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Sample records for ca sc ti

  1. No-Core Shell Model for 48-Ca, 48-Sc and 48-Ti

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, S; Stoica, S; Vary, J P; Navratil, P

    2004-10-26

    The authors report the first no-core shell model results for {sup 48}Ca, {sup 48}Sc and {sup 48}Ti with derived and modified two-body Hamiltonians. We use an oscillator basis with a limited {bar h}{Omega} range around 40/A{sup 1/3} = 11 MeV and a limited model space up to 1 {bar h}{Omega}. No single-particle energies are used. They find that the charge dependence of the bulk binding energy of eight A = 48 nuclei is reasonably described with an effective Hamiltonian derived from the CD-Bonn interaction while there is an overall underbinding by about 0.4 MeV/nucleon. However, resulting spectra exhibit deficiencies that are anticipated due to: (1) basis space limitations and/or the absence of effective many-body interactions; and, (2) the absence of genuine three-nucleon interactions. They introduce phenomenological modifications to obtain fits to total binding and low-lying spectra. The resulting no-core shell model opens a path for applications to experiments such as the double-beta ({beta}{beta}) decay process.

  2. Enhanced Energy-Storage Density and High Efficiency of Lead-Free CaTiO3-BiScO3 Linear Dielectric Ceramics.

    Science.gov (United States)

    Luo, Bingcheng; Wang, Xiaohui; Tian, Enke; Song, Hongzhou; Wang, Hongxian; Li, Longtu

    2017-06-14

    A novel lead-free (1 - x)CaTiO3-xBiScO3 linear dielectric ceramic with enhanced energy-storage density was fabricated. With the composition of BiScO3 increasing, the dielectric constant of (1 - x)CaTiO3-xBiScO3 ceramics first increased and then decreased after the composition x > 0.1, while the dielectric loss decreased first and increased. For the composition x = 0.1, the polarization was increased into 12.36 μC/cm2, 4.6 times higher than that of the pure CaTiO3. The energy density of 0.9CaTiO3-0.1BiScO3 ceramic was 1.55 J/cm3 with the energy-storage efficiency of 90.4% at the breakdown strength of 270 kV/cm, and the power density was 1.79 MW/cm3. Comparison with other lead-free dielectric ceramics confirmed the superior potential of CaTiO3-BiScO3 ceramics for the design of ceramics capacitors for energy-storage applications. First-principles calculations revealed that Sc subsitution of Ti-site induced the atomic displacement of Ti ions in the whole crystal lattice, and lattice expansion was caused by variation of the bond angles and lenghths. Strong hybridization between O 2p and Ti 3d was observed in both valence band and conduction band; the hybridization between O 2p and Sc 3d at high conduction band was found to enlarge the band gap, and the static dielectric tensors were increased, which was the essential for the enhancement of polarization and dielectric properties.

  3. On 3d bonding in the transition metal trimers - The electronic structure of equilateral triangle Ca3, Sc3, Sc3(+), and Ti3(+)

    Science.gov (United States)

    Walch, S. P.; Bauschlicher, C. W., Jr.

    1985-01-01

    It is pointed out that transition metals and transition metal (TM) compounds are currently of considerable interest because of their relevance to catalysis and to materials science problems such as hydrogen embrittlement and crack propagation in metals. The present paper is concerned with complete active space Self-Consistent Field (SCF) externally contracted configuration interaction (CASSCF/CCI) calculations for the low-lying states of Sc3 and Sc3(+). A comparison is conducted regarding the bonding in the Ca3, Sc3, and Cu3 molecules. This comparison makes it possible to predict general trends for the TM trimers. Attention is given to the qualitative features of the bonding in the TM trimers, the basis sets and other technical details of the calculations, the calculated results for Sc3 and Sc3(+), and conclusions from this work.

  4. High spin structure study of the light Odd-A f{sub 7/2} nuclei: {sup 45}Sc,{sup 45}Ti and {sup 43}Ca

    Energy Technology Data Exchange (ETDEWEB)

    Bednarczyk, P.; Styczen, J.; Broda, R.; Lach, M.; Meczynski, W. [Henryk Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland); Bazzacco, D.; Brandolini, F.; Lunardi, S.; Mueller, L.; Medina, N.H.; Petrache, C.M.; Rossi Alvarez, C.; Scarlassara, F.; Segato, G.F.; Signorini, C. [Dipartimento di Fisica dell`Universita Padova (Italy)]|[INFN Padova (Italy); de Angelis, G.; Napoli, D.R. [INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Soramel, F. [Dipartimento di Fisica dell`Universita Udine (Italy)]|[INFN Udine (Italy)

    1998-06-01

    High-spin states in {sup 45}Sc, {sup 45}Ti and {sup 43}Ca were studied by means of multiple {gamma}- and {gamma}-recoil-coincidences with the use of the GASP array and the recoil mass spectrometer. The nuclei were populated in the 60 MeV {sup 18}O+{sup 30}Si reaction. For the DSAM lifetime measurement the {sup 35}Cl+{sup 12}C reversed kinematics reaction was used. In the article, a complete description of the experimental techniques used in course of the performed experiments is presented. The level schemes and the detailed information on the observed state properties, including B(M1) and B(E2) transition rates are inserted as well as their shell model interpretation. (orig.) With 15 figs., 7 tabs., 31 refs.

  5. Stark broadening parameter tables for Sc X, Sc XI, Ti XI and Ti XII

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.S.

    1998-01-01

    Full Text Available By using the semiclassical-perturbation formalism, we have calculated electron-, proton-, and He III-impact line widths and shifts for 4 Sc X, 10 Sc XI, 4 Ti XI and 27 Ti XII multiplets, significant for investigation and modeling of different plasmas in astrophysics and physics. For Sc X calculations have been performed within the temperature range from 200,000 K to 5,000,000 K, and for perturber densities 1019cm−3 - 1022cm−3. Stark broadening data for Sc XI are tabulated for temperatures from 500,000 K to 5,000,000 K, and perturber densities 1018cm−3 - 1022cm−3. For Ti XI calculations were performed within the temperature range from 500,000 K to 5,000,000 K, and perturber densities 1018cm−3 - 1022cm−3, while for Ti XII results are given for temperatures from 500,000 K to 6,000,000 K, and perturber densities 1018cm−3 - 1023cm−3.

  6. Enrichment of Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residues

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Bona; Li, Guanghui, E-mail: liguangh@csu.edu.cn; Luo, Jun; Ye, Qing; Liu, Mingxia; Peng, Zhiwei; Jiang, Tao

    2017-06-05

    Highlights: • Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residue were successfully enriched. • H{sub 3}PO{sub 4} and NaOH were efficient for enriching Sc{sub 2}O{sub 3} and TiO{sub 2} by removing SiO{sub 2}, Al{sub 2}O{sub 3}, and partial Fe{sub 2}O{sub 3} and CaO. • Enriching mechanism of Sc{sub 2}O{sub 3} and TiO{sub 2} was explicitly explained. - Abstract: As a major byproduct generated in the alumina industry, bauxite ore residue is an important reserve of scandium and titanium. In this study, the feasibility and mechanism of enriching Sc{sub 2}O{sub 3} and TiO{sub 2} from a non-magnetic material, which was obtained from carbothermal reductive roasting and magnetic separation of bauxite ore residue, were investigated based on a two-step (acidic and alkali) leaching process. It was revealed that approximately 78% SiO{sub 2} and 30–40% of CaO, FeO and Al{sub 2}O{sub 3} were removed from a non-magnetic material with 0.0134 wt.% Sc{sub 2}O{sub 3} and 7.64 wt.% TiO{sub 2} by phosphoric acidic leaching, while about 95% Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} were further leached by subsequent sodium hydroxide leaching of the upper-stream leach residue. A Sc{sub 2}O{sub 3}-, TiO{sub 2}- rich material containing 0.044 wt.% Sc{sub 2}O{sub 3} and 25.5 wt.% TiO{sub 2} was obtained, the recovery and the enrichment factor of Sc{sub 2}O{sub 3} and TiO{sub 2} were about 85% and 5, respectively. The enrichment of Sc{sub 2}O{sub 3} was attributed to higher pH (>3.3) of phosphoric acid solution than its dissolution pH{sup 0}, and the enrichment of TiO{sub 2} was mainly associated with the insoluble perovskite (CaTiO{sub 3}) in the acidic solution at ambient temperature. As Sc{sub 2}O{sub 3} and TiO{sub 2} cannot be dissolved in the alkali solution, they were further enriched in the leach residue.

  7. Structural, elastic and thermodynamic properties of Ti2SC

    Indian Academy of Sciences (India)

    Administrator

    Furthermore, at 316 ± 2 GPa, its Young's modulus is the highest one among M2AX .... Young's modulus E (GPa), Poisson's ratio σ, thermal expansion α (10–5 K–1), Grüneisen parameter γ and elastic constants Cij (GPa) of Ti2SC compared with ..... where E(V) is the total energy per unit cell, PV corre- sponds to the constant ...

  8. Cyclotron production of high purity (44m,44)Sc with deuterons from (44)CaCO3 targets.

    Science.gov (United States)

    Alliot, C; Kerdjoudj, R; Michel, N; Haddad, F; Huclier-Markai, S

    2015-06-01

    Due to its longer half-life, (44)Sc (T1/2 = 3.97 h) as a positron emitter can be an interesting alternative to (68)Ga (T1/2 = 67.71 min). It has been already proposed as a PET radionuclide for scouting bone disease and is already available as a (44)Ti/(44)Sc generator. (44)Sc has an isomeric state, (44 m)Sc (T1/2 = 58.6 h), which can be co-produced with (44)Sc and that has been proved to be considered as an in-vivo PET generator (44 m)Sc/(44)Sc. This work presents the production route of (44 m)Sc/(44)Sc generator from (44)Ca(d,2n), its extraction/purification process and the evaluation of its performances. Irradiation was performed in a low activity target station using a deuteron beam of 16 MeV, which favors the number of (44 m)Sc atoms produced simultaneously to (44)Sc. Typical irradiation conditions were 60 min at 0.2 μA producing 44 MBq of (44)Sc with a (44)Sc/(44 m)Sc activity ratio of 50 at end of irradiation. Separations of the radionuclides were performed by means of cation exchange chromatography using a DGA® resin (Triskem). Then, the developed process was applied with bigger targets, and could be used for preclinical studies. The extraction/purification process leads to a radionucleidic purity higher than 99.99% ((43)Sc, (46)Sc, (48)Sc < DL). (44 m)Sc/(44)Sc labeling towards DOTA moiety was performed in order to get an evaluation of the specific activities that could be reached with regard to all metallic impurities from the resulting source. Reaction parameters of radiolabeling were optimized, reaching yields over 95%, and leading to a specific activity of about 10-20 MBq/nmol for DOTA. A recycling process for the enriched (44)Ca target was developed and optimized. The quality of the final batch with regard to radionucleidic purity, specific activity and metal impurities allowed a right away use for further radiopharmaceutical evaluation. This radionucleidic pair of (44 m)Sc/(44)Sc offers a quite interesting PET radionuclide for being further

  9. Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.

    Science.gov (United States)

    Junghans, Katrin; Ghiassi, Kamran B; Samoylova, Nataliya A; Deng, Qingming; Rosenkranz, Marco; Olmstead, Marilyn M; Balch, Alan L; Popov, Alexey A

    2016-09-05

    The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  10. Kinetics and microstructure evolution of Ti{sub 2}SC during in situ synthesis process

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wen Bin, E-mail: siwuya1984@hotmail.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Song, Jing Hong [Center for Materials Research and Analysis, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Mei, Bing Chu [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2013-07-25

    Highlights: •We first fabricate bulk Ti{sub 2}SC by using in situ/hot press method. •The reaction path of Ti{sub 2}SC formation is investigated. •The densification process of bulk sample is observed. -- Abstract: Using in situ reaction method, we have studied the sinter process of the layered ternary Ti{sub 2}SC with Ti, TiS{sub 2} and C powders as initial materials. By XRD and thermodynamic calculations we know that Ti{sub 2}SC is the final result of the reaction between TiS and TiC. TiS is an important intermediate which is more possible the result of TiS{sub 2} and Ti rather than the decomposition of TiS{sub 2}. DSC curves are used to investigate the reaction kinetics of the whole sintering process. By Kissinger and Ozawa method the activation energy are separately calculated to be 125.4 kJ/mol and 134.9 kJ/mol. We also have observed the grain growth and densification process of bulk sample by SEM.

  11. Enhanced hardness in epitaxial TiAlScN alloy thin films and rocksalt TiN/(Al,Sc)N superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Bivas [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Lawrence, Samantha K.; Bahr, David F. [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Schroeder, Jeremy L.; Birch, Jens [Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Sands, Timothy D. [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-10-13

    High hardness TiAlN alloys for wear-resistant coatings exhibit limited lifetimes at elevated temperatures due to a cubic-AlN to hexagonal-AlN phase transformation that leads to decreasing hardness. We enhance the hardness (up to 46 GPa) and maximum operating temperature (up to 1050 °C) of TiAlN-based coatings by alloying with scandium nitride to form both an epitaxial TiAlScN alloy film and epitaxial rocksalt TiN/(Al,Sc)N superlattices on MgO substrates. The superlattice hardness increases with decreasing period thickness, which is understood by the Orowan bowing mechanism of the confined layer slip model. These results make them worthy of additional research for industrial coating applications.

  12. Naked (C5Me5)(2)M cations (M = Sc, Ti, and V) and their fluoroarene complexes

    NARCIS (Netherlands)

    Bouwkamp, MW; Budzelaar, PHM; Gercama, J; Morales, ID; de Wolf, J; Meetsma, A; Troyanov, SI; Teuben, JH; Hessen, B; Budzelaar, Peter H.M.; Hierro Morales, Isabel Del; Troyanov, Sergei I.

    2005-01-01

    The ionic metallocene complexes [Cp*M-2][BPh4] (CP* = C5Me5) of the trivalent 3d metals Sc, Ti, and V were synthesized and structurally characterized. For M Sc, the anion interacts weakly with the metal center through one of the phenyl groups, but for M = Ti and V, the cations are naked. They each

  13. Quantum critical point in the Sc-doped itinerant antiferromagnet TiAu

    Science.gov (United States)

    Svanidze, E.; Besara, T.; Wang, J. K.; Geiger, D.; Prochaska, L.; Santiago, J. M.; Lynn, J. W.; Paschen, S.; Siegrist, T.; Morosan, E.

    2017-06-01

    We present an experimental realization of a quantum critical point in an itinerant antiferromagnet composed of nonmagnetic constituents, TiAu. By partially substituting Ti with Sc in Ti1 -xScxAu , a doping amount of xc=0.13 ±0.01 induces a quantum critical point with minimal disorder effects. The accompanying non-Fermi liquid behavior is observed in both the resistivity ρ ∝T and specific heat Cp/T ∝-ln T , characteristic of a two-dimensional antiferromagnet. The quantum critical point is accompanied by an enhancement of the spin fluctuations, as indicated by the diverging Sommerfeld coefficient γ at x =xc .

  14. Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys.

    Science.gov (United States)

    Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey

    2017-12-01

    The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

  15. Apparent vanishing of ferroelectricity in nanostructured BiScO3PbTiO3

    OpenAIRE

    2010-01-01

    Abstract Nanostructured ceramics of high-temperature piezoelectric 0.375BiScO 3 -0.625PbTiO 3 were prepared by spark plasma sintering of nanocrystalline powders obtained by mechanosynthesis. The macroscopic electrical properties were characterized on dense ceramics with decreasing average grain size down to 28 nm. Results indicate that the electric field is screened by the electrically insulating grain boundaries at the nanoscale, which needs to be considered when discussing size effects i...

  16. Phase transformations of (Ca, Ti)-partially stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Hon Yungshon; Shen Pouyan (Inst. of Materials Science and Engineering, Nation Sun Yat-Sen Univ., Kaohsiung (Taiwan))

    1991-01-20

    The results of phase transformation and microstructural investigation of the ZrO{sub 2}-rich corner of the CaO-TiO{sub 2}-ZrO{sub 2} system are reported. Samples of Ca-PSZ powder (where PSZ is partially stabilized zirconia) containing 10.8 mol.% CaO, had added to them 0-14 mol.% TiO{sub 2} (designated specimens 0T to 14T). The samples were sintered at 1600deg C for 6 h and studied by X-ray diffraction and electron microscopy. Saturation of TiO{sub 2} in the cubic (c) zirconia was reached at a total TiO{sub 2} addition of about 4 mol.% at 1600deg C, whereas the solubility limit in tetragonal (t) zirconia was not reached in the composition range studied. The t-zirconia precipitates remained tweed in the cubic matrix for specimens 2T and 4T, but became lenticular with the (101) habit plane for specimens having a larger TiO{sub 2} content (e.g. 8T). The amount of t-zirconia increased with increasing TiO{sub 2} content at 1600deg C. The addition of TiO{sub 2} also enhanced the eutectoid decomposition of Ca-PSZ to form the PHI{sub 1}-phase (CaZr{sub 4}O{sub 9}). Calzirtite (Ca{sub 2}Zr{sub 5}Ti{sub 2}O{sub 16}) was precipitated from the shell of the zirconia grains in specimen 8T. (orig.).

  17. Separation of (44)Ti from proton irradiated scandium by using solid-phase extraction chromatography and design of (44)Ti/(44)Sc generator system.

    Science.gov (United States)

    Radchenko, V; Meyer, C A L; Engle, J W; Naranjo, C M; Unc, G A; Mastren, T; Brugh, M; Birnbaum, E R; John, K D; Nortier, F M; Fassbender, M E

    2016-12-16

    Scandium-44g (half-life 3.97h [1]) shows promise for positron emission tomography (PET) imaging of longer biological processes than that of the current gold standard, (18)F, due to its favorable decay parameters. One source of (44g)Sc is the long-lived parent nuclide (44)Ti (half-life 60.0 a). A (44)Ti/(44g)Sc generator would have the ability to provide radionuclidically pure (44g)Sc on a daily basis. The production of (44)Ti via the (45)Sc(p,2n) reaction requires high proton beam currents and long irradiation times. Recovery and purification of no-carrier added (nca) (44)Ti from scandium metal targets involves complex separation chemistry. In this study, separation systems based on solid phase extraction chromatography were investigated, including branched diglycolamide (BDGA) resin and hydroxamate based ZR resin. Results indicate that ZR resin in HCl media represents an effective (44)Ti/(44g)Sc separation system. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Intermixing and charge neutrality at DyScO{sub 3}/SrTiO{sub 3} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Luysberg, Martina, E-mail: M.Luysberg@fz-juelich.de [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich, D-52425 Juelich (Germany); Heidelmann, Markus; Houben, Lothar; Boese, Markus [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich, D-52425 Juelich (Germany); Heeg, Tassilo [Institute of Bio and Nanosystems, Research Centre Juelich, D-52425 Juelich (Germany); Schubert, Juergen; Roeckerath, Martin [Institute of Bio and Nanosystems, Research Centre Juelich, D-52425 Juelich (Germany)] [JARA, Fundamentals of Future Information Technology (Germany)

    2009-06-15

    Recently, interfaces between complex insulating oxides have attracted much attention due to their broad spectrum of electronic properties. Joining two materials of different polarity can provide highly conducting layers. The polar discontinuity delivers the driving force for a charge accumulation in the interfacial region which has been demonstrated for lanthanum-based perovskite interfaces with SrTiO{sub 3}. Here it is shown that the polar discontinuity can be accommodated by variations in composition of cation lattice planes at the polar oxide interface between DyScO{sub 3} and SrTiO{sub 3}, where DyScO{sub 3} holds the same polarity as the lanthanum-based perovskites. An intermixing extending over two monolayers at the interfaces for both the Dy-Sr sublattice and the Sc-Ti sublattice is quantified. As a result, charge neutrality is established by electrical compensation between neighbouring atomic planes.

  19. Thermoelastic properties of ScB2, TiB2, YB4 and HoB4

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, L.; Staun Olsen, J.

    2011-01-01

    High-pressure X-ray diffraction in ScB2, TiB2, YB4 and HoB4 powders and single crystals has been studied using synchrotron radiation as well as conventional X-rays. The experimental results are supported by calculations using density functional theory. ScB2, YB4 and HoB4 are hard materials (bulk...

  20. Theoretical study of isoelectronic SinM clusters (M=Sc-,Ti,V+; n=14-18)

    DEFF Research Database (Denmark)

    Torres, M. B.; Fernandez Sanchez, Eva; Balbás, L. C.

    2007-01-01

    We study, from first-principles quantum mechanical calculations, the structural and electronic properties of several low-lying energy equilibrium structures of isoelectronic SinM clusters (M=Sc-,Ti,V+) for n=14-18. The main result is that those clusters with n=16 are more stable than its neighbor...

  1. Optical spectroscopy of Ca3Sc2Si3O12, Ca3Y2Si3O12 and Ca3Lu2Si3O12 doped with Pr3+

    NARCIS (Netherlands)

    Ivanovskikh, K.|info:eu-repo/dai/nl/311489605; Meijerink, A.|info:eu-repo/dai/nl/075044986; Piccinelli, F.; Speghini, A.; Zenin, E.I.; Ronda, R.C.; Bettinelli, M.

    2010-01-01

    The silicates Ca3Sc2Si3O12, Ca3Y2Si3O12 and Ca3Lu2Si3O12, both undoped and doped with Pr3+ ions, have been synthesized by solid-state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using

  2. Synthesis of CaTiO3 from calcium titanyl oxalate hexahydrate (CTO ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Calcium titanate, CaTiO3, an importantmicrowave dielectric material and one of major phases in syn- roc (synthetic rock), a titanate ceramic with potential application for fixation of high level nuclear waste was synthesized from calcium titanyl oxalate [CaTiO (C2O4)2⋅6H2O] (CTO) by employing microwave heating ...

  3. Effect of Microstructure on Reliability of Ca(TiZr)O3-Based Multilayer Ceramic Capacitors

    Science.gov (United States)

    Motoki, Tomoo; Naito, Masahiro; Sano, Harunobu; Konoike, Takehiro; Tomono, Kunisaburo

    2000-09-01

    We examined the reliability of Ca(TiZr)O3 (CTZ)-based Ni-electrode multilayer ceramic capacitors (MLCs) prepared by two different processes with particular interest in the microstructure. One process was to calcine the mixture of CaCO3 and TiO2 to prepare CaTiO3 (CT) powder and the mixture of CaCO3 and ZrO2 to prepare CaZrO3 (CZ) powder, and then mix these calcined powders and sinter them to synthesize the CTZ-based ceramics. The other was to calcine the mixture of CaCO3, TiO2 and ZrO2 powders together to prepare CTZ powder and then sinter them. These two processes of CTZ ceramic preparation resulted in a different crystallinity and distribution of the elements. We found that these factors influenced the reliability of CTZ-based MLCs.

  4. Spectroscopy of 54Ti and the systematic behavior of low-energy octupole states in Ca and Ti isotopes

    Science.gov (United States)

    Riley, L. A.; Agiorgousis, M. L.; Baugher, T. R.; Bazin, D.; Blanchard, R. L.; Bowry, M.; Cottle, P. D.; DeVone, F. G.; Gade, A.; Glowacki, M. T.; Kemper, K. W.; Kustina, J. S.; Lunderberg, E.; McPherson, D. M.; Noji, S.; Piekarewicz, J.; Recchia, F.; Sadler, B. V.; Scott, M.; Weisshaar, D.; Zegers, R. G. T.

    2017-12-01

    Excited states of the N =32 nucleus 54Ti have been studied, via both inverse-kinematics proton scattering and one-neutron knockout from 55Ti by a liquid hydrogen target, using the GRETINA γ -ray tracking array. Inelastic proton-scattering cross sections and deformation lengths have been determined. A low-lying octupole state has been tentatively identified in 54Ti for the first time. A comparison of (p ,p') results on low-energy octupole states in the neutron-rich Ca and Ti isotopes with the results of random phase approximation calculations demonstrates that the observed systematic behavior of these states is unexpected.

  5. Structures and Mechanical and Electronic Properties of the Ti2CO2 MXene Incorporated with Neighboring Elements (Sc, V, B and N)

    Science.gov (United States)

    Feng, Li; Zha, Xian-Hu; Luo, Kan; Huang, Qing; He, Jian; Liu, Yijun; Deng, Wei; Du, Shiyu

    2017-04-01

    Ti2CO2, as the representative MXene with semiconducting characteristics and ultrahigh carrier mobility, has attracted increasing attention in material science. Herein, various Ti2CO2 alloys with Ti displaced by neighboring elements Sc and V, or C by B and N are investigated in this paper based on the first-principles density functional calculations. The structures and mechanical and electronic properties are thoroughly studied for the configurations with varying alloying atom concentrations. The choices of alloying elements play a critical role in determining the lattice parameters and layer thickness. The Sc substitutions generally increase the lattice parameter but decrease the layer thickness. In contrast, the introduction of N presents slight influence on the structural parameters. The mechanical strength shows remarkable variations by introducing the alloying elements. The maximum elastic constant c 11 is determined to be 425 GPa in (Ti0.25V0.75)2CO2, and the corresponding minimum value is only 104 GPa found in (Ti0.125Sc0.875)2CO2. With respect to the electronic properties, although B and Sc both present one less valance electron compared to their replaced elements C and Ti, it is easier to realize the p-type semiconductor in the configurations containing Sc. Both the V and N substitutions are capable of generating n-type semiconductors, but their optimal stoichiometric compositions are quite different. Among all the configurations investigated, only (Ti0.5V0.5)2CO2 and (Ti0.375V0.625)2CO2 are magnetic, with their magnetism determined to be 2.61 uB/cell and 1.52 uB/cell, respectively. Thus, the method of alloying neighboring elements provides an effective approach in manipulating the physical properties of the Ti2CO2, which might widen the possible applications of MXene materials.

  6. Effect of Ti/Sc atom ratio on heterogeneous nuclei, microstructure and mechanical properties of A357-0.033Sr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xiaocen [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); Zhao, Naiqin, E-mail: nqzhao@tju.edu.cn [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin, 300072 (China); Li, Jiajun [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); He, Chunnian, E-mail: cnhe08@tju.edu.cn [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin, 300072 (China); Shi, Chunsheng [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); Liu, Enzuo [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); He, Fang; Ma, Liying; Li, Qunying [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2016-08-01

    A systematic study on heterogeneous nucleation, microstructure and mechanical properties of A357-0.033Sr alloys with different Ti/Sc atom ratio was carried out. According to the obtained results, a Ti/Sc atom ratio up to 1:1 did not show much change in the heterogeneous nuclei but at a higher atom ratio level, heterogeneous nuclei have a great change in chemical composition and morphology (from strip Ti-rich phase to the particle-like Ti-rich phase). In addition, compared to the other four alloys studied, the A357-0.033Sr-0.30Sc-0.35Ti alloy with 1:1 atom ratio has the smallest grain size (88 µm), optimum microstructure (morphology, size and distribution of eutectic Si), densest core-shell Al{sub 3}(Sc, Ti), all of which result in the best mechanical properties. Its tensile strength and elongation reach 287 MPa and 3.62% respectively, showing about 11% and 84% increases compared with A357-0.033Sr alloy.

  7. Processing and characterization of CaTiO3 perovskite ceramics

    Directory of Open Access Journals (Sweden)

    Guilherme Gralik

    2014-06-01

    Full Text Available Calcium titanate (CaTiO3 ceramics with perovskite structure were produced by solid state reaction. Calcium carbonate (CaCO3 and titanium dioxide (TiO2 were mixed (in molar ratios 1/1 and 3/2, and the obtained mixtures were calcined at 1150 °C in successive thermal cycles. The obtained samples were characterized by differential thermal analysis, thermogravimetry, X-ray diffraction, measurement of particle size distribution and linear thermal shrinkage. XRD results indicated that the samples have perovskite CaTiO3 structure with small amount of secondary CaO and TiO2 phases, and their phase composition depends on the heat treatment conditions. The measured values of electrical resistivity were within the characteristic range of insulating materials and approach values corresponding to semiconducting ceramics.

  8. New Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} garnet ceramic phosphor for white LED converters

    Energy Technology Data Exchange (ETDEWEB)

    Khaidukov, N. [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Zorenko, Yu.; Zorenko, T.; Iskaliyeva, A.; Paprocki, K. [Institute of Physics, Kazimierz Wielki University Bydgoszcz (Poland); Zhydachevskii, Y.; Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Deun, R. van [L3 - Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry, Ghent University (Belgium); Batentschuk, M. [Department of Materials Science and Engineering VI, Institute of Materials for Energy and Electronic Technology (i-IMEET), University of Erlangen-Nuremberg, Erlangen (Germany)

    2017-05-15

    The results on crystallization and investigation of the luminescent properties of a new prospective ceramic phosphor based on the Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} silicate garnet are presented for the first time in this work. The luminescent properties of Ca{sub 2}YMgScSi{sub 3}O{sub 12}:Ce were compared with the properties of the reference Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Ce ceramic sample. Without any doubt, the results of this research can be suitable for the development of a new generation of white converters based on the Ca{sup 2+}-Si{sup 4+} garnet compounds. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Multifunctional Ti-(Ca,Zr)-(C,N,O,P) films for load-bearing implants.

    Science.gov (United States)

    Shtansky, D V; Gloushankova, N A; Bashkova, I A; Kharitonova, M A; Moizhess, T G; Sheveiko, A N; Kiryukhantsev-Korneev, F V; Petrzhik, M I; Levashov, E A

    2006-07-01

    Films of Ti-Ca-P-C-O-(N), Ti-Ca-C-O-(N) and Ti-Zr-C-O-(N) were deposited by DC magnetron sputtering or ion implantation-assisted magnetron sputtering of composite targets TiC0.5 + 10%Ca10(PO4)6(OH)2, TiC0.5 + 20%(CaO + TiO2) and TiC0.5 + 10%ZrO2 in an Ar atmosphere or reactively in a gaseous mixture of Ar + 14%N2. The microstructure, elemental and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, scanning force microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The films were characterized in terms of their hardness, Young's modulus, elastic recovery, adhesion strength, and friction and wear both in air and under physiological solution. Particular attention was paid to the analysis of deformation and fracture for various film/substrate systems during scratch testing. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments. In vitro studies involved the investigation of adhesion, spreading, and proliferation of MC3T3-E1 osteoblasts and IAR-2 epithelial cells, morphometric analysis, actin cytoskeleton, focal contacts staining, alkaline phosphatase activity and von Kossa staining of osteoblastic culture. Cell culture experiments demonstrated an increase of osteoblastic proliferation on Ca- and P-incorporated films. In vivo studies were fulfilled by subcutaneous implantation of Teflon plates coated with the tested films in mice and analysis of the population of adherent cells on their surfaces. The results obtained show that multicomponent nanostructured Ti-(Ca, Zr)-(C, N, O, P) films possess a combination of high hardness, wear resistance and adhesion strength, reduced Young's modulus, low friction coefficient and high biocompatibility.

  10. Study on the isospin equilibration phenomenon in nuclear reactions 40Ca + 40Ca , 40Ca + 46Ti , 40Ca + 48Ca , 48Ca + 48Ca at 25 MeV/nucleon by using the CHIMERA multidetector

    Science.gov (United States)

    Martorana, N. S.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjee, M. B.; De Luca, S.; De Filippo, E.; Dell'Aquila, D.; Gnoffo, B.; Lanzalone, G.; Lombardo, I.; Maiolino, C.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2017-11-01

    We report on the results obtained by studying nuclear reactions between isotopes of Ca and Ti at 25 MeV/nucleon. We used the multidetector CHIMERA to detect charged reaction products. In particular, we studied two main effects: the isospin diffusion and the isospin drift. In order to study these processes we performed a moving-source analysis on kinetic energy spectra of the isobar nuclei ^{3H} and ^{3He} . This method allows to isolate the emission from the typical sources produced in reactions at Fermi energy: projectile like fragment (PLF), target like fragment (TLF), and mid-velocity (MV) emission. The obtained results are compared to previous experimental investigations and to simulations obtained with CoMD-II model.

  11. Electrical properties of neodymium doped CaBi 4Ti 4O 15 ceramics

    Science.gov (United States)

    Zeng, Jiangtao; Li, Yongxiang; Wang, Dong; Yin, Qingrui

    2005-03-01

    Neodymium doped bismuth layer structure ferroelectrics (BLSFs) ceramics CaBi 4- xNd xTi 4O 15 ( x=0, 0.25, 0.50, 0.75) were prepared by solid-state reaction method. X-ray diffraction pattern showed that single phase was formed when x=0-0.75. The refined lattice parameters showed that a ( b) axes decrease at x=0.25 and increase with more Nd 3+ dopant. The effects of Nd 3+ doping on the dielectric and ferroelectric properties of CaBi 4Ti 4O 15 ceramics are studied. Nd 3+ dopant decreased the Curie temperature linearly, and the dielectric loss, tan δ, as well. The remnant polarization of Nd 3+ doped CaBi 4Ti 4O 15 ceramics was increased by 80% at x=0.25, while more Nd 3+ dopant decreased the remnant polarization. CaBi 3.75Nd 0.25Ti 4O 15 ceramics had the largest piezoelectric constant d33. The structure and properties of CaBi 4- xNd xTi 4O 15 ceramics showed that Nd 3+ may occupy different crystal locations when Nd 3+ content x is less than 0.25 and more than 0.50.

  12. Consequences of Ca multisite occupation for the conducting properties of BaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zulueta, Y.A., E-mail: yohandysalexis.zuluetaleyva@student.kuleuven.be [Departamento de Física, Facultad de Ciencias Naturales, Universidad de Oriente, CP-90500 Santiago de Cuba (Cuba); Department of Chemistry, KU Leuven, B-3001 Leuven (Belgium); Dawson, J.A. [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Leyet, Y. [Departamento de Engenharia de Materiais, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus (Brazil); Departamento de Física, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus, Amazonas (Brazil); Anglada-Rivera, J. [Instituto Federal de Educação Ciência e Tecnologia do Amazonas, Av. 7de Setembro, 1975, 69020-120 Manaus (Brazil); Guerrero, F. [Departamento de Física, Universidade Federal do Amazonas, Av. General Rodrigo Otávio, 6200 – Coroado I, 69077-000 Manaus, Amazonas (Brazil); Silva, R.S. [Departamento de Física, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE (Brazil); Nguyen, Minh Tho [Department of Chemistry, KU Leuven, B-3001 Leuven (Belgium)

    2016-11-15

    In combination with the dielectric modulus formalism and theoretical calculations, a newly developed defect incorporation mode, which is a combination of the standard A- and B-site doping mechanisms, is used to explain the conducting properties in 5 mol% Ca-doped BaTiO{sub 3}. Simulation results for Ca solution energies in the BaTiO{sub 3} lattice show that the new oxygen vacancy inducing mixed mode exhibits low defect energies. A reduction in dc conductivity compared with undoped BaTiO{sub 3} is witnessed for the incorporation of Ca. The conducting properties of 5 mol% Ca-doped BaTiO{sub 3} are analyzed using molecular dynamics and impedance spectroscopy. The ionic conductivity activation energies for each incorporation mode are calculated and good agreement with experimental data for oxygen migration is observed. The likely existence of the proposed defect configuration is also analyzed on the basis of these methods. - Graphical abstract: Oxygen vacancy formation as a result of self-compensation in Ca-doped BaTiO{sub 3}.

  13. Preparation of CaTiO3 Asymmetric Membranes Using Polyetherimide as Binder Polymer

    Directory of Open Access Journals (Sweden)

    Endang Purwanti Setyaningsih

    2016-03-01

    Full Text Available Asymmetric dense and thin membranes have been prepared from powders of perovskite oxide-type CaTiO3 without cracking by phase inversion method. Polyetherimide was used as a polymeric binder in the method. The resulting green membranes, composed of CaTiO3 powder and polyetherimide binder, were sintered at 890, 1100 or 1200 °C. The crystal phase of CaTiO3 was analyzed using X-Ray Diffraction (XRD. The XRD pattern of the synthesized CaTiO3 powder was matched with the reference indicating the formation of CaTiO3 structure. Sintering at 890 °C fails to form a strong membrane. Scanning Electron Microscope (SEM images of the membranes showed that the membrane had the asymmetric structure with dense layer on one side and porous layer on the other side. The pores in the porous layer were both finger-like and sponge-like structure. The mechanical strength of the membranes, which were determined by Vickers micro hardness method, varied from 3.5 to 25.8 Hv. The strongest membrane without any crack was resulted from sintering at 1200°C with hardness values between 19.4 and 25.8 Hv. Thermal expansion coefficients of the asymmetric membranes sintered at 1100 and 1200 °C, measured with Thermomechanical Analyzer (TMA, were 10.82 × 10-6 and 12.78 × 10-6.C-1 respectively.

  14. Electrical and microstructural properties of CaTiO3-doped K1/2Na1 ...

    Indian Academy of Sciences (India)

    KNN) and CaTiO3- modified K1/2Na1/2NbO3 (CTO-KNN) systems, were investigated. Discs doped with 0 to 0.55% mol of CaTiO3 (CTO) were sintered at 1125°C for 2 h. Although minority phases were found in doped samples, CaTiO3 was not ...

  15. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    Science.gov (United States)

    Esteki, S.; Ahmadian, F.

    2017-09-01

    First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot = 22-Ztot and Mtot = 32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

  16. Dielectric Property of Silicate-Doped CaBi4Ti4O15 Thin Films

    Science.gov (United States)

    Ogawa, Shota; Kondoh, Yohta; Kimura, Junichi; Funakubo, Hiroshi; Uchida, Hiroshi

    2012-09-01

    Thin films of silicate-doped CaBi4Ti4O15 were fabricated to enhance the insulating property of one-axis-oriented CaBi4Ti4O15 films under an applied electric field. The crystalline phase of CaBi4Ti4O15, a type of bismuth layer-structured dielectric (BLSD) compound, was successfully grown on (100)LaNiO3/(111)Pt/TiO2/(100)Si with the preferential orientation of the (001) plane by the addition of bismuth silicate with a nominal composition of Bi12SiO20 up to 1.00%. The crystallographic orientation of the (001)BLSD plane normal to the substrate surface was degraded by excessive bismuth silicate addition above 1.50%. The breakdown electric field was increased by bismuth silicate addition up to 2.00% without the degraded relative dielectric permittivity (ɛr) of approximately 230. The bismuth silicate could precipitate between the grain boundaries in the CaBi4Ti4O15 films without an interface reaction or a solid solution that enhances the insulating behavior of the BLSD films.

  17. 40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis.

    Science.gov (United States)

    Nassar, H; Paul, M; Ahmad, I; Ben-Dov, Y; Caggiano, J; Ghelberg, S; Goriely, S; Greene, J P; Hass, M; Heger, A; Heinz, A; Henderson, D J; Janssens, R V F; Jiang, C L; Kashiv, Y; Nara Singh, B S; Ofan, A; Pardo, R C; Pennington, T; Rehm, K E; Savard, G; Scott, R; Vondrasek, R

    2006-02-03

    The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.

  18. Vacancy induced metallicity at the CaHfO3/SrTiO3 interface

    KAUST Repository

    Nazir, Safdar

    2011-03-31

    Density functional theory is used to study the electronic properties of the oxide heterointerfaceCaHfO3/SrTiO3. Structural relaxation is carried out with and without O vacancies. As compared to related interfaces, strongly reduced octahedral distortions are found. Stoichiometric interfaces between the wide band gap insulatorsCaHfO3 and SrTiO3 turn out to exhibit an insulating state. However, interface metallicity is introduced by O vacancies, in agreement with experiment. The reduced octahedral distortions and necessity of O deficiency indicate a less complicated mechanism for the creation of the interfacial electron gas.

  19. Ab initio study of structural and magnetic properties of TM(n)(ferrocene)(n+1) (TM = Sc, Ti, V, Mn) sandwich clusters and nanowires (n = infinity).

    Science.gov (United States)

    Zhang, Xiuyun; Wang, Jinlan; Gao, Yi; Zeng, Xiao Cheng

    2009-03-24

    Structural and magnetic properties of multidecker sandwich clusters TM(n)(ferrocene)(n+1) [TM = V, Ti, Sc, Mn, ferrocene=FeCp(2), n = 1-3] and corresponding one-dimensional sandwich nanowires (n = infinity) are studied by means of gradient-corrected density functional theory. The TM(n)(FeCp(2))(n+1) clusters are highly stable polyferrocene-like sandwich structures due to strong Fe-Cp interaction. The total magnetic moment of TM(n)(FeCp(2))(n+1) (TM = V, Ti, Mn) increases linearly with the size n. More strikingly, Ti(n)(FeCp(2))(n+1) and V(n)(FeCp(2))(n+1) (n = 1-3) exhibit high magnetic moments 4, 8, 12 mu(B) and 1, 6, 11 mu(B), respectively. In contrast, Sc(n)(FeCp(2))(n+1) clusters are paramagnetic. The [TM(FeCp(2))](infinity) sandwich nanowires are ferromagnetic semiconductors whose band gap is 0.361, 0.506, 0.51, and 1.310 eV, respectively, for TM = Ti, Sc, V, and Mn. Among the four sandwich nanowires, [V(FeCp(2))](infinity) nanowire possesses the highest magnetic moment (5 mu(B)) per unit cell.

  20. Subsolidus Phase Relations of the CaO-REOx-CuO Systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) at 900 °C in Air

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2016-01-01

    The subsolidus phase relations of the CaO-REOx-CuO systems (RE = Eu, Tb, Dy, Ho, Er, Lu and Sc) were investigated in air at 900 °C. The pseudo-ternary sections with RE = Tb, Dy, Ho, Er and Lu have a similar structure. They have in common with the RE = Eu system a solid solution of Ca0.833−xRExCuO2......+y composition but the system with RE = Eu differs by the presence of an Eu2CuO4 phase instead of RE2Cu2O5 for RE = Tb, Dy, Ho, Er and Lu. In contrast, the CaO-ScO1.5-CuO section does not contain a Ca0.833−xScxCuO2+y solid solution and is dominated by the CaSc2O4 phase, which has no equivalent...... in the other systems at 900 °C in air....

  1. Green tide deactivation with layered-structure cuboids of Ag/CaTiO3 under UV light.

    Science.gov (United States)

    Lee, Soo-Wohn; Lozano-Sánchez, L M; Rodríguez-González, V

    2013-12-15

    In this work, an alternative to deactivate noxious green tide Tetraselmis suecica in the short-term is proposed by employing Perovskite-like cube-shaped, crystalline CaTiO3 semiconductors functionalized with atomic silver nanoparticles. CaTiO3 was prepared by a microwave-assisted hydrothermal method and then Ag(0)NPs (1 wt% of CaTiO3), were added by the photoreduction method. The XRD results show that crystalline CaTiO3 has an orthorhombic unit cell with a Perovskite-like structure. Images obtained by FESEM and HRTEM microscopies show well-faceted CaTiO3 rectangular prismatic morphology functionalizated with silver nanoparticles ≈ 13.5 nm. XPS and EDS-FESEM has confirmed the composition of CaTiO3 and silver occurring mainly as reduced metal. The UV inactivation of noxious T. suecica with Ag/CaTiO3 nanocomposites formed on bare materials results in complete deactivation of the algae in 12 min. The direct contact between harmful algae and Ag/CaTiO3 nanocomposite is necessary to deactivate the algae and inhibits algae viability. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Fabrication of Ag-Decorated CaTiO₃ Nanoparticles and Their Enhanced Photocatalytic Activity for Dye Degradation.

    Science.gov (United States)

    Xian, T; Yang, H; Huo, Y S; Ma, J Y; Zhang, H M; Su, J Y; Feng, W J

    2016-01-01

    CaTiO₃nanoparticles of 30-40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8-16 nm were deposited onto CaTiO₃particles by a photochemical reduction method to yield CaTiO₃@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO₃ particles exhibit an enhanced photocatalytic activity compared to bare CaTiO₃ particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO₃particles to 72% for CaTiO₃@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH⁻/H₂O to generate hydroxyl (·OH) radicals. ·OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO₃@Ag composites. In addition, it is found that the addition of ethanol, which acts as an ·OH scavenger, leads to a quenching of ·OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that ·OH radicals are the dominant active species responsible for the dye degradation.

  3. Synthesis of CaTiO3 from calcium titanyl oxalate hexahydrate (CTO ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia. Home; Journals; Bulletin of Materials Science; Volume 30; Issue 3. Synthesis of CaTiO3 from calcium titanyl oxalate hexahydrate (CTO) as precursor employing microwave heating technique. B M Patil R S Srinivasa S R Dharwadkar. Ceramics Volume 30 Issue 3 June 2007 pp 225-229 ...

  4. Preparation of high dielectric constant thin films of CaCu3 Ti4 O12 ...

    Indian Academy of Sciences (India)

    Preparation of sol–gel derived CaCu3Ti4O12 (CCTO) thin films using two different sols and their characterization including their dielectric response are reported. The properties of CCTO films depend heavily on solvents used to prepare the sols. Dielectric constant as high as ∼900 at 100 kHz could be obtained when acetic ...

  5. Microwave synthesis and sintering characteristics of CaCu3 Ti4

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. CaCu3Ti4O12 (CCTO) was synthesized and sintered by microwave processing at 2⋅45 GHz, 1⋅1 kW. The optimum calcination temperature using microwave heating was determined to be 950°C for 20 min to obtain cubic CCTO powders. The microwave processed powders were sintered to 94% density at ...

  6. Microwave synthesis and sintering characteristics of CaCu3 Ti4 O12

    Indian Academy of Sciences (India)

    Keywords. Microwave processing; sintering; giant dielectrics; microstructure. Abstract. CaCu3Ti4O12 (CCTO) was synthesized and sintered by microwave processing at 2.45 GHz, 1.1 kW. The optimum calcination temperature using microwave heating was determined to be 950°C for 20 min to obtain cubic CCTO powders.

  7. Growth of Araucaria angustifolia in the Embrapa/Epagri forest reserve, Caçador, SC, Brazil Crescimento de Araucaria angustifolia na Reserva Florestal Embrapa/ Epagri, Caçador, SC

    Directory of Open Access Journals (Sweden)

    Patricia Póvoa de Mattos

    2010-06-01

    Full Text Available Araucaria Forest is one of most threatened phyto-physiognomies in the Atlantic Forest domain,
    presenting great ecological-economical importance. Nevertheless, there are still lacks of knowledge concerning growth and dynamic of important species, as Araucaria angustifolia. The objective of this work was to recover  the past growth of Araucaria angustifolia, native from Caçador, SC, Brazil, by measuring growth rings and to estimate the average periodic diametric increment. The growth rings were counted and measured, using a stereoscope microscope, in increment cores of 0.5 cm collected from 32 adult trees. The measurements were done with LINTAB measuring table, with 0.01 mm of precision. The samples sizes were irregular, varying from 4.2 to 20.2 cm long. The trees presented average diameter breast height (DBH of 76.3 cm, varying from 10.7 to 141.3 cm. The periodic diameter increment from the last 10 years was 0.4 cm, varying from 0.11 to 1.15 cm. It was observed differences among trees, but there was a tendency of reduction of growth rhythm in larger trees, being more
    evident in trees with more than 110 cm of DBH.A Floresta Ombrófila Mista (FOM é uma das fitofisionomias mais ameaçadas da área de domínio da
    Mata Atlântica, apresentando grande importância ecológico-econômica. Apesar disso, ainda existem lacunas de conhecimento sobre a produtividade primária, o crescimento e a dinâmica de espécies importantes, como a Araucaria angustifolia. O presente trabalho tem por objetivo estudar o crescimento anual de Araucaria angustifolia, nativa do Município de Caçador, SC, pela medição dos anéis de crescimento. A contagem e medição dos anéis de crescimento foram feitas com o auxílio de um microscópio estereoscópico, em baguetas de 0,5 cm de diâmetro, coletadas de 32 árvores adultas. As medições foram feitas com o medidor de anéis de crescimento LINTAB, com precisão de 0,01 mm. O comprimento das amostras

  8. Green tide deactivation with layered-structure cuboids of Ag/CaTiO{sub 3} under UV light

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soo-Wohn [Global Research Laboratory, Sun Moon University, Galsan-Ri, Tangjung-Myon, Asan Chungnam 336-708 (Korea, Republic of); Lozano-Sánchez, L.M. [División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055 Col. Lomas 4a sección, C.P. 78216 San Luis Potosí, S.L.P. (Mexico); Rodríguez-González, V., E-mail: vicente.rdz@ipicyt.edu.mx [División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055 Col. Lomas 4a sección, C.P. 78216 San Luis Potosí, S.L.P. (Mexico)

    2013-12-15

    Graphical abstract: Synergic reasons such as mass transfer, morphology, biocide properties, UV-A photoresponse, and electron trapping that reduce recombination on Ag/CaTiO{sub 3} nanocomposites, have the potential for the generation of reactive radicals that promote the fatal irreversible deactivation of Tetraselmis suecica algae in 12 min under UV-A irradiation. -- Highlights: • An alternative to deactivate harmful green tide is proposed by employing Ag/CaTiO{sub 3}. • Particles of perovskite-like have rectangular prisms morphology with AgNPs ∼13 nm. • The cuboids achieve complete inactivation of Tetraselmis suecica algae in 12 min. • AgNPs functionalization induce fatal irreversible damages on the algae surface. -- Abstract: In this work, an alternative to deactivate noxious green tide Tetraselmis suecica in the short-term is proposed by employing Perovskite-like cube-shaped, crystalline CaTiO{sub 3} semiconductors functionalized with atomic silver nanoparticles. CaTiO{sub 3} was prepared by a microwave-assisted hydrothermal method and then Ag{sup 0}NPs (1 wt% of CaTiO{sub 3}), were added by the photoreduction method. The XRD results show that crystalline CaTiO{sub 3} has an orthorhombic unit cell with a Perovskite-like structure. Images obtained by FESEM and HRTEM microscopies show well-faceted CaTiO{sub 3} rectangular prismatic morphology functionalizated with silver nanoparticles ∼13.5 nm. XPS and EDS-FESEM has confirmed the composition of CaTiO{sub 3} and silver occurring mainly as reduced metal. The UV inactivation of noxious T. suecica with Ag/CaTiO{sub 3} nanocomposites formed on bare materials results in complete deactivation of the algae in 12 min. The direct contact between harmful algae and Ag/CaTiO{sub 3} nanocomposite is necessary to deactivate the algae and inhibits algae viability.

  9. Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films

    Energy Technology Data Exchange (ETDEWEB)

    Shtansky, D.V., E-mail: shtansky@shs.misis.ru [National University of Science and Technology “MISIS”, Leninsky prospekt 4, Moscow 119049 (Russian Federation); Batenina, I.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Kuptsov, K.A. [National University of Science and Technology “MISIS”, Leninsky prospekt 4, Moscow 119049 (Russian Federation); Zhitnyak, I.Y.; Anisimova, N.Yu.; Gloushankova, N.A. [N.N. Blokhin Russian Cancer Research Center of RAMS, Kashirskoe shosse 24, Moscow 115478 (Russian Federation)

    2013-11-15

    A key property of multicomponent bioactive nanostructured Ti(C,N)-based films doped with Ca, P, and O (TiCaPCON) that can be improved further is their antibacterial effect that should be achieved without compromising the implant bioactivity and biocompatibility. The present work is focused on the study of structure, chemical, mechanical, tribological, and biological properties of Ag- and Cu-doped TiCaPCON films. The films with Ag (0.4–4 at.%) and Cu (13 at.%) contents were obtained by simultaneous sputtering of a TiC{sub 0.5}–Ca{sub 3}(PO{sub 4}){sub 2} target and either an Ag or a Cu target. The film structure was studied using X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, glow discharge optical emission spectroscopy, and Raman-shift and IR spectroscopy. The films were characterized in terms of their hardness, elastic modulus, dynamic impact resistance, friction coefficient and wear rate (both in air and normal saline), surface wettability, electrochemical behavior and Ag or Cu ion release in normal saline. Particular attention was paid to the influence of inorganic bactericides (Ag and Cu ions) on the bactericidal activity against unicellular yeast fungus Saccharomyces cerevisiae and gram-positive bacteria Lactobacillus acidophilus, as well as on the attachment, spreading, actin cytoskeleton organization, focal adhesions, and early stages of osteoblastic cell differentiation. The obtained results show that the Ag-doped films are more suitable for the protection of metallic surfaces against bacterial infection compared with their Cu-doped counterpart. In particular, an excellent combination of mechanical, tribological, and biological properties makes Ag-doped TiCaPCON film with 1.2 at.% of Ag very attractive material for bioengineering and modification of load-bearing metal implant surfaces.

  10. Surface structures and osteoblast response of hydrothermally produced CaTiO{sub 3} thin film on Ti-13Nb-13Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin-Woo, E-mail: jinwoo@knu.ac.kr [Department of Periodontology, School of Dentistry, Kyungpook National University, 188-1, Samduk 2Ga, Jung-Gu, Daegu 700-412 (Korea, Republic of); Tustusmi, Yusuke [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental Univeristy, Tokyo 101-0062 (Japan); Lee, Chong Soo; Park, Chan Hee [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kim, Youn-Jeong; Jang, Je-Hee [Department of Periodontology, School of Dentistry, Kyungpook National University, 188-1, Samduk 2Ga, Jung-Gu, Daegu 700-412 (Korea, Republic of); Khang, Dongwoo; Im, Yeon-Min [School of Materials Science and Engineering, Gyeongsang National University, Jinju 600-701 (Korea, Republic of); Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental Univeristy, Tokyo 101-0062 (Japan)

    2011-06-15

    This study investigated the surface characteristics and in vitro biocompatibility of a titanium (Ti) oxide layer incorporating calcium ions (Ca) obtained by hydrothermal treatment with or without post heat-treatment in the Ti-13Nb-13Zr alloy. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. In vitro biocompatibility of the Ca-containing surfaces was assessed in comparison with untreated surfaces using a pre-osteoblast cell line. Hydrothermal treatment produced a crystalline CaTiO{sub 3} layer. Post heat-treatment at 400 deg. C for 2 h in air significantly decreased water contact angles in the CaTiO{sub 3} layer (p < 0.001). The Ca-incorporated alloy surfaces displayed markedly increased cell viability and ALP activity compared with untreated surfaces (p < 0.001), and also an upregulated expression of various integrin genes ({alpha}1, {alpha}2, {alpha}5, {alpha}v, {beta}1 and {beta}3) at an early incubation time-point. Post heat-treatment further increased attachment and ALP activity in cells grown on Ca-incorporated Ti-13Nb-13Zr alloy surfaces. The results indicate that the Ca-incorporated oxide layer produced by hydrothermal treatment and a simple post heat-treatment may be effective in improving bone healing in Ti-13Nb-13Zr alloy implants by enhancing the viability and differentiation of osteoblastic cells.

  11. Improved dielectric properties of CaCu3Ti4O12 films with a CaTiO3 interlayer on Pt/TiO2/SiO2/Si substrates prepared by pulsed laser deposition

    Science.gov (United States)

    Lee, Sung-Yun; Kim, Hui Eun; Jo, William; Kim, Young-Hwan; Yoo, Sang-Im

    2015-11-01

    We report the greatly improved dielectric properties of CaCu3Ti4O12 (CCTO) films with a 60 nm-thick CaTiO3 (CTO) interlayer on Pt/TiO2/SiO2/Si substrates. Both CCTO films and CTO interlayers were prepared by pulsed laser deposition (PLD). With increasing the thickness of CCTO from 200 nm to 1.3 μm, the dielectric constants ( ɛ r ) at 10 kHz in both CCTO single-layered and CCTO/CTO double-layered films increased from ˜260 to ˜6000 and from ˜630 to ˜3700, respectively. Compared with CCTO single-layered films, CCTO/CTO double-layered films irrespective of CCTO film thickness exhibited a remarkable decrease in their dielectric losses ( tanδ) (Poole-Frenkel conduction model. [Figure not available: see fulltext.

  12. Tailoring lanthanide doping in perovskite CaTiO3 for luminescence applications.

    Science.gov (United States)

    Yang, Pei; Tai, Bo; Wu, Weikang; Zhang, Jian-Min; Wang, Feng; Guan, Shan; Guo, Wei; Lu, Yunhao; Yang, Shengyuan A

    2017-06-21

    Perovskite oxide materials have been attracting significant attention due to their rich physical and chemical properties. With its proven stability and bio-compatibility, we suggest the lanthanide-doped perovskite to be a promising material for biological luminescence applications. Here, taking CaTiO3 as a concrete example, we systematically investigate its doping properties using first-principles computational methods. We determine the conditions allowing the growth of CaTiO3 against various competing phases. We obtain the formation energies of various intrinsic point defects in the material. The doping configuration and the charge state of the lanthanide dopants are determined. We find that for heavier elements in the lanthanide family, the substitution at the Ca site is favored under p-type growth conditions and tends to be trivalent, whereas the substitution at the Ti site is favored under n-type growth conditions and tends to be divalent. And for lighter elements in the family, the substitution at the Ca site is more favored for most cases and the dopant is more likely to be trivalent. By tuning the growth conditions, one could control the valence state of the lanthanide dopant, which in turn controls the luminescence spectra. We collect and identify the emission peaks in the infrared biological window, based on which possible doping schemes are suggested for bio-labeling and imaging applications.

  13. Improved persistent luminescence of CaTiO{sub 3}:Pr by fluorine substitution and thermochemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Songhak, E-mail: songhak.yoon@empa.ch [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Otal, Eugenio H.; Maegli, Alexandra E.; Karvonen, Lassi; Matam, Santhosh K. [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ebbinghaus, Stefan G. [Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle/Saale (Germany); Walfort, Bernhard [LumiNova AG, Speicherstrasse 60A, CH-9053 Teufen (Switzerland); Hagemann, Hans [Department of Physical Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211 Geneva 4 (Switzerland); Pokrant, Simone [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Weidenkaff, Anke [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Institute for Materials Science, University of Stuttgart, Heisenbergstrasse 3, 70569 Stuttgart (Germany)

    2014-11-15

    Highlights: • Synthesis of fluorine-substituted CaTiO{sub 3}:Pr phosphors. • Rietveld refinement of CaTi(O,F){sub 3}:Pr phosphors. • Afterglow intensity improvement of ca. 450% compared to CaTiO{sub 3}:Pr. - Abstract: Fluorine-substituted CaTiO{sub 3}:Pr phosphors were prepared by a solid-state reaction. Rietveld refinements of powder X-ray diffraction patterns revealed that increasing fluorine-substitution leads to the gradual shrinkage of the unit-cell. Enhanced afterglow intensities were observed with fluorine-substitution. Furthermore, the effect of annealing atmosphere was investigated by thermochemical treatment in different atmospheres (Ar, air and NH{sub 3}). UV–Vis diffuse reflectance spectra and photoluminescence excitation spectra revealed that Pr{sup 4+} in the pristine CaTi(O,F){sub 3}:Pr phosphor was partially reduced to Pr{sup 3+} under NH{sub 3} flow leading to an intensity improvement of ca. 450% compared to CaTiO{sub 3}:Pr. The substantial improvement of afterglow intensity by fluorine substitution and annealing in NH{sub 3} is considered to be connected with the generation of oxygen vacancies and the partial reduction of Pr{sup 4+} to Pr{sup 3+}.

  14. Mechanosynthesis of nanocrystalline CaTi1-xMnxO3-δ

    Directory of Open Access Journals (Sweden)

    Figueiredo, F. M.

    2008-08-01

    Full Text Available The mechanosynthesis of nanocrystalline CaTi1-xMnxO3-δ is reported for the first time. Powdered CaO, TiO2 anatase and Mn2O3 (Aldrich were weighed in the appropriate stoichiometric quantities in order to obtain CaTi1-xMnxO3-δ (x=0.05, 0.10, 0.15, 0.20, 0.30, 0.50 and 0.80 and dry milled in a planetary high-energy ball mill, using zirconia containers and balls, with a 10:1 ball/mass ratio. The planetary rotation was kept constant at 650 rpm and the container at 1300 rpm, in the opposite direction. Powder XRD patterns revealed a perovskite forming from the early milling stages and a completed reaction after 180 min, with no apparent crystalline or amorphous intermediates, indicating significant Mn solubility in CaTiO3. Patterns show a decrease in lattice volume upon Mn substitution, as expected from the lower Mn3+ or Mn4+ ionic radii when compared to Ti4+. The average crystallite size is in the range 5-30 nm, as determined from Williamson-Hall plots and confirmed by high resolution transmission electron microscopy.La mecanosíntesis de CaTi1-xMnxO3-δ nanocristalino es presentada por primera vez. Polvos reactivos de CaO, TiO2 anatasa y Mn2O3 (Aldrich fueron pesados en las cantidades estequiométricas adecuadas para obtener CaTi1-xMnxO3-δ (x=0.05, 0.10, 0.15, 0.20, 0.30, 0.50 y 0.80 por molienda en seco en un molino planetario de alta energía utilizando contenedores y bolas de circona, en una relación masa de bolas : masa de polvo de 10:1. La rotación del planetario se mantuvo constante a 650 revoluciones por minuto (rpm y la del contenedor a 1300 rpm, en el sentido inverso. La formación de una fase con estructura de perovskita fue identificada a través del análisis de los polvos por difracción de rayos X, siendo esta fase claramente mayoritaria en los polvo molidos durante 180 min y sin observarse la formación de compuestos intermediarios. Los patrones de difracción de rayos X también indicaron una disminución de los parámetro de red

  15. Synthesis and characterization of CTO (CaTiO{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.A.S.; Fernandes, T.S. M.; Santiago, A.A.X.; Sombra, A.S.B., E-mail: marceloassilva@yahoo.com.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Sales, J.C. [Universidade Estadual Vale do Acarau (UVA), Sobral, CE (Brazil)

    2011-07-01

    The objective of this work is to study the ceramic material CTO (CaTiO{sub 3}) by X-Ray Diffraction. The composites of CTO are widely used in dielectric resonators in communication systems. The CTO was prepared by solid state method in a planetary high energy ball milling (Fritsch Pulverisette 5). Stoichiometric quantities of CaCO{sub 3} (Aldrich 99%) and TiO{sub 2} (Merck 99%) were dry milled during 4h with a rotational speed of 370 rpm and then calcined at 1000 deg C for 3h. After, the CTO was studied by X-ray diffraction (XRD). The refinement showed that the CTO was formed with 100% mass, the graph of Williamson-Hall showed a homogeneous sample, with a contraction in the crystal lattice and a reasonably small particle size. (author)

  16. Alpha clustering in Ti isotopes: 40,44,48Ca + α resonant scattering

    Directory of Open Access Journals (Sweden)

    Bailey Sam

    2016-01-01

    Full Text Available Measurements were made of the 4He(40,44,48Ca,α resonant scattering reactions at 180° and up to Ec.m. ~ 11.5MeV, using the Thick Target Inverse Kinematics technique. These measurements are discussed, with a focus on assessing their usefulness for investigating α-clustering in medium mass 44,48,52Ti nuclei.

  17. Local character of the highest antiferromagnetic temperature of Ce systems in Sc-rich CeTi1 -xScxGe

    Science.gov (United States)

    Sereni, J. G.; Pedrazzini, P.; Gómez Berisso, M.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C.

    2015-05-01

    The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with TN=47 K , but its local or itinerant nature has not been deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport, and thermal properties of CeTi1 -xScxGe alloys within the range of stability of the CeScSi-type structure: 0.25 ≤x ≤1 . Along this concentration range, this strongly anisotropic system presents a complex magnetic phase diagram with a continuous modification of its magnetic behavior, from ferromagnetism for 0.25 ≤x ≤0.50 (with 7 K≤TC≤16 K ) to AFM for 0.60 ≤x ≤1 (with 19 K≤TN≤47 K ). The onset of the AFM phase is associated to a metamagnetic transition with a critical field increasing from Hcr=0 at x ≈0.55 to ≈6 T at x =1 , coincident with an increasing contribution of the first excited crystal electric field doublet. At a critical point xcr≈0.65 a second transition appears at TL≤TN . In contrast to observations in itinerant systems like CeRh2Si2 or CeRh3B2 , no evidences for significant hybridization of the 4 f electrons at large Sc contents were found. Therefore, the exceptionally large TN of CeScGe can be attributed to an increasing Ruderman-Kittel-Kasuya-Yosida interaction between Ce double layers as Sc content grows.

