and structural geometry. In this paper, we show how, by combining textural analysis, through electron backscattered diffraction, with piezoresponse force microscopy, quantitative measurements of the piezoelectric properties can be made at a scale of 25 nm, smaller than the domain size. The combined technique is used to obtain data on the domain-resolved effective single crystal piezoelectric response of individual crystallites in Pb(Zr0.4Ti0.6)O3 ceramics. The results offer insight into the science of domain engineering and provide a tool for the future development of new nanostructured ferroelectric materials for memory, nanoactuators, and sensors based on magnetoelectric multiferroics.

  8. A Reconfigurable Coplanar Waveguide Bowtie Antenna Using an Integrated Ferroelectric Thin-Film Varactor

    Directory of Open Access Journals (Sweden)

    K. C. Pan

    2012-01-01

    Full Text Available A novel printed antenna with a frequency reconfigurable feed network is presented. The antenna consists of a bowtie structure patch radiating element in the inner space of an annulus that is on a nongrounded substrate with a ferroelectric (FE Barium Strontium Titanate (BST thin film. The bowtie patch is fed by a coplanar waveguide (CPW transmission line that also includes a CPW-based BST shunt varactor. Reconfiguration of the compact 8 mm × 8 mm system has been demonstrated by shifting the antenna system’s operating frequency 500 MHz in the 7–9 GHz band by applying a DC voltage bias.

  9. Development and construction of a novel MOCVD facility for the growth of ferroelectric thin layers

    International Nuclear Information System (INIS)

    Schaefer, P.R.

    2002-02-01

    This thesis deals with the production of ferroelectric thin films using the MOCVD technology. The main focus is put on the design and construction of a complete MOCVD research system that is equipped with a novel non-contact vaporizer system. The precursors are nebulized in an ultrasonic atomizer and injected into a hot gas stream, so they can vaporize without getting into contact with a hot surface. Hence, one of the biggest disadvantages of conventional vaporizer concepts, the contamination of the vaporizing element with decomposing chemicals, could be avoided completely, resulting in a nearly maintenance-free system. In a direct comparison with the well-established Direct Liquid Injection Subsystem DLI-25C from MKS Instruments, the advantages of non-contact evaporation were clearly demonstrated. Additionally, the scope of this work included the development of standard deposition processes for the ternary oxides SrTiO 3 , BaTiO 3 und PbTiO 3 and growth studies were performed. Electrical measurements performed on MIM structures with Pt electrodes and SrTiO 3 as dielectric indicate a high film quality comparable with results presented in the literature. Furthermore, for the first time the solid solution (Pb x Ba 1-x )TiO 3 has been deposited by MOCVD. This material system is widely unknown in thin film form and it is well suited as a model system to investigate the influence of mechanical stresses on the film properties, because it represents a transition between the (as a thin film) superparaelectric barium titanate and the ferroelectric lead titanate. Through variation of the lead/barium ratio the tetragonal distortion of the lattice cell could be adjusted in a wide range. (orig.)

  10. 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.

  11. Electronic structure of layered ferroelectric high-k titanate Pr{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J.-C. [Materials Research Division, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Troitskaia, I.B. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-11-15

    The spectroscopic parameters and electronic structure of binary titanate Pr{sub 2}Ti{sub 2}O{sub 7} have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr{sub 2}Ti{sub 2}O{sub 7} have been determined as {alpha}{sub Ti}=872.8 and {alpha}{sub O}=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences {Delta}{sub Ti}=(BE O 1s-BE Ti 2p{sub 3/2})=71.6 eV and {Delta}{sub Pr}=BE(Pr 3d{sub 5/2})-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: Black-Right-Pointing-Pointer Solid state synthesis of polar titanate Pr{sub 2}Ti{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Structural and spectroscopic properties and electronic structure determination. Black-Right-Pointing-Pointer Ti-O and Pr-O bonding analysis using Ti 2p{sub 3/2}, Pr 3d{sub 5/2} and O 1s core levels.

  12. Electronic structure of layered ferroelectric high-k titanate La{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V V [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T A [Laboratory of Electron Microscopy and Submicron Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J-C [Materials Research Department, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V G, E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2009-02-07

    The electronic structure of binary titanate La{sub 2}Ti{sub 2}O{sub 7} has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La{sub 2}Ti{sub 2}O{sub 7} are determined as alpha{sub Ti} = 872.4 and alpha{sub O} = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences DELTA{sub Ti} = (BE O 1s - BE Ti 2p{sub 3/2}) = 71.6 eV and DELTA{sub La} = (BE La 3d{sub 5/2} - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  13. X-band EPR studies of ferroelectric lead titanate (PT), piezoelectric lead magnesium niobate (PMN), and PMN/PT powders at 10 and 85 K

    International Nuclear Information System (INIS)

    Huang, J.; Fitzgerald, J.J.; Chasteen, N.D.

    1998-01-01

    X-band EPR spectra of lead titanate (PT) and lead magnesium niobate (PMN) powders prepared by different synthetic methods and a PMN/PT powder of the composition 0.9 PMN/01 PT were obtained at 85 and 10 K. Several EPR signals due to adventitious Fe 3+ ion impurities, a signal due to the Ti 3+ ion, and a signal due to the Pb 3+ ion are observed for PT, PMN, and PMN/PT powders. The EPR signals observed at g = 2.0 and 6.0 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of lad titanate with axial symmetry. The EPR signals observed at g = 1.99 and 4.25 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of PMN and 0.9 PMN/0.1 PT materials with cubic and rhombic symmetries, respectively. The sharp EPR signal observed at g = 1.94 is assigned to Ti 3= ion for PT and 0.9 PMN/0.1 PT powders. In addition, a broader EPR signal at g = 2.28--2.30 for PMN obtained by the molten salt method is assigned to axial Pb 3+ ion sites in this PMN material. EPR results obtained here for the e 3+ ions in the B-sites of the PMN materials, in particular, suggest that both cubic and rhombic symmetry sites corresponding to a range of Nb(OMg) x (ONb) 6-x site configurations exist in the PMN. These EPR results indicate that PMN likely exists with partial B-site cation (Mg/Nb) ordering in the perovskite lattice structure

  14. Photoelectron spectroscopic and microspectroscopic probes of ferroelectrics

    Science.gov (United States)

    Tǎnase, Liviu C.; Abramiuc, Laura E.; Teodorescu, Cristian M.

    2017-12-01

    This contribution is a review of recent aspects connected with photoelectron spectroscopy of free ferroelectric surfaces, metals interfaced with these surfaces, graphene-like layers together with some exemplifications concerning molecular adsorption, dissociations and desorptions occurring from ferroelectrics. Standard photoelectron spectroscopy is used nowadays in correlation with other characterization techniques, such as piezoresponse force microscopy, high resolution transmission electron spectroscopy, and ferroelectric hysteresis cycles. In this work we will concentrate mainly on photoelectron spectroscopy and spectro-microscopy characterization of ferroelectric thin films, starting from atomically clean ferroelectric surfaces of lead zirco-titanate, then going towards heterostructures using this material in combination with graphene-like carbon layers or with metals. Concepts involving charge accumulation and depolarization near surface will be revisited by taking into account the newest findings in this area.

  15. Study of the structure and ferroelectric behavior of BaBi4-xLaxTi4O15 ceramics

    Science.gov (United States)

    Khokhar, Anita; Goyal, Parveen K.; Thakur, O. P.; Sreenivas, K.

    2015-06-01

    The structure and ferroelectric properties of Lanthanum substituted barium bismuth titanate BaBi4-xLaxTi4O15 (0 ≤ x ≤ 0.5) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material. The distribution of lanthanum into the perovskite layers and (Bi2O2)2+ layers of BaBi4Ti4O15 ceramics have been revealed through Raman spectroscopy. At lower value of x, it is seen that La3+ ions prefer to substitute A-site Bi3+ ions in the perovskite layers while for higher x values, La3+ ions get incorporated into the (Bi2O2)2+ layers. A critical La content of x ˜ 0.2 in BaBi4-xLaxTi4O15 is seen to exhibit a large remnant polarization (Pr) with low coercive field (Ec). The improvement in the ferroelectric properties of La substituted BaBi4Ti4O15 ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of lanthanum ion.

  16. Study of the structure, dielectric and ferroelectric behavior of BaBi4+δTi4O15 ceramics

    Science.gov (United States)

    Khokhar, Anita; Goyal, Parveen K.; Thakur, O. P.; Sreenivas, K.

    2016-05-01

    The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi4+δTi4O15 (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (Tm) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (Pr ~ 12.5 µC/cm2), low coercive fields (Ec ~ 26 kV/cm) are measured and a high piezoelectric coefficient (d33 ~ 29 pC/N) is achieved in poled BaBi4Ti4O15 ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi4Ti4O15 ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.

  17. Composition dependence of the ferroelectric properties of lanthanum-modified bismuth titanate thin films grown by using pulsed-laser deposition

    CERN Document Server

    Bu, S D; Park, B H; Noh, T W

    2000-01-01

    Lanthanum-modified bismuth titanate, Bi sub 4 sub - sub x La sub x Ti sub 3 O sub 1 sub 2 (BLT), thin films with a La concentration of 0.25<=x<=1.00 were grown on Pt/Ti/SiO sub 2 /Si substrates by using pulsed-laser deposition. The BLT films showed well-saturated polarization-electric field curves whose remnant polarizations were 16.1 mu C/cm sup 2 , 27.8 mu C/cm sup 2 , 19.6 mu C/cm sup 2 , and 2.7 mu C/cm sup 2 , respectively, for x=0.25, 0.05, 0.75, and 1.00. The fatigue characteristics became better with increasing x up to 0.75. The Au/BLT/Pt capacitor with a La concentration of 0.50 showed an interesting dependence of the remanent polarization on the number of repetitive read/write cycles. On the other hand, the capacitor with a La concentration of 0.75 showed fatigue-free characteristics.

  18. Self-patterning of arrays of ferroelectric capacitors: description by theory of substrate mediated strain interactions

    International Nuclear Information System (INIS)

    Dawber, M; Szafraniak, I; Alexe, M; Scott, J F

    2003-01-01

    Self-patterning presents an appealing alternative to lithography for the production of arrays of nanoscale ferroelectric capacitors for use in high density non-volatile memory devices. However current levels of registration achieved experimentally are far from adequate for this application. To provide a guide for experiment we have applied the theories developed for self-patterning of semiconductor nanocrystals to two self-patterning systems of potential interest for ferroelectric memory applications, metallic bismuth oxide on bismuth titanate and ferroelectric lead zirconate titanate on strontium titanate. (letter to the editor)

  19. Barium Sulfate

    Science.gov (United States)

    ... uses a computer to put together x-ray images to create cross-sectional or three dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called radiopaque contrast media. It works by coating the esophagus, stomach, or ...

  20. Ferroelectric plasma sources for NDCX-II and heavy ion drivers

    Energy Technology Data Exchange (ETDEWEB)

    Gilson, E.P., E-mail: egilson@pppl.gov [Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey, 08543 (United States); Davidson, R.C.; Efthimion, P.C.; Kaganovich, I.D. [Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey, 08543 (United States); Kwan, J.W.; Lidia, S.M.; Ni, P.A.; Roy, P.K.; Seidl, P.A.; Waldron, W.L. [Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California, 94720 (United States); Barnard, J.J.; Friedman, A. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California, 94550 (United States)

    2014-01-01

    A barium titanate ferroelectric cylindrical plasma source has been developed, tested and delivered for the Neutralized Drift Compression Experiment NDCX-II at Lawrence Berkeley National Laboratory (LBNL). The plasma source design is based on the successful design of the NDCX-I plasma source. A 7 kV pulse applied across the 3.8 mm-thick ceramic cylinder wall produces a large polarization surface charge density that leads to breakdown and plasma formation. The plasma that fills the NDCX-II drift section upstream of the final-focusing solenoid has a plasma number density exceeding 10{sup 10} cm{sup −3} and an electron temperature of several eV. The operating principle of the ferroelectric plasma source are reviewed and a detailed description of the installation plans is presented. The criteria for plasma sources with larger number density will be given, and concepts will be presented for plasma sources for driver applications. Plasma sources for drivers will need to be highly reliable, and operate at several Hz for millions of shots.

  1. 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

  2. Barite (Barium)

    Science.gov (United States)

    Johnson, Craig A.; Piatak, Nadine M.; Miller, M. Michael; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Barite (barium sulfate, BaSO4) is vital to the oil and gas industry because it is a key constituent of the mud used to drill oil and gas wells. Elemental barium is an additive in optical glass, ceramic glazes, and other products. Within the United States, barite is produced mainly from mines in Nevada. Imports in 2011 (the latest year for which complete data were available) accounted for 78 percent of domestic consumption and came mostly from China.Barite deposits can be divided into the following four main types: bedded-sedimentary; bedded-volcanic; vein, cavity-fill, and metasomatic; and residual. Bedded-sedimentary deposits, which are found in sedimentary rocks with characteristics of high biological productivity during sediment accumulation, are the major sources of barite production and account for the majority of reserves, both in the United States and worldwide. In 2013, China and India were the leading producers of barite, and they have large identified resources that position them to be significant producers for the foreseeable future. The potential for undiscovered barite resources in the United States and in many other countries is considerable, however. The expected tight supply and rising costs in the coming years will likely be met by increased production from such countries as Kazakhstan, Mexico, Morocco, and Vietnam.Barium has limited mobility in the environment and exposed barium in the vicinity of barite mines poses minimal risk to human or ecosystem health. Of greater concern is the potential for acidic metal-bearing drainage at sites where the barite ores or waste rocks contain abundant sulfide minerals. This risk is lessened naturally if the host rocks at the site are acid-neutralizing, and the risk can also be lessened by engineering measures.

  3. Mechanical niobium doping in barium titanate electroceramics

    Energy Technology Data Exchange (ETDEWEB)

    Velasco-Davalos, I.A., E-mail: ivan.velascodavalos@gmail.com [Departmento de Ingeniería Metalúrgica, Instituto Politécnico Nacional, Zacatenco, 07338 México D.F. (Mexico); INRS-EMT, 1650 Boul. Lionel-Boulet, Varennes J3X 1S2 (Canada); Ruediger, A. [INRS-EMT, 1650 Boul. Lionel-Boulet, Varennes J3X 1S2 (Canada); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Av. Sierra Leona 550, Lomas, 78210 S.L.P. (Mexico); Gomez-Yanez, C. [Departmento de Ingeniería Metalúrgica, Instituto Politécnico Nacional, Zacatenco, 07338 México D.F. (Mexico)

    2013-12-25

    Highlights: •We demonstrate a new doping procedure by Mechanical Alloying (MA). •For small dopant concentrations, charge compensation of Nb is primarily attributed to free electrons. •At higher Nb concentrations cation vacancies prevail as compensation mechanism. -- Abstract: Niobium is a well-established donor dopant for semi-conducting BaTiO{sub 3} ceramics. The conventional procedure to dissolve Nb into BaTiO{sub 3} relies on thermal activation at high temperatures (up to 1500 °C) and even then, large dwell times are necessary due to the small diffusion coefficients of Nb{sup 5+}. In this work, we demonstrate a new doping procedure by Mechanical Alloying (MA), which has already proven its potential for the fabrication of conductive electroceramics. In a planetary mill, powders of BaTiO{sub 3} and Nb{sub 2}O{sub 5} were mixed for up to 540 min. The BaTiO{sub 3} unit cell volume increases with increasing Nb concentration. The electrical properties of conventional and mechanical alloyed samples as a function of Nb concentration are similar, however the mechanically alloyed samples shows a large conductivity that we attribute to a better homogeneity in the structure of MA-processed samples. For small dopant concentrations, charge compensation of the pentavalent Nb is primarily attributed to free electrons. At higher Nb concentrations cation vacancies prevail as compensation mechanism.

  4. Electrical characterization of zirconium substituted barium titanate ...

    Indian Academy of Sciences (India)

    been used as a tool to analyse electrical properties of the sample as a function of frequency and ... tures were thoroughly ground in an agate mortar and passed ... disk shaped pellets. ... Figure 2 shows variation of imaginary part of impedance.

  5. Electrical characterization of zirconium substituted barium titanate ...

    Indian Academy of Sciences (India)

    Nyquist (Cole–Cole) plots show both inter and intra grain boundary ... talline solids in a wide range of frequencies and temperature. ... measurements were carried out using a precision. LCR meter (HP 4284A) at an oscillation amplitude of 1 V. Impedance measurements were carried out in the tempera- ture range of 300.

  6. Study of the structure, dielectric and ferroelectric behavior of BaBi{sub 4+δ}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Anita, E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Goyal, Parveen K., E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi-110 007 (India); Thakur, O. P. [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi 110 054 (India)

    2016-05-23

    The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi{sub 4+δ}Ti{sub 4}O{sub 15} (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (T{sub m}) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (P{sub r} ~ 12.5  µC/cm{sup 2}), low coercive fields (E{sub c} ~ 26 kV/cm) are measured and a high piezoelectric coefficient (d{sub 33} ~ 29 pC/N) is achieved in poled BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.

  7. Study of the structure, dielectric and ferroelectric behavior of BaBi_4_+_δTi_4O_1_5 ceramics

    International Nuclear Information System (INIS)

    Khokhar, Anita; Goyal, Parveen K.; Sreenivas, K.; Thakur, O. P.

    2016-01-01

    The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi_4_+_δTi_4O_1_5 (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (T_m) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (P_r ~ 12.5  µC/cm"2), low coercive fields (E_c ~ 26 kV/cm) are measured and a high piezoelectric coefficient (d_3_3 ~ 29 pC/N) is achieved in poled BaBi_4Ti_4O_1_5 ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi_4Ti_4O_1_5 ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.

  8. Study of the structure and ferroelectric behavior of BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Anita, E-mail: mails4anita@gmail.com; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi-110 007 (India); Goyal, Parveen K. [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)

    2015-06-24

    The structure and ferroelectric properties of Lanthanum substituted barium bismuth titanate BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} (0 ≤ x ≤ 0.5) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material. 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 have been revealed through Raman spectroscopy. At lower value of x, it is seen that La{sup 3+} ions prefer to substitute A-site Bi{sup 3+} ions in the perovskite layers while for higher x values, La{sup 3+} ions get incorporated into the (Bi{sub 2}O{sub 2}){sup 2+} layers. A critical La content of x ∼ 0.2 in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} is seen to exhibit a large remnant polarization (P{sub r}) with low coercive field (E{sub c}). The improvement in the ferroelectric properties of La substituted BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of lanthanum ion.

  9. Ferroelectric devices

    CERN Document Server

    Uchino, Kenji

    2009-01-01

    Updating its bestselling predecessor, Ferroelectric Devices, Second Edition assesses the last decade of developments-and setbacks-in the commercialization of ferroelectricity. Field pioneer and esteemed author Uchino provides insight into why this relatively nascent and interdisciplinary process has failed so far without a systematic accumulation of fundamental knowledge regarding materials and device development.Filling the informational void, this collection of information reviews state-of-the-art research and development trends reflecting nano and optical technologies, environmental regulat

  10. Transparent Ferroelectric Capacitors on Glass

    Directory of Open Access Journals (Sweden)

    Daniele Sette

    2017-10-01

    Full Text Available We deposited transparent ferroelectric lead zirconate titanate thin films on fused silica and contacted them via Al-doped zinc oxide (AZO transparent electrodes with an interdigitated electrode (IDE design. These layers, together with a TiO2 buffer layer on the fused silica substrate, are highly transparent (>60% in the visible optical range. Fully crystallized Pb(Zr0.52Ti0.48O3 (PZT films are dielectrically functional and exhibit a typical ferroelectric polarization loop with a remanent polarization of 15 μC/cm2. The permittivity value of 650, obtained with IDE AZO electrodes is equivalent to the one measured with Pt electrodes patterned with the same design, which proves the high quality of the developed transparent structures.

  11. The behaviour of the ferroelectric ceramics: BaTiO3, Pb(Zr,Ti)O3 and Pb(Sn,Zr,Ti)O3 When hit by a projectile from a 30 mm bore gun

    International Nuclear Information System (INIS)

    David, Jean

    1971-10-01

    The liberation of the electrical charges and energy stored in a ferroelectric material as a result of induced dynamic pressure was studied. The pressure was generated by the impact of a cylindrical projectile fired from a special 30 mm bore gun. A brief description of the gun, experimental set up, and the measurements made is given. It was shown that below a certain pressure P Emax , corresponding to the maximum energy liberated, barium titanate and PZT materials behave similarly. The maximum energy obtained with a PZT 95/5 material, was 700 mJ/cm 3 and was dissipated in a 5 Ω resistance. It is expected that improved material compositions will allow an energy density higher than 1 J /cm 3 to be reached [fr

  12. BARIUM RECOVERY PROCESS

    Science.gov (United States)

    Blanco, R.E.

    1959-07-21

    A method of separating barium from nuclear fission products is described. In accordance with the invention, barium may be recovered from an acidic solution of neutron-irradiated fissionable material by carrying ihe barium cut of solution as a sulfate with lead as a carrier and then dissolving the barium-containing precipitate in an aqueous solution of an aliphatic diamine chelating reagent. The barium values together with certain other metallic values present in the diamine solution are then absorbed onto a cation exchange resin and the barium is selectively eluted from the resin bed with concentrated nitric acid.

  13. Magnetic enhancement of ferroelectric polarization in a self-grown ferroelectric-ferromagnetic composite

    Science.gov (United States)

    Kumar, Amit; Narayan, Bastola; Pachat, Rohit; Ranjan, Rajeev

    2018-02-01

    Ferroelectric-ferromagnetic multiferroic composites are of great interest both from the scientific and technological standpoints. The extent of coupling between polarization and magnetization in such two-phase systems depends on how efficiently the magnetostrictive and electrostrictive/piezoelectric strain gets transferred from one phase to the other. This challenge is most profound in the easy to make 0-3 ferroelectric-ferromagnetic particulate composites. Here we report a self-grown ferroelectric-ferromagnetic 0-3 particulate composite through controlled spontaneous precipitation of ferrimagnetic barium hexaferrite phase (BaF e12O19 ) amid ferroelectric grains in the multiferroic alloy system BiFe O3-BaTi O3 . We demonstrate that a composite specimen exhibiting merely ˜1% hexaferrite phase exhibits ˜34% increase in saturation polarization in a dc magnetic field of ˜10 kOe. Using modified Rayleigh analysis of the polarization field loop in the subcoercive field region we argue that the substantial enhancement in the ferroelectric switching is associated with the reduction in the barrier heights of the pinning centers of the ferroelectric-ferroelastic domain walls in the stress field generated by magnetostriction in the hexaferrite grains when the magnetic field is turned on. Our study proves that controlled precipitation of the magnetic phase is a good strategy for synthesis of 0-3 ferroelectric-ferromagnetic particulate multiferroic composite as it not only helps in ensuring a good electrical insulating character of the composite, enabling it to sustain high enough electric field for ferroelectric switching, but also the factors associated with the spontaneity of the precipitation process ensure efficient transfer of the magnetostrictive strain/stress to the surrounding ferroelectric matrix making domain wall motion easy.

  14. Structure and multiferroic properties of barium hexaferrite ceramics

    International Nuclear Information System (INIS)

    Tan, Guolong; Chen, Xiuna

    2013-01-01

    Simultaneous occurrence of large ferroelectricity and strong ferromagnetism have been observed in barium hexaferrite ceramics. Barium hexaferrite (BaFe 12 O 19 ) powders with hexagonal crystal structure were successfully synthesized in a polymer precursor method using barium acetate and ferric acetylacetonate as the precursors. The powders were pressed into pellets which were sintered into ceramics at 1200 °C and 1300 °C for 1 h. The structure and morphology of the ceramics were examined using X-ray diffraction and field emission scanning electron microscopy. Large spontaneous polarization was observed in the BaFe 12 O 19 ceramics at room temperature, revealing a clear ferroelectric hysteresis loop. The maximum remanent polarization of the BaFe 12 O 19 ceramic was estimated approximately 11.8 μC cm −2 . The FeO 6 octahedron in its perovskite-like hexagonal unit cell and the shift of Fe 3+ off the center of octahedron are suggested to be the origin of the polarization in BaFe 12 O 19 . The BaFe 12 O 19 ceramics also showed strong ferromagnetism at room temperature. - Graphical abstract: Ferroelectric hysteresis loops of BaFe 12 O 19 ceramics measured at a frequency of 120 Hz, which shows that the ceramics sintered at 1200 °C is ferroelectric with P r ∼11.8 μC/cm 2 . Highlights: ► Large ferroelectricity and strong ferromagnetism were observed in barium hexaferrite ceramics. ► The maximum remanent polarization of the BaFe 12 O 19 ceramic was estimated to be 11.8 μC cm −2 . ► The FeO 6 octahedron and off-center shift of Fe 3+ are suggested to be the origin of the polarization.

  15. Barium enema (image)

    Science.gov (United States)

    A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...

  16. Low-loss microelectrodes fabricated using reverse-side exposure for a tunable ferroelectric capacitor application

    Science.gov (United States)

    Yoon, Yong-Kyu; Stevenson Kenney, J.; Hunt, Andrew T.; Allen, Mark G.

    2006-02-01

    Narrowly spaced thick microelectrodes are fabricated using a self-aligned multiple reverse-side exposure scheme for an improved quality-factor tunable ferroelectric capacitor. The microelectrodes are fabricated on a functional substrate—a thin film ferroelectric (barium strontium titanate, BST; BaxSr1-xTiO3) coated sapphire substrate, which has an electric-field-dependent dielectric property providing tuning functionality, as well as UV transparency permitting an additional degree of freedom in photolithography steps. The microelectrode process has been applied to interdigitated capacitor fabrication, where a critical challenge is maintaining narrow gaps between electrodes for high tunability, while simultaneously forming thick electrodes to minimize conductor loss. A single mask, self-aligned reverse-side exposure through the transparent substrate achieves both these goals. A single-finger test capacitor with an electrode gap of 1.2 µm and an electrode thickness of 2.2 µm is fabricated and characterized. Tunability (T = 100 × (C0 - Cbias)/C0) of 33% at 10 V has been achieved at 100 kHz. The 2.2 µm thick structure shows improvement of Q-factor compared to that of a 0.1 µm thick structure. To demonstrate the scalability of this process, a 102-finger interdigitated capacitor is fabricated and characterized at 100 kHz and 1 GHz. The structure is embedded in a 25 µm thick epoxy resin SU-8 for passivation. A quality factor decrease of 15-25%, tunability decrease of 2-3% and capacitance increase of 6% are observed due to the expoxy resin after passivation. High frequency performance of the capacitor has been measured to be 15.9 pF of capacitance, 28.1% tunability at 10 V and a quality factor of 16 (at a 10 V dc bias) at 1 GHz.

  17. 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.)

  18. Microstructure of lead zirconium titanate (PZT) by electron microscopy

    International Nuclear Information System (INIS)

    Bursill, L.A.; Peng JuLin

    1989-01-01

    Transmission and high-resolution electron microscopy reveal the microtexture of lead zirconium titanate ceramics. Fine scale (≤ 500 Aangstroem) ferroelastic and ferroelectric twin domains, as well as dislocations were found in a complex texture. Correlations between stoichiometry, microstructure and piezoelectric properties are discussed. 6 refs., 3 figs

  19. Pyroelectricity versus conductivity in soft lead zirconate titanate (PZT) ceramics

    NARCIS (Netherlands)

    Kamel, T.M.; With, de G.

    2007-01-01

    The electrical behavior of modified soft lead zirconate titanate (PZT) ceramics has been studied as a function of temperature at different direct current (dc) electric fields and grain sizes. As ferroelectrics, such as PZT, are highly polarizable materials, poling, depolarization, and electric

  20. Frequency and Temperature Dependent Dielectric Properties of Free-standing Strontium Titanate Thin Films.

    Science.gov (United States)

    Dalberth, Mark J.; Stauber, Renaud E.; Anderson, Britt; Price, John C.; Rogers, Charles T.

    1998-03-01

    We will report on the frequency and temperature dependence of the complex dielectric function of free-standing strontium titanate (STO) films. STO is an incipient ferroelectric with electric-field tunable dielectric properties of utility in microwave electronics. The films are grown epitaxially via pulsed laser deposition on a variety of substrates, including lanthanum aluminate (LAO), neodymium gallate (NGO), and STO. An initial film of yttrium barium cuprate (YBCO) is grown on the substrate, followed by deposition of the STO layer. Following deposition, the sacrificial YBCO layer is chemically etched away in dilute nitric acid, leaving the substrate and a released, free-standing STO film. Coplanar capacitor structures fabricated on the released films allow us to measure the dielectric response. We observe a peak dielectric function in excess of 5000 at 35K, change in dielectric constant of over a factor of 8 for 10Volt/micron electric fields, and temperature dependence above 50K that is very similar to bulk material. The dielectric loss shows two peaks, each with a thermally activated behavior, apparently arising from two types of polar defects. We will discuss the correlation between dielectric properties, growth conditions, and strain in the free-standing STO films.

  1. Ferroelectric ultrathin perovskite films

    Science.gov (United States)

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  2. Characteristics of 5 mol% Ce{sup 3+}-doped barium titanate nanowires prepared by a combined route involving sol–gel chemistry and polycarbonate membrane-templated process

    Energy Technology Data Exchange (ETDEWEB)

    Vasilescu, Catalina-Andreea [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania); Trupina, Lucian [National Institute of Materials Physics (Romania); Vasile, Bogdan Stefan [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania); Trusca, Roxana [S.C. METAV–Research & Development Bucharest (Romania); Cernea, Marin [National Institute of Materials Physics (Romania); Ianculescu, Adelina-Carmen, E-mail: a-ianculescu@yahoo.com [University POLITEHNICA of Bucharest, Department of Oxide Materials Science and Engineering (Romania)

    2015-11-15

    Ba{sub 0.95}Ce{sub 0.05}Ti{sub 0.9875}O{sub 3} nanowires were fabricated by sol–gel method using as template a polycarbonate membrane with channels of 100 nm diameter. FE-SEM analyses showed that continuous gel wires of length up to 17 µm and an average diameter of 81 nm, were obtained. After calcination at 700 °C for 1 h, these green 1D nanostructures were converted into well-crystallised wires with an average diameter of 59.7 nm, as high-resolution transmission electron microscopy and selected area electron diffraction indicated. The piezoelectric activity of the Ba{sub 0.95}Ce{sub 0.05}Ti{sub 0.9875}O{sub 3} nanowires was investigated using piezoresponse force microscopy (PFM) correlated with atomic force microscopy. The results of PFM measurements indicated that the wires exhibit a significant fraction of ferroelectric domains larger than the grains size and a good piezoelectric response.

  3. Determination of the Steady State Leakage Current in Structures with Ferroelectric Ceramic Films

    Science.gov (United States)

    Podgornyi, Yu. V.; Vorotilov, K. A.; Sigov, A. S.

    2018-03-01

    Steady state leakage currents have been investigated in capacitor structures with ferroelectric solgel films of lead zirconate titanate (PZT) formed on silicon substrates with a lower Pt electrode. It is established that Pt/PZT/Hg structures, regardless of the PZT film thickness, are characterized by the presence of a rectifying contact similar to p-n junction. The steady state leakage current in the forward direction increases with a decrease in the film thickness and is determined by the ferroelectric bulk conductivity.

  4. Effect of SiO2/B2O3 Ratio on the Crystallization Behavior and Dielectric Properties of Barium Strontium Titanate Glass-Ceramics Prepared by Sol-Gel Process

    Science.gov (United States)

    Chen, Yongzhou; Zhang, Yong; Song, Xiaozhen; Shen, Ziqin; Zhang, Tianyuan

    2018-05-01

    Ferroelectric glass-ceramics, with a basic composition 90 wt.% (Ba0.65Sr0.35)TiO3-10 wt.% (B2O3-nSiO2) (n = 0.5, 1, 3, 5) were synthesized by the sol-gel method and their phase development and dielectric properties were investigated by differential thermal analysis, x-ray diffraction, field emission scanning electron microscopy, dielectric temperature curves and impedance spectroscopy. From the differential thermal analysis, glass transition and crystallization behavior can be observed. From the x-ray diffraction study, two crystalline phases (Ba,Sr)TiO3 and Ba2TiSi2O8 were formed over the entire composition range of the glass-ceramics. In addition, the main crystal phase has undergone a transformation from (Ba,Sr)TiO3 to Ba2TiSi2O8 with the increase of n. A typical structure in which the crystal phase was surrounded by a glassy matrix has been observed in the scanning electron microscope images. As a result of temperature dependent dielectric property measurements, the dielectric constant increased obviously with the increase of n from 0.5 to 1. Further increasing n led to a reduction of the dielectric constant, which is in coincidence with the variation of the intensity of (Ba,Sr)TiO3 phase with n. According to the impedance spectroscopy analysis and the activation energy calculation, the relaxation peak in both Z″ and M″ data should be attributed to the crystal-glass interface, and the change of conduction mechanism with the increase of SiO2/B2O3 ratio may be attributed to the corresponding transition of the main crystal phase.

  5. Tunability, dielectric, and piezoelectric properties of Ba{sub (1−x)}Ca{sub x}Ti{sub (1−y)}Zr{sub y}O{sub 3} ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Daumont, C. J. M., E-mail: christophe.daumont@univ-tours.fr; Le Mouellic, E.; Negulescu, B.; Wolfman, J. [Laboratoire GREMAN, UMR7347 CNRS, Faculté de Sciences et Techniques, Université François Rabelais, 37200 Tours (France); Simon, Q.; Payan, S.; Maglione, M. [Institute of Condensed Matter Chemistry of Bordeaux, ICMCB-CNRS, Université de Bordeaux, 33608 Pessac Cedex (France); Gardes, P.; Poveda, P. [STMicroelectronics, 10 rue Thalès de Milet, 37071 Tours Cedex (France)

    2016-03-07

    Tunable ferroelectric capacitors, which exhibit a decrease of the dielectric permittivity (ϵ) under electric field, are widely used in electronics for RF tunable applications (e.g., antenna impedance matching). Current devices use barium strontium titanate as the tunable dielectric, and the need for performance enhancement of the tunable element is the key for device improvement. We report here on libraries of Ba{sub 0.97}Ca{sub 0.03}Ti{sub 1−x}Zr{sub x}O{sub 3} thin films (0 ≤ x ≤ 27%) with a thickness of about 130 nm deposited on IrO{sub 2}/SiO{sub 2}/Si substrates using combinatorial pulsed laser deposition allowing for gradients of composition on one sample. A total of 600 capacitors on a single sample were characterized in order to statistically investigate the dielectric properties. We show that the tunabilty is maximum at intermediate compositions, reaching values up to 60% for an electric field of about 400 kV cm{sup −1}. We attribute the high tunability in the intermediate compositions to the paraelectric-ferroelectric phase transition, which is brought down to room temperature by the addition of Zr. In addition, the piezoelectric coefficient is found to be decreasing with increasing Zr content.

  6. Electrical and thermal properties of lead titanate glass ceramics

    International Nuclear Information System (INIS)

    Shankar, J.; Deshpande, V.K.

    2011-01-01

    Glass samples with composition of (50-X)PbO-(25+X)TiO 2 -25B 2 O 3 (where X=0, 5, 10 and 12.5 mol%) were prepared using conventional quenching technique. The glass transition temperature, T g and crystallization temperature T c were determined from the DTA. These glass samples were converted to glass ceramics by following two stage heat treatment schedule. The glass ceramic samples were characterized by XRD, SEM and dielectric constant measurements. The XRD results revealed the formation of ferroelectric lead titanate (PT) as a major crystalline phase in the glass ceramics. The density increases and the CTE decreases for all glass ceramics with increase in X (mol%). This may be attributed to increase in PT phase. The SEM results which show rounded crystallites of lead titanate, also supports other results. Hysteresis loops observed at room temperature confirms the ferroelectric nature of glass ceramics. The optimized glass ceramic sample exhibits high dielectric constant which is of technical importance. -- Research Highlights: →Lead titanate glass ceramics prepared by conventional quenching technique. →Lead titanate is a major crystalline phase in the glass ceramics. →The ferroelectric nature of glass ceramics is confirmed by the hysteresis study. →The high value of ε observed at room temperature is quite promising in the study.

  7. Multilayer-WS2:ferroelectric composite for ultrafast tunable metamaterial-induced transparency applications

    Science.gov (United States)

    Yang, Xiaoyu; Yang, Jinghuan; Hu, Xiaoyong; Zhu, Yu; Yang, Hong; Gong, Qihuang

    2015-08-01

    An ultrafast and low-power all-optical tunable metamaterial-induced transparency is realized, using polycrystalline barium titanate doped gold nanoparticles and multilayer tungsten disulfide microsheets as nonlinear optical materials. Large nonlinearity enhancement is obtained associated with quantum confinement effect, local-field effect, and reinforced interaction between light and multilayer tungsten disulfide. Low threshold pump intensity of 20 MW/cm2 is achieved. An ultrafast response time of 85 ps is maintained because of fast carrier relaxation dynamics in nanoscale crystal grains of polycrystalline barium titanate. This may be useful for the study of integrated photonic devices based on two-dimensional materials.

  8. Multilayer-WS2:ferroelectric composite for ultrafast tunable metamaterial-induced transparency applications

    International Nuclear Information System (INIS)

    Yang, Xiaoyu; Yang, Jinghuan; Zhu, Yu; Yang, Hong; Hu, Xiaoyong; Gong, Qihuang

    2015-01-01

    An ultrafast and low-power all-optical tunable metamaterial-induced transparency is realized, using polycrystalline barium titanate doped gold nanoparticles and multilayer tungsten disulfide microsheets as nonlinear optical materials. Large nonlinearity enhancement is obtained associated with quantum confinement effect, local-field effect, and reinforced interaction between light and multilayer tungsten disulfide. Low threshold pump intensity of 20 MW/cm 2 is achieved. An ultrafast response time of 85 ps is maintained because of fast carrier relaxation dynamics in nanoscale crystal grains of polycrystalline barium titanate. This may be useful for the study of integrated photonic devices based on two-dimensional materials

  9. Synthesis of ferroelectric nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Roervik, Per Martin

    2008-12-15

    The increasing miniaturization of electric and mechanical components makes the synthesis and assembly of nanoscale structures an important step in modern technology. Functional materials, such as the ferroelectric perovskites, are vital to the integration and utility value of nanotechnology in the future. In the present work, chemical methods to synthesize one-dimensional (1D) nanostructures of ferroelectric perovskites have been studied. To successfully and controllably make 1D nanostructures by chemical methods it is very important to understand the growth mechanism of these nanostructures, in order to design the structures for use in various applications. For the integration of 1D nanostructures into devices it is also very important to be able to make arrays and large-area designed structures from the building blocks that single nanostructures constitute. As functional materials, it is of course also vital to study the properties of the nanostructures. The characterization of properties of single nanostructures is challenging, but essential to the use of such structures. The aim of this work has been to synthesize high quality single-crystalline 1D nanostructures of ferroelectric perovskites with emphasis on PbTiO3 , to make arrays or hierarchical nanostructures of 1D nanostructures on substrates, to understand the growth mechanisms of the 1D nanostructures, and to investigate the ferroelectric and piezoelectric properties of the 1D nanostructures. In Paper I, a molten salt synthesis route, previously reported to yield BaTiO3 , PbTiO3 and Na2Ti6O13 nanorods, was re-examined in order to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titanium was annealed in the presence of NaCl at 760 degrees Celsius or 820 degrees Celsius. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was

  10. Modified titanate perovskites in photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Wlodarczak, M.; Ludwiczak, M.; Laniecki, M. [A. Mickiewicz Univ. (Poland)

    2010-07-01

    Received materials have structure of perovskite, what was shown by XRD diffraction patterns. Perovskite structure is present in all samples with strontium, barium and one sample with calcium. Moreover, received barium and strontium titanate are very similar to pattern materials. XRD results show, that temperature 500 C is too low to create perovskite structure in CaTiO{sub 3}. However, it is high enough in case of SrTiO{sub 3} and BaTiO{sub 3}. One regularity is obvious, surface area increases for samples calcined in lower temperature. There is a connection between surface area and dispersion of platinum. Both of them reach the greatest value to the calcium titanate. Catalytic activity was shown by all of received samples. Measurable values were received to samples calcined in 700 C. Calcium titanate had the best catalytic activity, both an amount of hydrogen and a ratio of hydrogen to platinum. There is one regularity to all samples, the ration of hydrogen to platinum increase when amount of platinum decrease. (orig.)

  11. Dielectric behaviors of lead zirconate titanate ceramics with coplanar electrodes

    International Nuclear Information System (INIS)

    Wang, Y.; Cheng, Y.L.; Zhang, Y.W.; Chan, H.L.W.; Choy, C.L.

    2003-01-01

    This paper reports on the dielectric behaviors of lead zirconate titanate (PZT) capacitors with coplanar electrodes. Usually a ferroelectric device has a metal-ferroelectric-metal configuration (parallel plate capacitor); when both the electrodes are on one side of a ceramic to form a coplanar capacitor, different dielectric behaviors will be anticipated because of the change in the distribution of the test field inside the dielectrics. This paper describes how the capacitance and dielectric loss of PZT-based coplanar capacitors change with electrode distance, area and test frequency

  12. Crystallinity and electrical properties of neodymium-substituted bismuth titanate thin films

    International Nuclear Information System (INIS)

    Chen, Y.-C.; Hsiung, C.-P.; Chen, C.-Y.; Gan, J.-Y.; Sun, Y.-M.; Lin, C.-P.

    2006-01-01

    We report on the properties of Nd-substituted bismuth titanate Bi 4-x Nd x Ti 3 O 12 (BNdT) thin films for ferroelectric non-volatile memory applications. The Nd-substituted bismuth titanate thin films fabricated by modified chemical solution deposition technique showed much improved properties compared to pure bismuth titanate. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 640 deg. C and grain size was found to be considerably increased as the annealing temperature increased. The film properties were found to be strongly dependent on the Nd content and annealing temperatures. The measured dielectric constant of BNdT thin films was in the range 172-130 for Bi 4-x Nd x Ti 3 O 12 with x 0.0-0.75. Ferroelectric properties of Nd-substituted bismuth titanate thin films were significantly improved compared to pure bismuth titanate. For example, the observed 2P r and E c for Bi 3.25 Nd 0.75 Ti 3 O 12 , annealed at 680 deg. C, were 38 μC/cm 2 and 98 kV/cm, respectively. The improved microstructural and ferroelectric properties of BNdT thin films suggest their suitability for high density ferroelectric random access memory applications

  13. Aspiration of Barium Contrast

    OpenAIRE

    Fuentes Santos, Cristina; Steen, Bárbara

    2014-01-01

    The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical fil...

  14. Piezoelectric Response of Ferroelectric Ceramics Under Mechanical Stress

    Science.gov (United States)

    2015-09-17

    response of the bulk Barium Titanate-based dielectric in such capacitors has not yet been addressed for shocks above 3,000 g. Thus, the current research...3.15 Low Voltage Capacitor Dielectric Volume Sections . . . . . . . . . . . . . . . 81 3.16 Electrodes, Terminals and Boundary Condition Surfaces...Final Separation from the Flexing Board of 1812 Capacitor after 36-inch Drop . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 4.21 Dielectric

  15. Two-dimensional ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L M; Fridkin, Vladimir M; Palto, Sergei P [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation); Bune, A V; Dowben, P A; Ducharme, Stephen [Department of Physics and Astronomy, Behlen Laboratory of Physics, Center for Materials Research and Analysis, University of Nebraska-Linkoln, Linkoln, NE (United States)

    2000-03-31

    The investigation of the finite-size effect in ferroelectric crystals and films has been limited by the experimental conditions. The smallest demonstrated ferroelectric crystals had a diameter of {approx}200 A and the thinnest ferroelectric films were {approx}200 A thick, macroscopic sizes on an atomic scale. Langmuir-Blodgett deposition of films one monolayer at a time has produced high quality ferroelectric films as thin as 10 A, made from polyvinylidene fluoride and its copolymers. These ultrathin films permitted the ultimate investigation of finite-size effects on the atomic thickness scale. Langmuir-Blodgett films also revealed the fundamental two-dimensional character of ferroelectricity in these materials by demonstrating that there is no so-called critical thickness; films as thin as two monolayers (1 nm) are ferroelectric, with a transition temperature near that of the bulk material. The films exhibit all the main properties of ferroelectricity with a first-order ferroelectric-paraelectric phase transition: polarization hysteresis (switching); the jump in spontaneous polarization at the phase transition temperature; thermal hysteresis in the polarization; the increase in the transition temperature with applied field; double hysteresis above the phase transition temperature; and the existence of the ferroelectric critical point. The films also exhibit a new phase transition associated with the two-dimensional layers. (reviews of topical problems)

  16. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.; Zidan, Mohammed A.; Al-Nassar, Mohammed Y.; Hanna, Amir; Kosel, Jü rgen; Salama, Khaled N.; Hussain, Muhammad Mustafa

    2015-01-01

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational

  17. Conformal growth method of ferroelectric materials for multifunctional composites

    Science.gov (United States)

    Bowland, Christopher Charles

    Multifunctional composites are the next generation of composites and aim to simultaneously meet multiple performance objectives to create system-level performance enhancements. Current fiber-reinforced composites have offered improved efficiency and performance through weight reduction and increased strength. However, these composites satisfy singular performance objectives. Therefore, the concept of multifunctional composites was developed as an approach to create components in a system that serve multiple functions. These composites aim to reduce the required components in a system by integrating unifunctional components together thus reducing the weight and complexity of the system as a whole. This work offers an approach to create multifunctional composites through the development of a structural, multifunctional fiber. This is achieved by synthesizing a ferroelectric material on the surface of carbon fiber. In this work, a two-step hydrothermal reaction is developed for synthesizing a conformal film of barium titanate (BaTiO3) on the surface of carbon fiber. A fundamental understanding of this hydrothermal process is performed on planar substrates leading to the development of processing parameters that result in epitaxial-type growth of highly-aligned BaTiO3 nanowires. This work establishes the hydrothermal reaction as a powerful synthesis technique for generating nanostructured BaTiO3 on carbon fiber creating a novel, multifunctional fiber. A reaction optimization process leads to the development of parameters that stabilize tetragonal phase BaTiO3 without the need for subsequent heat treatments. The application potential of these fibers is illustrated with both single fibers and woven fabrics. Single fiber cantilever beams are fabricated and subjected to vibrations to determine its voltage output with the ultimate goal of producing an air flow sensor. Carbon fiber reinforced composite integration is carried out by scaling up the hydrothermal reaction to

  18. Barium granuloma of the rectum: case report

    International Nuclear Information System (INIS)

    Kim, Dae Jin; Kim, Se Hyung; Jeoung, Ah Young; Lee, Kyoung Ho; Choi, Byung Ihn; Han, Joon Koo

    2003-01-01

    Barium granulomas usually occur after barium enema within 8 cm of the anal verge probably due to minute laceration of rectal wall by enema tip and extravasation of barium during barium enema. We report a case of barium granuloma of rectum in a 47-year-old man, who did not have history of barium enema. In rare instance, barium granuloma can occur without a history of barium enema and careful interpretation of radiologic image is essential to make a correct diagnosis

  19. Modeling and minimization of barium sulfate scale

    Science.gov (United States)

    Alan W. Rudie; Peter W. Hart

    2006-01-01

    The majority of the barium present in the pulping process exits the digester as barium carbonate. Barium carbonate dissolves in the bleach plant when the pH drops below 7 and, if barium and sulfate concentrations are too high, begins to precipitate as barium sulfate. Barium is difficult to control because a mill cannot avoid this carbonate-to-sulfate transition using...

  20. Nano-embossing technology on ferroelectric thin film Pb(Zr0.3,Ti0.7O3 for multi-bit storage application

    Directory of Open Access Journals (Sweden)

    Lu Qian

    2011-01-01

    Full Text Available Abstract In this work, we apply nano-embossing technique to form a stagger structure in ferroelectric lead zirconate titanate [Pb(Zr0.3, Ti0.7O3 (PZT] films and investigate the ferroelectric and electrical characterizations of the embossed and un-embossed regions, respectively, of the same films by using piezoresponse force microscopy (PFM and Radiant Technologies Precision Material Analyzer. Attributed to the different layer thickness of the patterned ferroelectric thin film, two distinctive coercive voltages have been obtained, thereby, allowing for a single ferroelectric memory cell to contain more than one bit of data.

  1. Multiple electrical phase transitions in Al substituted barium hexaferrite

    Science.gov (United States)

    Kumar, Sunil; Supriya, Sweety; Kar, Manoranjan

    2017-12-01

    Barium hexaferrite is known to be a very good ferromagnetic material. However, it shows very good dielectric properties, i.e., the dielectric constant is comparable to that of the ferroelectric material. However, its crystal symmetry does not allow it to be a ferroelectric material. Hence, the electrical properties have revived the considerable research interest on these materials, not only for academic interest, but also for technological applications. There are a few reports on temperature dependent dielectric behavior of these materials. However, the exact cause of dielectric as well as electrical conductivity is yet to be established. Hence, Al (very good conducting material) substituted barium hexaferrite (BaFe12-xAlxO19, x = 0.0-4.0) has been prepared by following the modified sol-gel method to understand the ac and DC electrical properties of these materials. The crystal structure and parameters have been studied by employing the XRD and FTIR techniques. There are two transition temperatures, which have been observed in the temperature dependent ac dielectric and DC resistivity measurement. The response of dielectric behaviors to temperature is similar to that of the ferroelectric material; however, the dielectric polarization is due to the polaron hopping, which is evident from the DC resistivity analysis. Hence, the present observations lead to understand the electrical properties of barium hexaferrite. The frequency dependent dielectric dispersion can be understood by the modified Debye model. More interestingly, the dielectric constant decreases and DC resistivity increases with the increase in the Al concentration, which has the correlation between bond length modifications in the crystal due to substitution.

  2. Titan Aerial Daughtercraft

    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...

  3. Titanic: A Statistical Exploration.

    Science.gov (United States)

    Takis, Sandra L.

    1999-01-01

    Uses the available data about the Titanic's passengers to interest students in exploring categorical data and the chi-square distribution. Describes activities incorporated into a statistics class and gives additional resources for collecting information about the Titanic. (ASK)

  4. Novel RF and microwave components employing ferroelectric and solid-state tunable capacitors for multi-functional wireless communication systems

    Science.gov (United States)

    Tombak, Ali

    The recent advancement in wireless communications demands an ever increasing improvement in the system performance and functionality with a reduced size and cost. This thesis demonstrates novel RF and microwave components based on ferroelectric and solid-state based tunable capacitor (varactor) technologies for the design of low-cost, small-size and multi-functional wireless communication systems. These include tunable lumped element VHF filters based on ferroelectric varactors, a beam-steering technique which, unlike conventional systems, does not require separate power divider and phase shifters, and a predistortion linearization technique that uses a varactor based tunable R-L-C resonator. Among various ferroelectric materials, Barium Strontium Titanate (BST) is actively being studied for the fabrication of high performance varactors at RF and microwave frequencies. BST based tunable capacitors are presented with typical tunabilities of 4.2:1 with the application of 5 to 10 V DC bias voltages and typical loss tangents in the range of 0.003--0.009 at VHF frequencies. Tunable lumped element lowpass and bandpass VHF filters based on BST varactors are also demonstrated with tunabilities of 40% and 57%, respectively. A new beam-steering technique is developed based on the extended resonance power dividing technique. Phased arrays based on this technique do not require separate power divider and phase shifters. Instead, the power division and phase shifting circuits are combined into a single circuit, which utilizes tunable capacitors. This results in a substantial reduction in the circuit complexity and cost. Phased arrays based on this technique can be employed in mobile multimedia services and automotive collision avoidance radars. A 2-GHz 4-antenna and a 10-GHz 8-antenna extended resonance phased arrays are demonstrated with scan ranges of 20 degrees and 18 degrees, respectively. A new predistortion linearization technique for the linearization of RF

  5. Aspiration of Barium Contrast

    Directory of Open Access Journals (Sweden)

    Cristina Fuentes Santos

    2014-01-01

    Full Text Available The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test.

  6. Observed Barium Emission Rates

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  7. Lower GI Series (Barium Enema)

    Science.gov (United States)

    ... uses x-rays and a chalky liquid called barium to view your large intestine . The barium will make your large intestine more visible on ... single-contrast lower GI series, which uses only barium a double-contrast or air-contrast lower GI ...

  8. Ferroelectric switching of elastin

    Science.gov (United States)

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  9. Ferroelectricity at the nanoscale basics and applications

    CERN Document Server

    Fridkin, Vladimir

    2014-01-01

    This book examines a wide range of ferroelectric materials. It explains the theoretical background of ultrathin ferroelectric films,  presents applications of ferroelectric materials, and displays the mechanism of switching of nanosized ferroelectric films.

  10. Organometal Halide Perovskite Solar Absorbers and Ferroelectric Nanocomposites for Harvesting Solar Energy

    Science.gov (United States)

    Hettiarachchi, Chaminda Lakmal

    Organometal halide perovskite absorbers such as methylammonium lead iodide chloride (CH3NH3PbI3-xClx), have emerged as an exciting new material family for photovoltaics due to its appealing features that include suitable direct bandgap with intense light absorbance, band gap tunability, ultra-fast charge carrier generation, slow electron-hole recombination rates, long electron and hole diffusion lengths, microsecond-long balanced carrier mobilities, and ambipolarity. The standard method of preparing CH3NH3PbI3-xClx perovskite precursors is a tedious process involving multiple synthesis steps and, the chemicals being used (hydroiodic acid and methylamine) are quite expensive. This work describes a novel, single-step, simple, and cost-effective solution approach to prepare CH3NH3PbI3-xClx thin films by the direct reaction of the commercially available CH3NH 3Cl (or MACl) and PbI2. A detailed analysis of the structural and optical properties of CH3NH3PbI3-xCl x thin films deposited by aerosol assisted chemical vapor deposition is presented. Optimum growth conditions have been identified. It is shown that the deposited thin films are highly crystalline with intense optical absorbance. Charge carrier separation of these thin films can be enhanced by establishing a local internal electric field that can reduce electron-hole recombination resulting in increased photo current. The intrinsic ferroelectricity in nanoparticles of Barium Titanate (BaTiO3 -BTO) embedded in the solar absorber can generate such an internal field. A hybrid structure of CH3NH 3PbI3-xClx perovskite and ferroelectric BTO nanocomposite FTO/TiO2/CH3NH3PbI3-xClx : BTO/P3HT/Cu as a new type of photovoltaic device is investigated. Aerosol assisted chemical vapor deposition process that is scalable to large-scale manufacturing was used for the growth of the multilayer structure. TiO 2 and P3HT with additives were used as ETL and HTL respectively. The growth process of the solar absorber layer includes the

  11. Multiparameter Sensor Chip with Barium Strontium Titanate as Multipurpose Material

    OpenAIRE

    Huck, Christina; Poghossian, Arshak; Kerroumi, Iman; Schusser, Sebastian; Backer, Matthias; Zander, Willi; Schubert, Juergen; Buniatyan, Vahe V; Martirosyan, Norayr W; Wagner, Patrick Hermann; Schoning, Michael J

    2014-01-01

    It is well known that biochemical and biotechnological processes are strongly dependent and affected by a variety of physico-chemical parameters such as pH value, temperature, pressure and electrolyte conductivity. Therefore, these quantities have to be monitored or controlled in order to guarantee a stable process operation, optimization and high yield. In this work, a sensor chip for the multiparameter detection of three physico-chemical parameters such as electrolyte conductivity, pH and t...