  18. Enhanced magnetism of perovskite oxides, Sr(Sn,Fe)O3- δ , by substitution of nonmagnetic Ca and Ti ions

    Science.gov (United States)

    Nomura, Kiyoshi; Suzuki, Shigeyo; Mizunuma, Tomoya; Koike, Yuya; Okazawa, Atsushi

    2017-11-01

    Magnetic properties of perovskite oxides, SrSn1- x Fe x O3- δ ( x ≤ 0.15), substituted with nonmagnetic Ca and Ti ions were studied. XRD patterns showed the orthorhombic structure (close to tetragonal) of (Sr1- y Ca y )(Sn1- x Fe x )O3- δ and Sr(Sn1- x- y Fe x Ti y )O3- δ . The cell volumes decreased with the increase of Ca and Ti doping rates. Although Ti-substituted Sr(Sn, Fe)O3- δ showed small saturation magnetizations as compared with non-Ti substituted one, the magnetization increased a little with Ti doping rates up to 15%. On the other hand, all Ca-substituted Sr(Sn, Fe)O3- δ showed larger saturation magnetization than non-Ca substituted one. Two doublets of Fe3+ and a doublet of Fe4+ were observed in Mössbauer spectra of Ca-substituted Sr(Sn, Fe)O3- δ with weak ferromagnetism, and two sextets of high spin Fe3+ were additionally observed in Mössbauer spectra of Ca-doped Sr(Sn, Fe)O3- δ with relatively strong ferromagnetism. When Sr(Sn, Fe)O3- δ were further codoped with Ca and Ti ions, they showed the stable and enhanced ferromagnetic properties. It is considered that magnetic polarons among high spin Fe3+ species are overlapped by shrinking or deforming the crystal structure of perovskite oxides. That is the magnetism induced by a chemical pressure of perovskite oxides.

  19. Study of electro-caloric effect in Ca and Sn co-doped BaTiO3 ceramics

    Science.gov (United States)

    Upadhyay, Sanjay Kumar; Fatima, Iram; Raghavendra Reddy, V.

    2017-04-01

    The present work deals with the study of structural, ferroelectric, dielectric and electro-caloric effects in lead free ferroelectric polycrystalline Ba1-x Ca x Ti0.95Sn0.05O3 (x  =  2, 5 and 10%) i.e. Ca, Sn co-doped BaTiO3 (BTO). Phase purity of the samples is confirmed from x-ray data by using Rietveld refinement. 119Sn Mössbauer reveals homogenous phase as well as iso-valent substitution of Sn at Ti site. Enhancements in ferroelectric and dielectric properties have been observed. Indirect method which is based on Maxwell equation has been used to determine the electro-caloric (EC) effect in the studied ferroelectric ceramics and maximum EC coefficient is observed for Ba0.95Ca0.05Ti0.95Sn0.05O3.

  20. Crystal and magnetic structure of Sr{sub 2}BIrO{sub 6} (B = Sc, Ti, Fe, Co, In) in the framework of multivalent iridium double perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Kayser, Paula; Alonso, Jose A. [School of Chemistry, The University of Sydney, Sydney, NSW (Australia); Mompean, Federico J.; Retuerto, Maria [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco (Spain); Croft, Mark [Niels Bohr Institute, University of Copenhagen (Denmark); Ignatov, Alexander [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 610 Taylor Road, Piscataway, NJ (United States); Fernandez-Diaz, Maria T. [Institut Laue Langevin, Grenoble (France)

    2015-10-15

    The preparation, crystal structure and magnetic properties of Sr{sub 2}BIrO{sub 6} (B = In, Sc, Fe, Co or Ti) oxides are reported. For B = Sc, Fe, Co or In materials, X-ray and neutron powder diffraction (NPD) studies confirm the presence of 1:1 B-ordered perovskite-like structures crystallizing in the monoclinic I2/m and P2{sub 1}/n space groups, with unit-cell parameters a ∼ √2a{sub 0}, b ∼ √2a{sub 0}, c ∼ 2a{sub 0} and β ∼ 90 . Sr{sub 2}TiIrO{sub 6} is described as a disordered perovskite with orthorhombic symmetry in the Pbnm space group. For B = Fe and Co, low-temperature NPD data and magnetic measurements indicate the existence of an antiferromagnetic structure resulting from the Fe{sup 3+}/Co{sup 3+} magnetic moment interaction. X-ray absorption spectroscopy corroborates that the oxidation states of B and Ir are 3+ and 5+, respectively. The bond lengths and other structural features are discussed in the framework of other recently reported iridium double perovskites where iridium adopts tetravalent, pentavalent and hexavalent oxidation states, and in the wider context of Sr double perovskites. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Influence of Cu-doping on the structural and optical properties of CaTiO{sub 3} powders

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, L.H.; Moura, A.P. de [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil); La Porta, F.A., E-mail: felipe_laporta@yahoo.com.br [Department of Chemistry, Federal Technological University of Parana (UTFPR), PO Box 3131, 86036-370, Londrina/PR (Brazil); Nogueira, I.C. [DQ-UFSCar-Universidade Federal de São Carlos, P.O. Box 676, 13565-905, São Carlos, SP (Brazil); Aguiar, E.C.; Sequinel, T. [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil); Rosa, I.L.V. [DQ-UFSCar-Universidade Federal de São Carlos, P.O. Box 676, 13565-905, São Carlos, SP (Brazil); Longo, E.; Varela, J.A. [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil)

    2016-09-15

    Highlights: • Ca{sub 1−x}Cu{sub x}TiO{sub 3} powders were successfully synthesized via a polymeric precursor method. • Effects of Cu incorporated on the Ca-site into the CaTiO{sub 3} lattice as host matrix has been investigated. • The optical behavior reveals that the Ca{sub 1−x}Cu{sub x}TiO{sub 3} powders have potential applications in emerging technologies. - Abstract: Here, we report on the effect of chemical substitution on the structural and optical properties of Cu-doped CaTiO{sub 3} (CTO) polycrystalline powders synthesized by the polymeric precursor method. Our findings are discussed based on the structural order-disorder effects originating from the modification of the Ca{sub 1−x}Cu{sub x}TiO{sub 3} microcrystal matrix. These results may elucidate the compositional modulation and methods of controlling the structural design, as well as reveal the changes in the optical behavior of this system at an atomic level.

  2. Piezoelectric properties of lead-free CaBi4Ti4O15 thin films

    Science.gov (United States)

    Arai, Fumihito; Motoo, Kohei; Fukuda, Toshio; Kato, Kazumi

    2004-11-01

    CaBi4Ti4O15 (CBTi144) thin films are evaluated for use as lead-free thin-film piezoelectrics in microelectromechanical systems. CBTi144 thin films were prepared on Pt substrates by dip coating a precursor solution of metal alkoxides. We fabricated a piezoelectric bimorph actuator using those films and analyzed the displacement induced by the electric field. Young's modulus was measured by the vibrating-reed technique and the piezoelectric constant d31 was derived by analysis of bending displacement and measurement of displacement-voltage curve. The measurements revealed that the CBTi144 films had a large piezoelectric constant d31 of 32pm /V.

  3. Thermoelastic properties of ScB2, TiB2, YB4 and HoB4: Experimental and theoretical studies

    DEFF Research Database (Denmark)

    Waśkowska, A.; Gerward, Leif; Staun Olsen, J.

    2011-01-01

    High-pressure X-ray diffraction in ScB2, TiB2, YB4 and HoB4 powders and single crystals has been studied using synchrotron radiation as well as conventional X-rays. The experimental results are supported by calculations using density functional theory. ScB2, YB4 and HoB4 are hard materials (bulk ...

  4. Investigations of the (nat)Ti(p,x)(43,44m,44g,46,47,48)Sc,(48)V nuclear processes up to 40MeV.

    Science.gov (United States)

    Khandaker, M U; Kim, K; Lee, M W; Kim, K S; Kim, G N; Cho, Y S; Lee, Y O

    2009-01-01

    Independent and cumulative production cross-sections for the (nat)Ti(p,x)(48)V, (43,44m,44g,46,47,48)Sc nuclear processes are reported here, for the energy region of 4-38MeV by using a stacked-foil activation technique. Measured data were critically compared with the earlier reported values, and also with the theoretical data from the TALYS and ALICE-IPPE codes. The measured (nat)Ti(p,x)(48)V reaction is important for charged particle beam monitoring purposes, whereas the (43,44,47)Sc radionuclide have various practical applications in nuclear medicine.

  5. Giant permittivity and Maxwell-Wagner relaxation in Yb : CaTiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Viviani, M; Bassoli, M; Buscaglia, V; Buscaglia, M T [Institute for Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa (Italy); Nanni, P, E-mail: v.buscaglia@ge.ieni.cnr.i [Department of Process and Chemical Engineering, University of Genoa, P.le Kennedy 1, I-16129 Genoa (Italy)

    2009-09-07

    Yb-modified CaTiO{sub 3} ceramics sintered for 24 h at 1450 {sup 0}C exhibit a giant apparent permittivity of about 10{sup 4} with a remarkable temperature (30-300 K) and frequency (10{sup 1}-10{sup 6} Hz) stability (maximum variation: {+-}20%). After a post-annealing treatment of 48 h at 1100 {sup 0}C, the dielectric response is strongly modified, with a high frequency, low temperature permittivity corresponding to the intrinsic dielectric behaviour of CaTiO{sub 3}. A step-like rise in the apparent permittivity and a complex dielectric behaviour is observed with increasing temperature. The overall dielectric response of the ceramics can be interpreted in terms of the Maxwell-Wagner interfacial relaxation and modelled using equivalent circuits. The analysis demonstrates that the as-sintered ceramic consists of semiconducting grains (resistivity <10{sup 4} {Omega} cm at 300 K) and insulating grain boundaries (resistivity {approx}10{sup 7} {Omega} cm at 300 K). Partial reoxidation takes place during post-annealing with the formation of oxygen gradients and increased electrical heterogeneity. In general, the dielectric response will be determined by the extent of the reoxidation reaction during cooling or post-annealing treatment below the sintering temperature.

  6. CaTiO3:Eu3+ red nanophosphor: low temperature synthesis and photoluminescence properties.

    Science.gov (United States)

    Shivram, M; Prashantha, S C; Nagabhushana, H; Sharma, S C; Thyagarajan, K; Harikrishna, R; Nagabhushana, B M

    2014-01-01

    Nanoparticles of Eu3+ doped (1-9 mol%) CaTiO3 were prepared using low temperature (500°C) solution combustion technique using metal nitrates as precursors and urea as fuel. The powder X-ray diffraction patterns of the as-formed products show single orthorhombic phase. The crystallite size was estimated using Scherrer's method and found to be in the range 40-45 nm. The effect of Eu3+ ions on luminescence characteristics of CaTiO3 was studied and the results were discussed in detail. The phosphors exhibit bright red emission upon 398 nm excitation. The characteristic emission peaks recorded at ∼540, 593, 615, 653, 696 and 706 nm (5D0→7Fj=0,1,2,3,4,5) were attributed to Eu3+ ions. The electronic transition corresponding to 5D0→7F2 (615 nm) was stronger than the magnetic dipole transition 5D0→7F1 of Eu3+ ions (596 nm). The CIE chromaticity co-ordinates were calculated from emission spectra, the values (x,y) very close to NTSC standard value of red emission. Therefore, the present phosphors were highly useful for display applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Unique local structures of Ca, Ti, Fe and Zr in natural glasses formed by meteorite impact

    Science.gov (United States)

    Yoshiasa, Akira; Tobase, Tsubasa; Okube, Maki; Wang, Ling; Isobe, Hiroshi; Mashimo, Tsutomu; Graduate School of Science; Technology Collaboration; Materials; Structures Laboratory, Tokyo Institute of Technology Collaboration

    2015-06-01

    The local structures of cation in tektite from six strewn fields, impact-related glass, and non-impact-related glass were studied by Ca, Ti, Fe and Zr K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Shock compression also causes local structural changes of gest and minor elements as well as transition of host structures. How to be left a record is peculiar by each element. The XAFS measurements were performed at the beam lines BL-NW10A and BL-9C, KEK, Japan. The comparison of XANES spectra and bonding distances between crystalline reference minerals and natural glasses was done. Based on the different valence states of iron, the degrees of oxidation states were estimated. The local structures of Ca, Ti and Zr ions are useful probe for physical conditions and formation process of glasses. Tektites experienced high quenching rates and a reduced atmospheric environment when they were ejected into outer space. Other impact-related glass, which was remained close to the crater, experienced a more complicated environment. The local structural changes of cation in the impact-related glass are rich in a variety. Analysis of local structure is help to compare their formation process and distinguish them.

  8. Energy Trapping Characteristics of Bismuth Layer Structured Compound CaBi4Ti4O15

    Science.gov (United States)

    Kimura, Masahiko; Sawada, Takuya; Ando, Akira; Sakabe, Yukio

    1999-09-01

    Piezoelectric characteristics of bismuth layer structured compound CaBi4Ti4O15 ceramics were studied in terms of the energy trapping phenomenon of the second harmonic thickness extensional (TE2) vibration mode. An electrode-buried-type resonator was prepared by the co-firing technique to generate the TE2 mode, and frequency-lowering-type energy trapping was realized. Favorable resonant characteristics were obtained for piezoelectric filter and oscillator applications with narrow frequency tolerances, which require a small electromechanical coupling coefficient and a high mechanical quality factor. The electromechanical coupling coefficient for the TE2 vibration mode of the resonator was 13.9% and the mechanical quality factor Qm was 2560. The temperature coefficient of the resonance frequency was adequate for the applications. The microstructure of CaBi4Ti4O15 ceramic was also investigated. Marked shape anisotropy of the grain was observed; however, preferential grain orientation was not recognized when the ceramic was prepared by the ordinary firing process.

  9. Natural CaO-TiO2-SiO2 based ceramics

    Directory of Open Access Journals (Sweden)

    Jelena Pantić

    2011-06-01

    Full Text Available Lešnica river deposits consist of a large number of minerals of different grain sizes including sphene. Since it is very difficult to obtain pure monophase titanite by different synthetic routes (sol-gel, coprecipitation, combustion, spray pyrolysis and hydrothermal method, the aim of this work was to study the structure of the sphene from the Lešnica river deposits and possibility of using it as a natural precursor for CaO-TiO2-SiO2 based ceramics. The sphene from Lešnica was analyzed by different methods: tristimulus colorimetry, infrared spectroscopy, electron microprobe and X-ray single crystal diffraction. It was confirmed that Al, Fe, Mn and P are present in the sphene structure and proposed that corresponding structural formula could be: (Ca2+1.008 Mn2+0.0021.010(Ti4+0.901 Fe3+0.033 Al3+0.060 P5+0.0010.995 Si4+1.024 O2-5.

  10. Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Santilli do Nascimento Libanori, Gabriela [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Avansi Jr, Waldir [Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Arnold Schimidt, 13566-590 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN/LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, R. Francisco Degni, 55, Bairro Quitandinha, 14801-907 Araraquara, SP (Brazil)

    2015-09-15

    For this research, we studied the influence of titanium tetrachloride (TC) and titanium tetraisopropoxide (TTP) precursors on CaTiO{sub 3} (CTO) synthesis by employing a microwave-assisted hydrothermal (MAH) method regarding their respective short-, medium- and long-range features to determine if the use of different titanium precursors enhances the structural evolution of the material. The growth mechanism for the formation of the micro-cube-shaped CTO is proposed to obtain nanoparticle aggregation of self-assembly nanoplates. The disorder coupled to the oxygen vacancies of [TiO{sub 5}]–[TiO{sub 6}] in complex clusters in the CTO 1 powder and twists in bonding between the [TiO{sub 6}]–[TiO{sub 6}] complex clusters in the CTO 2 powder were mainly responsible for photoluminescent (PL) emission. - Highlights: • Different titanium precursors enhance the structural evolution of the material. • [TiO{sub 5}]–[TiO{sub 6}] and twists in bonding [TiO{sub 6}]–[TiO{sub 6}] were responsible for PL emission. • Micro-cube shaped was formed by nanoparticle aggregation of self-assembly nanoplates.

  11. Fully relativistic analysis of the absorption spectra of Ca{sub 3}Sc{sub 2}Ge{sub 3}O{sub 12}:Ni{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Brik, M.G.; Ogasawara, K. [Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)

    2006-10-15

    Systematic analysis of the energy level schemes, ground state absorption (GSA) and covalency effects for the Ni{sup 2+} ion in Ca{sub 3}Sc{sub 2}Ge{sub 3}O{sub 12} was performed. The recently developed first-principles approach to the analysis of the absorption spectra of impurity ions in crystals based on the discrete variational multi-electron method (DV-ME) [K. Ogasawara et al., Phys. Rev. B 64, 115413 (2001)] was used in the calculations. As a result, complete energy level schemes of Ni{sup 2+} and its absorption spectra at both possible crystallographic positions (distorted octahedral Sc{sup 3+} and tetrahedral Ge{sup 4+} positions) were calculated, assigned and compared with experimental data. Energies of the charge transfer (CT) transitions for both positions are estimated. Numerical contributions of all possible electron configurations into the calculated energy states were determined. By performing analysis of the molecular orbitals (MO) population, it was shown that the covalency of the chemical bonds between the Ni{sup 2+} and O{sup 2-} ions increases in passing from the hexa- to the tetra-coordinated complex. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Judd–Ofelt analysis of Ho{sup 3+} doped in ceramic CaSc{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Georgescu, Şerban [National Institute for Laser, Plasma and Radiation Physics, 409 Atomiştilor Street, 077125 Măgurele-Ilfov (Romania); Ştefan, Angela [National Institute for Laser, Plasma and Radiation Physics, 409 Atomiştilor Street, 077125 Măgurele-Ilfov (Romania); University of Bucharest, Faculty of Physics, 405 Atomistilor Street, 077125 Măgurele-Ilfov (Romania); Toma, Octavian, E-mail: octavian.toma@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 409 Atomiştilor Street, 077125 Măgurele-Ilfov (Romania); Voiculescu, Ana-Maria [National Institute for Laser, Plasma and Radiation Physics, 409 Atomiştilor Street, 077125 Măgurele-Ilfov (Romania)

    2015-06-15

    A Judd–Ofelt analysis was performed on a calcium scandate (CaSc{sub 2}O{sub 4}) ceramic sample doped with 2 at% Ho{sup 3+}. Using the measured lifetime of {sup 5}I{sub 7} level to calibrate the absorption spectrum, the Judd–Ofelt parameters were obtained: Ω{sub 2} = 3.78×10{sup −20} cm{sup 2}, Ω{sub 4} = 5.17×10{sup −20} cm{sup 2}, and Ω{sub 6} = 1.92×10{sup −20} cm{sup 2}. The electric-dipole and magnetic-dipole transition probabilities, radiative lifetimes and luminescence branching ratios were calculated. The quantum efficiency of the green emitting levels ({sup 5}F{sub 4}, {sup 5}S{sub 2}) was found: 54%. The calibration method also allowed the estimation of the ‘effective’ thickness of the ceramic sample: approximately eight times greater than the geometric thickness. - Highlights: • Jud–Ofelt analysis is performed on a Ho(2 at%):CaSc{sub 2}O{sub 4} translucent ceramic sample. • The intensity parameters were calibrated using the lifetime of the {sup 5}I{sub 7} Ho{sup 3+} level. • The luminescence lifetimes of Ho{sup 3+} metastable levels were measured. • Transition rates, radiative lifetimes and quantum efficiencies were calculated. • The quantum efficiency calculated for the green-emitting levels ({sup 5}F{sub 4},{sup 5}S{sub 2}) is 54%.

  13. Investigation of the stability of glass-ceramic composites containing CeTi 2 O 6 and CaZrTi 2 O 7 after ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Paknahad, Elham; Grosvenor, Andrew P.

    2017-12-01

    Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigate the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.

  14. Investigation of the stability of glass-ceramic composites containing CeTi2O6 and CaZrTi2O7 after ion implantation

    Science.gov (United States)

    Paknahad, Elham; Grosvenor, Andrew P.

    2017-12-01

    Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigate the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.

  15. Scanning Probe Microscopy on heterogeneous CaCu3Ti4O12 thin films

    Directory of Open Access Journals (Sweden)

    Fiorenza Patrick

    2011-01-01

    Full Text Available Abstract The conductive atomic force microscopy provided a local characterization of the dielectric heterogeneities in CaCu3Ti4O12 (CCTO thin films deposited by MOCVD on IrO2 bottom electrode. In particular, both techniques have been employed to clarify the role of the inter- and sub-granular features in terms of conductive and insulating regions. The microstructure and the dielectric properties of CCTO thin films have been studied and the evidence of internal barriers in CCTO thin films has been provided. The role of internal barriers and the possible explanation for the extrinsic origin of the giant dielectric response in CCTO has been evaluated.

  16. Bipolar Switching Characteristics of RRAM Cells with CaBi4Ti4O15 Film

    Directory of Open Access Journals (Sweden)

    Jian-Yang Lin

    2014-01-01

    Full Text Available The electrical conduction and bipolar switching properties of resistive random access memory (RRAM cells with transparent calcium bismuth titanate (CaBi4Ti4O15—CBTi144 thin films were investigated. Experimentally, the (119-oriented CBTi144 thin films were deposited onto the ITO/glass substrates by RF magnetron sputtering followed by rapid thermal annealing (RTA at a temperature range of 450–550°C. The surface morphologies and crystal structures of the CBTi144 thin films were examined by using field-emission scanning electron microscopy and X-ray diffraction measurements. The on/off ratio and switching behaviors of the transparent Al/CBTi144/ITO/glass RRAM devices were further discussed in this work.

  17. Microscopic origins of the large piezoelectricity of leadfree (Ba,Ca)(Zr,Ti)O3

    Science.gov (United States)

    Nahas, Yousra; Akbarzadeh, Alireza; Prokhorenko, Sergei; Prosandeev, Sergey; Walter, Raymond; Kornev, Igor; Íñiguez, Jorge; Bellaiche, L.

    2017-06-01

    In light of directives around the world to eliminate toxic materials in various technologies, finding lead-free materials with high piezoelectric responses constitutes an important current scientific goal. As such, the recent discovery of a large electromechanical conversion near room temperature in (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 compounds has directed attention to understanding its origin. Here, we report the development of a large-scale atomistic scheme providing a microscopic insight into this technologically promising material. We find that its high piezoelectricity originates from the existence of large fluctuations of polarization in the orthorhombic state arising from the combination of a flat free-energy landscape, a fragmented local structure, and the narrow temperature window around room temperature at which this orthorhombic phase is the equilibrium state. In addition to deepening the current knowledge on piezoelectricity, these findings have the potential to guide the design of other lead-free materials with large electromechanical responses.

  18. Electrical and microstructural properties of CaTiO3-doped K1/2Na1 ...

    Indian Academy of Sciences (India)

    1213–1217. c Indian Academy of Sciences. Electrical and microstructural properties of CaTiO3-doped. K1/2Na1/2NbO3-lead free ceramics. L RAMAJO. ∗. , R PARRA, M A RAMÍREZ† and M S CASTRO. Institute of Research in Materials Science and Technology (INTEMA), (CONICET – Universidad Nacional de Mar del.

  19. Enhanced Mechanical Properties of MgZnCa Bulk Metallic Glass Composites with Ti-Particle Dispersion

    Directory of Open Access Journals (Sweden)

    Pei Chun Wong

    2016-05-01

    Full Text Available Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf of Ti particles. The results showed that the compressive ductility increased with Vf. The mechanical performance of these BMGCs, with up to 5.4% compressive failure strain and 1187 MPa fracture strength at room temperature, can be obtained for the Mg-based BMGCs with 50 vol % Ti particles, suggesting that these dispersed Ti particles can absorb the energy of the crack propagations and can induce branches of the primary shear band into multiple secondary shear bands. It follows that further propagation of the shear band is blocked, enhancing the overall plasticity.

  20. Investigation of structural, spectral and photometric properties of CaTiO3:Dy3+ nanophosphors for the lighting applications

    Science.gov (United States)

    Singh, Dhananjay Kumar; Manam, Jairam

    2017-07-01

    A series of perovskite CaTiO3:Dy3+ nanophosphors have been prepared via solid state reaction method in order to investigate the structural, spectral and photometric properties. The structural, morphological and spectral properties of prepared nanophosphors were systematically characterized by XRD, FESEM, EDX, Photoluminescence, PL decay time and UV-Visible spectroscopy. The novel CaTiO3:Dy3+ nanophosphors exhibited single phase orthorhombic structure with space group Pbnm. The high magnification FESEM images of prepared sample demonstrated the particle size in the range 220-240 nm. The photoluminescence properties of Dy3+ doped CaTiO3 nanophosphors were investigated through excitation, emission spectra and decay time by varying the concentration of activator (Dy3+). Under the excitation of 386 nm UV light, Dy3+ activated CaTiO3 nanophosphors exhibited its characteristic excellent intense emissions in blue and yellow region around the wavelength 484 and 575 nm due to the transition 4F9/2→6H15/2 and 4F9/2 → 6H13/2 respectively. The photometric parameters such as CIE-coordinate and correlated color temperature (CCT) was also calculated. The CIE- coordinate (0.28, 0.32) was found near white light and CCT value was found to be 9222.31 K for optimum composition Ca0.96TiO3:0.04Dy3+ which was useful for cold light emission. The affirmative experimental results indicated that the prepared nanophosphors could be the favorable candidate for lighting applications.[Figure not available: see fulltext.

  1. A comparative study of the Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15

    Science.gov (United States)

    Tellier, J.; Boullay, Ph.; Manier, M.; Mercurio, D.

    2004-06-01

    The room temperature structures of the four-layer Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15 are determined by means of single crystal X-ray diffraction. Regarding the CaBi 4Ti 4O 15 phase, in agreement with the tolerance factor, a significant deformation of the perovskite blocks is observed. The rotation system of the octahedra is typical from even layer Aurivillius phases and leads to the use of the space group A2 1am. For the BaBi 4Ti 4O 15 phase, only a weak variation with respect to the F2 mm space group can be suggested from single crystal X-ray diffraction. A significant presence of Ba atoms in the [ M2O 2] slabs is confirmed in agreement with the previous works but specific Ba 2+ and Bi 3+ sites have to be considered due to the large difference in bounding requirement of these cations. Possible origins for the ferroelectric relaxor behavior of the Ba-based compound are discussed in view of the presented structural analyses.

  2. Orientación de láminas delgadas de (Pb, CaTiO3

    Directory of Open Access Journals (Sweden)

    Mendiola, J.

    1999-06-01

    Full Text Available Calcium modified PbTiO3 thin films have been prepared on platinized Si, MgO and SrTiO3 substrates. The films were deposited from a sol-gel solution with a concentration of 0.3 M and with a 10% excess of PbO. Two deposits of this solution on the substrates were made by spin-coating, crystallizing each of them by a Rapid Thermal Processing. The resulting films present a single (Pb,CaTiO3 perovskite phase. All the films are textured, but the films deposited on MgO and SrTiO3 show a preferred orientation in the polar direction of the perovskite. As a result of this orientation, pyroelectric coefficients were measured, without any poling, for the films on MgO and SrTiO3. Pyroelectric measurements indicate the application of these films in infrarred sensors.Se han preparado láminas delgadas de PbTiO3 modificado con calcio sobre substratos de Si, MgO y SrTiO3 electrodados con Pt. Las películas se depositaron a partir de una solución sintetizada por sol-gel, con concentración 0.3 M y con un 10 % en exceso de PbO. En cada lámina se hicieron dos depósitos de la solución sobre el substrato mediante la técnica de “spin-coating”, cristalizando cada uno de ellos con un tratamiento térmico rápido. Todas las láminas resultantes presentaban como única fase cristalina la perovskita de (Pb,CaTiO3. Las láminas presentaron una cierta textura, observándose una orientación preferente en la dirección polar en el caso de las películas depositas sobre MgO y SrTiO3. Como resultado de esta orientación, se midieron coeficientes piroeléctricos, sin polarización previa, en las láminas sobre MgO y SrTiO3. Las medidas piroeléctricas de estos materiales evidencian su utilidad en dispositivos para sensores de infrarrojo.

  3. Synthesis and electrical characterization of Ca2Nd4Ti6O20 ceramics

    Directory of Open Access Journals (Sweden)

    Muhammad Raz

    2016-03-01

    Full Text Available Ca2Nd4Ti6O20, a layered perov skite structured material was synthesized via a chemical (citrate sol-gel route for the first time using nitrates and alkoxide precursors. Phase analysis of a sample sintered at 1625 °C revealed the formation of an orthorhombic (Pbn21 symmetry. The microstructure of the sample after sintering comprised rod-shaped grains of a size of 1.5 to 6.5µm. The room temperature dielectric constant of the sintered sample was 38 at 100 kHz. The remnant polarization (Pr and the coercive field (Ec were about 400 μC/cm2 and 8.4 kV/cm, respectively. Impedance spectroscopy revealed that the capacitance (13.7 pF and activation energy (1.39 eV of the grain boundary was greater than the capacitance (5.7 pF and activation energy (1.13 eV of the grain.

  4. High temperature properties of manganese modified CaBi 4Ti 4O 15 ferroelectric ceramics

    Science.gov (United States)

    Zhang, Shujun; Kim, Namchul; Shrout, Thomas R.; Kimura, Masahiko; Ando, Akira

    2006-10-01

    The dielectric, piezoelectric and electromechanical properties of manganese modified CaBi 4Ti 4O 15 (CBT) bismuth layer-structured ferroelectric ceramics were determined in the range of room temperature to ˜800 ∘C. The room temperature dielectric permittivity and dielectric loss were found to be 148 and 0.2%, respectively. The piezoelectric coefficients, d33 and d15, were 14 pC/N and 9 pC/N, with electromechanical coupling factors k33'=8.4% and k15=5.5%. The mechanical quality factor Q (sliver extensional mode) was 4300 at room temperature, decreasing with increasing temperature. The remnant polarization and coercive field were found to be 5.2 μC/cm 2 and 88 kV/cm, respectively. The excellent piezoelectric, mechanical properties, together with its high Curie temperature (˜800 ∘C) and high electrical resistivity ( 1×107 Ω cm at 500 ∘C), demonstrated the potential of manganese modified CBT ceramics for ultra-high temperature sensing applications.

  5. Electrical anisotropy in the hot-forged CaBi 4Ti 4O 15 ceramics

    Science.gov (United States)

    Rout, S. K.; Hussain, A.; Sinha, E.; Ahn, C. W.; Kim, I. W.

    2009-06-01

    Textured CaBi 4Ti 4O 15 (CBT) ceramics have been fabricated via a hot-forging technique. The effect of grain orientation on the dielectric and electrical properties is studied by impedance ( Z∗) and modulus ( M∗) spectroscopy. The degree of orientation ( F) calculated from X-ray diffraction pattern is found to be 89.4% along the c-axis of the crystal structure. The permittivity was measured along both perpendicular and parallel directions of the forging axis. The ratio of permittivity along perpendicular to parallel direction is found to be ˜3 at the Curie temperature of 797 °C. The non-superimposition of the normalized Z″ and M″ vs. frequency plot revealed the conduction in the material is localized and deviate from ideal Debye behavior. The power law exponent n of the material has been explained on the basis of jump relaxation model and revealed the conduction through grain boundary. Activation energy ( Ea) is obtained from Arrhenius plots of the dc conductivity for both the ceramics and it is found to be 0.89 eV and 0.78 eV for CBT (∥) and CBT (⊥), respectively.

  6. Heteroepitaxial growth and interface structure of pyrochlore (Ca,Ti)2(Nb,Ti)2O7 thin films on (1 1 0) NdGaO3 substrates

    Science.gov (United States)

    Jin, Xiao-Wei; Chen, Yue-Hua; Lu, Lu; Mi, Shao-Bo; Jin, Lei; Jing, Hong-Mei; Wang, Hong; Jia, Chun-Lin

    2018-02-01

    Epitaxial thin films of (Ca,Ti)2(Nb,Ti)2O7 with pyrochlore structure have been successfully fabricated on orthorhombic (1 1 0) NdGaO3 substrates by a magnetron sputtering system. By analysis of selected-area electron diffraction patterns, the film-substrate orientation relationship is determined to be 〈0 0 1〉{1 0 0}film//[0 0 1](1 1 0)substrate. Atomic-scale structure investigations of the heterointerface by means of advanced electron microscopy reveal that a perovskite-type Ca(Ti,Nb)O3 layer with a thickness of several unit cells forms between the (Ca,Ti)2(Nb,Ti)2O7 films and the NdGaO3 substrates. The formation of the Ca(Ti,Nb)O3 layer results from the demand for accommodation of the crystal structure mismatching between the pyrochlore film and the perovskite-type substrate, which favors the epitaxial growth of the (Ca,Ti)2(Nb,Ti)2O7 films on the NdGaO3 substrates.

  7. Luminescence characterization of (Ca{sub 1-x}Sr{sub x})(S{sub 1-y}Se{sub y}):Eu{sup 2+},M{sup 3+} (M = Sc and Y) for high color rendering white LED

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jung-Sik; Kim, Hyun-Joon; Jeong, Yong-Kwang [Department of Chemistry, Chungnam National University, Gung-Dong Yusung-Goo, Daejeon 305-764 (Korea, Republic of); Kim, Kwang-Bok [Kumho Electric Inc., 64-1 Bongmyung-Ri, Namsa-Myun, Youngin, Gyeonggi-Do 449-883 (Korea, Republic of); Kang, Jun-Gill, E-mail: jgkang@cnu.ac.kr [Department of Chemistry, Chungnam National University, Gung-Dong Yusung-Goo, Daejeon 305-764 (Korea, Republic of)

    2011-04-15

    Research highlights: {yields} Highly efficient red phosphors (Ca{sub 1-x}Sr{sub x})(S{sub 1-y}Se{sub y}):Eu{sup 2+},M{sup 3+} (M = Sc and Y). {yields} Quantum yield is 11.8% for Sc{sup 3+}) and 11.7% for Y{sup 3+}. {yields} The phosphors were coated with MgO to overcome their weakness against moisture. {yields} White LEDs were fabricated by the red phosphors and YAG:Ce{sup 3+} with a blue chip. - Abstract: The highly efficient red phosphors (Ca{sub 1-x}Sr{sub x})(S{sub 1-y}Se{sub y}):Eu{sup 2+},M{sup 3+} (M = Sc and Y) were prepared, starting from CaCO{sub 3}, SrCO{sub 3}, Eu{sub 2}O{sub 3}, Sc{sub 2}O{sub 3}, Y{sub 2}O{sub 3}, S, and SeO{sub 2} with a flux, by a conventional solid-state reaction. The optimized red phosphors converted 11.8% (Sc{sup 3+}) and 11.7% (Y{sup 3+}) of the absorbed blue light into luminescence. These quantum values are much higher than Q = 3.0% of CaS:Eu{sup 2+}. For the fabrication of light-emitting diodes (LEDs), the prepared phosphors were coated with MgO from non-aqueous solution to overcome their weakness against moisture. White LEDs were fabricated by pasting the prepared red phosphors and the yellow YAG:Ce{sup 3+} phosphor on an InGaN blue chip ({lambda}{sub ems} = 446.5 nm). The incorporation of the red phosphor to the YAG:Ce{sup 3+} phosphor resulted in an improved color rendering index (Ra) from 70 to 80.

  8. Temperature and electric field stabilities of dielectric and insulating properties for c-axis-oriented CaBi4Ti4O15 films

    Science.gov (United States)

    Kimura, Junichi; Takuwa, Itaru; Matsushima, Masaaki; Yasui, Shintaro; Yamada, Tomoaki; Funakubo, Hiroshi

    2013-07-01

    Temperature and electric field dependencies of the dielectric and insulating properties of (001)-oriented epitaxial CaBi4Ti4O15 films grown on (100)cSrRuO3//(100)SrTiO3 substrates were investigated and compared with those of conventional (100)-oriented epitaxial (Ba0.3Sr0.7)TiO3 and SrTiO3 films. All films showed negative temperature dependency of the capacitance from 25 to 500 °C, and their changes were -18%, -83%, and -58% for CaBi4Ti4O15, (Ba0.3Sr0.7)TiO3, and SrTiO3 films, respectively. Smaller change of the capacitance against dc electric field was also observed for CaBi4Ti4O15 films. Moreover, the maximum leakage current density of CaBi4Ti4O15 films measured at ±100 kV/cm was below 10-3 A/cm2 up to 500 °C, which was smaller than those of (Ba0.3Sr0.7)TiO3 and SrTiO3 films. These results indicate that (001)-oriented CaBi4Ti4O15 films are a useful candidate as the capacitor material applicable for the high temperature use because of its high stability against temperature and an electric field as well as the good insulating characteristics.

  9. A hybrid surface arc discharge ion source to produce ultra pure Ca(+2) beams for (40)Ca(alpha,gamma)(44)Ti reaction studies at ISAC/TRIUMF.

    Science.gov (United States)

    Jayamanna, K; Vockenhuber, C

    2008-02-01

    ISAC is an accelerator facility primarily dedicated to astrophysical studies. Off-line and online ion sources provide up to 65 keV of stable and radioactive beams to the ISAC accelerators. Initial acceleration is done via a constant velocity radio frequency quadrupole that requires 2 keV/u. Then the beam is further accelerated to 1.5 MeVu at ISAC-I and 6.5 MeV/u at ISAC-II. To study radiative capture reactions relevant for astrophysics, the recoil mass spectrometer DRAGON was built in the experimental area. (40)Ca(alpha,gamma)(44)Ti is identified as one of the key reactions in supernovae to produce (44)Ti and is given highest priority. For this experiment, an ultrapure Ca(+2) beam was requested from the off-line ion source. Initial tests showed that, when using conventional ion sources, (40)Ar and (40)K are the impurities that are most difficult to eliminate. In order to overcome this problem, a new concept was needed and the hybrid surface arc discharge ion source was born. The hybrid surface ion source consists of a small surface ionizer and an arc discharge placed in a solenoid field. A very low ratio of (40)Ar/(40)Ca=8 x 10(-5) was achieved with this new source and the experiment was completed successfully. The source is described in detail and its performance is discussed in this article.

  10. PENGUKURAN NILAI DIELEKTRIK MATERIAL CALCIUM COPPER TITANAT ( CaCu3Ti4O12 MENGGUNAKAN SPEKTROSKOPI IMPEDANSI TERKOMPUTERISASI

    Directory of Open Access Journals (Sweden)

    Widodo Budi Kurniawan

    2017-05-01

    ABSTRACT   The measurement of the complex dielectric constant and the magnitude of the capacitor impedances of the ceramic materials Calcium Copper Titanate CaCu3Ti4O12 (CCTO with purity of 99% has been done by using the method of computerized impedance spectroscopy in the frequency range 5 kHz - 120 kHz. The highest dielectric constant of the material was found to be 745 at 5 kHz in the sample sintered 7000C and the highest impedance of capacitor occured in CCTO sample non sintered that is 150434Ω. The results showed that complex dielectric constant and impedance of the capacitor of the material under study was frequency dependent.   Keywords : impedance spectroscopy, CaCu3Ti4O12,complex dielectric constant and impedance of capacitor

  11. {110}-Layered B-cation ordering in the anion-deficient perovskite Pb2.4Ba2.6Fe2Sc2TiO13 with the crystallographic shear structure.

    Science.gov (United States)

    Tyablikov, O A; Batuk, D; Tsirlin, A A; Batuk, M; Verchenko, V Yu; Filimonov, D S; Pokholok, K V; Sheptyakov, D V; Rozova, M G; Hadermann, J; Antipov, E V; Abakumov, A M

    2015-06-21

    A novel anion-deficient perovskite-based compound, Pb(2.4)Ba(2.6)Fe(2)Sc(2)TiO(13), was synthesized via the citrate-based route. This compound is an n = 5 member of the AnBnO(3n-2) homologous series with unit-cell parameters related to the perovskite subcell a(p)≈ 4.0 Å as a(p)√2 ×a(p)× 5a(p)√2. The crystal structure of Pb(2.4)Ba(2.6)Fe(2)Sc(2)TiO(13) consists of quasi-2D perovskite blocks with a thickness of three octahedral layers separated by the 1/2[110](1[combining macron]01)(p) crystallographic shear (CS) planes, which are parallel to the {110} plane of the perovskite subcell. The CS planes transform the corner-sharing octahedra into chains of edge-sharing distorted tetragonal pyramids. Using a combination of neutron powder diffraction, (57)Fe Mössbauer spectroscopy and atomic resolution electron energy-loss spectroscopy we demonstrate that the B-cations in Pb(2.4)Ba(2.6)Fe(2)Sc(2)TiO(13) are ordered along the {110} perovskite layers with Fe(3+) in distorted tetragonal pyramids along the CS planes, Ti(4+) preferentially in the central octahedra of the perovskite blocks and Sc(3+) in the outer octahedra of the perovskite blocks. Magnetic susceptibility and Mössbauer spectroscopy indicate a broadened magnetic transition around T(N)∼ 45 K and the onset of local magnetic fields at low temperatures. The magnetic order is probably reminiscent of that in other AnBnO(3n-2) homologues, where G-type AFM order within the perovskite blocks has been observed.

  12. Propiedades dieléctricas de láminas delgadas de (Pb,CaTiO3 con alto contenido de Ca

    Directory of Open Access Journals (Sweden)

    Calzada, M. L.

    2004-04-01

    Full Text Available Lead titanate thin films modified with calcium, Pb1-xCaxTiO3, with x>35%, have been deposited onto Pt/TiO2/SiO2/(100Si y Pt/(100MgO substrates, by the sol-gel method and a rapid thermal processing (RTP. Properties similar to the counterpart bulk ceramics are planned, such as the decrease of the phase transition temperature and the increase of permittivity at room temperature. Films with Ca content close to 40 % and 50% exhibit at room temperature, high enough permittivity with reduced temperature dependence and a C-V behaviour that make them of interest for DRAM and high frequency devices.Se han preparado láminas delgadas de titanato de plomo modificado con calcio, Pb1-xCaxTiO3, (PTCa con x>35%, depositadas sobre substratos de Pt/TiO2/SiO2/(100Si y Pt/(100MgO, empleando la técnica de sol-gel y un horno rápido de procesado (RTP. Se intenta obtener propiedades cercanas al material cerámico masivo, como son la bajada de la temperatura de la transición ferro-paraeléctrica y el aumento de la permitividad, ε´ a temperatura ambiente. Así, se consiguen láminas de contenido de Ca próximas al 40% y 50% con valores altos de permitividad, poco dependientes de la temperatura, que presentan un alto carácter difuso en la transición para temperaturas próxima a ambiente y un comportamiento de la capacidad con el voltaje, C-V,que las hacen de interés en la fabricación de DRAM y dispositivos para alta frecuencia.

  13. Preparation, characterization and activity evaluation of CaZrTi{sub 2}O{sub 7} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shifu, E-mail: chshifu@chnu.edu.cn [Department of Chemistry, Huaibei Normal University, Anhui, Huaibei 235000 (China); Ji Mingsong; Yuang Yunguang; Liu Wei [Department of Chemistry, Huaibei Normal University, Anhui, Huaibei 235000 (China)

    2012-06-15

    CaZrTi{sub 2}O{sub 7} photocatalyst sample was prepared by a polymerizable complex method. The photocatalyst was characterized by X-ray powder diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence emission spectroscopy, Brunauer-Emmett-Teller analysis, N{sub 2} adsorption measurements, and terephthalic acid probed fluorescence technique. The photocatalytic activity of the sample was evaluated by photocatalytic oxidation of methyl orange and photocatalytic reduction of Cr{sub 2}O{sub 7}{sup 2-} and nitrobenzene. The results showed that when the reaction solution was illuminated by UV light for 50 min, the photooxidation efficiency of methyl orange and the photoreduction efficiency of Cr{sub 2}O{sub 7}{sup 2-} were 83.1% and 87.9%, respectively. When methanol was used as the holes scavengers and the illumination time was 10 h in the photocatalytic reduction experiment of nitrobenzene, the production efficiency of aniline was 70.3%. The effect of the heat treatment conditions on the photocatalytic activity was also investigated. The optimum preparation condition for CaZrTi{sub 2}O{sub 7} sample is 800 Degree-Sign C for 12 h. The mechanisms of influence on the photocatalytic activity of the sample were also discussed with the valance band theory. - Highlights: Black-Right-Pointing-Pointer CaZrTi{sub 2}O{sub 7} photocatalyst was prepared by a polymerizable complex method. Black-Right-Pointing-Pointer The heat treatment has a significant influence on the photocatalytic activity. Black-Right-Pointing-Pointer The optimal heat treatment condition is approximately 800 Degree-Sign C for 12 h. Black-Right-Pointing-Pointer The CaZrTi{sub 2}O{sub 7} has the band bap of about 2.89 eV with particle size of about 80 nm.

  14. Potential new solid oxide fuel cell (SOFC) anode materials in the La-Ca-Cr-Ti-Ru-O system

    Energy Technology Data Exchange (ETDEWEB)

    Vashook, V.; Ullmann, H. [Institute of Physical Chemistry and Electrochemistry, Dresden University of Technology, D-01062 Dresden (Germany); Zosel, J. [Kurt-Schwabe Institute for Measurements and Sensor Technology Meinsberg, D-04720, Ziegra-Knobelsdorf (Germany); Mueller, R.; Vasylechko, L. [National University Lviv Polytechnic, 12 Bandera St., Lviv 79013 (Ukraine); Shuk, P.; Guth, U. [Institute of Physical Chemistry and Electrochemistry, Dresden University of Technology, D-01062 Dresden (Germany); Kurt-Schwabe Institute for Measurements and Sensor Technology Meinsberg, D-04720, Ziegra-Knobelsdorf (Germany)

    2006-07-15

    Six single phase La{sub 1-x}Ca{sub x}Cr{sub 1-y}Ti{sub y-{gamma}}Ru{sub {gamma}}O{sub 3-{delta}} (x = 0.1, 0.2, y = 1.0, 0.8 and {gamma} = 0.0, 0.1, 0.2) compositions are prepared by solid state reaction. Oxygen non-stoichiometry, electrical conductivity, catalytic activity, and electrochemical efficiency of these compositions is investigated over a wide temperature and oxygen partial pressure range. The compositions with the highest electrical conductivity (50 S cm{sup -1}) at reducing conditions and highest catalytic activity for the oxidation of hydrocarbons are found. A combination of highly conductive La{sub 1-x}Ca{sub x}TiO{sub 3-{delta}} in a reducing atmosphere and an intermediate functional film of catalytically active La{sub 0.1}Ca{sub 0.9}Ti{sub 1-x}Ru{sub x}O{sub 3-{delta}} for the oxidation of hydrocarbons could potentially be very useful in a multilayer SOFC anode. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  15. Temperature Dependence of Piezoelectric Properties of Grain-Oriented CaBi4Ti4O15 Ceramics

    Science.gov (United States)

    Ogawa, Hirozumi; Kimura, Masahiko; Ando, Akira; Sakabe, Yukio

    2001-09-01

    Piezoelectric properties of grain-oriented bismuth layer structured compound CaBi4Ti4O15 ceramics and their temperature dependencies were studied. The grain-oriented CaBi4Ti4O15 ceramics were fabricated by the templated grain growth method. The highly preferentially (00l) oriented CaBi4Ti4O15 ceramics were obtained and their Lotgering (00l) orientation degree was almost 100%. The electromechanical coupling coefficient of the longitudinal vibration mode (k33) was approximately three times as large as that of the nonoriented specimen, and the temperature coefficient of resonant frequency (|fr-TC|) was the same as that of the nonoriented specimen. The 24 vibration mode is separated from the 15 vibration mode in the thickness shear vibration of the grain-oriented ceramics. The electromechanical coupling coefficient k15 of the grain-oriented specimen was twice as large as k15 of the nonoriented ceramics, while, k24 was one-third that of k15 of the nonoriented specimen. The |fr-TC| of the 15 vibration mode of the grain-oriented specimen was half that of the 15 vibration mode in the nonoriented ceramics, and that of the 24 vibration mode of the oriented specimen was much larger than that of the 15 vibration mode in the nonoriented ceramics.

  16. Red emission in Pr doped CaBi{sub 4}Ti{sub 4}O{sub 15} ferroelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Peng Dengfeng, E-mail: pengdengfeng1984@163.com [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Sun Haiqin [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Wang Xusheng, E-mail: xs-wang@tongji.edu.cn [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Zhang Juncheng; Tang Mianmian; Yao Xi [Functional Materials Research Laboratory, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2011-11-15

    In this paper, Pr doped CaBi{sub 4}Ti{sub 4}O{sub 15} ceramics were prepared by a traditional solid state method. Crystal structure and morphologies of the ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photoluminescence properties of the samples were investigated by a spectrofluorometer. Three excitation bands are located at wide range of wavelength, which are 300-430 nm, 440-510 nm and 550-570 nm respectively. Upon the excitation of 494 nm light, the samples shows an emission peak centered at 614 nm, corresponding to {sup 1}D{sub 2} {yields} {sup 3}H{sub 4} transition. A 614 nm red emission excited under the wave with long wavelength of Pr doped CaBi{sub 4}Ti{sub 4}O{sub 15} makes it useful in the white LEDs. In addition, it is an intrinsic ferroelectric and piezoelectric material; the enhanced ferroelectric properties were obtained by Pr doping. As a multifunctional materials, Pr doped CaBi{sub 4}Ti{sub 4}O{sub 15} may be useful in white LEDs, sensor, and optical-electro integration.

  17. Enhanced luminescence in Mg2+ codoped CaTiO3:Eu3+ phosphor prepared by solid state reaction

    Science.gov (United States)

    Vandana, C. Sai; Rudramadevi, B. Hemalatha

    2016-05-01

    CaTiO3 phosphors doped with Eu3+ and codoped with Mg2+ were prepared by Solid State Reaction method. The powders were characterized by X-ray diffraction, SEM with EDS, Raman scattering, and photoluminescence spectroscopy. The Crystalline phase and vibrational modes of the phosphors were studied using XRD pattern and Raman Spectrum respectively. The morphological studies of the phosphor samples were carried out using SEM analysis. From PL spectra we have observed two prominent red emission peaks around at 595 nm (5D0→7F1), 619 nm (5D0→7F2) with the excitation of 399nm for Eu3+ doped CaTiO3 powders. The PL intensity of CaTiO3:Eu3+ phosphor is enhanced significantly on codoping with Mg2+. The observed enhanced emissions are due to energy transfer from Mg2+ to Eu3+, which is due to radiative recombination. Eu3+ doped phosphors are well known to be promising materials for electroluminescent devices, optical amplifiers, and lasers.

  18. Enhanced ferroelectric properties of predominantly (100)-oriented CaBi4Ti4O15 thin films on Pt /Ti/SiO2/Si substrates

    Science.gov (United States)

    Yan, Jing; Hu, Guangda; Liu, Zongming; Fan, Suhua; Zhou, Ying; Yang, Changhong; Wu, Weibing

    2008-03-01

    Predominantly (100)-oriented CaBi4Ti4O15 (CBTi) films were fabricated on Pt (111)/Ti /SiO2/Si substrates using a metal organic decomposition method at annealing temperatures ranging from 600to800°C. The growth mode of the predominantly (100)-oriented CBTi films fabricated by the sequential layer annealing method was discussed based on the structure evolution with the annealing temperature. The remanent polarization and coercive field of the CBTi film annealed at 750°C are 38.1μC/cm2 and 216kV/cm, respectively. No fatigue can be observed after 109 switching cycles. The remanent polarization of the purely a-axis-oriented CBTi film should be higher than 50μC/cm2.

  19. A -Site Ordered Double Perovskite CaMnTi 2 O 6 as a Multifunctional Piezoelectric and Ferroelectric–Photovoltaic Material

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Gaoyang [Frontier Institute; Charles, Nenian [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States; Shi, Jing [MOE Key Laboratory; Rondinelli, James M. [Department; Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

    2017-09-11

    The double perovskite CaMnTi2O6, is a rare A site ordered perovskite oxide that exhibits a sizable ferroelectric polarization and relatively high Curie temperature. Using first-principles calculations combined with detailed symmetry analyses, we identify the origin of the ferroelectricity in CaMnTi2O6. We further explore the material properties of CaMnTi2O6, including its ferroelectric polarization, dielectric and piezoelectric responses, magnetic order, electronic structure, and optical absorption coefficient. It is found that CaMnTi2O6 exhibits room-temperature-stable ferroelectricity and moderate piezoelectric responses. Moreover, CaMnTi2O6 is predicted to have a semiconducting energy band gap similar to that of BiFeO3, and its band gap can further be tuned-via distortions of the planar Mn-O bond lengths. CaMnTi2O6 exemplifies a new class of single-phase semiconducting ferroelectric perovskites for potential applications in ferroelectric photovoltaic solar cells.

  20. Application and bioactive properties of CaTI, a trypsin inhibitor from Capsicum annuum seeds: membrane permeabilization, oxidative stress and intracellular target in phytopathogenic fungi cells.

    Science.gov (United States)

    Silva, Marciele S; Ribeiro, Suzanna Ff; Taveira, Gabriel B; Rodrigues, Rosana; Fernandes, Katia Vs; Carvalho, André O; Vasconcelos, Ilka Maria; Mello, Erica Oliveira; Gomes, Valdirene M

    2017-08-01

    During the last few years, a growing number of antimicrobial peptides have been isolated from plants and particularly from seeds. Recent results from our laboratory have shown the purification of a new trypsin inhibitor, named CaTI, from chilli pepper (Capsicum annuum L.) seeds. This study aims to evaluate the antifungal activity and mechanism of action of CaTI on phytopathogenic fungi and detect the presence of protease inhibitors in other species of this genus. Our results show that CaTI can inhibit the growth of the phytopathogenic fungi Colletotrichum gloeosporioides and C. lindemuthianum. CaTI can also permeabilize the membrane of all tested fungi. When testing the inhibitor on its ability to induce reactive oxygen species, an induction of reactive oxygen species (ROS) and nitric oxide (NO) particularly in Fusarium species was observed. Using CaTI coupled to fluorescein isothiocyanate (FITC), it was possible to determine the presence of the inhibitor inside the hyphae of the Fusarium oxysporum fungus. The search for protease inhibitors in other Capsicum species revealed their presence in all tested species. This paper shows the antifungal activity of protease inhibitors such as CaTI against phytopathogenic fungi. Antimicrobial peptides, among which the trypsin protease inhibitor family stands out, are present in different species of the genus Capsicum and are part of the chemical arsenal that plants use to defend themselves against pathogens. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Tuning of Photoluminescence by Cation Nanosegregation in the (CaMg) x (NaSc) 1–x Si 2 O 6 Solid Solution

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhiguo; Liu, Guokui; Wen, Jianguo; Mei, Zhigang; Balasubramanian, Mahalingam; Molokeev, Maxim S.; Peng, Licong; Gu, Lin; Miller, Dean J.; Liu, Quanlin; Poeppelmeier, Kenneth R.

    2016-02-03

    Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1-xSi2O6 (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si2O6 and (NaSc)Si2O6 contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.

  2. Investigation of laser cladding high temperature anti-wear composite coatings on Ti6Al4V alloy with the addition of self-lubricant CaF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Zhan-Feng [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Liu, Xiu-Bo, E-mail: liuxiubo@suda.edu.cn [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Ren, Jia; Luo, Jian; Shi, Shi-Hong; Chen, Yao [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Shi, Gao-Lian; Wu, Shao-Hua [Suzhou Institute of Industrial Technology, Suzhou 215104 (China)

    2014-09-15

    Highlights: • A novel high temperature self-lubricating wear-resistant coating was fabricated. • TiC carbides and self-lubricant CaF{sub 2} were “in situ” synthesized in the coating. • The coating with the addition of CaF{sub 2} possessed superior properties than without. - Abstract: To improve the high-temperature tribological properties of Ti–6Al–4V alloy, γ-NiCrAlTi/TiC and γ-NiCrAlTi/TiC/CaF{sub 2} coatings were fabricated on Ti–6Al–4V alloy by laser cladding. The phase compositions and microstructure of the coatings were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The tribological behaviors were evaluated using a ball-on-disk tribometer from ambient temperature to 600 °C under dry sliding wear conditions and the corresponding wear mechanisms were discussed. The results indicated that the γ-NiCrAlTi/TiC/CaF{sub 2} coating consisted of α-Ti, the “in situ” synthesized TiC block particles and dendrite, γ-NiCrAlTi solid solution and spherical CaF{sub 2} particles. The wear rates of γ-NiCrAlTi/TiC/CaF{sub 2} coating were decreased greatly owing to the combined effects of the reinforced carbides and continuous lubricating films. Furthermore, the friction coefficients of γ-NiCrAlTi/TiC/CaF{sub 2} coating presented minimum value of 0.21 at 600 °C, which was reduced by 43% and 50% compared to the substrate and γ-NiCrAlTi/TiC coating respectively. It was considered that the γ-NiCrAlTi/TiC/CaF{sub 2} coating exhibited excellent friction-reducing and anti-wear properties at high temperature.

  3. Structure and electrical properties of intergrowth bismuth layer-structured Bi4Ti3O12-CaBi4Ti4O15 ferroelectric ceramics

    Science.gov (United States)

    Choi, Gi Ppeum; Cho, Sam Yeon; Bu, Sang Don

    2016-09-01

    Pb-free ferroelectric Bi4Ti3O12-CaBi4Ti4O15 (BIT-CBT) ceramics were manufactured using a solid-state reaction method. Structural analysis by using X-ray diffraction confirmed the presence of a second phase of Bi2Ti2O7, and the surface depth X-ray diffraction analysis revealed that this phase existed only on the surface. This second phase appears to have been caused by the volatilization of Bi ions at high sintering temperatures. For resolution of the issue of volatilization of Bi ions and manufacture of BIT-CBT ceramics with a single phase, Bi2O3 powder was added to the BIT-CBT mixture, and a powder-bed method, in which pellets were covered with BIT-CBT powder, was used to manufacture the ceramic. The piezoelectric coefficient of the single-phase BIT-CBT ceramics was 12.4 pC/N while the residual polarization and the coercive electric field were 11.3 μC/cm2, and 125 kV/cm, respectively. The results suggest that single-phase BIT-CBT ceramics are suitable for the manufacture of elements incorporating these electrical characteristics.

  4. A new SrBi4Ti4O15/CaBi4Ti4O15 thin-film capacitor for excellent electric stability.

    Science.gov (United States)

    Noda, Minoru; Nomura, Shuhei; Uchida, Hiroshi; Yamashita, Kaoru; Funakubo, Horoshi

    2012-09-01

    SrBi(4)Ti(4)O(15) (SBTi) and CaBi(4)Ti(4)O(15) (CBTi) dielectric films of bismuth layered-structure dielectrics (BLSD) are prepared on Pt(100) film for constructing stacked-type dielectric capacitors; it is observed that they are c-axis singleoriented crystalline films. Compared with the perovskite barium titanate family of (Ba,Sr)TiO(3) (BST), it is observed that the SBTi film keeps a low leakage of 10(-7) A/cm(2) at 250 kV/ cm, which is smaller by an order of magnitude than the BST film, even with thinner SBTi film. The temperature coefficient of capacitance (TCC) of the SBTi or CBTi film is about 100 to 250 ppm/K and is much smaller than that of the perovskite BST film. Because the SBTi and CBTi films have opposite polarities of TCC in this experiment, they are expected to cancel out the temperature dependence in the SBTi/CBTi composite capacitor. These results indicate that the BLSD films of SBTi and CBTi are effective for application in high-temperature and high-permittivity capacitors with the practical barium perovskite oxide family.

  5. Laser surface treatment for porous and textured Ca-P bio-ceramic coating on Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Paital, Sameer R; Dahotre, Narendra B [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2007-12-15

    In the present paper the feasibility of depositing a porous calcium phosphate (CaP) bio-ceramic coating using a continuous wave Nd:YAG laser on a Ti-6Al-4V substrate has been demonstrated. The advantages offered by such porous bio-ceramic coating are its inertness combined with the mechanical stability of the highly convoluted interface that develops when bone grows into the pores of ceramic. The formation of different phases with varying laser fluences is studied using x-ray diffraction (XRD). A quantitative estimation of the crystallite size and relative amounts of Ti and other predominant phases such as TiO{sub 2} and {alpha}-tricalcium phosphate ({alpha}-TCP) were obtained. An increase in the crystallite size with increasing laser fluence is observed for all the above three phases. It is observed that TiO{sub 2} is the predominant phase for all laser fluences and there is an increase in the {alpha}-TCP phase with increasing laser fluence. Surface porosity measurements indicated a decreasing trend with increasing laser fluence. Microhardness measurements in the cross section of samples showed a maximum hardness within the coating. The bioactivity of the coatings was further demonstrated by the formation of an apatite-like layer on the surface of the sample after being immersed in a simulated biofluid.

  6. Fabrication and evaluation of a pulse laser-induced Ca-P coating on a Ti alloy for bioapplication

    Energy Technology Data Exchange (ETDEWEB)

    Paital, Sameer R; Dahotre, Narendra B [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Balani, Kantesh; Agarwal, Arvind, E-mail: ndahotre@utk.ed [Department of Mechanical and Materials Engineering, Florida International University, EAS 3400, Miami, FL 33174 (United States)

    2009-02-15

    In the present paper, we demonstrate the feasibility of depositing a tailored calcium phosphate (Ca-P) coating on a Ti-6Al-4V substrate by using a pulsed Nd:YAG laser system. Different textures were obtained by varying the laser spot overlap with change in laser traverse speed. Surface roughness measurements using laser confocal microscopy indicated a decrease in roughness with increasing laser scan speed. X-ray diffraction studies revealed the formation of alpha-TCP, TiO{sub 2}, Ti and Al as the major phases. An instrumented nanoindenation technique used to study the mechanical properties of the coatings, revealed a very high hardness and Young's modulus of the coating surface as compared to the substrate. This further proved the retainment of the ceramic phase on the surface. Wear studies in a simulated biofluid (SBF) environment demonstrated an increased wear resistance of the coated samples as compared to the bare Ti-6Al-4V. Formation of an apatite-like layer after immersion in SBF for different time periods further demonstrated the bioactivity of the coated samples.

  7. Piezoelectric Properties of CaBi4Ti4O15 Ferroelectric Thin Films Investigated by Atomic Force Microscopy

    Science.gov (United States)

    Fu, Desheng; Suzuki, Kazuyuki; Kato, Kazumi

    2003-09-01

    Atomic force microscopy (AFM) is used to probe the local piezoelectric properties of CaBi4Ti4O15 (CBT) bismuth-layer-structured ferroelectric thin films. Calibration with Z-cut LaTiO3 and X-cut quartz crystals shows that a conductive AFM tip can be employed as a top electrode to accurately evaluate the piezoelectric displacement in ferroelectric materials without a top electrode. Our measurements on individual grains in CBT film clearly reveal that the local piezoelectric properties are determined by the polarization state in the grain. In a grain with a polar axis very close to the normal direction, a piezoelectric coefficient of 16 pm/V was attained after poling.

  8. Unidirectionally Textured CaBi4Ti4O15 Ceramics by the Reactive Templated Grain Growth with an Extrusion

    Science.gov (United States)

    Takeuchi, Tsuguto; Tani, Toshihiko; Saito, Yasuyoshi

    2000-09-01

    Dense CaBi4Ti4O15 (CBT) ceramics with a unique texture were prepared by the reactive templated grain growth (RTGG) method using an extrusion technique. Plate-like Bi4Ti3O12 (BIT) particles, a reactive template for CBT, were mixed with other oxide and carbonate powders and unidirectionally aligned by extrusion. During sintering, oriented CBT grains were formed in situ topotaxially on the oriented BIT particles, and the templated grain growth and their densification eventually fabricated textured CBT ceramics. X-ray diffraction measurements and scanning electron microscopic observations revealed that the plate-like CBT grains were unidirectionally oriented parallel to the extruding direction without uniaxial alignment. Textured CBT ceramics poled in the extruding direction exhibited electromechanical coupling coefficients (k33) and piezoelectric coefficients (d33 and g33) more than two times as large as one of nontextured ceramics with the same composition.