  12. Patterned solid state growth of barium titanate crystals

    Science.gov (United States)

    Ugorek, Michael Stephen

    An understanding of microstructure evolution in ceramic materials, including single crystal development and abnormal/enhanced grain growth should enable more controlled final ceramic element structures. In this study, two different approaches were used to control single crystal development in a patterned array. These two methods are: (1) patterned solid state growth in BaTiO 3 ceramics, and (2) metal-mediated single crystal growth in BaTiO 3. With the patterned solid state growth technique, optical photolithography was used to pattern dopants as well as [001] and [110] BaTiO3 single crystal template arrays with a 1000 microm line pattern array with 1000 microm spacings. These patterns were subsequently used to control the matrix grain growth evolution and single crystal development in BaTiO3. It was shown that the growth kinetics can be controlled by a small initial grain size, atmosphere conditions, and the introduction of a dopant at selective areas/interfaces. By using a PO2 of 1x10-5 atm during high temperature heat treatment, the matrix coarsening has been limited (to roughly 2 times the initial grain size), while retaining single crystal boundary motion up to 0.5 mm during growth for dwell times up to 9 h at 1300°C. The longitudinal and lateral growth rates were optimized at 10--15 microm/h at 1300°C in a PO2 of 1x10 -5 atm for single crystal growth with limited matrix coarsening. Using these conditions, a patterned microstructure in BaTiO3 was obtained. With the metal-mediated single crystal growth technique, a novel approach for fabricating 2-2 single crystal/polymer composites with a kerf texture development were studied using both [001] and [110] BaTiO3 single crystals templates. By using a PO 2 of 1x10-11 atm during high temperature heat treatment, matrix coarsening was limited while enabling single crystal boundary motion up to 0.35 mm during growth between 1250°C and 1300°C with growth rates ˜ 3--4 microm/h for both single crystal orientations. By removing the inner electrodes, 2-2 single crystal (or ceramic) composites were prepared. The piezoelectric and dielectric properties of the composites of the two compositions were measured. The d33 and d31 of the composites were similar to the polycrystalline ceramic of the same composition.

  13. Magnetoelectric effect in cobalt ferrite–barium titanate composites ...

    Indian Academy of Sciences (India)

    relaxation process and resistivity of the materials. However, the conductivity behavior in. CoFe2O4–BaTiO3 composites has not been studied. In this paper we report the dc electrical conductivity and thermoelectric power (TEP) as a function of temperature for this system. Dielectric behavior is also studied to understand the ...

  14. Positron annihilation in calcium-doped barium titanate

    International Nuclear Information System (INIS)

    Li, L.T.; Zhang, X.W.; Smyth, D.M.

    1987-01-01

    The Positron Annihilation Technique (PAT) has been used to study lattice defects in CaO-doped BaTiO/sub 3/ having the general composition BaTi/sub 1-x/Ca/sub x/O/sub 3-x/, with x = 0, 0.005, 0.010, 0.015, and 0.020. The long lifetime, tau/sub 2/, and the mean lifetime, tau/sub m/, of the positrons were both found to increase with increasing Ca content, x, up to x = 0.015-0.020. This is in good agreement wit the solubility limit for Ca on Ti-sites in BaTiO/sub 3/ found by others from measurements of the equilibrium electrical conductivity, and by other investigators from x-ray diffraction studies. In these studies, it was shown that for compositions with (Ba+Ca)/Ti > 1, Ca can be forced to occupy Ti-sites up to 1.5-2%, where it acts as a doubly-charged acceptor center that is compensated by oxygen vacancies. It is suggested that the oxygen vacancies represent places where the annihilation of positrons is delayed because of the low local electron density. These results indicate that the PAT can be a useful tool for the characterization of the defect structure of complex oxides

  15. Efficient photoemission from robust ferroelectric ceramics

    International Nuclear Information System (INIS)

    Boscolo, I.; Castellano, M.; Catani, L.; Ferrario, M.; Tazzioli, F.; Giannessi, L.

    1999-01-01

    Experimental results on photoemission by ferroelectric ceramic disks, with a possible interpretation, are present. Two types of lead zirconate titanate lanthanum doped, PLZT, ceramics have been used for tests. 25 ps light pulses of 532 and 355 nm were used for excitation. The intensity ranged within the interval 0.1-3 GW/cm 2. The upper limit of the intensity was established by the damage threshold tested by the onset of ion emission. At low value of the intensity the yield was comparable at the two wavelengths. At the highest intensity of green light the emitted charge was 1 nC per 10 mm 2, but it was limited by the space charge effect. In fact, the applied field was only 20 kV/cm, allowed both by the mechanical design of the apparatus and the poor vacuum, 10 - 4 mbar. No surface processing was required. The measurement of the electron pulse length under way

  16. Isotopic exchange reaction between barium ion and tri barium phosphate

    International Nuclear Information System (INIS)

    Bilgin, G.B.; Cetin, I.

    1982-01-01

    Heterogeneous exchange reaction of tri barium phosphate in barium chloride solution has been studied using 133 Ba as a tracer. The results show that the exchange fraction increases as barium chloride concentration increases for different mole ratio of the exchange ion on the solid surface and in the solution. The phenomenon was studied with respect to the previous treatment of the precipitate leading to different crystal sizes and the effect of reaction time. (author)

  17. Lithium in the barium stars

    International Nuclear Information System (INIS)

    Pinsonneault, M.H.; Sneden, C.

    1984-01-01

    New high-resolution spectra of the lithium resonance doublet have provided lithium abundances or upper limits for 26 classical and mild barium stars. The lithium lines always are present in the classical barium stars. Lithium abundances in these stars obey a trend with stellar masses consistent with that previously derived for ordinary K giants. This supports the notion that classical barium stars are post-core-He-flash or core-He-burning stars. Lithium contents in the mild barium stars, however, often are much smaller than those of the classical barium stars sometimes only upper limits may be determined. The cause for this difference is not easily understood, but may be related to more extensive mass loss by the mild barium stars. 45 references

  18. Mechanisms of aging and fatigue in ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Genenko, Yuri A. [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany); Glaum, Julia [Department of Materials Science and Engineering, University of New South Wales, Sydney (Australia); Hoffmann, Michael J. [Institut für keramische Werkstoffe, Haid-und-Neu Str. 7, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Albe, Karsten, E-mail: albe@mm.tu-darmstadt.de [Sonderforschungsbereich 595, Institut für Materialwissenschaft, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt (Germany)

    2015-02-15

    Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr{sub 1−x}Ti{sub x}]O{sub 3} (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi{sub 1/2}Na{sub 1/2}TiO{sub 3} (BNT) and alkali niobate [K{sub x}Na{sub 1−x}]NbO{sub 3} (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies.

  19. Mechanisms of aging and fatigue in ferroelectrics

    International Nuclear Information System (INIS)

    Genenko, Yuri A.; Glaum, Julia; Hoffmann, Michael J.; Albe, Karsten

    2015-01-01

    Highlights: • Experiments on aging and fatigue of bulk ferroelectrics are thoroughly reviewed. • Lead-based PZT and lead-free BNT–BT and KNN materials are covered. • Various fatigue regimes and factors are classified. • Defect associate formation and alignment are analyzed by density functional theory. • Emerging of internal bias field is studied within drift-diffusion approach. - Abstract: A comprehensive review of aging and fatigue phenomena in bulk polycrystalline ferroelectrics is presented. Three material classes are covered, namely the most widely used Pb[Zr 1−x Ti x ]O 3 (PZT) ceramics and lead-free materials, including those based on bismuth sodium titanate Bi 1/2 Na 1/2 TiO 3 (BNT) and alkali niobate [K x Na 1−x ]NbO 3 (KNN). Aging is studied in poled and unpoled states both experimentally and theoretically. The variety of different loading regimes for fatigue includes DC electric field, unipolar, sesquipolar and bipolar cycling and all these differently combined with mechanical loading at different frequencies and temperatures. The role of device geometries and electrode materials is addressed and models describing charge migration and defect dipole re-orientation are discussed in the context of recent experimental studies

  20. A finite element model of ferroelectric/ferroelastic polycrystals

    Energy Technology Data Exchange (ETDEWEB)

    HWANG,STEPHEN C.; MCMEEKING,ROBERT M.

    2000-02-17

    A finite element model of polarization switching in a polycrystalline ferroelectric/ferroelastic ceramic is developed. It is assumed that a crystallite switches if the reduction in potential energy of the polycrystal exceeds a critical energy barrier per unit volume of switching material. Each crystallite is represented by a finite element with the possible dipole directions assigned randomly subject to crystallographic constraints. The model accounts for both electric field induced (i.e. ferroelectric) switching and stress induced (i.e. ferroelastic) switching with piezoelectric interactions. Experimentally measured elastic, dielectric, and piezoelectric constants are used consistently, but different effective critical energy barriers are selected phenomenologically. Electric displacement versus electric field, strain versus electric field, stress versus strain, and stress versus electric displacement loops of a ceramic lead lanthanum zirconate titanate (PLZT) are modeled well below the Curie temperature.

  1. Phenomenological theory of size effects in ultrafine ferroelectric particles (PbTiO3-type)

    International Nuclear Information System (INIS)

    Jiang, B.; Bursill, L.A.

    1998-01-01

    A new phenomenological model is proposed and discussed to study the size effects on phase transitions in PbTiO 3 -type ferroelectric particles. This model, by taking size effects on the phenomenological Landau-Ginzburg-Devonshire coefficients into consideration, can successfully explain the size effects on Curie temperature, c/a ratio, thermal and dielectric properties of lead-titanate-type ferroelectric particles. Theoretical and experimental results for PbTiO 3 fine particles are also compared and discussed. The relationship between the current model and the model of Zhong et al (Phys. Rev. B 50, 698 (1994)) is also presented. (authors)

  2. Barium and radium radiopolarography

    International Nuclear Information System (INIS)

    Fourest, B.

    1979-01-01

    Radiopolarography has been applied to the study of two elements (barium and radium) which is difficult by classical polarography because of their strong electropositivity. Various parameters have been considered: nature, concentration and pH of supporting electrolyte. In any case of investigated mediums, the reduction to the metallic state reaction appeared to be reversible. An important variation of the barium half-wave potential E 1/2 with the ionic strength μ of the solution, imposed by LiCl used as supporting electrolyte, has been observed. It gives the possibility to estimate, for μ = 0, E 1/2 (Ba) = - 1.916 V/S.C.E. and E 1/2(Ra) = - 1.852 V/S.C.E. The values of barium and radium half wave potentials, obtained with a good accuracy in LiCl (or LiClO 4 ) 0.1 M medium, have been used to establish the amalgamation energy Δ 2 (M) of these elements. A linear variation of Δ 2 (M) with the metallic radius of the 2a elements has been obtained. On the other hand, by making the concentration of the complex forming agent (Cit 3- ) vary in the solution, we have a shift in the half wave potential from which we can deduce the stability constant of the complexe and its composition (BaCit - ; pK 1 =2). At last, nature and concentration of the supporting electrolyte (between 5.10 -2 M and 5M) have a determining influence on the extent of the polarogram plateau. This plateau is limited by an 'hollow effect' preceding the supporting electrolyte discharge. An interpretation of this effect is suggested which is based on the Stern model [fr

  3. Stacking effect on the ferroelectric properties of PZT/PLZT multilayer thin films formed by photochemical metal-organic deposition

    International Nuclear Information System (INIS)

    Park, Hyeong-Ho; Park, Hyung-Ho; Hill, Ross H.

    2004-01-01

    The ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-doped lead zirconate titanate (PLZT) multilayer films formed by photochemical metal-organic deposition (PMOD) using photosensitive precursors have been characterized. The substitution of La for Pb was reported to induce improved ferroelectric properties, especially fatigue resistance, through the reduction of oxygen vacancies. The relation between La-substitution and the ferroelectric properties was investigated by characterization of the effect of the order of stacking four ferroelectric layers of PZT or PLZT in the multilayer films 4-PZT, PZT/2-PLZT/PZT, PLZT/2-PZT/PLZT, and 4-PLZT. The films with the PLZT layer at the top and bottom showed an improvement in the fatigue resistance. It was revealed that defect dipole such as O vacancy was reduced at the ferroelectric/Pt interface by doping with La. Also, the bottom layer, just on Pt substrate had a significant influence on the surface microstructure and growth orientation of ferroelectric film

  4. Barium uranyl diphosphonates

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Anna-Gay D., E-mail: nelsoa@umich.edu [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Alekseev, Evgeny V. [Institute of Energy and Climate Research (IEK-6), Forschungszentrum Juelich Wilhelm-Johnen-Strasse, Juelich 52428 (Germany); Ewing, Rodney C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109-1005 (United States); Albrecht-Schmitt, Thomas E. [Department of Civil Engineering and Geological Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2012-08-15

    Three Ba{sup 2+}/UO{sub 2}{sup 2+} methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 Degree-Sign C. These compounds, Ba[UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{center_dot}1.4H{sub 2}O (Ba-1), Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2}F{sub 6}]{center_dot}6H{sub 2}O (Ba-2), and Ba{sub 2}[(UO{sub 2}){sub 2}(CH{sub 2}(PO{sub 3}){sub 2})F{sub 4}]{center_dot}5.75H{sub 2}O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO{sub 5}F{sub 2} pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{sup 2-} sheets. The interlayer space of the structures is occupied by Ba{sup 2+}, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance. - Graphical abstract: Illustration of the stacking of the layers in Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2})F{sub 6}]{center_dot}6H{sub 2}O viewed along the c-axis. The structure is constructed from UO{sub 7} pentagonal bipyramidal units, U(1)O{sub 7}=gray, U(2)O{sub 7}=yellow, barium=blue, phosphorus=magenta, fluorine=green, oxygen=red, carbon=black, and hydrogen=light peach. Highlights: Black-Right-Pointing-Pointer The polymerization of the UO{sub 2}{sup 2+} sites to form uranyl dimers leads to structural variations in compounds. Black-Right-Pointing-Pointer Barium cations stitch uranyl diphosphonate anionic layers together, and help mediate structure formation. Black-Right-Pointing-Pointer HF acts as both a

  5. Barium toxicosis in a dog.

    Science.gov (United States)

    Adam, Fiona H; Noble, Peter J M; Swift, Simon T; Higgins, Brent M; Sieniawska, Christine E

    2010-09-01

    A 2-year-old 14.9-kg (32.8-lb) neutered female Shetland Sheepdog was admitted to the University of Liverpool Small Animal Teaching Hospital for evaluation of acute collapse. At admission, the dog was tachypneic and had reduced limb reflexes and muscle tone in all limbs consistent with diffuse lower motor neuron dysfunction. The dog was severely hypokalemic (1.7 mEq/L; reference range, 3.5 to 5.8 mEq/L). Clinical status of the dog deteriorated; there was muscle twitching, flaccid paralysis, and respiratory failure, which was considered a result of respiratory muscle weakness. Ventricular arrhythmias and severe acidemia (pH, 7.18; reference range, 7.35 to 7.45) developed. Intoxication was suspected, and plasma and urine samples submitted for barium analysis had barium concentrations comparable with those reported in humans with barium toxicosis. Analysis of barium concentrations in 5 control dogs supported the diagnosis of barium toxicosis in the dog. Fluids and potassium supplementation were administered IV. The dog recovered rapidly. Electrolyte concentrations measured after recovery were consistently unremarkable. Quantification of plasma barium concentration 56 days after the presumed episode of intoxication revealed a large decrease; however, the plasma barium concentration remained elevated, compared with that in control dogs. To our knowledge, this case represented the first description of barium toxicosis in the veterinary literature. Barium toxicosis can cause life-threatening hypokalemia; however, prompt supportive treatment can yield excellent outcomes. Barium toxicosis is a rare but important differential diagnosis in animals with hypokalemia and appropriate clinical signs.

  6. What makes the difference in perovskite titanates?

    Science.gov (United States)

    Bussmann-Holder, Annette; Roleder, Krystian; Ko, Jae-Hyeon

    2018-06-01

    We have investigated in detail the lattice dynamics of five different perovskite titanates ATiO3 (A = Ca, Sr, Ba, Pb, Eu) where the A sites are occupied by +2 ions. In spite of the largely ionic character of these ions, the properties of these compounds differ substantially. They range from order/disorder like, to displacive ferroelectric, quantum paraelectric, and antiferromagnetic. All compounds crystallize in the cubic structure at high temperature and undergo structural phase transitions to tetragonal symmetry, partly followed by further transitions to lower symmetries. Since the TiO6 moiety is the essential electronic and structural unit, the question arises, what makes the significant difference between them. It is shown that the lattice dynamics of these compounds are very different, and that mode-mode coupling effects give rise to many distinct properties. In addition, the oxygen ion nonlinear polarizability plays a key role since it dominates the anharmonicity of these perovskites and determines the structural instability.

  7. Optical properties of calcium barium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Heine, Urs; Betzler, Klaus [Department of Physics, University of Osnabrueck (Germany); Burianek, Manfred; Muehlberg, Manfred [Institute of Crystallography, University of Cologne (Germany)

    2010-07-01

    We report on optical measurements on the novel tungsten bronze type calcium barium niobate. [001]-oriented transparent and colorless single crystals were grown by the Czochralski method with dimensions of 12 mm in diameter and about 80 mm in length. With its relatively high Curie temperature of about 538 K for the congruently melting composition of 28.1 mole% calcium and its high nonlinear coefficients, CBN is a promising material for future applications. Recent experiments revealed, that the application of an external electric field of several kV/cm to CBN at room temperature leads to an increasing opacity of the sample. This might be a drawback considering the future usability of CBN in optical systems. We present investigations on the transmittance behaviour of CBN under external electric fields, demonstrating the erasement of the clouding without affecting the polarization. Experiments have been performed at temperatures ranging from room temperature to approximately 480 K. When heating up the sample, its colorless appearance changes to a light yellow, which can be attributed to a shift of the band edge to longer wavelengths with increasing temperature. To further investigate the transmittance properties of CBN, measurements of the band edge under various temperatures up to the ferroelectric phase transition have been performed.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 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 2 -MCl systems.

  9. Barium diffusion in metallo-organic solution deposited barrier layers and Y1Ba2Cu3O7-x films

    International Nuclear Information System (INIS)

    Lipeles, R.A.; Leung, M.S.; Thiede, D.A.

    1990-01-01

    This paper reports on barium silicate and barium aluminate films that were studied for use as chemical reaction and diffusion barrier layers for Y 1 Ba 2 Cu 3 O 7-x (YBC) deposited on sapphire and fused silica substrates by the sol-gel technique. Depth profiling by secondary ion mass spectrometry (SIMS) was used to characterize the abruptness of the interfaces between the barrier layer and the YBC film as well as the barrier layer and the substrate. The authors found that barium aluminate films reacted with fused silica substrates forming a coarse-grained barium silicate phase. Barium silicate, BaSiO 3 , also reacted with silica substrates forming a broad, amorphous reaction zone containing some BaSi 2 O 5 . Although barium silicate and barium aluminate deposited on sapphire formed a BaAl 12 O 19 phase, they provided a barrier to barium diffusion from sol-gel deposited YBC. Crystalline barium aluminate grown on c-cut sapphire was the most effective barrier layer for the growth of YBC films; compositionally uniform YBC films were made similar to that grown on strontium titanate substrates. These data show that chemically stable, crystalline films are more effective barrier layers than amorphous films

  10. 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.

  11. 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

  12. Ferroelectric Negative Capacitance Domain Dynamics

    OpenAIRE

    Hoffmann, Michael; Khan, Asif Islam; Serrao, Claudy; Lu, Zhongyuan; Salahuddin, Sayeef; Pešić, Milan; Slesazeck, Stefan; Schroeder, Uwe; Mikolajick, Thomas

    2017-01-01

    Transient negative capacitance effects in epitaxial ferroelectric Pb(Zr$_{0.2}$Ti$_{0.8}$)O$_3$ capacitors are investigated with a focus on the dynamical switching behavior governed by domain nucleation and growth. Voltage pulses are applied to a series connection of the ferroelectric capacitor and a resistor to directly measure the ferroelectric negative capacitance during switching. A time-dependent Ginzburg-Landau approach is used to investigate the underlying domain dynamics. The transien...

  13. Ferroelectric materials and their applications

    CERN Document Server

    Xu, Y

    2013-01-01

    This book presents the basic physical properties, structure, fabrication methods and applications of ferroelectric materials. These are widely used in various devices, such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage, display devices, etc. The ferroelectric materials described in this book include a relatively complete list of practical and promising ferroelectric single crystals, bulk ceramics and thin films. Included are perovskite-type, lithium niobate, tungsten-bronze-type, water-soluable

  14. Titan Casts Revealing Shadow

    Science.gov (United States)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  15. Raising the Titanic.

    Science.gov (United States)

    Baker, Romona

    1990-01-01

    Described is an activity in which groups of students investigate engineering principles by writing a feasibility study to raise the luxury liner, Titanic. The problem statement and directions, and suggestions for problem solutions are included. (CW)

  16. Barium aluminate cement: its application

    International Nuclear Information System (INIS)

    Drozdz, M.; Wolek, W.

    1975-01-01

    The technology of manufacturing barium aluminate cement from barium sulfate and alumina, using a rotary kiln for firing the clinker is described. The method of granulation of the homogenized charge was used. Conditions of using the ''to mud'' method in industry were indicated. The physical and chemical properties of barium aluminate cement are determined and the quality of several batches of cement prepared on a semi-industrial scale and their suitability for making highly refractory concretes are tested. The optimal composition of the concretes is determined as a function of the mixing water and barium aluminate cement contents. Several experimental batches of concretes were used in the linings of furnaces in the steel industry. The suitability of these cements for use in fields other than steelmaking is examined. It is established that calcium aluminate cement has certain limited applications [fr

  17. 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,"…

  18. Titan's Ammonia Feature

    Science.gov (United States)

    Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

    2011-01-01

    NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

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

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. Statistical properties of barium stars

    International Nuclear Information System (INIS)

    Hakkila, J.E.

    1986-01-01

    Barium stars are G- and K-giant stars with atmospheric excesses of s-process elements, and a broadband spectral depression in the blue portion of the spectrum. The strength of the λ4554 Ball line is used as a classification parameter known as the Barium Intensity. They have a mean absolute magnitude of 1.0 and a dispersion of 1.2 magnitudes (assuming a Gaussian distribution in absolute magnitude) as measured from secular and statistical parallaxes. These stars apparently belong to a young-disk population from analyses of both the solar reflex motion and their residual velocity distribution, which implies that they have an upper mass limit of around three solar masses. There is no apparent correlation of barium intensity with either luminosity or kinematic properties. The barium stars appear to be preferentially distributed in the direction of the local spiral arm, but show no preference to associate with or avoid the direction of the galactic center. They do not appear related to either the carbon or S-stars because of these tendencies and because of the stellar population to which each type of star belongs. The distribution in absolute magnitude combined with star count analyses implies that these stars are slightly less numerous than previously believed. Barium stars show infrared excesses that correlate with their barium intensities

  2. Barium light source method and apparatus

    Science.gov (United States)

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

    2002-01-01

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

  3. Ferroelectricity the fundamentals collection

    CERN Document Server

    Jimenez, Basilio

    2008-01-01

    This indispensable collection of seminal papers on ferroelectricity provides an overview over almost a hundred years of basic and applied research. Containing historic contributions from renowned authors, this book presents developments in an area of science that is still rapidly growing. Although primarily aimed at scientists and academics involved in research, this will also be of use to students as well as newcomers to the field.

  4. Electric field cycling behavior of ferroelectric hafnium oxide.

    Science.gov (United States)

    Schenk, Tony; Schroeder, Uwe; Pešić, Milan; Popovici, Mihaela; Pershin, Yuriy V; Mikolajick, Thomas

    2014-11-26

    HfO2 based ferroelectrics are lead-free, simple binary oxides with nonperovskite structure and low permittivity. They just recently started attracting attention of theoretical groups in the fields of ferroelectric memories and electrostatic supercapacitors. A modified approach of harmonic analysis is introduced for temperature-dependent studies of the field cycling behavior and the underlying defect mechanisms. Activation energies for wake-up and fatigue are extracted. Notably, all values are about 100 meV, which is 1 order of magnitude lower than for conventional ferroelectrics like lead zirconate titanate (PZT). This difference is mainly atttributed to the one to two orders of magnitude higher electric fields used for cycling and to the different surface to volume ratios between the 10 nm thin films in this study and the bulk samples of former measurements or simulations. Moreover, a new, analog-like split-up effect of switching peaks by field cycling is discovered and is explained by a network model based on memcapacitive behavior as a result of defect redistribution.

  5. Electric and ferroelectric properties of PZT/BLT multilayer films prepared by photochemical metal-organic deposition

    Science.gov (United States)

    Park, Hyeong-Ho; Lee, Hong-Sub; Park, Hyung-Ho; Hill, Ross H.; Hwang, Yun Taek

    2009-01-01

    The electric and ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-substituted bismuth titanate (BLT) multilayer films prepared using photosensitive precursors were characterized. The electric and ferroelectric properties were investigated by studying the effect of the stacking order of four ferroelectric layers of PZT or BLT in 4-PZT, PZT/2-BLT/PZT, BLT/2-PZT/BLT, and 4-BLT multilayer films. The remnant polarization values of the 4-BLT and BLT/2-PZT/BLT multilayer films were 12 and 17 μC/cm 2, respectively. Improved ferroelectric properties of the PZT/BLT multilayer films were obtained by using a PZT intermediate layer. The films which contained a BLT layer on the Pt substrate had improved leakage currents of approximately two orders of magnitude and enhanced fatigue resistances compared to the films with a PZT layer on the Pt substrate. These improvements are due to the reduced number of defects and space charges near the Pt electrodes. The PZT/BLT multilayer films prepared by photochemical metal-organic deposition (PMOD) possessed enhanced electric and ferroelectric properties, and allow direct patterning to fabricate micro-patterned systems without dry etching.

  6. Electric and ferroelectric properties of PZT/BLT multilayer films prepared by photochemical metal-organic deposition

    International Nuclear Information System (INIS)

    Park, Hyeong-Ho; Lee, Hong-Sub; Park, Hyung-Ho; Hill, Ross H.; Hwang, Yun Taek

    2009-01-01

    The electric and ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-substituted bismuth titanate (BLT) multilayer films prepared using photosensitive precursors were characterized. The electric and ferroelectric properties were investigated by studying the effect of the stacking order of four ferroelectric layers of PZT or BLT in 4-PZT, PZT/2-BLT/PZT, BLT/2-PZT/BLT, and 4-BLT multilayer films. The remnant polarization values of the 4-BLT and BLT/2-PZT/BLT multilayer films were 12 and 17 μC/cm 2 , respectively. Improved ferroelectric properties of the PZT/BLT multilayer films were obtained by using a PZT intermediate layer. The films which contained a BLT layer on the Pt substrate had improved leakage currents of approximately two orders of magnitude and enhanced fatigue resistances compared to the films with a PZT layer on the Pt substrate. These improvements are due to the reduced number of defects and space charges near the Pt electrodes. The PZT/BLT multilayer films prepared by photochemical metal-organic deposition (PMOD) possessed enhanced electric and ferroelectric properties, and allow direct patterning to fabricate micro-patterned systems without dry etching.

  7. Barium and iron abundances in red giants

    International Nuclear Information System (INIS)

    Fernandez-Villacanas, J.L.; Rego, M.; Cornide, M.