  9. Preparation and characterizations of Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} by complex polymerization method (CPM)

    Energy Technology Data Exchange (ETDEWEB)

    Motta, F.V. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, CMDMC, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil)], E-mail: fabiana@liec.ufscar.br; Marques, A.P.A. [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Escote, M.T. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil); Melo, D.M.A. [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Ferreira, A.G. [Laboratorio de Ressonancia Magnetica Nuclear, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Longo, E. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil); Leite, E.R. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, CMDMC, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Varela, J.A. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil)

    2008-10-06

    Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} (BCT) was prepared by the complex polymerization method (CPM) using Ba{sub 0.8}Ca{sub 0.2}CO{sub 3} and [Ti[OCH(CH{sub 3}){sub 2}]{sub 4} as starting materials. The powders were crystallized at several temperatures from 400 to 1200 deg. C using different times (from 1 to 8 h). The phase evolution and the physical properties were characterized by X-ray diffraction, Raman and IR spectroscopy. Such results indicate that the precursor Ba{sub 0.8}Ca{sub 0.2}CO{sub 3} used in the synthesis of Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} promotes an effective complexation of the ions Ca{sup 2+} in the matrix of BaTiO{sub 3}. After heat treatment for 2 h at 600 deg. C the phase BCT was obtained with absence of the CaTiO{sub 3} or BaCO{sub 3} phases. The CPM is an efficient method in the synthesis of the BCT, using small reaction time and low temperature and cost for the preparation of these powders.

  10. Detector de IR de lámina ferroeléctrica de (Pb,Ca)TiO3

    OpenAIRE

    Ramos, Pablo; Mendiola, J.; Jiménez, Ricardo; Calzada, M L; González, A; Tejedor, Paloma

    2002-01-01

    [ES] Se han obtenido depósitos multicapa de titanato de plomo modificado con calcio, (Pb0.76Ca0.24)TiO3, mediante un método de sol-gel, sobre substratos de Pt/MgO(100). El tratamiento térmico del substrato y la cristalización de las multicapas mediante tasas de calentamiento rápidas causan el desarrollo de una importante orientación preferente según el eje polar, perpendicular al mismo, lo que supone una autopolarización muy rentable para su empleo en detectores piroeléctricos de ra...

  11. Synthesis and characterization of CaBi 4Ti 4O 15 thin films annealed by microwave and conventional furnaces

    Science.gov (United States)

    Simões, A. Z.; Riccardi, C. S.; Ramírez, M. A.; Cavalcante, L. S.; Longo, E.; Varela, J. A.

    2007-08-01

    CaBi 4Ti 4O 15 thin films were deposited by the polymeric precursor method and crystallized in a domestic microwave oven and conventional furnace. The films obtained for microwave energy are well-adhered, homogeneous and with good specularity when treated at 700 °C for 10 min. The microstructure and the structure of the films can be tuned by adjusting the crystallization conditions. When microwave oven is employed, the films presented bigger grains with mean grain size around 80 nm. For comparison, films were also prepared by the conventional furnace at 700 °C for 2 h.

  12. High piezoelectric response in polar-axis-oriented CaBi4Ti4O15 ferroelectric thin films

    Science.gov (United States)

    Fu, Desheng; Suzuki, Kazuyuki; Kato, Kazumi

    2004-10-01

    We report on the piezoelectric properties of polar-axis-oriented CaBi4Ti4O15 films detected by atomic force microscope (AFM). The sol-gel-derived films onto Pt foil show excellent switching properties, and can be uniformly polarized over large areas with a conductive AFM tip. The films have an extremely high piezoelectric coefficient of d33, and a value of 180pm /V has been detected. These results indicate that the oriented bismuth-layered films can be used as the lead-free piezoelectrics.

  13. Trapping of oxygen vacancies on twin walls of CaTiO sub 3 : a computer simulation study

    CERN Document Server

    Calleja, M; Salje, E K H

    2003-01-01

    We have studied the atomic structure of [001] 90 deg. rotation twin walls in orthorhombic CaTiO sub 3 (symmetry Pbnm) at low temperature (10 K) and their effects on oxygen vacancies. The wall thickness was found to be 2.3 nm at T || T sub c and it was found that it is energetically favourable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an oxygen vacancy in the wall with respect to the bulk is calculated to be <= 1.2 eV.

  14. N = 3 - 3 Transitions of Ne-like Ions in the Iron Group, Especially Ca(10+) and Ti(12+)

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Y; Encarnacion, J L; Trabert, E

    2008-10-09

    The Ti XIII 2s{sup 2}2p{sup 5}3l-3l{prime} and 2s2p{sup 6}3l-3l{prime} transitions that have been discussed previously on the basis of beam-foil spectra and laser-produced plasmas in comparison to semi-empirically scaled computations have now been treated by accurate ab initio Multi-reference Moller-Plesset calculations. While most 2s{sup 2}2p{sup 5}3l-3l{prime} line identifications are supported by the new calculations, the 2s2p{sup 6}3l-3l{prime} transition arrays are revised. Theoretical level positions are given for all elements from Ca through Fe. The quality of the calculation is demonstrated on the beam-foil spectra of Ca.

  15. Electronic structures and effective masses of photogenerated carriers of CaZrTi2O7 photocatalyst: First-principles calculations

    Science.gov (United States)

    Liu, Jianjun; Chen, Shifu; Zhu, Yongfa

    2012-09-01

    The band structures, density of states and effective masses of photogenerated carriers for CaZrTi2O7 photocatalyst were performed using first principles method with the virtual crystal approximation. The results indicated that CaZrTi2O7 has an indirect band gap of about 3.25 eV. The upper valence bands of CaZrTi2O7 are formed by O 2p states mixed with Ti 3d states, Zr 4d, 4p and 5s states, while the conduction bands are dominated by Ti 3d states, Zr 4d states and O 2p states. The calculated valence bands maximum (VBM) potential is located at 2.60 V (vs. normal hydrogen electrode (NHE)), while the conduction bands minimum (CBM) potential at -0.65 V. Therefore, CaZrTi2O7 has the ability to split water to hydrogen and oxygen under UV light irradiation. The calculated minimum effective mass of electron in CBM is about 1.35 m0, and the minimum effective mass of hole in VBM is about 1.23 m0. The lighter effective masses facilitate the migration of photogenerated carriers and improve photocatalytic performance.

  16. A-Site (MCe) Substitution Effects on the Structures and Properties of CaBi4Ti4O15 Ceramics

    Science.gov (United States)

    Yan, Haixue; Li, Chengen; Zhou, Jiaguang; Zhu, Weimin; He, Lianxin; Song, Yuxin

    2000-11-01

    We investigated the effect of A-site compound substitution on the structures and properties of Ca0.8(MCe)0.1Bi4Ti4O15 (M denotes Li, Na and K) ceramics. The samples were prepared by the conventional ceramic technique. Sintering characteristics of Ca0.8(MCe)0.1Bi4Ti4O15 and CaBi4Ti4O15 ceramics were discussed. X-ray powder diffraction patterns of the three modified CBT-based compounds show a single phase of bismuth oxide layer type structure with m=4. The hysteresis loops of polarization versus electric field of the four compounds were also measured. A-site compound substitution improves the piezoelectric properties and the high-temperature resistivity of these materials. A-site (LiCe) and (KCe) substitution not only improves the Curie temperature but also decreases the temperature coefficient of dielectric constant (TK\\varepsilon). Among the three modified ceramics, only the Curie temperature of Ca0.8(NaCe)0.1Bi4Ti4O15 is lower than that of CaBi4Ti4O15; however, its TK\\varepsilon is the lowest. As a result, all the three modified CBT-based ceramics were found to be excellent high-temperature piezoelectric materials.

  17. Synthesis and characterization of CCTO (CaCu{sub 3}Ti{sub 4}O{sub 12})

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, T.S.M.; Silva, M.A.S. da; Simao, S.H.C.; Silva, C.C.; Sombra, A.S.B., E-mail: supersainara@yahoo.com.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Sales, J.C. [Universidade Estadual Vale do Acarau (UVA), Sobral, CE (Brazil)

    2011-07-01

    The objective of this work is to study the ceramic material CCTO (CaCu{sub 3}Ti{sub 4}O{sub 12}) by X-Ray Diffraction. The CCTO is a material with a giant dielectric constant at room temperature and good temperature stability over a wide temperature and frequency ranges. The preparation method has a great influence on the structure and dielectric properties of this material. The CCTO was prepared by solid state method in a planetary high energy ball milling (Fritsch Pulverisette 5). Stoichiometric quantities of CaCO{sub 3} (Aldrich 99%), TiO{sub 2} (Merck 99%) and CuO (Analar 98%) were dry milled during 30h with a rotational speed of 370 rpm and then calcined at 1050 deg C for 12h. After, the CCTO was studied by X-ray diffraction (XRD). The refinement showed that the CCTO was formed with 100% mass, the graph of Williamson-Hall showed a homogeneous sample, with a contraction in the crystal lattice and a reasonably small particle size. (author)

  18. Comportamiento dieléctrico de cerámicos de CaCu3Ti4O12

    Directory of Open Access Journals (Sweden)

    Castro, M. S.

    2011-08-01

    Full Text Available In this work, CaCu3Ti4O12 (CCTO ceramics were prepared by solid state reaction at 900°C for 12 h and sintered at 1100°C during 3 h. The main phase detected through X-ray diffraction (XRD was CCTO. Also, by means of Raman spectroscopy, it was observed a secondary phase rich in CuO. A dielectric constant higher than 13.000ε0 was obtained by Impedance spectroscopy measurements in the range between 25 to 106Hz. The value could be explained by the effect of dipolar and space charge polarization processes.En este trabajo se prepararon cerámicos basados en CaCu3Ti4O12 (CCTO por reacción en estado sólido a 900°C y posterior sinterizado a 1100°C. Mediante difracción de rayos X (DRX se comprobó la presencia de CCTO. A través de espectroscopía Raman se observó la presencia de una fase secundaria rica en CuO. Las mediciones de espectroscopía de impedancia demostraron que este material presenta una constante dieléctrica mayor a 13.000ε0 en el intervalo comprendido entre 25 y 106 Hz. Este valor es atribuido a la presencia de mecanismos de polarización de carga espacial y dipolar.

  19. Efficient Solar Energy Conversion Using CaCu3Ti4O12 Photoanode for Photocatalysis and Photoelectrocatalysis

    Science.gov (United States)

    Kushwaha, H. S.; Madhar, Niyaz A; Ilahi, B.; Thomas, P.; Halder, Aditi; Vaish, Rahul

    2016-01-01

    A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm2, indicating the visible light induced photocatalytic ability of CCTO. Visible light mediated photocatalytic and photoelectrocatalytic degradation efficiency of CaCu3Ti4O12 pellets (CCTO) was investigated for three classes of pharmaceutical waste: erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid). It is found that the degradation process follows first order kinetic reaction in electrocatalysis, photocatalysis and photoelectrocatalysis and high kinetic rate constant was observed in photoelectrocatalysis. This was quite high in comparison to previously reported methods. PMID:26725655

  20. Synthesis and photocatalytic characterisation of mesoporous TiO2 films doped with Ca, W and N

    Directory of Open Access Journals (Sweden)

    Yolanda Castro

    2015-01-01

    Full Text Available Mesoporous TiO2 films doped with Ca2+, W6+ and nitrogen were obtained by sol-gel method using dip-coating procedure onto glass-slides in order to study the influence of dopants in their textural properties and photocatalytic activity. Titania sols were synthesized with and without dopants using titanium isopropoxide as titanium precursor, two complexing agents, acetic acid and acetyl acetone, and two pore generating agents, Pluronic F-127 (F127 and polyethylene glycol hexadecyl ether (Brij58. Films were characterised by Fourier Transform Infrared Spectroscopy (FTIR, Grazing X-ray diffraction (GXRD and Transmission Electron Microscopy (TEM. Environmental Ellipsometric Porosimetry (EEP permitted to obtain the adsorption/desorption isotherms and total pore volume, and to determine the porous size distribution and specific surface area (Ss of the films. The photocatalytic activity was evaluated through the degradation of methyl orange (MO in aqueous solution under UV light exposure. The photocatalytic activity depends on the nature of dopants, which affect the TiO2-anatase crystallite size and the textural properties of the final material. The best results of MO degradation were obtained for the films doped with Ca2+, this being correlated with the pore size and specific surface area of the films besides the dopant-effect on the photocatalytic mechanisms.

  1. Structure, Ferroelectric and Photoluminescence Properties of Eu-Doped CaBi4Ti4O15 Multifunctional Ceramics

    Science.gov (United States)

    Wu, Xiaochun; Xiao, Ping; Guo, Yongquan; Zheng, Qiaoji; Lin, Dunmin

    2015-10-01

    Lead-free multifunctional ceramics of CaBi4- x Eu x Ti4O15 were prepared by a traditional solid state method, and the effects of Eu doping on structure, ferroelectric, piezoelectric and photoluminescence properties of the ceramics were investigated. All the ceramics possessed typical bismuth layer structure with m = 4, belonging to orthorhombic symmetry, and no secondary phase was detected. The plate-like grains were observed in all the ceramics, and the grain growth was slightly inhibited after the addition of Eu. Saturated polarization hysteresis loops were observed for all the ceramics, and the remanent polarization P r decreased with Eu doping. The Eu-doped ceramics had a sharp excitation band centered at 465 nm due to the f-f transition from the 7F0 ground state to the 5D2 excited state of Eu3+. Under the excitation by 465 nm light, the main emission peaks located at 595 nm and 616 nm were obtained, which corresponds to the transition of 5D0-7F1, 5D0-7F2 levels in Eu3+, respectively. Our study shows that CaBi4Ti4O15 ceramics may be a promising multifunctional material for potential applications in optical-electro integration devices.

  2. Probing charge transfer in a novel class of luminescent perovskite-based heterostructures composed of quantum dots bound to RE-activated CaTiO3 phosphors

    Science.gov (United States)

    Lewis, Crystal S.; Liu, Haiqing; Han, Jinkyu; Wang, Lei; Yue, Shiyu; Brennan, Nicholas A.; Wong, Stanislaus S.

    2016-01-01

    We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite building blocks were created by a multi-pronged synthetic strategy involving molten salt and hydrothermal protocols. Subsequently, optical characterization of these heterostructures indicated a clear behavioral dependence of charge transfer in these systems upon a number of parameters such as the nature of the dopant, the reaction temperature, and particle size. Specifically, 2.7 nm diameter ligand-functionalized CdSe QDs were anchored onto sub-micron sized CaTiO3-based spherical assemblies, prepared by molten salt protocols. We found that both the Pr- and Eu-doped CaTiO3 displayed pronounced PL emissions, with maximum intensities observed using optimized lanthanide concentrations of 0.2 mol% and 6 mol%, respectively. Analogous experiments were performed on Eu-doped BaTiO3 and SrTiO3 motifs, but CaTiO3 still performed as the most effective host material amongst the three perovskite systems tested. Moreover, the ligand-capped CdSe QD-doped CaTiO3 heterostructures exhibited effective charge transfer between the two individual constituent nanoscale components, an assertion corroborated by the corresponding quenching of their measured PL signals.We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite

  3. Optical spectroscopy and band gap analysis of hybrid improper ferroelectric Ca{sub 3}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Cherian, Judy G.; Harms, Nathan C. [Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996 (United States); Birol, Turan; Vanderbilt, David [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Gao, Bin; Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Rutgers Center for Emergent Materials, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 (United States); Musfeldt, Janice L., E-mail: musfeldt@utk.edu [Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996 (United States); Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 (United States)

    2016-06-27

    We bring together optical absorption spectroscopy, photoconductivity, and first principles calculations to reveal the electronic structure of the room temperature ferroelectric Ca{sub 3}Ti{sub 2}O{sub 7}. The 3.94 eV direct gap in Ca{sub 3}Ti{sub 2}O{sub 7} is charge transfer in nature and noticeably higher than that in CaTiO{sub 3} (3.4 eV), a finding that we attribute to dimensional confinement in the n = 2 member of the Ruddlesden-Popper series. While Sr substitution introduces disorder and broadens the gap edge slightly, oxygen deficiency reduces the gap to 3.7 eV and gives rise to a broad tail that persists to much lower energies.

  4. Platinum-assisted phase transition in bismuth-based layer-structured ferroelectric CaBi4Ti4O15 thin films

    Science.gov (United States)

    Kato, Kazumi; Suzuki, Kazuyuki; Fu, Desheng; Nishizawa, Kaori; Miki, Takeshi

    2002-10-01

    The phase transition of nonferroelectric pyrochlore to ferroelectric perovskite in CaBi4Ti4O15 thin films depends on platinum bottom electrodes. Rather than the strain and crystallinity of the bottom electrode, matching of the atomic arrangement to the Ca-Bi-Ti-O thin films is predominant. CaBi4Ti4O15 thin films crystallized on (200)-oriented platinum at 650 degC showed c-axis orientation. In contrast, thin films crystallized on highly crystalline (111)-oriented platinum at the same temperature contained pyrochlore grains which were about several tens of nanometers in diameter and located in the interface region. They showed P-V hysteresis loops. The remanent polarization and coercive electric field depended on platinum top electrode size.

  5. A-site deficient perovskite-type compounds in the ternary CaTiO{sub 3}-LaCrO{sub 3}-La{sub 2/3}TiO{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Vashook, V. [Institute of Physical Chemistry and Electrochemistry, Dresden University of Technology, D-01062 Dresden (Germany)]. E-mail: vladimir.vashook@chemie.tu-dresden.de; Vasylechko, L. [Lviv Polytechnic National University, 12 Bandera St., Lviv 79013 (Ukraine); Trofimenko, N. [Fraunhofer Institute for Ceramic Technologies and Sintered Materials, D-01277 Dresden (Germany); Kuznecov, M. [Fraunhofer Institute for Ceramic Technologies and Sintered Materials, D-01277 Dresden (Germany); Otchik, P. [Fraunhofer Institute for Ceramic Technologies and Sintered Materials, D-01277 Dresden (Germany); Zosel, J. [Kurt-Schwabe-Institute for Measuring and Sensor Technology Meinsberg, D-04720 Ziegra-Knobelsdorf (Germany); Guth, U. [Institute of Physical Chemistry and Electrochemistry, Dresden University of Technology, D-01062 Dresden (Germany); Kurt-Schwabe-Institute for Measuring and Sensor Technology Meinsberg, D-04720 Ziegra-Knobelsdorf (Germany)

    2006-08-10

    Phase equilibriums in the CaTiO{sub 3}-LaCrO{sub 3}-La{sub 2/3}TiO{sub 3} quasi-ternary system have been studied by means of high-resolution powder diffraction technique using X-ray and synchrotron radiation. Over 50 La{sub (2+y-2x)/3}Ca {sub x}Cr {sub y}Ti{sub 1-y}O{sub 3} compounds were synthesized by solid-state reactions in air at 1350 deg. C using La{sub 2}O{sub 3}, CaCO{sub 3}, Cr{sub 2}O{sub 3} and TiO{sub 2}. Based on the results of X-ray phase and structural analysis, the isothermal section of the CaTiO{sub 3}-LaCrO{sub 3}-La{sub 2/3}TiO{sub 3} phase diagram at room temperature is constructed. The A-cation deficient La{sub (2+y-2x)/3}Ca{sub x}Cr {sub y}Ti{sub 1-y}O{sub 3} solid solution with different perovskite-type structures (space groups Pbnm, Imma, I4/mcm and Cmmm or P2/m) is formed in the CaTiO{sub 3}-LaCrO{sub 3}-La{sub 2/3}TiO{sub 3} quasi-ternary system in air conditions. The compounds show high stability at high temperatures at reducing as well as at oxidizing conditions. The substances with y = 0 and y = 0.2 show n-type conductivity at 900 deg. C at pO{sub 2} = 10{sup -15} to 10{sup 5} Pa and with y = 0.5 show conductivity minima these shift to the oxygen reach region with increasing A-site deficiency. The A-site deficient La{sub (2+y-2x)/3}Ca {sub x}Cr {sub y}Ti{sub 1-y}O{sub 3} samples have higher sintering ability in comparison with the cation stoichiometric La{sub 1-x}Ca {sub x}Cr{sub 1-y}Ti {sub y}O{sub 3} compositions and, in contrast to the latter, can be prepared as gas dense ceramics in air at temperatures lower as 1300 deg. C. Thermal expansion of the A-site deficient La{sub (2+y-2x)/3}Ca {sub x}Cr {sub y}Ti{sub 1-y}O{sub 3} ceramics is comparable with that of yttrium stabilised zirconia (YSZ). No interaction between La{sub (2+y-2x)/3}Ca {sub x}Cr {sub y}Ti{sub 1-y}O{sub 3} and YSZ ceramics up to 1300 deg. C was observed. Oxygen mobility in these ceramics can be characterised with chemical diffusion coefficients (1-9) x 10{sup -9} cm

  6. Preparation and optical characterization of Eu{sup 3+}-doped CaTiO{sub 3} perovskite powders

    Energy Technology Data Exchange (ETDEWEB)

    Huong, Duong Thi Mai; Nam, Nguyen Hoang; Vu, Le Van [Faculty of Physics, Hanoi University of Science, 334 Nguyen Trai Road, Thanh Xuan District, Hanoi (Viet Nam); Long, Nguyen Ngoc, E-mail: longnn@vnu.edu.vn [Faculty of Physics, Hanoi University of Science, 334 Nguyen Trai Road, Thanh Xuan District, Hanoi (Viet Nam)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer Seven vibration modes related to Eu{sup 3+} existed in high-energy region of Raman spectra. Black-Right-Pointing-Pointer Band edge of CaTiO{sub 3}:Eu{sup 3+} shifted to the higher-energy with increasing Eu{sup 3+}content. Black-Right-Pointing-Pointer Four weak absorption peaks related to the optical transitions in Eu{sup 3+} was observed. Black-Right-Pointing-Pointer Emission transitions from the {sup 5}D{sub J} states to the {sup 7}F{sub J} states were observed. - Abstract: CaTiO{sub 3} perovskite powders doped with 1.0, 1.5, 2.0, 2.5, 3.0, and 5.0 mol% Eu{sup 3+} were prepared by sol-gel technique followed by annealing at high temperatures. The powders were characterized by X-ray diffraction, scanning electron microscopy, Raman scattering, absorption, and photoluminescence spectroscopy. The obtained powders possessed orthorhombic crystal structure. Raman spectra of the CaTiO{sub 3}:Eu{sup 3+} powders exhibited seven new peaks at 798, 1048, 1188, 1371, 1441, 1601, and 1644 cm{sup -1} which were assigned to the localized vibrational modes related to the complexes containing Eu{sup 3+}. It was found that the band edge of the material shifted to the higher-energy side with increasing Eu{sup 3+}-impurity content. The photoluminescence of Eu{sup 3+} ions results from the radiative intra-configurational f-f transitions that happen between the {sup 5}D{sub J} (J = 0, 1-3) exited states and the {sup 7}F{sub J} (J = 0,1-4) ground states; the photoluminescence excitation of Eu{sup 3+} ions takes place from the {sup 7}F{sub 0} ground state to the {sup 5}D{sub J} (J = 1-4), {sup 5}L{sub 6}, and {sup 5}G{sub 2,6} exited states.

  7. Application of CaCO3, CaF2, SiO2, and TiO2 particles to silicone lens for enhancing angular color uniformity of white LED lamp

    Science.gov (United States)

    Nguyen, Anh Q. D.; Nguyen, Vinh H.

    2017-08-01

    In this study, we present an insightful investigation on optimal selection of scattering enhancement particles (SEP) to satisfy each specific optical property of white LEDs (WLEDs). The interested contenders include CaCO3, CaF2, SiO2, and TiO2, each of them is added with YAG:Ce phosphor compounding. The quality improvement on each considered property is demonstrated convincingly by applying Mie-scattering theory together with Monte Carlo simulation on a particular WLEDs which has the color temperature of 8500K. It is observed by simulation results that TiO2 particles provide the highest color uniformity among the SEP, as increasing TiO2 concentration. These results of this work can serve as a practical guideline for manufacturing high-quality WLEDs.

  8. Radiolabeling of DOTATOC with the long-lived positron emitter {sup 44}Sc

    Energy Technology Data Exchange (ETDEWEB)

    Pruszynski, Marek; Majkowska-Pilip, Agnieszka [Centre of Radiochemistry and Nuclear Chemistry, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warszawa (Poland); Loktionova, Natalia S.; Eppard, Elisabeth [Institute of Nuclear Chemistry, Johannes Gutenberg-University of Mainz, Fritz-Strassmann-Weg 2, D-55128 Mainz (Germany); Roesch, Frank, E-mail: frank.roesch@uni-mainz.de [Institute of Nuclear Chemistry, Johannes Gutenberg-University of Mainz, Fritz-Strassmann-Weg 2, D-55128 Mainz (Germany)

    2012-06-15

    The positron-emitting radionuclide {sup 44}Sc with a half-life of 3.97 h and a {beta}{sup +} branching of 94.3% is of potential interest for clinical PET. As so far it is available from a {sup 44}Ti/{sup 44}Sc generator in Mainz, where long-lived {sup 44}Ti decays to no-carrier-added (nca) {sup 44}Sc. The {sup 44}Sc is a trivalent metal cation and should be suitable for complexation with many well established bifunctional chelators conjugated to peptides or other molecular targeting vectors. Thus, the aim of this work was to investigate the potential of {sup 44}Sc for labeling of DOTA-conjugated peptides. DOTA-D-Phe{sup 1}-Tyr{sup 3}-octreotide (DOTATOC) was used as a model molecule to study and optimize labeling procedure. Reaction parameters such as buffer conditions, concentration of peptide, pH range, reaction temperature and time were optimized. Addition of 21 nmol of DOTATOC to {sup 44}Sc in ammonium acetate buffer pH 4.0 provided labeling yields >98% within 25 min of heating in an oil-bath at 95 Degree-Sign C. This time can be reduced to 3 min only by applying microwave supported heating. {sup 44}Sc-DOTATOC was found to be stable in 0.9% NaCl, PBS pH 7.4, fetal calf and human serums, and also in the presence of competing metal cations (Fe{sup 3+}, Ca{sup 2+}, Cu{sup 2+}, Mg{sup 2+}), as well as other ligand competitors, like EDTA and DTPA, even after almost 25 h incubation at 37 Degree-Sign C. Present study shows that nca {sup 44}Sc forms stable complexes with the macrocyclic ligand DOTA and that {sup 44}Sc-DOTATOC and analog targeting vectors may be synthesized for further preclinical and clinical investigations. - Highlights: Black-Right-Pointing-Pointer Labeling of somatostatin analouges with positron emitter {sup 44}Sc was tested. Black-Right-Pointing-Pointer DOTATOC was labeled with {sup 44}Sc isotope. Black-Right-Pointing-Pointer Optimal conditions for {sup 44}Sc-DOTATOC synthesis were found. Black-Right-Pointing-Pointer Stability of {sup 44}Sc

  9. Electromagnetic behavior of radar absorbing materials based on Ca hexaferrite modified with Co-Ti ions and doped with La

    Directory of Open Access Journals (Sweden)

    Valdirene Aparecida da Silva

    2009-06-01

    Full Text Available Radar Absorbing Materials (RAM are compounds that absorb incidental electromagnetic radiation in tuned frequencies and dissipate it as heat. Its preparation involves the adequate processing of polymeric matrices filled with compounds that act as radar absorbing centers in the microwave range. This work shows the electromagnetic evaluation of RAM based on CoTi and La doped Ca hexaferrite. Vibrating Sample Magnetization analyses show that ion substitution promoted low values for the parameters of saturation magnetization (123.65 Am2/kg and coercive field (0.07 T indicating ferrite softening. RAM samples obtained using different hexaferrite concentrations (40-80 per cent, w/w show variations in complex permeability and permittivity parameters and also in the performance of incidental radiation attenuation. Microwave attenuation values between 40 and 98 per cent were obtained.

  10. Ferro- and piezoelectric properties of polar-axis-oriented CaBi4Ti4O15 films

    Science.gov (United States)

    Kato, Kazumi; Fu, Desheng; Suzuki, Kazuyuki; Tanaka, Kiyotaka; Nishizawa, Kaori; Miki, Takeshi

    2004-05-01

    Polar-axis-oriented CaBi4Ti4O15 (CBTi144) films were fabricated on Pt foils using a complex metal alkoxide solution. The 500-nm-thick film showed the columnar structure and consisted of well-developed grains. The a/b-axis orientation of the ferroelectric films is considered to be associated with the preferred orientation of Pt foil. The film showed good ferro- and piezoelectric properties. The Pr and Ec were 25 μC/cm2 and 306 kV/cm, respectively, at an applied voltage of 115 V. The d33 was characterized as 30 pm/V by piezoresponse force microscopy. The values were twice as large as those of the CBTi144 thin film with random orientation. The polar-axis-oriented CBTi144 films would open up possibilities for devices as Pb-free piezoelectric materials.

  11. Bottom-up fabrication and piezoelectric properties of CaBi4Ti4O15 micro-plateaus

    Science.gov (United States)

    Kato, K.; Tanaka, K.; Kayukawa, S.; Suzuki, K.; Masuda, Y.; Kimura, T.; Nishizawa, K.; Miki, T.

    2007-08-01

    CaBi4Ti4O15 (CBTi144) micro-plateaus were fabricated on Si wafers and Pt foils using a self-assembled monolayer (SAM) and a complex metal alkoxide solution. The micro-plateaus are delineated by metal masks, which are used for shadowing against the ultraviolet (UV) irradiation for decomposition of SAM to make the surface hydrophilic. The micro-plateaus crystallized to a ferroelectric phase with random orientation. The crystallization depended on the SAM-derived ultra thin layers at the surface of the substrates. The primitive PFM measurements without any top electrodes confirmed that the micro-plateaus exhibited the piezoresponse behaviors. The piezoelectric constant, d33, had some distribution, and the maximum d33 was confirmed as about 45 pm/V, which is identical to the d33 of the polar-axis oriented CBTi144 thin films.

  12. Contrasting conduction mechanisms of two internal barrier layer capacitors: (Mn, Nb)-doped SrTiO3 and CaCu3Ti4O12

    Science.gov (United States)

    Tsuji, Kosuke; Chen, Wei-Ting; Guo, Hanzheng; Lee, Wen-Hsi; Guillemet-Fritsch, Sophie; Randall, Clive A.

    2017-02-01

    The d.c. conduction is investigated in the two different types of internal barrier layer capacitors, namely, (Mn, Nb)-doped SrTiO3 (STO) and CaCu3Ti4O12 (CCTO). Scanning electron microscopy (SEM) and Capacitance - Voltage (C-V) analysis are performed to estimate the effective electric field at a grain boundary, EGB. Then, the d.c. conduction mechanism is discussed based on the J (Current density)-EGB characteristics. Three different conduction mechanisms are successively observed with the increase of EGB in both systems. In (Mn, Nb)-doped STO, non-linear J-EGB characteristics is temperature dependent at the intermediate EGB and becomes relatively insensitive to the temperature at the higher EGB. The J- EGB at each regime is explained by the Schottky emission (SE) followed by Fowler-Nordheim (F-N) tunneling. Based on the F-N tunneling, the breakdown voltage is then scaled by the function of the depletion layer thickness and Schottky barrier height at the average grain boundary. The proposed function shows a clear linear relationship with the breakdown. On the other hand, F-N tunneling was not observed in CCTO in our measurement. Ohmic, Poole-Frenkel (P-F), and SE are successively observed in CCTO. The transition point from P-F and SE depends on EGB and temperature. A charge-based deep level transient spectroscopy study reveals that 3 types of trap states exist in CCTO. The trap one with Et ˜ 0.65 eV below the conduction band is found to be responsible for the P-F conduction.

  13. Microstructure and wear behavior of γ/Al 4C 3/TiC/CaF 2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

    Science.gov (United States)

    Liu, Xiu-Bo; Shi, Shi-Hong; Guo, Jian; Fu, Ge-Yan; Wang, Ming-Di

    2009-03-01

    As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3C 2-CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi ( γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi ( γ) matrix during the laser cladding process.

  14. Thermally stable dielectric responses in uniaxially (001)-oriented CaBi4Ti4O15 nanofilms grown on a Ca2Nb3O10- nanosheet seed layer

    Science.gov (United States)

    Kimura, Junichi; Takuwa, Itaru; Matsushima, Masaaki; Shimizu, Takao; Uchida, Hiroshi; Kiguchi, Takanori; Shiraishi, Takahisa; Konno, Toyohiko J.; Shibata, Tatsuo; Osada, Minoru; Sasaki, Takayoshi; Funakubo, Hiroshi

    2016-02-01

    To realize a high-temperature capacitor, uniaxially (001)-oriented CaBi4Ti4O15 films with various film thicknesses were prepared on (100)cSrRuO3/Ca2Nb3O10- nanosheet/glass substrates. As the film thickness decreases to 50 nm, the out-of-plane lattice parameters decrease while the in-plane lattice ones increase due to the in-plane tensile strain. However, the relative dielectric constant (ɛr) at room temperature exhibits a negligible degradation as the film thickness decreases to 50 nm, suggesting that ɛr of (001)-oriented CaBi4Ti4O15 is less sensitive to the residual strain. The capacitance density increases monotonously with decreasing film thickness, reaching a value of 4.5 μF/cm2 for a 50-nm-thick nanofilm, and is stable against temperature changes from room temperature to 400 °C irrespective of film thickness. This behaviour differs from that of the widely investigated perovskite-structured dielectrics. These results show that (001)-oriented CaBi4Ti4O15 films derived using Ca2Nb3O10- nanosheets as seed layers can be made candidates for high-temperature capacitor applications by a small change in the dielectric properties against film thickness and temperature variations.

  15. Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics.

    Science.gov (United States)

    Jung, Choong-Hwan; Kim, Yeon-Ku; Han, Young-Min; Lee, Sang-Jin

    2016-02-01

    A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

  16. X-ray photoemission spectroscopy investigation of CaTiO{sub 3}:Eu for luminescence property: effect of Eu{sup 3+} ion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kaichen [Third Hospital of Jilin University, Changchun 130031 (China); Zhao, Baijun [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Gao, Lu, E-mail: gaolu@jlu.edu.cn [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun (China)

    2016-06-15

    Graphical abstract: The influence on the photoluminescent performance due to the electronic structure change in Eu-doped CaTiO{sub 3} of the specific core-level and valence band spectrum via X-ray photoemission spectroscopy were characterized. - Highlights: • Single phase CaTiO{sub 3} and CaTiO{sub 3}: Eu crystals were prepared under mild hydrothermal method. • Crystal structure, doping level and the relations to their luminescent property were discussed. • Charge compensation mechanism was discussed via valance band spectrum by XPS. - Abstract: Charge compensation of on-site Eu 4f–5d transition that determines the luminescent performance was confirmed with valance band spectrum. Influence of photoelectrons from CaTiO{sub 3}: Eu to the corresponding luminescent performance was discussed based on the crystal structure, doping level and the relations to their luminescent property. This paper is important to further optimize the luminescent performance for improving the efficiency and reducing the cost in light emitting diode industry.

  17. Effect of structural transition on magnetic and optical properties of Ca and Ti co-substituted BiFeO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pawan; Kar, Manoranjan, E-mail: mano@iitp.ac.in

    2014-01-25

    Highlights: • Secondary phase formation has been controlled for Bi{sub 0.9}Ca{sub 0.1}Fe{sub 0.9}Ti{sub 0.1}O{sub 3} • Co-substitution of Ca and Ti at Bi and Fe sites significantly increases M{sub S} and H{sub C} • Compositional driven structural transition from rhombohedral to orthorhombic symmetry. • The leakage current has reduced significantly for Ca{sup 2+} and Ti{sup 4+} co-substituted BiFeO{sub 3}. • Small band gap of co-substituted BiFeO{sub 3} may be useful for optoelectronic devices. -- Abstract: Bi{sub 1−x}Ca{sub x}Fe{sub 1−x}Ti{sub x}O{sub 3} ceramics with x = 0.0, 0.05, 0.075, 0.10, 0.125, 0.15 and 0.2 nanoparticles were prepared by the tartaric acid modified sol–gel technique. The co-substitution of Ca and Ti in certain proportion controls the formation of secondary phases. Structural phase analysis by XRD suggested that pure bismuth ferrite stabilized in rhombohedral crystal symmetry (space group R3c) and orthorhombic (Pbnm) phase fraction was observed in co-substituted samples which increase with the increase in substitution percentage. The changes in the phonon frequencies (A{sub 1}) and line widths in Raman spectra reveal the lattice distortion in co-substituted samples which are in agreement with our XRD analysis. The improved magnetization and coercive field in co-substituted samples occurs due to the suppression of cycloid spin structure which could be explained in terms of field induced spin reorientation and weak ferromagnetism. The Ti{sup 4+} substitution at Fe site in BiFeO{sub 3} significantly reduced the oxygen vacancies and hence the associated leakage current, which leads to the increase of dielectric constant as well as frequency independent region for ∊{sub r} and tan δ (maximum in Bi{sub 0.85}Ca{sub 0.15}Fe{sub 0.85}Ti{sub 0.15}O{sub 3}). The significant decrease in dielectric loss with the increase in substitution percentage leads to the decrease in the room temperature bulk conductivity and thus enhanced

  18. Shape Memory Characteristics of Ti(sub 49.5)Ni(sub 25)Pd(sub 25)Sc(sub 0.5) High-Temperature Shape Memory Alloy After Severe Plastic Deformation

    Science.gov (United States)

    Atli, K. C.; Karaman, I.; Noebe, R. D.; Garg, A.; Chumlyakov, Y. I.; Kireeva, I. V.

    2011-01-01

    A Ti(49.5)Ni25Pd25Sc(0.5) high-temperature shape memory alloy is thermomechanically processed to obtain enhanced shape-memory characteristics: in particular, dimensional stability upon repeated thermal cycles under constant loads. This is accomplished using severe plastic deformation via equal channel angular extrusion (ECAE) and post-processing annealing heat treatments. The results of the thermomechanical experiments reveal that the processed materials display enhanced shape memory response, exhibiting higher recoverable transformation and reduced irrecoverable strain levels upon thermal cycling compared with the unprocessed material. This improvement is attributed to the increased strength and resistance of the material against defect generation upon phase transformation as a result of the microstructural refinement due to the ECAE process, as supported by the electron microscopy observations.

  19. DFT investigation of NH{sub 3}, PH{sub 3}, and AsH{sub 3} adsorptions on Sc-, Ti-, V-, and Cr-doped single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Buasaeng, Prayut; Rakrai, Wandee [Computational Chemistry Center for Nanotechnology and Department of Chemistry, Faculty of Science and Technology, Rajabhat Maha Sarakham University, Maha Sarakham, 44000 (Thailand); Wanno, Banchob [Center of Excellence for Innovation in Chemistry and Supramolecular Chemistry Research Unit, Department of Chemistry, Faculty of Science, Mahasarakham University, Maha Sarakham, 44150 (Thailand); Tabtimsai, Chanukorn, E-mail: tabtimsai.c@gmail.com [Computational Chemistry Center for Nanotechnology and Department of Chemistry, Faculty of Science and Technology, Rajabhat Maha Sarakham University, Maha Sarakham, 44000 (Thailand)

    2017-04-01

    Highlights: • Transition metal-doped single wall carbon nanotubes and their adsorption with NH{sub 3}, PH{sub 3} and AsH{sub 3} molecules were investigated using a DFT method. • Adsorptions of NH{sub 3}, PH{sub 3} and AsH{sub 3} molecules on pristine single wall carbon nanotubeswere improved by transition metal doping. • Structural and electronic properties of single wall carbon nanotubes were significantly changed by transition metal doping and gas adsorptions. - Abstract: The adsorption properties of ammonia (NH{sub 3}), phosphine (PH{sub 3}), and arsine (AsH{sub 3}) on pristine and transition metal- (TM = Sc, Ti, V, and Cr) doped (5,5) armchair single-walled carbon nanotubes (SWCNTs) were theoretically investigated. The geometric and electronic properties and adsorption abilities for the most stable configuration of NH{sub 3}, PH{sub 3}, and AsH{sub 3} adsorptions on pristine and TM-doped SWCNTs were calculated. It was found that the binding abilities of TMs to the SWCNT were in the order: Cr > V > Sc > Ti. However, the adsorption energy showed that the pristine SWCNT weakly adsorbed gas molecules and its electronic properties were also insensitive to gas molecules. By replacing a C atom with TM atoms, all doping can significantly enhance the adsorption energy of gas/SWCNT complexes and their adsorption ability was in the same order: NH{sub 3} > PH{sub 3} > AsH{sub 3}. A remarkable increase in adsorption energy and charge transfer of these systems was expected to induce significant changes in the electrical conductivity of the TM-doped SWCNTs. This work revealed that the sensitivity of SWCNT-based chemical gas adsorptions and sensors can be greatly improved by introducing an appropriate TM dopant. Accordingly, TM-doped SWCNTs are more suitable for gas molecule adsorptions and detections than the pristine SWCNT.

  20. Amorphization in Gd sub 2 Ti sub 2 O sub 7 and CaZrTi sub 2 O sub 7 irradiated with 3 meV argon ions

    Energy Technology Data Exchange (ETDEWEB)

    Weber, W.J.; Hess, N.J.; Maupin, G.D.

    1991-06-01

    Irradiation of Gd{sub 2}Ti{sub 2}O{sub 7} and CaZrTi{sub 2}O{sub 7} with 3 MeV Ar{sup +} ions results in the simultaneous expansion of the unit-cell volume and radiation-induced amorphization. The damage cross-sections for amorphization, which were determined by X-ray diffraction, are 0.023 nm{sup 2} and 0.014 nm{sup 2}, respectively. The damage cross-sections are relatively low and suggest some inherent resistance of these structures to amorphization, in agreement with previous studies. Transmission electron microscopy and electron diffraction confirmed the amorphous character of both materials at high fluences. Raman spectroscopy indicated a decrease in scattered intensity with ion fluence for the Raman-active vibrational modes of Gd{sub 2}Ti{sub 2}O{sub 7} and CaZrTi{sub 2}O{sub 7}. In the case of Gd{sub 2}Ti{sub 2}O{sub 7}, increases in both linewidth and wavenumber with ion fluence also were observed. 25 refs., 5 figs.

  1. Preparation of (001)-Oriented CaBi4Ti4O15 and SrBi4Ti4O15 Films Using LaNiO3 Nucleation Layer on Pt-passivated Si Wafer

    Science.gov (United States)

    Mizutani, Yuki; Uchida, Hiroshi; Funakubo, Hiroshi; Koda, Seiichiro

    2009-09-01

    Thin films of CaBi4Ti4O15 and SrBi4Ti4O15 with preferential crystal orientation were prepared by the chemical solution deposition (CSD) technique on a (100)LaNiO3/(111)Pt/(100)Si substrate. The films consisted of a crystalline phase of bismuth-layer-structured dielectric (BLSDs). The (00l) planes of a BLSD crystal were preferentially oriented to the surface of the (100)LaNiO3/(111)Pt/(100)Si substrate, which is ascribed to the lattice matching between pseudo perovskite blocks in the BLSD crystal and the (100)LaNiO3 plane with a perovskite structure. Frequent heat treatment for crystallization, i.e., once after each coating, also enhanced the degree of crystallinity and crystal orientation of the BLSD films. The dielectric constants (ɛr) of SrBi4Ti4O15 and CaBi4Ti4O15 thin films were approximately 250 at room temperature. The ɛr values of both films increased with ambient temperature. The variations in capacitance in the temperature range from 25 to 200 °C were approximately 3 and 5% respectively, which were significantly smaller than that in the (Ba,Sr)TiO3 thin film.

  2. Photoluminescence and ferroelectric properties of sol-gel-grown Eu-doped CaBi{sub 4}Ti{sub 4}O{sub 15} : Nd films

    Energy Technology Data Exchange (ETDEWEB)

    Wang Weichao; Zheng Haiwu; Liu Yuefeng; Li Zonghui; Zhang Ting; Zhang Weifeng [Key Laboratory of Photovoltaic Materials of Henan Province, Department of Physics, Institute of Physics for Microsystem, Henan University, Kaifeng 475004 (China)], E-mail: zhenghaiwu76@yahoo.com.cn, E-mail: wfzhang@henu.edu.cn

    2009-05-21

    Eu-doped CaBi{sub 4}Ti{sub 4}O{sub 15} : Nd (CBENT) ferroelectric thin films were prepared on Pt/Ti/SiO{sub 2}/Si substrates by a sol-gel method. The photoluminescence (PL) and ferroelectric properties of the films were investigated by using different annealing temperatures and concentrations of europium ions. All the CaBi{sub 3.75-x}Eu{sub x}Nd{sub 0.25}Ti{sub 4}O{sub 15} films have a polycrystalline bismuth-layered perovskite structure, and a morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases was shown to exist. The PL intensity of the CBENT films is significantly dependent on annealing temperature and Eu concentration. The remanent polarization 2Pr values of the Eu-doped CaBi{sub 4}Ti{sub 4}O{sub 15} : Nd thin films reaches a maximum value of 30.7 {mu}C cm{sup -2} when x is 0.2. The PL and ferroelectric properties suggest that CBENT films can be considered as promising multifunctional materials.

  3. Photoluminescence and ferroelectric properties of sol-gel-grown Eu-doped CaBi4Ti4O15 : Nd films

    Science.gov (United States)

    Wang, Weichao; Zheng, Haiwu; Liu, Yuefeng; Li, Zonghui; Zhang, Ting; Zhang, Weifeng

    2009-05-01

    Eu-doped CaBi4Ti4O15 : Nd (CBENT) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by a sol-gel method. The photoluminescence (PL) and ferroelectric properties of the films were investigated by using different annealing temperatures and concentrations of europium ions. All the CaBi3.75-xEuxNd0.25Ti4O15 films have a polycrystalline bismuth-layered perovskite structure, and a morphotropic phase boundary (MPB) between orthorhombic and tetragonal phases was shown to exist. The PL intensity of the CBENT films is significantly dependent on annealing temperature and Eu concentration. The remanent polarization 2Pr values of the Eu-doped CaBi4Ti4O15 : Nd thin films reaches a maximum value of 30.7 µC cm-2 when x is 0.2. The PL and ferroelectric properties suggest that CBENT films can be considered as promising multifunctional materials.

  4. Improved structure stability, optical and magnetic properties of Ca and Ti co-substituted BiFeO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay; Singh, Satyendra, E-mail: satyambd@gmail.com

    2016-11-15

    Graphical abstract: (a) UV–vis absorption spectra and (b) Tauc’s plots to determine the band gap of the Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} nanoparticles for x = 0 (S1), 0.05 (S2), 0.10 (S3), 0.15 (S4), 0.20 (S5) and 0.25 (S6), respectively (c) Variation of band gap with x for Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} nanoparticles. Display Omitted - Highlights: • First report on synthesis of Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3}, nanoparticles (0 ≤ x ≤ 0.25). • Ca and Ti co-substitutions control the formation of secondary phases and improved the stability of perovskite phase. • Strong absorption of visible light with a small optical band gap (1.77–2.26 eV). • Improved M{sub r} and H{sub c} due to the release of the latent magnetization locked within the toroidal spin structure. • May be useful for data storage, spintronics and optoelectronics. - Abstract: We report the optical and magnetic properties of single-crystalline Ca and Ti co-substituted bismuth ferrite, Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3}, nanoparticles, synthesized by a facile sol–gel methodology in the compositional range wherein 0 ≤ x ≤ 0.25. X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations show that all samples possess a rhombohedrally distorted perovskite structure with space group R3c. Ca and Ti co-substitution controls the formation of secondary phases and improved the stability of perovskite phase of BiFeO{sub 3}. The average particle size was estimated by Williamson Hall plot, confirmed by TEM, and found to be about 59, 50, 46, 41, 40 and 38 nm of Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} for x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25, respectively. The UV–vis absorption study reveal the strong absorption of visible light with a small optical band gap (1.77–2.25 eV) for 0 ≤ x ≤ 0.25 indicates a possibility of utilizing for photocatalytic activities. The magnetic study at room

  5. PbTiO3 modificado con Ca: de la cerámica a la lámina

    Directory of Open Access Journals (Sweden)

    Calzada, M. L.

    2004-06-01

    Full Text Available A review on calcium modified lead titanate, (Pb1-xCaxTiO3 bulk ceramics, through its structural and ferroelectric properties is described as well as the interest for the preparation of these materials as thin films. References to applications of these films, such as small electronic devices, are also reported. New experimental results on thin films with large Ca contents, fabricated by the sol-gel method, are reported. Results show that thin films have similar properties than bulk ceramics, but somewhat rather depressed. x-T phase diagram is discussed based on the current knowledge, on the relaxor phase appearance and on structural models. The singular dielectric properties of these thin films with x=0.5, are considered for applications in high density dynamic random access memories (DRAM and electronic components for high frequency (varactors.Se describe la evolución en el conocimiento sobre el titanato de plomo modificado con calcio, (Pb1-xCax TiO3, a través de sus propiedades estructurales y ferroeléctricas en forma cerámica hasta la actualidad y el interés por su conformación en láminas delgadas. Se hace referencia a su aplicabilidad en dispositivos electrónicos miniaturizados. Se aportan nuevos resultados experimentales en láminas delgadas de alto contenido en Ca, fabricadas mediante el método sol-gel. Los resultados obtenidos ponen de manifiesto cómo las propiedades medidas en cerámica se mantienen en lámina, aunque algo deprimidas. Se discute a la luz de los conocimientos actuales el diagrama de fases x-T, con especial atención a la aparición de la fase relaxora y a los modelos estructurales propuestos. Debido a las peculiares propiedades dieléctricas de las láminas de PTCa con x = 0.50, se discute la posibilidad de emplearlas en la fabricación de memorias dinámicas de acceso aleatorio (DRAM de alta densidad y en la preparación de componentes electrónicos para alta frecuencia (varactores.

  6. Magneto-thermopower in the Weak Ferromagnetic Oxide CaRu0.8Sc0.2O3: An Experimental Test for the Kelvin Formula in a Magnetic Material

    Science.gov (United States)

    Yamamoto, Takafumi D.; Taniguchi, Hiroki; Yasui, Yukio; Iguchi, Satoshi; Sasaki, Takahiko; Terasaki, Ichiro

    2017-10-01

    We have measured the resistivity, the thermopower, and the specific heat of the weak ferromagnetic oxide CaRu0.8Sc0.2O3 in external magnetic fields up to 140 kOe below 80 K. We have observed that the thermopower Q is significantly suppressed by magnetic fields at around the ferromagnetic transition temperature of 30 K, and have further found that the magneto-thermopower Δ Q(H,T) = Q(H,T) - Q(0,T) is roughly proportional to the magneto-entropy Δ S(H,T) = S(H,T) - S(0,T). We discuss this relationship between the two quantities in terms of the Kelvin formula, and find that the observed ΔQ is quantitatively consistent with the values expected from the Kelvin formula, a possible physical meaning of which is discussed.

  7. Comportamiento eléctrico del compuesto Bi5FeTi3O15 y de sus soluciones sólidas con CaBi4Ti4O15

    Directory of Open Access Journals (Sweden)

    Durán, P.

    1999-12-01

    Full Text Available Bi5FeTi3O15 (BiFT compound has been prepared by solid state reaction between the corresponding oxides. Its crystalline structure has been established by X ray Diffraction, (XRD. Ceramic samples with apparent density > 95% Dth have been sintered. On these samples, electrical conductivity and Curie temperature have been measured. Solid solutions of Bi5FeTi3O15 (BiFT and CaBi4Ti4O15 (CBiT have been prepared. On poled samples of these solid solutions, piezoelectric parameters have been established. The BiFT compound shows electrical conductivity values very similar to those of the Bi4Ti3O12 (BiT compound. The electrical conductivity of solid solutions is a function of CBiT amount. A possible electrical conductivity mechanism which is different of that accepted for the BiT compound is discussed.Se ha preparado Bi5FeTi3O15 (BiFT por reacción en estado sólido de los óxidos correspondientes. Se ha determinado su estructura cristalina por Difracción de Rayos X (DRX. Se han preparado compactos sinterizados con densidades superiores al 95%. Se ha determinado su temperatura de Curie, y la conductividad eléctrica entre 150 y 850ºC. Se han preparado soluciones sólidas de Bi5FeTi3O15 con CaBi4Ti4O15, (CBiT y se han determinado los mismos parámetros de temperatura de Curie y de conductividad para ellas. En las soluciones sólidas se han determinado los parámetros Piezoeléctricos de muestras polarizadas Debe destacarse que el compuesto Bi5FeTi3O15 presenta unos valores de conducción eléctrica más próximos a los correspondientes al Bi4Ti3O12 (BiT que a los de los compuestos MeBi4Ti4O15. La conductividad eléctrica de las soluciones sólidas varía con el contenido de CBiT. Se discute la posible existencia de un modelo de conducción eléctrica que difiere del aceptado hasta el momento para el BiT, basado en los defectos localizados en las capas Bi2O2 2-.

  8. Calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray and post-deposition thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ctibor, Pavel [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Kotlan, Jiri, E-mail: kotlan@ipp.cas.cz [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Pala, Zdenek [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Sedlacek, Josef [Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Hajkova, Zuzana; Grygar, Tomas Matys [Institute of Inorganic Chemistry ASCR, v.v.i., Husinec-Rez 1001, Rez (Czech Republic)

    2015-12-15

    Highlights: • Calcium titanate was sprayed by two different plasma spray systems. • Significant improvement of dielectric properties after annealing was observed. • Calcium titanate self-supporting parts can be fabricated by plasma spraying. - Abstract: This paper studies calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray technology. A water stabilized plasma gun (WSP) as well as a widely used gas stabilized plasma gun (GSP) were employed in this study to deposit three sample sets at different spray conditions. Prepared specimens were annealed in air at atmospheric pressure for 2 h at various temperatures from 530 to 1170 °C. X-ray diffraction (XRD), Raman spectroscopy and porosity measurements were used for sample characterization. Dielectric spectroscopy was applied to obtain relative permittivity, conductivity and loss factor frequency dependence. Band gap energy was estimated from reflectance measurements. The work is focused on the explanation of changes in microstructure and properties of a plasma sprayed deposit after thermal annealing. Obtained results show significant improvement of dielectric properties after thermal annealing.

  9. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2013-11-01

    Full Text Available This work reports the excellent dielectric properties of polyimide (PI embedded with CaCu3Ti4O12 (CCTO nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz–1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67 is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  10. Crystallographic and electronic structure of the Ca{sub 2}TiMnO{sub 6} double perovskite

    Energy Technology Data Exchange (ETDEWEB)

    López, J.P. Garzón [Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Grupo de Estudios de Materiales – GEMA, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Cardona, R. [Grupo de Estudios de Materiales – GEMA, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Santos, A. Sarmiento [Grupo de Superficies, Electroquímica y Corrosión, Universidad Pedagógica y Tecnológica de Colombia, Tunja (Colombia); Téllez, D.A. Landínez [Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Roa-Rojas, J., E-mail: jroar@unal.edu.co [Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia)

    2014-12-15

    In this work, we report synthesis and crystalline structure study of the Ca{sub 2}TiMnO{sub 6} complex perovskite, by X-ray diffraction experiments and through the application of the Rietveld refinement using the GSAS code. Results revealed the crystallization of the system in a tetragonal perovskite with the characteristic structure given by I4/m (#87) space group and lattice parameters a=5.339(4) Å and c=7.736(6) Å. Ab initio calculations of density of states (DOS) and electronic structure were carried out for this perovskite-like system, by the Density Functional Theory (DFT) and using the Full-potential Linearized Augmented Plane Waves (FP-LAPW) method. The exchange-correlation potential was treated using the Generalized Gradient Approximation (GGA). All calculations were carried-out using spin polarization. For the up spin orientation the compound has a semiconducting behavior and for down spin polarization it behaves like a conductor. The calculated effective magnetic moment in cell was 4.02 μ{sub B}, which is close to the expected value calculated from Hund's rules.

  11. Effect of orthorhombic distortion on dielectric and piezoelectric properties of CaBi4Ti4O15 ceramics

    Science.gov (United States)

    Tanwar, Amit; Sreenivas, K.; Gupta, Vinay

    2009-04-01

    High temperature bismuth layered piezoelectric and ferroelectric ceramics of CaBi4Ti4O15 (CBT) have been prepared using the solid state route. The formation of single phase material with orthorhombic structure was verified from x-ray diffraction and Raman spectroscopy. The orthorhombic distortion present in the CBT ceramic sintered at 1200 °C was found to be maximum. A sharp phase transition from ferroelectric to paraelectric was observed in the temperature dependent dielectric studies of all CBT ceramics. The Curie's temperature (Tc=790 °C) was found to be independent of measured frequency. The behavior of ac conductivity as a function of frequency (100 Hz-1 MHz) at low temperatures (<500 °C) follows the power law and is attributed to hopping conduction. The presence of large orthorhombic distortion in the CBT ceramic sintered at 1200 °C results in high dielectric constant, low dielectric loss, and high piezoelectric coefficient (d33). The observed results indicate the important role of orthorhombic distortion in determining the improved property of multicomponent ferroelectric material.

  12. Formation of Ca/P ceramic coatings by Plasma Electrolytic Oxidation (PEO) on Ti6Al4V ELI alloy

    Science.gov (United States)

    Rodriguez-Jaimes, Y.; Naranjo, D. I.; Blanco, S.; García-Vergara, S. J.

    2017-12-01

    The formation of PEO ceramic coatings on Ti6Al4V ELI alloy was investigated using a phosphate/calcium containing electrolyte at 300 and 400V at 310K for different times. The Plasma Electrolytic Oxidation (PEO) coated specimens were then heat treated at 873 and 1073K for 2 hours. Scanning electron microscopy, Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction analysis were used to study the composition and the morphology of the ceramic coatings. The corrosion behaviour of the coatings was studied by Electrochemical Impedance Spectroscopy (EIS) in Simulated Body Fluid (SBF). The PEO-treated specimens primarily revealed a porous structure with thickness between 4 and 12μm, according to the voltage and process time used. The coatings are mainly composed of hydroxyapatite; however, as the voltage and anodizing time increase, the Ca/P ratio decreases. Generally, the corrosion resistance of the alloy was improved by the PEO-treated coatings, although the specimens treated at 1073K showed the presence of cracks that reduced the protective effect of the coatings.

  13. Resistive switching behavior of BaTiO3/La0.8Ca0.2MnO3 heterostructures

    Science.gov (United States)

    Wang, S. Y.; Li, Meng; Liu, W. F.; Gao, J.

    2015-06-01

    The electric transport properties of BaTiO3/La0.8Ca0.2MnO3 heterostructures were investigated in the temperature range 100-320 K. It is found that the leakage current versus voltage (I-V) curves show strong temperature dependence, and at lower temperature (curves are diode-like asymmetric characteristics; while they exhibit resistive switching behavior at higher temperature. Moreover, the resistive switching coefficient increases with the elevated temperature. Such switching conduction has been ascribed to the modulation of interfacial barrier height in BaTiO3/La0.8Ca0.2MnO3 heterostructures upon the ferroelectric polarization flipping. Such type of resistive switching behavior based on a correlation between ferroelectric polarization and conductivity might become of particular interest for nonvolatile memory applications.

  14. Amorphization in Gd sub 2 Ti sub 2 O sub 7 and CaZrTi sub 2 O sub 7 irradiated with 3 MeV argon ions

    Energy Technology Data Exchange (ETDEWEB)

    Weber, W.J.; Hess, N.J.; Maupin, G.D. (Pacific Northwest Lab., Richland, WA (United States))

    1992-03-01

    Irradiation of Gd{sub 2}Tl{sub 2}O{sub 7} and CaZrTi{sub 2}O{sub 7} with 3 MeV Ar{sup +} ions results in the simultaneous expansion of the unit-cell volume and radiation-induced amorphization. The damage cross sections for amorphization, which were determined by X-ray diffraction, are 0.023 nm{sup 2} and 0.014 nm{sup 2}, respectively. These damage cross sections are relatively low and suggest some inherent resistance of these structures to amorphization, in agreement with previous studies. Transmission electron microscopy and electron diffraction confirmed the amorphous character of both materials at high fluences. Raman spectroscopy indicated a decrease in scattered intensity with ion fluence for the Raman-active vibrational modes of Gd{sub 2}Ti{sub 2}O{sub 7} and CaZrTi{sub 2}O{sub 7}. In the case of Gd{sub 2}Ti{sub 2}O{sub 7}, increases in both linewidth and wavenumber with ion fluence also were observed. (orig.).

  15. Fabrication of lead-free piezoelectric Li2CO3-added (Ba,Ca)(Ti,Sn)O3 ceramics under controlled low oxygen partial pressure and their properties

    Science.gov (United States)

    Noritake, Kouta; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

    2018-02-01

    Reduction-resistant lead-free (Ba,Ca)(Ti,Sn)O3 piezoceramics with high piezoelectric constants were fabricated by optimizing the amount of Li2CO3 added. Oxygen partial pressure was controlled during the sintering of (Ba,Ca)(Ti,Sn)O3 ceramics in a reducing atmosphere using H2–CO2 gas. Enhanced grain growth and a high-polarization state after poling treatment were achieved by adding Li2CO3. Optimizing the amount of Li2CO3 added to (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics sintered under a low oxygen partial pressure resulted in improved piezoelectric properties while maintaining the high sintered density. The prepared Li2CO3-added ceramic samples had homogeneous microstructures with a uniform dispersion of each major constituent element. However, the residual Li content in the 3 mol % Li2CO3-added (Ba0.95Ca0.05)(Ti0.95Sn0.05)O3 ceramics after sintering was less than 0.3 mol %. Sintered bodies of this ceramic prepared in a CO2 (1.5%)–H2 (0.3%)/Ar reducing atmosphere (PO2 = 10‑8 atm at 1350 °C), exhibited sufficient electrical resistivity and a piezoelectric constant (d 33) exceeding 500 pC/N. The piezoelectric properties of this nonreducible ceramic were comparable or superior to those of the same ceramic sintered in air.

  16. Defect correlated fluorescent quenching and electron phonon coupling in the spectral transition of Eu3+ in CaTiO3 for red emission in display application

    Science.gov (United States)

    Som, S.; Kunti, A. K.; Kumar, Vinod; Kumar, Vijay; Dutta, S.; Chowdhury, M.; Sharma, S. K.; Terblans, J. J.; Swart, H. C.

    2014-05-01

    This paper reports on the defect correlated self-quenching and spectroscopic investigation of calcium titanate (CaTiO3) phosphors. A series of CaTiO3 phosphors doped with trivalent europium (Eu3+) and codoped with potassium (K+) ions were prepared by the solid state reaction method. The X-ray diffraction results revealed that the obtained powder phosphors consisted out of a single-phase orthorhombic structure and it also indicated that the incorporation of the dopants/co-dopants did not affect the crystal structure. The scanning electron microscopy images revealed the irregular morphology of the prepared phosphors consisting out of μm sized diameter particles. The Eu3+ doped phosphors illuminated with ultraviolet light showed the characteristic red luminescence corresponding to the 5D0→7FJ transitions of Eu3+. As a charge compensator, K+ ions were incorporated into the CaTiO3:Eu3+ phosphors, which enhanced the photoluminescence (PL) intensities depending on the doping concentration of K+. The concentration quenching of Eu3+ in this host is discussed in the light of ion-ion interaction, electron phonon coupling, and defect to ion energy transfer. The spectral characteristics and the Eu-O ligand behaviour were determined using the Judd-Ofelt theory from the PL spectra instead of the absorption spectra. The CIE (International Commission on Illumination) parameters were calculated using spectral energy distribution functions and McCamy's empirical formula. Photometric characterization indicated the suitability of K+ compensated the CaTiO3:Eu3+ phosphor for pure red emission in light-emitting diode applications.