    1990-01-01

    An intermediate-dispersion abundance analysis has been carried out on a sample of 21 barium and 14 comparison stars. The excess of barium over iron has been used as the most representative indicator of peculiarity. These excesses are higher in the peculiar stars than in the nonpeculiar stars. Particularly interesting is the case of HD 67447, included in the comparison stars, with an excess Ba/Fe abundance = 1.61, probably a new barium star. A trend indicating a possible anticorrelation between barium overabundance and metallicity favors the suggestion that the barium strong group is older than the barium weak one. 36 refs

  8. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  9. Novel Photovoltaic Devices Using Ferroelectric Material and Colloidal Quantum Dots

    Science.gov (United States)

    Paik, Young Hun

    As the global concern for the financial and environmental costs of traditional energy resources increases, research on renewable energy, most notably solar energy, has taken center stage. Many alternative photovoltaic (PV) technologies for 'the next generation solar cell' have been extensively studied to overcome the Shockley-Queisser 31% efficiency limit as well as tackle the efficiency vs. cost issues. This dissertation focuses on the novel photovoltaic mechanism for the next generation solar cells using two inorganic nanomaterials, nanocrystal quantum dots and ferroelectric nanoparticles. Lead zirconate titanate (PZT) materials are widely studied and easy to synthesize using solution based chemistry. One of the fascinating properties of the PZT material is a Bulk Photovoltaic effect (BPVE). This property has been spotlighted because it can produce very high open circuit voltage regardless of the electrical bandgap of the materials. However, the poor optical absorption of the PZT materials and the required high temperature to form the ferroelectric crystalline structure have been obstacles to fabricate efficient photovoltaic devices. Colloidal quantum dots also have fascinating optical and electrical properties such as tailored absorption spectrum, capability of the bandgap engineering due to the wide range of material selection and quantum confinement, and very efficient carrier dynamics called multiple exciton generations. In order to utilize these properties, many researchers have put numerous efforts in colloidal quantum dot photovoltaic research and there has been remarkable progress in the past decade. However, several drawbacks are still remaining to achieve highly efficient photovoltaic device. Traps created on the large surface area, low carrier mobility, and lower open circuit voltage while increasing the absorption of the solar spectrum is main issues of the nanocrystal based photovoltaic effect. To address these issues and to take the advantages of

  10. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  11. Titan Orbiter Aerorover Mission

    Science.gov (United States)

    Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

    2001-01-01

    We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

  12. Non-Resonant Magnetoelectric Energy Harvesting Utilizing Phase Transformation in Relaxor Ferroelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Peter Finkel

    2015-12-01

    Full Text Available Recent advances in phase transition transduction enabled the design of a non-resonant broadband mechanical energy harvester that is capable of delivering an energy density per cycle up to two orders of magnitude larger than resonant cantilever piezoelectric type generators. This was achieved in a [011] oriented and poled domain engineered relaxor ferroelectric single crystal, mechanically biased to a state just below the ferroelectric rhombohedral (FR-ferroelectric orthorhombic (FO phase transformation. Therefore, a small variation in an input parameter, e.g., electrical, mechanical, or thermal will generate a large output due to the significant polarization change associated with the transition. This idea was extended in the present work to design a non-resonant, multi-domain magnetoelectric composite hybrid harvester comprised of highly magnetostrictive alloy, [Fe81.4Ga18.6 (Galfenol or TbxDy1-xFe2 (Terfenol-D], and lead indium niobate–lead magnesium niobate–lead titanate (PIN-PMN-PT domain engineered relaxor ferroelectric single crystal. A small magnetic field applied to the coupled device causes the magnetostrictive element to expand, and the resulting stress forces the phase change in the relaxor ferroelectric single crystal. We have demonstrated high energy conversion in this magnetoelectric device by triggering the FR-FO transition in the single crystal by a small ac magnetic field in a broad frequency range that is important for multi-domain hybrid energy harvesting devices.

  13. 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.

  14. Diurnal variations of Titan

    Science.gov (United States)

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

    2009-04-01

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

  15. Effect of working pressure and annealing temperature on ...

    Indian Academy of Sciences (India)

    roughness was found at higher temperatures as a result of a more heterogeneous growth and less tensions. Keywords. Barium strontium titanate; thin film; pulsed laser deposition; ferroelectric. 1. Introduction. Perovskite barium strontium titanate (BST) thin films are promising candidates for dynamic random access memory.

  16. Visualization of dielectric constant-electric field-temperature phase maps for imprinted relaxor ferroelectric thin films

    International Nuclear Information System (INIS)

    Frederick, J. C.; Kim, T. H.; Maeng, W.; Brewer, A. A.; Podkaminer, J. P.; Saenrang, W.; Vaithyanathan, V.; Schlom, D. G.; Li, F.; Chen, L.-Q.; Trolier-McKinstry, S.; Rzchowski, M. S.; Eom, C. B.

    2016-01-01

    The dielectric phase transition behavior of imprinted lead magnesium niobate–lead titanate relaxor ferroelectric thin films was mapped as a function of temperature and dc bias. To compensate for the presence of internal fields, an external electric bias was applied while measuring dielectric responses. The constructed three-dimensional dielectric maps provide insight into the dielectric behaviors of relaxor ferroelectric films as well as the temperature stability of the imprint. The transition temperature and diffuseness of the dielectric response correlate with crystallographic disorder resulting from strain and defects in the films grown on strontium titanate and silicon substrates; the latter was shown to induce a greater degree of disorder in the film as well as a dielectric response lower in magnitude and more diffuse in nature over the same temperature region. Strong and stable imprint was exhibited in both films and can be utilized to enhance the operational stability of piezoelectric devices through domain self-poling.

  17. Study of the rheological properties of casting slips obtained from titanium oxide and bariun titanate in order to obtain pieces by means of casting in plaster moulds

    International Nuclear Information System (INIS)

    Amarante Junior, A.

    1986-01-01

    The behaviour of titanium-oxide (TiO 2 ) and barium titanate used in slip casting with plaster moulds is studied. Some data in several tests, as well as materials and methods applied are presented. (M.J.C.) [pt

  18. Effects on Ferroelectric Thin-Film Stacks and Devices for Piezoelectric MEMS Applications at Varied Total Ionizing Dose (TID)

    Science.gov (United States)

    2017-03-01

    non -linearly mobile internal interfaces, e.g. domain walls and eventual phase boundaries. Radiation exposure is expected...zirconate titanate; PZT; actuator; radiation ; gamma; total ionization dose; TID; top electrode; Pt; IrO2; polarization; PE; hysteresis; permittivity...Hayashigawa, et. al., “A 2 Mbit Radiation Hardened Stackable Ferroelectric Memory” Non - Volatile Memory Technology Symposium, NVMTS 07, Nov 10-13, 2007 Albuquerque, NM, USA

  19. Titan's icy scar

    Science.gov (United States)

    Griffith, C. A.; Penteado, P. F.; Turner, J. D.; Neish, C. D.; Mitri, G.; Montiel, M. J.; Schoenfeld, A.; Lopes, R. M. C.

    2017-09-01

    We conduct a Principal Components Analysis (PCA) of Cassini/VIMS [1] infrared spectral windows to identify and quantify weak surface features, with no assumptions on the haze and surface characteris- tics. This study maps the organic sediments, supplied by past atmospheres, as well as ice-rich regions that constitute Titan's bedrock.

  20. Patient dose variation investigated in four Irish hospitals for barium meal and barium enema examinations

    International Nuclear Information System (INIS)

    Carroll, E.; Brennan, P.C.

    2001-01-01

    Four hospitals have been studied, intra- and inter-hospital variations examined and the mean DAP values recorded for barium enemas and barium meals. Mean DAP values for barium meals and barium enemas at 11.4 Gy.cm 2 and 20.1 Gy.cm 2 respectively have been shown. Differences between individual examinations for barium meals varied by up to a factor of 185 and for barium enemas, up to a factor of 19, with hospital means for barium meal and enema examinations each differing by up to a factor of 3. The data provided by this study have suggested that large variations in patient dose do exist in Ireland for barium meal and barium enema examinations. Fluoroscopy time was shown to be a major contributor to the variations reported, with number of images playing a minor role. Results have demonstrated the need for standardisation of technique throughout the country for these examinations. (author)

  1. Ferroelectric capacitor with reduced imprint

    Science.gov (United States)

    Evans, Jr., Joseph T.; Warren, William L.; Tuttle, Bruce A.; Dimos, Duane B.; Pike, Gordon E.

    1997-01-01

    An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

  2. Electric-field influence on the neutron diffuse scattering near the ferroelectric transition of Sr.sub.0.61./sub.Ba.sub.0.39./sub.Nb.sub.2./sub.O.sub.6./sub.

    Czech Academy of Sciences Publication Activity Database

    Ondrejkovič, Petr; Kempa, Martin; Savinov, Maxim; Bednyakov, Petr; Kulda, J.; Bourges, P.; Dec, J.; Hlinka, Jiří

    2016-01-01

    Roč. 89, 7-8 (2016), s. 808-815 ISSN 0141-1594 R&D Projects: GA ČR GA16-09142S Institutional support: RVO:68378271 Keywords : relaxor ferroelectrics * lead-free * strontium barium niobate * neutron scattering * dielectric spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.060, year: 2016

  3. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  4. Temperature dependence of high field electromechanical coupling in ferroelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P M; Cain, M G; Stewart, M, E-mail: paul.weaver@npl.co.u [National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW (United Kingdom)

    2010-04-28

    A study of the temperature dependence of the electromechanical response of ferroelectric lead zirconate titanate (PZT) ceramics at high electric fields (up to 1.3 kV mm{sup -1}) is reported. Simultaneous measurements were performed of strain, electric field and polarization to form a complete response map from room temperature up to 200 {sup 0}C. An electrostrictive model is shown to provide an accurate description of the electromechanical response to high levels of induced polarization and electric field. This provides a method for decoupling strain contributions from thermal expansion and polarization changes. Direct measurements of electrostriction and thermal expansion, above and below the Curie temperature, are reported. Electrostriction coefficients are shown to be temperature dependent in these ceramic materials, with different values above and below the Curie temperature.

  5. Switching kinetics of a relaxor ferroelectric Sr0.75Ba0.25Nb2O6 observed by the second harmonic generation method

    International Nuclear Information System (INIS)

    Volk, Tatyana; Isakov, Dmitry; Belsley, Michael Scott; Ivleva, Lyudmila

    2009-01-01

    In this work we present a study of the ferroelectric switching kinetic process in strontium-barium niobate (SBN). The kinetics of polarization deduced from the dynamics of the diffuse second harmonic generation is in good qualitative agreement with thekinetics observed by more traditional polarization methods. Our work highlights the specific characteristics of polarization reversal in SBN, which is fundamentally different from that which occurs in model ferroelectrics. The presented optical measurements of the polarization processes provide several experimental advantages over traditional electrical measurements. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Fast ferroelectric phase shifters for energy recovery linacs

    Directory of Open Access Journals (Sweden)

    S. Yu Kazakov

    2010-11-01

    Full Text Available Fast phase shifters are described that use a novel barium strontium titanate ceramic that can rapidly change its dielectric constant as an external bias voltage is changed. These phase shifters promise to reduce by ∼10 times the power requirements for the rf source needed to drive an energy recovery linac (ERL. Such phase shifters will be coupled with superconducting radiofrequency cavities so as to tune them to compensate for phase instabilities, whether beam-driven or those caused by microphonics. The most promising design is presented, which was successfully cold tested and demonstrated a switching speed of ∼30  ns for 77 deg, corresponding to <0.5  ns per deg of rf phase. Other crucial issues (losses, phase shift values, etc. are discussed.

  7. Titanic exploration with GIS

    Science.gov (United States)

    Kerski, J.J.

    2004-01-01

    To help teachers and students investigate one of the world's most famous historical events using the geographic perspective and GIS tools and methods, the U.S. Geological Survey (USGS) created a set of educational lessons based on the RMS Titanic's April 1912 sailing. With these lessons, student researchers can learn about latitude and longitude, map projections, ocean currents, databases, maps, and images through the analysis of the route, warnings, sinking, rescue, and eventual discovery of the submerged ocean liner in 1985. They can also consider the human and physical aspects of the maiden voyage in the North Atlantic Ocean at a variety of scales, from global to regional to local. Likewise, their investigations can reveal how the sinking of the Titanic affected future shipping routes.

  8. Ethane ocean on Titan

    Science.gov (United States)

    Lunine, J. I.; Stevenson, D. J.; Yung, Y.L.

    1983-01-01

    Voyager I radio occultation data is employed to develop a qualitative model of an ethane ocean on Titan. It is suggested that the ocean contains 25 percent CH4 and that the ocean is in dynamic equilibrium with an N2 atmosphere. Previous models of a CH4 ocean are discounted due to photolysis rates of CH4 gas. Tidal damping of Titan's orbital eccentricity is taken as evidence for an ocean layer approximately 1 km deep, with the ocean floor being covered with a solid C2H2 layer 100 to 200 m thick. The photolytic process disrupting the CH4, if the estimates of the oceanic content of CH4 are correct, could continue for at least one billion years. Verification of the model is dependent on detecting CH4 clouds in the lower atmosphere, finding C2H6 saturation in the lower troposphere, or obtaining evidence of a global ocean.

  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. Giant Magnetoelectric Energy Conversion Utilizing Inter-Ferroelectric Phase Transformations in Ferroics

    Science.gov (United States)

    Finkel, Peter; Staruch, Margo

    Phase transition-based electromechanical transduction permits achieving a non-resonant broadband mechanical energy conversion see (Finkel et al Actuators, 5 [1] 2. (2015)) , the idea is based on generation high energy density per cycle , at least 100x of magnitude larger than linear piezoelectric type generators in stress biased [011]cut relaxor ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystal can generate reversible strain >0.35% at remarkably low fields (0.1 MV/m) for tens of millions of cycles. Recently we demonstrated that large strain and polarization rotation can be generated for over 40 x 106cycles with little fatigue by realization of reversible ferroelectric-ferroelectric phase transition in [011] cut PIN-PMN-PT relaxor ferroelectric single crystal while sweeping through the transition with a low applied electric field <0.18 MV/m under mechanical stress. This methodology was extended in the present work to propose magnetoelectric (ME) composite hybrid system comprised of highly magnetostrictive alloymFe81.4Ga18.6 (Galfenol), and lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) domain engineered relaxor ferroelectric single crystal. A small time-varying magnetic field applied to this system causes the magnetostrictive element to expand, and the resulting stress forces the phase change in the relaxor ferroelectric single crystal. ME coupling coefficient was fond to achieve 80 V/cm Oe near the FR-FO phase transition that is at least 100X of magnitude higher than any currently reported values.

  11. 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.

  12. Study of lead free ferroelectrics using overlay technique on thick film microstrip ring resonator

    Directory of Open Access Journals (Sweden)

    Shridhar N. Mathad

    2016-03-01

    Full Text Available The lead free ferroelectrics, strontium barium niobates, were synthesized via the low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. The X band response (complex permittivity at very high frequencies of Ag thick film microstrip ring resonator perturbed with strontium barium niobates (SrxBa1-xNb2O6 in form of bulk and thick film was measured. A new approach for determination of complex permittivity (ε′ and ε′′ in the frequency range 8–12 GHz, using perturbation of Ag thick film microstrip ring resonator (MSRR, was applied for both bulk and thick film of strontium barium niobates (SrxBa1-xNb2O6. The microwave conductivity of the bulk and thick film lie in the range from 1.779 S/cm to 2.874 S/cm and 1.364 S/cm to 2.296 S/cm, respectively. The penetration depth of microwave in strontium barium niobates is also reported.

  13. High temperature dielectric and ferroelectric properties of La-modified PbTiO3 nanoceramics

    International Nuclear Information System (INIS)

    Shukla, Archana; Shukla, Namrata; Choudhary, R.N.P.

    2016-01-01

    Ferroelectric materials with high Curie temperature (higher than 300 °C) are highly desirable to construct transducers for high-temperature piezoelectric applications. Among the ferroelectric materials, PbTiO 3 (PT) is considered to be one of the most promising materials. However, the fabrication of high density pure PT ceramics is very difficult because of the highly anisotropy, which limited the use in piezoelectric transducers. Usually, substitutions towards A or B-site of PT may reduce the high anisotropy. The present work reports the experimental investigations on the effect of lanthanum (La 3+ ) substitution on the structural, dielectric and piezoelectric properties of lead titanate (PT) ceramic at high-temperature (RT ∼ 600°C)

  14. Growth and characterization of epitaxial thin films and multiferroic heterostructures of ferromagnetic and ferroelectric materials

    Science.gov (United States)

    Mukherjee, Devajyoti

    Multiferroic materials exhibit unique properties such as simultaneous existence of two or more of coupled ferroic order parameters (ferromagnetism, ferroelectricity, ferroelasticity or their anti-ferroic counterparts) in a single material. Recent years have seen a huge research interest in multiferroic materials for their potential application as high density non-volatile memory devices. However, the scarcity of these materials in single phase and the weak coupling of their ferroic components have directed the research towards multiferroic heterostructures. These systems operate by coupling the magnetic and electric properties of two materials, generally a ferromagnetic material and a ferroelectric material via strain. In this work, horizontal heterostructures of composite multiferroic materials were grown and characterized using pulsed laser ablation technique. Alternate magnetic and ferroelectric layers of cobalt ferrite and lead zirconium titanate, respectively, were fabricated and the coupling effect was studied by X-ray stress analysis. It was observed that the interfacial stress played an important role in the coupling effect between the phases. Doped zinc oxide (ZnO) heterostructures were also studied where the ferromagnetic phase was a layer of manganese doped ZnO and the ferroelectric phase was a layer of vanadium doped ZnO. For the first time, a clear evidence of possible room temperature magneto-elastic coupling was observed in these heterostructures. This work provides new insight into the stress mediated coupling mechanisms in composite multiferroics.

  15. Hysteresis loop behaviors of ferroelectric thin films:A Monte Carlo simulation study

    Institute of Scientific and Technical Information of China (English)

    C. M. Bedoya-Hincapi´e; H. H. Ortiz-´Alvarez; E. Restrepo-Parra; J. J. Olaya-Fl´orez; J. E. Alfonso

    2015-01-01

    The ferroelectric response of bismuth titanate Bi4Ti3O12 (BIT) thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms: the electric field applied in the z direction, the nearest dipole–dipole interaction in the transversal (x–y) direction, and the nearest dipole–dipole interaction in the direction perpendicular to the thin film (the z axis). In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response.

  16. Hysteresis loop behaviors of ferroelectric thin films: A Monte Carlo simulation study

    Science.gov (United States)

    M. Bedoya-Hincapié, C.; H. Ortiz-Álvarez, H.; Restrepo-Parra, E.; J. Olaya-Flórez, J.; E. Alfonso, J.

    2015-11-01

    The ferroelectric response of bismuth titanate Bi4Ti3O12 (BIT) thin film is studied through a Monte Carlo simulation of hysteresis loops. The ferroelectric system is described by using a Diffour Hamiltonian with three terms: the electric field applied in the z direction, the nearest dipole-dipole interaction in the transversal (x-y) direction, and the nearest dipole-dipole interaction in the direction perpendicular to the thin film (the z axis). In the sample construction, we take into consideration the dipole orientations of the monoclinic and orthorhombic structures that can appear in BIT at low temperature in the ferroelectric state. The effects of temperature, stress, and the concentration of pinned dipole defects are assessed by using the hysteresis loops. The results indicate the changes in the hysteresis area with temperature and stress, and the asymmetric hysteresis loops exhibit evidence of the imprint failure mechanism with the emergence of pinned dipolar defects. The simulated shift in the hysteresis loops conforms to the experimental ferroelectric response. Project sponsored by the research departments of the Universidad Nacional de Colombia DIMA and DIB under Project 201010018227-“Crecimiento y caracterización eléctrica y estructural de películas delgadas de BixTiyOz producidas mediante Magnetrón Sputtering” and Project 12920-“Desarrollo teóricoexperimental de nanoestructuras basadas en Bismuto y materiales similares” and “Bisnano Project.”

  17. Directly patternable high refractive index ferroelectric sol–gel resist

    Energy Technology Data Exchange (ETDEWEB)

    Garoli, D., E-mail: denis.garoli@iit.it [Istituto Italiano di Tecnologia, Via Morego 16, 16136 Genova (Italy); Della Giustina, G. [Industrial Engineering Department, University of Padova and INSTM, Via Marzolo 9, 35131 Padova (Italy)

    2015-08-15

    The development of a ferroelectric negative tone sol–gel resist for Ultraviolet (UV) and Electron Beam (EB) lithography is presented. A new system based on Lead Zirconate Titanate (PZT, with formula PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}) was synthesized by sol–gel method. The lithographic performances were investigated and several structures spanning from the micron range down to less than 50 nm have been achieved by UV and EB lithography. The system interaction with UV light and Electron beam was thoroughly characterized by FT-IT spectroscopy. The exposed PZT was annealed at high temperatures in order to study the crystalline phase evolution, the optical constants values and stability of patterned structures. After exposure and annealing, the refractive index of the material can vary from 1.68 up to 2.33 (@400 nm), while the ferroelectric behaviour seems to be maintained after high temperature annealing. These results suggest a possible application of PZT resist not only as ferroelectric but also as nanopatternable high refractive index material. Moreover, direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified and the potentiality for the preparation of high aspect ratio hollow nanostructures will be presented. - Highlights: • A new formula directly patternable PZT high refractive index resist is presented. • The gel is sensitive to both UV and electron beam exposure. • The refractive index can vary from 1.68 up to 2.33 (@400 nm). • Direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified. • High aspect ratio hollow nanostructures will be presented.

  18. Titan's methane clock

    Science.gov (United States)

    Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

    2010-04-01

    Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

  19. Coexistence of weak ferromagnetism and ferroelectricity in the high pressure LiNbO3-type phase of FeTiO3.

    Science.gov (United States)

    Varga, T; Kumar, A; Vlahos, E; Denev, S; Park, M; Hong, S; Sanehira, T; Wang, Y; Fennie, C J; Streiffer, S K; Ke, X; Schiffer, P; Gopalan, V; Mitchell, J F

    2009-07-24

    We report the magnetic and electrical characteristics of polycrystalline FeTiO_{3} synthesized at high pressure that is isostructural with acentric LiNbO_{3} (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below approximately 120 K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

  20. Ferroelectricity in undoped hafnium oxide

    International Nuclear Information System (INIS)

    Polakowski, Patrick; Müller, Johannes

    2015-01-01

    We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4–20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P r of up to 10 μC cm −2 as well as a read/write endurance of 1.6 × 10 5 cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems

  1. Ferroelectric negative capacitance domain dynamics

    Science.gov (United States)

    Hoffmann, Michael; Khan, Asif Islam; Serrao, Claudy; Lu, Zhongyuan; Salahuddin, Sayeef; Pešić, Milan; Slesazeck, Stefan; Schroeder, Uwe; Mikolajick, Thomas

    2018-05-01

    Transient negative capacitance effects in epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 capacitors are investigated with a focus on the dynamical switching behavior governed by domain nucleation and growth. Voltage pulses are applied to a series connection of the ferroelectric capacitor and a resistor to directly measure the ferroelectric negative capacitance during switching. A time-dependent Ginzburg-Landau approach is used to investigate the underlying domain dynamics. The transient negative capacitance is shown to originate from reverse domain nucleation and unrestricted domain growth. However, with the onset of domain coalescence, the capacitance becomes positive again. The persistence of the negative capacitance state is therefore limited by the speed of domain wall motion. By changing the applied electric field, capacitor area or external resistance, this domain wall velocity can be varied predictably over several orders of magnitude. Additionally, detailed insights into the intrinsic material properties of the ferroelectric are obtainable through these measurements. A new method for reliable extraction of the average negative capacitance of the ferroelectric is presented. Furthermore, a simple analytical model is developed, which accurately describes the negative capacitance transient time as a function of the material properties and the experimental boundary conditions.

  2. Titan after Cassini Huygens

    Science.gov (United States)

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

    2008-12-01

    In 2005, the Huygens Probe gave us a snapshot of a world tantalizingly like our own, yet frozen in its evolution on the threshold of life. The descent under parachute, like that of Huygens in 2005, is happening again, but this time in the Saturn-cast twilight of winter in Titan's northern reaches. With a pop, the parachute is released, and then a muffled splash signals the beginning of the first floating exploration of an extraterrestrial sea-this one not of water but of liquid hydrocarbons. Meanwhile, thousands of miles away, a hot air balloon, a "montgolfiere," cruises 6 miles above sunnier terrain, imaging vistas of dunes, river channels, mountains and valleys carved in water ice, and probing the subsurface for vast quantities of "missing" methane and ethane that might be hidden within a porous icy crust. Balloon and floater return their data to a Titan Orbiter equipped to strip away Titan's mysteries with imaging, radar profiling, and atmospheric sampling, much more powerful and more complete than Cassini was capable of. This spacecraft, preparing to enter a circular orbit around Saturn's cloud-shrouded giant moon, has just completed a series of flybys of Enceladus, a tiny but active world with plumes that blow water and organics from the interior into space. Specialized instruments on the orbiter were able to analyze these plumes directly during the flybys. Titan and Enceladus could hardly seem more different, and yet they are linked by their origin in the Saturn system, by a magnetosphere that sweeps up mass and delivers energy, and by the possibility that one or both worlds harbor life. It is the goal of the NASA/ESA Titan Saturn System Mission (TSSM) to explore and investigate these exotic and inviting worlds, to understand their natures and assess the possibilities of habitability in this system so distant from our home world. Orbiting, landing, and ballooning at Titan represent a new and exciting approach to planetary exploration. The TSSM mission

  3. 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.

  4. Titan's Methane Cycle is Closed

    Science.gov (United States)

    Hofgartner, J. D.; Lunine, J. I.

    2013-12-01

    Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

  5. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  6. Cryovolcanism on Titan

    Science.gov (United States)

    Mitri, G.; Showman, A. P.; Lunine, J. I.; Lopes, R. M.

    2008-12-01

    Remote sensing observations yield evidence for cryovolcanism on Titan, and evolutionary models support (but do not require) the presence of an ammonia-water subsurface ocean. The impetus for invoking ammonia as a constituent in an internal ocean and cryovolcanic magma comes from two factors. First, ammonia-water liquid has a lower freezing temperature than pure liquid water, enabling cryovolcanism under the low- temperature conditions prevalent in the outer Solar System. Second, pure water is negatively buoyant with respect to pure water ice, which discourages eruption from the subsurface ocean to the surface. In contrast, the addition of ammonia to the water decreases its density, hence lessening this problem of negative buoyancy. A marginally positive buoyant ammonia-water mixture might allow effusive eruptions from a subsurface ocean. If the subsurface ocean were positively buoyant, all the ammonia would have been erupted very early in Titan's history. Contrary to this scenario, Cassini-Huygens has so far observed neither a global abundance nor a complete dearth of cryovolcanic features. Further, an ancient cryovolcanic epoch cannot explain the relative youth of Titan's surface. Crucial to invoking ammonia-water resurfacing as the source of the apparently recent geological activity is not how to make ammonia-water volcanism work (because the near neutral buoyancy of the ammonia-water mixture encourages an explanation), but rather how to prevent eruption from occurring so easily that cryovolcanic activity is over early on. Although cryovolcanism by ammonia-water has been proposed as a resurfacing process on Titan, few models have specifically dealt with the problem of how to transport ammonia-water liquid onto the surface. We proposed a model of cryovolcanism that involve cracking at the base of the ice shell and formation of ammonia-water pockets in the ice. While the ammonia-water pockets cannot easily become neutral buoyant and promote effusive eruptions

  7. 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).

  8. Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

    Science.gov (United States)

    Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

    Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

  9. Dynamical symmetry breaking in barium isotopes

    International Nuclear Information System (INIS)

    Rawat, Bir Singh; Chattopadhyay, P.K.