  17. Uniformly Porous Nanocrystalline CaMgFe1.33Ti3O12 Ceramic Derived Electro-Ceramic Nanocomposite for Impedance Type Humidity Sensor

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-11-01

    Full Text Available Since humidity sensors have been widely used in many sectors, a suitable humidity sensing material with improved sensitivity, faster response and recovery times, better stability and low hysteresis is necessary to be developed. Here, we fabricate a uniformly porous humidity sensor using Ca, Ti substituted Mg ferrites with chemical formula of CaMgFe1.33Ti3O12 as humidity sensing materials by solid-sate step-sintering technique. This synthesis technique is useful to control the grain size with increased porosity to enhance the hydrophilic characteristics of the CaMgFe1.33Ti3O12 nanoceramic based sintered electro-ceramic nanocomposites. The highest porosity, lowest density and excellent surface-hydrophilicity properties were obtained at 1050 °C sintered ceramic. The performance of this impedance type humidity sensor was evaluated by electrical characterizations using alternating current (AC in the 33%–95% relative humidity (RH range at 25 °C. Compared with existing conventional resistive humidity sensors, the present sintered electro-ceramic nanocomposite based humidity sensor showed faster response time (20 s and recovery time (40 s. This newly developed sensor showed extremely high sensitivity (%S and small hysteresis of <3.4%. Long-term stability of the sensor had been determined by testing for 30 consecutive days. Therefore, the high performance sensing behavior of the present electro-ceramic nanocomposites would be suitable for a potential use in advanced humidity sensors.

  18. H2 Production Under Visible Light Irradiation from Aqueous Methanol Solution on CaTiO3:Cu Prepared by Spray Pyrolysis

    Science.gov (United States)

    Lim, Sung Nam; Song, Shin Ae; Jeong, Yong-Cheol; Kang, Hyun Woo; Park, Seung Bin; Kim, Ki Young

    2017-10-01

    Perovskite-type photocatalysts of CaCu x Ti1- x O3 (0 ≤ x ≤ 0.02) powder were prepared by spray pyrolysis of aqueous solution or aqueous solution with polymeric additive. The effects of the amount of copper ions doped in the photocatalyst and the precursor type on the photocatalytic activity under visible-light irradiation were investigated. The crystal structure, oxidation state, and light adsorption properties of the prepared photocatalysts were analyzed using x-ray diffraction, x-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy, respectively. The doping of copper ions in CaTiO3 allowed visible-light absorption owing to a narrowing of the band gap energy of the host material through the formation of a new donor level for copper ions. Among the doped samples prepared from the aqueous precursor, CaTiO3 doped with 1 mol.% copper ions had the highest hydrogen evolution rate (140.7 μmol g-1 h-1). Notably, the hydrogen evolution rate of the photocatalyst doped with 1 mol.% copper ions prepared from the aqueous precursor with polymeric additive (295.0 μmol g-1 h-1) was two times greater than that prepared from the aqueous precursor, due to the morphology effect.

  19. Uniformly Porous Nanocrystalline CaMgFe1.33Ti3O12 Ceramic Derived Electro-Ceramic Nanocomposite for Impedance Type Humidity Sensor

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Shasmin, Hanie Nadia; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Since humidity sensors have been widely used in many sectors, a suitable humidity sensing material with improved sensitivity, faster response and recovery times, better stability and low hysteresis is necessary to be developed. Here, we fabricate a uniformly porous humidity sensor using Ca, Ti substituted Mg ferrites with chemical formula of CaMgFe1.33Ti3O12 as humidity sensing materials by solid-sate step-sintering technique. This synthesis technique is useful to control the grain size with increased porosity to enhance the hydrophilic characteristics of the CaMgFe1.33Ti3O12 nanoceramic based sintered electro-ceramic nanocomposites. The highest porosity, lowest density and excellent surface-hydrophilicity properties were obtained at 1050 °C sintered ceramic. The performance of this impedance type humidity sensor was evaluated by electrical characterizations using alternating current (AC) in the 33%–95% relative humidity (RH) range at 25 °C. Compared with existing conventional resistive humidity sensors, the present sintered electro-ceramic nanocomposite based humidity sensor showed faster response time (20 s) and recovery time (40 s). This newly developed sensor showed extremely high sensitivity (%S) and small hysteresis of sensor had been determined by testing for 30 consecutive days. Therefore, the high performance sensing behavior of the present electro-ceramic nanocomposites would be suitable for a potential use in advanced humidity sensors. PMID:27916913

  20. Precipitation and solidification of calzirtite in liquid phase sintered ZrO[sub 2] (10. 8 mol. %CaO) with TiO[sub 2] additions

    Energy Technology Data Exchange (ETDEWEB)

    Shen Pouyan; Hon Yungshon (Inst. of Materials Science and Engineering, National Sun Yat-Sen Univ., Kaohsiung (Taiwan))

    1992-12-30

    Microstructure of calzirtite (Ca[sub 2]Zr[sub 5]Ti[sub 2]O[sub 16]) in CaO-ZrO[sub 2]-TiO[sub 2] ceramics was studied by transmission electron microscopy. The ceramics were prepared by liquid phase sintering (1600degC, 6h) powders of calcia-partially stabilized zirconia (PSZ of composition ZrO[sub 2]-10.8mol.%CaO and phase assemblages of tetragonal (t) ZrO[sub 2] in the cubic (c) ZrO[sub 2] matrix) and adding to them 2 mol.%, 4 mol.% and 8 mol.% TiO[sub 2] (designated specimens 2T, 4T and 8T respectively). Calzirtite was not formed in specimen 2T, but formed in the grain-boundary liquid of specimens 4T and 8T by epitaxial nucleation from ZrO[sub 2] followed cellular of spherulitic growth to form plate-like variants with [l brace]200[r brace] habit plane which elongated predominantly along the crystallographic c axis. For specimens 8T, calzirtite was formed in the shell region of the PSZ grains and appeared more or less equiaxed by domain nucleation within the c-ZrO[sub 2] matrix. In addition to the effect of interfacial energy, structural similarity was crucial for nucleating calzirtite epitaxially from ZrO[sub 2]. (orig.).

  1. Detector de IR de lámina ferroeléctrica de (Pb,CaTiO3

    Directory of Open Access Journals (Sweden)

    González, A.

    2002-02-01

    Full Text Available A sol-gel (Pb0.76Ca0.24TiO3 solution was deposited onto Pt/MgO(100 substrates. Previous thermal treatment of the substrate and the high rate of crystallization heating promote an important preferred orientation along the polar axis, and therefore selfpolarization , very convenient for the use of IR pyroelectric detectors. By depositing circular electrodes, 7.10-3 cm2 of area, an array of small capacitors are developed which are characterized as detectors in standard conditions: radiation from a black-body at 500 K, modulated between 1-20 Hz, a lock-in amplifier and an electronic circuit to sense and treat the electrical response. Three main factors affecting the detector performances are analyzed: a Figures of merit of the pyroelectric material; b assembly of the whole parts of detector (substrate, electrodes, leads, frame, etc and c electronic circuitry to sense and amplify signals. Thermal isolation is concluding as the most important fact to improve responsivity.Se han obtenido depósitos multicapa de titanato de plomo modificado con calcio, (Pb0.76Ca0.24TiO3, mediante un método de sol-gel, sobre substratos de Pt/MgO(100. El tratamiento térmico del substrato y la cristalización de las multicapas mediante tasas de calentamiento rápidas causan el desarrollo de una importante orientación preferente según el eje polar, perpendicular al mismo, lo que supone una autopolarización muy rentable para su empleo en detectores piroeléctricos de radiación infrarroja. Mediante una configuración de electrodos discretos se fabrican minicondensadores de 7.10-3 cm2 de área con los que se caracteriza ópticamente el detector para condiciones estándar: cuerpo negro a 500 K, modulación mecánica de la radiación entre 1-20 Hz, una electrónica de acondicionamiento de la señal de respuesta y un amplificador sintonizado para medir la respuesta en voltaje. Se analiza el efecto de los tres factores que intervienen en la fabricación del detector: a

  2. Energy dependence of thermoluminescent response of CaSO{sub 4}:Dy, LiF:Mg and micro LiF:Mg,Ti in clinical beams of electrons by using different simulator objects; Dependencia energetica da resposta TL de dosimetros de CaSO{sub 4}:Dy, LiF:Mg e microLiF:Mg,Ti em feixes clinicos de eletrons utilizando diferentes objetos simuladores

    Energy Technology Data Exchange (ETDEWEB)

    Bravim, Amanda; Campos, Leticia Lucente, E-mail: abravin@ipen.b, E-mail: rsakuraba@einstein.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sakuraba, Roberto K.; Cruz, Jose Carlos da, E-mail: rsakuraba@einstein.b, E-mail: josecarlosc@einstein.b [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil)

    2011-10-26

    Yet not so widely applied in radiotherapy, the calcium sulfate doped with dysprosium (CaSO{sub 4}:Dy) is used in radioprotection and studies has been demonstrated its great potential for the dosimetry in radiotherapy. This work evaluates the energy dependence of the thermoluminescent answer of the CaSO{sub 4}:D, LiF:Mg,Ti (TLD-100) and micro LiF:Mg,Ti in clinical beams of electrons by using water simulators, PMMA and solid water

  3. Production Potential of 47Sc Using Spallation Neutron Flux at the Los Alamos Isotope Production Facility

    Science.gov (United States)

    2014-03-27

    bins will be listed [20]. This tally, in combination with the eighth entry on MCNPs LCA physics model card entry, NOACT, is very useful in extracting...19 and 23 (K, Ca, Sc, Ti, and V) resulting from direct neutron reactions. The 8th LCA entry of NOACT=-2 forces the model to assume all particles react...the LCA line. The LCA line is altered to indicate which physics model to use, and was modified for an investigation of Bertini, Isabel, INCL4 and

  4. Flexible tensile strain sensor based on lead-free 0.5Ba (Ti0.8Zr0.2) O3-0.5(Ba0.7Ca0.3) TiO3 piezoelectric nanofibers

    Science.gov (United States)

    Xing, Lindong; Zhu, Ruijian; Wang, Zengmei; Wang, Fengxia; Kimura, Hideo

    2017-09-01

    Here, we report our study results of a flexible piezoelectric tensile strain sensor which is fabricated by synthesizing 0.5Ba (Zr0.2Ti0.8) O3-0.5(Ba0.7Ca0.3) TiO3 (0.5BZT-0.5BCT) nanofibers via an electrospinning process. Our nanofibers show an ultrahigh d33 of 275 pm V-1. 0.5BZT-0.5BCT nanofibers and MW-CNTs are dispersed in polydimethylsiloxane (PDMS) to fabricate a highly stretchable and flexible tensile sensor, and the multiple roles of the MW-CNTs are probed and demonstrated. This nanofiber-based piezoelectric tensile strain sensor shows great resolution and sensitivity under external mechanical deformation. It is suitable for applications in complex environments.

  5. Control of retention and fatigue-free characteristics in CaBi 4Ti 4O 15 thin films prepared by chemical method

    Science.gov (United States)

    Simões, A. Z.; Ramírez, M. A.; Gonzalez, A. H. M.; Riccardi, C. S.; Ries, A.; Longo, E.; Varela, J. A.

    2006-07-01

    Ferroelectric CaBi 4Ti 4O 15 (CBTi144) thin films were deposited on Pt/Ti/SiO 2/Si substrates by the polymeric precursor method. The films present a single phase of layered-structured perovskite with polar axis orientation after annealing at 700 °C for 2 h in static air and oxygen atmosphere. The a/ b-axis orientation of the ferroelectric film is considered to be associated with the preferred orientation of the Pt bottom electrode. It is noted that the films annealed in static air showed good polarization fatigue characteristics at least up to 10 10 bipolar pulse cycles and excellent retention properties up to 10 4 s. On the other hand, oxygen atmosphere seems to be crucial in the decrease of both, fatigue and retention characteristics of the capacitors. Independently of the applied electric field, the retained switchable polarization approached a nearly steady-state value after a retention time of 10 s.

  6. Viabilidad de películas delgadas de (Pb, Ca TiO3 depositadas sobre Pt/TiO2/SiO2/Si(100 en aplicaciones de conmutación

    Directory of Open Access Journals (Sweden)

    Ramos, P.

    1999-10-01

    Full Text Available (Pb,CaTiO3 ferroelectric thin films have been spin-coated on Pt/TiO2/SiO2/Si(100 substrates from sol-gel synthesized solutions. Selecting the solution concentrations and the excess of PbO content, stoichiometric composicion with reduced strains are obtained. Crystallization process by rapid thermal treatment (RTP promote preferred orientations [001]/[100] resulting a thiner ferroelectric-platinum interface layer, which causes the improvement of fatigue and retain behaviour, despite the use of platinum electrodes. These experimental finds let to cosider the described methode of processing very convenient to prepare thin films of this composition to use on switching applications such as non volatil RAM memories.Se han depositado láminas delgadas de (Pb,CaTiO3 sobre substratos de Pt/TiO2/SiO2/Si(100 por centrifugación, partiendo de soluciones sintetizadas por sol-gel. La concentración de las soluciones y el contenido de PbO se seleccionaron para minimizar las tensiones de las láminas cristalizadas y obtener la adecuada estequiometria. La cristalización mediante un calentamiento rápido (RTP, conduce a láminas con orientaciones preferentes [001]/[001], reducida capa interfacial ferroeléctrico-Pt y composición deseada. Los parámetros ferroeléctricos obtenidos muestran una mejora de las propiedades. Estas láminas presentan una fatiga y envejecimiento mucho más moderados que otros materiales alternativos depositados sobre substratos iguales, lo que permite considerar al método descrito como muy valioso para conseguir materiales susceptibles de emplear en aplicaciones de conmutación.

  7. Detector de IR de lámina ferroeléctrica de (Pb,Ca)TiO3

    OpenAIRE

    González, A; Calzada, M L; Jiménez, R; Mendiola, J.; Ramos, P.; Tejedor, P.

    2002-01-01

    A sol-gel (Pb0.76Ca0.24)TiO3 solution was deposited onto Pt/MgO(100) substrates. Previous thermal treatment of the substrate and the high rate of crystallization heating promote an important preferred orientation along the polar axis, and therefore selfpolarization , very convenient for the use of IR pyroelectric detectors. By depositing circular electrodes, 7.10-3 cm2 of area, an array of small capacitors are developed which are characterized as detectors in standard conditions: radiation f...

  8. Thermal expansion analysis and structural characteristics of the (Pb, Ca)TiO{sub 3} solid solutions from 150 to 570 K; Analise da expansao termica volumetrica e das caracteristicas estruturais de solucoes solidas de (Pb, Ca)TiO{sub 3} entre 150 e 570 K

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, F.R.; Eiras, J.A.; Garcia, D., E-mail: frestrada@df.ufscar.br, E-mail: eiras@df.ufscar.br, E-mail: ducinei@df.ufscar.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Fisica. Grupo de Materiais Ferroicos

    2017-01-15

    Ceramic samples of lead modified calcium titanate (Pb{sub 1-x}Ca{sub x} TiO{sub 3}) with calcium concentration between 0.24≤x≤0.55 were prepared and analyzed in order to determine the structural origin of the negative thermal expansion observed in this ferroelectric system. The Rietveld structural refinement method was used to assess the thermal evolution of the structural parameters using powder X-ray diffraction data collected between 150 and 570 K. Since the Pb{sub 1-x}Ca{sub x} TiO{sub 3} phase diagram and space groups are still unknown for the temperature range investigated, the structural analyses were based on adjustments of the refinement protocol. The results revealed the existence of a correlation between symmetry transitions and anomalies in the thermal expansion of the unit cell, being such transitions not necessarily of the ferroelectric-paraelectric nature. (author)

  9. Effect of Sintering Time and Diameter on Bi-Pb-Sr-Ca-Cu-O Superconducting Wire Formation with TiO2 Dopant by Silver (Ag Tube

    Directory of Open Access Journals (Sweden)

    Cindy Al Kindi

    2018-01-01

    Full Text Available Pengaruh waktu sintering dan diameter terhadap pembentukan kawat superkonduktor Bi-Pb-Sr-Ca-Cu-O dengan dopan TiO2 menggunakan tabung perak (Ag menjadi penting untuk dibahas karena hal ini berpengaruh terhadap adanya suhu kritis yang merupakan syarat penting superkonduktor. Pada penelitian ini ada beberapa tahap yang dilakukan yaitu preparasi bahan, proses permesinan, penarikan kawat dan proses perlakuan panas. Serbuk BPSCCO dengan dopan TiO2 dimasukkan ke dalam tabung perak (Ag dan dikalsinasi pada temperatur 820oC selama 20 jam, lalu proses penarikan (Rolling sampai diameter 6 mm dan 2,6 mm serta sintering dilakukan pada temperatur 850oC selama 9 jam dan 30 jam untuk masing-masing ukuran diameter dengan dua kali proses sintering. Hasil penelitian menunjukkan bahwa kawat superkonduktor memiliki suhu kritis yaitu Tc onset = 99 K dan Tc zero = 70 K. Waktu yang sangat berpengaruh pada pembentukan fasa superkonduktor yaitu sintering selama 9 jam sedangkan untuk ukuran diameter kawat yang memiliki suhu kritis yaitu 6 mm, sedangkan waktu sintering selama 30 jam dapat merubah fasa BPSCCO sehingga tidak terbentuk superkonduktor melainkan konduktor dan semikonduktor. Pada diameter 2,6 mm belum menjadi ukuran yang tepat pada pembentukan kawat superkonduktor.   The influence of sintering time and diameter on the formation of Bi-Pb-Sr-Ca-Cu-O superconducting wire with doped TiO2 by silver (Ag tube becomes important to be discussed because of the presence of critical temperature which is an essential condition in superconductors. In this research there are several steps must be done that is: material preparation, machine process, wire drawing and heat process. BPSCCO powder with dopant TiO2 filled into silver (Ag tube with calcination temperature at 820oC for 20 h, then rolling process to diameter 6 mm and 2,6 mm with sintering temperature at 850oC for 9 h and 30 h for each size of diameter by twice sintering process. The results showed that

  10. Enhanced electrical and magnetic properties in La0.7Sr0.3MnO3 thin films deposited on CaTiO3-buffered silicon substrates

    Directory of Open Access Journals (Sweden)

    C. Adamo

    2015-06-01

    Full Text Available We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100 Si by reactive molecular-beam epitaxy (MBE for the epitaxial integration of the colossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic and electrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-buffered silicon (CaTiO3/Si are compared with those deposited on SrTiO3-buffered silicon (SrTiO3/Si. In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 buffer layer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin films on silicon substrates.

  11. Enhanced electrical and magnetic properties in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited on CaTiO{sub 3}-buffered silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, C. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Méchin, L.; Guillet, B.; Wu, S.; Routoure, J.-M. [Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, (GREYC-UMR 6072), CNRS-ENSICAEN—Université de Caen Basse-Normandie, 6 Boulevard Maréchal Juin, 14050 Caen Cedex (France); Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Katz, M.; Pan, X. Q. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Mercone, S. [Laboratoire de Sciences des Procédés et des Matériaux, UPR3407, CNRS, Institut Galilee, Universite Paris-Nord, Villetaneuse (France); Schubert, J.; Zander, W. [Peter Grünberg Institute (PGI9-IT), JARA-Fundamentals of Future Information Technology, Research Centre Jülich, Jülich D-52425 (Germany); Misra, R. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Schiffer, P. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); and others

    2015-06-01

    We investigate the suitability of an epitaxial CaTiO{sub 3} buffer layer deposited onto (100) Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of the colossal magnetoresistive material La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with silicon. The magnetic and electrical properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films deposited by MBE on CaTiO{sub 3}-buffered silicon (CaTiO{sub 3}/Si) are compared with those deposited on SrTiO{sub 3}-buffered silicon (SrTiO{sub 3}/Si). In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO{sub 3} buffer layer. These results are relevant to device applications of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on silicon substrates.

  12. Magnetic properties of (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} composites

    Energy Technology Data Exchange (ETDEWEB)

    Eremina, R. M., E-mail: REremina@yandex.ru; Sharipov, K. R.; Yatsyk, I. V.; Lyadov, N. M. [Zavoisky Physical-Technical Institute (Russian Federation); Gilmutdinov, I. F.; Kiiamov, A. G. [Kazan Federal University (Russian Federation); Kabirov, Yu. V.; Gavrilyachenko, V. G. [Southern Federal University (Russian Federation); Chupakhina, T. I. [Russian Academy of Sciences, Institute of Solid State Chemistry, Ural Branch (Russian Federation)

    2016-07-15

    New composite materials (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} (x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5–300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe{sub 12}O{sub 19}){sub 0.05}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 0.95} composite “magnetize” CaCu{sub 3}Ti{sub 4}O{sub 12} at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe{sub 12}O{sub 19} “core.” The magnetic resonance line below 200 K splits into two lines corresponding to SrFe{sub 12}O{sub 19} and CaCu{sub 3}Ti{sub 4}O{sub 12}. The core effect decoration is manifested in the increase in the Curie–Weiss temperature from 25 K in CaCu{sub 3}Ti{sub 4}O{sub 12} without the doping ceramics to 80 K in the composite with 5% of SrFe{sub 12}O{sub 19}.

  13. EFFECT OF TiO2 ADDITION ON BONDING STRENGTH OF CaO-P2O5 Na2O-TiO2 BIOACTIVE GLASS CERAMIC COATING

    Directory of Open Access Journals (Sweden)

    B Eftekhari Yekta

    2014-12-01

    Full Text Available The effect of titanium dioxide addition on bonding strength of CaO-P2O5 -Na 2O-TiO2glass-ceramic system was investigated as a coating on titanium substrate. Thus, different amounts of TiO2 (2, 3.5 and 5mol % were added to the base glass batch composition. The prepared glaze slips were applied on the substrate by dip coating method, dried and then heat treated at various temperatures. After that, bonding strength of the glass- substrates was determined via shear stress testing method. The de-bonded interfaces were analyzed by scanning electron microscopy (SEM. According to these results, the 5 mol% TiO 2 containing coating showed the best bonding strength, comparing with the other coatings. The bioactivity of the coated samples was investigated by soaking them in simulated body fluid (SBF. The surface of the samples was studied using SEM and X-Ray microprobe and it was observed that an apatite layer was grown on their surface

  14. Magnetic behavior of La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Ordonez, John E.; Gomez, Maria E.; Lopera, Wilson; Marin, Lorena; Pardo, Jose A.; Morellon, Luis; Algarabel, Pedro; Prieto, Pedro

    2013-03-01

    We have grown ferroelectric BaTiO3(BTO) and ferromagnetic La2/3Ca1/3MnO3 (LCMO) onto (001) SrTiO3 and Nb:SrTiO3 by pulsed laser deposition (PLD) at pure oxygen atmosphere, and a substrate temperature of 820° C, seeking for a multiferroic behavior in this structure. From x-ray diffraction (XRD) we found lattice parameter aBTO=4.068 Å, and aLCMO=3.804 Å, for each individual layer. In the BTO/LCMO bilayer, (002)-Bragg peak for BTO maintain its position whereas (002) LCMO peak shift to lower Bragg angle indicating a strained LCMO film. Magnetization measurements reveal an increase in the Curie temperature from 170 K to 220 K for the bilayer when LCMO (t = 47 nm) is deposited on BTO (t=52 nm) film, while depositing the BTO (50 nm) above LCMO (48 nm) the Curie temperature remains at values close to that obtained for a LCMO single layer (~175 K), deposited under identical growth parameters This work has been supported by Instituto de Nanociencias de Aragón, Zaragoza, Spain, ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' COLCIENCIAS-CENM Contract RC 275-2011 and Research Project COLCIENCIAS-UNIVALLE.

  15. Influence of CaCO3, Al2O3, and TiO2 microfillers on physico-mechanical properties of Luffa cylindrica/polyester composites

    Directory of Open Access Journals (Sweden)

    Vinay Kumar Patel

    2016-06-01

    Full Text Available The development of natural fibre reinforced polymer composites has gained popularity in many applications due to their environment friendly characteristics over the synthetic fibre based polymer composites. This paper describes the fabrication and physical, mechanical, three-body abrasive wear and water absorption behaviour of Luffa fibre reinforced polyester composites with and without addition of micro-fillers of Al2O3, CaCO3 and TiO2. The ranking of the composite materials has been made by using Technique for order preference by similarity to ideal solution (TOPSIS method with output parameters of their physical, mechanical and abrasive wear and water absorption attributes. The addition of microfillers has enhanced greatly the physical and mechanical properties of Luffa-fibre based composites. The addition of microfillers has influenced the physico-mechanical properties of Luffa-fibre based polyester composites in descending order of CaCO3, Al2O3, and TiO2.

  16. AC Electroluminescent Processes in Pr3+-Activated (Ba0.4Ca0.6TiO3 Diphase Polycrystals

    Directory of Open Access Journals (Sweden)

    Nan Gao

    2017-05-01

    Full Text Available We investigated the properties of alternating current (AC-driven electroluminescence from (Ba0.4Ca0.6TiO3:Pr3+ diphase polycrystal-based device. The results of crystal phases and micrographs, and the symmetrical dual emissions in one AC cycle, indicate the spontaneous formation of a dielectric/phosphor/dielectric sandwich microstructure in (Ba0.4Ca0.6TiO3:Pr3+. The electroluminescent device emits a red light of 617 nm, which is attributed to the 1D2-3H4 transition of Pr3+ in the phosphor phase. At a fixed AC frequency, the intensity of electroluminescence exhibits a steep enhancement when applying an increased driving electric field that is beyond a threshold. In a fixed driving electric field, the intensity of electroluminescence shows a rapid rise at low frequencies, but reaches saturation at high frequencies. Based on a double-injection model, we discussed systematically the electroluminescent processes in a whole cycle of AC electric field, which matched well with the experimental data. Our investigation is expected to expand our understanding of such a diphase electroluminescent device, thereby promoting their applications in lighting and displays.

  17. Fabrication and characterization of polyvinyl alcohol/metal (Ca, Mg, Ti) doped zirconium phosphate nanocomposite films for scaffold-guided tissue engineering application.

    Science.gov (United States)

    Kalita, Himani; Pal, Pallabi; Dhara, Santanu; Pathak, Amita

    2017-02-01

    Nanocomposite films of polyvinyl alcohol (PVA) and zirconium phosphate (ZrP)/doped ZrP (doped with Ca, Mg, Ti) nanoparticles have been developed by solvent casting method to assess their potential as matrix material in scaffold-guided tissue engineering application. The prepared ZrP and doped ZrP nanoparticles as well as the nanocomposite films were characterized by various spectroscopic and microscopic techniques. Nanoindentation studies revealed improved nanomechanical properties in the PVA/doped ZrP nanocomposite films (highest for PVA/Ti doped ZrP: hardness=262.4MPa; elastic modulus=5800MPa) as compared to the PVA/ZrP and neat PVA films. In-vitro cell culture experiments carried out to access the cellular viability, attachment, proliferation, and migration on the substrates, using mouse fibroblast (3T3) cell lines, inferred enhanced bioactivity in the PVA/doped ZrP nanocomposite films (highest for PVA/Ca doped ZrP) in contrast to PVA/ZrP and neat PVA films. Controlled biodegradability as well as swelling behavior, superior bioactivity and improved mechanical properties of the PVA/doped ZrP nanocomposite films make them promising matrix materials for scaffold-guided tissue engineering application. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

    Science.gov (United States)

    Liu, Donglin; Shim, Jaeshik; Sun, Yue; Li, Qiang; Yan, Qingfen

    2017-09-01

    Lead-free Ca, Zr co-doped BaTiO3 (BCZT) single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

  19. Structure, tribocorrosion and biocide characterization of Ca, P and I containing TiO{sub 2} coatings developed by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz de Viteri, V., E-mail: virginia.saenzdeviteri@tekniker.es [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Bayón, R.; Igartua, A. [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Barandika, G. [Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, Apartado 644, Bilbao E-48080 (Spain); Moreno, J. Esteban; Peremarch, C. Pérez-Jorge; Pérez, M. Martínez [Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, Av. Reyes Católicos 2, Madrid 28040 (Spain)

    2016-03-30

    Graphical abstract: - Highlights: • Ca, P and I doped TiO{sub 2} coatings were developed by means of plasma electrolytic oxidation (PEO) technique. • Microstructure and chemical composition of the developed coating were in depth analyzed. • The effect of wear-corrosion synergy was studied through tribocorrosion tests. • Antibacterial efficiency of iodine as biocide agent was analyzed by means of bacterial adhesion study. • A TiO{sub 2} coating with improved wear-corrosion resistance, suitable surface for cell adhesion and biocide properties was achieved. - Abstract: In hip joint implants, in particular in the stems, wear-corrosion effects can accelerate the degradation of the biomaterial. The lack of osseointegration and the risk of contracting implant-associated infections may be other reasons for a premature failure of the implant. In this work, TiO{sub 2} coatings have been developed by means of plasma electrolytic oxidation (PEO) technique in order to achieve wear-resistant hard coatings with osseointegration ability and biocide characteristics. During the PEO process, elements that favor cell growth, like Ca and P, were introduced into the coating. With the purpose of providing the coating with antibacterial properties iodine was added like biocide agent. The microstructure and chemical composition of the developed coatings were analyzed in order to see if the surface of the films was suitable for the cell attachment. The effect of wear-corrosion synergy was studied by means of tribocorrosion tests. Finally, the biocide capacity of iodine against Staphylococcus aureus and Staphylococcus epidermidis was analyzed through bacterial adhesion tests. High wear and corrosion resistance was shown in one of the developed coatings. The achieved surface microstructures seem to be appropriate to improve the osseointegration with proper pore size and porosity index. The antibacterial capacity of iodine was confirmed for S. epidermidis.

  20. Bioactivity studies on TiO₂-bearing Na₂O-CaO-SiO₂-B₂O₃ glasses.

    Science.gov (United States)

    Jagan Mohini, G; Sahaya Baskaran, G; Ravi Kumar, V; Piasecki, M; Veeraiah, N

    2015-12-01

    Soda lime silica borate glasses mixed with different concentrations of TiO2 are synthesized by the melt-quenching technique. As a part of study on bioactivity of these glasses, the samples were immersed in simulated body fluid (SBF) solution for prolonged times (~21 days) during which weight loss along with pH measurements is carried out at specific intervals of time. The XRD and SEM analyses of post-immersed samples confirm the formation of crystalline hydroxyapatite layer (HA) on the surface of the samples. To assess the role of TiO2 on the formation of HA layer and degradability of the samples the spectroscopic studies viz. optical absorption and IR spectral studies on post- and pre-immersed samples have been carried out. The analysis of the results of degradability together with spectroscopic studies as a function of TiO2 concentration indicated that about 6.0 mol% of TiO2 is the optimal concentration for achieving better bioactivity of these glasses. The presence of the maximal concentration octahedral titanium ions in this glass that facilitates the formation of HA layer is found to be the reason for such a higher bioactivity. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. {sup 48}Ti(n,xnpa{gamma}) reaction cross sections using spallation neutrons for E{sub n} = 1 to 20 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Cooper, J R; Hoffman, R D; Younes, W; Devlin, N; Fotiades, N; Nelson, R O

    2005-01-06

    {gamma}-ray excitation functions have been measured for the interaction of fast neutrons with {sup 48}Ti (neutron energy from 1 MeV to 250 MeV). The Los Alamos National Laboratory spallation neutron source, at the LANSCE/WNR facility, provided a ''white'' neutron beam which is produced by bombarding a natural W target with a pulsed proton beam. The prompt-reaction {gamma} rays were measured with the large-scale Compton-suppressed Ge spectrometer, GEANIE. Neutron energies were determined by the time-of-flight technique. Excitation functions were converted to partial {gamma}-ray cross sections, taking into account the dead-time correction, the target thickness, the detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data analysis is presented here for neutron energies between 1 to 20 MeV. Partial {gamma}-ray cross sections for transitions in {sup 47,48}Ti, {sup 48}Sc, and {sup 45}Ca have been determined. These results are compared to Hauser-Feshbach predictions calculated using the STAPRE code, which includes compound nuclear and pre-equilibrium emission. The partial cross sections for {gamma} rays, whose discrete {gamma}-ray cascade path leads to the ground state in {sup 48}Ti, {sup 47}Ti, {sup 48}Sc, and {sup 45}Ca have been summed to obtain estimates of the lower limits for reaction cross sections. Partial cross sections for unobserved {gamma}-rays are predicted from the STAPRE code. These lower limits are combined with Hauser-Feshbach calculations to deduce {sup 48}Ti(n,n'){sup 48}Ti, {sup 48}Ti(n,2n){sup 47}Ti, {sup 48}Ti(n,p){sup 48}Sc, and {sup 48}Ti(n,{alpha}){sup 45}Ca reaction channel cross sections.

  2. Microwave dielectric properties of CaCu{sub 3}Ti{sub 4}O{sub 12}-Al{sub 2}O{sub 3} composite

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Mohd Fariz Ab; Abu, Mohamad Johari; Zaman, Rosyaini Afindi; Ahmad, Zainal Arifin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Karim, Saniah Ab; Mohamed, Julie Juliewatty, E-mail: juliewatty.m@umk.edu.my [Advance Materials Research Cluster, Faculty of Earth Sciences, Universiti Malaysia Kelantan, Jeli Campus, 17600 Jeli, Kelantan (Malaysia); Ain, Mohd Fadzil [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2016-07-19

    (1-x)CaCu{sub 3}Ti{sub 4}O{sub 12} + (x)Al{sub 2}O{sub 3} composite (0 ≤ x ≤0.25) was prepared via conventional solid-state reaction method. The fabrication of sample was started with synthesizing stoichiometric CCTO from CaCO{sub 3}, CuO and TiO{sub 2} powders, then wet-mixed in deionized water for 24 h. The process was continued with calcined CCTO powder at 900 °C for 12 h before sintered at 1040 °C for 10 h. Next, the calcined CCTO powder with different amount of Al{sub 2}O{sub 3} were mixed for 24 h, then palletized and sintered at 1040 °C for 10. X-ray diffraction analysis on the sintered samples showed that CCTO powder was in a single phase, meanwhile the trace of secondary peaks which belong to CaAl{sub 2}O{sub 4} and Corundum (Al{sub 2}O{sub 3}) could be observed in the other samples Scanning electron microscopy analysis showed that the grain size of the sample is firstly increased with addition of Al{sub 2}O{sub 3} (x = 0.01), then become smaller with the x > 0.01. Microwave dielectric properties showed that the addition of Al{sub 2}O{sub 3} (x = 0.01) was remarkably reduced the dielectric loss while slightly increased the dielectric permittivity. However, further addition of Al{sub 2}O{sub 3} was reduced both dielectric loss and permittivity at least for an order of magnitude.

  3. Metastable Phase Relations in the System Ca(sub O)-Al2(sub O)3-MgO-TiO(sub 2): Applications to Ca- And Al-Rich Inclusions

    Science.gov (United States)

    Keller, L. P.; Han, J.

    2017-01-01

    Introduction: High temperature phases such as corundum, hibonite, grossite, and perovskite are among the earliest phases that condensed in the early solar nebula. Recent work has shown that defect-structured phases occur in some ultrarefractory inclusions as metastable, possibly more kinetically-favored alternatives to the thermodynamically predicted stable phase assemblages [1-4]. For example, Han et al. have shown that non-stoichiometry in hibonite is accommodated by extra "spinel" blocks in the structure instead of the equilibrium assemblages hibonite+corundum or hibonite+spinel. To explore these relations, we have conducted a series of experiments in the system CaO-Al2O3- MgO-TiO2. Here we discuss the compositions and mineralogy of the experimental samples and how they relate to phases in refractory inclusions with a focus on perovskite and spinel. Methods: For the series of annealing studies, a CaO-Al2O3 eutectic melt is allowed to react with a pure alumina crucible at 1,530degC for either 4 hours or 5 days, followed by quenching in air. Later experiments were similar except that additions of 5 wt% MgO, and CaTiO(sub 3) were used to explore the effect of minor elements on the phase assemblages. The experimental conditions resulted in reaction zones approximately 100-300 ?m wide consisting of a hibonite layer immediately adjacent to the corundum, followed by a grossite layer, and finally krotite with residual quenched melt. For the experiments with Mg, spinel is distributed in all layers but is mainly concentrated in the krotite layer. In the Ti-bearing experiments, perovskite precipitated in association with the krotite and residual melt. In addition to the experiments, we also analyzed perovskite grains in the FUN inclusion SHAL [5] and a large compact type A CAI from Allende. The experiments and refractory inclusions were analyzed using a JEOL 7600F SEM and quantitative analyses were obtained using the JEOL 8530F field-emission electron microprobe.

  4. EIS, Mott Schottky and EFM analysis of the electrochemical stability and dielectric properties of Ca-P-Ag and Ca-P-Si-Ag coatings obtained by plasma electrolytic oxidation in Ti6Al4V

    Directory of Open Access Journals (Sweden)

    Sara María Leal-Marin

    2017-01-01

    Full Text Available El Ti6Al4V ELI (ASTM F136 es una de las aleaciones más empleadas en dispositivos de osteosíntesis y reemplazo articular. Sin embargo, las propiedades de esta aleación pueden ser mejoradas respecto a su biocompatibilidad y osteointegración con el tejido óseo a través de recubrimientos. El objetivo de este trabajo fue evaluar el comportamiento electroquímico de un recubrimiento obtenido por oxidación por plasma electrolítico sobre Ti6Al4V ELI empleando soluciones electrolíticas enriquecidas con iones de PO4 2-, Ca+2, Si+4 y varias concentraciones de Ag+1. Los recubrimientos se caracterizaron mediante espectroscopia de impedancia electroquímica (EIS y Mott-Schottky (M-S en una celda de tres electrodos con una solución fisiológica simulada. El comportamiento electroquímico se contrastó con microscopía de fuerza electrostática (EFM, donde se analizó el potencial eléctrico del recubrimiento. Los resultados de EIS mostraron mejores propiedades de estabilidad frente a la corrosión en los sustratos recubiertos con Ca- P-Ag, comparados con los recubiertos con Ca-P-Si-Ag. Los espectros de Nyquist y Bode mostraron relajaciones relacionadas con la transferencia de carga hacia la doble capa electroquímica como reflejo de los cambios microestructurales y de conductividad de los recubrimientos, dada por la presencia particular en cada caso, de los elementos contenidos en estos. De acuerdo con los resultados de M-S, todas las muestras ensayadas presentaron un comportamiento con dopado tipo n, cuya conductividad incrementó con la inclusión de plata. Mediante EFM se observaron mayores contrastes en el potencial, fase y la amplitud de los recubrimientos con mayor cantidad de plata respecto al Ti6Al4V sin recubrir.

  5. Enhancement of luminescence intensity and spectroscopic analysis of Eu3+-activated and Li+ charge-compensated CaTiO3 color tunable phosphors for solid-state lighting

    Science.gov (United States)

    Singh, Dhananjay Kr.; Baitha, Pankaj Kr.; Manam, J.

    2016-07-01

    The present work explores a well-crystallized perovskite calcium titanate (CaTiO3) doped with trivalent europium (Eu3+) and co-doped with lithium ion (Li+) successfully synthesized by a conventional solid-state reaction method, and the impact of single dopant and co-dopant on the photoluminescence performances of the sample has been investigated by emission, excitation and diffuse reflectance spectra at the room temperature. Photoluminescence spectra of Li+-doped CaTiO3:Eu3+ nanophosphor revealed at intense pink emission peak for Ca(0.85- y)Li y TiO3:0.15Eu3+ nanophosphor around wavelength 619 nm in the visible region upon the excitation of near-UV light at wavelength 397 nm due to 5 D 0 → 7 F 2 transition in Eu3+. The incorporation of Li+ ion on CaTiO3:Eu3+ nanophosphors enhanced the emission probability from higher 5 D 0 state to lower 7 F j state, and its PL intensity is found to be three times greater than the intensity of CaTiO3:Eu3+ nanophosphor. The spectral characteristics and the Eu-O ligand behavior were confirmed in light of Judd-Ofelt theory from the Emission spectra rather than absorption spectra. Their crystal structure was confirmed by X-ray diffraction (XRD) which is in good agreement with pure orthorhombic phase with space group Pbnm, and it also indicated that the incorporation of the dopant/co-dopant did not affect the crystal structure. The experimental observation reveals that the developed phosphor material Li+-co-doped CaTiO3:Eu3+ can be used in solid-state lighting devices.

  6. Fotoluminescência e adsorção de CO2 em nanopartículas de CaTiO3 dopadas com lantânio

    Directory of Open Access Journals (Sweden)

    Gonçalves Rosana F.

    2004-01-01

    Full Text Available Ca1-xLa xTiO3 powders were prepared by the polymeric precursor method. X-ray diffraction (XRD, FT-Raman spectroscopy, transmission electron microscopy (TEM, and N2 and CO2 adsorption were used for the microstructural and surface characterization of the powders. Room temperature photoluminescence (PL was observed in Ca1-xLa xTiO3 amorphous particles. The PL intensity of these powders was found to be dependent on the lanthanum molar concentration.

  7. Isospin diffusion in binary collisions of 32S+Ca,4840 and 32S+48Ti at 17.7 MeV/nucleon

    Science.gov (United States)

    Piantelli, S.; Valdré, S.; Barlini, S.; Casini, G.; Colonna, M.; Baiocco, G.; Bini, M.; Bruno, M.; Camaiani, A.; Carboni, S.; Cicerchia, M.; Cinausero, M.; D'Agostino, M.; Degerlier, M.; Fabris, D.; Gelli, N.; Gramegna, F.; Gruyer, D.; Kravchuk, V. L.; Mabiala, J.; Marchi, T.; Morelli, L.; Olmi, A.; Ottanelli, P.; Pasquali, G.; Pastore, G.

    2017-09-01

    The systems 32S+Ca,4840 and 32S+48Ti at 17.7 MeV/nucleon were investigated with the setup general array for fragment identification and for emitted light particles in dissipative collisions (GARFIELD) plus ring counter (RCo) at Laboratori Nazionali di Legnaro (LNL) of Istituto Nazionale di Fisica Nucleare (INFN). Fusion evaporation (FE), fusion fission (FF), and deep inelastic (DIC) events were identified, also through the comparison with the prediction of a transport model (stochastic mean field, SMF), coupled to GEMINI++ as an afterburner. This work mainly deals with the study of isospin transport phenomena in DIC events. In particular, the isospin diffusion is highlighted by comparing the average isotopic content of the quasiprojectile (QP) remnants observed when the target is the N =Z nucleus 40Ca and when it is the neutron-rich 48Ca. Also, the d /p and t /p ratios for particles forward emitted with respect to the QP were found to increase with increasing N /Z of the target.

  8. S-C Mylonites

    NARCIS (Netherlands)

    Lister, G.S.; Snoke, A.W.

    1984-01-01

    Two types of foliations are commonly developed in mylonites and mylonitic rocks: (a) S-surfaces related to the accumulation of finite strain and (b) C-surfaces related to displacement discontinuities or zones of relatively high shear strain. There are two types of S-C mylonites. Type I S-C

  9. Species Composition (SC)

    Science.gov (United States)

    John F. Caratti

    2006-01-01

    The FIREMON Species Composition (SC) method is used to provide ocular estimates of cover and height measurements for plant species on a macroplot. The SC method provides plant species composition and coverage estimates to describe a stand or plant community and can be used to document changes over time. It is suited for a wide variety of vegetation types and is...

  10. Crystal structure and electrical conductivity of lanthanum-calcium chromites-titanates La 1-xCa xCr 1-yTi yO 3-δ ( x=0-1, y=0-1)

    Science.gov (United States)

    Vashook, V.; Vasylechko, L.; Zosel, J.; Gruner, W.; Ullmann, H.; Guth, U.

    2004-10-01

    Five series of perovskite-type compounds in the system La1-xCaxCr1-yTiyO3 with the nominal compositions y = 0 , x = 0 - 0.5 ; y = 0.2 , x = 0.2 - 0.8 ; y = 0.5 , x = 0.5 - 1.0 ; y = 0.8 , x = 0.6 - 1.0 and y = 1 , x = 0.8 - 1 were synthesized by a ceramic technique in air (final heating 1350 °C). On the basis of the X-ray analysis of the samples with (Ca/Ti)⩾1, the phase diagram of the CaTiO3-LaCrIIIO3-CaCrIVO3 quasi-ternary system was constructed. Extended solid solution with a wide homogeneity range is formed in the quasi-ternary system CaCrIVO3-CaTiO3-LaCrIIIO3. The solid solution La(1-x‧-y)Ca(x‧+y)CrIVx‧CrIII(1-x‧-y)TiyO3 exists by up to 0.6-0.7 mol fractions of CaCrIVO3 (x‧ phases with an orthorhombic structure. In the temperature range between 850 and 1000 °C, the synthesized single-phase compositions are stable at pO2=6×10-16-0.21×105 Pa. Oxygen stoichiometry and electrical conductivity of the separate compounds were investigated as functions of temperature and oxygen partial pressure. The chemical stability of these oxides with respect to oxygen release during thermal dissociation decreases with increasing Ca-content. At 900 °C and oxygen partial pressure 1×10-15-0.21×105 Pa, the compounds with x > y (acceptor doped) are p-type semiconductors and those with x < y (donor doped) and x = y are n-type semiconductors. The type and level of electrical conductivity are functions of the concentration ratios of cations occupying the B-sites of the perovskite structures: [Cr3+]/[Cr4+] and [Ti4+]/[Ti3+]. The maximum electrical conductivity at 900 °C and pO2=10-15 Pa was found for the composition La0.1Ca0.9TiO3 (near 50 S/cm) and in air at 900 °C for La0.5Ca0.5CrO3 (close to 100 S/cm).

  11. Static current models in Co2+ and Ti4+ substituted M-type CaCoxTixFe(12-2x)O19 ferrite

    Science.gov (United States)

    Kaur, Rajneesh; Singh, Charanjeet; Bhikhan, Vikas; Jaroszewski, Maciej; Bindra Narang, S.

    2015-10-01

    The static current density ( J)-electric field ( E) characteristics of CaCo x Ti x Fe(12-2 x)O19 ferrite ( x = 0.1,0.2,0.3,0.4,0.5,0.6,0.7) have been investigated from 0.06 kV/m to 4.10 kV/m at room temperature. Ohmic behavior is present in compositions x = 0.1,0.2,0.4,0.5,0.6,0.7 at low applied field, whereas non linearity in J- E curves is defined at higher applied region in compositions x = 0.2,0.3,0.4,0.7. The role of various conduction mechanisms Schottky, Poole-Frenkel, Ionic Hopping and Space Charge Limited Current mechanisms has been discussed.

  12. Effects of the volume ratio of water and ethanol on morphosynthesis and photocatalytic activity of CaTiO3 by a solvothermal process

    Science.gov (United States)

    Dong, Weixia; Song, Bin; Zhao, Gaoling; Meng, Weijie; Han, Gaorong

    2017-05-01

    Solvothermal production of large surface area, dendritic CaTiO3 crystals exhibiting enhanced photocatalytic activity is facilitated through careful control of the volume ratio of water and ethanol in high pH (≥12) samples. The study was performed without the use of templates or surfactants. Results show the volume ratio of water and ethanol had significant effect on sample morphosynthesis. Depending on solvent ratios, results ranged from imperfect dendrites, to four-arm petal-like dendrites, four-arm dendrites mixed with butterfly-like dendrites, and regular and aggregated prisms. Results show the four-arm dendritic sample exhibiting superior photocatalytic activity arising from a unique morphology and large surface area capable of enhanced light harvesting.

  13. Enhancement of dielectric constant at percolation threshold in CaCu3 Ti4 O12 ceramic fabricated by both solid state and sol-gel process

    Science.gov (United States)

    Mukherjee, Rupam; Garcia, Lucia; Lawes, Gavin; Nadgorny, Boris

    2014-03-01

    We have investigated the large dielectric enhancement at the percolation threshold by introducing metallic RuO2 grains into a matrix of CaCu3Ti4O12 (CCTO). The intrinsic response of the pure CCTO samples prepared by solid state and sol-gel processes results in a dielectric constant on the order of 104 and 103 respectively with low loss. Scanning electron microscopy and energy dispersive x-ray spectroscopy indicate that a difference in the thickness of the copper oxide enriched grain boundary is the main reason for the different dielectric properties between these two samples. Introducing RuO2 metallic fillers in these CCTO samples yields a sharp increase of the dielectric constant at percolation threshold fc, by a factor of 6 and 3 respectively. The temperature dependence of the dielectric constant shows that the dipolar relaxation plays an important role in enhancing dielectric constant in composite systems.

  14. Intermediate temperature ionic conductivity of Sm1.92Ca0.08Ti2O7–δ pyrochlore

    DEFF Research Database (Denmark)

    Eurenius, Karinh E. J.; Bentzer, Henrik Karnøe; Bonanos, Nikolaos

    2011-01-01

    The results of concentration cell electromotive force methods (EMF) and electrochemical impedance spectroscopy measurements on the pyrochlore system Sm1.92Ca0.08Ti2O7–δ are presented. The data have been used to estimate total and partial conductivities and determine transport numbers for protons...... and oxide ions under various conditions. The EMF techniques employed include corrections for electrode polarisation resistance. The measurements were performed using wet and dry atmospheres in a wide range using mixtures of H2, N2, O2, and H2O in the temperature region where proton conductivity was expected...... (500–300 °C). The impedance measurements revealed the conductivity to be mainly ionic under all conditions, with the highest total conductivity measured being 0.045 S/m under wet oxygen at 500 °C. Both bulk and grain boundary conductivity was predominantly ionic, but electronic conductivity appeared...

  15. Ferroelectric Properties of CaBi4Ti4O15 Thin Films on Ito/glass Substrates Prepared by Sol-Gel Technology

    Science.gov (United States)

    Cheng, Chien-Min; Kuan, Ming-Chang; Chen, Kai-Hunag; Tsai, Jen-Hwan

    In this study, ferroelectric CaBi4Ti4O15 (CBT) thin films prepared by sol-gel method and deposited on ITO/glass substrates for applications in system-on-panel (SOP) devices were fabricated and investigated. The electrical and physical characteristics of as-deposited and annealed CBT thin films for metal-ferroelectric-metal (MFM) structures was discussed and investigated. In addition, the ferroelectric properties in annealed CBT thin films on ITO/glass substrate showed and exhibited clear polarization versus electrical field curves. From p-E curves, the 2Pr value and coercive field of annealed CBT thin films were calculated to be 10μC/cm2 and 180 kV/cm, respectively. Finally, the maximum capacitance, leakage current density, and transmittance within the ultraviolet-visible (UV-vis) spectrum were also investigated and discussed.

  16. Effect of oxygen partial pressure on structural and optical properties of pulsed laser deposited CaBi4Ti4O15 thin films

    Science.gov (United States)

    Emani, Sivanagi Reddy; Raju, K. C. James

    2017-03-01

    The influence of oxygen partial pressure (OPP) on the structural and optical properties of CaBi4Ti4O15 (CBTi) thin films deposited by pulsed laser deposition have been investigated in the range of 0.1 mbar to 7.8 × 10-3 mbar. The structural properties show all the films are polycystlline in nature with orthorombic structure. The optical transmission of the films is in the range of 60-90%. A slight shift in transmission threshold towards higher wavelength region with an increase in O2 pressure reveals the systematic reduction in the optical band gap energy (3.69 to 3.59 eV) of the films. Raman studies confirm the phase formation and presence of stresses in the films. It is suggested that the OPP played a key role in controlling crystallinity, morphology, chemical composition and optical properties in CBTi thin films.

  17. Ferroelectric properties of alkoxy-derived CaBi4Ti4O15 thin films on Pt-passivated Si

    Science.gov (United States)

    Kato, Kazumi; Suzuki, Kazuyuki; Nishizawa, Kaori; Miki, Takeshi

    2001-02-01

    CaBi4Ti4O15 (CBTi144) thin films were prepared by spin coating a precursor solution of metal alkoxides. As-deposited thin films began crystallization below 550 °C and reached full crystallinity of a single phase of layered perovskite at 650 °C via rapid thermal annealing in oxygen. The 650 °C annealed CBTi144 thin film showed random orientation on Pt-passivated Si substrate and exhibited P-E hysteresis loops. The remanent polarization (Pr) and coercive electric field (Ec) were 9.4 μC/cm2 and 106 kV/cm, respectively, at 11 V. The dielectric constant and loss factor were 300 and 0.033, respectively, at 100 kHz.

  18. Phase transition, ferroelectric, and dielectric properties of layer-structured perovskite CaBi3Ti3O12-δ thin films

    Science.gov (United States)

    Kato, Kazumi; Suzuki, Kazuyuki; Nishizawa, Kaori; Miki, Takeshi

    2001-07-01

    Thin films of a bismuth-based layer-structured perovskite compound with a number of oxygen octahedron along the c axis between Bi-O layers of three, CaBi3Ti3O12-δ, were prepared using a mixture solution of complex alkoxides. The films crystallized below 550 °C. The crystal structure and surface morphology of these films changed between 600 and 650 °C. The 650 °C-annealed thin film consisted of well-developed grains and exhibited polarization-electric hysteresis loops. The remanent polarization and coercive electric field were 8.5 μC/cm2 and 124 kV/cm, respectively, at 7 V. The dielectric constant and loss factor were about 250 and 0.048, respectively, at 100 kHz.

  19. Optical and microwave properties of CaBi4Ti4O15 ferroelectric thin films deposited by pulsed laser deposition

    Science.gov (United States)

    Emani, Sivanagi Reddy; Joseph, Andrews; Raju, K. C. James

    2016-05-01

    Transparent CaBi4Ti4O15 (CBTi) ferroelectric thin films are deposited by pulsed laser deposition method. The structural, optical and microwave dielectric properties were investigated. CBTi thin films had polycrystalline bismuth-layered perovskite structure and exhibited excellent optical properties. The X-ray analysis of the thin film demonstrates the phase formation and crystallinity. The optical transmission studies show that film is transparent in VIS-NIR region with a direct band gap of 3.53 EV. Morphological studies provide surface roughness as 3 mm. Dielectric constant and loss factors were 48 and 0.060 respectively, at 10GHz. These results suggest that CBTi thin films are promising multifunctional materials for applications in optoelectronic and microwave devices.

  20. Structure and piezoelectric properties of 1-μm-thick polar-axis-oriented CaBi4Ti4O15 films

    Science.gov (United States)

    Kato, K.; Tanaka, K.; Kayukawa, S.; Suzuki, K.; Masuda, Y.; Kimura, T.; Nishizawa, K.; Miki, T.

    2007-06-01

    1-μm-thick polar-axis-oriented CaBi4Ti4O15 (CBTi144) films were fabricated by control of nucleation and growth in alkoxy-derived non-crystalline layers on Pt foils. The oxygen ambient during pre-baking impacted both the cross-sectional microstructure and the crystallographic orientation. The 1-μm-thick film showed relatively high intensities of (100)/(010) diffraction lines in the X-ray diffraction profile and simultaneously had a closely packed dense structure in the transmission electron microscopy cross-sectional profile. Resultantly, the leakage current density decreased to about 7×10-8 A/cm2 at 10 V. The piezoelectric constant d33 was determined to be 260 pm/V at a maximum poling voltage of 60 V by measurements using piezoelectric force microscopy.

  1. Impact of oxygen ambient on ferroelectric properties of polar-axis-oriented CaBi4Ti4O15 films

    Science.gov (United States)

    Kato, Kazumi; Tanaka, Kiyotaka; Suzuki, Kazuyuki; Kimura, Tatsuo; Nishizawa, Kaori; Miki, Takeshi

    2005-03-01

    Polar-axis oriented CaBi4Ti4O15(CBTi144) films were fabricated on Pt foils using a complex metal alkoxide solution. The oxygen ambient during crystallization of the films impacted the crystal perfection, crystallite size, and the ferroelectric properties. The 500mm thick film crystallized in oxygen flow had single columnar structure and in-plane grain size of about 200nm. The Scherrer's crystallite diameter was calculated as about 110nm. The ferroelectric properties were improved. The Pr and Ec of the film enhanced as 33.6μC /cm2 and 357kV /cm, respectively, at an applied voltage of 50V. Voltage applied for full polarization switching was lowered by controlling oxygen stoichiometry of the film. Indeed, the polar-axis-oriented CBTi144 films would open up possibilities for devices as Pb-free ferroelectric materials.

  2. Structure and ferro-/piezoelectric properties of bimorph-shape CaBi4Ti4O15 films on Pt foils

    Science.gov (United States)

    Kato, K.; Tanaka, K.; Suzuki, K.; Kimura, T.; Nishizawa, K.; Miki, T.

    2005-04-01

    In-plane c-axis oriented CaBi4Ti4O15 (CBTi144) films were fabricated on Pt foils using a complex metal alkoxide solution. The a/b-axis orientation of the ferroelectric films was affected by the preferred orientation of Pt foil, which is associated with the thickness. The 500 nm-thick CBTi144 films showed good ferro- and piezoelectric properties on 0.010 mm-thick Pt foils. The Pr and Ec were 26 μC/cm2 and 230 kV/cm, respectively, at an applied voltage of 75 V. The d33 was characterized as 25-34 pm/V by piezoresponse force microscopy. The values enhanced compared to those of the CBTi144 thin film with random orientation. The polar-axis oriented CBTi144 films would open for novel devices as Pb-free piezoelectric materials.

  3. Competing strain relaxation mechanisms in epitaxially grown Pr0.48Ca0.52MnO3 on SrTiO3

    Directory of Open Access Journals (Sweden)

    Anja Herpers

    2014-10-01

    Full Text Available We investigated the impact of strain relaxation on the current transport of Pr0.48Ca0.52MnO3 (PCMO thin films grown epitaxially on SrTiO3 single crystals by pulsed laser deposition. The incorporation of misfit dislocations and the formation of cracks are identified as competing mechanisms for the relaxation of the biaxial tensile strain. Crack formation leads to a higher crystal quality within the domains but the cracks disable the macroscopic charge transport through the PCMO layer. Progressive strain relaxation by the incorporation of misfit dislocations, on the other hand, results in a significant decrease of the activation energy for polaron hopping with increasing film thickness.

  4. Polymorphic phase transition and morphotropic phase boundary in Ba1- x Ca x Ti1- y Zr y O3 ceramics

    Science.gov (United States)

    Abdessalem, M. Ben; Aydi, S.; Aydi, A.; Abdelmoula, N.; Sassi, Z.; Khemakhem, H.

    2017-09-01

    This paper deals with Ca and Zr co-doped BaTiO3 (BCTZ( x, y)) ( x = 0.1, 0.13, 0.2 and y = 0.05, 0.1, 0.15). These ceramics were prepared using the conventional solid state method. The symmetry, dielectric properties, Raman spectroscopy, ferroelectric behavior and piezoelectric effect were examined. X-ray diffraction (XRD) results display that morphotropic boundary occurs from tetragonal to orthorhombic region of BCZT( x=0.1, 0.2, y=0.05, 0.1) and polymorphic phase transitions from tetragonal to orthorhombic, orthorhombic to rhombohedral regions of BCZT( x=0.13, y=0.1). The evolution of the Raman spectra was investigated as a function of compositions at room temperature, in correlation with XRD analysis and dielectric measurements. We note that the substitution of Ca in Ba site and Zr ions in Ti site slightly decreased the cubic-tetragonal temperature transition ( T C) and increased the orthorhombic-tetragonal ( T 1) and rhombohedral-orthorhombic ( T 2) temperatures transitions. The ferroelectric properties were examined by a P- E hysteresis loop. The two parameters Δ T 1 and Δ T 2 are defined as Δ T 1 = T C - T 1 and Δ T 2 = T C - T 2, they come close to T C for x = 0.13, y = 0.1, which reveals that this composition is around the polymorphic phase. The excellent piezoelectric coefficient of d 33 = 288 pC N-1, the electromechanical coupling factor k p = 40%, high constant dielectric 9105, coercive field E c = 0.32 (KV mm-1) and remanent polarization P r = 0.1 (µc mm-2) were obtained for composition x = 0.13, y = 0.1.

  5. High efficiency angular non-critical phase matching for Ti:sapphire laser realized on LaCa4O(BO3)3 single crystals

    Science.gov (United States)

    Liu, Y. Q.; Yu, F. P.; Qi, H. W.; Han, S.; Zhang, F.; Wang, Z. P.; Yu, X. Q.; Zhao, X.; Xu, X. G.

    2014-09-01

    Angular non-critical phase-matching (A-NCPM) second harmonic generation (SHG) for a Ti:sapphire laser was realized on LaCa4O(BO3)3 (LaCOB) single crystals, grown by the Czochralski pulling method. Properties including the wavelength, bandwidth, effective nonlinear optical (NLO) coefficient (deff), and acceptance angle were evaluated. At ambient temperature of 20 °C, the type-I NCPM (808 nm wavelength) was obtained along the y axis of LaCOB crystals, where the effective nonlinear optical coefficient (deff), PM waveband, and angular acceptance were found to be of the order of 0.59 pm/V, 803~818 nm and 50.6 mrad cm1/2 (ΔϕL), respectively. Moreover, high single-pass SHG conversion efficiency (44.6%) was achieved for 24.8 mm long Y-cut samples at 808 nm, using a mode-locked Ti:sapphire fundamental laser.

  6. Exceptionally High Piezoelectric Coefficient and Low Strain Hysteresis in Grain-Oriented (Ba, Ca)(Ti, Zr)O3through Integrating Crystallographic Texture and Domain Engineering.

    Science.gov (United States)

    Liu, Yingchun; Chang, Yunfei; Li, Fei; Yang, Bin; Sun, Yuan; Wu, Jie; Zhang, Shantao; Wang, Ruixue; Cao, Wenwu

    2017-09-06

    Both low strain hysteresis and high piezoelectric performance are required for practical applications in precisely controlled piezoelectric devices and systems. Unfortunately, enhanced piezoelectric properties were usually obtained with the presence of a large strain hysteresis in BaTiO 3 (BT)-based piezoceramics. In this work, we propose to integrate crystallographic texturing and domain engineering strategies into BT-based ceramics to resolve this challenge. [001] c grain-oriented (Ba 0.94 Ca 0.06 )(Ti 0.95 Zr 0.05 )O 3 (BCTZ) ceramics with a texture degree as high as 98.6% were synthesized by templated grain growth. A very high piezoelectric coefficient (d 33 ) of 755 pC/N, and an extremely large piezoelectric strain coefficient (d 33 * = 2027 pm/V) along with an ultralow strain hysteresis (H s ) of 4.1% were simultaneously achieved in BT-based systems for the first time, which are among the best values ever reported on both lead-free and lead-based piezoceramics. The exceptionally high piezoelectric response is mainly from the reversible contribution, and can be ascribed to the piezoelectric anisotropy, the favorable domain configuration, and the formation of smaller sized domains in the BCTZ textured ceramics. This study paves a new pathway to develop lead-free piezoelectrics with both low strain hysteresis and high piezoelectric coefficient. More importantly, it represents a very exciting discovery with potential application of BT-based ceramics in high-precision piezoelectric actuators.

  7. A miniaturized Microwave Bandpass Filter Based on Modified (Mg0.95Ca0.05TiO3 Substrate

    Directory of Open Access Journals (Sweden)

    Hu Mingzhe

    2016-01-01

    Full Text Available A microwave miniaturized bandpass filter using (Mg0.95Ca0.05TiO3 (abbreviated as 95MCT hereafter ceramic substrate is investigated in the present paper. The paper studies the sintering and microwave dielectric properties of Al2O3, La2O3 and SiO2 co-doped 95MCT. The XRD pattern shows that a secondary phase MgTi2O5 is easily segregated in 95MCT ceramic, however, through co-doping it can be effectively suppressed, and the microwave dielectric properties, especially, the Qf value can be significantly improved. Through optimizing the co-doping ratio of Al2O3, La2O3 and SiO2, the sintering temperature of 95MCT ceramic can be lowered by 80°C, and the microwave dielectric properties can reach Qf=61856GHz and εr=19.84, which indicates the modified 95MCT ceramic have a great potential application in microwave communication devices. Based on this, we also designed a miniaturized microwave bandpass filter (BPF on modified 95MCT substrate. Through a full wave electromagnetic structure simulation, the results show that the center frequency of the BPF is 2.45GHz and the relative bandwidth is 4.09% with the insertion loss of less than 0.2dB in the whole bandpass.