    1997-01-01

    The isotopes of Xe with mass numbers 124, 126, 128, 130 and the isotopes of barium with mass numbers 128, 130, 132, 134 were shown to correspond to the O(6) dynamical symmetry of IBM. In the investigation of the dynamical symmetry breaking in this region, the barium isotopes for departures from O(6) symmetry have been studied

  10. 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

  11. Analysis of barium by isotope mass spectrometry

    International Nuclear Information System (INIS)

    Long Kaiming; Jia Baoting; Liu Xuemei

    2004-01-01

    The isotopic abundance ratios for barium at sub-microgram level are analyzed by thermal surface ionization mass spectrometry (TIMS). Rhenium trips used for sample preparation are firstly treated to eliminate possible barium background interference. During the preparation of barium samples phosphoric acid is added as an emitting and stabilizing reagent. The addition of phosphoric acid increases the collection efficiency and ion current strength and stability for barium. A relative standard deviation of 0.02% for the isotopic abundance ratio of 137 Ba to 138 Ba is achieved when the 138 Ba ion current is (1-3) x 10 -12 A. The experimental results also demonstrate that the isotope fractionation effect is negligibly small in the isotopic analysis of barium

  12. Surface bond contraction and its effect on the nanometric sized lead zirconate titanate

    International Nuclear Information System (INIS)

    Haitao Huang; Sun, Chang Q.; Hing, Peter

    2000-01-01

    The grain size effect of lead zirconate titanate PbZr 1-x Ti x O 3 (PZT, x≥0.6) caused by surface bond contraction has been investigated by using the Landau-Ginsburg-Devonshire (LGD) phenomenological theory. It has been shown that, due to the surface bond contraction, both the Curie temperature and the spontaneous polarization of tetragonal PZT decrease with decreasing grain size. These effects become more significant when the grain size is in the nanometre range. A dielectric anomaly appears with decreasing grain size, which corresponds to a size dependent phase transformation. The ferroelectric critical size below which a loss of ferroelectricity will happen is estimated from the results obtained. (author). Letter-to-the-editor

  13. Titan's Gravitational Field

    Science.gov (United States)

    Schubert, G.; Anderson, J. D.

    2013-12-01

    Titan's gravitational field is inferred from an analysis of archived radio Doppler data for six Cassini flybys. The analysis considers each flyby separately in contrast to the approach of lumping all the data together in a massive inversion. In this way it is possible to gain an improved understanding of the character of each flyby and its usefulness in constraining the gravitational coefficient C22 . Though our analysis is not yet complete and our final determination of C22 could differ from the result we report here by 1 or 2 sigma, we find a best-fit value of C22 equal to (13.21 × 0.17) × 10-6, significantly larger than the value of 10.0 × 10-6 obtained from an inversion of the lumped Cassini data. We also find no determination of the tidal Love number k2. The larger value of C22 implies a moment of inertia factor equal to 0.3819 × 0.0020 and a less differentiated Titan than is suggested by the smaller value. The larger value of C22 is consistent with an undifferentiated model of the satellite. While it is not possible to rule out either value of C22 , we prefer the larger value because its derivation results from a more hands on analysis of the data that extracts the weak hydrostatic signal while revealing the effects of gravity anomalies and unmodeled spacecraft accelerations on each of the six flybys.

  14. Titan's Emergence from Winter

    Science.gov (United States)

    Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

    2011-01-01

    We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

  15. Graded ferroelectrics, transpacitors and transponents

    CERN Document Server

    Mantese, Joseph V

    2005-01-01

    The text details the experimental and theoretical aspects of newly emerging ferroelectric devices, and their extensions to other ferroic systems such as: ferromagnetics, ferroelastics, piezoelectrics, etc. The theory and experimental results pertaining to non-homogeneous active ferroic devices and structures are presented.

  16. Surface Acoustic Waves in ferroelectrics

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Jastrabík, Lubomír; Tarasenko, Alexander

    2004-01-01

    Roč. 298, - (2004), s. 325-333 ISSN 0015-0193 R&D Projects: GA AV ČR IBS1010203 Keywords : Rayleigh waves * ferroelectric films * phase transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  17. Cross-poling textures in a lead zirconate titanate piezoelectric material

    International Nuclear Information System (INIS)

    Wan, Shan; Bowman, Keith J.

    2000-01-01

    Tetragonal ferroelectric materials are polarized to induce the anisotropy necessary for the piezoelectric effect. This poling of the material is inherently an orientation process. Pole figure texture measurements of poling and cross-poling in a lead zirconate titanate Navy VI material show domain motion. The resulting axisymmetric and three-dimensional textures demonstrate the contribution of 90 degree sign domain motion to piezoelectricity. Cross-poling results in strong orientations with lower applied fields than in the initial poling steps. (c) 2000 Materials Research Society

  18. Effect of thermal strain on the ferroelectric phase transition in polycrystalline Ba0.5Sr0.5TiO3 thin films studied by Raman spectroscopy

    International Nuclear Information System (INIS)

    Tenne, D.A.; Soukiassian, A.; Xi, X.X.; Taylor, T.R.; Hansen, P.J.; Speck, J.S.; York, R.A.

    2004-01-01

    We have applied Raman spectroscopy to study the influence of thermal strain on the vibrational properties of polycrystalline Ba 0.5 Sr 0.5 TiO 3 films. The films were grown by rf magnetron sputtering on Pt/SiO 2 surface using different host substrates: strontium titanate, sapphire, silicon, and vycor glass. These substrates provide a systematic change in the thermal strain while maintaining the same film microstructure. From the temperature dependence of the ferroelectric A 1 soft phonon intensity, the ferroelectric phase transition temperature, T C , was determined. We found that T C decreases with increasing tensile stress in the films. This dependence is different from the theoretical predictions for epitaxial ferroelectric films. The reduction of the ferroelectric transition temperature with increasing biaxial tensile strain is attributed to the suppression of in-plane polarization due to the small lateral grain size in the films

  19. Hybrid dual gate ferroelectric memory for multilevel information storage

    KAUST Repository

    Khan, Yasser; Caraveo-Frescas, Jesus Alfonso; Alshareef, Husam N.

    2015-01-01

    Here, we report hybrid organic/inorganic ferroelectric memory with multilevel information storage using transparent p-type SnO semiconductor and ferroelectric P(VDF-TrFE) polymer. The dual gate devices include a top ferroelectric field

  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. 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

  2. A new double contrast barium enema

    International Nuclear Information System (INIS)

    Park, Jun Sang; Cho, Won Sik; Lee, Sung Woo; Lee, Mun Gyu; Jeon, Jeong Dong; Jaun, Woo Ki; Han, Chung Yul

    1987-01-01

    A new technic of the barium enema was proposed for the better colonic double contrast study with the average 204ml of 50w/v% barium, applied to 109 serial patients. The barium was introduced to sigmoid colon, and then pushed to a mid transverse colon by the air insufflation through an enema syringe, a new device. An advance to cecum is accomplished by the air insufflation and/or the position change of the patient. The barium transfer method was developed for the best spot film exposure, through colon, by the position change of the patient, the tilting of the x-ray table and the air insufflation with the enema syringe. The mean angle of the x-ray table tilted was -10 .deg. at the beginning the barium enema till the barium sent past the splenic flexure, -15 . deg. for the best lateral view of rectum and -18 .deg. for the bet prone PA view of rectosigmoid colon. This was a simple, better and economic double contrast barium enema for the cooperative patients

  3. The age of Titan's surface

    Science.gov (United States)

    Neish, C. D.; Lorenz, R. D.

    2010-04-01

    High-resolution images of the surface of Titan taken by the Cassini spacecraft reveal a world with an extreme paucity of impact craters. Planetary surfaces are commonly dated by dividing the number of impact craters by the estimated impactor flux, but this approach has been confounded at Titan by several difficulties. First, high-resolution imaging of the surface of Titan is far from complete (in the near-infrared as well as radar). As of December 2007, Cassini RADAR images covered only 22% of its surface. However, we can use Monte-Carlo models to explore how many craters of a given size (with large or very large craters being of particular interest) may be present in the unobserved areas. Second, literature descriptions of the crater formation rate (e.g. Korycansky and Zahnle 2005 and Artemieva and Lunine 2005) are apparently not in agreement. We discuss possible resolutions. Third, since surface modification processes are ongoing, the actual number of craters on Titan's surface remains uncertain, as craters may be eroded beyond recognition, or obscured by lakes or sand seas. In this connection, we use the Earth as an analogue. The Earth is in many ways the most "Titan-like" world in the solar system, with extensive modification by erosion, burial, tectonism, and volcanism. We compare the observed number of terrestrial craters to the expected terrestrial impactor flux to determine the crater reduction factor for a world similar to Titan. From this information, we can back out the actual number of craters on Titan's surface and estimate its crater retention age. An accurate age estimate will be critical for constraining models of Titan's formation and evolution.

  4. Monosodium titanate particle characterization

    International Nuclear Information System (INIS)

    Chandler, G.T.; Hobbs, D.T.

    1993-01-01

    A characterization study was performed on monosodium titanate (MST) particles to determine the effect of high shear forces expected from the In-Tank Precipitation (ITP) process pumps on the particle size distribution. The particles were characterized using particle size analysis and scanning electron microscopy (SEM). No significant changes in particle size distributions were observed between as-received MST and after 2--4 hours of shearing. Both as-received and sheared MST particles contained a large percentage of porosity with pore sizes on the order of 500 to 2,000 Angstroms. Because of the large percentage of porosity, the overall surface area of the MST is dominated by the internal surfaces. The uranium and plutonium species present in the waste solution will have access to both interior and exterior surfaces. Therefore, uranium and plutonium loading should not be a strong function of MST particle size

  5. Chemistry in Titan

    Science.gov (United States)

    Plessis, S.; Carrasco, N.; Pernot, P.

    2009-04-01

    Modelling the chemical composition of Titan's ionosphere is a very challenging issue. Latest works perform either inversion of CASSINI's INMS mass spectra (neutral[1] or ion[2]), or design coupled ion-neutral chemistry models[3]. Coupling ionic and neutral chemistry has been reported to be an essential feature of accurate modelling[3]. Electron Dissociative Recombination (EDR), where free electrons recombine with positive ions to produce neutral species, is a key component of ion-neutral coupling. There is a major difficulty in EDR modelling: for heavy ions, the distribution of neutral products is incompletely characterized by experiments. For instance, for some hydrocarbon ions only the carbon repartition is measured, leaving the hydrogen repartition and thus the exact neutral species identity unknown[4]. This precludes reliable deterministic modelling of this process and of ion-neutral coupling. We propose a novel stochastic description of the EDR chemical reactions which enables efficient representation and simulation of the partial experimental knowledge. The description of products distribution in multi-pathways reactions is based on branching ratios, which should sum to unity. The keystone of our approach is the design of a probability density function accounting for all available informations and physical constrains. This is done by Dirichlet modelling which enables one to sample random variables whose sum is constant[5]. The specifics of EDR partial uncertainty call for a hierarchiral Dirichlet representation, which generalizes our previous work[5]. We present results on the importance of ion-neutral coupling based on our stochastic model. C repartition H repartition (measured) (unknown ) → C4H2 + 3H2 + H .. -→ C4 . → C4H2 + 7H → C3H8. + CH C4H+9 + e- -→ C3 + C .. → C3H3 + CH2 + 2H2 → C2H6 + C2H2 + H .. -→ C2 + C2 . → 2C2H2 + 2H2 + H (1) References [1] J. Cui, R.V. Yelle, V. Vuitton, J.H. Waite Jr., W.T. Kasprzak

  6. Methane rain on Titan

    Science.gov (United States)

    Toon, Owen B.; Mckay, Christopher P.; Courtin, Regis; Ackerman, Thomas P.

    1988-01-01

    The atmosphere of Titan is characterized by means of model computations based on Voyager IRIS IR spectra and published data from laboratory determinations of absorption coefficients and cloud refractive indices. The results are presented in tables and graphs, and it is pointed out that the presence of Ar is not required in the model. Particular attention is given to the role of CH4, which is found to form patchy clouds (with particle radii of 50 microns or greater and visible/IR optical depths of 2-5) at altitudes up to about 30 km. The mechanisms by which such rain-sized particles could form are discussed, and it is suggested that the observed 500-600/cm spectrum is affected much less by the CH4 clouds than by H2 or variations in the temperature of the high-altitude haze.

  7. 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.

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

    International Nuclear Information System (INIS)

    1990-01-01

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

  9. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    Kinnunen, J.; Pietilae, J.; Ahovuo, J.; Mankinen, P.; Tervahartiala, P.

    1989-01-01

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

  10. Atomization mechanisms for barium in furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Styris, D.L.

    1984-01-01

    Atomic absorption spectrometry and mass spectrometry are used simultaneously in order to elucidate atomization mechanisms of barium dichloride in pyrolytic graphite, vitreous carbon, and tantalum furnaces. Gas-phase barium dicarbide is observed to appear concurrently with the free barium. Barium oxide and barium dihydroxide precursors appear with the chlorides. Surface reactions involving species that are absorbed on the various furnaces are postulated to explain the appearances of the species that are observed in the gas phase. 49 references, 4 figures, 1 table

  11. Percolation Magnetism in Ferroelectric Nanoparticles

    Science.gov (United States)

    Golovina, Iryna S.; Lemishko, Serhii V.; Morozovska, Anna N.

    2017-06-01

    Nanoparticles of potassium tantalate (KTaO3) and potassium niobate (KNbO3) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

  12. Quantum fluctuations in insulating ferroelectrics

    International Nuclear Information System (INIS)

    Riseborough, Peter S.

    2010-01-01

    Graphical abstract: It has been proposed that in a ferroelectric insulator, an applied magnetic field may couple the transverse phonon modes and produce left and right circularly polarized phonon modes which are no longer degenerate. We quantize the theory and examine the effects of quantal fluctuations. In particular, we show that the zero point fluctuations result in a large diamagnetic contribution to the magnetic susceptibility. - Abstract: It has been proposed that in a ferroelectric insulator, an applied magnetic field may couple the transverse phonon modes and produce left and right circularly polarized phonon modes which are no longer degenerate. We quantize the theory and examine the effects of quantal fluctuations. In particular, we show that the zero-point fluctuations result in a large diamagnetic contribution to the magnetic susceptibility.

  13. Percolation Magnetism in Ferroelectric Nanoparticles.

    Science.gov (United States)

    Golovina, Iryna S; Lemishko, Serhii V; Morozovska, Anna N

    2017-12-01

    Nanoparticles of potassium tantalate (KTaO 3 ) and potassium niobate (KNbO 3 ) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe 3+ ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.

  14. Guest Editoria, Ferroelectrics, 323, 1

    OpenAIRE

    Krupanidhi, SB

    2005-01-01

    The Fourth Asian Meeting on Ferroelectricity (AMF-4)was organized at the Indian Institute of Science, Bangalore, INDIA during December 12–15, 2003. The organization of the conferencewas cosponsored by various agencies which included the Department of Science & Technology (DST), Defense R&D Organization (DRDO), Council of Scientific and Industrial Research (CSIR), Materials Research Society of India (MRSI), Indian Institute of Science (IISC), IEEE UFFC (USA), Taylor and Francis Scientific P...

  15. Time requirement for barium reduction in intussusception

    International Nuclear Information System (INIS)

    Hwang, Hye Eun; Kim, Seung Ho; Kang, In Young; Park, Byoung Lan; Kim, Byoung Geun

    1988-01-01

    During the period between January 1985 and December 1987, barium reduction was performed in 146 cases of intussusception who were admitted to Kwangju Christian Hospital. The results were as follows: 1. Success rate to the symptom duration is relatively constant. 2. The success rate in infants with severe dehydration was 50% but it was gradually increased in infants with moderate dehydration and in infants with mild dehydration, 83.3% and 100% respectively. 3. The success rate of 12 cases in severely dehydrated infants with positive dissection sign was 16.7%. 4. The success rate of 15 cases in moderately dehydrated infants with positive dissection sign was 66.7%. 5. The average time requirement for barium reduction was 58.3 minutes. No serious complications were noted during barium reduction, except mild vomiting. 6. With above results, it is desirable that barium reduction should be performed according to the patient's physical status and radiologic findings.

  16. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  17. Barium appendicitis after upper gastrointestinal imaging.

    Science.gov (United States)

    Novotny, Nathan M; Lillemoe, Keith D; Falimirski, Mark E

    2010-02-01

    Barium appendicitis (BA) is a rarely seen entity with fewer than 30 reports in the literature. However, it is a known complication of barium imaging. To report a case of BA in a patient whose computed tomography (CT) scan was initially read as foreign body ingestion. An 18-year-old man presented with right lower quadrant pain after upper gastrointestinal imaging 2 weeks prior. A CT scan was obtained of his abdomen and pelvis that revealed a finding that was interpreted as a foreign body at the area of the terminal ileum. A plain X-ray study of the abdomen revealed radiopaque appendicoliths. Pathology confirmed the diagnosis of barium appendicitis. BA is a rare entity and the pathogenesis is unclear. Shorter intervals between barium study and presentation with appendicitis usually correlate with fewer complications. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  18. Influence of lanthanum distribution on dielectric and ferroelectric properties of BaBi4-xLaxTi4O15 ceramics

    International Nuclear Information System (INIS)

    Khokhar, Anita; Goyal, Parveen K.; Thakur, O.P.; Shukla, A.K.; Sreenivas, K.

    2015-01-01

    Structural and electrical properties of Lanthanum substituted barium bismuth titanate BaBi 4-x La x Ti 4 O 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 2 O 2 ) 2+ layers of BaBi 4 Ti 4 O 15 ceramics. Room temperature dielectric constant (ε′) increases and considerable reduction in the low frequency (10 −2 to 10 Hz) dielectric losses and in dc conductivity (σ dc ) are seen with lanthanum substitution. A critical La content of x ∼0.20 in BaBi 4-x La x Ti 4 O 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 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 2 O 2 ) 2+ layers as evidenced through the Raman spectroscopy. - Highlights: • La distribution in BaBi 4-x La x Ti 4 O 15 ceramics is analyzed through Raman spectroscopy. • Low and a nearly constant loss over wide frequency range (10 −2 –10 7  Hz) obtained. • Critical La content x = 0.2 identified for high resistivity and ideal relaxor characteristics. • Improved P-E hysteresis loops and large remnant polarization measured. • Changes in the

  19. Unveiling the Role of CNTs on the Phase Formation of 1D Ferroelectrics

    KAUST Repository

    Mahajan, Amit

    2015-05-21

    Carbon nanotubes (CNTs) have the potential to act as templates or bottom electrodes for three dimension (3D) capacitor arrays, which utilise one dimension (1D) ferroelectric nanostructures to increase memory size and density. However, growing a ferroelectric on the surface of CNTs is non-trivial. Here, we demonstrate that multi-walled (MW) CNTs decrease the time and temperature for formation of lead zirconium titanate Pb(Zr1-xTix)O3 (PZT) by ~100 ºC commensurate with a decrease in activation energy from 68±15 kJ/mol to 27±2 kJ/mol. As a consequence, monophasic PZT was obtained at 575 ºC for MWCNTs/PZT whereas for pure PZT traces of pyrochlore were still present at 650 ºC, where PZT phase formed due to homogeneous nucleation. The piezoelectric nature of MWCNT/PZT synthesised at 500 ºC for 1 h was proved. Although further work is required to prove the concept of 3D capacitor arrays, our result suggests that it is feasible to utilise MWCNTs as templates/electrodes for the formation of 1D PZT nano ferroelectrics.

  20. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-04-24

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational voltages to achieve coercive electric fields, reduces the sol-gel coating cycles required (i.e., more cost-effective), and, fabrication wise, is more suitable for further scaling of lateral dimensions to the nano-scale due to the larger feature size-to-depth aspect ratio (critical for ultra-high density non-volatile memory applications). Utilizing the inverse proportionality between substrate\\'s thickness and its flexibility, traditional PZT based FeRAM on silicon is transformed through a transfer-less manufacturable process into a flexible form that matches organic electronics\\' flexibility while preserving the superior performance of silicon CMOS electronics. Each memory cell in a FeRAM array consists of two main elements; a select/access transistor, and a storage ferroelectric capacitor. Flexible transistors on silicon have already been reported. In this work, we focus on the storage ferroelectric capacitors, and report, for the first time, its performance after transformation into a flexible version, and assess its key memory parameters while bent at 0.5 cm minimum bending radius.

  1. Titan Montgolfiere Terrestrial Test Bed, Phase II

    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...

  2. Titan Montgolfiere Terrestrial Test Bed, Phase I

    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...

  3. Neutral barium cloud evolution at different altitudes

    International Nuclear Information System (INIS)

    Li Lei; Xu Ronglan

    2002-01-01

    Considering the joint effects of diffusion, collision, oxidation and photoionization, the authors 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 260 km. This can be divided into oxidation, oxidation plus photoionization and photoionization regions

  4. Polymer Ferroelectric Memory for Flexible Electronics

    KAUST Repository

    Khan, Mohd Adnan

    2013-11-01

    With the projected growth of the flexible and plastic electronics industry, there is renewed interest in the research community to develop high performance all-polymeric memory which will be an essential component of any electronic circuit. Some of the efforts in polymer memories are based on different mechanisms such as filamentary conduction, charge trapping effects, dipole alignment, and reduction-oxidation to name a few. Among these the leading candidate are those based on the mechanism of ferroelectricity. Polymer ferroelectric memory can be used in niche applications like smart cards, RFID tags, sensors etc. This dissertation will focus on novel material and device engineering to fabricate high performance low temperature polymeric ferroelectric memory for flexible electronics. We address and find solutions to some fundamental problems affecting all polymer ferroelectric memory like high coercive fields, fatigue and thermal stability issues, poor breakdown strength and poor p-type hole mobilities. Some of the strategies adopted in this dissertation are: Use of different flexible substrates, electrode engineering to improve charge injection and fatigue properties of ferroelectric polymers, large area ink jet printing of ferroelectric memory devices, use of polymer blends to improve insulating properties of ferroelectric polymers and use of oxide semiconductors to fabricate high mobility p-type ferroelectric memory. During the course of this dissertation we have fabricated: the first all-polymer ferroelectric capacitors with solvent modified highly conducting polymeric poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS] electrodes on plastic substrates with performance as good as devices with metallic Platinum-Gold electrodes on silicon substrates; the first all-polymer high performance ferroelectric memory on banknotes for security applications; novel ferroelectric capacitors based on blends of ferroelectric poly(vinylidene fluoride

  5. Polymer Ferroelectric Memory for Flexible Electronics

    KAUST Repository

    Khan, Mohd Adnan

    2013-01-01

    With the projected growth of the flexible and plastic electronics industry, there is renewed interest in the research community to develop high performance all-polymeric memory which will be an essential component of any electronic circuit. Some of the efforts in polymer memories are based on different mechanisms such as filamentary conduction, charge trapping effects, dipole alignment, and reduction-oxidation to name a few. Among these the leading candidate are those based on the mechanism of ferroelectricity. Polymer ferroelectric memory can be used in niche applications like smart cards, RFID tags, sensors etc. This dissertation will focus on novel material and device engineering to fabricate high performance low temperature polymeric ferroelectric memory for flexible electronics. We address and find solutions to some fundamental problems affecting all polymer ferroelectric memory like high coercive fields, fatigue and thermal stability issues, poor breakdown strength and poor p-type hole mobilities. Some of the strategies adopted in this dissertation are: Use of different flexible substrates, electrode engineering to improve charge injection and fatigue properties of ferroelectric polymers, large area ink jet printing of ferroelectric memory devices, use of polymer blends to improve insulating properties of ferroelectric polymers and use of oxide semiconductors to fabricate high mobility p-type ferroelectric memory. During the course of this dissertation we have fabricated: the first all-polymer ferroelectric capacitors with solvent modified highly conducting polymeric poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT:PSS] electrodes on plastic substrates with performance as good as devices with metallic Platinum-Gold electrodes on silicon substrates; the first all-polymer high performance ferroelectric memory on banknotes for security applications; novel ferroelectric capacitors based on blends of ferroelectric poly(vinylidene fluoride

  6. The atmospheric temperature structure of Titan

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, J. B.; Courtin, Regis; Lunine, Jonathan I.

    1992-01-01

    The contribution of various factors to the thermal structure of Titan's past and present atmosphere are discussed. A one dimensional model of Titan's thermal structure is summarized. The greenhouse effect of Titan's atmosphere, caused primarily by pressure induced opacity of N2, CH4, and H2, is discussed together with the antigreenhouse effect dominated by the haze which absorbs incident sunlight. The implications for the atmosphere of the presence of an ocean on Titan are also discussed.

  7. Studies on various properties of pure and Li-doped Barium Hydrogen Phosphate (BHP) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nallamuthu, D. [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Selvarajan, P., E-mail: pselvarajanphy@yahoo.co.i [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Freeda, T.H. [Physics Research Centre, S.T. Hindu College, Nagercoil 629002 (India)

    2010-12-15

    Single crystals of pure and Li-doped barium hydrogen phosphate (BHP) were grown by solution method with gel technique. Various properties of the harvested crystals were studied by carrying out single crystal and powder XRD, FTIR, TG/DTA, microhardness and dielectric studies. Atomic absorption study was carried out for Li-doped BHP crystal to check the presence of Li dopants. Unit cell dimensions and diffracting planes of the grown crystals have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Density of the grown crystals was calculated using the XRD data. Thermal stability of the samples was checked by TG/DTA studies. Mechanical and dielectric characterizations of the harvested pure and Li-doped BHP crystals reveal the mechanical strength and ferroelectric transition. The observed results are reported and discussed.

  8. 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.

  9. An experimental study on barium peritonitis in rats

    International Nuclear Information System (INIS)

    Kang, Heung Sik; Han, Man Chung; Kim, Chu Wan

    1985-01-01

    Barium sulfate is universally used contrast media in gastrointestinal roentgenology, and spillage of barium into peritoneal cavity can occur. The references on effect of barium sulfate in the peritoneal cavity have been scattered and the results are varied. In 80 rats, body weight of 130 gm to 150 gm, sterile pure barium, sterile commercial barium, intestinal content, and mixed pure barium and intestinal content were experimentally injected into the peritoneal cavity. Consecutive weekly laparotomy and microscopic examination were done for 4 weeks. The results are as followings: 1. Mind inflammatory reaction and mild adhesion after sterile pure barium injection. 2. Mild inflammatory reaction and moderate adhesion after sterile commercial barium injection. 3. Acute peritonitis and abscess formation after intestinal content injection. 4. High mortality due to severe acute peritonitis, and severe adhesion in survivors after injection of both pure barium and intestinal content.

  10. 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.

  11. A concept of ferroelectric microparticle propulsion thruster

    International Nuclear Information System (INIS)

    Yarmolich, D.; Vekselman, V.; Krasik, Ya. E.

    2008-01-01

    A space propulsion concept using charged ferroelectric microparticles as a propellant is suggested. The measured ferroelectric plasma source thrust, produced mainly by microparticles emission, reaches ∼9x10 -4 N. The obtained trajectories of microparticles demonstrate that the majority of the microparticles are positively charged, which permits further improvement of the thruster

  12. Fatigue and retention in ferroelectric Y-Ba-Cu-O/Pb-Zr-Ti-O/Y-Ba-Cu-O heterostructures

    Science.gov (United States)

    Ramesh, R.; Chan, W. K.; Wilkens, B.; Gilchrist, H.; Sands, T.; Tarascon, J. M.; Keramidas, V. G.; Fork, D. K.; Lee, J.; Safari, A.

    1992-09-01

    Fatigue and retention characteristics of ferroelectric lead zirconate titanate thin films grown with Y-Ba-Cu-O(YBCO) thin-film top and bottom electrodes are found to be far superior to those obtained with conventional Pt top electrodes. The heterostructures reported here have been grown in situ by pulsed laser deposition on yttria-stabilized ZrO2 buffer [100] Si and on [001] LaAlO3. Both the a- and c-axis orientations of the YBCO lattice have been used as electrodes. They were prepared using suitable changes in growth conditions.