  8. Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

    CERN Document Server

    Kim, H J; Yun, H S

    2001-01-01

    A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

  9. Temperature compensation effects of TiO2 on Ca[(Li1/3Nb2/3)0.8Sn0.2]O3‑δ microwave dielectric ceramic

    Science.gov (United States)

    Hu, Mingzhe; Wei, Huanghe; Xiao, Lihua; Zhang, Kesheng; Hao, Yongde

    2017-10-01

    The crystal structure and dielectric properties of TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3‑δ microwave ceramics are investigated in the present paper. The crystal structure is probed by XRD patterns and their Rietveld refinement, results show that a single perovskite phase is formed in TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3‑δ ceramics with the crystal structure belonging to the orthorhombic Pbnm 62 space group. Raman spectra results indicate that the B-site order-disorder structure transition is a key point to the dielectric loss of TiO2-modified Ca[(Li1/3Nb2/3)0.8Sn0.2]O3‑δ ceramics at microwave frequencies. After properly modified by TiO2, the large negative temperature coefficient of Ca[(Li1/3Nb2/3)0.8Sn0.2]O3‑δ ceramic can be compensated and the optimal microwave dielectric properties can reach 𝜀r = 25.66, Qf = 18,894 GHz and TCF = ‑6.3 ppm/∘C when sintered at 1170∘C for 2.5 h, which manifests itself for potential use in microwave dielectric devices for modern wireless communication.

  10. Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation

    Directory of Open Access Journals (Sweden)

    Wennerberg Ann

    2011-03-01

    Full Text Available Abstract Background The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown. Methods We have investigated how the properties of surfaces that may be used on abutments: turned titanium, sol-gel nanoporous TiO2 coated surfaces and anodized Ca2+ modified surfaces, affect biofilm formation by two early colonizers of the oral cavity: Streptococcus sanguinis and Actinomyces naeslundii. The bacteria were detected using 16S rRNA fluorescence in situ hybridization together with confocal laser scanning microscopy. Results Interferometry and atomic force microscopy revealed all the surfaces to be smooth (Sa ≤ 0.22 μm. Incubation with a consortium of S. sanguinis and A. naeslundii showed no differences in adhesion between the surfaces over 2 hours. After 14 hours, the level of biofilm growth was low and again, no differences between the surfaces were seen. The presence of saliva increased the biofilm biovolume of S. sanguinis and A. naeslundii ten-fold compared to when saliva was absent and this was due to increased adhesion rather than biofilm growth. Conclusions Nano-topographical modification of smooth titanium surfaces had no effect on adhesion or early biofilm formation by S. sanguinis and A. naeslundii as compared to turned surfaces or those treated with anodic oxidation in the presence of Ca2+. The presence of saliva led to a significantly greater biofilm biovolume but no significant differences were seen between the test surfaces. These data thus suggest that modification with sol-gel derived nanoporous TiO2, which has been shown to improve osseointegration and soft-tissue healing in vivo, does not cause greater biofilm

  11. Cooperative and competitive adsorption of amino acids with Ca²⁺ on rutile (α-TiO₂).

    Science.gov (United States)

    Lee, Namhey; Sverjensky, Dimitri A; Hazen, Robert M

    2014-08-19

    The interactions of biomolecules such as amino acids with mineral surfaces in the near-surface environment are an important part of the short and long-term carbon cycles. Amino acid-mineral surface interactions also play an important role in biomineralization, biomedicine, and in assembling the building blocks of life in the prebiotic era. Although the pH effects during adsorption of amino acids onto mineral surfaces have been studied, little is known about the effects of environmentally important divalent cations. In this study, we investigated the adsorption of the oppositely charged amino acids glutamate and lysine with and without the addition of divalent calcium. Without calcium, glutamate shows a maximum in adsorption at a pH of ∼4 and lysine shows a maximum in adsorption at a pH of ∼9.4. In comparison, with calcium present, glutamate showed maxima in adsorption at both low and high pH, whereas lysine showed no adsorption at all. These dramatic effects can be described as cooperative adsorption between glutamate and Ca(2+) and as competitive adsorption between lysine and Ca(2+). The origin of these effects can be attributed to electrostatic phenomena. Adsorption of Ca(2+) at high pH makes the rutile surface more positive, which attracts glutamate and repels lysine. Our results indicate that the interactions of biomolecules with mineral surfaces in the environment will be strongly affected by the major dissolved species in natural waters.

  12. Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity.

    Science.gov (United States)

    Yatongchai, Chokchai; Placek, Lana M; Curran, Declan J; Towler, Mark R; Wren, Anthony W

    2015-11-01

    Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability. © The Author(s) 2015.

  13. Structural characterization and physical properties of P2O5-CaO-Na2O-TiO2 glasses by Fourier transform infrared, Raman and solid-state magic angle spinning nuclear magnetic resonance spectroscopies.

    Science.gov (United States)

    Kiani, Azadeh; Hanna, John V; King, Scott P; Rees, Gregory J; Smith, Mark E; Roohpour, Nima; Salih, Vehid; Knowles, Jonathan C

    2012-01-01

    Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0≤x≤5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. A percepção dos gestores operacionais sobre os impactos gerados nos processos de trabalho após a implementação das melhores práticas de governança de TI no TRE/SC

    Directory of Open Access Journals (Sweden)

    Rosangela Klumb

    2014-08-01

    Full Text Available Este estudo objetivou compreender a percepção dos gestores operacionais da Secretaria de Tecnologia da Informação (STI do TRE/SC acerca dos impactos gerados nos processos de trabalho internos do órgão após a implementação das melhores práticas de governança de TI. Em termos metodológicos, trata-se de um estudo de caso descritivo-avaliativo, de abordagem qualitativa no que concerne às características e ao modo de investigação. Como resultados, verificou-se que até março de 2013 foram implementados oito dos 24 processos de governança de TI baseados no modelo Cobit, versão 4.1, definidos como meta do Planejamento Estratégico de TI para 2013. Concluiu-se que a percepção dos gestores é positiva em relação à governança de TI, embora existam algumas falhas, como na comunicação intra e interáreas e na centralização de informações por alguns setores.

  15. The enhancing performance of (Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.90}Zr{sub 0.10})O{sub 3} ceramics by tuning anatase–rutile phase structure

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Xiaolian, E-mail: chaoxl@snnu.edu.cn [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, Shaanxi (China); Wang, Juanjuan [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an710048, Shaanxi (China); Wang, Zhongming; Zhang, Ting [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, Shaanxi (China); Yang, Zupei, E-mail: yangzp@snnu.edu.cn [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi’an, 710062, Shaanxi (China); Li, Guangzhao [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an710048, Shaanxi (China)

    2016-04-15

    Graphical abstract: Titanium dioxide (TiO{sub 2}) with different phase structure had interesting influence on the crystal structure, microstructure, the sintering temperature and electrical properties. - Highlights: • BCZT ceramics were prepared using either anatase or rutile structures as Ti source. • Orthorhombic and tetragonal mixture structure was exhibited by adjusting Ti source. • The optimal properties were observed in BCZT ceramics with rutile titanium dioxide. - Abstract: To research effect of raw materials TiO{sub 2} with the phase structures on the crystal structure, microstructure and electrical properties of lead-free (Ba{sub 0.85}Ca{sub 0.15})(Ti{sub 0.90}Zr{sub 0.10})O{sub 3} (BCZT) ceramics, BCZT ceramics using either anatase or rutile as Ti source were synthesized by solid-state reaction. Titanium dioxide (TiO{sub 2}) with anatase/rutile phase structures had interesting influence on the crystal structure, microstructure and the sintering temperature by the X-ray diffraction and SEM, which also played an important role in improved electrical properties. The BCZT ceramics with rutile titanium dioxide demonstrated optimal piezoelectric and dielectric properties: d{sub 33} = 590 pC/N, k{sub p} = 0.46, ε{sub r} = 2810, tanδ = 0.014 and T{sub c} = 91 °C, which was obviously superior to BCZT ceramics with anatase titanium dioxide.

  16. Assessment of CaSO{sub 4}:Dy and LiF:Mg,Ti thermoluminescent dosimeters performance in the dosimetry of clinical electron beams; Avaliacao do desempenho dos detectores termoluminesncetes de CaSO{sub 4}:Dy e LiF:Mg,Ti na dosimetria de feixes clinicos de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, Maira Goes

    2008-07-01

    The assessment of the performance of CaS0{sub 4}:Dy thermoluminescent detectors produced by IPEN in the dosimetry of clinical electron beams aims to propose an alternative to the LiF:Mg,Ti commercial dosimeters (TLD-100) largely applied in radiation therapy. The two types of thermoluminescent dosimeters were characterised with the use of PMMA, RMI-457 type solid water and water phantoms in radiation fields of 4, 6, 9, 12 and 16 MeV electrons of nominal energies in which the dose-response curves were obtained and the surface and depth doses were determined. The thermoluminescent response dependency with the electron nominal energies and the applied phantom were studied. The CaS0{sub 4}:Dy presented the same behaviour than the LiF:Mg,Ti in such a way that its application as an alternative to the TLD-100 pellets in the radiation therapy dosimetry of electron beams is viable and presents the significantly higher sensitivity to the electron radiation as its main advantage. (author)

  17. Influences of TiO2 Addition on the Crystallization Behavior, Microstructure, and Magnetic Properties of Li2O-MnO2-Fe2O3-CaO-P2O5-SiO2 Glasses

    Science.gov (United States)

    Cheng, Huy-Zu; Lin, Huey-Jiuan; Wang, Moo-Chin; Wang, Chien-Fa; Hsi, Chi-Shiung; Zhao, XiuJian; Jiang, Hong; Li, Chang-Jiu; Lu, Peng

    2015-05-01

    Influences of TiO2 addition on the phase transformation, microstructure, and magnetic properties of Li2O-MnO2-Fe2O3-CaO-P2O5-SiO2 (LMFCPS) glass have been studied using DTA, XRD, SEM, EDS, TEM, SAED, and SQUID. When LMFCPS glass, with and without TiO2 content, is crystallized at 1123 K (850 °C) for 2 hours, the magnetite (FeFe2O4), β-wollastonite (β-CaSiO3), lithium orthophosphate (Li3PO4), and triphylite (Li(Mn0.5Fe0.5)PO4) phases are formed. The β-wollastonite and lithium silicate formed with evident directionality were observed in the LMFCPS glass-ceramics without adding TiO2. However, when the LMFCPS glass with various TiO2 content is crystallized at 1123 K (850 °C) for 16 hours, very small remnant magnetic induction and coercive field hysteresis loops were found showing the ferromagnetic property in a magnetic field smaller than 2000 Oe. Additionally, when LMFCPS glass with various TiO2 contents is crystallized at 1123 K (850 °C) for 16 hours, the glass-ceramics showed super-paramagnetic property in a magnetic field of 60 kOe due to the small grains of the iron-rich phases.

  18. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    Science.gov (United States)

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. The high-temperature modification of ScRuSi - Structure, 29Si and 45Sc solid state NMR spectroscopy

    Science.gov (United States)

    Hoffmann, Rolf-Dieter; Rodewald, Ute Ch.; Haverkamp, Sandra; Benndorf, Christopher; Eckert, Hellmut; Heying, Birgit; Pöttgen, Rainer

    2017-10-01

    A polycrystalline sample of the TiNiSi type low-temperature (LT) modification of ScRuSi was synthesized by arc-melting. Longer annealing in a sealed silica tube (6 weeks at 1270 K) followed by quenching led to the high-temperature (HT) phase. HT-ScRuSi adopts the ZrNiAl structure type: P 6 bar 2 m , a = 688.27(9), c = 336.72(5) pm, wR2 = 0.0861, 260 F2 values, 14 variables. The striking structural building units are regular, tricapped trigonal prisms Si1@Ru3Sc6 and Si2@Ru6Sc3. Both polymorphs have been characterized by 29Si and 45Sc MAS-NMR spectroscopy. The local scandium environments in the two polymorphs are easily distinguished by their electric field gradient tensor values, in agreement with theoretically calculated values.

  20. Cubic-tetragonal phase transition in Ca sub 0 sub . sub 0 sub 4 Sr sub 0 sub . sub 9 sub 6 TiO sub 3 a combined specific heat and neutron diffraction study

    CERN Document Server

    Gallardo, M C; Romero, F J; Cerro, J D; Seifert, F; Redfern, S A T

    2003-01-01

    The specific heat corresponding to the tetragonal-to-cubic transition in Ca sub 0 sub . sub 0 sub 4 Sr sub 0 sub . sub 9 sub 6 TiO sub 3 perovskite has been measured by conduction calorimetry. The order parameter of the transition has been obtained by means of neutron diffraction at low temperatures. Comparison of calorimetric data with the evolution of the order parameter indicates that this transition seems to follow a mean field Landau potential as in SrTiO sub 3. The linear behaviour of the excess of entropy versus temperature suggests that a 2-4 Landau potential is sufficient to describe the transition.

  1. Effect of Ca{sup 2+} substitution on impedance and electrical conduction mechanism of Ba{sub 1−x}Ca{sub x}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (0.00≤x≤0.20) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Tanusree [Functional Ceramics Laboratory, Department of Applied Physics, Indian Institute of Technology (ISM), Dhanbad 826004 (India); Das, Sayantani [Department of Physics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Badapanda, T. [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar, Odisha 7520544 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Sarun, P.M., E-mail: sarun.res@gmail.com [Functional Ceramics Laboratory, Department of Applied Physics, Indian Institute of Technology (ISM), Dhanbad 826004 (India)

    2017-03-01

    The Ca modified Ba{sub 1−x}Ca{sub x}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (BCZT) system for x=0.00–0.20 is synthesized by the high-temperature conventional solid state reaction method. The morphotropic phase boundary (MPB) between the tetragonal and cubic structure is obtained at room temperature for the composition x=0.15. The doping of Ca facilitates the enhancement of the homogeneity of microstructure and growth of the grain size. The phase transition is also confirmed by Raman spectroscopy. In order to explore the effect of Ca concentration variation on the conduction mechanism of BaZr{sub 0.1}Ti{sub 0.9}O{sub 3} (BZT) ceramic, the frequency dependent ac impedance spectroscopy technique is used at various temperatures. The effect of Ca doping on the electrical properties of BZT is clearly noticeable. The resistance of the grain (bulk) and the grain boundary is increased as a consequence of the increase in the activation energy of Ca substituted BZT samples. The enhanced resistivity of the Ca substituted BZT ceramics is explained in terms of the decrease in the mobility of the charge carriers associated with the lattice distortion. The electric modulus analysis reveals the enhanced capacitance of BCZT ceramics which is in good agreement with the results obtained from complex impedance analysis.

  2. Raman scattering, microstructural and dielectric studies on Ba{sub 1-x}Ca{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sunil; Kundu, Swarup [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Ochoa, D.A.; Garcia, J.E. [Department of Applied Physics, Universitat Politecnica de Catalunya, 08034 Barcelona (Spain); Varma, K.B.R., E-mail: kbrvarma@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)

    2012-10-15

    Polycrystalline powders of Ba{sub 1-x}Ca{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} (where x = 0, 0.25, 0.50, 0.75 and 1) were prepared via the conventional solid-state reaction route. X-ray diffraction (XRD) and Raman scattering techniques have been employed to probe into the structural changes on changing x. XRD analyses confirmed the formation of monophasic bismuth layered structure of all the above compositions with an increase in orthorhombic distortion with increase in x. Raman spectra revealed a redshift in A{sub 1g} peak and an increase in the B{sub 2g}/B{sub 3g} splitting with increasing Ca content. The average grain size was found to increase with increasing x. The temperature of the maximum dielectric constant (T{sub m}) increased linearly with increasing Ca-content whereas the diffuseness of the phase transition was found to decrease with the end member CaBi{sub 4}Ti{sub 4}O{sub 15} showing a frequency independent sharp phase transition around 1048 K. Ca doping resulted in a decrease in the remnant polarization and an increase in the coercive field. Ba{sub 0.75}Ca{sub 0.25}Bi{sub 4}Ti{sub 4}O{sub 15} ceramics showed an enhanced piezoelectric coefficient d{sub 33} of 15 pC N{sup -1} at room temperature. Low values of dielectric losses and tunability of temperature coefficient of dielectric constant ({tau}{sub {epsilon}}) in the present solid-solution suggest that these compounds can be of potential use in microwave dielectrics at high temperatures. Highlights: Black-Right-Pointing-Pointer Ba{sub 1-x}Ca{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} (0 {<=} x {<=} 1) ceramics with four-layer Aurivillius structure were fabricated. Black-Right-Pointing-Pointer X-ray diffraction and Raman scattering techniques have been employed to probe into the structural changes on changing x. Black-Right-Pointing-Pointer Curie temperature (T{sub C}) was found to increase with increase in Ca-doping whereas the diffuseness of phase transition decreased. Black-Right-Pointing-Pointer Temperature

  3. PDMS-SiO{sub 2}-TiO{sub 2}-CaO hybrid materials – Cytocompatibility and nanoscale surface features

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, J. Carlos [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Wacha, András [Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja 2, Budapest 1117 (Hungary); Gomes, Pedro S.; Fernandes, M. Helena R. [Laboratory for Bone Metabolism and Regeneration, Faculdade de Medicina Dentária, Universidade do Porto (Portugal); Fernandes, M. Helena Vaz [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Salvado, Isabel M. Miranda, E-mail: isabelmsalvado@ua.pt [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal)

    2016-07-01

    Two PDMS-SiO{sub 2}-TiO{sub 2}-CaO porous hybrid materials were prepared using the same base composition, precursors, and solvents, but following two different sol-gel procedures, based on the authors' previous works where for the first time, in this hybrid system, calcium acetate was used as calcium source. The two different procedures resulted in monolithic materials with different structures, microstructures, and surface wettability. Even though both are highly hydrophobic (contact angles of 127.2° and 150.6°), and present different filling regimes due to different surface topographies, they have demonstrated to be cytocompatible when tested with human osteoblastic cells, against the accepted idea that high-hydrophobic surfaces are not suitable to cell adhesion and proliferation. At the nanoscale, the existence of hydrophilic silica domains containing calcium, where water molecules are physisorbed, is assumed to support this capability, as discussed. - Highlights: • Two hybrid materials were prepared following two different sol-gel procedures. • Both are highly hydrophobic but demonstrated to be cytocompatible. • Different filling regimes were observed.

  4. Dielectric properties of Nb-doped CaCu{sub 3}Ti{sub 4}O{sub 12} electroceramics measured at high frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, Muhammad Azwadi [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Hutagalung, Sabar D., E-mail: mrsabar@eng.usm.m [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Ain, Mohd Fadzil [School of Electrical and Electronic Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Ahmad, Zainal A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2010-03-18

    In this work, Nb dopant was introduced into CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) electroceramic in order to improve the dielectric properties. The CCTO electroceramic was prepared using the solid state reaction method. An X-ray diffractometer (XRD) analysis proved the formation of a single CCTO phase after sintering at 1040 {sup o}C for 10 h. Abnormal grain growth was observed in undoped CCTO and 1 mol% Nb-doped CCTO. Normal grain growth was produced at Nb dopant levels higher than 3 mol%. Dielectric properties were measured at a frequency range of 1 MHz to 1 GHz. It was found that CCTO doped with 1 mol% Nb gave the highest dielectric constant of 18,000 at 1 MHz. Meanwhile, the lowest dielectric loss (0.31) at 1 MHz was given by CCTO doped with 10 mol% Nb. The dielectric constant between 10 MHz and 1 GHz was almost stable with values at around 500.

  5. Microstructural and Dielectric Properties of Zr Doped Microwave Sintered CaCu3Ti4O12 Synthesized by Sol-Gel Route

    Directory of Open Access Journals (Sweden)

    S. Jesurani

    2014-01-01

    Full Text Available Polycrystalline samples with the chemical formula CaCu3Ti4-xZrxO12 (x=0, 0.02, 0.1, 0.2, 0.5, and 0.1 CCTZO were synthesized from metal nitrate solutions by the sol-gel method, followed by conventional and microwave heat treatments. The X-ray diffraction pattern of powder calcined at 800°C in conventional furnace for 3 h showed formation of a single phase. The crystal structure did not change on doping with zirconium and it remained cubic in the five studied compositions. The surface morphology of samples sintered at 1000°C in microwave furnace for 10 min was observed using a high resolution scanning electron microscope (HR-SEM. The grain sizes were in the range of 250 nm–5 μm for these samples. HRSEM results show that doping with Zr enhanced grain growth or densification. Energy dispersive X-ray spectroscopy (EDX confirmed the presence of Zr. The dielectric characteristics of Zr doped CCTO were studied with an LCR meter in the frequency range of 50 Hz–1 MHz. A very high dielectric constant 21,500 was observed for the sample doped with Zr (0.02 mol% at 50 Hz.

  6. Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-02-01

    Full Text Available Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx, their chemical reactions and bonding with polydimethylsiloxane (PDMS were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz was obtained for the ceramic sintered at 1050 °C (S1050 and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%, viscoelastic property (tanδ = E″/E′: 0.225 and glass transition temperature (Tg: −58.5 °C were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000% and its flexible S1050/PDMS composite film (306% based humidity sensors was found to be at 100 Hz, better than conventional materials.

  7. Multiferroic behavior on nanometric La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Prieto, Pedro; Ordoñez, John Edward; Gomez, Maria Elena; Lopera, Wilson

    2014-03-01

    We have deposited bilayers of the FM La2/3Ca1/3MnO3 and FE BaTiO3 as a route to design systems with artificial magnetoelectric coupling on LCMO/BTO/Nb:STO system. We maintain a fixed magnetic layer thickness (tLCMO = 48 nm) and varying the thickness of the ferroelectric layer (tBTO = 20, 50, 100 nm). We analyze the influence of the thickness ratio (tBTO/ tLCMO) in electrical and magnetic properties of manganite. From X-ray diffraction analysis we observed that the samples grew textured. Magnetization and transport measurements indicate a possible multiferroic behavior in the bilayer. We found an increase in the Curie and metal-insulator transition temperature in the bilayer in comparison with those for LCMO (48nm)/STO. Hysteresis loops on bilayers show ferromagnetic behavior. This work has been supported by the ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' Colciencias-CENM Research Projects: No. 1106-48-925531 and CI7917-CC 10510 contract 0002-2013 COLCIENCIAS-UNIVALLE.

  8. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption.

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-07-21

    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%-95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

  9. Novel magnetic–dielectric composite ceramic obtained from Y{sub 3}Fe{sub 5}O{sub 12} and CaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, D.V.M. [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil); Silva, M.A.S. [Laboratório de Telecomunicações e Ciência e Engenharia de Materiais (LOCEM), Departamento de Física, Universidade Federal do Ceará (Brazil); Ribeiro, T.S.; Vasconcelos, I.F. [Laboratório de Magnetismo e Materiais Magnéticos, Departamento de Engenharia Metalúrgica e de Materiais, UFC (Brazil); Sombra, A.S.B.; Góes, J.C. [Laboratório de Telecomunicações e Ciência e Engenharia de Materiais (LOCEM), Departamento de Física, Universidade Federal do Ceará (Brazil); Fechine, P.B.A., E-mail: fechine@ufc.br [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil)

    2015-09-25

    Highlights: • The density of composites was improved with addition of CTO. • Dielectric permittivity of the composites presented values above the expected. • The composites presented magnetic permeability higher than YIG after 500 MHz. - Abstract: This work investigates the microstructure and magnetic–dielectric properties of the CaTiO{sub 3} (CTO) and Y{sub 3}Fe{sub 5}O{sub 12} (YIG) composite ceramic. CTO is a paramagnetic ceramic, presents a positive value of Resonant Frequency Temperature Coefficients (τ{sub f}) and has high dielectric permittivity (ε{sub r}) while YIG is ferromagnetic, has low ε{sub r} and negative τ{sub f} values. Therefore, it is expected that the composite from these individual phase shows new properties, or a mix of them derived from each component. X-ray powder diffraction (XRPD), Scanning Electron Microscope (SEM), Raman and {sup 57}Fe Mössbauer spectroscopy were performed to confirm the phases of the composites. The dielectric and magnetic properties in Radio-Microwave frequencies were studied by impedance spectroscopy using different geometries. It was observed a densification improvement resulting from the insertion of the CTO in composites and a chemical reaction between YIG and CTO phases. This new composite has potential applications in bulk and thick/thin films devices.

  10. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors. PMID:27455263

  11. Piezoelectric and pyroelectric properties of Cu-doped CaBi{sub 4}Ti{sub 4}O{sub 15} lead-free ferroelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kwok, K W; Wong, H Y [Department of Applied Physics and Materials Research Centre, Hong Kong Polytechnic University, Kowloon (Hong Kong)

    2009-05-07

    Dense Cu-doped CaBi{sub 4}Ti{sub 4}O{sub 15} ferroelectric ceramics have been fabricated by a conventional ceramic technique. After doping by Cu, the ceramics become denser, and their electrical, piezoelectric and pyroelectric properties are improved. At the optimum doping level of 0.5 mol%, the ceramic exhibits a high density (6940 kg m{sup -3}), a low dielectric constant (145), a low dielectric loss (0.12%), a high resistivity (2.5 x 10{sup 13} {Omega} cm), a large piezoelectric coefficient (12.4 pC N{sup -1}) and a large pyroelectric coefficient (86 {mu}C K{sup -1} m{sup -2}). Unlike the piezoelectric properties, the pyroelectric properties, in particular those relating to the pyroelectric detection, of the ceramics are good and comparable to those of the lead-based ferroelectric ceramics. For the ceramic doped with 0.5 mol% Cu, the voltage and detectivity figures of merit for pyroelectric detection have large values of 2.6 x 10{sup -2} m{sup 2} C{sup -1} and 2.7 x 10{sup -5} Pa{sup -1/2}, respectively, indicating that it is a promising candidate for pyroelectric applications.

  12. Preparation of textured CaBi4Ti4O15 based ceramics and dielectric properties optimized with La3+ doping

    Directory of Open Access Journals (Sweden)

    ZHENG Qianqian

    2012-12-01

    Full Text Available A batch of 001>textured CaBi4Ti4O15(x=0,0.1,0.2,0.3,0.4 (CBLT-x ceramics were fabricated by a two-step sintering method:synthesizing seed-crystal platelets by molten-salt method with oxide mixture as precursor,and then sintering the platelets via grain orientation technique (OCAP.Microstructural characterization by SEM was performed to establish the effect of increased doping of La3+ and sintering temperature on grain growth and texture development.Increasing La3+(to x=0.4 resulted in dielectric constant improvement up to 570 sintered at 1150℃ in the direction perpendicular to the tapecasting plan.The dielectric constant as well as loss of CBLT-x samples in the perpendicular direction is higher than that of parallel plane.The mechanism controlling the texture and grain growth in CBLT-xceramics is firstly discussed by 3D patterns in this letter.

  13. Piezoelectric and pyroelectric properties of Cu-doped CaBi4Ti4O15 lead-free ferroelectric ceramics

    Science.gov (United States)

    Kwok, K. W.; Wong, H. Y.

    2009-05-01

    Dense Cu-doped CaBi4Ti4O15 ferroelectric ceramics have been fabricated by a conventional ceramic technique. After doping by Cu, the ceramics become denser, and their electrical, piezoelectric and pyroelectric properties are improved. At the optimum doping level of 0.5 mol%, the ceramic exhibits a high density (6940 kg m-3), a low dielectric constant (145), a low dielectric loss (0.12%), a high resistivity (2.5 × 1013 Ω cm), a large piezoelectric coefficient (12.4 pC N-1) and a large pyroelectric coefficient (86 µC K-1 m-2). Unlike the piezoelectric properties, the pyroelectric properties, in particular those relating to the pyroelectric detection, of the ceramics are good and comparable to those of the lead-based ferroelectric ceramics. For the ceramic doped with 0.5 mol% Cu, the voltage and detectivity figures of merit for pyroelectric detection have large values of 2.6 × 10-2 m2 C-1 and 2.7 × 10-5 Pa-1/2, respectively, indicating that it is a promising candidate for pyroelectric applications.

  14. Dielectric behavior of CaCu3Ti4O12: Poly Vinyl Chloride ceramic polymer composites at different temperature and frequencies

    Directory of Open Access Journals (Sweden)

    Ajay Pratap Singh

    2016-12-01

    Full Text Available In this study, the efforts have been made to obtain relatively high dielectric constant polymer-ceramic composite by incorporating the giant dielectric constant material, calcium copper titanate (CCTO in a PVC polymer matrix. We have prepared composites of CaCu3Ti4O12 (CCTO ceramic and Poly Vinyl Chloride (PVC polymer in various ratios (by volume in addition to pure CCTO. For this, CCTO was prepared by the conventional oxide route (solid-state reaction method. The structural, the microstructural and the dielectric properties of the composites were studied using X-ray diffraction, Scanning Electron Microscope, and impedance analyzer respectively. The study of dielectric constant and dielectric loss of the pure CCTO and the composites reveal that there is good range of dielectric constants and dielectric losses for the studied composites. The pure sample of CCTO exhibits giant dielectric constant at low frequency within the studied temperature range. As frequency increases, dielectric constant drastically decreases and approaching a constant value at 1 MHz. Above the intermediate temperature, the dielectric constant and dielectric loss for pure CCTO is more frequency dependent than its composites.

  15. Structural analysis, optical and dielectric function of [Ba0.9Ca0.1](Ti0.9Zr0.1)O3 nanocrystals

    Science.gov (United States)

    Herrera-Pérez, G.; Morales, D.; Paraguay-Delgado, F.; Borja-Urby, R.; Reyes-Rojas, A.; Fuentes-Cobas, L. E.

    2016-09-01

    This work presents the identification of inter-band transitions in the imaginary part of the dielectric function (ɛ2) derived from the Kramers-Kronig analysis for [Ba0.9Ca0.1](Ti0.9Zr0.1)O3 (BCZT) nanocrystals synthesized by the modified Pechini method. The analysis started with the chemical identification of the atoms that conform BCZT in the valence loss energy region of a high energy-resolution of electron energy loss spectroscopy. The indirect band energy (Eg) was determined in the dielectric response function. This result is in agreement with the UV-Vis technique, and it obtained an optical band gap of 3.16 eV. The surface and volume plasmon peaks were observed at 13.1 eV and 26.2 eV, respectively. The X-ray diffraction pattern and the Rietveld refinement data of powders heat treated at 700 °C for 1 h suggest a tetragonal structure with a space group (P4 mm) with the average crystal size of 35 nm. The average particle size was determined by transmission electron microscopy.

  16. Obtención de pigmentos cerámicos de perovskita CaTiO3 dopada con cromo y vanadio por descomposición metal-orgánica (MOD

    Directory of Open Access Journals (Sweden)

    Monrós, G.

    2012-12-01

    Full Text Available The Metal Organic Decomposition (MOD route based on the chelation of a solution of metallic salts (usually nitrates by policarboxylic acid (oxalic and citric, applied to the synthesis of ceramic pigments based on chromium and vanadium doped CaTiO3 perovskite, is presented in this paper. MOD synthesis allows preparing ceramic inks using the raw emulsioned materials directly or the nanostructured charried powders at 500ºC dispersed in DEG, and also stable ceramic pigments in glazes when the particle size and crystallization are sufficiently. In the CaTiO3 perovskite 20% molar modified with vanadium in the Ti position, ceramic inks using charried powders produce adequate orange shades and the fired powders at 1000ºC produce adequate orange colours in glazes. Samples of 1.5 molar addition of policarboxylic acids show the best pigmenting properties. In the case of CaTiO3 perovskite 1% molar modified with chromium in the Ti position, ceramic inks using charried powders produce adequate pink shades and the fired powders at 1000ºC produce adequate pink colours in glazes. Samples of 0.25 molar addition of policarboxylic acids show the best pigmenting properties.En el trabajo se presenta la utilización de una ruta de descomposición metal-orgánica MOD (Metal Organic Decomposition, basada en la formación de quelatos por adición de un ácido policarboxílico (oxálico y cítrico a una disolución de sales metálicas (usualmente nitratos, en la síntesis de pigmentos cerámicos de perovskita CaTiO3 dopada con cromo y vanadio. La síntesis MOD permite el desarrollo de tintas cerámicas tipo emulsión a partir de los materiales crudos, de tintas tipo dispersión con los materiales carbonizados nanoestructurados en DEG, así como pigmentos estables en vidriados cuando los tamaños de partícula presentan tamaños y grados de cristalización suficientes. En la perovskita de CaTiO3 modificada con un 20% de vanadio en la posición del Ti, las tintas con

  17. SC tuning fork

    CERN Multimedia

    The tuning fork used to modulate the radiofrequency system of the synchro cyclotron (SC) from 1957 to 1973. This piece is an unused spare part. The SC was the 1st accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990. In the SC the magnetic field did not change with time, and the particles were accelerated in successive pulses by a radiofrequency voltage of some 20kV which varied in frequency as they spiraled outwards towards the extraction radius. The frequency varied from 30MHz to about 17Mz in each pulse. The tuning fork vibrated at 55MHz in vacuum in an enclosure which formed a variable capacitor in the tuning circuit of the RF system, allowing the RF to vary over the appropriate range to accelerate protons from the centre of the macine up to 600Mev at extraction radius. In operation the tips of the tuning fork blade had an amplitude of movement of over 1 cm. The SC accelerator underwent extensive improvements from 1973 to 1975, including the installation of a...

  18. Ferroelectric domain structures of epitaxial CaBi2Nb2O9 thin films on single crystalline Nb doped (1 0 0) SrTiO3 substrates

    Science.gov (United States)

    Ahn, Yoonho; Seo, Jeong Dae; Son, Jong Yeog

    2015-07-01

    Epitaxial CaBi2Nb2O9 (CBNO) thin films were deposited on Nb-doped SrTiO3 substrates. The CBNO thin films as a lead-free ferroelectric material exhibit a good ferroelectric property with the remanent polarization of 10.6 μC/cm2. In the fatigue resistance test, the CBNO thin films have no degradation in polarization up to 1×1012 switching cycles, which is applicable for non-volatile ferroelectric random access memories (FeRAMs). Furthermore, piezoresponse force microscopy study (PFM) reveals that the CBNO thin films have larger ferroelectric domain structures than those of PbTiO3 thin films. From the Landau, Lifshiftz, and Kittel's scaling law, it is inferred that the domain wall energy of CBNO thin films is probably very similar to that of the PbTiO3 thin films.

  19. Laser sintering and dielectric characterization of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics; Sinterizacao a laser e caracterizacao dieletrica de ceramicas de CaCu{sub 3}Ti{sub 4}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, L.M.; Barbosa, L.B.; Silva, R.S. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Fisica. Grupo de Materiais Ceramicos Avancados

    2012-07-01

    Calcium and copper titanate (CaCu{sub 3}Ti{sub 4}O{sub 12} - CCTO) has been prepared by several researchers mainly through conventional ceramic processing. However, other synthesis methods have been tested in the last years. In this work, we have studied the CCTO synthesis by a route based on the Pechini method and its sintering using a new method, in which a CO{sub 2} laser is used as the main heating source. Besides, the dielectric properties of CCTO ceramics were investigated in order to verify the influence of this sintering process on the ceramic properties. The laser sintered ceramics presented high relative density (95 ± 1%), with homogeneous microstructure and single crystalline phase and dielectric constant changing from ∼ 1100 to 2100 (with dielectric loss of ∼ 0.05), when measured at 1 kHz and at room temperature. (author)

  20. Characterization and study of dielectric and electrical properties of CaBi4Ti4O{sub 15} (CBT) added with Bi{sub 2}O{sub 3}; Caracterizacao e estudo das propriedades eletricas e dieletricas do CaBi{sub 4}Ti{sub 4}O{sub 15} (CBT) adicionado com Bi{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, D.B.; Campos Filho, M.C.; Sales, J.C.; Silva, P.M.O.; Sombra, A.S. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil)

    2011-07-01

    The ceramic perovskite CaBi{sub 4}Ti{sub 4}O{sub 15} (CBT) of space group A21am, Aurivillius family with deficiency A{sub 5}B{sub 4}O{sub 15} cation has been prepared by solid state method in a planetary ball mill of high energy. The reagents samples were ground and calcined and then added with Bi{sub 2}O{sub 3} (2% wt.) This work aims to characterize by X-ray diffraction to study the electrical properties and dielectric properties of (CBT). The x-ray diffraction revealed the formation of single orthorhombic phase. As for the dielectric properties (dielectric constant and dielectric loss) were measured at 30 deg C to 450 deg C, through which can be verified the presence of thermally activated processes. This phase has properties very relevant for possible use in capacitive devices, miniaturized filters, dielectric resonators antennas and oscillators. (author)

  1. Thickness dependent microstructural changes in La{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films deposited on (111) SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Aydogdu, G.H., E-mail: G.Aydogdu@fkf.mpg.d [Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569, Stuttgart (Germany); Kuru, Y. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569, Stuttgart (Germany); Nelayah, J.; Aken, P.A. van [Max Planck Institute for Metals Research, Heisenbergstr. 3, D-70569, Stuttgart (Germany); Habermeier, H.-U. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569, Stuttgart (Germany)

    2010-06-01

    The epitaxial strain can modify the physical properties of complex oxide thin films considerably. The strain effect is expected to be less pronounced for relatively thick films and the physical properties should resemble to the bulk material. However, it has been recently observed that the electronic and magnetic properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films deposited on (111) SrTiO{sub 3} substrates thicker than a threshold value differ considerably from the bulk material. This observation is a hint for some interesting microstructural features in these films. In the present study, the microstructure of La{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films on (111) SrTiO{sub 3} substrates is investigated by X-ray diffraction and high resolution transmission electron microscopy.

  2. Cyclotron production of {sup 43}Sc for PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Walczak, Rafał [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Krajewski, Seweryn [Synektik S.A., Research and Development Center, Warsaw (Poland); Szkliniarz, Katarzyna [Department of Nuclear Physics, University of Silesia, Katowice (Poland); Sitarz, Mateusz [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Abbas, Kamel [Nuclear Security Unit, Joint Research Centre, Institute for Transuranium Elements, European Commission, Ispra (Italy); Choiński, Jarosław; Jakubowski, Andrzej; Jastrzębski, Jerzy [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Majkowska, Agnieszka [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Simonelli, Federica [Nuclear Decommissioning Unit, Joint Research Centre, Ispra Site Management Directorate, European Commission, Ispra (Italy); Stolarz, Anna; Trzcińska, Agnieszka [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Zipper, Wiktor [Department of Nuclear Physics, University of Silesia, Katowice (Poland); Bilewicz, Aleksander [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland)

    2015-12-04

    Recently, significant interest in {sup 44}Sc as a tracer for positron emission tomography (PET) imaging has been observed. Unfortunately, the co-emission by {sup 44}Sc of high-energy γ rays (E{sub γ} = 1157, 1499 keV) causes a dangerous increase of the radiation dose to the patients and clinical staff. However, it is possible to produce another radionuclide of scandium—{sup 43}Sc—having properties similar to {sup 44}Sc but is characterized by much lower energy of the concurrent gamma emissions. This work presents the production route of {sup 43}Sc by α irradiation of natural calcium, its separation and purification processes, and the labeling of [DOTA,Tyr3] octreotate (DOTATATE) bioconjugate. Natural CaCO{sub 3} and enriched [{sup 40}Ca]CaCO{sub 3} were irradiated with alpha particles for 1 h in an energy range of 14.8–30 MeV at a beam current of 0.5 or 0.25 μA. In order to find the optimum method for the separation of {sup 43}Sc from irradiated calcium targets, three processes previously developed for {sup 44}Sc were tested. Radiolabeling experiments were performed with DOTATATE radiobioconjugate, and the stability of the obtained {sup 43}Sc-DOTATATE was tested in human serum. Studies of {sup nat}CaCO{sub 3} target irradiation by alpha particles show that the optimum alpha particle energies are in the range of 24–27 MeV, giving 102 MBq/μA/h of {sup 43}Sc radioactivity which creates the opportunity to produce several GBq of {sup 43}Sc. The separation experiments performed indicate that, as with {sup 44}Sc, due to the simplicity of the operations and because of the chemical purity of the {sup 43}Sc obtained, the best separation process is when UTEVA resin is used. The DOTATATE conjugate was labeled by the obtained {sup 43}Sc with a yield >98 % at elevated temperature. Tens of GBq activities of {sup 43}Sc of high radionuclidic purity can be obtainable for clinical applications by irradiation of natural calcium with an alpha beam.

  3. 45Ti extraction using hydroxamate resin

    DEFF Research Database (Denmark)

    Gagnon, K.; Severin, Gregory; Barnhart, T. E.

    2012-01-01

    As an attractive radionuclide for positron emission tomography, this study explores the extraction and reactivity of 45Ti produced via the 45Sc(p,n)45Ti reaction on a GE PETtrace. Using a small hydroxamate column, we have demonstrated an overall recovery of >50% of 45Ti in ~1 mL of 1M oxalic acid...

  4. Obtención de pigmentos cerámicos de perovskita CaTiO3 dopada con cromo y vanadio por descomposición metal-orgánica (MOD)

    OpenAIRE

    Monrós, G.; García, A; Badenes, J.; Llusar, M.; Cerro, S.; Galindo, R.; Gargori, C.

    2012-01-01

    The Metal Organic Decomposition (MOD) route based on the chelation of a solution of metallic salts (usually nitrates) by policarboxylic acid (oxalic and citric), applied to the synthesis of ceramic pigments based on chromium and vanadium doped CaTiO3 perovskite, is presented in this paper. MOD synthesis allows preparing ceramic inks using the raw emulsioned materials directly or the nanostructured charried powders at 500ºC dispersed in DEG, and also stable ceramic pigments in glazes when the ...

  5. Luminescent characteristics of UV excited Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: Pr{sup 3+} reddish-orange phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R., E-mail: prb.mgu@gmail.com

    2016-02-15

    Pr{sup 3+} doped Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3} phosphors were synthesised by solid state reaction process. The structure, surface morphology and photoluminescence of the prepared phosphors were analysed using XRD, SEM and photoluminescence spectroscopy respectively. The XRD pattern confirmed orthorhombic perovskite structure of the Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor shows the samples can be effectively excited with UV light at 336 nm and exhibit a strong reddish-orange emission at 611 nm. Concentration dependence of emission intensity shows concentration quenching effect on increasing Pr{sup 3+} concentration after x = 0.1 because of dipole–dipole interaction. Using Blasse's formula, critical distance for energy transfer was calculated. The CIE co-ordinates, CCT, colour purity and luminescence decay of the prepared phosphors were also calculated. These results offer the prepared phosphor as a suitable candidate for various photonic applications. - Highlights: • Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from {sup 3}P{sub J} levels of Pr{sup 3+} were absent due to the presence of IVCT band. • Concentration quenching due to dipole–dipole interaction was observed. • For x = 0.1, sample shows a maximum emission intensity with 91.7% colour purity.

  6. Tunable magnetocaloric effect in Sr{sub 1-x}Ca{sub x}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugapriya, K.; Palanivel, Balan [Pondicherry Engineering College, Department of Physics, Puducherry (India); Radheep, D.M.; Murugan, Ramaswamy [Pondicherry University, Department of Physics, Puducherry (India)

    2017-07-15

    Sr{sub 1-x}Ca{sub x}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} (x = 0.25, 0.5 and 0.75) polycrystalline samples were synthesized by conventional solid-state reaction. Magnetic characterizations of Sr{sub 1-x}Ca{sub x}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} revealed signature of antiferromagnetic ordering at temperatures (T{sub N}) ∝ 19, 25 and 29.5 K for x = 0.25, x = 0.5 and for x = 0.75, respectively. Sr{sub 1-x}Ca{sub x}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} (x = 0.75) exhibits field-induced antiferromagnetic to ferromagnetic transition at ∝ 30 K with applied magnetic field of 4 and 5 T. Magnetocaloric change (ΔS{sub M}) increases from 3.5 to 19 J/kg K by increasing calcium concentration in the A-site. Those ΔS{sub M} values are relatively very high in these classes of antiferromagnetic perovskite systems and equal to the magnetisation values of the ferromagnetic perovskite manganites. This is the first report for the Sr{sub 1-x}Ca{sub x}Mn{sub 0.5}Ti{sub 0.5}O{sub 3} (x = 0.75) having large magnetic entropy changes induced by the low magnetic field. (orig.)

  7. Electronic and thermoelectric properties of nonmagnetic inverse Heusler semiconductors Sc2FeSi and Sc2FeGe

    Science.gov (United States)

    Li, Jie; Yang, Guang; Yang, Yanmin; Ma, Hongran; Zhang, Qiang; Zhang, Zhidong; Fang, Wei; Yin, Fuxing; Li, Jia

    2017-11-01

    The electronic and thermoelectric properties of two nonmagnetic Hg2CuTi-type or called inverse Heusler semiconductors Sc2FeSi and Sc2FeGe are predicted by using first principles calculations and Boltzmann transport theory. The band gaps of Sc2FeSi and Sc2FeGe are 0.54 eV and 0.60 eV, respectively. Their zero total magneticmoments both satisfy the Mt = Zt-18 while not the Mt = Zt-24 rule. The good thermoelectric properties are achieved under the condition of electron doping. At the room temperature 300 K, the peak value of Seebeck coefficient is -592.02 μVK-1 for Sc2FeSi, and -609.38 μVK-1 for Sc2FeGe by electron doping. The maximum power factor is 48.77(1014 μW cm-1 K-2 s-1) for Sc2FeSi and 47.11(1014 μW cm-1 K-2 s-1) for Sc2FeGe with electron doping concentration -2.29 × 1026 m-3 and -2.42 × 1026 m-3, respectively, which are close to the power factor of well-known thermoelectric material Bi2Te3, indicating their potential applying values for thermoelectric devices.

  8. Carbon nitride–TiO2 hybrid modified with hydrogenase for visible light driven hydrogen production† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc02017d Click here for additional data file.

    Science.gov (United States)

    Caputo, Christine A.; Wang, Lidong; Beranek, Radim

    2015-01-01

    A system consisting of a [NiFeSe]–hydrogenase (H2ase) grafted on the surface of a TiO2 nanoparticle modified with polyheptazine carbon nitride polymer, melon (CNx) is reported. This semi-biological assembly shows a turnover number (TON) of more than 5.8 × 105 mol H2 (mol H2ase)–1 after 72 h in a sacrificial electron donor solution at pH 6 during solar AM 1.5 G irradiation. An external quantum efficiency up to 4.8% for photon-to-hydrogen conversion was achieved under irradiation with monochromatic light. The CNx–TiO2–H2ase construct was also active under UV-free solar light irradiation (λ > 420 nm), where it showed a substantially higher activity than TiO2–H2ase and CNx–H2ase due, in part, to the formation of a CNx–TiO2 charge transfer complex and highly productive electron transfer to the H2ase. The CNx–TiO2–H2ase system sets a new benchmark for photocatalytic H2 production with a H2ase immobilised on a noble- and toxic-metal free light absorber in terms of visible light utilisation and stability. PMID:28757952

  9. Effects of A-Site (NaCe) Substitution with Na-Deficiency on Structures and Properties of CaBi4Ti4O15-Based High-Curie-Temperature Ceramics

    Science.gov (United States)

    Yan, Haixue; Li, Chengen; Zhou, Jiaguang; Zhu, Weimin; He, Lianxin; Song, Yuxin; Yu, Youhua

    2001-11-01

    Three kinds of bismuth-layer-structured ferroelectric (BLSF) ceramics, CaBi4Ti4O15 (CBT), Ca0.8(CeNa)0.1Bi4Ti4O15 (CNBT), and Na-deficient Ca0.8(Ce0.1Na0.05\\Box0.05)Bi4Ti4O15 [CN\\BoxBT] (where \\Box represents vacancies) were prepared by a conventional ceramic technique. X-ray powder diffraction showed that their crystal structures are a single phase of BLSF with m=4. Sintering characteristics of the three ceramics were also discussed. Scanning electron microscope (SEM) micrographs of CN\\BoxBT showed that the grain is platelike. The A-site (NaCe) substitution can improve the piezoelectric constant d33 and high-temperature resistivity with decreasing Curie temperature. The modification by A-site (NaCe) substitution with Na-deficiency is more pronounced than CNBT, which not only leads to a very high piezoelectric constant d33 and high-temperature resistivity but also increases the Curie temperature. The reason for the high Tc (Tc=866°C) of CN\\BoxBT is considered to be internal stress. As a result, Na-deficient CN\\BoxBT ceramic is found to be an excellent high-temperature piezoelectric material.

  10. Microstructure and enhanced dielectric properties of yttrium and zirconium co-doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zunping, E-mail: xzp16213@163.com [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Qiang, Hua [College of Electromechanical Engineering, Chongqing College of Humanities, Science and Technology, Chongqing 401524 (China); Chen, Yi; Chen, Zhiqian [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China)

    2017-04-15

    CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics doped with Y{sub 2}O{sub 3}, ZrO{sub 2}, and (Y{sub 2}O{sub 3}+ZrO{sub 2}) were prepared by the citrate-nitrate combustion derived powders in order to investigate the effect of dopants on the microstructure and electrical properties. The results showed that giant dielectric response was enhanced by co-doping of Y{sup 3+} and Zr{sup 4+} ions at the Ti site. Y{sub 2}O{sub 3} and ZrO{sub 2} additive can inhibit the grain growth. Compared with other samples, (Y{sub 2}O{sub 3}+ZrO{sub 2}) co-doped ceramics exhibit a dense and homogenous fine-grained microstructure. A much better temperature and frequency stability of dielectric properties were realized in these ceramics. The dielectric loss (tan δ) < 0.05 in the frequency range of 200 Hz–60 kHz at room temperature, and in the temperature range of 15–72 °C at 10 kHz was successfully accomplished in (Y{sub 2}O{sub 3}+ZrO{sub 2}) co-doped CCTO ceramics. Low tan δ ∼0.039 and high dielectric constant (ε{sub r} ∼10196) were observed at room temperature and 10 kHz for the above ceramic samples, and the characteristic frequency shifts to higher frequency with increasing measuring temperature. The present results indicate that (Y{sub 2}O{sub 3}+ZrO{sub 2}) co-doping may improve the dielectric properties and increase the grain boundary resistance of CCTO. - Highlights: • Y and Zr co-doped CCTO exhibits a dense and homogenous fine-grained microstructure. • Y and Zr co-doped CCTO performs a lower dielectric loss in wide-range of frequency. • Temperature and frequency stability of dielectric properties were greatly enhanced.

  11. Dielectric and magnetic properties of xCoFe{sub 2}O{sub 4}–(1 − x)[0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}] composites

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Jyoti [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Yadav, K.L., E-mail: klyadav35@yahoo.com [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Prakash, Satya [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2014-12-15

    Highlights: • Spinel–perovskite xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) composites have been synthesized by solid state reaction method. • Two anomalies in dielectric constant have been identified, and the composites show relaxor behaviour. • The magnetic properties of the composites improve with increasing concentration of CoFe{sub 2}O{sub 4}. • Enhanced magnetodielectric effect is found, and magnetoelectric coupling has been confirmed by Δϵ ∼ γM{sup 2} relation. • Optical band gap energy of these composites has been reported for the first time. - Abstract: xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) composites with x = 0.1, 0.2, 0.3 and 0.4 have been synthesized by solid state reaction method. X-ray diffraction analysis and field emission secondary electron microscopy have been used for structural and morphological analysis, respectively. The spinel CoFe{sub 2}O{sub 4} and perovskite 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} phase could be identified in the composites. Two anomalies in dielectric constant have been identified: first one is close to ferroelectric to paraelectric phase transition of 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} ceramic and the other lies near the magnetic transition temperature of CoFe{sub 2}O{sub 4}. There is an increase in magnetocapacitance and saturation magnetization of the composites at room temperature with increase in CoFe{sub 2}O{sub 4} content. The magnetoelectric coupling coefficient (γ) was approximated by Δϵ ∼ γM{sup 2} relation. The optical band gap energy of the composites decreases with increase in CoFe{sub 2}O{sub 4} content.

  12. DiSC

    DEFF Research Database (Denmark)

    Pedersen, Rasmus; Sloth, Christoffer; Bruun Andresen, Gorm

    2015-01-01

    This paper presents the MATLAB simulation framework, DiSC, for verifying voltage control approaches in power distribution systems. It consists of real consumption data, stochastic models of renewable resources, flexible assets, electrical grid, and models of the underlying communication channels....... The simulation framework makes it possible to validate control approaches, and thus advance realistic and robust control algorithms for distribution system voltage control. Two examples demonstrate the potential voltage issues from penetration of renewables in the distribution grid, along with simple control...

  13. Out-of-plane and In-plane piezoelectric behaviors of [Ba(Zr0.2Ti0.8O3]–0.5(Ba0.7Ca0.3TiO3 thin films

    Directory of Open Access Journals (Sweden)

    Zhi Tao

    2017-12-01

    Full Text Available The piezoelectric properties of [Ba(Zr0.2Ti0.8O3]–0.5(Ba0.7Ca0.3TiO3 (abbreviated as BZT-0.5BCT thin films deposited on Pt/Ti/SiO2/Si substrates are reported in the present investigation. The effect of the distances between the target and substrate (d on the morphology and out-of-plane piezoelectric properties was investigated. The experimental results showed that the ferroelectric domains size was dependent on the distance between the substrate and target and the ferroelectric domain growth was constrained by the grains. The samples exhibited well-defined out-of-plane butterfly loops and hysteresis loops and the one with d of 6.5 cm possessed the optimal ferroelectric properties and it exhibited good in-plane piezoelectric properties.

  14. Non-isothermal crystallization kinetics of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin, E-mail: stra-ceo@163.com; Wang, Yongya; Luo, Wenqin; Li, Jingfen [Huzhou University, Department of Material Chemistry (China); Li, Jianyou [Huzhou Central Hospital, Orthopedic Department (China)

    2017-03-15

    Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass ceramics containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} were prepared by sol-gel method. The samples were characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The activation energy and kinetic parameters for crystallization of the samples were calculated by the Johnson-Mehi-Avrami (JMA) model and Augis-Bennett method according to the results of DSC. The results showed that the crystallization mechanism of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, whose non-isothermal kinetic parameter n = 2.3, was consistent with surface crystallization of the JMA model. The kinetics model function of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, f(α) = 2.3(1–α)[–ln(1–α)]{sup 0.57}, was also obtained. The addition of nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} could reduce the activation energy, which made the crystal growth modes change from onedimensional to three-dimensional.

  15. Effect of porosity on the ferroelectric and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 piezoelectric ceramics

    DEFF Research Database (Denmark)

    Yap, Emily W.; Glaum, Julia; Oddershede, Jette

    2018-01-01

    The ferroelectric and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) ceramics were measured as a function of porosity. Porous BCZT ceramics were fabricated using the sacrificial fugitive technique. Two different pore morphologies were induced by adding polymeric microspheres...... and fibres as the pore-forming agents. Increasing porosity led to decreasing ferroelectric and piezoelectric properties due to a reduction of polarisable BCZT ceramic available. With the benefit of being a lead-free piezoelectric material, porous BCZT ceramics may be considered for acoustic impedance...

  16. Preparation and characterization of (Ba,Cs)(M,Ti) 8O 16 (M = Al 3+, Fe 3+, Ga 3+, Cr 3+, Sc 3+, Mg 2+) hollandite ceramics developed for radioactive cesium immobilization

    Science.gov (United States)

    Aubin-Chevaldonnet, V.; Caurant, D.; Dannoux, A.; Gourier, D.; Charpentier, T.; Mazerolles, L.; Advocat, T.

    2007-06-01

    Among the different matrices proposed for selective and durable immobilization of radioactive cesium, (Ba x,Cs y)(M,Ti) 8O 16 hollandite ceramics, with x + y risks of Cs vaporization during synthesis, calcined powders were sintered in air at moderate temperature (1200 °C). This oxide route appeared as an alternative to the alkoxide route generally proposed to prepare hollandite waste form. For y = 0, single phase Ba x(M,Ti) 8O 16 was obtained only for M 3+ = Al 3+, Cr 3+ and Fe 3+. For y ≠ 0 and Fe 3+, all cesium was incorporated in hollandite and ceramic was well densified. For Cr 3+ and Ga 3+, only 46% and 63%, respectively, of Cs were retained in hollandite phase. For these samples, a high fraction of Cs was either evaporated and/or concentrated in a Cs-rich parasitic phase. Mixed hollandite samples with M 3+ = Ga 3+ + Al 3+ and M 3+ = Fe 3+ + Al 3+ were also synthesized and the best results regarding Cs immobilization and ceramic density were obtained with iron + aluminum but the sample porosity was higher than that of the sample containing only iron. All results were discussed by considering cations size and refractory character of oxides and hollandite ceramics.

  17. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  18. EIS, Mott Schottky and EFM analysis of the electrochemical stability and dielectric properties of Ca-P-Ag and Ca-P-Si-Ag coatings obtained by plasma electrolytic oxidation in Ti6Al4V

    OpenAIRE

    Sara María Leal-Marin; Hugo Armando Estupiñán-Duran

    2017-01-01

    El Ti6Al4V ELI (ASTM F136) es una de las aleaciones más empleadas en dispositivos de osteosíntesis y reemplazo articular. Sin embargo, las propiedades de esta aleación pueden ser mejoradas respecto a su biocompatibilidad y osteointegración con el tejido óseo a través de recubrimientos. El objetivo de este trabajo fue evaluar el comportamiento electroquímico de un recubrimiento obtenido por oxidación por plasma electrolítico sobre Ti6Al4V ELI empleando soluciones electrolíticas enriquecidas co...

  19. Effect of the Cr2O3 and TiO2 as nucleating agents in SiO2-Al2O3-CaO-MgO glass-ceramic system

    Science.gov (United States)

    Back, Gu-Seul; Yoon, Mi-Jung; Jung, Woo-Gwang

    2017-07-01

    The nucleation agent is one of the most important factors in glass-ceramics as it can control either the crystallization temperature or the activation energy. In this study, we investigated the effect of two common nucleation agents, TiO2 and Cr2O3, in the SiO2-Al2O3-CaO-MgO system. To determine the effect of TiO2 and Cr2O3 on nucleation, we measured the crystallization temperature by differential scanning calorimetry (DSC) scanning. To determine the activation energy of nucleation, the DSC scanning was made for the selected samples at various speeds. Also, the crystallinity of the selected sample was evaluated from the scattering intensity in X-ray diffractometry. Using DSC scanning, we found that TiO2 was effective in decreasing the crystallization temperature, while Cr2O3 was effective in decreasing the activation energy. We also performed nucleation heat treatment near the glass transition point. It is found that nucleation heat treatment was not effective in decreasing the crystallization temperature in our experimental condition. The XRD scattering method results showed that temperature is the key factor in crystallization and the effect of time is not as important.

  20. 45Sc Solid State NMR studies of the silicides Sc TSi ( T=Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt)

    Science.gov (United States)

    Harmening, Thomas; Eckert, Hellmut; Fehse, Constanze M.; Sebastian, C. Peter; Pöttgen, Rainer

    2011-12-01

    The silicides Sc TSi ( T=Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) were synthesized by arc-melting and characterized by X-ray powder diffraction. The structures of ScCoSi, ScRuSi, ScPdSi, and ScIrSi were refined from single crystal diffractometer data. These silicides crystallize with the TiNiSi type, space group Pnma. No systematic influences of the 45Sc isotropic magnetic shift and nuclear electric quadrupolar coupling parameters on various structural distortion parameters calculated from the crystal structure data can be detected. 45Sc MAS-NMR data suggest systematic trends in the local electronic structure probed by the scandium atoms: both the electric field gradients and the isotropic magnetic shifts relative to a 0.2 M aqueous Sc(NO 3) 3 solution decrease with increasing valence electron concentration and within each T group the isotropic magnetic shift decreases monotonically with increasing atomic number. The 45Sc nuclear electric quadrupolar coupling constants are generally well reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code.

  1. High Permittivity (1 - x)Ba(Zr(0.2)Ti(0.8))O3 - x(Ba(0.7)Ca(0.3))TiO3 (x = 0.45) Epitaxial Thin Films with Nanoscale Phase Fluctuations.

    Science.gov (United States)

    Scarisoreanu, Nicu D; Craciun, Floriana; Moldovan, Antoniu; Ion, Valentin; Birjega, Ruxandra; Ghica, Corneliu; Negrea, Raluca F; Dinescu, Maria

    2015-11-04

    Epitaxial (1 - x)Ba(Ti0.8Zr0.2)TiO3 - x(Ba0.7Ca0.3)TiO3, x = 0.45 (BCZT 45), thin films have been deposited on (001) SrTiO3 (STO) and (001/100) SrLaAlO4 (SLAO) substrates by pulsed laser deposition. X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) confirmed the epitaxial growth of the films. A high structural quality has been evidenced for the BCZT/STO films. Geometric phase analysis (GPA) associated with the HRTEM enabled us to obtain microstrain analysis and the in-plane and out-of-plane lattice parameter variation on different areas. Tetragonality ratio fluctuations at nanoscale level which are relevant for the existence of nanodomains have been evidenced on the BCZT/STO films. The in-plane dielectric constant has been measured on interdigital electrodes deposited by lift-off technique on the top of the films. High values of dielectric permittivity (>3000) combined with low dielectric loss (permittivity of BCZT thin films was attributed to their high structural quality and to the loss of rotation stability of the polarization associated with the presence of nanodomains. This results into a divergence of fluctuations of polarization direction and a peak of dielectric susceptibility. The enhanced switching of such nanodomain configuration was probed by piezoforce microscopy, by writing and reading domains during topography scanning.

  2. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

    Directory of Open Access Journals (Sweden)

    Ryszard Uklejewski

    2016-06-01

    Full Text Available We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold interfacing the components of resurfacing arthroplasty (RA endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the

  3. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses-Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation.

    Science.gov (United States)

    Uklejewski, Ryszard; Rogala, Piotr; Winiecki, Mariusz; Tokłowicz, Renata; Ruszkowski, Piotr; Wołuń-Cholewa, Maria

    2016-06-29

    We present here-designed, manufactured, and tested by our research team-the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the

  4. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

    Science.gov (United States)

    Uklejewski, Ryszard; Rogala, Piotr; Winiecki, Mariusz; Tokłowicz, Renata; Ruszkowski, Piotr; Wołuń-Cholewa, Maria

    2016-01-01

    We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the

  5. Magnetic dipole moment of the doubly closed-shell plus one proton nucleus $^{49}$Sc

    CERN Multimedia

    Gaulard, C V; Walters, W; Nishimura, K; Muto, S; Bingham, C R

    It is proposed to measure the magnetic moment of $^{49}$Sc by the Nuclear Magnetic Resonance on Oriented Nuclei (NMR-ON) method using the NICOLE on-line nuclear orientation facility. $^{49}$Sc is the neutron rich, doubly closed-shell, nucleus $^{48}$Ca plus one proton. Results will be used to deduce the effective g-factors in the $^{48}$Ca region with reference to nuclear structure and meson exchange current effects.

  6. Effect of doping of trivalent cations Ga{sup 3+}, Sc{sup 3+}, Y{sup 3+} in Li{sub 1.3}Al{sub 0.3}Ti{sub 1.7} (PO{sub 4}){sub 3} (LATP) system on Li{sup +} ion conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Kothari, Dharmesh H.; Kanchan, D.K., E-mail: dkkanchan.ssi@gmail.com

    2016-11-15

    We report the effect of trivalent cations dopants in the Li{sub 1.3}Al{sub 0.3−x}R{sub x}Ti{sub 1.7}(PO{sub 4}){sub 3} (R=Ga{sup 3+}, Sc{sup 3+}, Y{sup 3+}) NASICON ceramic system in the concentration range x=0.01,0.03,0.05,0.07, on the Li{sup +} ion conducting properties using impedance spectroscopy. The samples were prepared by solid state reaction method and characterized by X-Ray Diffraction and density measurements. The electrical properties were studied using impedance spectroscopy in frequency range 10 Hz to 20 MHz and temperature range 303 K to 423 K. Although the porosity of the material decreased with doping, the overall Li{sup +} ion conductivity of the system did not improve with doping. Ionic radii of the dopant cations was found to be an important factor in formation of impurity phases and low Li{sup +} ion conductivity. Gallium doped samples exhibited a higher Li{sup +} ion conductivity compared to its scandium and yttrium doped counterparts.