  13. Structure-Function Relationships of Ferroelectric Polymers.

    Science.gov (United States)

    Pavlopoulou, Eleni; Maiz, Jon; Spampinato, Nicoletta; Maglione, Mario; Hadziioannou, Georges

    Poly(vinylidene fluoride), PVDF, and its copolymers with trifluoroethylene, P(VDF-co-TrFE) have been long appreciated for their excellent ferroelectric properties. Although they have been mainly studied in the 80s and 90s, understanding their performance is still lacking. Yet the increasing use of P(VDF-co-TrFE) thin films in organic electronic devices during the last ten years revives the need for apprehending the function of these materials. In this work we investigate the structure of P(VDF-co-TrFE) films and correlate it to their ferroelectric properties. Our results show that ferroelectric performance is solely driven by the fraction of polymer that has been crystallized in the ferroelectric phases of PVDF. The relations between remnant polarization, coercive field and dipole switching rate of P(VDF-co-TrFE) with the ferroelectric crystallinity are demonstrated. The French Research Agency (ANR), the Aquitaine Region, Arkema and STMicroelectronics are kindly acknowledged for financial support.

  14. Ferroelectric Electron Emission Principles and Technology

    CERN Document Server

    Riege, H

    1997-01-01

    The spontaneous electrical polarization of ferroelectric materials can be changed either by reversal or by phase transition from a ferroelectric into a non-ferroelectric state or vice versa. If spontaneous polarization changes are induced with fast heat, mechanical pressure, laser or electric field pulses on a submicrosecond time scale, strong uncompensated surface charge densities and related polarization fields are generated, which may lead to the intense self-emission of electrons from the negatively charged free surface areas of the ferroelectric sample. Hence, electron guns can be built with extraction-field-free ferroelectric cathodes, which may be easily separated from the high-field regions of post-accelerating gap structures. The intensity, the energy, the temporal and spatial distribution, and the repetitition rate of the emitted electron beams can be controlled within wide limits via the excitation pulses and external focusing and accelerating electromagnetic fields. The technological advantages an...

  15. 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.

  16. 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.

  17. Diurnal variations of Titan's ionosphere

    Science.gov (United States)

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

    2009-06-01

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

  18. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites

    Directory of Open Access Journals (Sweden)

    Gollapudi Sreenivasulu

    2016-02-01

    Full Text Available Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i a bimorph of oppositely-poled lead zirconate titanate (PZT platelets and (ii a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

  19. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites.

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-02-20

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

  20. Calorimetric measurements on hafnium titanate

    International Nuclear Information System (INIS)

    Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

    2012-01-01

    Owing to its desirable nuclear and mechanical properties such as good absorption cross-section for thermal neutrons (105 barns), hafnium titanate (HfTiO 4 ) finds application as control rods for nuclear reactors. An accurate knowledge of the thermo physical properties of this material is necessary for design of control rod and for modeling its performance. Heat capacity is an important thermodynamic property that determines the temperature dependent variation of all other thermodynamic properties. Hence enthalpy increments of hafnium titanate (HfTiO 4 ) were measured in the temperature range 803-1663 K by employing the method of inverse drop calorimetry using high temperature differential calorimeter

  1. Titan's hydrodynamically escaping atmosphere

    Science.gov (United States)

    Strobel, Darrell F.

    2008-02-01

    The upper atmosphere of Titan is currently losing mass at a rate ˜(4-5)×10 amus, by hydrodynamic escape as a high density, slow outward expansion driven principally by solar UV heating by CH 4 absorption. The hydrodynamic mass loss is essentially CH 4 and H 2 escape. Their combined escape rates are restricted by power limitations from attaining their limiting rates (and limiting fluxes). Hence they must exhibit gravitational diffusive separation in the upper atmosphere with increasing mixing ratios to eventually become major constituents in the exosphere. A theoretical model with solar EUV heating by N 2 absorption balanced by HCN rotational line cooling in the upper thermosphere yields densities and temperatures consistent with the Huygens Atmospheric Science Investigation (HASI) data [Fulchignoni, M., and 42 colleagues, 2005. Nature 438, 785-791], with a peak temperature of ˜185-190 K between 3500-3550 km. This model implies hydrodynamic escape rates of ˜2×10 CHs and 5×10 Hs, or some other combination with a higher H 2 escape flux, much closer to its limiting value, at the expense of a slightly lower CH 4 escape rate. Nonthermal escape processes are not required to account for the loss rates of CH 4 and H 2, inferred by the Cassini Ion Neutral Mass Spectrometer (INMS) measurements [Yelle, R.V., Borggren, N., de la Haye, V., Kasprzak, W.T., Niemann, H.B., Müller-Wodarg, I., Waite Jr., J.H., 2006. Icarus 182, 567-576].

  2. Interaction of Titan's atmosphere with Saturn's magnetosphere

    International Nuclear Information System (INIS)

    Hartle, R.E.

    1985-01-01

    The Voyager 1 measurements made during the Titan flyby reveal that Saturn's rotating magnetospheric plasma interacts directly with Titan's neutral atmosphere and ionosphere. This results from the lack of an intrinsic magnetic field at Titan. The interaction induces a magnetosphere which deflects the flowing plasma around Titan and forms a plasma wake downstream. Within the tail of the induced magnetosphere, ions of ionospheric origin flow away from Titan. Just outside Titan's magnetosphere, a substantial ion-exosphere forms from an extensive hydrogen-nitrogen exosphere. The exospheric ions are picked up and carried downstream into the wake by the plasma flowing around Titan. Mass loading produced by the addition of exospheric ions slows the wake plasma down considerably in the vicinity of the magnetopause. 36 references

  3. Characterisation of lead barium zirconate thin films for utilisation of the electrocaloric effect

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, C.P., E-mail: c.p.shaw@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Zhang, Qi, E-mail: q.zhang@cranfield.ac.uk [Surface Engineering and Nanotechnology Institute, Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Correia, T.M., E-mail: Tatiana.correia@ktn-uk.org [Knowledge Transfer Network (United Kingdom); Weaver, P.M., E-mail: paul.weaver@innotecuk.com [InotekUK (United Kingdom)

    2016-08-01

    Characterisation of a composition of Lead Barium Zirconate thin films deposited by a spin coating sol-gel process onto platinised silicon substrates has been undertaken to investigate a potential application utilising the reported electrocaloric properties of the material. Xray diffraction studies revealed that above 700 °C the presence of pyrochlore phase was replaced by ferroelectric phase but the identification of antiferroelectric phases previously reported could not be identified. Wet etching of the films produced an insoluble residue containing only evidence of zirconium out of the original three metals, which resembled a skeletal structure similar to the original rosette morphology of the annealed films. Elemental analysis of the annealed films using EDX indicated a non-target Pb:Ba:Zr ratio, which suggested a reduced Zr content of the films. “Solution-like” rather than “sol-like” nature of the spin coated sol and phase boundary proximity are proposed for reported observations, and a mechanism is proposed to account for the unusual observed trend in dielectric constant. - Highlights: • Characterisation of sol-gel deposited Lead barium zirconnate films. • Absence of previously reported antiferroelectric phase. • Identification of proposed non-PBZ phase. • Anomalous increase in film capacitance with thickness interpreted.

  4. Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

    International Nuclear Information System (INIS)

    Batishko, C.R.; Brimhall, J.L.; Pawlewicz, W.T.; Stahl, K.A.; Toburen, L.H.

    1987-09-01

    Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 550 0 C. This report summarizes the research and provides a sampling of the data taken during the report period

  5. Crystallization of sol-gel derived lead zirconate titanate thin films in argon and oxygen atmospheres

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1994-01-01

    Electron diffraction and high-resolution electron microscopic techniques are applied to reveal the mechanisms of crystallization of 75 nm thin films of ferroelectric lead-zirconate-titanate (PZT). Sol-gel methods, followed by pyrolysis at 350 deg C, were used to provide a common starting point after which a variety of rapid-thermal annealing (RTA) experiments in the temperature range 400-700 deg C were made in argon, oxygen and nitrogen/hydrogen atmospheres. The results are interpreted in terms of the crystal chemical analysis, which points out that partial pressure of oxygen and heating rate are important experimental parameters which must be controlled if ferroelectric perovskite-type Pb 2 ZrTiO 6 , rather than pyrochlore-type Pb 2 ZrTiO 6+x , where O < X < 1 or -1 < X < O, is to be obtained after the RTA step. Thus significant improvements in the crystallization of perovskite-type PZT were clearly demonstrated by using argon atmospheres for the RTA step. The results have significance for the production of high-quality ferroelectric thin films, with improved switching and fatigue characteristics, since even small amounts of the pyrochlore phase prove detrimental for these properties. 18 refs., 1 tab., 10 figs

  6. Crystallization of sol-gel derived lead zirconate titanate thin films in argon and oxygen atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L A [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Brooks, K G [Ecole Polytechnique Federale, Lausanne (Switzerland)

    1994-12-31

    Electron diffraction and high-resolution electron microscopic techniques are applied to reveal the mechanisms of crystallization of 75 nm thin films of ferroelectric lead-zirconate-titanate (PZT). Sol-gel methods, followed by pyrolysis at 350 deg C, were used to provide a common starting point after which a variety of rapid-thermal annealing (RTA) experiments in the temperature range 400-700 deg C were made in argon, oxygen and nitrogen/hydrogen atmospheres. The results are interpreted in terms of the crystal chemical analysis, which points out that partial pressure of oxygen and heating rate are important experimental parameters which must be controlled if ferroelectric perovskite-type Pb{sub 2}ZrTiO{sub 6}, rather than pyrochlore-type Pb{sub 2}ZrTiO{sub 6+x}, where O < X < 1 or -1 < X < O, is to be obtained after the RTA step. Thus significant improvements in the crystallization of perovskite-type PZT were clearly demonstrated by using argon atmospheres for the RTA step. The results have significance for the production of high-quality ferroelectric thin films, with improved switching and fatigue characteristics, since even small amounts of the pyrochlore phase prove detrimental for these properties. 18 refs., 1 tab., 10 figs.

  7. Electrical and mechanical properties of 0.5Ba (Zr0.2Ti0.8)O3-0.5 (Ba0.7Ca0.3)TiO3 (BZT-BCT) lead free ferroelectric ceramics reinforced with Al2O3 nano-oxide

    International Nuclear Information System (INIS)

    Adhikari, Prativa; Mazumder, R.

    2014-01-01

    Piezoelectric ceramics are widely used as actuator, resonator, and spark igniter. Recently, much attention has been paid to prepare 0.5Ba (Zr 0.2 Ti 0.8 )O 3 -0.5 (Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) piezoelectric ceramics because of its good dielectric, piezoelectric properties and environment friendly nature. However, piezoelectric ceramics based on BaTiO 3 suffer from low reliability and poor mechanical properties such as strength and toughness. For practical application improvement of the mechanical properties of BaTiO 3 -based ceramics is strongly required. A novel method has been used to improve the mechanical properties of structural ceramics by reinforcement of oxide (Al 2 O 3 , MgO, ZrO 2 and Stabilized-ZrO 2 ) or non-oxide (SiC) particles. It is well known that electrical properties of ferroelectric ceramics generally degrade with non-ferroelectric additives and decrease in sinterability usually encountered with refractory oxide additives. Use of nano-oxide additives may drastically reduce the amount of additive and electrical property may not degrade much. In this report we would show the electrical and mechanical properties of BZT-BCT with Al 2 O 3 nano oxide additive. Modified BZT-BCT nanocomposites were prepared by mixing and sintering of solid state synthesized Zr, Ca modified barium titanate powder and small amount (0.1-2.0 vol %) of nano-oxides, i.e. Al 2 O 3 . Effect of sintering temperature, time, particle size of the nano-oxide additives on electrical (dielectric constant, loss factor, Curie temperature, d 33 ) and mechanical (flexural strength, fracture toughness, hardness) properties were studied. We obtained ∼ 94% dense BZT-BCT reinforced with Al 2 O 3 nano-oxide at 1300℃ without degrading electrical properties (dielectric constant (4850), low dissipation factor (0.0242)) and superior mechanical properties (flexural strength - 60.3 MPa, Vickers hardness-750-800 MPa). (author)

  8. Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

    Science.gov (United States)

    Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

    2018-04-01

    The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

  9. Dynamic processes of domain switching in lead zirconate titanate under cyclic mechanical loading by in situ neutron diffraction

    International Nuclear Information System (INIS)

    Pojprapai, Soodkhet; Luo, Zhenhua; Clausen, Bjorn; Vogel, Sven C.; Brown, Donald W.; Russel, Jennifer; Hoffman, Mark

    2010-01-01

    The performance of ferroelectric ceramics is governed by the ability of domains to switch. A decrease in the switching ability can lead to degradation of the materials and failure of ferroelectric devices. In this work the dynamic properties of domain reorientation are studied. In situ time-of-flight neutron diffraction is used to probe the evolution of ferroelastic domain texture under mechanical cyclic loading in bulk lead zirconate titanate ceramics. The high sensitivity of neutron diffraction to lattice strain is exploited to precisely analyze the change of domain texture and strain through a full-pattern Rietveld method. These results are then used to construct a viscoelastic model, which explains the correlation between macroscopic phenomena (i.e. creep and recovered deformation) and microscopic dynamic behavior (i.e. ferroelastic switching, lattice strain).

  10. Pressure, temperature, and electric field dependence of phase transformations in niobium modified 95/5 lead zirconate titanate

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Wen D.; Carlos Valadez, J.; Gallagher, John A.; Jo, Hwan R.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, The University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095 (United States); Sahul, Raffi; Hackenberger, Wes [TRS Technologies, 2820 East College Avenue, State College, Pennsylvania 16801 (United States)

    2015-06-28

    Ceramic niobium modified 95/5 lead zirconate-lead titanate (PZT) undergoes a pressure induced ferroelectric to antiferroelectric phase transformation accompanied by an elimination of polarization and a volume reduction. Electric field and temperature drive the reverse transformation from the antiferroelectric to ferroelectric phase. The phase transformation was monitored under pressure, temperature, and electric field loading. Pressures and temperatures were varied in discrete steps from 0 MPa to 500 MPa and 25 °C to 125 °C, respectively. Cyclic bipolar electric fields were applied with peak amplitudes of up to 6 MV m{sup −1} at each pressure and temperature combination. The resulting electric displacement–electric field hysteresis loops were open “D” shaped at low pressure, characteristic of soft ferroelectric PZT. Just below the phase transformation pressure, the hysteresis loops took on an “S” shape, which split into a double hysteresis loop just above the phase transformation pressure. Far above the phase transformation pressure, when the applied electric field is insufficient to drive an antiferroelectric to ferroelectric phase transformation, the hysteresis loops collapse to linear dielectric behavior. Phase stability maps were generated from the experimental data at each of the temperature steps and used to form a three dimensional pressure–temperature–electric field phase diagram.

  11. Hubble Observes Surface of Titan

    Science.gov (United States)

    1994-01-01

    Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much thicker

  12. 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.

  13. Structural Consequences of Ferroelectric Nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    J Young Jo; P Chen; R Sichel; S Bake; R Smith; N Balke; S Kalinin; M Holt; J Maser; et al.

    2011-12-31

    Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has been challenging due to the lack of appropriate structural characterization tools. Synchrotron X-ray nanodiffraction provides images of the domain structure written by PFM into an epitaxial Pb(Zr,Ti)O{sub 3} thin film and simultaneously reveals structural effects arising from the writing process. A coherent scattering simulation including the superposition of the beams simultaneously diffracted by multiple mosaic blocks provides an excellent fit to the observed diffraction patterns. Domains in which the polarization is reversed from the as-grown state have a strain of up to 0.1% representing the piezoelectric response to unscreened surface charges. An additional X-ray microdiffraction study of the photon-energy dependence of the difference in diffracted intensity between opposite polarization states shows that this contrast has a crystallographic origin. The sign and magnitude of the intensity contrast between domains of opposite polarization are consistent with the polarization expected from PFM images and with the writing of domains through the entire thickness of the ferroelectric layer. The strain induced by writing provides a significant additional contribution to the increased free energy of the written domain state with respect to a uniformly polarized state.

  14. Chemical segregation and self polarisation in ferroelectrics

    Directory of Open Access Journals (Sweden)

    Bernard E. Watts

    2009-06-01

    Full Text Available Chemical partitioning or segregation is commonly encountered in solid-state syntheses. It is driven by compositional, thermal and electric field gradients. These phenomena can be quite extreme in thin films and lead to notable effects on the electrical properties of ferroelectrics. The segregation in ferroelectric thin films will be illustrated and the mechanisms explained in terms of diffusion processes driven by a potential gradient of the oxygen. The hypothesis can also explain self polarisation and imprint in ferroelectric hysteresis.

  15. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy.

    Science.gov (United States)

    Tenne, D A; Bruchhausen, A; Lanzillotti-Kimura, N D; Fainstein, A; Katiyar, R S; Cantarero, A; Soukiassian, A; Vaithyanathan, V; Haeni, J H; Tian, W; Schlom, D G; Choi, K J; Kim, D M; Eom, C B; Sun, H P; Pan, X Q; Li, Y L; Chen, L Q; Jia, Q X; Nakhmanson, S M; Rabe, K M; Xi, X X

    2006-09-15

    We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.

  16. Static Characteristics of the Ferroelectric Transistor Inverter

    Science.gov (United States)

    Mitchell, Cody; Laws, crystal; MacLeond, Todd C.; Ho, Fat D.

    2010-01-01

    The inverter is one of the most fundamental building blocks of digital logic, and it can be used as the foundation for understanding more complex logic gates and circuits. This paper presents the characteristics of an inverter circuit using a ferroelectric field-effect transistor. The voltage transfer characteristics are analyzed with respect to varying parameters such as supply voltage, input voltage, and load resistance. The effects of the ferroelectric layer between the gate and semiconductor are examined, and comparisons are made between the inverters using ferroelectric transistors and those using traditional MOSFETs.

  17. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    Energy Technology Data Exchange (ETDEWEB)

    Daranciang, Dan

    2012-02-15

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  18. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    International Nuclear Information System (INIS)

    Daranciang, Dan

    2012-01-01

    We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  19. Coprecipitation of iron and silver with barium fluoride

    International Nuclear Information System (INIS)

    Kopilova, N.V.; Khamidov, B.O.; Kashina, Z.A.; Ikrami, D.D.

    1986-01-01

    Distribution of trace contaminants of iron and silver at coprecipitation of barium fluoride is studied in present work. It is defined that iron almost completely coprecipitated with barium fluoride in wide range of ph 5.5-12. Silver coprecipitated with barium fluoride in ph range 4-7. The value of coprecipitation varies from 94% to 100%.

  20. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium calcium...

  1. Structural and electrical properties of Nd ion modified lead zirconate titanate nanopowders and ceramics

    International Nuclear Information System (INIS)

    Da-Wei, Wang; De-Qing, Zhang; Quan-Liang, Zhao; Hong-Mei, Liu; Zhi-Ying, Wang; Mao-Sheng, Cao; Jie, Yuan

    2009-01-01

    A modified sol-gel method is used for synthesizing Nd ion doped lead zirconate titanate nanopowders Pb 1–3x/2 Nd x Zr 0.52 Ti 0.48 O 3 (PNZT) in an ethylene glycol system with zirconium nitrate as zirconium source. The results show that it is critical to add lead acetate after the reaction of zirconium nitrate with tetrabutyl titanate in the ethylene glycol system for preparing PNZT with an exact fraction of titanium content. It has been observed that the dopant of excess Nd ions can effectively improve the sintered densification and activity of the PNZT ceramics. Piezoelectric, dielectric and ferroelectric properties of the PNZT ceramics are remarkably enhanced as compared with those of monolithic lead zirconate titanate (PZT). Especially, the supreme values of piezoelectric constant (d 33 ) and dielectric constant ( element of ) for the PNZT are both about two times that of the monolithic PZT and moreover, the remnant polarization (P r ) also increases by 30%. According to the analysis of the structures and properties, we attribute the improvement in electrical properties to the lead vacancies caused by the doping of Nd ions

  2. Bismuth Titanate Fabricated by Spray-on Deposition and Microwave Sintering For High-Temperature Ultrasonic Transducers.

    Science.gov (United States)

    Searfass, Clifford T; Pheil, C; Sinding, K; Tittmann, B R; Baba, A; Agrawal, D K

    2016-01-01

    Thick films of ferroelectric bismuth titanate (Bi4Ti3O12) have been fabricated by spray-on deposition in conjunction with microwave sintering for use as high-temperature ultrasonic transducers. The elastic modulus, density, permittivity, and conductivity of the films were characterized. Electro-mechanical properties of the films were estimated with a commercial d33 meter which gave 16 pC/N. This value is higher than typically reported for bulk bismuth titanate; however, these films withstand higher field strengths during poling which is correlated with higher d33 values. Films were capable of operating at 650 °C for roughly 5 min before depoling and can operate at 600 °C for at least 7 days.

  3. Barium ion beam. Annual progress report

    International Nuclear Information System (INIS)

    Lazar, N.; Dandl, R.; Rynn, N.; Wickham, M.

    1985-01-01

    The barium ion beam Zeeman diagnostic is an in situ nonperturbing diagnostic designed to measure both the plasma electric and magnetic fields in devices such as STM and EBT. The diagnostic satisfies the requirements of high precision, spatial resolution and nonperturbation of the plasma. The technique uses resonance absorption of light from a single moded laser in a beam of energetic barium ions to measure the Zeeman effect in the absorption spectrum (to measure changes in the magnetic field) and to observe the changes in beam velocity by the Doppler shift of the absorption lines

  4. Modeling of Toroidal Ordering in Ferroelectric Nanodots

    National Research Council Canada - National Science Library

    Crone, Joshua C; Chung, Peter W

    2007-01-01

    .... Beginning with an introduction of basic concepts, the report reviews the current state-of-the-art of ferroelectric nanodot technology through a literature review and identifies areas of need for continued study...

  5. Negative capacitance in a ferroelectric capacitor.

    Science.gov (United States)

    Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2015-02-01

    The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

  6. Four-state ferroelectric spin-valve

    Czech Academy of Sciences Publication Activity Database

    Quindeau, A.; Fina, I.; Martí, Xavier; Apachitei, G.; Ferrer, P.; Nicklin, C.; Pippel, E.; Hesse, D.; Alexe, M.

    2015-01-01

    Roč. 5, May (2015), 09749 ISSN 2045-2322 Institutional support: RVO:68378271 Keywords : electronic and spintronic devices * ferroelectrics and multiferroics Subject RIV: BE - Theoretical Physics Impact factor: 5.228, year: 2015

  7. Effect of sodium bicarbonate pretreatment on barium coating of mucosa during double contrast barium meal

    International Nuclear Information System (INIS)

    Kinnunen, J.; Toetterman, S.; Kaila, R.; Pietilae, J.; Linden, H.; Tervahartiala, P.

    1983-01-01

    The radiographic pattern of the areae gastricae is produced by barium lying in the intersecting furrows of the gastric mucosal surface. However, if the mucus layer on the gastric mucosa is thick, it interferes with the barium coating of the areae gastricae during double contrast barium meal. As sodium bicarbonate decreases the viscosity of mucus and thus may make the gastric mucus layer thinner, it was evaluated as a pretreatment agent in a routine double contrast upper-gastrointestinal study to improve the visualization of the areae gastricae. In a single blind study, 53 of 106 patients took sodium bicarbonate water mixtures at bedtime the day before and on the morning of the examination. According to the results of the present study mucolysis induced by the used doses of sodium bicarbonate does not significantly affect micromucosal visualization during double-contrast barium meal. (orig.) [de

  8. Effect of sodium bicarbonate pretreatment on barium coating of mucosa during double contrast barium meal

    Energy Technology Data Exchange (ETDEWEB)

    Kinnunen, J.; Toetterman, S.; Kaila, R.; Pietilae, J.; Linden, H.; Tervahartiala, P.

    1983-08-01

    The radiographic pattern of the areae gastricae is produced by barium lying in the intersecting furrows of the gastric mucosal surface. However, if the mucus layer on the gastric mucosa is thick, it interferes with the barium coating of the areae gastricae during double contrast barium meal. As sodium bicarbonate decreases the viscosity of mucus and thus may make the gastric mucus layer thinner, it was evaluated as a pretreatment agent in a routine double contrast upper-gastrointestinal study to improve the visualization of the areae gastricae. In a single blind study, 53 of 106 patients took sodium bicarbonate water mixtures at bedtime the day before and on the morning of the examination. According to the results of the present study mucolysis induced by the used doses of sodium bicarbonate does not significantly affect micromucosal visualization during double-contrast barium meal.

  9. Metalorganic solution deposition of lead zirconate titanate films onto an additively manufactured Ni-based superalloy

    International Nuclear Information System (INIS)

    Patel, T.; Khassaf, H.; Vijayan, S.; Bassiri-Gharb, N.; Aindow, M.; Alpay, S.P.; Hebert, R.J.

    2017-01-01

    Recent advances in additive manufacturing of high-temperature alloys for structural aerospace applications has led to interest in integrating additional functionality into such parts. Lead zirconate titanate (PZT) is a prototypical ferroelectric ceramic used as the electro-active material in many piezoelectric sensors and actuators. In this study, 300 nm thick PbZr_0_._2Ti_0_._8O_3 (PZT 20/80) films were grown using metalorganic solution deposition onto additively manufactured substrates of Inconel 718. The microstructures of the films and the nature of the film/substrate interfaces were characterized using a combination of X-ray diffraction and electron microscopy techniques. Electrical measurements were performed to determine the ferroelectric, dielectric, and conductive responses of the PZT films. Our findings show that the PZT films exhibit robust ferroelectricity characterized by well-defined polarization-applied electric field (P-E) hysteresis loops. The samples display internal bias of up to ∼40 kV/cm. The room temperature remnant polarization and the small signal dielectric permittivity are ∼70 μC/cm"2 and 205, respectively. The dielectric loss (tan δ) and the leakage current at 1 kHz are 9% and 1 nA at 1 V, respectively. We attribute the internal bias observed in the hysteresis loops and the overall large dielectric losses to the presence of an intermediate oxide layer at the PZT/Inconel interface, which forms during the high temperature crystallization of the ferroelectric film. These results show that it is possible to grow functional oxides with promising electrical properties onto additively manufactured metallic substrates.

  10. Phase stabilisation of hexagonal barium titanate doped with transition metals: A computational study

    International Nuclear Information System (INIS)

    Dawson, J.A.; Freeman, C.L.; Harding, J.H.; Sinclair, D.C.

    2013-01-01

    Interatomic potentials recently developed for the modelling of BaTiO 3 have been used to explore the stabilisation of the hexagonal polymorph of BaTiO 3 by doping with transition metals (namely Mn, Co, Fe and Ni) at the Ti-site. Classical simulations have been completed on both the cubic and hexagonal polymorphs to investigate the energetic consequences of transition metal doping on each polymorph. Ti-site charge compensation mechanisms have been used for the multi-valent transition metal ions and cluster binding energies have been considered. Simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti 2 sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. This energetic difference between the two polymorphs is true for all transition metals tested and all charge states and in the case of tri- and tetra-valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions as observed experimentally. Oxidation during incorporation of Ni 2+ and Fe 3+ ions has also been considered. - Graphical abstract: The representation of the strongest binding energy clusters for tri-valent dopants—(a) Ti 2 /O 1 cluster and (b) Ti 2 /O 2 cluster. Highlights: ► Classical simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti2 sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. ► This energetic difference between the two polymorphs is true for all transition metals tested and all charge states. ► In the case of tri- and tetra- valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions

  11. Adsorption of water-soluble polymers onto barium titanate and its effects 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  13. Synthesis of barium-strontium titanate hollow tubes using Kirkendall effect

    Science.gov (United States)

    Chen, Xuncai; Im, SangHyuk; Kim, Jinsoo; Kim, Woo-Sik

    2018-02-01

    (BaSr)TiO3 hexagonal hollow tubes was fabricated by a solid-state interfacial reaction including a Kirkendall diffusion. Using a co-precipitation and sol-gel process, a core@shell structure of (BaSr)CO3@TiO2 rods were prepared, and then converted to (BaSr)TiO3 hollow tubes at 750 °C. This was a first achievement of single-phase crystal hollow tube. Here, the inner diameter and wall thickness of hollow tube were about 700 nm and 130 nm, respectively. The fabrication of (BaSr)TiO3 hollow tubes was monitored with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to investigate their formation mechanism. The present synthetic approach would provide a new insight into the design and fabrication of hollow architectures of many perovskite oxides.

  14. Barium titanate nanometric polycrystalline ceramics fired by spark plasma sintering.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Ryukhtin, Vasyl; Cinert, Jakub; Lukáč, František

    2016-01-01

    Roč. 42, č. 14 (2016), s. 15989-15993 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G; GA MŠk LM2015056 Institutional support: RVO:61389021 ; RVO:61389005 Keywords : BaTiO3 * Spark plasma sintering * Electrical properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; JH - Ceramics, Fire-Resistant Materials and Glass (UJF-V) Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216311695

  15. Structural and magnetic properties of single-crystalline Co-doped barium titanate nanoparticles

    International Nuclear Information System (INIS)

    Liu Hongxue; Cao Baobao; O'Connor, Charles J.

    2010-01-01

    Undoped and Co-doped BaTiO 3 nanoparticles were synthesized by a one-step sol-precipitation method. For all the samples, X-ray diffraction showed characteristic diffraction lines for BaTiO 3 without the indication of secondary phases. High-resolution transition electron microscopy images showed that BaTiO 3 nanoparticles exhibit the nature of single-crystal. Magnetometry revealed that all the Co-doped BaTiO 3 samples show paramagnetic behaviors and Co ions in BaTiO 3 are present as isolated paramagnetic centers. This is contrasted to several reported cases of ferromagnetism in Co-doped BaTiO 3 .

  16. In-plane microwave dielectric properties of paraelectric barium strontium titanate thin films with anisotropic epitaxy

    Science.gov (United States)

    Simon, W. K.; Akdogan, E. K.; Safari, A.; Bellotti, J. A.

    2005-08-01

    In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25-1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500-150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.

  17. 3D printed barium titanate/poly-(vinylidene fluoride) nano-hybrid with anisotropic dielectric properties

    DEFF Research Database (Denmark)

    Phatharapeetranun, N.; Ksapabutr, B.; Marani, D.

    2017-01-01

    properties of the starting materials are optimized to shape the hybrid by the precision-extrusion-based fuse deposition modeling technique. The 3D-printed BTNFs allow complex shapes with different degrees of fiber alignment as the result of printing shear stress and the chemical composition of the starting...

  18. Plasticizer Effect on Rheological Behaviour of Screen Printing Pastes Based on Barium Titanate Nanopowder

    International Nuclear Information System (INIS)

    Dulina, I; Umerova, S; Ragulya, A

    2015-01-01

    The dependence of rheological behaviour of pastes based on BaTiO 3 nanopowder vs. plasticizer content has been investigated. All pastes prepared for research can be divided into groups by structure types and viscosity. Such a grouping has been explained by different interaction between nanoparticles and binder in the pastes. Particles with molecules of binder form clusters – the representative units in the volume of paste where particles are uniformly distributed. Plasticizer adding effects on binder molecule conformation and change clusters size. Bond strength between clusters can be specified with rheopexy in the area of low shear stress and low strain rates. Rheopexy degree increasing authenticates interaction intensification between clusters. Rheopexy structure destruction leads to separate clusters formation and initiation of the pseudoplastic flow stage. The end of pseudoplastic flow corresponds to structure with clusters assembled into separated layers. Further shear stress increasing leads to inter-clusters bonds appear which can be deformed elastically and the temporary local linkage is possible. Such a phenomenon fully discloses the features of thixotropic structure destruction in plasticized pastes. (paper)

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

    International Nuclear Information System (INIS)

    Shen, Wan

    2010-01-01

    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 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 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 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.)

  20. Synthesis of strontium substituted barium titanate nanoparticles by mechanical alloying and high power ultrasonication destruction

    Energy Technology Data Exchange (ETDEWEB)

    Yustanti, Erlina, E-mail: erlina.yustanti@ui.ac.id [Graduate Program of Material Science, Faculty of Mathematics and Natural Sciences University of Indonesia Jl. Salemba Raya No. 04 Jakarta 10430 (Indonesia); Department of Metallurgy, Faculty of Engineering University of Sultan AgengTirtayasa Jl. Jenderal Sudirman KM 03 Cilegon-Banten 65134 (Indonesia); Hafizah, Mas Ayu Elita, E-mail: kemasayu@yahoo.com; Manaf, Azwar, E-mail: azwar@ui.ac.id [Graduate Program of Material Science, Faculty of Mathematics and Natural Sciences University of Indonesia Jl. Salemba Raya No. 04 Jakarta 10430 (Indonesia)

    2016-04-19

    This paper reports the particle and crystallite size characterizations of mechanically alloyed Ba{sub (1-x)}Sr{sub x}TiO{sub 3} (BST) with x = 0.3 and 0.7 prepared with the assistance of a high-power sonicator. Analytical grade BaCO{sub 3}, TiO{sub 2} and SrCO{sub 3} precursors with a purity of greater than 99 wt.% were mixed and milled using a planetary ball mill to a powder weight ratio of 10:1. Powders obtained after 20 hours of milling time were then sintered at 1200°C for 4 hours to form crystalline powders.These powders were further treated ultrasonically under a fixed 6.7 gr/l particle concentration in demineralized water for 1, 3, 5, 7 hours and a fixed ultrasonic irradiation time of 1 hour to the dispersion of 6.7; 20; 33.3 gr/l concentrations. As to the results of crystallite size characterization, it is demonstrated that the mean crystallite size of BST with x = 0.3 and 0.7 undergo a slight change after the first 1 hour irradiation time and then remain almost unchanged. This was in contrary to the particle size in which the mean particle size of BST with x = 0.3 increased from 765 nm to 1405 nm after 7 hours irradiation time, while that of x = 0.7 increased from 505 nm to 1298 nm after 3 hours and then reduced back to the initial size after 7 hours ultra sonication time. The increase in particle size was due to large of cohesive forces among fine particles. It is also demonstrated that the concentration of particles in a dispersion with anionic surfactant do not effective to reduce the particle sizes ultrasonically. Nanoparticles with the mean size respectively 40 and 10 times larger than their respective crystallite size were successfully obtained respectively in x = 0.3 and x = 0.7.

  1. Real-time observations of interface formation for barium strontium titanate films on silicon

    Science.gov (United States)

    Mueller, A. H.; Suvorova, N. A.; Irene, E. A.; Auciello, O.; Schultz, J. A.

    2002-05-01

    Ba.5Sr.5TiO3 (BST) film growth by ion sputtering on bare and thermally oxidized silicon was observed in real time using in-situ spectroscopic ellipsometry and time of flight ion scattering and recoil spectrometry techniques. At the outset of BST film deposition on silicon, an approximately 30 Å film with intermediate static dielectric constant (K˜12) and refractive index (n˜2.6 at photon energies of 1.5-3.25 eV) interface layer formed on bare silicon. The interface layer growth rate was greatly reduced on an oxidized silicon substrate. The results have profound implications on the static dielectric constant of BST.

  2. Real-time observations of interface formation for barium strontium titanate films on silicon

    International Nuclear Information System (INIS)

    Mueller, A.H.; Suvorova, N.A.; Irene, E.A.; Auciello, O.; Schultz, J.A.

    2002-01-01

    Ba .5 Sr .5 TiO 3 (BST) film growth by ion sputtering on bare and thermally oxidized silicon was observed in real time using in-situ spectroscopic ellipsometry and time of flight ion scattering and recoil spectrometry techniques. At the outset of BST film deposition on silicon, an approximately 30 Aa film with intermediate static dielectric constant (K∼12) and refractive index (n∼2.6 at photon energies of 1.5-3.25 eV) interface layer formed on bare silicon. The interface layer growth rate was greatly reduced on an oxidized silicon substrate. The results have profound implications on the static dielectric constant of BST

  3. Characteristics of the surface layer of barium strontium titanate thin films deposited by laser ablation

    International Nuclear Information System (INIS)

    Craciun, V.; Singh, R. K.

    2000-01-01

    Ba 0.5 Sr 0.5 TiO 3 (BST) thin films grown on Si by an in situ ultraviolet-assisted pulsed laser deposition (UVPLD) technique exhibited significantly higher dielectric constant and refractive index values and lower leakage current densities than films grown by conventional PLD under similar conditions. X-ray photoelectron spectroscopy (XPS) investigations have shown that the surface layer of the grown films contained, besides the usual BST perovskite phase, an additional phase with Ba atoms in a different chemical state. PLD grown films always exhibited larger amounts of this phase, which was homogeneously mixed with the BST phase up to several nm depth, while UVPLD grown films exhibited a much thinner (∼1 nm) and continuous layer. The relative fraction of this phase was not correlated with the amount of C atoms present on the surface. Fourier transform infrared spectroscopy did not find any BaCO 3 contamination layer, which was believed to be related to this new phase. X-ray diffraction measurement showed that although PLD grown films contained less oxygen atoms, the lattice parameter was closer to the bulk value than that of UVPLD grown films. After 4 keV Ar ion sputtering for 6 min, XPS analysis revealed a small suboxide Ba peak for the PLD grown films. This finding indicates that the average Ba-O bonds are weaker in these films, likely due to the presence of oxygen vacancies. It is suggested here that this new Ba phase corresponds to a relaxed BST surface layer. (c) 2000 American Institute of Physics

  4. Characteristics of the surface layer of barium strontium titanate thin films deposited by laser ablation

    Science.gov (United States)

    Craciun, V.; Singh, R. K.

    2000-04-01

    Ba0.5Sr0.5TiO3 (BST) thin films grown on Si by an in situ ultraviolet-assisted pulsed laser deposition (UVPLD) technique exhibited significantly higher dielectric constant and refractive index values and lower leakage current densities than films grown by conventional PLD under similar conditions. X-ray photoelectron spectroscopy (XPS) investigations have shown that the surface layer of the grown films contained, besides the usual BST perovskite phase, an additional phase with Ba atoms in a different chemical state. PLD grown films always exhibited larger amounts of this phase, which was homogeneously mixed with the BST phase up to several nm depth, while UVPLD grown films exhibited a much thinner (˜1 nm) and continuous layer. The relative fraction of this phase was not correlated with the amount of C atoms present on the surface. Fourier transform infrared spectroscopy did not find any BaCO3 contamination layer, which was believed to be related to this new phase. X-ray diffraction measurement showed that although PLD grown films contained less oxygen atoms, the lattice parameter was closer to the bulk value than that of UVPLD grown films. After 4 keV Ar ion sputtering for 6 min, XPS analysis revealed a small suboxide Ba peak for the PLD grown films. This finding indicates that the average Ba-O bonds are weaker in these films, likely due to the presence of oxygen vacancies. It is suggested here that this new Ba phase corresponds to a relaxed BST surface layer.

  5. One-dimensional carbon nanotube@barium titanate@polyaniline multiheterostructures for microwave absorbing application

    Science.gov (United States)

    Ni, Qing-Qing; Zhu, Yao-Feng; Yu, Lu-Jun; Fu, Ya-Qin

    2015-04-01

    Multiple-phase nanocomposites filled with carbon nanotubes (CNTs) have been developed for their significant potential in microwave attenuation. The introduction of other phases onto the CNTs to achieve CNT-based heterostructures has been proposed to obtain absorbing materials with enhanced microwave absorption properties and broadband frequency due to their different loss mechanisms. The existence of polyaniline (PANI) as a coating with controllable electrical conductivity can lead to well-matched impedance. In this work, a one-dimensional CNT@BaTiO3@PANI heterostructure composite was fabricated. The fabrication processes involved coating of an acid-modified CNT with BaTiO3 (CNT@BaTiO3) through a sol-gel technique followed by combustion and the formation of CNT@BaTiO3@PANI nanohybrids by in situ polymerization of an aniline monomer in the presence of CNT@BaTiO3, using ammonium persulfate as an oxidant and HCl as a dopant. The as-synthesized CNT@BaTiO3@PANI composites with heterostructures were confirmed by various morphological and structural characterization techniques, as well as conductivity and microwave absorption properties. The measured electromagnetic parameters showed that the CNT@BaTiO3@PANI composites exhibited excellent microwave absorption properties. The minimum reflection loss of the CNT@BaTiO3@PANI composites with 20 wt % loadings in paraffin wax reached -28.9 dB (approximately 99.87% absorption) at 10.7 GHz with a thickness of 3 mm, and a frequency bandwidth less than -20 dB was achieved from 10 to 15 GHz. This work demonstrated that the CNT@BaTiO3@PANI heterostructure composite can be potentially useful in electromagnetic stealth materials, sensors, and electronic devices.

  6. Effect of splat morphology on the microstructure and dielectric properties of plasma sprayed barium titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Pakseresht, A.H., E-mail: amirh_pak@yahoo.com [Center of Ceramic Coatings, Department of Ceramics, Materials and Energy Research Center, PO Box 31787-316, Karaj (Iran, Islamic Republic of); Rahimipour, M.R. [Center of Ceramic Coatings, Department of Ceramics, Materials and Energy Research Center, PO Box 31787-316, Karaj (Iran, Islamic Republic of); Vaezi, M.R. [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, PO Box 31787-316, Karaj (Iran, Islamic Republic of); Salehi, M. [Department of Materials Engineering, Isfahan University of Technology, PO Box 84156-83111, Isfahan (Iran, Islamic Republic of)

    2015-01-01

    Highlights: • BaTiO{sub 3} splats were collected on the mirror polished substrate for the first time. • There was no amorphous phase in the coating collected on the preheated substrate. • The dielectric coefficient was increased by a factor of 3 for the coatings sprayed on the preheated substrates. - Abstract: In the thermal spray process, the film is built up by impingement of molten droplets onto substrate. Splats are created by flattening and spreading of the impacting droplets. Splat morphology can determine the microstructure, physical and mechanical properties of the coating. In this study, BaTiO{sub 3} films were deposited onto a mirror polished stainless steel substrates kept at three different temperatures (25, 300 and 600 °C). At the elevated temperatures, the substrate surface topography and the desorbtion of adsorbates and condensate at the substrate surface are two important factors which change the morphology of the individual splats, from splash morphology to disk-like shape. Splat morphology can determine deposit microstructure and improve the coating properties. The morphology of individual splats and the films were studied using scanning electron microscopy. Phase formation of the films was analyzed by X-ray diffraction. The surface topography of the substrates with different temperatures was analyzed using atomic force microscopy. Furthermore, X-ray photoelectron spectroscopy was performed to determine the chemical compositions of the surface substrate. Results indicated that the porosity in the film produced at room temperature was higher than that in the film deposited on the heated substrates. Also, the dielectric coefficient of the films was increased by decreasing the common defects from 120 to 505 for film deposited on as-received and heated substrates, respectively.

  7. 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.

  8. 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.

  9. 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.

  10. Microwave heating behavior and microwave absorption properties of barium titanate at high temperatures

    Directory of Open Access Journals (Sweden)

    K. Kashimura

    2016-06-01

    Full Text Available The temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated over various frequencies and temperatures of 25-1000 ∘C. First, using both the coaxial transmission line method and the cavity perturbation method by a network analyzer, the real and imaginary parts of the relative permittivity of BaTiO3 ( ε r ′ and ε r ″ , respectively were measured, in order to improve the reliability of the data obtained at 2.45 GHz. The imaginary parts of the relative permittivity as measured by the two methods were explored by their heating behaviors. Furthermore, the temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated for frequencies of 2.0-13.5 GHz and temperatures of 25-1000 ∘C using the coaxial transmission line method.

  11. 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.

  12. Nanostructured barium titanate thin films from nanoparticles obtained by an emulsion precipitation method

    NARCIS (Netherlands)

    Woudenberg, F.C.M.; Sager, W.F.C.; ten Elshof, Johan E.; Verweij, H.

    2005-01-01

    Spherical non-agglomerated BaTiO3 precursor particles of 3–5 nm size were prepared by an emulsion precipitation method that consisted of the complexation of Ba- and Ti-precursors in separate water-in-decane emulsions, followed by mixing and controlled precipitation upon reactive decomposition of

  13. Electrical characterization and impedance response of lanthanum doped barium titanate ceramics

    Directory of Open Access Journals (Sweden)

    Mančić D.

    2008-01-01

    Full Text Available The dielectric permittivity and dissipation factor of La-doped and undoped BaTiO3 were investigated as a function of frequency and temperature. The impedance response was used to study the electrical properties of La-doped BaTiO3 over the temperature range from room temperature (RT to 350°C. La-doped and undoped BaTiO3, obtained by a modified Pechini method, were sintered in air at 1300°C for 2 and 16 hours. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE. The most suitable electrical circuit for the interpretation of experimental results is found to be the equivalent circuit consisting of resistors and CPE elements which replace the capacitor elements. The contribution of grain boundary resistance to the total resistance of a system is remarkable at low temperature. Dielectric permittivity of doped BaTiO3 was in the range of 8000 to 12000 at 1 kHz and the dissipation factor was less than 1%.

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

    International Nuclear Information System (INIS)

    Razak, K.A.; Asadov, A.; Yoo, J.; Haemmerle, E.; Gao, W.

    2008-01-01

    The preparation procedure, structural and dielectric properties of hydrothermally derived Ba x Sr 1-x TiO 3 (BST) were studied. BST with initial Ba compositions of 75, 80, 85 and 90 mol.% were prepared by a high temperature hydrothermal synthesis. The obtained powders were pressed into pellet, cold isostatically pressed and sintered at 1200 deg. C for 3 hours. The phase compositions and lattice parameters of the as prepared powders and sintered samples were analysed using X-ray diffractometry. A fitting software was used to analyse the XRD spectra to separate different phases. It was found that BST powder produced by the high temperature hydrothermal possessed a two-phase structure. This structure became more homogeneous during sintering due to interdiffusion but a small amount of minor phase can still be traced. Samples underwent an abnormal grain growth, whereby some grains grow faster than the other due to the presence of two-phase structure. The grain size increased with increasing Ba amount. Dielectric constant and polarisation increased with increasing Ba content but it was also affected by the electronic state and grain size of the compositions

  15. 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.)

  16. Dielectric Properties of Sol-Gel Derived Barium Strontium Titanate and Microwave Sintering of Ceramics

    Science.gov (United States)

    Selmi, Fathi A.

    This thesis consists of two areas of research: (1) sol-gel processing of Ba_{rm 1-x}Sr_{rm x} TiO_3 ceramics and their dielectric properties measurement; and (2) microwave versus conventional sintering of ceramics such as Al_2 O_3, Ba_{ rm 1-x}Sr_{rm x}TiO_3, Sb-doped SnO _2 and YBa_2Cu _3O_7. Sol-gel powders of BaTiO_3, SrTiO_3, and their solid solutions were synthesized by the hydrolysis of titanium isopropoxide and Ba and Sr methoxyethoxides. The loss tangent and dielectric constant of both sol-gel and conventionally prepared and sintered Ba_{rm 1-x}Sr _{rm x}TiO _3 ceramics were investigated at high frequencies. The sol-gel prepared ceramics showed higher dielectric constant and lower loss compared to those prepared conventionally. Ba _{rm 1-x}Sr _{rm x}TiO_3 ceramics were tunable with applied bias, indicating the potential use of this material for phase shifter applications. Porous Ba_{0.65}Sr _{0.35}TiO_3 was also investigated to lower the dielectric constant. Microwave sintering of alpha -Al_2O_3 and SrTiO_3 was investigated using an ordinary kitchen microwave oven (2.45 GHz; 600 Watts). The use of microwaves with good insulation of alpha -Al_2O_3 and SrTiO_3 samples resulted in their rapid sintering with good final densities of 96 and 98% of the theoretical density, respectively. A comparison of grain size for conventionally and microwave sintered SrTiO_3 samples did not show a noticeable difference. However, the grain size of microwave sintered alpha-Al_2O _3 was found to be larger than that of conventionally sintered sample. These results show that rapid sintering of ceramics can be achieved by using microwave radiation. The sintering behavior of coprecipitated Sb-doped SnO_2 was investigated using microwave power absorption. With microwave power, samples were sintered at 1450^circC for 20 minutes and showed a density as high as 99.9% of theoretical. However, samples fired in a conventional electric furnace at the same temperature for 4 hours showed only 60% of theoretical density. Microwave sintering also led to improvement in terms of uniform structure and electrical properties. Ba_{0.65}Sr _{0.35}TiO_3 was sintered using the microwave power at 1300 ^circC for 10 minutes. A density of 99% was achieved with small and uniform grain size. Superconducting powders have been successfully prepared by the sol-gel process and sintered and annealed using microwave power. Sintering and densification was achieved in a shorter time with microwave heating than with conventional heating and microwave heating appears to result in refined microstructure.

  17. Microstructure evolution and phase transition in La/Mn doped barium titanate ceramics

    Directory of Open Access Journals (Sweden)

    Vesna Paunović

    2010-12-01

    Full Text Available La/Mn codoped BaTiO3 with different La2O3 content, ranging from 0.1 to 5.0 at% La, was investigated regarding their microstructural and dielectric characteristics. The content of 0.05 at% Mn was constant in all investigated samples. The samples were sintered at 1320°C and 1350°C for two hours. Microstructural studies were done using SEM and EDS analysis. The fine-grained microstructure was obtained even for low content of La. The appearance of secondary abnormal grains with serrated features along grain boundaries was observed in 1.0 at% La-BaTiO3 sintered at 1350°C. Nearly flat permittivity-temperature response was obtained in specimens with 2.0 and 5.0 at% La. Using the modified Curie-Weiss law a critical exponent γ and C’were calculated. The obtained values of γ pointed out the diffuse phase transformation in heavily doped BaTiO3 and great departure from the Curie-Weiss law for low doped ceramics.

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

    International Nuclear Information System (INIS)

    Wang Jingyang; Zhang Tianjin; Pan Ruikun; Ma Zhijun; Wang Jinzhao

    2012-01-01

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

  19. Grain size and boundary-related effects on the properties of nanocrystalline barium titanate ceramics

    Czech Academy of Sciences Publication Activity Database

    Buscaglia, V.; Buscaglia, M. T.; Viviani, M.; Mitoseriu, L.; Nanni, P.; Trefiletti, V.; Piaggio, P.; Gregora, Ivan; Ostapchuk, Tetyana; Pokorný, Jan; Petzelt, Jan

    2006-01-01

    Roč. 26, - (2006), s. 2889-2898 ISSN 0955-2219 R&D Projects: GA MŠk OC 525.20 Institutional research plan: CEZ:AV0Z10100520 Keywords : grain size * grain boundaries * spectroscopy * dielectric properties * BaTiO 3 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.576, year: 2006

  20. Synthesis of strontium substituted barium titanate nanoparticles by mechanical alloying and high power ultrasonication destruction

    International Nuclear Information System (INIS)

    Yustanti, Erlina; Hafizah, Mas Ayu Elita; Manaf, Azwar

    2016-01-01

    This paper reports the particle and crystallite size characterizations of mechanically alloyed Ba (1-x) Sr x TiO 3 (BST) with x = 0.3 and 0.7 prepared with the assistance of a high-power sonicator. Analytical grade BaCO 3 , TiO 2 and SrCO 3 precursors with a purity of greater than 99 wt.% were mixed and milled using a planetary ball mill to a powder weight ratio of 10:1. Powders obtained after 20 hours of milling time were then sintered at 1200°C for 4 hours to form crystalline powders.These powders were further treated ultrasonically under a fixed 6.7 gr/l particle concentration in demineralized water for 1, 3, 5, 7 hours and a fixed ultrasonic irradiation time of 1 hour to the dispersion of 6.7; 20; 33.3 gr/l concentrations. As to the results of crystallite size characterization, it is demonstrated that the mean crystallite size of BST with x = 0.3 and 0.7 undergo a slight change after the first 1 hour irradiation time and then remain almost unchanged. This was in contrary to the particle size in which the mean particle size of BST with x = 0.3 increased from 765 nm to 1405 nm after 7 hours irradiation time, while that of x = 0.7 increased from 505 nm to 1298 nm after 3 hours and then reduced back to the initial size after 7 hours ultra sonication time. The increase in particle size was due to large of cohesive forces among fine particles. It is also demonstrated that the concentration of particles in a dispersion with anionic surfactant do not effective to reduce the particle sizes ultrasonically. Nanoparticles with the mean size respectively 40 and 10 times larger than their respective crystallite size were successfully obtained respectively in x = 0.3 and x = 0.7.

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

    NARCIS (Netherlands)

    Tiggelman, M.P.J.

    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,

  2. Pyroelectric and dielectric properties of lead-free ferroelectric Ba3Nb2O8 ceramic

    International Nuclear Information System (INIS)

    Pati, Biswajit; Choudhary, R.N.P.; Das, Piyush R.; Parida, B.N.; Padhee, R.

    2014-01-01

    Graphical abstract: - Highlights: • Barium orthoniobate (lead-free perovskite) crystallizes as palmierite with structural stability. • The material exhibits ferroelectric phase transition of diffuse-type suitable for devices. • The low values of ε r and tan δ at high frequencies makes it a potential candidate for microwave applications. • The material has very good pyroelectric properties for detector application. • The material exhibits smaller value of dc activation energy. - Abstract: The present study highlights ferroelectric phase transition, dielectric, pyroelectric properties and conduction mechanism of highly crystallized barium orthoniobate (Ba 3 Nb 2 O 8 ) ceramic, prepared by a solid-state reaction technique. X-ray diffraction studies show the formation of a single-phase compound in hexagonal crystal system. Detailed studies of dielectric parameters (ε r and tan δ) of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. An anomaly in ε r suggests the possible existence of a ferroelectric–paraelectric phase transition of diffuse-type in the material. The low dielectric loss and moderate relative permittivity make this material (with certain modification) a potential candidate for microwave applications. Studies of pyroelectric properties reveal that the materials have reasonably high figure of merit useful for fabrication of pyroelectric detectors. The low-leakage current and negative temperature coefficient of resistance (NTCR) behavior of the sample have been verified from J–E plots. The nature of variation of dc conductivity with temperature confirms the Arrhenius and NTCR behavior of the material

  3. Enterogastroesophageal reflux during barium enema: Report of a case

    International Nuclear Information System (INIS)

    Shin, Hyoun Ja; Rhee, Hak Song

    1972-01-01

    Enterogastric reflux during barium enema examination has been ascribed to various causes including incompetence of the ilepcecal valve, shunt, fistula, excessive barium etc. Recently we have encountered a case of complete enterogastroesphageal regurgitation during barium enema examination performed for the reduction of the ileocolic intuosusception in 6 months old baby. The regurgitation occurred only in the first of two barium enema examinations conducted at one month interval for recurring intussusception. The barium-saline solution used in the present study was not more than 350 ml in quantity. No organic or physical causes of such a complete regurgitation could be determined

  4. Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

    Science.gov (United States)

    2016-04-19

    the free energy of the system [3,4,8]. Intensive research has been aimed at bypassing the intrinsic size limits imposed by the depolarization field...Page 1 of 21   Ultrafast photovoltaic response in ferroelectric nanolayers Dan Daranciang1,2, Matthew J. Highland3, Haidan Wen4, Steve M. Young5...ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on

  5. Ferroelectric Phase Diagram of PVDF:PMMA

    OpenAIRE

    Li, Mengyuan; Stingelin, Natalie; Michels, Jasper J.; Spijkman, Mark-Jan; Asadi, Kamal; Feldman, Kirill; Blom, Paul W. M.; de Leeuw, Dago M.