  7. Distribution Ratios of Phosphorus Between CaO-FeO-SiO2-Al2O3/Na2O/TiO2 Slags and Carbon-Saturated Iron

    Science.gov (United States)

    Li, Fengshan; Li, Xianpeng; Yang, Shufeng; Zhang, Yanling

    2017-10-01

    In order to effectively enhance the efficiency of dephosphorization, the distribution ratios of phosphorus between CaO-FeO-SiO2-Al2O3/Na2O/TiO2 slags and carbon-saturated iron ( LP^{Fe-C} ) were examined through laboratory experiments in this study, along with the effects of different influencing factors such as the temperature and concentrations of the various slag components. Thermodynamic simulations showed that, with the addition of Na2O and Al2O3, the liquid areas of the CaO-FeO-SiO2 slag are enlarged significantly, with Al2O3 and Na2O acting as fluxes when added to the slag in the appropriate concentrations. The experimental data suggested that LP^{Fe-C} increases with an increase in the binary basicity of the slag, with the basicity having a greater effect than the temperature and FeO content; LP^{Fe-C} increases with an increase in the Na2O content and decrease in the Al2O3 content. In contrast to the case for the dephosphorization of molten steel, for the hot-metal dephosphorization process investigated in this study, the FeO content of the slag had a smaller effect on LP^{Fe-C} than did the other factors such as the temperature and slag basicity. Based on the experimental data, by using regression analysis, log LP^{Fe-C} could be expressed as a function of the temperature and the slag component concentrations as follows: log LP^{Fe-C} = 0.059({pct}{CaO}) + 1.583log ({TFe}) - 0.052( {{pct}{SiO}2 } ) - 0.014( {{pct}{Al}2 {O}3 } ) \\quad + 0.142( {{pct}{Na}2 {O}} ) - 0.003( {{pct}{TiO}2 } ) + 0.049( {{pct}{P}2 {O}5 } ) + 13{,}527/T - 9.87.

  8. Monitor of SC beam profiles

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    A high-resolution secondary emission grid for the measurement of SC beam profiles. Modern techniques of metal-ceramic bonding, developed for micro-electronics, have been used in its construction. (See Annual Report 1977 p. 105 Fig. 12.)

  9. First coil for the SC

    CERN Multimedia

    CERN PhotoLab

    1955-01-01

    The coils for the SC magnet were stored in the large hangar of the Cointrin Airport (to make sure that they would be available before snow and ice would block the roads and canals from Belgium, where they were built).

  10. The Influence of Biomimetic Deposition Ca-P Coatings on the Release of Simvastatin from TiO2 Nanotube Array

    Directory of Open Access Journals (Sweden)

    Xie Chunlin

    2016-01-01

    Full Text Available In order to improve the capacity of simvastatin and extend the time of the release of the drug, this experiment adopts bionic-deposition to decorate a layer of octacalcium phosphate (OCP on the face of TiO2 nanotube array,and respectively discusses what are the appropriate parameters of octacalcium phosphate (OCP can be generated. Experiments show that loading a layer of octacalcium phosphate can extend the time of the release of the drug. In addition, the presence of simvastatin on the TiO2 nanotube array will be a certain influence on the morphology of octacalcium phosphate. However, simvastatin can be dissolved into the bionic fluid by using bionic deposition. Therefore, by step concentration soaking and then using this method to load OCP with simvastatin can effectively improve the amount of simvastatin loaded and extend drug release

  11. Magneto-transport properties of La 0.7 Ca 0.3 MnO 3/SrTiO 3/La 0.7 ...

    Indian Academy of Sciences (India)

    La0.7Ce0.3MnO3/SrTiO3/La0.7Ce0.3MnO3 tunnel junction; magneto-transport properties; magnetoresistance. ... University of Birmingham, B15 2TT, UK; Institut fur Festkorper und Wekstofforschung, Dresden, D-01069 Dresden, Germany; Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India ...

  12. Correlative characterization of primary Al{sub 3}(Sc,Zr) phase in an Al–Zn–Mg based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.H., E-mail: jie-hua.li@hotmail.com [Institute of Casting Research, Montanuniversität Leoben, A-8700 Leoben (Austria); Wiessner, M. [Materials Center Leoben Forschung GmbH, A-8700 Leoben (Austria); Albu, M. [Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Center for Electron Microscopy (Austria); Wurster, S. [Department of Materials Physics, Montanuniversität Leoben, Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, A-8700 Leoben (Austria); Sartory, B. [Materials Center Leoben Forschung GmbH, A-8700 Leoben (Austria); Hofer, F. [Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Center for Electron Microscopy (Austria); Schumacher, P. [Institute of Casting Research, Montanuniversität Leoben, A-8700 Leoben (Austria); Austrian Foundry Research Institute, A-8700 Leoben (Austria)

    2015-04-15

    Three-dimensional electron backscatter diffraction, focused ion beam, transmission electron microscopy and energy filtered transmission electron microscopy were employed to investigate the structural information of primary Al{sub 3}(Sc,Zr) phase, i.e. size, shape, element distribution and orientation relationship with the α-Al matrix. It was found that (i) most primary Al{sub 3}(Sc,Zr) phases have a cubic three-dimensional morphology, with a size of about 6–10 μm, (ii) most primary Al{sub 3}(Sc,Zr) phases are located within the α-Al matrix, and exhibit a cube to cube orientation relationship with the α-Al matrix, and (iii) a layer by layer growth was observed within primary Al{sub 3}(Sc,Zr) phases. Al, Cu, Si and Fe are enriched in the α-Al matrix between the layers of cellular eutectic Al{sub 3}(Sc,Zr) phase, while Sc, Ti and Zr are enriched in small Al{sub 3}(Sc,Zr) phases. A peritectic reaction and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed to interpret the observed layer by layer growth. This paper demonstrates that the presence of impurities (Fe, Si, Cu, Ti) in the diffusion field surrounding the growing Al{sub 3}(Sc,Zr) particle enhances the heterogeneous nucleation of Al{sub 3}(Sc,Zr) phases. - Highlights: • Most fine cubic primary Al{sub 3}(Sc,Zr) phases were observed within the α-Al matrix. • A layer by layer growth within primary Al{sub 3}(Sc,Zr) phase was observed. • A peritectic and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed. • Impurities in diffusion fields enhance heterogeneous nucleation of Al{sub 3}(Sc,Zr)

  13. Synthesis and Para-conductivity of (Tl $_{1-x} 1 - x Ti _{x} x )Ba _{2} 2 Ca _{2} 2 Cu _{3} 3 O _mathrm{y} y (x =$ = 0, 0.2, 0.4, 0.6, 0.8) Superconductors

    Science.gov (United States)

    Khan, Nawazish A.; Abbas, S. Qamar; Mahmood, Asif

    2016-01-01

    We have synthesized Ti-doped (Tl_{1-x}Tix)Ba2Ca2Cu3Oy ( x = 0, 0.2, 0.4, 0.6, 0.8) superconductors at normal pressure. The samples have shown T_c onset at 117, 118, 113, 110, and 115 K and the T_c (R=0) at 103, 96, 94, 97, and 106 K and the onset of diamagnetism around 109, 100, 98, 111, 100 K, respectively. The apical oxygen-related phonon modes are observed around 485 and 540 cm^{-1 }, and the planar oxygen modes at 600 cm^{-1}. These phonon modes are softened with the increase concentration of Ti in the final compound showing that Ti is incorporated into the (Tl_{1-x}Tix)Ba2Ca2Cu3Oy ( x = 0, 0.2, 0.4, 0.6, 0.8) samples. The excess conductivity analysis of these samples has shown an enhancement in the values of the parameters such as ξ _{c(0)}, J, and V_F with the doping of Ti. We proposed that the doping of Ti in the ( {Tl_{1-{x}} Ti_{{x}} })Ba_2 O_{4-δ } charge reservoir layer facilitates the charge transfer mechanism for conducting CuO2 planes which in turn enhance the values of aforementioned superconductivity parameters. The values of superconductivity parameters such as B_c(0), B_c1(0), B_c2(0), and J_c(0) are, however, suppressed with Ti doping. We suggested this to be arising from the weakening of flux pinning character in the final compound. These results have shown that the oxygen defect density in (Tl_{1-x}Tix)Ba2Ca2Cu3Oy samples is significantly suppressed with Ti doping.

  14. Observation of indium ion migration-induced resistive switching in Al/Mg{sub 0.5}Ca{sub 0.5}TiO{sub 3}/ITO

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zong-Han; Wang, Yeong-Her, E-mail: yhw@ee.ncku.edu.tw [Institute of Microelectronics, Department of Electrical Engineering, National Cheng-Kung University, Tainan, 701 Taiwan (China)

    2016-08-01

    Understanding switching mechanisms is very important for resistive random access memory (RRAM) applications. This letter reports an investigation of Al/Mg{sub 0.5}Ca{sub 0.5}TiO{sub 3} (MCTO)/ITO RRAM, which exhibits bipolar resistive switching behavior. The filaments that connect Al electrodes with indium tin oxide electrodes across the MCTO layer at a low-resistance state are identified. The filaments composed of In{sub 2}O{sub 3} crystals are observed through energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, nanobeam diffraction, and comparisons of Joint Committee on Powder Diffraction Standards (JCPDS) cards. Finally, a switching mechanism resulting from an electrical field induced by In{sup 3+} ion migration is proposed. In{sup 3+} ion migration forms/ruptures the conductive filaments and sets/resets the RRAM device.

  15. Large Electrocaloric Effect in Lead-Free (Ba0.85Ca0.15(Zr0.1Ti0.9O3 Ceramics Prepared via Citrate Route

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2017-09-01

    Full Text Available The 1 wt % Li-doped (Ba0.85Ca0.15(Zr0.1Ti0.9O3 (BCZT-Li ceramics prepared by the citrate method exhibit improved phase purity, densification and electrical properties, which provide prospective possibility to develop high-performance electrocaloric materials. The electrocaloric effect was evaluated by phenomenological method, and the BCZT-Li ceramics present large electrocaloric temperature change ∆T, especially large electrocaloric responsibility ξ = ∆Tmax/∆Emax, which can be comparable to the largest values reported in the lead-free piezoelectric ceramics. The excellent electrocaloric effect is considered as correlating with the coexistence of polymorphic ferroelectric phases, which are detected by the Raman spectroscopy. The large ξ value accompanied by decreased Curie temperature (around 73 °C of the BCZT-Li ceramics prepared by the citrate method presents potential applications as the next-generation solid-state cooling devices.

  16. A-site substitution effect of strontium on bismuth layered CaBi{sub 4}Ti{sub 4}O{sub 15} ceramics on electrical and piezoelectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Tanwar, Amit, E-mail: amit07tanwar@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Verma, Maya; Gupta, Vinay; Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2011-10-17

    Strontium substituted CaBi{sub 4}Ti{sub 4}O{sub 15} ceramics with the chemical formula Ca{sub 1-x}Sr{sub x}Bi{sub 4}Ti{sub 4}O{sub 15} (CSBT) (x = 0.0-1.0) have been prepared through conventional solid state route. The formation of single phase material with orthorhombic structure was verified from X-ray diffraction with incorporation of Sr substitution. Decrease in a-axis displacement of Bi ion in the perovskite structure in the CSBT ceramics were observed from the relative changes in soft mode (20 cm{sup -1}) in the Raman spectra, and increase in Sr incorporation shows the shift in ferroelectric to paraelectric phase transition temperature. The dielectric properties for all the CSBT ceramic compositions are studied as a function of temperature over the frequency range of 100 Hz-1 MHz. Curie's temperature was found to be function of Sr substitution and with increase in the Sr concentration the phase transition becomes sharper and phase transition temperature gets shifted towards lower temperature (790-545 deg. C). The behavior of ac conductivity as a function of frequency (100 Hz-1 MHz) at low temperature (<500 deg. C) follows the power law and attributed to hopping conduction mechanism. Sr substitution results in the increase in piezoelectric coefficients (d{sub 33}) whereas piezoelectric charge coefficient values were found comparable to that of PZT at room temperature. Relative changes in soft modes due to Sr incorporation results in high piezoelectricity in the CSBT ceramics.

  17. Sol-gel synthesis of quaternary (P2O5)55-(CaO)25-(Na2O)(20-x)-(TiO2) x bioresorbable glasses for bone tissue engineering applications (x = 0, 5, 10, or 15).

    Science.gov (United States)

    Foroutan, Farzad; Walters, Nick J; Owens, Gareth J; Mordan, Nicola J; Kim, Hae-Won; de Leeuw, Nora H; Knowles, Jonathan C

    2015-08-26

    In the present study, we report a new and facile sol-gel synthesis of phosphate-based glasses with the general formula of (P2O5)55-(CaO)25-(Na2O)(20-x)-(TiO2) x , where x = 0, 5, 10 or 15, for bone tissue engineering applications. The sol-gel synthesis method allows greater control over glass morphology at relatively low processing temperature (200 °C) in comparison with phosphate-based melt-derived glasses (~1000 °C). The glasses were analyzed using several characterization techniques, including x-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance ((31)P MAS-NMR), Fourier transform infrared (FTIR) spectroscopy and energy-dispersive x-ray (EDX) spectroscopy, which confirmed the amorphous and glassy nature of the prepared samples. Degradation was assessed by measuring the ion release and pH change of the storage medium. Cytocompatibility was also confirmed by culturing osteoblast-like osteosarcoma cell line MG-63 on the glass microparticles over a seven-day period. Cell attachment to the particles was imaged using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results revealed the potential of phosphate-based sol-gel derived glasses containing 5 or 10 mol% TiO2, with high surface area, ideal dissolution rate for cell attachment and easily metabolized dissolution products, for bone tissue engineering applications.

  18. Interface-enhanced sensitivity of photoconductivity to the electric current and magnetic field in La0.67Ca0.33MnO3/Nb-SrTiO3 p-n junctions

    Science.gov (United States)

    Wang, S.; Ma, Z. Z.; Xiong, J. J.; Li, C. J.; Hou, Y. H.; Ma, T. X.; Xiong, C. M.; Dou, R. F.; Nie, J. C.

    2016-12-01

    The effects of electric current and magnetic field on the photoconductivity (PC) of La0.67Ca0.33MnO3 (LCMO) films have been investigated within a comparative study on LCMO films on an n-type semiconducting Nb-doped SrTiO3 (NSTO) and insulating SrTiO3 (STO) substrates separately. At room temperature, LCMO on NSTO (LCMO/NSTO) was found to show remarkable PC effect than that on STO (LCMO/STO). More attractive is that, compared with that of LCMO/STO, the room-temperature PC of LCMO/NSTO also shows a high sensitivity to the change of current or magnetic field: for LCMO/NSTO under a light illumination with an intensity of 60 mW/cm2, the increment of current yields a decreases of PC at a rate of 7.6%/μA, while an application of magnetic field of 1.2 T can suppress PC by a percentage as high as ˜20%. In contrast, under the same stimulus of current or field, PC of LCMO/STO remains almost unchanged. The phenomena can be explained based on the interface effects correlated with the photocarrier injection, current shunting, and magnetic tunability occurred at the interface. This work demonstrates that manganite-based heterojunctions with interface engineering are promising for developing a new type of photoelectric device with high sensitivity and multifunctionality.

  19. Sc-45 nuclear magnetic resonance analysis of precipitation in dilute Al-Sc alloys

    NARCIS (Netherlands)

    Celotto, S; Bastow, TJ

    Nuclear magnetic resonance (NMR) with Sc-45 is used to determine the solid solubility of scandium in aluminium and to follow the precipitation of Al3Sc during the ageing of an Al-0.06 at.% Sc alloy via the two fully resolved peaks, corresponding to Sc in the solid solution Al matrix and to Sc in the

  20. Mixture designs to assess composition-structure-property relationships in SiO₂-CaO-ZnO-La₂O₃-TiO₂-MgO-SrO-Na₂O glasses: potential materials for embolization.

    Science.gov (United States)

    Kehoe, Sharon; Langman, Maxine; Werner-Zwanziger, Ulli; Abraham, Robert J; Boyd, Daniel

    2013-09-01

    Embolization with micron-sized particulates is widely applied to treat uterine fibroids. The objective of this work was to develop mixture designs to predict materials composition-structure-property relationships for the SiO₂-CaO-ZnO-La₂O₃-TiO₂-MgO-SrO-Na₂O glass system and compare its fundamental materials properties (density and cytocompatibility), against a state-of-the-art embolic agent (contour polyvinyl alcohol) to assess the potential of these materials for embolization therapies. The glass structures were evaluated using ²⁹Si MAS NMR to identify chemical shift and line width; the particulate densities were determined using helium pycnometry and the cell viabilities were assessed via MTT assay. ²⁹Si MAS NMR results indicated peak maxima for each glass in the range of -82.3 ppm to -89.9 ppm; associated with Q² to Q³ units in silicate glasses. All experimental embolic compositions showed enhanced in vitro compatibility in comparison to Contour PVA with the exceptions of ORP9 and ORP11 (containing no TiO₂). In this study, optimal compositions for cell viability were obtained for the following compositional ranges: 0.095-0.188 mole fraction ZnO; 0.068-0.159 mole fraction La₂O₃; 0.545-0.562 mole fraction SiO₂ and 0.042-0.050 mole fraction TiO₂. To ensure ease of producibility in obtaining good melts, a maximum loading of 0.068 mole fraction La₂O₃ is required. This is confirmed by the desirability approach, for which the only experimental composition (ORP5) of the materials evaluated was presented as an optimum composition; combining high cell viability with ease of production (0.188 mole fraction ZnO; 0.068 mole fraction La₂O₃; 0.562 mole fraction SiO₂ and 0.042 mole fraction TiO₂).

  1. Effect of surface chemistries and characteristics of Ti6Al4V on the Ca and P adsorption and ion dissolution in Hank's ethylene diamine tetra-acetic acid solution.

    Science.gov (United States)

    Chang, E; Lee, T M

    2002-07-01

    This study examined the influence of chemistries and surface characteristics of Ti6Al4V on the adsorption of Ca and P species and ion dissolution behavior of the material exposed in Hank's solution with 8.0 mM ethylene diamine tetra-acetic acid at 37 degrees C. The variation of chemistries of the alloy and nano-surface characteristics (chemistries of nano-surface oxides, amphoteric OH group adsorbed on oxides, and oxide thickness) was effected by surface modification and three passivation methods (34% nitric acid passivation. 400 degrees C heated in air, and aged in 100 degrees C water). X-ray photoelectron spectroscopy and Auger electron spectroscopy were used for surface analyses. The chemistries of nano-surface oxides in a range studied should not change the capability of Ca and P adsorption. Nor is the capability affected significantly by amphoteric OH group and oxide thickness. However, passivations influence the surface oxide thickness and the early stage ion dissolution rate of the alloy. The rate-limiting step of the rate can be best explained by metal-ion transport through the oxide film, rather than hydrolysis of the film. Variation of the chemistries of titanium alloy alters the electromotive force potential of the metal, thereby affecting the corrosion and ion dissolution rate.

  2. Rotary condenser for SC2

    CERN Multimedia

    1975-01-01

    During 1975 the SC2 performance was improved among other things by redesigning some of the elements of the ROTCO (Annual Report 1975, p. 55). The photo shows an interior wiew of the housing of the rotary condenser and of the sixteen sets of shaped stator blades.

  3. and Deltamethrin 1% SC (Pali)

    African Journals Online (AJOL)

    control. During the experimental period (10 to 29 January 2011), the three groups of cattle were attended separately to avoid contacts. A high degree of efficacy of. Deltamethrin 1% pour-on (Smash) and Deltamethrin 1% SC (Pali) against single- and multi-host ticks was achieved by a single application of each product.

  4. Evaluation of the thermoluminescent detector answers of CaSO{sub 4}:Dy, LiF:Mg,Ti and micro LiF:Mg,Ti in photon clinical beams dosimetry using water simulator; Avaliacao da resposta de detectores termoluminescentes de CaSO4:Dy, LiF:Mg,Ti e microLiF:Mg,Ti na dosimetria de feixes clinicos de fotons utilizando simulador de agua

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, Luciana C.; Veneziani, Glauco R.; Campos, Leticia L., E-mail: lmatsushima@usp.b, E-mail: veneziani@ipen.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (GMR/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes; Sakuraba, Roberto K.; Cruz, Jose C. da, E-mail: rsakuraba@einstein.b, E-mail: jccruz@einstein.b [Sociedade Beneficente Israelita Brasileira, Sao Paulo, SP (Brazil). Hospital Albert Einstein (HAE)

    2011-10-26

    This paper perform the comparative study of thermoluminescent answer of calcium sulfate dosemeter doped with dysprosium (DaSO{sub 4}:Dy) produced by the IPEN, Sao Paulo, with answer of lithium fluoride dosemeters doped with magnesium and titanium (LiF:Mg, Ti) in the dosimetry of clinical beams of photons (6 and 15 MV) by using water simulator object. Dose-answer curves were obtained for gamma radiation of cobalt-60 in the air and in conditions of electronic equilibrium (plate of PMMA), and clinical photons of CLINAC model 2100C accelerators of the two evaluated hospitals: Hospital das Clinicas of the Faculty of Medicine of Sao Paulo university and Hospital Albert Einstein. It was also evaluated the sensitivity and reproduction of the three dosemeters

  5. Structural, elastic and thermodynamic properties of Ti2SC

    Indian Academy of Sciences (India)

    College of Physics and Electronic Information, Luoyang Normal College, Luoyang 471022, P.R. China; National Laboratory of Superhard Materials, Jilin University, Changchun 130012, P.R. China; College of Chemistry and Chemical Engineering, Luoyang Normal College, Luoyang 471022, P.R. China; Institute of Atomic ...

  6. Structural, dielectric and optical properties of sol-gel synthesized 0.55Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.45(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Jyoti; Yadav, K.L. [Indian Institute of Technology Roorkee, Smart Materials Research Laboratory, Department of Physics, Roorkee (India); Prakash, Satya [Indian Institute of Technology Roorkee, Metallurgical and Materials Engineering Department, Roorkee (India)

    2014-11-15

    Lead-free polycrystalline ceramic 0.55Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.45(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (0.55BZT-0.45BCT) was synthesized by sol-gel method and the dielectric, impedance and optical properties of this ceramic were studied. X-ray diffraction analysis revealed the formation of pure perovskite phase with the coexistence of tetragonal and rhombohedral structures. The high value of dielectric constant (∝6,985) with low dielectric loss (∝0.013) was obtained at room temperature. Bulk and grain boundary resistances were measured by impedance analysis, which revealed negative temperature coefficient of resistance behaviour in this ceramic. The estimated value of optical band gap was found to be ∝3.16 eV, which is related to the presence of intermediate energy levels. Two emission bands one at ∝365 nm (UV region) and another at ∝465 nm (blue region) were observed in photoluminescence spectrum at room temperature. (orig.)

  7. In situ transmission electron microscopy studies of microstructure evolution in Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} piezoceramic

    Energy Technology Data Exchange (ETDEWEB)

    Zakhozheva, Marina

    2016-10-21

    The purpose of this work is to understand the microstructural features which contribute to the strong electromechanical properties of the lead-free Ba (Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (BZT-xBCT) piezoelectric ceramic. Detailed conventional transmission electron microscopy (TEM) studies on a broad variety of BZT - xBCT were performed in order to demonstrate the composition dependent structural changes. Moreover, several in situ TEM techniques, including in situ hot- and cold-stage, in situ electric field and in situ electric field with simultaneous cooling, were successfully applied in order to monitor the domain morphology evolution in real time. By means of in situ temperature dependent TEM experiments it was shown that during rhombohedral → orthorhombic → tetragonal phase transition the domain morphology changed according to the crystal structure present. During in situ electric field investigations the displacement of the domain walls and changes in the domain configuration during electrical poling were observed, which indicates a high extrinsic contribution to the piezoelectric response in all BZT - xBCT compositions studied. From the results of in situ electric field TEM experiments with simultaneous cooling, we obtained experimental evidence that the further the composition deviates from the polymorphic phase boundary, the higher the electric field required to fully pole the material.

  8. Electric-field control of electronic transport properties and enhanced magnetoresistance in La0.7Sr0.3MnO3/0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 lead-free multiferroic structures

    Science.gov (United States)

    Yan, Jian-Min; Gao, Guan-Yin; Liu, Yu-Kuai; Wang, Fei-Fei; Zheng, Ren-Kui

    2017-10-01

    We report the fabrication of lead-free multiferroic structures by depositing ferromagnetic La0.7Sr0.3MnO3 (LSMO) polycrystalline films on polished 0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 (BZT-BCT) piezoelectric ceramic substrates. By applying electric fields to the BZT-BCT along the thickness direction, the resistivity of LSMO films can be effectively manipulated via the piezoelectric strain of the BZT-BCT. Moreover, the LSMO polycrystalline films exhibit almost temperature independent and significantly enhanced magnetoresistance (MR) below TC. At T = 2 K and H = 8 T, the MR of polycrystalline films is approximately two orders of magnitude higher than that of LSMO epitaxial films grown on (LaAlO3)0.3(SrAl1/2Ta1/2O3)0.7 single-crystal substrates. The enhanced MR mainly results from the spin-polarized tunneling of charge carriers across grain boundaries. The LSMO/BZT-BCT structures with electric-field controllable modulation of resistivity and enhanced MR effect may have potential applications in low-energy consumption and environmentally friendly electronic devices.

  9. Influence of Europium Doping on Various Electrical Properties of Low-Temperature Sintered 0.5Ba0.90Ca0.10TiO3-0.5BaTi0.88Zr0.12O3-0.1%CuO- xEu Lead-Free Ceramics

    Science.gov (United States)

    Tian, Yongshang; Li, Shuiyun; Sun, Shulin; Gong, Yansheng; Li, Tiantian; Yu, Yongshang; Jing, Qiangshan

    2018-01-01

    0.5Ba0.90Ca0.10TiO3-0.5BaTi0.88Zr0.12O3-0.1%CuO- xEu (BCT-BZT-Cu- xEu; x = 0-0.90%) lead-free ceramics were sintered at 1220°C with as-synthesized nanoparticles by a modified Pechini method. The structural characteristics and electrical properties of the ceramics that were influenced by varying europium-doping were investigated. All the ceramics featured high densification (relative density: ˜ 96%). X-ray powder diffraction results indicated the samples possessed pure orthorhombic phase. The maximum relative permittivity ( ɛ r, 10869) was found at x around 0.30%. Europium ions could dope on different substitution sites in the ABO3 lattice, which evidently influenced electrical properties with various volumes of oxygen vacancy. Moreover, the formation mechanisms of oxygen vacancy and defect electron complexes were stated. The piezoelectric properties were impacted by defect electron complexes, internal stress, ionic electronegativity, etc. The optimal electrical properties, i.e., d 33 = 384 pC/N, Q m = 92, and k p = 0.36, were detected at x = 0.45%.

  10. 2010 ARRA Lidar: Bamberg County (SC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Provide high density LiDAR elevation data map of Bamberg County, SC. Provide Bare Earth DEM (vegetation removal) of Bamberg County, SC.

  11. Polymorphic phase transition and morphotropic phase boundary in Ba{sub 1-x}Ca{sub x}Ti{sub 1-y}Zr{sub y}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Abdessalem, M. Ben; Aydi, S.; Aydi, A.; Abdelmoula, N.; Khemakhem, H. [Universite de Sfax, Faculte des Sciences de Sfax (FSS), Laboratoire des Materiaux Multifonctionnels et Applications (LaMMA) LR16ES18, B.P.1171, Sfax (Tunisia); Sassi, Z. [Laboratoire de Genie Electrique et Ferroelectricite (LGEF) de L' INSA de Lyon, Lyon (France)

    2017-09-15

    This paper deals with Ca and Zr co-doped BaTiO{sub 3} (BCTZ{sub (x,} {sub y)}) (x = 0.1, 0.13, 0.2 and y = 0.05, 0.1, 0.15). These ceramics were prepared using the conventional solid state method. The symmetry, dielectric properties, Raman spectroscopy, ferroelectric behavior and piezoelectric effect were examined. X-ray diffraction (XRD) results display that morphotropic boundary occurs from tetragonal to orthorhombic region of BCZT{sub (x=0.1,} {sub 0.2,} {sub y=0.05,} {sub 0.1)} and polymorphic phase transitions from tetragonal to orthorhombic, orthorhombic to rhombohedral regions of BCZT{sub (x=0.13,} {sub y=0.1)}. The evolution of the Raman spectra was investigated as a function of compositions at room temperature, in correlation with XRD analysis and dielectric measurements. We note that the substitution of Ca in Ba site and Zr ions in Ti site slightly decreased the cubic-tetragonal temperature transition (T{sub C}) and increased the orthorhombic-tetragonal (T{sub 1}) and rhombohedral-orthorhombic (T{sub 2}) temperatures transitions. The ferroelectric properties were examined by a P-E hysteresis loop. The two parameters ΔT{sub 1} and ΔT{sub 2} are defined as ΔT{sub 1} = T{sub C} - T{sub 1} and ΔT{sub 2} = T{sub C} - T{sub 2}, they come close to T{sub C} for x = 0.13, y = 0.1, which reveals that this composition is around the polymorphic phase. The excellent piezoelectric coefficient of d{sub 33} = 288 pC N{sup -1}, the electromechanical coupling factor k{sub p} = 40%, high constant dielectric 9105, coercive field E{sub c} = 0.32 (KV mm{sup -1}) and remanent polarization P{sub r} = 0.1 (μc mm{sup -2}) were obtained for composition x = 0.13, y = 0.1. (orig.)

  12. Microstructural characterization and interactions in Ti- and TiH2-hydroxyapatite vacuum sintered composites

    Directory of Open Access Journals (Sweden)

    Marcelo Teresa Maria

    2006-01-01

    Full Text Available Titanium/hydroxyapatite (HAP composites are candidate materials for biomedical applications as implants and hard tissue substitutes since they combine the good mechanical properties and biocompatibility of Ti with the excellent HAP bioactivity and osteointegration. In powder metallurgy processing of these composites, HAP decomposition promoted by Ti during powder sintering is found. In a previous work Ti-50v%HAP greens of 60% theoretical density (dT were vacuum sintered at 1150 degreesC and formation of CaO and Ca4O(PO42 (TTCP resulting from the HAP decomposition, as well as Ti4P3 at the Ti/HAP interfaces was obtained. In the present work those composites are compared with similar ones processed from TiH2 as a substitute for Ti which were also vacuum sintered at 1150 degreesC from greens with 60 to 86%dT. For the lower %dT, the compounds formed were CaO, TTCP and Ti4P3 and for the higher %dT ones, besides those same products, CaTiO3, Ti5P3 and a phase containing Ti, Ca and P were detected.

  13. Investigation of the structural, optical and dielectric properties of highly (1 0 0)-oriented (Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20})TiO{sub 3} thin films on LaNiO{sub 3} bottom electrode

    Energy Technology Data Exchange (ETDEWEB)

    Pontes, D.S.L. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Pontes, F.M., E-mail: fenelon@fc.unesp.br [Department of Chemistry, Universidade Estadual Paulista, P.O. Box 473, 17033-360 Bauru, São Paulo (Brazil); Chiquito, A.J. [NanO LaB, Transporte Eletrônico em Nanoestruturas, Department of Physics, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Longo, E. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Institute of Chemistry, Universidade Estadual Paulista, Araraquara, São Paulo (Brazil)

    2014-07-01

    Highlights: • Highly (h 0 0) oriented LNO and PCST thin films were grown on LAO(1 0 0) substrate. • PCST/LNO/LAO structure shown classic ferroelectric–paraelectric phase transition. • PCST/LNO/LAO structure shows superior dielectric properties. • PCST/LAO films showed a direct allowed optical transition. - Abstract: Highly (1 0 0)-oriented Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure was fabricated using a chemical deposition process via spin-coating technique. XRD revealed that both LNO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films grown on LAO(1 0 0) substrate and LNO/LAO(1 0 0) structure were crystallized to be highly (h 0 0)-oriented, respectively. AFM images revealed smooth surfaces, spherical-shaped grains and a crack-free surface with a roughness of about 3–7 nm. The tetragonal perovskite phase was confirmed by Raman spectroscopy for Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LAO structures. The optical transmittance of 340 nm thick Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films on a LAO(1 0 0) substrate exhibited an average transmittance above 80% in the wavelength range of 500–1000 nm and an optical band gap E{sub g} of 3.56 and 2.87 eV for the direct and indirect transition processes, respectively. The Au/Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure has a hysteresis loop with remnant polarization, P{sub r}, of 12 μC/cm{sup 2}, and a coercive field, E{sub c}, of 46 kV/cm for an electric field at 370 kV/cm along with a dielectric constant over 1200.

  14. Structural analysis, optical and dielectric function of [Ba{sub 0.9}Ca{sub 0.1}](Ti{sub 0.9}Zr{sub 0.1})O{sub 3} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Pérez, G., E-mail: guillermo.herrera@cimav.edu.mx, E-mail: damasio.morales@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Physics of Materials Department, Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Morales, D., E-mail: guillermo.herrera@cimav.edu.mx, E-mail: damasio.morales@cimav.edu.mx; Paraguay-Delgado, F.; Reyes-Rojas, A.; Fuentes-Cobas, L. E. [Physics of Materials Department, Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Borja-Urby, R. [Centro de Nanociencias Micro y Nanotecnologías, Instituto Politécnico Nacional, 07300 México City (Mexico)

    2016-09-07

    This work presents the identification of inter-band transitions in the imaginary part of the dielectric function (ε{sub 2}) derived from the Kramers–Kronig analysis for [Ba{sub 0.9}Ca{sub 0.1}](Ti{sub 0.9}Zr{sub 0.1})O{sub 3} (BCZT) nanocrystals synthesized by the modified Pechini method. The analysis started with the chemical identification of the atoms that conform BCZT in the valence loss energy region of a high energy-resolution of electron energy loss spectroscopy. The indirect band energy (E{sub g}) was determined in the dielectric response function. This result is in agreement with the UV-Vis technique, and it obtained an optical band gap of 3.16 eV. The surface and volume plasmon peaks were observed at 13.1 eV and 26.2 eV, respectively. The X-ray diffraction pattern and the Rietveld refinement data of powders heat treated at 700 °C for 1 h suggest a tetragonal structure with a space group (P4 mm) with the average crystal size of 35 nm. The average particle size was determined by transmission electron microscopy.

  15. Dielectric and pyroelectric properties of poled Ba{sub 0.6}Sr{sub 0.3}Ca{sub 0.1}TiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Sheng; Mao, Chaoliang; Yao, Chunhua; Liu, Wei; Li, Kui; Cao, Fei; Dong, Xianlin; Wang, Genshui [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 DingXi Road, Shanghai 200050 (China)

    2011-05-15

    Ba{sub 0.6}Sr{sub 0.3}Ca{sub 0.1}TiO{sub 3} ceramics were prepared by solid-state reaction technique and the dielectric and pyroelectric properties of poled specimens were systemically investigated. The dielectric constant and dielectric loss at Curie temperature for the poled specimens were 11 273 and 0.0152, respectively. The pyroelectric coefficient maximum about 40 x 10{sup -8} C cm{sup -2} K{sup -1} was detected and the figure of merit (F{sub d}) maximum about 9.77 x 10{sup -5} Pa{sup -1/2} was obtained when 800 V mm{sup -1} bias field was applied on the poled specimens. Based on the dielectric and pyroelectric data, the behaviors of the intrinsic pyroelectric response and the field induced pyroelectric response under DC bias field were also discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Lead-free Ba{sub 0.8}Ca{sub 0.2}(Zr{sub x}Ti{sub 1−x})O{sub 3} ceramics with large electrocaloric effect

    Energy Technology Data Exchange (ETDEWEB)

    Asbani, B. [LPMC, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cédex (France); LMCN, F.S.T.G. Université Cadi Ayyad, BP 549 Marrakech (Morocco); Dellis, J.-L.; Lahmar, A.; Gagou, Y.; El Marssi, M., E-mail: mimoun.elmarssi@u-picardie.fr [LPMC, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cédex (France); Courty, M.; Djellab, K. [LRCS, UMR7314, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cédex (France); Amjoud, M.; Mezzane, D. [LMCN, F.S.T.G. Université Cadi Ayyad, BP 549 Marrakech (Morocco); Kutnjak, Z. [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia)

    2015-01-26

    The electrocaloric effect was investigated in lead-free Zr doped Ba{sub 0.8}Ca{sub 0.2}(Zr{sub x}Ti{sub 1−x})O{sub 3} (BCTZ) ceramics synthesized by a conventional sintering process. Room-temperature x-ray diffraction analysis showed that the tetragonal structure is obtained in BCTZ for x ≤ 0.08 and a pseudo cubic phase for x > 0.08. The dielectric spectroscopy and calorimetry revealed that the Curie temperature decreases as a consequence of Zr doping and that the BCTZ exhibits a first order ferroelectric phase transition. The electrocaloric effect was determined by the calculation of the electrocaloric change of temperature (ΔT) using the Maxwell relation based on the P–E hysteresis loops measured at different temperatures. A large electrocaloric responsivity ΔT/ΔE = 0.34 × 10{sup −6 }Km/V was found for x = 0.04, which significantly exceeds of values found so far in other lead-free electrocaloric materials.

  17. Preparation of (11n) oriented Bi2Sr2CaCu2O8+x thin films without c-axis twin structure by the metal-organic decomposition method using vicinal SrTiO3 (110) substrates

    Science.gov (United States)

    Yamada, Yasuyuki; Kato, Takahiro; Ishibashi, Takayuki; Okamoto, Tomoichiro; Mori, Natsuki

    2018-01-01

    We have prepared (11n) oriented Bi2Sr2CaCu2O8+x (Bi2212) thin films by metal-organic decomposition method. The vicinal (110) substrate of SrTiO3 (STO) inclined toward the [1 ¯ 10] direction was used for suppressing "c-twinning". In the sample prepared in the O2 atmosphere, only the (11n) peak appeared in the θ-2θ X-ray diffraction pattern. When the miscut angle of the substrate was φ = 10°, it was shown by the scanning electron microscope images and the (008) pole figures that the c-axis was inclined by about 38° and the c-twinning was substantially suppressed. ρab and ρc of this sample were calculated by the corrected van der Pauw method and component calculation of the two-dimensional resistivity tensor. The superconducting transition temperatures were Tc = 81 K. The temperature dependence of ρab was a typical metallic behavior reflecting the characteristics of the ab-plane of Bi2212. On the other hand, that of ρc did not become a typical semiconductor behavior in the c-axis direction of Bi2212, but it showed a metallic behavior. The anisotropic parameter γ was about 10.

  18. Coupling of electric charge and magnetic field via electronic phase separation in (La,Pr,Ca)MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3 multiferroic heterostructures

    Science.gov (United States)

    Zheng, Ming; Wang, Wei

    2016-04-01

    The electric-field-tunable non-volatile resistivity and ferromagnetism switching in the (La0.5Pr0.5)0.67Ca0.33MnO3 films grown on (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ferroelectric single-crystal substrates have been investigated. By combining the 180° ferroelectric domain switching and in situ X-ray diffraction and resistivity measurements, we identify that this voltage control of order parameters stems from the domain switching-induced accumulation/depletion of charge carriers at the interface rather than induced lattice strain effect. In particular, the polarization-induced charge effect (i.e., ferroelectric field effect) is strongly dependent on the magnetic field. This, together with the charge-modulated magnetoresistance and magnetization, reveals the strong correlation between the electric charge and the magnetic field. Further, we found that this coupling is essentially driven by the electronic phase separation, the relative strength of which could be determined by recording charge-tunability of resistivity [ (Δρ/ρ)c h arg e ] under various magnetic fields. These findings present a potential strategy for elucidating essential physics of perovskite manganites and delivering prototype electronic devices for non-volatile information storage.

  19. Structural and electrical properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3} films deposited on differently oriented SrTiO{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Aydogdu, G.H. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart D-70569 (Germany)], E-mail: G.Aydogdu@fkf.mpg.de; Kuru, Y. [Max Planck Institute for Metals Research, Heisenbergstr. 3, Stuttgart D-70569 (Germany)], E-mail: y.kuru@mf.mpg.de; Habermeier, H.-U. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart D-70569 (Germany)], E-mail: huh@fkf.mpg.de

    2007-11-25

    La{sub 0.5}Ca{sub 0.5}MnO{sub 3} (LCMO) films of various thicknesses were epitaxially grown on (1 0 0) and (1 1 1) oriented SrTiO{sub 3} (STO) substrates by pulsed laser deposition (PLD) technique. It was observed that LCMO films on (1 0 0) STO behave as an insulator. However, the films on (1 1 1) STO show a metal to insulator transition, when their thicknesses exceed 145 nm. Jahn-Teller strain ({epsilon}{sub J-T}) was seen to decrease with increasing film thickness for the films on (1 1 1) STO while the films on (1 0 0) STO have large compressive {epsilon}{sub J-T} values for all thicknesses. Moreover, rocking curves and asymmetries of the diffraction peaks for the films on (1 1 1) STO substrates may indicate the formation of a mosaic structure, which can act as a relaxation mechanism, with the increasing film thickness. These observations suggest that the electronic properties of the LCMO thin films can be modified by structural changes imposed by the substrate.

  20. Investigating the influence of Na+ and Sr2+ on the structure and solubility of SiO2-TiO2-CaO-Na2O/SrO bioactive glass.

    Science.gov (United States)

    Li, Y; Placek, L M; Coughlan, A; Laffir, F R; Pradhan, D; Mellott, N P; Wren, A W

    2015-02-01

    This study was conducted to determine the influence that network modifiers, sodium (Na+) and strontium (Sr2+), have on the solubility of a SiO2-TiO2-CaO-Na2O/SrO bioactive glass. Glass characterization determined each composition had a similar structure, i.e. bridging to non-bridging oxygen ratio determined by X-ray photoelectron spectroscopy. Magic angle spinning nuclear magnetic resonance (MAS-NMR) confirmed structural similarities as each glass presented spectral shifts between -84 and -85 ppm. Differential thermal analysis and hardness testing revealed higher glass transition temperatures (Tg 591-760 °C) and hardness values (2.4-6.1 GPa) for the Sr2+ containing glasses. Additionally the Sr2+ (~250 mg/L) containing glasses displayed much lower ion release rates than the Na+ (~1,200 mg/L) containing glass analogues. With the reduction in ion release there was an associated reduction in solution pH. Cytotoxicity and cell adhesion studies were conducted using MC3T3 Osteoblasts. Each glass did not significantly reduce cell numbers and osteoblasts were found to adhere to each glass surface.

  1. Structural, electric and dielectric properties of Ca0.85Er0.1Ti1- x Co4 x/3O3(0 ≤ x ≤ 0.1)

    Science.gov (United States)

    Rayssi, Ch.; Rhouma, F. I. H.; Dhahri, J.; Khirouni, K.; Zaidi, M.; Belmabrouk, Hafedh

    2017-12-01

    The structural and physical properties of Ca0.85Er0.1Ti1- x Co4 x/3O3 (CETCo x ) ( x = 0.00, 0.05 and 0.10), synthesized by sol-gel method were studied. The polycrystalline sample of CETCo x was investigated by X-ray diffraction and morphological properties by scanning electron microscopy (SEM) as well as the electrical characterizations. A single orthorhombic perovskite structure with a Pbnm space group was obtained. The electrical properties were studied by impedance complex spectroscopy in the frequency range (102-107 Hz) at different temperatures. The electrical properties showed that all samples have a semiconductor behavior. Conductivity decreased with increasing Co rate. At a specific temperature, a saturation region was marked in the conductivity curve as a function of temperature. From the curve of the average normalized change with temperature dependence, we deduced the temperature in which the density of trapped charge is vanished, confirming the saturation which appears at the temperature dependence of conductivity. The complex impedance analysis confirmed the existence of electrical relaxation in the materials, which may be responsible for the electrical conduction. CETCo x presented a decrease of the real and imaginary part of permittivity and dielectric loss with increasing frequency. This can be explained by Maxwell-Wagner type of polarization in accordance with Koop's theory and can also explain the increase of conductivity with frequency.

  2. Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, a new mineral from nepheline syenite pegmatite in the Sakharjok massif, Kola Peninsula, Russia

    Science.gov (United States)

    Lyalina, L. M.; Zolotarev, A. A.; Selivanova, E. A.; Savchenko, Ye. E.; Krivovichev, S. V.; Mikhailova, Yu. A.; Kadyrova, G. I.; Zozulya, D. R.

    2016-12-01

    Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, is a new mineral found in nepheline syenite pegmatite in the Sakharjok alkaline massif, Western Keivy, Kola Peninsula, Russia. The pegmatite mainly consists of nepheline, albite, alkali pyroxenes, amphiboles, biotite and zeolites. Batievaite-(Y) is a late-pegmatitic or hydrothermal mineral associated with meliphanite, fluorite, calcite, zircon, britholite-group minerals, leucophanite, gadolinite-subgroup minerals, titanite, smectites, pyrochlore-group minerals, zirkelite, cerianite-(Ce), rutile, behoite, ilmenite, apatite-group minerals, mimetite, molybdenite, and nickeline. Batievaite-(Y) is pale-cream coloured with white streak and dull, greasy or pearly luster. Its Mohs hardness is 5-5.5. No cleavage or parting was observed. The measured density is 3.45(5) g/cm3. Batievaite-(Y) is optically biaxial positive, α 1.745(5), β 1.747(5), γ 1.752(5) (λ 589 nm), 2 V meas. = 60(5)°, 2 V calc. = 65°. Batievaite-(Y) is triclinic, space group P-1, a 9.4024(8), b 5.5623(5), c 7.3784(6) Å, α 89.919(2), β 101.408(2), γ 96.621(2)°, V 375.65(6) Å3 and Z = 1. The eight strongest lines of the X-ray powder diffraction pattern [ d(Å)(I)( hkl)] are: 2.991(100)(11-2), 7.238(36)(00-1), 3.061(30)(300), 4.350(23)(0-1-1), 9.145(17)(100), 4.042(16)(11-1), 2.819(16)(3-10), 3.745(13)(2-10). The chemical composition determined by electron probe microanalysis (EPMA) is (wt.%): Nb2O5 2.25, TiO2 8.01, ZrO2 2.72, SiO2 29.96, Al2O3 0.56, Fe2O3 0.43, Y2O3 11.45, La2O3 0.22, Ce2O3 0.33, Nd2O3 0.02, Gd2O3 0.07, Dy2O3 0.47, Er2O3 1.07, Tm2O3 0.25, Yb2O3 2.81, Lu2O3 0.45, CaO 24.98, MnO 1.31, MgO 0.01, Na2O 1.13, K2O 0.02, F 2.88, Cl 0.19, H2O 6.75 (determined on the basis of crystal structure data), O = (F,Cl) -1.25, total 97.09 wt.%. The empirical formula based on the EPMA and single-crystal structure analyses is (Y0.81Ca0.65Mn0.15Zr0.12Yb0.11Er0.04Fe3+ 0.04Ce0.02Dy0.02Lu0.02La0.01Tm0.01)Σ2.00((H2O)0.75Ca0.70□0.55)Σ2.00Ca2.00(□0.61Na0

  3. First measurement of the nonlinear coefficient for Gd1-xLux Ca4O(BO3)3 and Gd1-xScxCa4O(BO3)3 crystals

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Mortensen, Jesper Liltorp; Germershausen, Sven

    2007-01-01

    The effective nonlinear coefficient and temperature acceptance bandwidth of three Lu and Sc co-doped GdCa4O(B03)3 type nonlinear crystals were measured. NCPM for SHG in to the blue-UV spectral region can be obtained by controlling the co-dopant concentration. Measurements were based on intra......-cavity SHG of a CW Ti:Sapphire laser, and the effective nonlinear coefficients were found to be in the range of 0.5 to 0.6 pm/V for the three crystals used. The FWHM temperature acceptance bandwidth was measured to be more than 35 °C using a 6 mm long Gd0.871Lu0.129Ca4O(BO3)3 crystal. A maximum of 115 m......W at 407.3 nm in a single direction was measured using a 6.5 mm long Gd0.96Sc 0.04CaO(BO3)3 crystal....

  4. Structural properties of CaTi{sub 1-x}(Nb{sub 2/3}Li{sub 2/3}){sub x}O{sub 3-d}elta (CNLTO) and CaTi{sub 1-x}(Nb{sub 1/2}Ln{sub 1/2}){sub x}O{sub 3} (Ln=Fe (CNFTO), Bi (CNBTO)), modified dielectric ceramics for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Costa, R.C.S. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil); Departamento de Engenharia de Teleinformatica, CP 6007, Universidade Federal do Ceara, CEP 60455-760, Fortaleza, Ceara (Brazil); Bruno Costa, A.D.S. [Departamento de Engenharia de Teleinformatica, CP 6007, Universidade Federal do Ceara, CEP 60455-760, Fortaleza, Ceara (Brazil); Freire, F.N.A.; Santos, M.R.P.; Almeida, J.S.; Sohn, R.S.T.M. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil); Sasaki, J.M. [Laboratorio de Raios-X, Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil); Sombra, A.S.B., E-mail: sombra@fisica.ufc.b [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil)

    2009-05-01

    This paper presents an investigation of the structural characteristics of Nb{sub 1/2}Bi{sub 1/2} (CNBTO), Nb{sub 1/2}Fe{sub 1/2} (CNFTO) and Nb{sub 2/3}Li{sub 1/3} (CNLTO) substitution into the B-site of calcium titanate ceramics. The modified CaTiO{sub 3} (CTO) ceramics were prepared by the conventional solid-state method. The compounds were investigated, by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS). The X-ray analysis shows that all samples have an orthorhombic structure. The refinement analysis of all samples were also performed and discussed in this paper. For all studied samples, a Raman mode at 805 cm{sup -1} was detected and its intensity increases as the substitution increases. The dielectric permittivity and loss at microwave frequencies (MW) were investigated. The CNLTO phase, present the highest dielectric constant (k=35.8) at 3.9 GHz with loss (tg alpha=7x10{sup -3}). The lowest value of k=25.7 (f=4.8 GHz) and tg alpha=3x10{sup -3}, was obtained for the CNFTO phase. These measurements confirm the possible use of such material for microwave devices like dielectric resonator antennas.

  5. Atomistic modeling of ternary additions to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt and Ni-Ti-Hf shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mosca, H.O., E-mail: hmosca@cnea.gov.ar [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, B1650KNA San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Bozzolo, G. [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Grosso, M.F. del [Gcia. Investigacion y Aplicaciones, CNEA, Av. Gral Paz 1499, B1650KNA San Martin (Argentina); GCMM, UTN, FRG Pacheco, Av. H. Yrigoyen 288, Gral. Pacheco (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina)

    2012-08-15

    The behavior of ternary and quaternary additions to NiTi shape memory alloys is investigated using a quantum approximate method for the energetics. Ternary additions X to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt, and Ni-Ti-Hf alloys, for X=Au, Pt, Ir, Os, Re, W, Ta,Ag, Pd, Rh, Ru, Tc, Mo, Nb, Zr, Zn, Cu, Co, Fe, Mn, V, Sc, Si, Al and Mg are considered. Bulk properties such as lattice parameter, energy of formation, and bulk modulus of the B2 alloys are studied for variations due to the presence of one or two simultaneous additives.

  6. Fabrication of CaO-ZrO{sub 2}-TiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} glasses and glass-ceramics. Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jing-Shi; Shen, Pouyan [Institute of Materials Science and Engineering, National Sun Yat-sen University, Kaohsiung (Taiwan, Province of China)

    1996-09-01

    The CaO-ZrO{sub 2}-TiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} glass, a potential glaze, solder and immobilizer of high-level radioactive wastes, was prepared from the powder batches of CaO-ZrO{sub 2}-TiO{sub 2} (C{sub 5}ZT, subscripts are molar ratios) with the additives of B{sub 2}O{sub 3}, SiO{sub 2} and Al{sub 2}O{sub 3} and at a firing temperature of 1200C. Upon heating (10C/min) for differential thermal analysis, all the glasses went through a glass transition event at 640C (peak temperature) and then two devitrification events at 800 and 900C, which caused the formation of m-ZrO{sub 2} and ZrO{sub 2}-derived phases (predominantly zirconolite, CaZrTi{sub 2}O{sub 7}), respectively. Glass-ceramics were further fabricated from the glass slabs by one-stage heating at 900C, which caused first the cellular layer and then spherulitic clusters of ZrO{sub 2} derivatives. When the glass-ceramics were subjected to prolonged annealing, the ZrO{sub 2}-derived phases always survived while borate, silicate and other phases appeared. The selection of zirconia-related phases during devitrification are discussed.

  7. Quaternary equilibrium diagrams ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}). A powerful tool for the development of new materials by reaction sintering; Diagramas de equilibrio cuaternarios ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}- (CaO, MgO, TiO{sub 2}). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterizacion reactiva

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported. (Author) 42 refs.

  8. Academic Training - Pulsed SC Magnets

    CERN Multimedia

    Françoise Benz

    2006-01-01

    2005-2006 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 2, 3, June 29, 30, 31 May, 1, 2 June 11:00-12:00 - Auditorium, bldg 500 Pulsed SC Magnets by M. Wilson Lecture 1. Introduction to Superconducting Materials Type 1,2 and high temperature superconductors; their critical temperature, field & current density. Persistent screening currents and the critical state model. Lecture 2. Magnetization and AC Loss How screening currents cause irreversible magnetization and hysteresis loops. Field errors caused by screening currents. Flux jumping. The general formulation of ac loss in terms of magnetization. AC losses caused by screening currents. Lecture 3. Twisted Wires and Cables Filamentary composite wires and the losses caused by coupling currents between filaments, the need for twisting. Why we need cables and how the coupling currents in cables contribute more ac loss. Field errors caused by coupling currents. Lecture 4. AC Losses in Magnets, Cooling and Measurement Summary of all loss mech...

  9. Synthesis, kinetic analysis and electrical characterization of (Ca{sub 0.8}Sr{sub 0.2}){sub 0.6}La{sub 0.267}TiO{sub 3} by polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Naeem, Abdul [National Centre of Excellence in Physical Chemistry, University of Peshawar, 25120 (Pakistan); Ullah, Asad, E-mail: asadncepc@upesh.edu.pk [National Centre of Excellence in Physical Chemistry, University of Peshawar, 25120 (Pakistan); Iqbal, Yaseen [Material Research Centre, Department of Physics, University of Peshawar, 25120 (Pakistan); Mahmood, Tahira; Mahmood, Asad [National Centre of Excellence in Physical Chemistry, University of Peshawar, 25120 (Pakistan); Raza, Zulfiqar Ali [National Textile University, Faisalabad, 25120 (Pakistan)

    2016-07-05

    (Ca{sub 0.8}Sr{sub 0.2}){sub 0.6}La{sub 0.267}TiO{sub 3} microwave dielectric ceramic was synthesized by a polymeric precursor method. The kinetic and thermodynamic parameters of the reaction were determined by a non-isothermal method. The activation energy of thermal decomposition of the polymeric precursor was found to be 70.97 ± 5.67 kJ/mol and 63.62 ± 6.03 kJ/mol using FWO and KAS models respectively. The average values of thermodynamic parameters were; ΔH{sup *} = 120.57 kJ/mol, ΔG{sup *} = 282.94 kJ/mol and ΔS{sup *} = −223.93 J/mol K. The particle size of the synthesized powder was <100 nm with orthorhombic (Pbnm) symmetry. The sintered ceramic exhibited ε{sub r} = 116.2, Q × ƒ = 15730 and τ{sub ƒ} = +231 ppm/°C. Analysis of impedance data obtained in the temperature range 200–500 °C revealed that the ceramic exhibited negative temperature coefficient resistor (NTCR) characteristics. - Highlights: • Thermal decomposition kinetic of polymeric precursor was studied. • Isoconversional models of FWO and KAS were used to access kinetic parameter. • CSLT showed ε{sub r} = 116.2, Q × ƒ = 15730 (GHz) and τ{sub f} = +231 ppm/K. • Impedance study revealed that the composition is NTCR type ceramic.

  10. Dielectric, Piezoelectric, and Vibration Properties of the LiF-Doped (Ba0.95Ca0.05(Ti0.93Sn0.07O3 Lead-Free Piezoceramic Sheets

    Directory of Open Access Journals (Sweden)

    Chien-Min Cheng

    2018-01-01

    Full Text Available By the conventional solid state reaction method, a small amount of lithium fluoride (LiF was used as the sintering promoter to improve the sintering and piezoelectric characteristics of (Ba0.95Ca0.05(Ti0.93Sn0.07O3 (BCTS lead-free piezoceramic sheets. Using X-ray diffraction (XRD and a scanning electron microscope (SEM, the inferences of the crystalline and surface microstructures were obtained and analyzed. Then, the impedance analyzer and d33-meter were used to measure the dielectric and piezoelectric characteristics. In this study, the optimum sintering temperature of the BCTS sheets decreased from 1450 °C to 1390 °C due to LiF doping. For the 0.07 wt % LiF-doped BCTS sheets sintered at 1390 °C, the piezoelectric constant (d33 is 413 pC/N, the electric–mechanical coupling coefficient (kp is 47.5%, the dielectric loss (tan δ is 3.9%, and the dielectric constant (εr is 8100, which are all close to or even better than that of the pure undoped BCTS ceramics. The Curie temperature also improved, from 85 °C for pure BCTS to 140 °C for BCTS–0.07 LiF sheets. Furthermore, by using the vibration system and fixing 1.5 g tip mass at the end of the sheets, as the vibration frequency is 20 Hz, the proposed piezoelectric ceramic sheets also reveal a good energy harvesting performance at the maximum output peak voltage of 4.6 V, which is large enough and can be applied in modern low-power electronic products.

  11. Enhanced piezoelectric properties and excellent thermal stabilities of cobalt-modified Aurivillius-type calcium bismuth titanate (CaBi{sub 4}Ti{sub 4}O{sub 15})

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Tian-Long [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Wang, Chun-Ming, E-mail: wangcm@sdu.edu.cn [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Wang, Chun-Lei; Wang, Yi-Ming [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Dong, Shuxiang [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2015-11-15

    Highlights: • Cobalt oxide modified CBT-based ceramics were prepared and investigated in detail. • XRPD analysis revealed Co ions enter into B-site of CBT-based ceramics. • CBT-Co4 ceramics show the enhanced d{sub 33} of 14 pC/N and T{sub c} of 782 °C. • CBT-Co4 ceramics present the improved high-temperature resistivity. • Thermal depoling behavior indicates CBT-Co4 ceramics exhibit good thermal stability. - Abstract: Bismuth layer-structured ferroelectric (BLSF) calcium bismuth titanate (CaBi{sub 4}Ti{sub 4}O{sub 15}, CBT) piezoelectric ceramics with 0.0–1.0 wt.% cobalt oxide (Co{sub 2}O{sub 3}) have been prepared via a conventional solid-state reaction method. Microstructural morphology and electrical properties of cobalt oxide-modified CBT ceramics were investigated in detail. X-ray powder diffraction (XRPD) analysis revealed that the cobalt oxide-modified CBT ceramics have a pure four-layer Aurivillius-type structure. The piezoelectric properties of CBT ceramics were significantly enhanced by cobalt oxide modifications. The piezoelectric coefficient d{sub 33} and Curie temperature T{sub c} of 0.2 wt.% cobalt oxide-modified CBT ceramics (CBT-Co4) are 14 pC/N and 782 °C, respectively. The DC resistivity and thermal depoling behavior at elevated temperature indicated that the CBT-Co4 ceramics exhibit good thermal stability, demonstrating that the CBT-Co4 ceramics are potential materials for high temperature piezoelectric applications.

  12. CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

    KAUST Repository

    Rydén, Magnus

    2011-03-01

    Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor system. For the oxygen uncoupling experiments, it was found that the particles released O2 in gas phase at temperatures above 720°C when the fuel reactor was fluidized with CO2. The effect increased with increased temperature, and with the O2 partial pressure in the air reactor. At 950°C, the O2 concentration in the outlet from the fuel reactor was in the order of 4.0vol%, if the particles were oxidized in air. For the chemical-looping combustion experiments the combustion efficiency with standard process parameters was in the order of 95% at 950°C, using 1000kg oxygen carrier per MW natural gas, of which about 30% was located in the fuel reactor. Reducing the fuel flow so that 1900kg oxygen carrier per MW natural gas was used improved the combustion efficiency to roughly 99.8%. The particles retained their physical properties, reactivity with CH4 and ability to release gas-phase O2 reasonably well throughout the testing period and there were no problems with the fluidization or formation of solid carbon in the reactor. X-ray diffraction showed that the particles underwent changes in their phase composition though. © 2010 Elsevier Ltd.

  13. Electrolytic Production of Ti5Si3/TiC Composites by Solid Oxide Membrane Technology

    Science.gov (United States)

    Zheng, Kai; Zou, Xingli; Xie, Xueliang; Lu, Changyuan; Chen, Chaoyi; Xu, Qian; Lu, Xionggang

    2018-02-01

    This paper investigated the electrolytic production of Ti5Si3/TiC composites from TiO2/SiO2/C in molten CaCl2. The solid-oxide oxygen-ion-conducting membrane tube filled with carbon-saturated liquid tin was served as the anode, and the pressed spherical TiO2/SiO2/C pellet was used as the cathode. The electrochemical reduction process was carried out at 1273 K and 3.8 V. The characteristics of the obtained cathode products and the reaction mechanism of the electroreduction process were studied by a series of time-dependent electroreduction experiments. It was found that the electroreduction process generally proceeds through the following steps: TiO2/SiO2/C → Ti2O3, CaTiO3, Ca2SiO4, SiC → Ti5Si3, TiC. The morphology observation and the elemental distribution analysis indicate that the reaction routes for Ti5Si3 and TiC products are independent during the electroreduction process.

  14. 46 CFR 7.70 - Folly Island, SC to Hilton Head Island, SC.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Folly Island, SC to Hilton Head Island, SC. 7.70 Section... BOUNDARY LINES Atlantic Coast § 7.70 Folly Island, SC to Hilton Head Island, SC. (a) A line drawn from the southernmost extremity of Folly Island to latitude 32°35′ N. longitude 79°58.2′ W. (Stono Inlet Lighted Whistle...

  15. Electromagnetic switches, NEO SC Series; Denji kaiheiki NEO SC series

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-01-10

    The medium to large size electromagnetic switches, NEO SC Series were developed under the following five concepts: 'internationality,' 'safety,' 'practical applicability,' 'compactness' and 'environmentality'. Under the circumstances that safety and environmentality are given greater importance, internationalization of the JIS standard is in progress. These switches are the global products that are based on the newly established JIS standard and the international standard, and have acquired certification for the overseas standards in the standard products. Assurance of quick supply of the products including maintenance parts contribute to convenience of the customers. Enhancement was made on the performance to prevent consequential accident in the event of short circuit accident, as well as on the arc space free structure and safety as a result of making a full product line, including terminal covers and intra-phase barriers. Practical applicability was enhanced by expanding models attached with rails, and increasing the operating ambient temperature to 55 degrees C, and the coverage of additional auxiliary contacts. (translated by NEDO)

  16. Radiation Protection Section (SC/SL/RP)

    CERN Multimedia

    2006-01-01

    We should like to inform you that the Radiation Protection Section (SC/SL/RP) located on the Prévessin site has moved from Building 865 (ground floor) to new premises in Wing A of Building 892 (second floor). Telephone numbers remain the same. SC/SL/RP section

  17. rotor of the SC rotating condenser

    CERN Multimedia

    1974-01-01

    The rotor of the rotating condenser was installed instead of the tuning fork as the modulating element of the radiofrequency system, when the SC accelerator underwent extensive improvements between 1973 to 1975 (see object AC-025). The SC was the first accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990.

  18. Dopamine-modified TiO2 monolith-assisted LDI MS imaging for simultaneous localization of small metabolites and lipids in mouse brain tissue with enhanced detection selectivity and sensitivity† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc00937b Click here for additional data file.

    Science.gov (United States)

    Wu, Qian; Chu, James L.; Rubakhin, Stanislav S.; Gillette, Martha U.