    2012-01-01

    We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of alpha- and beta-phase PVDF was identified. Ferroelectric beta-PVDF:PMMA blend films were made by melting, ice quenching, and subsequent annealing above the glass transition temperature of PMMA, close to the melting temperature of PVDF. Addition of PMMA suppresses the crystallizatio...

  6. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... China AGENCY: United States International Trade Commission. ACTION: Notice of Commission determination... China. SUMMARY: The Commission hereby gives notice that it will proceed with a full review pursuant to... antidumping duty order on barium chloride from China would be likely to lead to continuation or recurrence of...

  7. Blood pressure changes during barium enema

    International Nuclear Information System (INIS)

    Roach, S.C.; Martin, O.J.D.; Owen, A.; Martin, D.F.

    2001-01-01

    AIMS: To document blood pressure changes during barium enema examination and to determine at what point in the examination changes are likely to occur. METHODS AND RESULTS: Blood pressure measurements were taken at seven points during the course of barium enema examination in 107 consecutive patients. We found that patients over the age of 60 years had statistically significant decreases in blood pressure when they were stood up during the course of the examination. Many of these patients were asymptomatic. Patients who had symptoms (15/107, 14%) when standing up had a degree of hypotension. The duration of barium enema examination is longer in those patients who experience symptoms. CONCLUSION: During a barium enema examination hypotension occurs at the point of standing up more frequently in patients over 60 years and in those who suffer symptoms at this time. Patients who fall into one of these groups should be considered at risk of fainting at this point in the examination. A modified technique to avoid standing should be considered in at-risk patients. Roach, S.C. et al. (2001)

  8. High temperature impedance spectroscopy of barium stannate ...

    Indian Academy of Sciences (India)

    (M = Ba, Sr, Ca and Pb). ... Barium stannate (BaSnO3) is a cubic pervoskite oxide com- .... were gold-sputtered and scanned in different regions using .... de ions. Water insertion into the oxide structure can be re- presented as the process of ...

  9. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-149 (Third Review)] 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: Amy Sherman (202-205-3289...

  10. 75 FR 33824 - Barium Chloride From China

    Science.gov (United States)

    2010-06-15

    ... China Determination On the basis of the record\\1\\ developed in the subject five-year review, the United... China would be likely to lead to continuation or recurrence of material injury to an industry in the... contained in USITC Publication 4157 (June 2010), entitled Barium Chloride from China: Investigation No. 731...

  11. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  12. Rheological properties of potassium barium borate glasses

    NARCIS (Netherlands)

    Szwejda, K.A.; Vogel, D.L.; Stevels, J.M.

    1973-01-01

    Several series of potassium barium borate glasses have been investigated as to their rheological properties. It has been found, that all these glasses show deviations from ‘Newtonian’ behaviour below temperatures corresponding to viscosities of 1010 poises. The activation energies of viscous flow

  13. Amino acidis derived from Titan tholins

    Science.gov (United States)

    Khare, Bishun N.; Sagan, Carl; Ogino, Hiroshi; Nagy, Bartholomew; Er, Cevat

    1986-01-01

    The production of amino acids by acid treatment of Titan tholin is experimentally investigated. The synthesis of Titan tholin and the derivatization of amino acids to N-trifluoroacetyl isopropyl esters are described. The gas chromatography/mass spectroscopy analysis of the Titan tholins reveals the presence of glycine, alpha and beta alainine, and aspartic acid, and the total yield of amino acids is about 0.01.

  14. Kinetic approach to the explanation of fatigue effect in ferroelectric materials

    International Nuclear Information System (INIS)

    Shur, V.Ya.; Rumyantsev, E.L.; Nikolaeva, E.V.; Shishkin, E.I.; Baturin, I.S.

    2002-01-01

    The new kinetic approach to explanation of the fatigue effect in the ferroelectrics consistent change in the area and geometry of the switched-over part of the sample by the cyclic switch-over, accompanied by the origination and growth of the kinetic frozen domains, is considered. It is supposed, that the fatigue effect is conditioned by the self-organizing formation of the spatially nonuniform internal shift field due to the delay of the voluminous scanning of the depolarizing field. The changes in the value of the switched charge and the switch-over current amplitude, calculated through the computerized simulation of the domains kinetics by the cyclic switch-over are in good agreement with the experimental data, obtained in thin films of the lead zirconate-titanate [ru

  15. Thermally-treated Pt-coated silicon AFM tips for wear resistance in ferroelectric data storage

    International Nuclear Information System (INIS)

    Bhushan, Bharat; Palacio, Manuel; Kwak, Kwang Joo

    2008-01-01

    In ferroelectric data storage, a conductive atomic force microscopy (AFM) probe with a noble metal coating is placed in contact with a lead zirconate titanate (PZT) film. The understanding and improvement of probe tip wear, particularly at high velocities, is needed for high data rate recording. A commercial Pt-coated silicon AFM probe was thermally treated in order to form platinum silicide at the near-surface. Nanoindentation, nanoscratch and wear experiments were performed to evaluate the mechanical properties and wear performance at high velocities. The thermally treated tip exhibited lower wear than the untreated tip. The tip wear mechanism is adhesive and abrasive wear with some evidence of impact wear. The enhancement in mechanical properties and wear resistance in the thermally treated film is attributed to silicide formation in the near-surface. Auger electron spectroscopy and electrical resistivity measurements confirm the formation of platinum silicide. This study advances the understanding of thin film nanoscale surface interactions

  16. Enhanced ferroelectric and piezoelectric properties in La-modified PZT ceramics

    Science.gov (United States)

    Kour, P.; Pradhan, S. K.; Kumar, Pawan; Sinha, S. K.; Kar, Manoranjan

    2016-06-01

    The effect of lanthanum (La) doping on ferroelectric and piezoelectric properties of lead zirconate titanate (PZT) sample has been investigated. Pb1- x La x Zr0.52Ti0.48O3 ceramics with x = 0.00, 0.02, 0.04, 0.06 and 0.10 were prepared by the sol-gel technique. Raman and Fourier transforms infrared spectroscopy have been employed to understand the structural modification due to ionic size mismatch. Raman spectra show the existence of both rhombohedral and tetragonal crystal symmetries. It also shows the dielectric relaxation with increase in La concentration in the sample. The increase in lattice strain due to La doping increases the remnant polarization and coercive field. The linear piezoelectric coefficient increases with the increase in La concentration. It reveals that La-substituted PZT is a better candidate for piezoelectric sensor applications as compared to that of PZT.

  17. Dielectric characteristics of PZT 95/5 ferroelectric ceramics at high pressures

    International Nuclear Information System (INIS)

    Spears, R.K.

    1978-01-01

    The room temperature dielectric properties of a ferroelectric ceramic having a nominal composition of 95 atomic percent lead zirconate and 5 atomic percent lead titanate (designated as PZT 95/5) with a niobium dopant were examined at high hydrostatic pressures using a tetrahedral anvil apparatus. This ceramic has practical applications as a power source in which large quantities of charge are released by dynamic (shock wave) depolarization. Numerous mathematical models of this process have been proposed; however, the use of models has been limited because of the lack of high pressure electrical properties. This study attempted to provide these data on PZT 95/5 by determining the small signal and high electric field dielectric properties at pressures over 4 GPa

  18. Titan Montgolfiere Buoyancy Modulation System, Phase I

    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...

  19. Titan's geoid and hydrology: implications for Titan's geological evolution

    Science.gov (United States)

    Sotin, Christophe; Seignovert, Benoit; Lawrence, Kenneth; MacKenzie, Shannon; Barnes, Jason; Brown, Robert

    2014-05-01

    A 1x1 degree altitude map of Titan is constructed from the degree 4 gravity potential [1] and Titan's shape [2] determined by the Radio Science measurements and RADAR observations of the Cassini mission. The amplitude of the latitudinal altitude variations is equal to 300 m compared to 600 m for the amplitude of the latitudinal shape variations. The two polar caps form marked depressions with an abrupt change in topography at exactly 60 degrees at both caps. Three models are envisaged to explain the low altitude of the polar caps: (i) thinner ice crust due to higher heat flux at the poles, (ii) fossil shape acquired if Titan had higher spin rate in the past, and (iii) subsidence of the crust following the formation of a denser layer of clathrates as ethane rain reacts with the H2O ice crust [3]. The later model is favored because of the strong correlation between the location of the cloud system during the winter season and the latitude of the abrupt change in altitude. Low altitude polar caps would be the place where liquids would run to and eventually form large seas. Indeed, the large seas of Titan are found at the deepest locations at the North Pole. However, the lakes and terrains considered to be evaporite candidates due to their spectral characteristics in the infrared [4,5] seem to be perched. Lakes may have been filled during Titan's winter and then slowly evaporated leaving material on the surface. Interestingly, the largest evaporite deposits are located at the equator in a deep depression 150 m below the altitude of the northern seas. This observation seems to rule out the presence of a global subsurface hydrocarbon reservoir unless the evaporation rate at the equator is faster than the transport of fluids from the North Pole to the equator. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Iess L. et al. (2012) Science, doi 10.1126/science.1219631. [2] Lorenz R.D. (2013

  20. Titan from Cassini-Huygens

    CERN Document Server

    Brown, Robert H; Waite, J. Hunter

    2010-01-01

    This book reviews our current knowledge of Saturn's largest moon Titan featuring the latest results obtained by the Cassini-Huygens mission. A global author team addresses Titan’s origin and evolution, internal structure, surface geology, the atmosphere and ionosphere as well as magnetospheric interactions. The book closes with an outlook beyond the Cassini-Huygens mission. Colorfully illustrated, this book will serve as a reference to researchers as well as an introduction for students.

  1. Thermal stability of titanate nanotubes

    Czech Academy of Sciences Publication Activity Database

    Králová, Daniela; Kužel, R.; Kovářová, Jana; Dybal, Jiří; Šlouf, Miroslav

    2009-01-01

    Roč. 16, 2a (2009), s. 41-43 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN200520704 Institutional research plan: CEZ:AV0Z40500505 Keywords : titanate nanotubes * thermal stability Subject RIV: CD - Macromolecular Chemistry

  2. Dielectric response and pyroelectric properties of lead-free ferroelectric Ba3(VO42

    Directory of Open Access Journals (Sweden)

    Biswajit Pati

    2015-03-01

    Full Text Available The current paper presents results of dielectric response, pyroelectric behavior and conductivity study of lead-free ferroelectric barium orthovanadate (Ba3(VO42 or Ba3V2O8 ceramic, for a wide range of temperature and frequency. An X-ray diffraction study suggests the formation of a single-phase compound in trigonal crystal system. The SEM micrograph of gold-coated pellet sample shows well-defined and homogeneous morphology. Detailed studies of dielectric parameters (εr and tan δ of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. The nature of Polarization versus electric field (P–E hysteresis loop of Ba3V2O8 at room temperature suggests its ferroelectric nature. The temperature dependence of pyroelectric coefficient and figure of merits of the sample support its dielectric response. The nature of variation of dc conductivity with temperature confirms the Arrhenius and negative temperature coefficient of resistance (NTCR behavior of the material.

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

    International Nuclear Information System (INIS)

    Fernandes, J.P.; Duarte, G.W.; Caldart, C.; Kniess, C.T.; Montedo, O.R.K.; Rocha, M.R.; Riella, H.G.; Fiori, M.A.

    2015-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-15

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

  5. 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

  6. Dimensional scaling of perovskite ferroelectric thin films

    Science.gov (United States)

    Keech, Ryan R.

    Dimensional size reduction has been the cornerstone of the exponential improvement in silicon based logic devices for decades. However, fundamental limits in the device physics were reached ˜2003, halting further reductions in clock speed without significant penalties in power consumption. This has motivated the research into next generation transistors and switching devices to reinstate the scaling laws for clock speed. This dissertation aims to support the scaling of devices that are based on ferroelectricity and piezoelectricity and to provide a roadmap for the corresponding materials performance. First, a scalable growth process to obtain highly {001}-oriented lead magnesium niobate - lead titanate (PMN-PT) thin films was developed, motivated by the high piezoelectric responses observed in bulk single crystals. It was found that deposition of a 2-3 nm thick PbO buffer layer on {111} Pt thin film bottom electrodes, prior to chemical solution deposition of PMN-PT reduces the driving force for Pb diffusion from the PMN-PT to the bottom electrode, and facilitates nucleation of {001}-oriented perovskite grains. Energy dispersive spectroscopy demonstrated that up to 10% of the Pb from a PMN-PT precursor solution may diffuse into the bottom electrode. PMN-PT grains with a mixed {101}/{111} orientation in a matrix of Pb-deficient pyrochlore phase were then promoted near the interface. When this is prevented, phase pure films with {001} orientation with Lotgering factors of 0.98-1.0, can be achieved. The resulting films of only 300 nm in thickness exhibit longitudinal effective d33,f coefficients of ˜90 pm/V and strain values of ˜1% prior to breakdown. 300 nm thick epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) blanket thin films were studied for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO3, while

  7. Enlarging photovoltaic effect: combination of classic photoelectric and ferroelectric photovoltaic effects.

    Science.gov (United States)

    Zhang, Jingjiao; Su, Xiaodong; Shen, Mingrong; Dai, Zhihua; Zhang, Lingjun; He, Xiyun; Cheng, Wenxiu; Cao, Mengyu; Zou, Guifu

    2013-01-01

    Converting light energy to electrical energy in photovoltaic devices relies on the photogenerated electrons and holes separated by the built-in potential in semiconductors. Photo-excited electrons in metal electrodes are usually not considered in this process. Here, we report an enhanced photovoltaic effect in the ferroelectric lanthanum-modified lead zirconate titanate (PLZT) by using low work function metals as the electrodes. We believe that electrons in the metal with low work function could be photo-emitted into PLZT and form the dominant photocurrent in our devices. Under AM1.5 (100 mW/cm²) illumination, the short-circuit current and open-circuit voltage of Mg/PLZT/ITO are about 150 and 2 times of those of Pt/PLZT/ITO, respectively. The photovoltaic response of PLZT capacitor was expanded from ultraviolet to visible spectra, and it may have important impact on design and fabrication of high performance photovoltaic devices based on ferroelectric materials.

  8. Photostriction and elasto-optic response in multiferroics and ferroelectrics from first principles

    Science.gov (United States)

    Yang, Yurong; Paillard, Charles; Xu, Bin; Bellaiche, L.

    2018-02-01

    The present work reviews a series of recent first-principles studies devoted to the description of the interaction of light and strain in ferroelectric and multiferroic materials. Specifically, the modelling schemes used in these works to describe the so-called photostriction and elasto-optic effects are presented, in addition to the results and analysis provided by these ab initio calculations. In particular, the large importance of the piezoelectric effect in the polar direction in the photostriction of ferroelectric materials is stressed. Similarly, the occurrence of low-symmetry phases in lead titanate thin films under tensile strain is demonstrated to result in large elasto-optic constants. In addition, first-principle calculations allow to gain microscopic knowledge of subtle effects, for instance in the case of photostriction, where the deformation potential effect in directions perpendicular to the polar axis is shown to be almost as significant as the piezoelectric effect. As a result, the numerical methods presented here could propel the design of efficient opto-mechanical devices.

  9. Evaluation of Data Retention Characteristics for Ferroelectric Random Access Memories (FRAMs)

    Science.gov (United States)

    Sharma, Ashok K.; Teverovsky, Alexander

    2001-01-01

    Data retention and fatigue characteristics of 64 Kb lead zirconate titanate (PZT)-based Ferroelectric Random Access Memories (FRAMs) microcircuits manufactured by Ramtron were examined over temperature range from -85 C to +310 C for ceramic packaged parts and from -85 C to +175 C for plastic parts, during retention periods up to several thousand hours. Intrinsic failures, which were caused by a thermal degradation of the ferroelectric cells, occurred in ceramic parts after tens or hundreds hours of aging at temperatures above 200 C. The activation energy of the retention test failures was 1.05 eV and the extrapolated mean-time-to-failure (MTTF) at room temperature was estimated to be more than 280 years. Multiple write-read cycling (up to 3x10(exp 7)) during the fatigue testing of plastic and ceramic parts did not result in any parametric or functional failures. However, operational currents linearly decreased with the logarithm of number of cycles thus indicating fatigue process in PZT films. Plastic parts, that had more recent date code as compared to ceramic parts, appeared to be using die with improved process technology and showed significantly smaller changes in operational currents and data access times.

  10. Oesophageal motility disorders - diagnosis with a barium-rice study

    International Nuclear Information System (INIS)

    Schwickert, H.C.; Schadmand-Fischer, S.; Klose, P.; Staritz, M.; Ueberschaer, B.; Thelen, M.

    1993-01-01

    The purpose of this study was to evaluate the role of a 'barium-rice' study for diagnosis of dysphagia and oesophageal motility disorders. Material and methods: 203 patients with oesophageal motility disorders of various aetiologies were examined by both conventional barium study and a 'barium-rice' study. During the latter, oesophageal clearance of a defined mixture of barium sulfate and boiled rice was measured. Results: The conventional barium study revealed prolonged transit time in only 15.8% (32 of 203 cases), whereas barium-rice study was pathological in 50.8% (103 of 203 cases). In 71 of 171 patients (41.5%) with a normal barium study, barium-rice passage was prolonged. In 23 patients, radiological results were confirmed by manometric measurements. Conclusion: Oesophageal motility disorders are detected by a barim-rice study with high sensitivity independent of the underlying disease. The barium-rice study offers a simple diagnostic tool revealing quantitative and reliable results. The barium-rice study is a suitable method for screening and follow-up of patients with dysphagia and oesophageal motility disorders. (orig.) [de

  11. Anelastic deformation of Pb(Zr,Ti)O3 thin films by non-180 deg. ferroelectric domain wall movements during nanoindentation

    International Nuclear Information System (INIS)

    Alguero, M.; Bushby, A.J.; Reece, M.J.; Seifert, A.

    2002-01-01

    Lead zirconate titanate Pb(Zr,Ti)O 3 ferroelectric thin films show significant anelastic deformation when indented with spherical tipped indenters. Experiments on films with different Zr/Ti ratio and a mixed , preferred crystallographic orientation have shown that there is a good agreement between the anelastic deformation and the maximum strain achievable by non-180 deg. domain wall movement. An expected increase of the indentation stiffness of the films also accompanies the anelastic deformation because of the single crystal elastic anisotropy. All these observations seem to indicate that non-180 deg. ferroelectric domain wall movements occur under indentation stresses and cause anelasticity. Stresses for maximum anelastic deformation are compared with those for recently reported stress-induced depolarization

  12. Effect of La and W dopants on dielectric and ferroelectric properties of PZT thin films prepared by sol-gel process

    International Nuclear Information System (INIS)

    Xiao, Mi; Zhang, Zebin; Zhang, Weikang; Zhang, Ping

    2018-01-01

    La or W-doped lead zirconate titanate thin films (PLZT or PZTW) were prepared on platinized silicon substrates by sol-gel process. The effects of La or W dopant on the phase development, microstructure, dielectric and ferroelectric characteristics of films were studied. For PLZT films, the optimum doping concentration was found to be 2 mol%. While for PZTW films, the dielectric and ferroelectric properties were found to be improved as the doping concentration increased. The fatigue properties of PLZT and PZTW thin films were also investigated, the results showed that A- or B-site donor doping could improve the fatigue properties of PZT thin films. The theory of oxygen vacancy was used to explain the performance improvement caused by donor doping. (orig.)

  13. Effect of La and W dopants on dielectric and ferroelectric properties of PZT thin films prepared by sol-gel process

    Science.gov (United States)

    Xiao, Mi; Zhang, Zebin; Zhang, Weikang; Zhang, Ping

    2018-01-01

    La or W-doped lead zirconate titanate thin films (PLZT or PZTW) were prepared on platinized silicon substrates by sol-gel process. The effects of La or W dopant on the phase development, microstructure, dielectric and ferroelectric characteristics of films were studied. For PLZT films, the optimum doping concentration was found to be 2 mol%. While for PZTW films, the dielectric and ferroelectric properties were found to be improved as the doping concentration increased. The fatigue properties of PLZT and PZTW thin films were also investigated, the results showed that A- or B-site donor doping could improve the fatigue properties of PZT thin films. The theory of oxygen vacancy was used to explain the performance improvement caused by donor doping.

  14. A silicon doped hafnium oxide ferroelectric p–n–p–n SOI tunneling field–effect transistor with steep subthreshold slope and high switching state current ratio

    Directory of Open Access Journals (Sweden)

    Saeid Marjani

    2016-09-01

    Full Text Available In this paper, a silicon–on–insulator (SOI p–n–p–n tunneling field–effect transistor (TFET with a silicon doped hafnium oxide (Si:HfO2 ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band–to–band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3 and strontium bismuth tantalate (SrBi2Ta2O9 provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling barrier width. Compared with the conventional p–n–p–n SOI TFET, the on–state current and switching state current ratio are appreciably increased; and the average subthreshold slope (SS is effectively reduced. The simulation results of Si:HfO2 ferroelectric p–n–p–n SOI TFET show significant improvement in transconductance (∼9.8X enhancement at high overdrive voltage and average subthreshold slope (∼35% enhancement over nine decades of drain current at room temperature, indicating that this device is a promising candidate to strengthen the performance of p–n–p–n and conventional TFET for a switching performance.

  15. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    NARCIS (Netherlands)

    Cai, R.; Kassa, H.G.; Haouari, R.; Marrani, A.; Geerts, Y.H.; Ruzié, C.; Breemen, A.J.J.M. van; Gelinck, G.H.; Nysten, B.; Hu, Z.; Jonas, A.M.

    2016-01-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and

  16. Novel ferroelectric capacitor for non-volatile memory storage and biomedical tactile sensor applications

    International Nuclear Information System (INIS)

    Liu, Shi Yang; Chua, Lynn; Tan, Kian Chuan; Valavan, S.E.

    2010-01-01

    We report on novel ferroelectric thin film compositions for use in non-volatile memory storage and biomedical tactile sensor applications. The lead zirconate titanate (PZT) composition was modified by lanthanum (La 3+ ) (PLZT) and vanadium (V 5+ ) (PZTV, PLZTV) doping. Hybrid films with PZTV and PLZTV as top layers are also made using seed layers of differing compositions using sol-gel and spin coating methods. La 3+ doping decreased the coercive field, polarization and leakage current, while increasing the relative permittivity. V 5+ doping, while having similar effects, results in an enhanced polarization, with comparable dielectric loss characteristics. Complex doping of both La 3+ and V 5+ in PLZTV, while reducing the polarization relative to PZTV, significantly decreases the coercive field. Hybrid films have a greater uniformity of grain formation than non-hybrid films, thus decreasing the coercive field, leakage current and polarization fatigue while increasing the relative permittivity. Analysis using X-ray diffraction (XRD) verified the retention of the PZT perovskite structure in the novel films. PLZT/PZTV has been identified as an optimal ferroelectric film composition due to its desirable ferroelectric, fatigue and dielectric properties, including the highest observed remnant polarization (P r ) of ∼ 25 μC/cm 2 , saturation polarization (P sat ) of ∼ 58 μC/cm 2 and low coercive field (E c ) of ∼ 60 kV/cm at an applied field of ∼ 1000 kV/cm, as well as a low leakage current density of ∼ 10 -5 A/cm 2 at 500 kV/cm and fatigue resistance of up to ∼ 10 10 switching cycles.

  17. Improvement of the fatigue and the ferroelectric properties of PZT films through a LSCO seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Sofia A.S., E-mail: sofiarodrigues@fisica.uminho.pt; Silva, José P.B.; Khodorov, Anatoli; Martín-Sánchez, Javier; Pereira, M.; Gomes, M.J.M.

    2013-11-01

    Highlights: • Pulsed laser deposited PZT thin films. • Seed layer effect on the structural and ferroelectric properties of the PZT films. • The stability of P{sub r} was improved with the introduction of the LSCO layer. -- Abstract: The ability to optimizate the preparation of Lead Zirconate Titanate (PZT) films on platinized Si substrate by pulsed laser deposition was demonstrated. The effect of the modification of the interface film/electrode through the use of a (La,Sr)CoO{sub 3} (LSCO) seed layer on the remnant polarization, fatigue endurance and stress in PZT films was studied. An improvement on the ferroelectric properties was found with the using of the LSCO layer. A remnant polarization (P{sub r}) of 19.8 μC/cm{sup 2} and 4.4 μC/cm{sup 2} for films with and without the LSCO layer were found. In the same way the polarization fatigue decreases significantly after deposition of the LSCO layer between the film and substrate. Atomic force microscopy (AFM) images revealed a different growth process in the films. Current–voltage (I–V) measurements showed that the use of LSCO seed layer improves the leakage current and, on the other hand the conduction mechanisms in the film without LSCO, after the fatigue test, was found to be changed from Schottky to Poole–Frenkel. The trap activation energy (about 0.14 eV) determined from Poole–Frenkel mode agrees well with the energy level of oxygen vacancies. The films stresses were estimated by XRD in order to explain the improvement on the structure and consequentially ferroelectric properties of the films. The model proposed by Dawber and Scott was found to be in agreement with our experimental data, which seems to predict that the oxygen vacancies play an important role on fatigue.

  18. The tide in the seas of Titan

    International Nuclear Information System (INIS)

    Sagan, C.; Dermott, S.F.

    1982-01-01

    It is argued that, if Titan has oceans consisting of liquid methane, then the present high eccentricity of the satellite necessitates that the depth would be greater than 400 m. Such an ocean should be detectable by radar. The effects of tidal dissipation due to the possible existence of an ocean on Titan are considered. (author)

  19. Flexible graphene–PZT ferroelectric nonvolatile memory

    International Nuclear Information System (INIS)

    Lee, Wonho; Ahn, Jong-Hyun; Kahya, Orhan; Toh, Chee Tat; Özyilmaz, Barbaros

    2013-01-01

    We report the fabrication of a flexible graphene-based nonvolatile memory device using Pb(Zr 0.35 ,Ti 0.65 )O 3 (PZT) as the ferroelectric material. The graphene and PZT ferroelectric layers were deposited using chemical vapor deposition and sol–gel methods, respectively. Such PZT films show a high remnant polarization (P r ) of 30 μC cm −2 and a coercive voltage (V c ) of 3.5 V under a voltage loop over ±11 V. The graphene–PZT ferroelectric nonvolatile memory on a plastic substrate displayed an on/off current ratio of 6.7, a memory window of 6 V and reliable operation. In addition, the device showed one order of magnitude lower operation voltage range than organic-based ferroelectric nonvolatile memory after removing the anti-ferroelectric behavior incorporating an electrolyte solution. The devices showed robust operation in bent states of bending radii up to 9 mm and in cycling tests of 200 times. The devices exhibited remarkable mechanical properties and were readily integrated with plastic substrates for the production of flexible circuits. (paper)

  20. Impact induced depolarization of ferroelectric materials

    Science.gov (United States)

    Agrawal, Vinamra; Bhattacharya, Kaushik

    2018-06-01

    We study the large deformation dynamic behavior and the associated nonlinear electro-thermo-mechanical coupling exhibited by ferroelectric materials in adiabatic environments. This is motivated by a ferroelectric generator which involves pulsed power generation by loading the ferroelectric material with a shock, either by impact or a blast. Upon impact, a shock wave travels through the material inducing a ferroelectric to nonpolar phase transition giving rise to a large voltage difference in an open circuit situation or a large current in a closed circuit situation. In the first part of this paper, we provide a general continuum mechanical treatment of the situation assuming a sharp phase boundary that is possibly charged. We derive the governing laws, as well as the driving force acting on the phase boundary. In the second part, we use the derived equations and a particular constitutive relation that describes the ferroelectric to nonpolar phase transition to study a uniaxial plate impact problem. We develop a numerical method where the phase boundary is tracked but other discontinuities are captured using a finite volume method. We compare our results with experimental observations to find good agreement. Specifically, our model reproduces the observed exponential rise of charge as well as the resistance dependent Hugoniot. We conclude with a parameter study that provides detailed insight into various aspects of the problem.