    2017-01-01

    Localization of metabolites using multiplexed mass spectrometry imaging (MSI) provides important chemical information for biological research. In contrast to matrix-assisted laser desorption/ionization (MALDI), TiO2-assisted laser desorption/ionization (LDI) for MSI improves detection of low molecular mass metabolites (monolithic TiO2-DA structures. The sub-micron scale and higher surface pH of the TiO2 particle sizes led to improved detection of phospholipid signals. Compared to unmodified TiO2 sub-micron particles, the DA-modified TiO2 monolith led to 10- to 30-fold increases in the signal-to-noise ratios of a number of compound peaks. The TiO2-DA monolith-assisted LDI MSI approach has higher selectivity and sensitivity for Lewis basic compounds, such as fatty acids, cholesterols, ceramides, diacylglycerols, and phosphatidylethanolamine, when analyzed in positive mode, than traditional MALDI MS. Using this new method, over 100 molecules, including amino acids, alkaloids, free fatty acids, peptides, and lipids, were localized in mouse brain sections. By comparing the presence and localization of those molecules in young and old mouse brains, the approach demonstrated good performance in the determination of aging-related neurochemical changes in the brain. PMID:28553535

  19. First-principle study of extrinsic defects in CuScO 2 and CuYO 2

    Science.gov (United States)

    Fang, Zhi-Jie; Shi, Li-Jie

    2008-05-01

    Using first-principles methods, we studied the extrinsic defects doping in transparent conducting oxides CuMO 2 (M dbnd Sc, Y). We chose Be, Mg, Ca, Si, Ge, Sn as extrinsic defects to substitute for M and Cu atoms. By systematically calculating the impurity formation energy and transition energy level, we find that Be is the most prominent extrinsic donor and Ca is the prominent extrinsic acceptor. In addition, we find that Mg atom substituting for Sc is the most prominent extrinsic acceptor in CuScO 2. Our calculation results are expected to be a guide for preparing n-type and p-type materials through extrinsic doping in CuMO 2 (M dbnd Sc,Y).

  20. Unraveling the resistive switching effect in ZnO/0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J.P.B., E-mail: josesilva@fisica.uminho.pt [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Vorokhta, M.; Dvořák, F. [Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Sekhar, K.C. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Department of Physics, School of Basic and Applied Science, Central University of Tamil Nadu, Thiruvarur 610 101 (India); Matolín, V. [Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Moreira, J. Agostinho [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Pereira, M.; Gomes, M.J.M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2017-04-01

    Highlights: • ZnO/0.5BZT-0.5BCT heterostructures exhibited resistive switching (RS) ratio ≥ 10 4. • Effect of oxygen pressure used in the deposition of ZnO on RS ratio is highlighted. • Determination of the Band alignment in ZnO/0.5BZT-0.5BCT heterojunctions from XPS. • Resistive Switching is explained based on charge coupling effect. - Abstract: This work reports the effect of partial oxygen pressure, used in the deposition of the ZnO layer, on the band alignment at ZnO – 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (0.5BZT-0.5BCT) interface and on the resistive switching (RS) behavior of pulsed laser deposited ZnO/0.5BZT-0.5BCT heterostructures. X-ray photoelectron spectroscopy (XPS) has been employed to measure the valence band offset and the conduction band offset of the ZnO/0.5BZT-0.5BCT heterojunctions. The valence and conduction band offsets of the ZnO/0.5BZT-0.5BCT heterostucture with ZnO deposited at 10{sup −2} mbar of partial oxygen pressure were found to be 0.27 and 0.80 eV, respectively. The RS effect in heterostructures is explained on the base of the charge coupling between the switchable polarization of ferroelectric layer and the non-switchable polarization of semiconductor layer. The heterostructure with ZnO deposited at 10{sup −2} mbar of partial oxygen pressure displays optimum RS characteristics, with a switching ratio ≥ 10{sup 4} and excellent retention and endurance characteristics. The optimum RS characteristics are attributed to a good interface quality with enough carrier concentration in ZnO, as evidenced by XPS.

  1. Physical conditions in CaFe interstellar clouds

    OpenAIRE

    Gnacinski, P.; Krogulec, M.

    2007-01-01

    Interstellar clouds that exhibit strong Ca I and Fe I lines were called CaFe clouds. The ionisation equilibrium equations were used to model the column densities of Ca II, Ca I, K I, Na I, Fe I and Ti II in CaFe clouds. The chemical composition of CaFe clouds is that of the Solar System and no depletion of elements onto dust grains is seen. The CaFe clouds have high electron densities n=1 cm^-3 that leads to high column densities of neutral Ca and Fe.

  2. Site distribution in heavily Sc3+-, Zr4+-, and Hf4+- substituted yttrium iron garnet

    Science.gov (United States)

    Balestrino, G.; Geller, S.

    1983-05-01

    Mössbauer spectra of yttrium iron garnet containing large amounts of Sc3+, Zr4+, and Hf4+ substituted for Fe3+ ions (the last two with electrostatic compensation by Ca2+ ions) confirm the conclusions deduced from 0-K spontaneous magnetization that the Zr4+ and Hf4+ ions prefer octahedral sites exclusively. Very small amounts of Sc3+ ions enter tetrahedral sites: For a total of one Sc3+ ion per formula unit, 0.03 is tetrahedral; for a total of 1.5 Sc3+ ions per formula unit, 0.09 is tetrahedral. These results imply that in the region of the ferrimagnetic ground state, i.e., to 0.72 Sc3+ ion per formula unit, at most 0.02 is tetrahedral, but it could be that there is none because of the coincidence of the 0-K dependence of the spontaneous magnetization on the composition of the Zr4+- and Sc3+-substituted yttrium iron garnets in that region. Thus the model given by Geller et al. for the magnetic behavior of substituted iron garnets is corroborated by these results.

  3. Cloning and expression of murine SC1, a gene product homologous to SPARC.

    Science.gov (United States)

    Soderling, J A; Reed, M J; Corsa, A; Sage, E H

    1997-06-01

    A number of cDNAs (SC1, QR1, and hevin) have been shown to be similar to SPARC (secreted protein acidic and rich in cysteine), a matricellular protein that regulates cell adhesion, cell cycle, and matrix assembly and remodeling. These proteins are 61-65% identical in the final 200 residues of their C-termini; their N-terminal sequences are related but more divergent. All have an overall acidic pl, with a follistatin-like region that is rich in cysteine, and a Ca+2 binding consensus sequence at the C-terminus. Using degenerate primers representing the most highly conserved region in SPARC, SC1, and QR1, we identified a 300-BP SC1 clone in a primary polymerase chain reaction (PCR) screen of a mouse brain cDNA library. This cDNA was used to obtain a full-length clone, which hybridized to a 2.8-KB RNA abundant in brain. Mouse SC1 displays a similarity of 70% to mouse SPARC at the amino acid level. Northern blot and RNAse protection assays revealed a 2.8-KB mRNA expressed at moderate levels (relative to brain) in mouse heart, adrenal gland, epididymis, and lung, and at low levels in kidney, eye, liver, spleen, submandibular gland, and testis. In contrast to SPARC, in situ hybridization showed expression of SC1 mRNA in the tunica media and/or adventitia of medium and large vessels; transcripts were not detected in capillaries, venules, or large lymphatics. The distribution of transcripts for SC1 was also different from that of SPARC in several organs, including adrenal gland, lung, heart, liver, and spleen. Moreover, SC1 mRNA was not evident in endothelium cultured from rat heart, bovine fetal and adult aorta, mouse aorta, human omentum, and bovine retina. Cultured smooth muscle cells and fibroblasts also failed to express SC1 mRNA. The absence of SC1 transcript in cultured cells indicates that the SC1 gene is potentially sensitive to regulatory factors in serum or to a three-dimensional architecture conferred by the extracellular matrix that is lacking in vitro. In

  4. Low modulus and bioactive Ti/α-TCP/Ti-mesh composite prepared by spark plasma sintering.

    Science.gov (United States)

    Guo, Yu; Tan, Yanni; Liu, Yong; Liu, Shifeng; Zhou, Rui; Tang, Hanchun

    2017-11-01

    A titanium mesh scaffold composite filled with Ti/α-TCP particles was prepared by spark plasma sintering (SPS). The microstructures and interfacial reactions of the composites were investigated by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The compressive strength and elastic modulus were also measured. In vitro bioactivity and biocompatibility was evaluated by using simulated body fluid and cells culture, respectively. After high temperature sintering, Ti oxides, TixPy and CaTiO3 were formed. The formation of Ti oxides and TixPy were resulted from the diffusion of O and P elements from α-TCP to Ti. CaTiO3 was the reaction product of Ti and α-TCP. The composite of 70Ti/α-TCP incorporated with Ti mesh showed a high compressive strength of 589MPa and a low compressive modulus of 30GPa. The bioactivity test showed the formation of a thick apatite layer on the composite and well-spread cells attachment. A good combination of mechanical properties and bioactivity indicated a high potential application of Ti/α-TCP/Ti-mesh composite for orthopedic implants. Copyright © 2017. Published by Elsevier B.V.

  5. Diagramas de equilibrio cuaternarios ZrO2-Al2O 3-SiO 2- (CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    OpenAIRE

    Pena, P.; Moya, J.S.; Batolomé, J. F.

    2011-01-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO2-Al2O3-SiO2(CaO, MgO, TiO2) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with r...

  6. Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    OpenAIRE

    Moya, J.S.; Bartolomé Gómez, José Florindo; Pena, Pilar

    2011-01-01

    En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el ...

  7. z206sc_video_observations

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents video observations from cruise Z206SC for the Santa Barbara Channel region and beyond in southern California. The vector data file is...

  8. Bandwidth challenge teams at SC2003 conference

    CERN Multimedia

    2003-01-01

    Results from the fourth annual High-Performance Bandwidth Challenge, held in conjunction with SC2003, the international conference on high-performance computing and networking which occurred last week in Phoenix, AZ (1 page).

  9. Sc3N and Sc2C2 encapsulated B40: Smarter than its carbon analogue

    Science.gov (United States)

    Shah, Esha V.; Roy, Debesh R.

    2016-10-01

    A detailed comparative investigation on the recently synthesised B40 and C40 along with their metal nitride (Sc3N)and carbide (Sc2C2) encapsulated endohedral fullerenes, is performed under density functional theory for the first time. The structures, electronic, thermodynamic and magnetic properties of all the considered compounds are explored in detail. The present study identifies borospherene (B40) and its encapsulated nitride (Sc3N@B40) and carbide (Sc2C2@B40) endohedral borofullerenes as the better candidates for future novel nano-applications compared to their carbon bucky ball analogues.

  10. ScPd2Al3 - New polymorphic phase in Al-Pd-Sc system

    Science.gov (United States)

    Pospíšil, Jiří; Haga, Yoshinori; Nakajima, Kunihisa; Ishikawa, Norito; Císařová, Ivana; Tateiwa, Naoyuki; Yamamoto, Etsuji; Yamamura, Tomoo

    2017-12-01

    We have discovered a new compound of the composition ScPd2Al3 crystallizing in unknown structure type. Moreover, ScPd2Al3 reveals polymorphism. We have found an orthorhombic crystal structure at room temperature and a high temperature cubic phase. The polymorphic phases are separated by a reversible first order transition at 1053 °C with a hysteresis of 19 °C. ScPd2Al3 exists as a very stable intermetallic phase just in the vicinity of the icosahedral quasicrystal Tsai-type i-phase Al54Pd30Sc16.

  11. Influence of Li2CO3 and V2O5 combined additions on the sintering and dielectric properties of Ca0.5Sr0.5TiO3 ceramics prepared from powders synthesized by sol-gel method

    Directory of Open Access Journals (Sweden)

    Nouara Lamrani

    2014-06-01

    Full Text Available In this work, we have studied the influence of lithium carbonate (Li2CO3 associated with the vanadium oxide (V2O5 on sintering and dielectrics properties of Ca0.5Sr0.5TiO3 ceramic materials obtained from nanopowder synthesized by sol-gel method. The nanopowder was obtained by controlled mixing of titanium butoxide dissolved in butanol-2 and acetic acid with a saturated aqueous solution of calcium acetate and strontium carbonate and subsequent drying of the formed gel at 80 °C and calcination at 1100 °C. The synthesized nanopowder was mixed with different amount of additives, and then uniaxally pressed and sintered in air atmosphere at temperature determined by dilatomertic measurements. The pure Ca0.5Sr0.5TiO3 sample obtained by this process required a sintering temperature around 1500 °C. The addition of Li2CO3 combined with V2O5 improved sinterability and caused a shift of dilatimeric shrinkage curve to much lower temperatures. Thus, dense ceramics (98% of theoretical density were obtained at sintering temperature ≤ 1300 °C. The effect of adding Li2CO3-V2O5 on the structure of ceramics and the dielectric properties is discussed and show that type I dielectric properties (linear variation of the permittivity are conserved, but with an increase of dielectric loss.

  12. Diagramas de equilibrio cuaternarios ZrO2-Al2O 3-SiO 2- (CaO, MgO, TiO2. Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    Directory of Open Access Journals (Sweden)

    Pena, P.

    2011-12-01

    Full Text Available In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO2-Al2O3-SiO2(CaO, MgO, TiO2 multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported.En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2. Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el caso de prótesis dentales sustituyendo a los materiales de circona parcialmente estabilizada con tierras raras.

  13. Dielectric and piezoelectric properties of lead-free Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9−x}Zr{sub 0.1}Cu{sub x}O{sub 3} ceramics synthesized by a hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Hunpratub, Sitchai [Material Science and Nanotechnology Programs, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Phokha, Sumalin [Department of Physics, Faculty of Science, Udon Thani Rajabhat University, Udon Thani 41000 (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Chindaprasirt, Prinya, E-mail: prinya@kku.ac.th [Sustainable Infrastructure Research and Development Center, Department of Civil Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2016-04-30

    Graphical abstract: Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9−x}Zr{sub 0.1}Cu{sub x}O{sub 3} (x = 0.2, 0.4, 0.6, 0.8 and 1%) ceramics are prepared from nanopowders synthesized using a hydrothermal method at low sintering temperature of 1300 °C for 3 h. The samples are dense microstructures investigated by scanning electron microscopy (SEM). The dielectric constants, ferroelectric hysteresis loops of Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9−x}Zr{sub 0.1}Cu{sub x}O{sub 3} ceramics are well character. - Highlights: • Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9−x}Zr{sub 0.1}Cu{sub x}O{sub 3} (x = 0.2, 0.4, 0.6, 0.8 and 1%) ceramics were prepared from nanopowders using a hydrothermal method. • The ceramic samples had high dielectric constant. • The ceramic samples showed a fine ferroelectric hysteresis loop. • The piezoelectric charge coefficient (d{sub 33}) of BCZTC ceramics was improved with Cu doping. - Abstract: Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9}Zr{sub 0.1−x}Cu{sub x}O{sub 3} (BCTZC) nanopowders were synthesized using a hydrothermal method after which they were pressed into discs and sintered in air at 1300 °C for 3 h to form ceramic samples. The phase and microstructure of the powder and ceramic samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results indicated that the ceramic samples exhibited a tetragonal structure and that CuO, BaZrO{sub 3} or CaTiO{sub 3} impurity phases, which had been present in the powder samples, were not observed. The average grain sizes in the ceramic samples were found to be 17.0, 16.1, 20.0, 18.1 and 19.6 μm for Cu mole fractions x of 0.002, 0.004, 0.006, 0.008 and 0.01, respectively. The dielectric constants, ferroelectric hysteresis loops and piezoelectric charge coefficients of the BCZTC ceramic samples were also investigated. Optimum values for the relative dielectric constant (ε′), tan δ and piezoelectric charge coefficient (d{sub 33}) of the samples were 3830, 0.03 and 306 p

  14. 33 CFR 80.707 - Cape Romain, SC to Sullivans Island, SC.

    Science.gov (United States)

    2010-07-01

    ... Island, SC. 80.707 Section 80.707 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... to Sullivans Island, SC. (a) A line drawn from the western extremity of Cape Romain 292° true to... southernmost extremity of Bull Island to the easternmost extremity of Capers Island. (d) A line formed by the...

  15. 33 CFR 80.712 - Morris Island, SC to Hilton Head Island, SC.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Morris Island, SC to Hilton Head Island, SC. 80.712 Section 80.712 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Seventh District § 80.712 Morris Island...

  16. 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.

  17. ORF Alignment: Ca19AnnotatedDec2004aaSeq [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available pothetical protein CaO19.1683 [Candida albicans SC5314] ... Length = 292 ... Query: 52 ... DLDGSSINQLDVWIEKLSKCEPLSETDVKKLCDMA...VEVLQFEENVQPVQVPVTICGDVHG 111 ... DLDGSSINQLDVWIEKLSKCEPLSETDVKKLCDMAVEVLQFEENVQPV...QVPVTICGDVHG Sbjct: 1 ... DLDGSSINQLDVWIEKLSKCEPLSETDVKKLCDMAVEVLQFEENVQPVQVPVTICGD

  18. Promises of cyclotron-produced 44Sc as a diagnostic match for trivalent β--emitters: in vitro and in vivo study of a 44Sc-DOTA-folate conjugate.

    Science.gov (United States)

    Müller, Cristina; Bunka, Maruta; Reber, Josefine; Fischer, Cindy; Zhernosekov, Konstantin; Türler, Andreas; Schibli, Roger

    2013-12-01

    In recent years, implementation of (68)Ga-radiometalated peptides for PET imaging of cancer has attracted the attention of clinicians. Herein, we propose the use of (44)Sc (half-life = 3.97 h, average β(+) energy [Eβ(+)av] = 632 keV) as a valuable alternative to (68)Ga (half-life = 68 min, Eβ(+)av = 830 keV) for imaging and dosimetry before (177)Lu-based radionuclide therapy. The aim of the study was the preclinical evaluation of a folate conjugate labeled with cyclotron-produced (44)Sc and its in vitro and in vivo comparison with the (177)Lu-labeled pendant. (44)Sc was produced via the (44)Ca(p,n)(44)Sc nuclear reaction at a cyclotron (17.6 ± 1.8 MeV, 50 μA, 30 min) using an enriched (44)Ca target (10 mg (44)CaCO3, 97.00%). Separation from the target material was performed by a semiautomated process using extraction chromatography and cation exchange chromatography. Radiolabeling of a DOTA-folate conjugate (cm09) was performed at 95°C within 10 min. The stability of (44)Sc-cm09 was tested in human plasma. (44)Sc-cm09 was investigated in vitro using folate receptor-positive KB tumor cells and in vivo by PET/CT imaging of tumor-bearing mice Under the given irradiation conditions, (44)Sc was obtained in a maximum yield of 350 MBq at high radionuclide purity (>99%). Semiautomated isolation of (44)Sc from (44)Ca targets allowed formulation of up to 300 MBq of (44)Sc in a volume of 200-400 μL of ammonium acetate/HCl solution (1 M, pH 3.5-4.0) within 10 min. Radiolabeling of cm09 was achieved with a radiochemical yield of greater than 96% at a specific activity of 5.2 MBq/nmol. In vitro, (44)Sc-cm09 was stable in human plasma over the whole time of investigation and showed folate receptor-specific binding to KB tumor cells. PET/CT images of mice injected with (44)Sc-cm09 allowed excellent visualization of tumor xenografts. Comparison of cm09 labeled with (44)Sc and (177)Lu revealed almost identical pharmacokinetics. This study presents a high-yield production and

  19. The temporoammonic input to the hippocampal CA1 region displays distinctly different synaptic plasticity compared to the Schaffer collateral input in vivo: significance for synaptic information processing

    Directory of Open Access Journals (Sweden)

    Ayla eAksoy Aksel

    2013-08-01

    Full Text Available In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic path (pp-CA1 synapse and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse. Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake animals, but these studies hint that information processing at this synapse might be distinct to processing at the Sc-CA1 synapse. Here, we characterized synaptic properties and synaptic plasticity at the pp-CA1 synapse of freely behaving adult rats. We established that field excitatory postsynaptic potentials at the pp-CA1 have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse. LTP (> 24h was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses. Low frequency stimulation evoked synaptic depression at Sc-CA1 synapses, but did not elicit LTD at pp-CA1 synapses unless the Schaffer collateral afferents to the CA1 region had been severed. Paired-pulse responses also showed significant differences. Our data suggest that synaptic plasticity at the pp-CA1 synapse is distinct from the Sc-CA1 synapse and that this may reflect its specific role in hippocampal information processing.

  20. Magnet measuring equipment of SC2

    CERN Multimedia

    1974-01-01

    Checking the positioning of the magnet measuring equipment installed between the poles of SC2. The steel structure in front of the magnet is designed to house the rotary condenser and to shield it from the stray magnetic field of the accelerator. On the left, Marinus van Gulik. (See Photo Archive 7402005 and Annual Report 1974, p. 44.)

  1. Final Scientific Report: DE-SC0008580

    Energy Technology Data Exchange (ETDEWEB)

    Seidler, Gerald T. [Univ. of Washington, Seattle, WA (United States)

    2017-03-16

    We report scientific, technical, and organizational accomplishments under DE-SC0008580. This includes 10 publications, 5 patent or provisional patent applications, beamtime with important results at both LCLS and APS, and new progress in understanding target design for x-ray heating experiments at x-ray heating facilities.

  2. The Synchrocyclotron (SC) in building 300

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    The red magnet of CERN's first accelerator, the Synchrocyclotron (SC), has occupied a large part of Hall 300 since it was installed in the late 1950s. The remaining part of the 300-square-metre building has been used as a storage room since the accelerator was shut down in 1990. Now a public exhibition will breathe new life into the hall.

  3. Magnet measuring equipment of SC2

    CERN Multimedia

    CERN PhotoLab

    1974-01-01

    Checking the positioning of the magnet measuring equipment installed between the poles of SC2. The steel structure in front of the magnet is designed to house the rotary condenser and to shield it from the stray magnetic field of the accelerator.

  4. Knowledge insufficient: the management of haemoglobin SC disease.

    Science.gov (United States)

    Pecker, Lydia H; Schaefer, Beverly A; Luchtman-Jones, Lori

    2017-02-01

    Although haemoglobin SC (HbSC) accounts for 30% of sickle cell disease (SCD) in the United States and United Kingdom, evidence-based guidelines for genotype specific management are lacking. The unique pathology of HbSC disease is complex, characterized by erythrocyte dehydration, intracellular sickling and increased blood viscosity. The evaluation and treatment of patients with HbSC is largely inferred from studies of SCD consisting mostly of haemoglobin SS (HbSS) patients. These studies are underpowered to allow definitive conclusions about HbSC. We review the pathophysiology of HbSC disease, including known and potential differences between HbSS and HbSC, and highlight knowledge gaps in HbSC disease management. Clinical and translational research is needed to develop targeted treatments and to validate management recommendations for efficacy, safety and impact on quality of life for people with HbSC. © 2016 John Wiley & Sons Ltd.

  5. Solar H2 evolution in water with modified diketopyrrolopyrrole dyes immobilised on molecular Co and Ni catalyst–TiO2 hybrids† †Electronic supplementary information (ESI) available: Experimental details, synthetic procedures, additional tables and figures. See DOI: 10.1039/c6sc05219c Click here for additional data file.

    Science.gov (United States)

    Warnan, Julien; Willkomm, Janina; Ng, Jamues N.; Godin, Robert; Prantl, Sebastian; Durrant, James R.

    2017-01-01

    A series of diketopyrrolopyrrole (DPP) dyes with a terminal phosphonic acid group for attachment to metal oxide surfaces were synthesised and the effect of side chain modification on their properties investigated. The organic photosensitisers feature strong visible light absorption (λ = 400 to 575 nm) and electrochemical and fluorescence studies revealed that the excited state of all dyes provides sufficient driving force for electron injection into the TiO2 conduction band. The performance of the DPP chromophores attached to TiO2 nanoparticles for photocatalytic H2 evolution with co-immobilised molecular Co and Ni catalysts was subsequently studied, resulting in solar fuel generation with a dye-sensitised semiconductor nanoparticle system suspended in water without precious metal components. The performance of the DPP dyes in photocatalysis did not only depend on electronic parameters, but also on properties of the side chain such as polarity, steric hinderance and hydrophobicity as well as the specific experimental conditions and the nature of the sacrificial electron donor. In an aqueous pH 4.5 ascorbic acid solution with a phosphonated DuBois-type Ni catalyst, a DPP-based turnover number (TONDPP) of up to 205 was obtained during UV-free simulated solar light irradiation (100 mW cm–2, AM 1.5G, λ > 420 nm) after 1 day. DPP-sensitised TiO2 nanoparticles were also successfully used in combination with a hydrogenase or platinum instead of the synthetic H2 evolution catalysts and the platinum-based system achieved a TONDPP of up to 2660, which significantly outperforms an analogous system using a phosphonated Ru tris(bipyridine) dye (TONRu = 431). Finally, transient absorption spectroscopy was performed to study interfacial recombination and dye regeneration kinetics revealing that the different performances of the DPP dyes are most likely dictated by the different regeneration efficiencies of the oxidised chromophores. PMID:28451376

  6. (44g)Sc production using a water target on a 13MeV cyclotron.

    Science.gov (United States)

    Hoehr, Cornelia; Oehlke, Elisabeth; Benard, Francois; Lee, Chris Jaeil; Hou, Xinchi; Badesso, Brian; Ferguson, Simon; Miao, Qing; Yang, Hua; Buckley, Ken; Hanemaayer, Victoire; Zeisler, Stefan; Ruth, Thomas; Celler, Anna; Schaffer, Paul

    2014-01-01

    Access to promising radiometals as isotopes for novel molecular imaging agents requires that they are routinely available and inexpensive to obtain. Proximity to a cyclotron center outfitted with solid target hardware, or to an isotope generator for the metal of interest is necessary, both of which can introduce significant hurdles in development of less common isotopes. Herein, we describe the production of ⁴⁴Sc (t1/2=3.97 h, Eavg,β⁺=1.47MeV, branching ratio=94.27%) in a solution target and an automated loading system which allows a quick turn-around between different radiometallic isotopes and therefore greatly improves their availability for tracer development. Experimental yields are compared to theoretical calculations. Solutions containing a high concentration (1.44-1.55g/mL) of natural-abundance calcium nitrate tetrahydrate (Ca(NO₃)2·4 H₂O) were irradiated on a 13MeV proton-beam cyclotron using a standard liquid target. (44g)Sc was produced via the ⁴⁴Ca(p,n)(44g)Sc reaction. (44g)Sc was produced for the first time in a solution target with yields sufficient for early radiochemical studies. Saturation yields of up to 4.6 ± 0.3 MBq/μA were achieved using 7.6 ± 0.3 μA proton beams for 60.0 ± 0.2 minutes (number of runs n=3). Experimental data and calculation results are in fair agreement. Scandium was isolated from the target mixture via solid-phase extraction with 88 ± 6% (n=5) efficiency and successfully used for radiolabelling experiments. The demonstration of the production of ⁴⁴Sc in a liquid target greatly improves its availability for tracer development. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Crystal structure and phase stability of AlSc in the near-equiatomic Al–Sc alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan; Huang, Li; Liang, Yongfeng [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083 (China); Ye, Feng, E-mail: yefeng@skl.ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083 (China); Lin, Junpin [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing 100083 (China); Shang, Shunli; Liu, Zikui [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2015-01-05

    Highlights: • Two lattice structures of equiatomic Al–Sc compounds are confirmed. • Al–Sc phase at Sc 50 at.% has a space group of Pbam. • Al–Sc phase at Sc 55 at.% has a space group of B2. • B2 AlSc is a metastable phase with Sc 50 at.%. • Lattice transition between two compounds is proposed under local thermal stress. - Abstract: Intermetallic compound AlSc is found in the equiatomic Al–Sc binary alloy. The present work indicates that the orthorhombic AlSc with the Au{sub 2}CuZn-type structure can be formed at 50 at.% Sc, while the CsCl-type (B2) AlSc will be formed at 55 at.% Sc. After annealing at 1100 °C, some orthorhombic AlSc grains transit to the B2 structure, and the annealing at lower temperatures leads to the disappearance of B2 phase, indicating that the B2 AlSc is also a metastable phase in the alloy at lower Sc content (<50 at.%). First-principle calculations at 0 K reveal that the orthorhombic AlSc is more stable than the B2 AlSc with the energy difference between them being 5.4 meV/atom. The fast transition between these two phases, which cannot be interpreted by the mechanism of atomic diffusion, was tentatively analyzed by the volume change based on the calculated atomic positions of these two phases.

  8. First-in-Human PET/CT Imaging of Metastatic Neuroendocrine Neoplasms with Cyclotron-Produced 44Sc-DOTATOC: A Proof-of-Concept Study.

    Science.gov (United States)

    Singh, Aviral; van der Meulen, Nicholas P; Müller, Cristina; Klette, Ingo; Kulkarni, Harshad R; Türler, Andreas; Schibli, Roger; Baum, Richard P

    2017-05-01

    44Sc is a promising positron emission tomography (PET) radionuclide (T1/2 = 4.04 hours, Eβ+average = 632 keV) and can be made available, using a cyclotron production route, in substantial quantities as a highly pure product. Herein, the authors report on a first-in-human PET/CT study using 44Sc-DOTATOC prepared with cyclotron-produced 44Sc. The production of 44Sc was carried out through the 44Ca(p,n)44Sc nuclear reaction at Paul Scherrer Institut, Switzerland. After separation, 44Sc was shipped to Zentralklinik Bad Berka, Germany, where radiolabeling was performed, yielding radiochemically pure 44Sc-DOTATOC. Two patients, currently followed up after peptide receptor radionuclide therapy of metastatic neuroendocrine neoplasms, participated in this proof-of-concept study. Blood sampling was performed before and after application of 44Sc-DOTATOC. PET/CT acquisitions, performed at different time points after injection of 44Sc-DOTATOC, allowed detection of even very small lesions on delayed scans. No clinical adverse effects were observed and the laboratory hematological, renal, and hepatic profiles remained unchanged. In this study, cyclotron-produced 44Sc was used in the clinic for the first time. It is attractive for theranostic application with 177Lu, 90Y, or 47Sc as therapeutic counterparts. 44Sc-based radiopharmaceuticals will be of particular value for PET facilities without radiopharmacy, to which they can be shipped from a centralized production site.

  9. Enhanced ferromagnetic properties of low temperature sintering LiZnTi ferrites with Li{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}–CaO–Al{sub 2}O{sub 3} glass addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Tingchuan, E-mail: simplezhou_8715@126.com; Zhang, Huaiwu, E-mail: hwzhang@uestc.edu.cn; Jia, Lijun; Liao, Yulong; Zhong, Zhiyong; Bai, Feiming; Su, Hua; Li, Jie; Jin, Lichuan; Liu, Cheng

    2015-01-25

    Highlights: • LiZnTi ferrites could be fired at ∼900 °C low temperature when the content of LBSCA glass is from 0.15 to 1.7 wt%. • Small amount of LBSCA glass is conducive to the densification and grain growth. • The ferromagnetic resonance (FMR) linewidth (ΔH) matches well with the basis of spin wave theory. • LiZnTi ferrites with optimum content of LBSCA glass have the potential applications in LTCC phase shifters. - Abstract: The effects of Li{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}–CaO–Al{sub 2}O{sub 3} (LBSCA) glass on the ferromagnetic properties of low-temperature sintered LiZnTi ferrites were systematically investigated. We characterized and analyzed the variation in microstructure, bulk density, porosity and ferromagnetic properties of the samples along with the changes of LBSCA glass content. The results revealed that the densification process of the samples was sensitive to the LBSCA glass content, and low LBSCA glass content was a precondition for sufficient densification, grain growth and ferromagnetic properties. The ferromagnetic resonance (FMR) linewidth (ΔH) was explained on the basis of spin wave theory of anisotropy and porosity broadening in polycrystalline materials. The sample sintered at 900 °C with 0.85 wt% LBSCA glass addition exhibits a saturation magnetization (m{sub s}) of 64.23 emu/g and a ferromagnetic resonance (FMR) linewidth (ΔH) of 191 Oe, suggesting that it is promising for LTCC phase shifters.

  10. Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03(Ti0.96Sn0.04O3 lead-free piezoelectric ceramics with high Curie temperature

    Directory of Open Access Journals (Sweden)

    Cheng-Che Tsai

    2016-12-01

    Full Text Available In this work, the process of two-stage modifications for (Ba0.97Ca0.03(Ti0.96Sn0.04-xHfxO3 (BCTS4-100xH100x ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC of about 112 °C, a piezoelectric charge constant (d33 of 313 pC/N, an electromechanical coupling factor (kp of 0.49, a mechanical quality factor (Qm of 122, and a remnant polarization (Pr of 19μC/cm2. In addition, the temperature stability of the resonant frequency (fr, kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ∼ 0.39, d33 ∼ 230 pC/N, Qm ∼ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03(Ti0.96Sn0.04O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.

  11. Pulsed laser deposition of La{sub 0.6}Ca{sub 0.4}Fe{sub 0.8}Ni{sub 0.2}O{sub 3−δ} thin films on SrTiO{sub 3}: Preparation, characterization and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, P.; Daneshmandi, S.; Salamati, H.; Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir

    2014-11-28

    In this study La{sub 0.6}Ca{sub 0.4}Fe{sub 0.8}Ni{sub 0.2}O{sub 3−δ} (LCFN) thin films are deposited on SrTiO{sub 3}(l00) (STO(l00)) and Si(100) substrates by pulsed laser deposition at oxygen pressure of 13.3, 26.7, 40 and 53.3 Pa. For LCFN/STO, X-ray diffraction and field emission scanning electron microscopy show film growth along (l00) direction. The electrical resistivity measurements reveal that PO{sub 2} = 40 Pa provides an optimum electrical properties with an electrical conductivity as high as 69 Scm{sup −1} and small polaron activation energy of 0.09 eV. It is attributed to increased films oxygen concentration and enhanced grains intimate contact. Also, by the measurement of electrical conductivity relaxation, chemical surface exchange coefficient of the film deposited at 40 Pa is calculated. Moreover, the effect of substrate type on the films electrical resistance is studied. - Highlights: • La{sub 0.6}Ca{sub 0.4}Fe{sub 0.8}Ni{sub 0.2}O{sub 3−δ} thin films were deposited by pulsed laser deposition. • The effect of oxygen pressure on films properties was studied. • Small polaron hopping was dominant mechanism in film electrical conductivity. • Comparing with Si, SrTiO{sub 3}(l00) substrates are better for electrical properties. • Electrical and morphological properties were optimum at 40 Pa oxygen pressure.

  12. Effect of Sb{sub 2}O{sub 3} on the electrical properties of Ba{sub 0.9}Ca{sub 0.1}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} ceramics fabricated using nanocrystals seed

    Energy Technology Data Exchange (ETDEWEB)

    Parjansri, P. [Rajamangala University of Technology Krungthep, Physics Division, Faculty of Science and Technology, Bangkok (Thailand); Intatha, U. [Mae Fah Luang University, School of Science, Chiang Rai (Thailand); Guo, R.; Bhalla, A.S. [University of Texas at San Antonio, Department of Electrical and Computer Engineering, Faculty of Engineering, San Antonio, TX (United States); Eitssayeam, S. [Chiang Mai University, Department of Physics and Materials Science, Faculty of Science, Chiang Mai (Thailand); Chiang Mai University, Materials Science Research Center, Faculty of Science, Chiang Mai (Thailand)

    2016-09-15

    This work was to investigate the effects of antimony oxide (Sb{sub 2}O{sub 3}) on the electrical properties of Ba{sub 0.9}Ca{sub 0.1}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (BCZT) ceramics and was prepared by adding 1 mol% of BCZT nanocrystals. The seed is nanocrystals of BCZT which was synthesized by the molten salt method. The ceramics powders were prepared by the mixed oxide method using BaCO{sub 3}, CaCO{sub 3}, ZrO{sub 2}, TiO{sub 2} as starting materials, and the BCZT seed was added as nanocrystal for induce phase transition. They were doped with x mol% Sb{sub 2}O{sub 3} (x = 0.0-0.5). Results indicated that all samples show pure perovskite phase. The Sb{sub 2}O{sub 3} enhanced the electrical properties of the ceramic systems. Excellent values of a dielectric constant (ε {sub r}) at room temperature (T{sub r}) were 4086 with sample of x = 0.5, and at Curie temperature (T{sub c}) was 15,485 for samples with x = 0.1. The highest remnant polarization (P{sub r}), piezoelectric charge coefficient (d{sub 33}), piezoelectric voltage coefficient (g{sub 33}), electromechanical coefficient for planar mode (k{sub p}) and thickness mode (k{sub t}) values were 6.3 μC/cm{sup 2}, 346 pC/N, 15.6 x 10{sup -3} Vm/N, 42 and 41 %, respectively, which were obtained for the sample of x = 0.2 mol% Sb. (orig.)

  13. Tuning the magnetic and transport properties of La0.8Ca0.2MnO3 films by Ba0.8Sr0.2TiO3 intercalated layers grown with polymer-assisted deposition

    Science.gov (United States)

    Pan, S. Y.; Shi, L.; Zhao, J. Y.; Xie, C. Z.; Zhou, S. M.; Li, Y.

    2017-06-01

    The La0.8Ca0.2MnO3/Ba0.8Sr0.2TiO3 (LCM/BST) bilayer films were epitaxially grown on SrTiO3 substrates with different orientations by the polymer-assisted deposition. The effects of annealing atmosphere and substrate orientation on the magnetic and transport properties of LCM/BST bilayer films have been investigated. A well crystallization quality of the films is confirmed by X-ray diffraction. Besides, the resistivity of the LCM/BST bilayer film shows high substrate-orientation dependent metal-insulator transition (MIT). However, with the decrease in temperature, in addition to the MIT at ˜220 K, an additional MIT emerges at a lower temperature and becomes robust, especially for the (111)-oriented LCM/BST bilayer film. Moreover, the additional MIT still exists when annealed in O2/air atmosphere but disappears in O2 atmosphere. Corroborated by the magnetic properties, it shows that the intercalated-layer technique of tuning the physical properties of transition-metal oxide films is achievable and more variable compared to the conventional way of chemical modification, which is beneficial to the development of multifunctional devices.

  14. Hemoglobin C, S-C, and E Diseases

    Science.gov (United States)

    ... more quickly than others, resulting in chronic anemia. Hemoglobin C disease Hemoglobin C disease occurs mostly in ... are a common complication of hemoglobin C disease. Hemoglobin S-C disease Hemoglobin S-C disease occurs in people ...

  15. LHCb Data Replication During SC3

    CERN Multimedia

    Smith, A

    2006-01-01

    LHCb's participation in LCG's Service Challenge 3 involves testing the bulk data transfer infrastructure developed to allow high bandwidth distribution of data across the grid in accordance with the computing model. To enable reliable bulk replication of data, LHCb's DIRAC system has been integrated with gLite's File Transfer Service middleware component to make use of dedicated network links between LHCb computing centres. DIRAC's Data Management tools previously allowed the replication, registration and deletion of files on the grid. For SC3 supplementary functionality has been added to allow bulk replication of data (using FTS) and efficient mass registration to the LFC replica catalog.Provisional performance results have shown that the system developed can meet the expected data replication rate required by the computing model in 2007. This paper details the experience and results of integration and utilisation of DIRAC with the SC3 transfer machinery.

  16. Spectroscopic study of the elusive globular cluster ESO452-SC11 and its surroundings

    Science.gov (United States)

    Koch, Andreas; Hansen, Camilla Juul; Kunder, Andrea

    2017-08-01

    Globular clusters (GCs) have long been recognized as being amongst the oldest objects in the Galaxy. As such, they have the potential of playing a pivotal role in deciphering the Milky Way's early history. Here we present the first spectroscopic study of the low-mass system ESO452-SC11 using the AAOmega multifibre spectrograph at medium resolution. Given the stellar sparsity of this object and the high degree of foreground contamination due to its location toward the Galactic bulge, very few details are known for this cluster - there is no consensus, for instance, about its age, metallicity, or its association with the disk or bulge. We identify five member candidates based on common radial velocity, calcium-triplet metallicity, and position within the GC. Using spectral synthesis, the measurement of accurate Fe-abundances from Fe-lines, and abundances of several α-, Fe-peak, and neutron-capture elements (Si, Ca, Ti,Cr, Co, Ni, Sr, and Eu) is carried out, albeit with large uncertainties. We find that two of the five cluster candidates are likely non-members, as they have deviating iron abundances and [α/Fe] ratios. The cluster mean heliocentric velocity is 19 ± 2 km s-1 with a velocity dispersion of 2.8 ± 3.4 km s-1, a low value in line with its sparse nature and low mass. The mean Fe-abundance from spectral fitting is -0.88 ± 0.03 dex, where the spread is driven by observational errors. Furthermore, the α-elements of the GC candidates are marginally lower than expected for the bulge at similar metallicities. As spectra of hundreds of stars were collected in a 2-degree field centered on ESO452-SC11, a detailed abundance study of the surrounding field was also enabled. The majority of the non-members have slightly higher [α/Fe] ratios, in line with the typical nearby bulge population. A subset of the spectra with measured Fe-peak abundance ratios shows a large scatter around solar values, albeit with large uncertainties. Furthermore, our study provides the

  17. Effect of A-Site Non-stoichiometry on Structure and Microwave Dielectric Properties of Ca x (Li0.36Nd0.36Bi0.14Na0.14)TiO3 Ceramics

    Science.gov (United States)

    Liu, Xiao; Yuan, Changlai; Luo, Fenghua; Liu, Xinyu; Zhen, Yuanlei; Liu, Fei; Chen, Guohua; Zhou, Changrong

    2018-01-01

    By adding a small amount of calcium to the starting composition, Li0.36Nd0.36Bi0.14Na0.14TiO3, oxygen vacancies are suppressed and, therefore, the microwave properties are enhanced. This study not only obtained a kind of ceramic with excellent microwave dielectric properties, ɛ r ˜ 160, Q × f ˜ 1300 GHz and τ f ˜ 10 ppm/°C, but also gives a way to optimize the compositions with various donor and acceptor dopants for better performance in microwave ceramics.

  18. Synthesis and microwave dielectric properties of Ca substituted ...

    Indian Academy of Sciences (India)

    Keywords. Patch antenna; theoretical density; phase; ceramics. Abstract. Microwave dielectric ceramics in Sr1-CaLa4Ti4.93Zr0.07O17 (0 ≤ ≤ 0.5) composition series were processed via a solid-state sintering rout. X-ray diffraction revealed single phase ceramics. Ca substitutions for Sr tuned f towards zero with ...

  19. Single chain Fab (scFab fragment

    Directory of Open Access Journals (Sweden)

    Brenneis Mariam

    2007-03-01

    Full Text Available Abstract Background The connection of the variable part of the heavy chain (VH and and the variable part of the light chain (VL by a peptide linker to form a consecutive polypeptide chain (single chain antibody, scFv was a breakthrough for the functional production of antibody fragments in Escherichia coli. Being double the size of fragment variable (Fv fragments and requiring assembly of two independent polypeptide chains, functional Fab fragments are usually produced with significantly lower yields in E. coli. An antibody design combining stability and assay compatibility of the fragment antigen binding (Fab with high level bacterial expression of single chain Fv fragments would be desirable. The desired antibody fragment should be both suitable for expression as soluble antibody in E. coli and antibody phage display. Results Here, we demonstrate that the introduction of a polypeptide linker between the fragment difficult (Fd and the light chain (LC, resulting in the formation of a single chain Fab fragment (scFab, can lead to improved production of functional molecules. We tested the impact of various linker designs and modifications of the constant regions on both phage display efficiency and the yield of soluble antibody fragments. A scFab variant without cysteins (scFabΔC connecting the constant part 1 of the heavy chain (CH1 and the constant part of the light chain (CL were best suited for phage display and production of soluble antibody fragments. Beside the expression system E. coli, the new antibody format was also expressed in Pichia pastoris. Monovalent and divalent fragments (DiFabodies as well as multimers were characterised. Conclusion A new antibody design offers the generation of bivalent Fab derivates for antibody phage display and production of soluble antibody fragments. This antibody format is of particular value for high throughput proteome binder generation projects, due to the avidity effect and the possible use of

  20. The SC gets ready for visitors

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Hall 300, which houses the Synchrocyclotron (SC), CERN’s first accelerator, is getting ready to host a brand-new exhibition. The site will be one of the stops on the new visit itineraries that will be inaugurated for the 2013 CERN Open Day.   The Synchrocyclotron through the years. Just as it did in the late 1950s, when the accelerator was first installed, the gigantic red structure of the Synchrocyclotron's magnet occupies a large part of the 300-square-metre hall. “We have completed the first phase of the project that will give the SC a new lease of life,” says Marco Silari, the project leader and a member of CERN’s Radiation Protection Group. “We have removed all the equipment that was not an integral part of the accelerator. The hall is now ready for the civil-engineering work that will precede the installation of the exhibition.” The SC was witness to a big part of the history of CERN. The accelerator produced ...

  1. sup 4 sup 4 Ti atom counting for nuclear astrophysics

    CERN Document Server

    Hui, S K; Berkovits, D; Boaretto, E; Ghelberg, S; Hass, M; Hershkowitz, A; Navon, E

    2000-01-01

    The nuclide sup 4 sup 4 Ti (T sub 1 sub / sub 2 =59.2 yr) has recently become an important asset to nuclear astrophysics through the measurement of its cosmic radioactivity, yielding significant information on fresh sup 4 sup 4 Ti nucleosynthesis in supernovae. We propose to use AMS to determine the production rate of sup 4 sup 4 Ti by the main channel believed to be responsible for sup 4 sup 4 Ti astrophysical production, namely sup 4 sup 0 Ca(alpha,gamma). A preliminary experiment conducted at the Koffler 14UD Pelletron accelerator demonstrates a sensitivity of 1x10 sup - sup 1 sup 4 for the sup 4 sup 4 Ti/Ti ratio. The AMS detection was performed using sup 4 sup 4 Ti sup - ions sputtered from a TiO sub 2 sample, reducing considerably the sup 4 sup 4 Ca isobaric interference. The present limit corresponds effectively to sup 4 sup 4 Ti production with resonance strength in the range 10-100 meV for a one-day sup 4 sup 0 Ca(alpha,gamma) activation. Several such resonances are known to be responsible for sup 4 ...

  2. Synthesis and characterization of reduced scandium halide containing one- and two-dimensional metal bonded arrays. [Sc--ScCl3; Cs3Sc2Cl9; CsScCl3

    Energy Technology Data Exchange (ETDEWEB)

    Poeppelmeier, K.R.

    1978-08-01

    The stabilization effect of metal-metal bond formation on reduced scandium compounds was studied. The binary compounds Sc/sub 7/Cl/sub 12/, Sc/sub 5/Cl/sub 8/, Sc/sub 7/Cl/sub 10/ and ScCl were prepared by high temperature techniques and were characterized by single crystal x-ray diffraction. The respective metal arrays in these compounds can be viewed as fragments of scandium metal ranging from discrete six atom metal cluster species (Sc(Sc/sub 6/Cl/sub 12/)), through intermediate single and double infinite chain configurations ((ScCl/sub 2/)(Sc/sub 4/Cl/sub 6/)) and ((ScCl/sub 2/)(Sc/sub 6/Cl/sub 8/)) to double metal close-packed sheets (ScCl). The halogen atoms effectively isolate the clusters, chains and sheets by bonding face, edge or exo positions on the metal arrays. The common occurrence of isolated scandium (III) ions emphasizes that a minimum number of bonding electrons is required to stabilize what are formally anionic metal arrays. The distribution of the reduction electrons in these anisotropic materials was studied by magnetic susceptibility, EPR and uv-X photoelectron spectroscopy. The ternary compounds studied were Cs/sub 3/Sc/sub 2/Cl/sub 9/ and CsScCl/sub 3/. The anion-bridged metal chain of the hexagonal perovskite structure was found to stabilize scandium (II). CsScCl/sub 3/ was found to be grossly nonstoichiometric on the transition metal site and the effects of the mixed valence character were studied between the single valence extremes Cs/sub 3/Sc/sub 2 + x/Cl/sub 9/; 0< x < 1.0.

  3. Electrical conductivity of Ca{sub 1-x}Sr{sub x}Ti{sub 0.65}Fe{sub 0.35}O{sub 3-{delta}}, x = 0, 0.5 and 1, polycrystalline compounds in the 300-500 K range

    Energy Technology Data Exchange (ETDEWEB)

    Muccillo, R., E-mail: muccillo@usp.br [Center of Science and Technology of Materials, Energy and Nuclear Research Institute, Travessa R 400, Cidade Universitaria, S. Paulo, SP 05508-900 (Brazil); Carmo, J.R. [Center of Science and Technology of Materials, Energy and Nuclear Research Institute, Travessa R 400, Cidade Universitaria, S. Paulo, SP 05508-900 (Brazil)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Fe-doped Sr and Ca titanates were synthesized by chemical and solid state reaction. Black-Right-Pointing-Pointer SPM images show striking differences in samples prepared by the two routes. Black-Right-Pointing-Pointer Impedance spectroscopy measurements show different electrical behaviors. Black-Right-Pointing-Pointer Correlations between the two macroscopic observations are shown. -- Abstract: Bulk and grain boundary electrical conductivity of oxygen deficient Ca{sub x}Sr{sub 1-x}Ti{sub 0.65}Fe{sub 0.35}O{sub 3-{delta}}, x = 0, 0.5 and 1.0, polycrystalline specimens were evaluated by impedance spectroscopy measurements in the 5 Hz-13 MHz frequency range from 300 to 500 K. The ceramic powders were synthesized by solid state reaction and by a chemical route, the polymeric precursor technique. The X-ray diffraction of the samples at room temperature shows the following perovskite crystalline structures: cubic for x = 0 and orthorhombic for x = 0.5 and 1.0. The impedance plots are composed of two semicircles ascribed to grains (bulk) and interfaces (grain boundaries) contributions. The impedance data show that sintered pellets using powders prepared by solid state synthesis present higher intergranular and intragranular resistivity values than pellets prepared by the chemical route. Observations of scanning probe microscopy topographic images of the surfaces of the sintered pellets show evident differences between the grain morphology of the pellets prepared with powders synthesized by the two routes.

  4. Exploration of R2XM2 (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge): Structural Motifs, the novel Compound Gd2AlGe2 and Analysis of the U3Si2 and Zr3Al2 Structure Types

    Energy Technology Data Exchange (ETDEWEB)

    McWhorter, Sean William [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    In the process of exploring and understanding the influence of crystal structure on the system of compounds with the composition Gd5(SixGe1-x)4 several new compounds were synthesized with different crystal structures, but similar structural features. In Gd5(SixGe1-x)4, the main feature of interest is the magnetocaloric effect (MCE), which allows the material to be useful in magnetic refrigeration applications. The MCE is based on the magnetic interactions of the Gd atoms in the crystal structure, which varies with x (the amount of Si in the compound). The crystal structure of Gd5(SixGe1-x)4 can be thought of as being formed from two 32434 nets of Gd atoms, with additional Gd atoms in the cubic voids and Si/Ge atoms in the trigonal prismatic voids. Attempts were made to substitute nonmagnetic atoms for magnetic Gd using In, Mg and Al. Gd2MgGe2 and Gd2InGe2 both possess the same 32434 nets of Gd atoms as Gd5(SixGe1-x)4, but these nets are connected differently, forming the Mo2FeB2 crystal structure. A search of the literature revealed that compounds with the composition R2XM2 (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge) crystallize in one of four crystal structures: the Mo2FeB2, Zr3Al2, Mn2AlB2 and W2CoB2 crystal structures. These crystal structures are described, and the relationships between them are highlighted. Gd2AlGe2 forms an entirely new crystal structure, and the details of its synthesis and characterization are given. Electronic structure calculations are performed to understand the nature of bonding in this compound and how

  5. The Microwave-Assisted Green Synthesis of TiC Powders

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2016-11-01

    Full Text Available Titanium carbide (TiC is an important engineering material and has found widespread applications. Currently, TiC is typically synthesized through carbothermal reduction, requiring a high temperature (ca. 1700–2300 °C and long reaction time (ca. 10–20 h, which is not eco-friendly. During a conventional reaction path, anatase TiO2 (A-TiO2 was first converted to rutile TiO2 (R-TiO2, which was subsequently reduced to TiC. Herein, we explored the synthesis of TiC powders with the assistance of microwave heating. In particular, we achieved the conversion of A-TiO2, which was more reactive than R-TiO2 for the carbothermal reduction, to TiC, which was directly due to quick microwave heating. As such, the carbothermal reduction started at a much lower temperature of ca. 1200 °C and finished within 30 min when reacting at 1400 °C, leading to significant energy saving. This study shows that microwave-assisted synthesis can be an effective and green process for preparing TiC powders, which is promising for future large-scale production. The influence of the reaction temperature, the reaction duration, and the carbon content on the synthesis of TiC powders was investigated.

  6. Martensitic Transformation in a β-Type Mg-Sc Alloy

    Science.gov (United States)

    Ogawa, Yukiko; Ando, Daisuke; Sutou, Yuji; Somekawa, Hidetoshi; Koike, Junichi

    2017-12-01

    Recently, we found that a Mg-Sc alloy with a bcc (β) phase exhibits superelasticity and a shape memory effect at low temperature. In this work, we examined the stress-induced and thermally induced martensitic transformation of the β-type Mg-Sc alloy and investigated the crystal structure of the thermally induced martensite phase based on in situ X-ray diffraction (XRD) measurements. The lattice constants of the martensite phase were calculated to be a = 0.3285 nm, b = 0.5544 nm, and c = 0.5223 nm when we assumed that the martensite phase has an orthorhombic structure (Cmcm). Based on the lattice correspondence between a bcc and an orthorhombic structures such as that in the case of β-Ti shape memory alloys, we estimated the transformation strain of the β Mg-Sc alloy. As a result, the transformation strains along the 001, 011, and 111 directions in the β phase were calculated to be + 5.7, + 8.8, and + 3.3%, respectively.

  7. Piezoelectric Ceramics of the (1 − x)Bi0.50Na0.50TiO3–xBa0.90Ca0.10TiO3 Lead-Free Solid Solution: Chemical Shift of the Morphotropic Phase Boundary, a Case Study for x = 0.06

    Science.gov (United States)

    Vivar-Ocampo, Rodrigo; Pardo, Lorena; Ávila, David; Morán, Emilio; González, Amador M.; Bucio, Lauro; Villafuerte-Castrejón, María-Elena

    2017-01-01

    Research and development of lead-free piezoelectric materials are still the hottest topics in the field of piezoelectricity. One of the most promising lead-free family of compounds to replace lead zirconate–titanate for actuators is that of Bi0.50Na0.50TiO3 (BNT) based solid solutions. The pseudo-binary (1 − x)Bi0.50Na0.50TiO3–xBa1 − yCayTiO3 system has been proposed for high temperature capacitors and not yet fully explored as piezoelectric material. In this work, the solid solution with x = 0.06 and y = 0.10 was obtained by two different synthesis routes: solid state and Pechini, aiming at using reduced temperatures, both in synthesis (<800 °C) and sintering (<1150 °C), while maintaining appropriated piezoelectric performance. Crystal structure, ceramic grain size, and morphology depend on the synthesis route and were analyzed by X-ray diffraction, together with scanning and transmission electron microscopy. The effects of processing and ceramic microstructure on the structural, dielectric, ferroelectric, and piezoelectric properties were discussed in terms of a shift of the Morphotropic Phase Boundary, chemically induced by the synthesis route. PMID:28773096

  8. TAGE-SC-L Branch Predictors Again

    OpenAIRE

    Seznec, André

    2016-01-01

    International audience; Outline In this study, we explore the performance limits of these TAGE-SC-L predictors for respectively 8Kbytes and 64Kbytes of storage budget. For a 8KB storage budget, our submitted predictor used most of its storage budget on the TAGE predictor, features a very small loop predictor LP and a neural statistical cor-rector exploiting global history path and very limited local history. The submitted 8Kbytes predictor achieves 4.991 MPKI on the CBP-5 train traces. With a...

  9. Cross sections of deuteron induced reactions on {sup 45}Sc up to 50 MeV: Experiments and comparison with theoretical codes

    Energy Technology Data Exchange (ETDEWEB)

    Hermanne, A., E-mail: aherman@vub.ac.be [Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), 1090 Brussel (Belgium); Adam Rebeles, R. [Cyclotron Laboratory, Vrije Universiteit Brussel (VUB), 1090 Brussel (Belgium); Tarkanyi, F.; Takacs, S. [Institute of Nuclear Research of the Hungarian Academy of Science, 4026 Debrecen (Hungary); Takacs, M.P. [Institute of Physics, University of Debrecen, 4010 Debrecen (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Science, 4026 Debrecen (Hungary); Institute of Experimental Physics, University of Debrecen, 4010 Debrecen (Hungary); Ignatyuk, A. [Institute of Physics and Power Engineering (IPPE), 246020 Obninsk (Russian Federation)

    2012-01-01

    Although Sc is not often used as alloying element in structural materials around charged particle accelerators, activation characteristics for possible production of longer lived Sc radioisotopes, used in biomedical applications and as tracers are needed. Cross sections for production of {sup 46,44m,44g,43}Sc and {sup 45,44}Ti were measured between the reaction thresholds and 50 MeV. A stacked foil irradiation followed by high resolution gamma spectroscopy was used. Reduced uncertainty was obtained by simultaneous remeasurement of the Al(d,x){sup 24}Na or {sup nat}Ni(d,x){sup 61}Cu monitor reaction over the whole energy range. A comparison with scarce experimental literature values and results of updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2010 online library) is discussed. Thick target yields for the medically relevant isotopes {sup 46,44m}Sc are presented and a discussion of production routes of the very long lived {sup 44}Ti (T{sub 1/2} = 60 y)({sup 44g}Sc generator) is made.

  10. BOOK REVIEW: Assessing Sc1 for GCSE

    Science.gov (United States)

    Reynolds, H.

    2000-01-01

    It is well known that investigations that `fit' the National Curriculum or examination board criteria are few in number. The fair testing emphasis means that pupils all over the country are finding out what affects the rate of a chemical reaction, the rate of photosynthesis or, in the case of Physics, the resistance of a wire. This book focuses on nine of the most common Sc1 investigations and how to prepare for them, manage and assess them. The author, a GCSE examiner, has turned his expertise into a handbook for improving Sc1 performance in the classroom. He has produced a book that would be extremely useful to both newly qualified teachers and experienced teachers. The first aim of the book, however, is to explain the requirements of Sc1. This is done comprehensively with examples of what the jargon means in practice. By breaking down the elements of planning, obtaining evidence, analysing evidence and evaluating, it is easy to see the subtleties of the mark descriptors. At first glance there seems to be little difference between the type of scientific knowledge needed for planning at level 6 and level 8. However, the level 8 statement specifies `detailed' scientific knowledge and understanding, which would mean a student should use equations from physics or symbolic chemical equations to support their arguments. One of the most useful sections in the book details the marking problems that can arise with some investigations. For example, in an investigation into electromagnets it is difficult for students to provide sufficient relevant scientific theory to satisfy the requirements of planning at level 6. One of the problems with Sc1 is that certain requirements, such as graph plotting, are difficult for many students. This book provides exercises that can be given to students to improve those skills. Each of the nine investigations is covered in great detail. Each investigation begins with an introduction detailing the rationale for choosing it, whether students

  11. Rich stoichiometries of stable Ca-Bi system: Structure prediction and superconductivity

    Science.gov (United States)

    Dong, Xu; Fan, Changzeng

    2015-03-01

    Using a variable-composition ab initio evolutionary algorithm implemented in the USPEX code, we have performed a systematic search for stable compounds in the Ca-Bi system at different pressures. In addition to the well-known tI12-Ca2Bi and oS12-CaBi2, a few more structures were found by our calculations, among which phase transitions were also predicted in Ca2Bi (tI12 --> oI12 --> hP6), Ca3Bi2 (hP5 --> mC20 --> aP5) and CaBi (tI2 --> tI8), as well as a new phase (Ca3Bi) with a cF4 structure. All the newly predicted structures can be both dynamically and thermodynamically stable with increasing pressure. The superconductive properties of cF4-CaBi3, tI2-CaBi and cF4-Ca3Bi were studied and the superconducting critical temperature Tc can be as high as 5.16, 2.27 and 5.25 K, respectively. Different superconductivity behaviors with pressure increasing have been observed by further investigations.

  12. Production of a {sup 44} Ti target and its cross section of thermal neutron capture; Producao de um alvo de {sup 44} Ti e sua secao de choque para captura de neutrons termicos

    Energy Technology Data Exchange (ETDEWEB)

    Ejnisman, R

    1993-12-31

    A study of the production of a {sup 44} Ti target was carried out aiming the determination of its thermal neutron capture cross-section. With this purpose, the cross-section of the reaction {sup 45} Sc(p,2 n) {sup 44} Ti was determined in the energies 16-, 18-, 20-22- and 45 MeV. The cross-section of the reactions (p,n) {sup 45} Ti, (p,pn) {sup 44m} Sc, (p,pn) {sup 44g} Sc and (p,p2n){sup 43} Sc were also measured. The results in the low energy region are in good agreement with a previous work by McGee et al. On the other hand, the cross-section at 45 MeV is different from McGee`s result and indicates the existence of an abnormal behavior of the excitation function at higher energies. Furthermore, a radiochemical separation method was developed in order to eliminate Sc from the {sup 44} Ti target which was irradiated with neutrons. It was possible to determine an upper limit for the cross-section of the reaction {sup 44} Ti (n, {gamma}) of 4 x 10{sup 3} b. At last, it is presented a discussion of the results obtained and their possible astrophysical implications. (author) 94 refs.

  13. Cyclotron Produced 44gSc from Natural Calcium

    Science.gov (United States)

    Severin, G.W.; Engle, J.W.; Valdovinos, H.F.; Barnhart, T.E.; Nickles, R.J.

    2012-01-01

    44gSc was produced by 16 MeV proton irradiation of unenriched calcium metal with radionuclidic purity greater than 95%. The thick target yield at saturation for 44gSc was 213 MBq/μA, dwarfing the yields of contaminants 43Sc,44mSc, 47Sc and 48Sc for practical bombardment times of 1–2 h. Scandium was isolated from the dissolved calcium target by filtration, and reconstituted in small volumes of dilute HCl. Reactions with the chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) indicated a reactivity of 54±14 Gbq/μmol at end-of-bombardment. PMID:22728844

  14. Exploring branch predictability limits with the MTAGE+SC predictor *

    OpenAIRE

    Seznec, André

    2016-01-01

    International audience; In the previous championship CBP-4, the winner of the unlimited storage track [5], poTAGE-SC was combining several TAGE based predictors using different forms of histories (local, global, and frequency), a COLT inspired [3] prediction combiner and a statistical corrector (SC) predictor [8, 10] fed with various forms of branch histories. With MTAGE-SC, we improve this predictor in two ways. First through incorporating new forms of branch histories, adding a new TAGE com...

  15. SC2: Secure Communication over Smart Cards

    DEFF Research Database (Denmark)

    Dragoni, Nicola; Lostal, Eduardo; Papini, Davide

    2012-01-01

    The Security-by-Contract (S×C) framework has recently been proposed to support software evolution in open multi-application smart cards. The key idea lies in the notion of contract, a specification of the security behavior of an application that must be compliant with the security policy...... of the card hosting the application. In this paper we address a key issue to realize the S×C idea, namely the outsourcing of the contractpolicy matching service to a Trusted Third Party (TTP). In particular, we present the design and implementation of (SC)2 (Secure Communication over Smart Cards), a system...... securing the communication between a smart card and the TTP which provides the S×C matching service....

  16. Final Scientific Report: DE-SC0002194

    Energy Technology Data Exchange (ETDEWEB)

    Seidler, Gerald [Univ. of Washington, Seattle, WA (United States)

    2017-04-07

    We provide the final scientific report for DE-SC0002194. During the term of this grant, 28 publications spanning a variety of topics were addressed under the rubric of advanced x-ray methods and their application to extreme conditions of time-resolution or x-ray intensities. Notable accomplishments include a new observation of XANES features associated with f-shell reconfiguration in lanthanides, size-dependent x-ray heating effects under XFEL illumination conditions, theoretical development of improved treatments of inelastic x-ray scattering for 'warm dense matter' conditions, and several new instrument develop efforts for atomic, molecular, and condensed phase studies in the lab and at major facility lightsources.

  17. The SC State NSF PAARE Program

    Science.gov (United States)

    Walter, Donald; Ajello, Marco; Brittain, Sean; Cash, Jennifer; Fogle, Bryan; Hartmann, Dieter; Ho, Shirley; Howell, Steve; King, Jeremy; Leising, Mark; Smith, Daniel

    2018-01-01

    We report on the activities of our NSF PAARE program during Year 3 of the project. Our partnership under this award includes South Carolina State University (a Historically Black College/University), Clemson University (a Ph.D. granting institution) and individual investigators at NASA Ames and elsewhere. Our partnership with the Citizen CATE Experiment and involvement in the total solar eclipse which passed through our campus on August 21, 2017, will be discussed. The PAARE project continues to strengthen our partnership with Clemson. We are close to completing a memorandum of agreement between the two institutions that will allow for the seamless transfer of an undergraduate from SC State to Clemson’s graduate program in physics and astronomy. Additionally, we have worked together under the Citizen CATE project and through other research activities. SC State is a member of the National Astronomy Consortium (NAC) and participates through its faculty and undergraduates, one of whom (Wesley Red) is reporting on his summer internship at this conference. We also served as the state coordinator for South Carolina for the Citizen CATE Experiment. The August 21st path of totality crossed through our campus and the campus of our partner Clemson University. Additional colleges, universities and citizen scientist groups partnered with us to provide 7 sites of coverage across South Carolina from the foothills of the Appalachian mountains to the Atlantic Ocean near the site of departure of the shadow from the continental U.S. Support for this work includes our NSF PAARE award AST-1358913 as well as resources and support provided by Clemson University and the National Optical Astronomy Observatory. CATE work has been supported by NASA SMD award NNX16AB92A to the National Solar Observatory. Additional details can be found at: http://physics.scsu.edu

  18. Multiferroic and magnetoelectric properties of Ba{sub 0.85}Ca{sub 0.15}Zr{sub 0.1}Ti{sub 0.9}O{sub 3}–CoFe{sub 2}O{sub 4} core–shell nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ajith S; Lekha, C.S. Chitra; Vivek, S. [Department of Physics, Central University of Kerala, Kasaragod 671314 (India); Saravanan, Venkata [Department of Physics, Central University of Tamil Nadu, Thiruvarur 610101 (India); Nandakumar, K. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Nair, Swapna S., E-mail: swapna.s.nair@gmail.com [Department of Physics, Central University of Kerala, Kasaragod 671314 (India)

    2016-11-15

    Lead-free magnetoelectric (ME) composites with remarkable ME coupling are required for the realization of eco-friendly multifunctional devices. This work demonstrates the ME properties of Ba{sub 0.85}Ca{sub 0.15}Zr{sub 0.1}Ti{sub 0.9}O{sub 3}–CoFe{sub 2}O{sub 4} (BCZT–CFO) core–shell composites synthesized via co-sol–gel technique. Room temperature ferroelectric and ferromagnetic characterization have shown that the samples are magnetic and ferroelectric along with an adequate magnetoelectric coupling of 12.15 mV/(cm Oe). The strong dependence of electric parameters on applied magnetic DC bias fields demonstrated in ferroelectric and magnetoelectric measurements provide a framework for the development of potential magnetoelectric devices. Also, the high sensitivity of magnetoelectric coupling towards the applied AC magnetic field can be used for its application in magnetoelectric sensors. - Highlights: • The magnetoelectric multiferroic BCZT–CFO nanocomposite is synthesized via sol–gel route. • The XRD measurements show no phases other than BCZT and CFO. • The microstructure analysis employing TEM indicates that the majority of particles formed are having core–shell structure. • The capacitance, resistance and ferroelectric polarization are magnetically tunable. • The composite showed a high magnetoelectric response.

  19. Electric-Field-Tunable Ferroelastic Control of Nonvolatile Resistivity and Ferromagnetic Switching in Multiferroic La0.67Ca0.33MnO3/[PbMg1/3Nb2/3O3] 0.7[PbTiO3]0.3 Heterostructures

    Science.gov (United States)

    Zheng, Ming; Zheng, Ren-Kui

    2016-04-01

    The electric-field-modulated nonvolatile resistivity and magnetization switching in elastically coupled La0.67Ca0.33MnO3 films grown on (111)-oriented 0.7 Pb (Mg1 /3Nb2 /3)O3-0.3 PbTiO3 substrates is achieved through the ferroelastic effect. By taking advantage of the 180° ferroelectric and non-180° ferroelastic domain switching, we identify that such changes in order parameters stem from domain-switching-induced strain rather than accumulation or depletion of charge carriers at the interface. Specifically, the strong correlation between the ferroelastic strain and the magnetic field is manifested not only by the strain-tunable magnetoresistance effect but also by the magnetically manipulated strain effect, which is essentially driven by the electronic phase separation. These findings present a potential strategy for elucidating the essential physics of the ferroelastic-strain effect and delivering prototype devices for energy-efficient and nonvolatile information storage.

  20. Final Report: DOE Award Number: DE-SC0006398, University of CA, San Diego

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer [Univ. of California, San Diego, CA (United States)

    2015-05-27

    The focus of the proposed research is to direct the assembly of single or binary nanoparticles into meso- or macroscale three-dimensional crystals of any desired configuration and crystallographic orientation without using prohibitively expensive lithographic processes. The epitaxial nucleation of defect-free, surface-bound bulk single crystals will revolutionize technologies for energy to generate new types of solar cells that yield maximum conversion efficiencies. It has been proposed that having a nanostructured bulk hetero-interface will enable efficient charge-carrier separations, similar to organic based heterojunction cells but with potential improvements, including thermal and long-term stability, tunability of energy levels, large adsorption coefficients and carrier multiplication. However, engineering such devices requires nanoscale control and ordering in both 2- and 3-dimensions over macroscopic areas and this has yet to be achieved. In Nature, bulk organic and inorganic materials are arranged into precise and ordered programmed assemblies through the sequestration of raw materials into confined spaces and association through highly specific non-covalent interactions between biomolecules. Using similar strategies, the proposed research will focus on confining metal and semiconductor nanocrystals to pre-determined surface patterns and controlling their arrangement through tunable, orthogonal biomolecular binding. Once a perfect two-dimensional seed layer has been constructed, successive layers of single nanocrystals will be nucleated epitaxially with long-range order and tunable crystallographic orientations. The proposed research exploits the ability of biomolecules to bind specific targets in a tunable, orthogonal, multivalent, and reversible manner to the arrangements of DNA-nanoparticle conjugates on chemically defined surfaces. Through careful balance of the attractive and repulsive forces between the particles, the array, and the outside surface, it is envisioned that single or mixed nanoparticles can be packed to adopt uniform crystal orientation in two and three dimensions from simple mixing and annealing of biomolecule-nanoparticle conjugates with biomolecule-stamped surfaces. To control the crystallographic alignment of each particle with its neighbors, the nanoparticles will be assembled using a mixture of non-covalent biomolecular interactions. To create solar cells in which layers of donor and acceptor nanocrystals that are not only oriented normal to the top and bottom electrodes but are also arranged in a checkerboard pattern, multicomponent nanocrystals (e.g. CdSe, CdTe) will be conjugated with biochemical linkers such that only interactions between the CdTe and CdSe promote particle packing within the array. The proposed research will: (1) elucidate the role of single and binary cooperative particle-DNA interactions in influencing nanoparticle crystallographic orientation in two and three dimensions; (2) understand how confinement of nanoparticles on patterned arrays of biomolecules and modification of the surrounding substrate can nucleate long-range order over macroscopic areas via predefined grain boundaries; and (3) synthesize and characterize DNA conjugated semiconductor nanocrystals and assemble them into 2- and 3-D binary superlattice arrays for photovoltaics.

  1. Electrochemical behavior of hydroxyapatite/TiN multi-layer coatings on Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Ju [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Jeong, Yong-Hoon [Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Brantley, William A. [Division of Restorative Science and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2014-12-01

    The electrochemical behavior of hydroxyapatite (HA) and titanium nitride (TiN) multi-layer coatings on Ti–Nb–Zr alloys was investigated by a variety of surface analytical methods. The HA/TiN layers were deposited using a magnetron sputtering system. The HA target was made of human tooth-ash sintered at 1300 °C for 1 h and had an average Ca/P ratio of 1.9. From X-ray diffraction patterns, the Ti–29Nb–5Zr alloy was composed entirely of equiaxed β-phase exhibiting the principal (110) reflection, and the coating exhibited the (111) and (200) reflections for TiN and the (112) and (202) reflections for HA. At the coating surface the HA films consisted of granular particles, and the surface roughness was 4.22 nm. The thickness of the coating layers increased in the order of HA/TiN (lowest), TiN, and HA (highest). Potentiodynamic polarization measurements revealed that the corrosion current density was the lowest, and the corrosion potential and polarization resistance the highest, when the Ti–29Nb–5Zr surface was covered by the HA/TiN film, compared to solely HA or TiN films. - Highlights: • HA/TiN films were deposited by magnetron sputtering on a Ti–29Nb–5Zr biomedical alloy. • The corrosion current density for the HA/TiN films was lower than that of the non-coated alloy. • The polarization resistance of the HA/TiN films was higher than that of the non-coated alloy.

  2. Hydride vapor phase epitaxy growth of GaN, InGaN, ScN, and ScAIN

    NARCIS (Netherlands)

    Bohnen, T.

    2010-01-01

    Chemical vapor deposition (CVD); hydride vapor phase epitaxy (HVPE); gallium nitride (GaN); indium gallium nitride (InGaN); scandium nitride (ScN); scandium aluminum nitride (ScAlN); semiconductors; thin films; nanowires; III nitrides; crystal growth - We studied the HVPE growth of different III

  3. Efficient sensitization of nanocrystalline TiO{sub 2} films with cyanine and merocyanine organic dyes

    Energy Technology Data Exchange (ETDEWEB)

    Sayama, Kazuhiro; Hara, Kohjiro; Arakawa, Hironori [National Inst. of Advanced Industrial Science and Technology (AIST), Photoreaction Control Research Center (PCRC), Tsukuba, Ibaraki (Japan); Tsukagoshi, Shingo; Mori, Tohru; Abe, Yoshimoto [Tokyo Science Univ., Faculty of Science and Technology, Noda, Chiba (Japan); Ohga, Yasuyo; Shinpou, Akira; Suga, Sadaharu [Hayashibara Biochemical Labs. Inc., Okayama (Japan)

    2003-10-15

    Various kinds of cyanine and merocyanine organic dyes having short anchoring groups as sensitizers on nanocrystalline TiO{sub 2} electrodes were investigated to promote the short-circuit photocurrent (J{sub sc}) and the solar light-to-power conversion efficiency ({eta}{sub sun}). The J{sub sc} and {eta}{sub sun} improved when the three different dyes (yellow and red cyanine dyes, and blue squarylium cyanine dye) were adsorbed simultaneously on a TiO2 electrode, as compared with the J{sub sc} and {eta}{sub sun} of the TiO2 electrodes adsorbed by each single dye. The maximum {eta}{sub sun} was 3.1 % (AM-l.5, 100 mW/cm{sup -2}). The J{sub sc} and {eta}{sub sun} were influenced by the solvents for the dye adsorption on the TiO{sub 2} electrode, and the efficiencies were improved by the addition of some cholic acids into the dye solution for adsorption. The electron transfer and/or the energy transfer from the red cyanine dye to the blue cyanine dye was observed on a SiO{sub 2} film using emission spectroscopy, suggesting a strong interaction between two dyes. The J-like aggregates of the blue cyanine dyes hardly showed sensitization efficiency. (Author)

  4. Fermi surface study of ScAu{sub 2}(Al, In) and ScPd{sub 2}(Sn, Pb) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, P. V. Sreenivasa; Kanchana, V., E-mail: kanchana@iith.ac.in [Department of Physics, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yeddumailaram-502205, Telangana (India); Vaitheeswaran, G. [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Hyderabad-500046 (India)

    2015-06-24

    A detailed study on the electronic structure and Fermi surface (FS) of superconducting Heusler compounds ScAu{sub 2}(Al, In) and ScPd{sub 2}(Sn, Pb) has been carried out using first principles electronic structure calculations. The spin orbit coupling is found to play a major role in understanding the band structure and FS. Analysis of the data shows the importance of spin orbit coupling effect in the above compounds. The bands which cross Fermi level (EF) are found to be dominated by the Sc d{sub t2g}-states. The calculated total density of states are in good agreement with the experimentally reported value for ScPd{sub 2}Sn. Under compression we find a change in the Fermi surface topology of ScPd{sub 2}Sn at V/V{sub 0} = 0.95 (pressure of≈15 GPa), which is explained using the band structure calculations.

  5. Synthesis and characterization of Zn-Ti layered double hydroxide intercalated with cinnamic acid for cosmetic application

    Science.gov (United States)

    Li, Yong; Tang, Liping; Ma, Xinxu; Wang, Xinrui; Zhou, Wei; Bai, Dongsheng

    2017-08-01

    The use of sunscreen is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently. In this work, an organic ultraviolet (UV) ray absorbent, cinnamic acid (CA) was intercalated into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. ZnTi-CA-LDH, a new type of host-guest UV-blocking material has been synthesized. Detailed structural and surface morphology of ZnTi-CA-LDH were characterized by XRD, FT-IR, SEM and TEM. ZnTi-CA-LDH exhibits a superior UV blocking ability compared to pure CA and ZnTi-CO3-LDH. The thermal stability of the intercalated ZnTi-CA-LDH was investigated by TG-DTA, which showed that the thermostability of CA was markedly enhanced after intercalation into ZnTi-CO3-LDH. The EPR data showed greatly decreased photocatalytic activity compared to common inorganic UV blocking agents TiO2 and ZnO. Furthermore, the sample was formulated in a sunscreen cream to study the matrix protective effect towards UV rays.

  6. Effects of calcium ion incorporation on bone healing of Ti6Al4V alloy implants in rabbit tibiae.

    Science.gov (United States)

    Park, Jin-Woo; Park, Kwang-Bum; Suh, Jo-Young

    2007-08-01

    The biocompatibility of calcium ion (Ca)-incorporated Ti6Al4V alloy implants, produced by hydrothermal treatment using a Ca-containing solution, was investigated. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, Auger electron spectroscopy, and stylus profilometry. The viability of MC3T3-E1 cells on Ca-incorporated machined Ti6Al4V surfaces with different oxide thicknesses was compared with that on untreated machined Ti6Al4V surfaces with MTT assay. The osteoconductivity of the Ca-incorporated Ti6Al4V implants was evaluated by removal torque testing and histomorphometric analysis after 6 weeks of implantation in rabbit tibiae. Our results show that hydrothermal treatment with a Ca-containing solution produced a crystalline CaTiO(3) layer on Ti6Al4V surfaces, and calcium ions were gradually incorporated throughout the oxide layer. After immersion in Hank's balanced salt solution, a considerable apatite deposition was observed on all surfaces of the Ca-incorporated samples. Significant increases in cell viability (pTi6Al4V implants compared with those for untreated Ti6Al4V implants.

  7. Visible light-operated saccharide-O{sub 2} biofuel cell based on the photosensitization of chlorophyll derivative on TiO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Amao, Yutaka; Takeuchi, Yumi [Department of Applied Chemistry, Oita University, Dannoharu 700, Oita 870-1192 (Japan)

    2008-06-15

    The visible light-operated saccharide-O{sub 2} biofuel cell consisting of zinc chlorin-e{sub 6} (ZnChl-e{sub 6}) adsorbed on nanocrystalline TiO{sub 2} layer coated onto optical transparent conductive glass electrode (OTE) as an anode, platinum-coated OTE as a cathode, and the fuel solution containing sucrose as a saccharide, invertase, glucose dehydrogenase (GDH) and NAD{sup +} is studied as a new type biofuel cell. The short-circuit photocurrent (I{sub SC}) and the open-circuit photovoltage (V{sub OC}) of this cell are 9.0 {mu}A cm{sup -2} and 415 mV, respectively. The peaks in the photocurrent action spectrum of this cell are observed at 400 and 800 nm and the incident photon-to-current efficiency (IPCE) values at 400 and 800 nm are estimated to be ca. 17.3% and 10.6%. Thus, a new type of visible light-operated saccharide-O{sub 2} biofuel cell with the visible and near IR photosensitization of ZnChl-e{sub 6} molecules on nanocrystalline TiO{sub 2} film electrode is accomplished. (author)

  8. Pascal-SC a computer language for scientific computation

    CERN Document Server

    Bohlender, Gerd; von Gudenberg, Jürgen Wolff; Rheinboldt, Werner; Siewiorek, Daniel

    1987-01-01

    Perspectives in Computing, Vol. 17: Pascal-SC: A Computer Language for Scientific Computation focuses on the application of Pascal-SC, a programming language developed as an extension of standard Pascal, in scientific computation. The publication first elaborates on the introduction to Pascal-SC, a review of standard Pascal, and real floating-point arithmetic. Discussions focus on optimal scalar product, standard functions, real expressions, program structure, simple extensions, real floating-point arithmetic, vector and matrix arithmetic, and dynamic arrays. The text then examines functions a

  9. SC-System of convergence theory and foundations

    Directory of Open Access Journals (Sweden)

    Sergio G. De los Cobos Silva

    2015-08-01

    Full Text Available In this paper a novel system of convergence (SC is presented as well as its fundamentals and computing experience. An implementation using a novel mono-objetive particle swarm optimization (PSO algorithm with three phases (PSO-3P: stabilization, generation with broad-ranging exploration and generation with in-depth exploration, is presented and tested in a diverse benchmark problems. Evidence shows that the three-phase PSO algoritm along with the SC criterion (SC-PSO-3Pcan converge to the global optimum in several difficult test functions for multiobjective optimization problems, constrained optimization problems and unconstrained optimization problems with 2 until 120,000 variables.

  10. Multiphase clock generators with controlled clock impulse width for programmable high order rotator SC FIR filters realized in 0.35 μm CMOS technology

    Science.gov (United States)

    Dlugosz, Rafal; Pawlowski, Pawel; Dabrowski, Adam

    2005-06-01

    Complexity of clock generator is one of the most important parameters in the design and optimization of switched-capacitor (SC) finite impulse response (FIR) filters. There are different SC FIR filter architectures. Some of them need a simple clock generator but the others require a quite complicated multiphase clock system. In the latter case an external clock system (i.e., outside the integrated circuit) is unrealistic because of a great number of the required external pins. We have implemented various SC FIR filter architectures together with complex internal clock generators in the CMOS 0.8 μm and 0.35 μm technologies. One of the most important problems in the design process was the optimization of waveforms and widths of the clock impulses. SC FIR filters are very sensitive to parameters of clock systems. Thus the clock generators must be designed very precisely. We demonstrate results of the design of the 64-phase clock generator for a programmable rotator SC FIR filter. In our approach the width of the clock impulses is controlled by two external signals. This is a very convenient solution, because optimization of the clock impulses, which was difficult in other approaches, is currently much easier. The internal clock generator area is ca. 0.15 mm2 in the CMOS 0.35 μm technology, i.e., only 7 % of the entire SC FIR filter chip area.

  11. Excitation functions for the radionuclide46Sc produced in the irradiation of 45Sc with deuterons and 6He

    Science.gov (United States)

    Skobelev, N. K.; Kulko, A. A.; Kroha, V.; Burjan, V.; Hons, Z.; Daniel, A. V.; Demekhina, N. A.; Kalpakchieva, R.; Kugler, A.; Mrázek, J.; Penionzhkevich, Yu E.; Piskoř, Š.; Šimečková, E.; Voskoboynik, E. I.

    2011-03-01

    Results of the measurements of the excitation function in the deuteron-induced reaction 45Sc(d, p)46Sc have been obtained at the energy of incident deuterons up to 11.7 MeV. In addition, data for the 45Sc(d, t)44Sc reaction were obtained. The experiments were performed using the variable energy cyclotron U-120M (NPI, Řež) and the Electrostatic Generator EG-5 (FLNP, JINR). The cross sections of the induced activities were measured using the stacked-foil technique. The measured excitation functions were similar to those observed for the 45Sc(6He, 5He*)46Sc reaction, studied at the accelerator complex for radioactive beams DRIBs (FLNR, JINR). The maximum probability of producing 46Sc was also found close to the Coulomb barriers of these reactions. The compilation of available experimental data, obtained at deuteron and 6He-energies near the Coulomb barrier, showed that the values of the cross sections at the maxima of the excitation functions obtained in (d, p) reactions and the reactions for one-neutron pickup from the 6He projectiles have a different Z-dependence.

  12. Precipitation in cold-rolled Al-Sc-Zr and Al-Mn-Sc-Zr alloys prepared by powder metallurgy

    KAUST Repository

    Vlach, Martin

    2013-12-01

    The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al3Sc and/or Al3(Sc,Zr) particles precipitated during extrusion at 350 C in the alloys studied. Additional precipitation of the Al3Sc and/or Al3(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 C. The precipitation of the Al6Mn- and/or Al 6(Mn,Fe) particles of a size ~ 1.0 μm at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al3Sc particles formation and/or coarsening and that of the Al6Mn and/or Al 6(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al3Sc-phase and the Al 6Mn-phase precipitation. © 2013 Elsevier Inc.

  13. Ti-in-Zircon Thermometer: Preliminary Results

    Science.gov (United States)

    Fu, B.; Cavosie, A. J.; Clechenko, C. C.; Fournelle, J.; Kita, N. T.; Lackey, J.; Page, F.; Wilde, S. A.; Valley, J. W.

    2005-12-01

    , permissive of low rutile activity. Peraluminous granites have lower whole-rock TiO2 content (0.02-0.21 wt.%) than metaluminous granites (0.54-0.91 wt.%), and both have similar zircon saturation temperatures (710-780°C). The low Ti content and apparent temperature in zircons from anorthosite and metagabbro (magmatic T = ca. 1000-1100°C) and the homogeneity of igneous zircon cores vs. metamorphic rims in metagabbro suggest that Ti content was reset during granulite-facies metamorphism (750°C, 1.0 Ga), in contrast to the current estimate of extremely low diffusivity of Ti in zircon. The Ti contents of >3.9 Ga Jack Hills detrital zircons are consistent with previously published data that were used to constrain magmatic temperature and thus the composition of unknown host rocks (W&H, 2005, Science 308:841). However, these values overlap those from both felsic and mafic rocks, and the Ti data are not sufficient to independently identify parent melt chemistry unless post-crystallization changes can be ruled out. The best evidence of pre-4 Ga evolved crust is provided by previously reported oxygen isotope ratios and felsic mineral inclusions in zircon (see Cavosie et al., 2005, EPSL 235:663).

  14. ^63Cu NQR relaxation in the p-type transparent conductor CuScO_2:Mg

    Science.gov (United States)

    Rossi, Vincent; Tate, Janet; Warren, William; Li, Jun; Sleight, Arthur

    2003-05-01

    Transparent conducting oxides with p-type conductivity are of interest as electronic complements to the more familiar n-type transparent conductors. This paper reports the first results of a study of carrier spin dynamics in p-type CuScO_2:Mg using ^63Cu nuclear spin-lattice relaxation measurements. Relaxation rates 1/T1 have been measured by nuclear quadrupole resonance (NQR) over the range 280 K to 400 K. The ^63Cu NQR frequency is found to be 28,135 ± 5 kHz at 300 K and to decrease linearly with temperature over the experimental range. The value of 1/T1 at 300 K is 130 ± 10 s-1. The rate is weakly dependent on temperature and increases by only about 15 % up to 400 K. This behavior contrasts sharply with results obtained previously(1. A. Rajabzadeh, J. Tate and W. Warren, Bull. Am. Phys. Soc. 48, 1009 (2003).) for the related material CuYO_2:Ca. In that material, relaxation rates for ^63Cu and ^65Cu were strongly temperature dependent, being approximately thermally-activated with activation energy 152 ± 10 meV. The nuclear relaxation properties of CuScO_2:Mg are suggestive of more conventional metallic transport in CuScO_2:Mg compared with CuYO_2:Ca.

  15. Structural, dielectric and piezoelectric study of Ca-, Zr-modified ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 5. Structural, dielectric and piezoelectric study of Ca-, Zr-modified BaTiO 3 lead-free ceramics. H MSOUNI A TACHAFINE M EL AATMANI D FASQUELLE J C CARRU M EL HAMMIOUI M RGUITI A ZEGZOUTI A OUTZOURHIT M DAOUD. Volume 40 Issue 5 ...

  16. Synthesis and electrophoretic deposition of hollow-TiO{sub 2} nanoparticles for dye sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Chava, Rama Krishna; Raj, Sudarsan; Yu, Yeon-Tae, E-mail: yeontae@jbnu.ac.kr

    2016-07-05

    Hollow TiO{sub 2} nanoparticles having ∼200 nm size are successfully prepared via selective etching of Au@TiO{sub 2} core shell nanoparticles which were synthesized by microwave hydrothermal growth. Electrophoretic deposition was successfully applied to make hollow TiO{sub 2} nanoparticles scattering layer for dye-sensitized solar cells (DSSCs) applications. The surface morphology and roughness features of deposited hollow TiO{sub 2} nanoparticles films are studied by field emission scanning electron microscope and atomic force microscope techniques respectively. The light scattering property of H–TiO{sub 2} makes it a promising candidate for use as the scattering layer in dye sensitized solar cells. Enhanced J{sub SC} values for the H–TiO{sub 2} based DSSCs were attributed to larger dye adsorption and stronger light scattering compared to the commercial TiO{sub 2} nanoparticle with a crystalline size of 20 nm. - Highlights: • Hollow TiO{sub 2} are produced by KCN etching of Au@TiO{sub 2} core–shell NPs. • EPD was successfully applied to make hollow TiO{sub 2} NPs film. • Compact, crack free and uniform hollow TiO{sub 2} NPs film was obtained by EPD. • Scattering layer of hollow TiO{sub 2} NPs was successfully introduced in DSS Cell.

  17. Design of SC walls and slabs for impulsive loading

    Energy Technology Data Exchange (ETDEWEB)

    Varma, Amit H. [Purdue Univ., West Lafayette, IN (United States)

    2015-11-11

    Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with a plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental and analytical investigations of the performance of SC walls subjected to far-field blast loads.

  18. Beta-decay studies of neutron-rich Sc-Cr nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gaudefroy, L.; Sorlin, O.; Donzaud, C.; Azaiez, F.; Bourgeois, C.; Chiste, V.; Guillemaud-Mueller, D.; Ibrahim, F.; Pougheon, F.; Stanoiu, M. [IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France); Angelique, J.C.; Grevy, S. [LPC, ISMRA, Caen Cedex (France); Dlouhy, Z.; Mrasek, J. [AS CR, Nuclear Physics Institute, Rez (Czech Republic); Kratz, K.-L.; Pfeiffer, B. [Universitaet Mainz, Institut fuer Kernchemie, Mainz (Germany); Lewitowicz, M.; Matea, I.; De Oliveira Santos, F.; Saint-Laurent, M.G. [GANIL, B.P. 5027, Caen Cedex (France); Lukyanov, S.M. [FLNR, JINR, Dubna, Moscow region (Russian Federation); Nowacki, F.; Penionzhkevich, Yu.-E. [Universite Louis Pasteur, IReS, IN2P3-CNRS, BP 28, Strasbourg Cedex (France)

    2005-01-01

    The neutron-rich nuclei{sup 57,58}{sub 21}Sc,{sup 58-60}{sub 22}Ti,{sup 60-63}{sub 23}V,{sup 62-66}{sub 24}Cr have been produced at Ganil via interactions of a 61.8A MeV {sup 76}Ge beam with a {sup 58}Ni target. Beta-decay studies have been performed using combined {beta}- and {gamma}-ray spectroscopy. Half-lives have been determined and {beta}-decay schemes are proposed for {sup 58}Ti, {sup 61}V and {sup 62}Cr. From these studies, new hints for the existence of {beta}-decaying isomers in {sup 60}V and in {sup 62}Mn are provided. These results are compared to shell model calculations. The role of the {pi}f{sub 7/2}- {nu}f{sub 5/2} proton-neutron interaction is examined through its influence on the lifetime values. (orig.)

  19. High-Ti type N-MORB parentage of basalts from the south Andaman ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    and CaO/TiO2 ratios classify these basalts as high-Ti type basalt. On the basis of these ratios and many discriminant functions and diagrams, it is suggested that the studied basalts, associated with Andaman ophiolite suite, were derived from magma similar to N-MORB and emplaced in the mid-oceanic ridge tectonic setting.

  20. Heteronuclear transition metal diatomics - The bonding and electronic structure of ScNi, YNi, ScPd, and YPd

    Science.gov (United States)

    Faegri, Knut, Jr.; Bauschlicher, Charles W., Jr.

    1991-01-01

    High quality ab initio calculations show that ScNi, YNi, ScPd, and YPd all have 2Sigma(+) ground states in agreement with electron spin resonance experiments. For ScNi and YNi, this is expected based on the lowest atomic asymptote. For ScPd and YPd, the lowest atomic asymptote would give the order of stability 2Delta greater than 2Pi equal to about 2Sigma(+), but the calculations show that mixing in of the excited asymptotes preferentially lowers the 2Sigma(+) state. The calculations show that the quartet states are about 20-30 kcal/mol above the ground state, and therefore probably do not contribute significantly to the unexpected g(vertical) values found in experiment. Calculations of excited states for YPd reveal some strong transitions that should be amenable to spectroscopic studies.

  1. Theoretical studies of the low-lying states of ScO, ScS, VO, and VS

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1986-01-01

    Bonding in the low-lying states of ScO, ScS, VO, and VS is theoretically studied. Excellent agreement is obtained with experimental spectroscopic constants for the low-lying states of ScO and VO. The results for VS and ScS show that the bonding in the oxides and sulfides is similar, but that the smaller electronegativity in S leads to a smaller ionic component in the bonding. The computed D0 of the sulfides are about 86 percent of the corresponding oxides, and the low-lying excited states are lower in the sulfides than in the corresponding oxides. The CPF method is shown to be an accurate and cost-effective method for obtaining reliable spectroscopic constants for these systems.

  2. Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

    Science.gov (United States)

    Saha, Bivas; Garbrecht, Magnus; Perez-Taborda, Jaime A.; Fawey, Mohammed H.; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Hultman, Lars; Sands, Timothy D.

    2017-06-01

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) × 1020 cm-3 range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 × 1020 cm-3 and a hole mobility of 21 cm2/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping.

  3. The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

    Science.gov (United States)

    Liu, Yi; Kim, Sun; McLeod, John A.; Li, Jun; Guo, Xiaoxuan; Sham, Tsun-Kong; Liu, Lijia

    2017-02-01

    The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

  4. Dielectric Spectroscopy of Pani-CaTiO3 Composites

    NARCIS (Netherlands)

    Parveen, Ameena; Kumar, Koppalkar Anil; Revanasidappa, M.; Ekhilikar, Shrikant; Prasad, M. V. N. Ambika

    2008-01-01

    The stability, processability and electrical and optical properties of polyaniline (PANI) have led to its being investigated for use in a wide variety of applications. Much of the initial work centered on the wide range of conductivity that can be achieved, covering some 20 orders of magnitude.

  5. XAFS spectroscopic study of Ti coordination in garnet

    Energy Technology Data Exchange (ETDEWEB)

    Ackerson, Michael R.; Tailby, Nicholas D.; Watson, E. Bruce

    2017-01-01

    Titanium can be incorporated either tetrahedrally (IVTi) or octahedrally (VITi) in most silicate minerals. Ti K-edge X-ray absorption fine structure (XAFS) spectroscopy enables observation of Ti coordination in minerals and melts. In this study, XAFS is used to determine the coordination of Ti in synthetic and natural garnets. Garnets grown synthetically at eclogite- and granulite-facies conditions can contain several wt% TiO2, most of which is incorporated as VITi. This observation aligns with major element trends in these garnets. In natural garnets grown at lower temperatures and pressures, on the other hand, Ti is observed to occupy both the octahedral and tetrahedral sites in garnet—in some cases Ti is almost entirely fourfold coordinated. Combined with previous research (see Ackerson et al. 2017, this issue) on substitution mechanisms for VITi, the results of this study demonstrate that Ti is incorporated on two crystallographic sites in garnet by at least three primary substitution mechanisms. In both natural and synthetic garnets, there is a discernible increase in VITi content in garnet with increasing temperature and pressure, suggesting a significant role for these two parameters in determining Ti solubility. However, a continuous increase in VITi with increasing grossular content also suggests that the Ca content of the garnet plays a critical role.

  6. A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

    Directory of Open Access Journals (Sweden)

    Azim Ataollahi Oshkour

    2014-01-01

    Full Text Available This study investigated the impact of calcium silicate (CS content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%. The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young’s modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements.

  7. Hydrothermal treatment for TiN as abrasion resistant dental implant coating and its fibroblast response

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xingling, E-mail: shixingling1985@hotmail.com [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan); Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); Xu, Lingli [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Munar, Melvin L.; Ishikawa, Kunio [Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan)

    2015-04-01

    Dental implant made of pure titanium (Ti) is prone to scratch and abrasion during routine oral hygiene procedures. This results an increase in surface roughness and therefore, facilitates the adhesion of bacteria. In severe cases, this could lead to peri-implantitis. To overcome this problem, surface modification of Ti is necessary to improve its abrasion resistance. Besides, a strong implant–gingiva interface should also be guaranteed to prevent the adhesion of bacteria. In this study, titanium nitride (TiN) coating was first prepared with gas nitriding to increase surface hardness of pure the substrate. Then, the TiN was hydrothermally treated in CaCl{sub 2} solution in order to improve its soft tissue biocompatibility. The effect of hydrothermal treatment temperature on surface properties of TiN was investigated and its biocompatibility was assessed in vitro using NIH3T3 fibroblast cell. It was determined that 120 °C was the critical temperature for the hydrothermal treatment condition. Treatment below 120 °C could incorporate Ca into TiN surface, oxidize TiN surface partially and then improve the wettability while preserving its morphology and hardness. Fibroblast cell attachment and proliferation were improved and cell spreading was enhanced on hydrothermally treated specimens compared with untreated ones. Improved wettability, Ca incorporation and negative surface due to interstitial N were believed to be the main reasons. Hydrothermal treatment is expected to make TiN a promising dental implant coating with excellent abrasion resistance and good soft tissue affinity. - Highlights: • Ca was incorporated into TiN surface while not sacrificing its hardness. • Interstitial N due to oxidation promoted Ca adsorption and cell adhesion. • Hydrothermal treatment makes TiN a promising coating for dental implant.

  8. Genetic interactions between the Golgi Ca2+/H+ exchanger Gdt1 and the plasma membrane calcium channel Cch1/Mid1 in the regulation of calcium homeostasis, stress response and virulence in Candida albicans.

    Science.gov (United States)

    Wang, Yanan; Wang, Junjun; Cheng, Jianqing; Xu, Dayong; Jiang, Linghuo

    2015-11-01

    The Golgi-localized Saccharomyces cerevisiae ScGdt1 is a member of the cation/Ca(2+) exchanger superfamily. We show here that Candida albicans CaGdt1 is the functional homolog of ScGdt1 in calcium sensitivity, and shows genetic interactions with CaCch1 or CaMid1 in response to ER stresses. In addition, similar to ScCCH1 and ScMID1, deletion of either CaCCH1 or CaMID1 leads to a growth sensitivity of cells to cold stress, which can be suppressed by deletion of CaGDT1. Furthermore, deletion of CaCCH1 leads to a severe delay in filamentation of C. albicans cells, and this defect is abolished by deletion of CaGDT1. In contrast, CaGDT1 does not show genetic interaction with CaMID1 in filamentation. Interestingly, C. albicans cells lacking both CaMID1 and CaGDT1 exhibit an intermediate virulence between C. albicans cells lacking CaCCH1 (non-virulent) and C. albicans cells lacking CaGDT1 (partially virulent), while C. albicans cells lacking both CaCCH1 and CaGDT1 are not virulent in a mouse model of systemic candidiasis. Therefore, CaGdt1 genetically interacts with the plasma membrane calcium channel, CaCch1/CaMid1, in the response of C. albicans cells to cold and ER stresses and antifungal drug challenge as well as in filamentation and virulence. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Final Technical Report for Award SC0008613

    Energy Technology Data Exchange (ETDEWEB)

    Knopf, Daniel A. [Stony Brook Univ., NY (United States)

    2017-04-05

    Discovering how aerosol particles, present in the atmosphere in sizes of a few nanometers to hundred micrometers, initiate ice crystal formation represents a great challenge. Atmospheric ice nucleation is important because ice crystals alter the radiative properties of clouds and thus climate, and impact precipitation and thus the hydrological cycle. The difficulty in predicting atmospheric ice formation is attributable at least in part, to the diversity of ice nucleation pathways, the physical and chemical complexity of the ice nucleating particles (INPs), and the relatively small numbers of INPs (compared with all other aerosol particles), sometimes less than one in 100000. These factors in turn makes constraining ice nucleation parameterizations for modeling applications challenging. The majority of airborne particles are known to be organic in nature or contain organic biogenic material. The presence of organic material adds to the complexity of the particles and therefore the predictability of ice nucleation events since the organic species can display different phase states, e.g. liquid or solid, in response to temperature and humidity. The award DE-SC0008613 to PI Prof. Daniel Knopf at Stony Brook University, “Relating the Chemical and Physical Properties of Aerosols to the Water Uptake and Ice Nucleation Potential of Particles Collected During the Carbonaceous Aerosols and Radiative Effects Study (CARES)”, allowed examination of laboratory generated aerosol particles and field-collected particles for their propensity to nucleate ice under typical tropospheric conditions and relate ice nucleation to the physicochemical properties of the particles including their morphology and chemical composition. This in turn allowed for development of ice nucleation parameterizations for implementation in cloud models. The award resulted in 10 peer-reviewed publications and more than 20 seminar and conference presentations. We demonstrated that the rate of immersion

  10. Effect of scandium on structure and hardening of Al–Ca eutectic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Belov, N.A., E-mail: nikolay-belov@yandex.ru [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); Naumova, E.A. [Bauman Moscow State Technical University, 5, 2 ul. Baumanskaya, Moscow, 105005 (Russian Federation); Alabin, A.N. [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation); Matveeva, I.A. [UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation)

    2015-10-15

    The phase composition, structure and hardening of alloys in the aluminium corner of the Al–Ca–Sc system were studied in the range up to 10% Ca and up to 1% S≿. The experimental study (optical, scanning and transmission electron microscopy with electron-microprobe analysis, differential thermal analysis and hardness measurements) was combined with Thermo-Calc software simulation for the optimization of the alloy composition. It was shown that only phases of the binary systems (Al{sub 4}Ca and Al{sub 3}Sc) might be in equilibrium with the aluminium solid solution. It was shown that the (Al) + Al{sub 4}Ca eutectic had a much finer structure as compared with the Al–Si eutectic, which suggests a possibility of reaching higher mechanical properties as compared to commercial alloys of the A356 type. The influence of the annealing temperature within the range up to 600 °C on the structure and hardness of the Al–Ca–Sc experimental alloys was studied. It was determined that the maximum hardening corresponded to the annealing at 300 °C, which was due to the precipitation of Al{sub 3}Sc nanoparticles with their further coarsening. With an example of an Al-7.6% Ca-0.3% Sc model experimental alloy, a principal possibility of manufacturing aluminium casting alloys based on the (Al) + Al{sub 4}Ca eutectic was demonstrated. Unlike commercial alloys of the A356 type, the model alloy does not require quenching, as hardening particles are formed in the course of annealing of casting. - Highlights: • Al–Ca–Sc phase diagram in aluminum corner. • Formation of Al{sub 3}Sc nanoparticles in eutectic (Al) + Al{sub 4}Ca during heating at 300–450 °C. • Hardening and thermal stability of proposed (Al–Ca–Sc) and commercial (Al–Si–Mg, 356 type) eutectic alloys.

  11. Spectroscopy of 50Sc and ab initio calculations of B (M 3 ) strengths

    Science.gov (United States)

    Garnsworthy, A. B.; Bowry, M.; Olaizola, B.; Holt, J. D.; Stroberg, S. R.; Cruz, S.; Georges, S.; Hackman, G.; MacLean, A. D.; Measures, J.; Patel, H. P.; Pearson, C. J.; Svensson, C. E.

    2017-10-01

    The GRIFFIN spectrometer at TRIUMF-ISAC has been used to study excited states and transitions in 50Sc following the β decay of 50Ca. Branching ratios were determined from the measured γ -ray intensities, and angular correlations of γ rays have been used to firmly assign the spins of excited states. The presence of an isomeric state that decays by an M 3 transition with a B (M 3 ) strength of 13.6(7) W.u. has been confirmed. We compare the first ab initio calculations of B (M 3 ) strengths in light- and medium-mass nuclei from the valence-space in-medium similarity renormalization group approach, using consistently derived effective Hamiltonians and effective M 3 operator. The experimental data are well reproduced for isoscalar M 3 transitions when using bare g factors, but the strength of isovector M 3 transitions are found to be underestimated by an order of magnitude.

  12. Piezoelectric coefficients and spontaneous polarization of ScAlN.

    Science.gov (United States)

    Caro, Miguel A; Zhang, Siyuan; Riekkinen, Tommi; Ylilammi, Markku; Moram, Michelle A; Lopez-Acevedo, Olga; Molarius, Jyrki; Laurila, Tomi

    2015-06-24

    We present a computational study of spontaneous polarization and piezoelectricity in Sc(x)Al(1-x)N alloys in the compositional range from x = 0 to x = 0.5, obtained in the context of density functional theory and the Berry-phase theory of electric polarization using large periodic supercells. We report composition-dependent values of piezoelectric coefficients e(ij), piezoelectric moduli d(ij) and elastic constants C(ij). The theoretical findings are complemented with experimental measurement of e33 for a series of sputtered ScAlN films carried out with a piezoelectric resonator. The rapid increase with Sc content of the piezoelectric response reported in previous studies is confirmed for the available data. A detailed description of the full methodology required to calculate the piezoelectric properties of ScAlN, with application to other complex alloys, is presented. In particular, we find that the large amount of internal strain present in ScAlN and its intricate relation with electric polarization make configurational sampling and the use of large supercells at different compositions necessary in order to accurately derive the piezoelectric response of the material.

  13. ORF Alignment: Ca19AnnotatedDec2004aaSeq [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available Ca19AnnotatedDec2004aaSeq orf19.6369; >1tqmA 7 276 41 325 3e-71 ... gb|EAK97210.1| hy....13726 [Candida ... albicans SC5314] ... Length = 285 ... Query: 8 ... MRYLTSDDFRVLQAIELGSRNHELVPTQM...IHSIGGLKSPSATNRAIGDIAKLKLISRLRN 67 ... MRYLTSDDFRVLQAIELGSRNHELVPTQMIHSIG...GLKSPSATNRAIGDIAKLKLISRLRN Sbjct: 1 ... MRYLTSDDFRVLQAIELGSRNHELVPTQMIHSIGGLKSPSATNRAIGDIAKLKLISRLRN 60 ... Query

  14. ORF Alignment: Ca19AnnotatedDec2004aaSeq [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available Ca19AnnotatedDec2004aaSeq orf19.1711; >1iq3A 15 104 3 93 2e-21 ... gb|EAL03000.1| potential EF Hand endocytosi...s protein End3p [Candida albicans ... SC5314] gb|EAL02871.1| potential EF Hand endocytosis

  15. ORF Alignment: Ca19AnnotatedDec2004aaSeq [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available rk protein [Candida albicans SC5314] ... gb|EAK91583.1| potential signalling network... Ca19AnnotatedDec2004aaSeq orf19.3505; >1unqA 2 108 330 443 2e-04 ... gb|EAK91599.1| potential signalling netwo

  16. Mass Measurement of 56Sc Reveals a Small A = 56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust.

    Science.gov (United States)

    Meisel, Z; George, S; Ahn, S; Bazin, D; Brown, B A; Browne, J; Carpino, J F; Chung, H; Cole, A L; Cyburt, R H; Estradé, A; Famiano, M; Gade, A; Langer, C; Matoš, M; Mittig, W; Montes, F; Morrissey, D J; Pereira, J; Schatz, H; Schatz, J; Scott, M; Shapira, D; Smith, K; Stevens, J; Tan, W; Tarasov, O; Towers, S; Wimmer, K; Winkelbauer, J R; Yurkon, J; Zegers, R G T

    2015-10-16

    We present the mass excesses of (52-57)Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85(59)((-54)(+0))  MeV and -21.0(1.3)  MeV, respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A = 56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A≈56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.

  17. Mass Measurement of 56Sc Reveals a Small A =56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

    Science.gov (United States)

    Meisel, Z.; George, S.; Ahn, S.; Bazin, D.; Brown, B. A.; Browne, J.; Carpino, J. F.; Chung, H.; Cole, A. L.; Cyburt, R. H.; Estradé, A.; Famiano, M.; Gade, A.; Langer, C.; Matoš, M.; Mittig, W.; Montes, F.; Morrissey, D. J.; Pereira, J.; Schatz, H.; Schatz, J.; Scott, M.; Shapira, D.; Smith, K.; Stevens, J.; Tan, W.; Tarasov, O.; Towers, S.; Wimmer, K.; Winkelbauer, J. R.; Yurkon, J.; Zegers, R. G. T.

    2015-10-01

    We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85 (59 )(-54+0) MeV and -21.0 (1.3 ) MeV , respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A =56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A ≈56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.

  18. Transport of one SC coil through the village of Meyrin

    CERN Multimedia

    1956-01-01

    In 1952, before CERN was officially founded, two accelerator projects were launched: one for an innovative accelerator to operate at an energy level unequalled at the time, the other for a more standard machine, a Synchro-Cyclotron (SC) to operate at 600 MeV. Design work on the SC was started in 1952 and carried out by teams scattered throughout Europe. Once construction began in 1954, CERN had to arrange road transport for the first of what has since been a long series of spectacular component deliveries, such as those of the machine's two magnetic coils each weighing 60 tonnes and measuring 7.2 metres in diameter. Above, one of them is seen passing through the village of Meyrin. The SC was commissioned in 1957 and was operational for 34 years!

  19. Experience with OpenMP for MADX-SC

    Energy Technology Data Exchange (ETDEWEB)

    D' Imperio, Nicholas [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Montag, Christophe [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Yu, Kwangmin [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Kapin, Valery [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); McIntosh, Eric [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Renshall, Harry [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Schmidt, Frank [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-07-01

    MADX-SC allows the treatment of frozen space charge using beam-beam elements in a thin lattice, i.e. one can take advantage of the standard set-up of MAD-X lattices without the need for specialized codes for the space-charge (SC) evaluation. The idea is to simulate over many turns without the problem of noise as in the PIC SC codes. For the examples under study, like the PS and RHIC, it would be desirable to simulate up to 1 million turns or more. To this end one had to make an effort to optimize the scalar speed and, most importantly, get a speed-up of approximately a factor of 5 using OpenMP.

  20. Experience with OpenMP 1 for MADX-SC

    CERN Document Server

    D’Imperio, N; Yu, K; Kapin, V; McIntosh, E; Renshall, H; Schmidt, F

    2014-01-01

    MADX-SC [1–3] allows the treatment of frozen space charge using beam-beam elements in a thin lattice, i.e. one can take advantage of the standard set-up of MAD-X [4] lattices without the need for specialized codes for the space-charge (SC) evaluation. The idea is to simulate over many turns without the problem of noise as in the PIC 1 SC codes. For the examples under study, like the PS and RHIC, it would be desirable to simulate up to 1 million turns or more. To this end one had to make an effort to optimize the scalar speed and, most importantly, get a speed-up of approximately a factor of 5 using OpenMP [5].

  1. Paracyclophane functionalized with Sc and Li for hydrogen storage

    Science.gov (United States)

    Sathe, Rohit Y.; Dhilip Kumar, T. J.

    2018-01-01

    Li and Sc metals functionalized on the delocalized π -electrons of benzene rings in [2,2]paracyclophane structure are studied for hydrogen storage efficiency by using the M06 DFT functional with 6-311G(d,p) basis set. It is found that Sc and Li functionalized [2,2]paracyclophane complexes can hold up to 10 H2 molecules and 8 H2 molecules by Kubas-Niu-Jena interaction and charge polarization mechanism with hydrogen weight percentage of 11.4 and 13.5, respectively. Molecular dynamics simulation at various temperatures showed appreciable thermal stability while the chemical potential calculation at room temperature reveals that Sc functionalized [2,2]paracyclophane system will be a promising hydrogen storage material.

  2. INTRACELLULAR Ca2+ HOMEOSTASIS

    Directory of Open Access Journals (Sweden)

    Shahdevi Nandar Kurniawan

    2015-01-01

    Full Text Available Ca2+ signaling functions to regulate many cellular processes. Dynamics of Ca2+ signaling or homeostasis is regulated by the interaction between ON and OFF reactions that control Ca2+ flux in both the plasma membrane and internal organelles such as the endoplasmic reticulum (ER and mitochondria. External stimuli activate the ON reactions, which include Ca2+ into the cytoplasm either through channels in the plasma membrane or from internal storage like in ER. Most of the cells utilize both channels/sources, butthere area few cells using an external or internal source to control certain processes. Most of the Ca2+ entering the cytoplasm adsorbed to the buffer, while a smaller part activate effect or to stimulate cellular processes. Reaction OFF is pumping of cytoplasmic Ca2+ using a combination mechanism of mitochondrial and others. Changes in Ca2+ signal has been detected in various tissues isolated from animals induced into diabetes as well as patients with diabetes. Ca2+ signal interference is also found in sensory neurons of experimental animals with diabetes. Ca2+ signaling is one of the main signaling systems in the cell.

  3. Self-propagating high-temperature synthesis of Ce-bearing zirconolite-rich minerals using Ca(NO{sub 3}){sub 2} as the oxidant

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kuibao, E-mail: xiaobao320@163.com [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); National Defense Key Discipline Lab of Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010 (China); Wen, Guanjun; Yin, Dan [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Haibin, E-mail: hbzhang@imr.ac.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-12-15

    Synroc is recognized as the second generation waste form for the immobilization of high-level radioactive waste (HLW). Zirconolite-rich (CaZrTi{sub 2}O{sub 7}) Synroc minerals were attempted by self-propagating high-temperature synthesis (SHS) using Fe{sub 2}O{sub 3}, CrO{sub 3}, Ca(NO{sub 3}){sub 2} as the oxidants and Ti as the reductant. All designed reactions were ignited and sustained using Ca(NO{sub 3}){sub 2} as the oxidant, and zirconolite-rich ceramic matrices were successfully prepared with pyrochlore (Ca{sub 2}Ti{sub 2}O{sub 6}), perovskite (CaTiO{sub 3}) and rutile (TiO{sub 2}) as the minor phases. The sample CN-4, which was designed using Ca(NO{sub 3}){sub 2} as the oxidant with TiO{sub 2}/Ti ratio of 7:9, was readily solidified with density of 4.62 g/cm{sup 3} and Vickers hardness of 1052 HV. CeO{sub 2} was successfully stabilized by the CN-4 sample with resultant phase constituent of 2M-CaZrTi{sub 2}O{sub 7} and CaTiO{sub 3}. - Highlights: • Zirconolite was synthesized by SHS using Ca(NO{sub 3}){sub 2} as the oxidant. • T{sub ad} was calculated to evaluate the sustainability of SHS with Ca(NO{sub 3}){sub 2} oxidant. • The selected sample was readily solidified with density of 4.62 g/cm{sup 3}. • CeO{sub 2} was successfully immobilized into the SHS-ed Synroc.

  4. A mixture of anatase and rutile TiO2 nanoparticles induces histamine secretion in mast cells

    Directory of Open Access Journals (Sweden)

    Chen Eric Y

    2012-01-01

    Full Text Available Abstract Background Histamine released from mast cells, through complex interactions involving the binding of IgE to FcεRI receptors and the subsequent intracellular Ca2+ signaling, can mediate many allergic/inflammatory responses. The possibility of titanium dioxide nanoparticles (TiO2 NPs, a nanomaterial pervasively used in nanotechnology and pharmaceutical industries, to directly induce histamine secretion without prior allergen sensitization has remained uncertain. Results TiO2 NP exposure increased both histamine secretion and cytosolic Ca2+ concentration ([Ca2+]C in a dose dependent manner in rat RBL-2H3 mast cells. The increase in intracellular Ca2+ levels resulted primarily from an extracellular Ca2+ influx via membrane L-type Ca2+ channels. Unspecific Ca2+ entry via TiO2 NP-instigated membrane disruption was demonstrated with the intracellular leakage of a fluorescent calcein dye. Oxidative stress induced by TiO2 NPs also contributed to cytosolic Ca2+ signaling. The PLC-IP3-IP3 receptor pathways and endoplasmic reticulum (ER were responsible for the sustained elevation of [Ca2+]C and histamine secretion. Conclusion Our data suggests that systemic circulation of NPs may prompt histamine release at different locales causing abnormal inflammatory diseases. This study provides a novel mechanistic link between environmental TiO2 NP exposure and allergen-independent histamine release that can exacerbate manifestations of multiple allergic responses.

  5. Low-{beta} SC linacs : past, present, and future.

    Energy Technology Data Exchange (ETDEWEB)

    Bollinger, L. M.

    1998-11-18

    This paper is a general review of superconducting low-{beta} technology and applications from its beginning in 1969 into the near-term future. The emphasis is on studies of accelerating resonators and on SC linacs that boost the energy of heavy-ion beams from tandem electrostatic accelerators used for nuclear-physics research. Other topics are positive-ion SC injectors to replace tandems and the need for accelerating structures with {beta} outside of the present proven range, 0.008 < {beta} < 0.2.

  6. Thermoelectric performance of functionalized Sc2C MXenes

    KAUST Repository

    Kumar, S.

    2016-07-05

    Functionalization of the MXene Sc2C, which has the rare property to realize semiconducting states for various functionalizations including O, F, and OH, is studied with respect to the electronic and thermal behavior. The lowest lattice thermal conductivity is obtained for OH functionalization and an additional 30% decrease can be achieved by confining the phonon mean free path to 100 nm. Despite a relatively low Seebeck coefficient, Sc2C(OH)2 is a candidate for intermediate-temperature thermoelectric applications due to compensation by a high electrical conductivity and very low lattice thermal conductivity.

  7. QEC value of the superallowed β emitter 42Sc

    Science.gov (United States)

    Eronen, T.; Hardy, J. C.; Canete, L.; Jokinen, A.; Hakala, J.; Kankainen, A.; Kolhinen, V. S.; Koponen, J.; Moore, I. D.; Murray, I. M.; Penttilä, H.; Pohjalainen, I.; Poleshchuk, O.; Reinikainen, J.; Rinta-Antila, S.; Soukouti, N.; Voss, A.; ńystö, J.

    2017-02-01

    The QEC value of the superallowed β+ emitter 42Sc has been measured with the JYFLTRAP Penning-trap mass spectrometer at the University of Jyväskylä to be 6426.350(53) keV. This result is at least a factor of four more precise than all previous measurements, which were also inconsistent with one another. As a byproduct we determine the excitation energy of the 7+ isomeric state in 42Sc to be 616.762(46) keV, which deviates by 8 σ from the previous measurement.

  8. Experimental Progress of DC-SC Photoinjector at Peking University

    CERN Document Server

    Wang, G M; Ding, Y T; Hao, J; Huang, S L; Lin, L; Lu, X Y; Quan, S W; Wang, L F; Xiang, R; Zhang, B C; Zhao, K; Jiao, F; Xie, D; Yang, L; Zhu, F; Liu, C; Wang, F; Xu, W; Liu, Z

    2005-01-01

    Beam loading experiments on DC-SC photoinjector test facility have been finished at 4.4 K. Upon the present experiments, the gradient of 6 MV/m is achieved. The maximum energy gain is 1.1 MeV at 4.4 K. With average beam current of 270 mA, the measured rms emittance is about 5 mm-mrad at the beam energy of 500 keV. Experiments on the test facility has validated that the DC-SC photoinjector is a good choice to provide moderate average current electron beams with low bunch charge and very high repetition rate.

  9. Radiation protection Group (SC/RP) desperately seeking...

    CERN Multimedia

    A. Hervé, Y. Donjoux / SC

    2006-01-01

    We are trying to trace two transit permits (passavants), which constitute the customs clearance documentation for two 'AD6'portable radiation detectors. The two permits (No. 1308 and No. 1309) were sent in the same internal mail envelope towards the middle of March 2006 but never reached their final destination. After weeks of searching in vain, we are now appealing for your help. If you have these two permits in your possession, please get in touch with us. Many thanks in advance. A.HERVE - SC/RP- ( 163168 / 70927) Y.DONJOUX - SC/RP - (160105 / 73171)

  10. Bayesian narrowband interference mitigation in SC-FDMA

    KAUST Repository

    Ali, Anum

    2015-08-12

    This paper presents a novel narrowband interference (NBI) mitigation scheme for SC-FDMA systems. The proposed scheme exploits the frequency domain sparsity of the unknown NBI signal and adopts a low complexity Bayesian sparse recovery procedure. In practice, however, the sparsity of the NBI is destroyed by a grid mismatch between NBI sources and SC-FDMA system. Towards this end, an accurate grid mismatch model is presented and a sparsifying transform is utilized to restore the sparsity of the unknown signal. Numerical results are presented that depict the suitability of the proposed scheme for NBI mitigation.

  11. Scandium functionalized carbon aerogel: Synthesis of nanoparticles and structure of a new ScOCl and properties of NaAlH{sub 4} as a function of pore size

    Energy Technology Data Exchange (ETDEWEB)

    Javadian, Payam; Nielsen, Thomas K. [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark); Ravnsbæk, Dorthe B. [Department of Material Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge 02142, MA (United States); Jepsen, Lars H. [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark); Polanski, Marek [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Plocinski, Tomasz [Faculty of Material Science and Engineering, Warsaw University of Technology, 144 Woloska Str., 02-507 Warsaw (Poland); Kunce, Izabela [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Besenbacher, Flemming [Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Bystrzycki, Jerzy [Faculty of Advanced Technology and Chemistry, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland); Jensen, Torben R., E-mail: trj@chem.au.dk [Center for Energy Materials, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, DK-8000 Aarhus (Denmark)

    2015-11-15

    A new method for scandium-functionalization of carbon aerogels forming nanoparticles of a new scandiumoxochloride, ScOCl is presented. Sodium aluminiumhydride, NaAlH{sub 4}, is successfully melt infiltrated into the nano porous scaffolds with pore sizes of D{sub max}=7, 10, 13, 21, 26 and 39 nm, containing scandium based nano particles (<2.9 wt%) confirmed by elemental analysis and scanning electron microscopy. A systematic study of hydrogen storage properties of the nano composite materials is presented. An aqueous solution of ScCl{sub 3} was initially infiltrated and formed nanoconfined [Sc(OH)(H{sub 2}O){sub 5}]{sub 2}Cl{sub 4}(H{sub 2}O){sub 2}, which transforms to nanoparticles of a new scandium oxochloride, ScOCl at 192 °C and to Sc{sub 2}O{sub 3} at 420 °C. ScOCl crystallizes in an orthorhombic unit cell a=3.4409(8), b=3.9613(6) and c=8.178(2) Å, space group Pmmn, and is built from layers of [ScO{sub 4}Cl{sub 2}] octahedra forming neutral ScOCl layers. Temperature programmed desorption mass spectroscopy shows slightly improved kinetics for release of hydrogen with decreasing pore size. Continuous cycling of hydrogen release and uptake measured by the Sieverts' method reveal a larger preserved hydrogen storage capacity for scandium-functionalized aerogel with the larger pores (39 nm). - Highlights: • New synthesis approach for nanoporous Sc-functionalization carbon aerogel (Sc-CA). • The new scandium oxochloride, ScOCl, structure is obtained. • NaAlH{sub 4} nanoconfined in Sc-CA with pores ranging between 7 nm

  12. Ab-initio studies of the Sc adsorption and the ScN thin film formation on the GaN(000-1)-(2 × 2) surface

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Sánchez, J., E-mail: guerrero@ifuap.buap.mx [Benemérita Universidad Autónoma de Puebla, Instituto de Física “Ing Luis Rivera Terrazas”, Apartado Postal J-48, Puebla 72570 (Mexico); Sánchez-Ochoa, F.; Cocoletzi, Gregorio H.; Rivas-Silva, J.F. [Benemérita Universidad Autónoma de Puebla, Instituto de Física “Ing Luis Rivera Terrazas”, Apartado Postal J-48, Puebla 72570 (Mexico); Takeuchi, Noboru [Universidad Nacional Autónoma de México, Centro de Nanociencia y Nanotecnología, Apartado Postal 2681, Ensenada, Baja California 22800 (Mexico)

    2013-12-02

    First principles total energy calculations have been performed to investigate the initial stages of the Sc adsorption and ScN thin film formation on the GaN(000-1)-(2 × 2) surface. Studies are done within the periodic density functional theory as implemented in the PWscf code of the Quantum ESPRESSO package. The Sc adsorption at high symmetry sites results in the bridge site as the most stable structure. When a Sc monolayer is deposited above the surface the T4 site results as the most stable geometry. The Sc migration into the first Ga monolayer induces the Ga displaced ad-atom to be adsorbed at the T4-2 site. A ScN bilayer may be obtained under the Ga monolayer. Finally a ScN bilayer may be formed in the wurtzite phase above the surface. The formation energy plots show that in the moderate Ga-rich conditions we obtain the formation of a ScN bilayer under the gallium monolayer. However at N-rich conditions the formation of ScN bilayer above the surface is the most favorable structure. We report the density of states to explain the electronic structure of the most favorable geometries. - Highlights: • Studies of the initial stages in the formation of Sc and ScN structures on GaN • In the adsorption of Sc on the GaN the Br site is the most favorable geometry. • When a Sc replaces a Ga of the first monolayer the displaced Ga occupies a T4-2 site. • For Ga-rich conditions there is formation of ScN under the Ga monolayer. • In N-rich conditions there is formation of ScN in the wurtzite phase.

  13. Magnetic and Structural Studies of Sc Containing Ruthenate Double Perovskites A2ScRuO6 (A = Ba, Sr).

    Science.gov (United States)

    Kayser, Paula; Injac, Sean; Ranjbar, Ben; Kennedy, Brendan J; Avdeev, Maxim; Yamaura, Kazunari

    2017-08-07

    Ruthenium-containing double perovskites A2ScRuO6 have been synthesized as polycrystalline powders and structurally characterized using a combination of synchrotron X-ray and neutron powder diffraction methods. When A = Ba, a hexagonal 6L perovskite structure is obtained if the synthesis is conducted at ambient pressure and a rock-salt ordered cubic structure is obtained if the sample is quenched from high pressures. The Sr oxide Sr2ScRuO6 is obtained with a rock-salt ordered corner sharing topology. Heat capacity and bulk magnetic susceptibility measurements show that the three oxides are antiferromagnets. Cubic Ba2ScRuO6 undergoes a metal-insulator transition near 270 K and hexagonal Ba2ScRuO6 is a semiconductor with an activation energy of 0.207 eV. The magnetic structures of the two rock-salt ordered double perovskites were established using powder neutron diffraction and are described by k = (0,0,1) and k = (0,0,0) for the Ba and Sr oxides, respectively, corresponding to type I antiferromagnetic structures, with ferromagnetic layers stacked antiferromagnetically. The ambient-pressure hexagonal polymorph of Ba2ScRuO6 has partial Sc-Ru ordering at both the face-sharing B2O9 dimer and corner-sharing BO6 sites. The magnetic structure is described by k = (1/2,0,0) with the basis vector belonging to the irreducible representation Γ3.

  14. Efficient Photocatalytic Degradation of Norfloxacin in Aqueous Media by Hydrothermally Synthesized Immobilized TiO2/Ti Films with Exposed {001} Facets.

    Science.gov (United States)

    Sayed, Murtaza; Shah, Luqman Ali; Khan, Javed Ali; Shah, Noor S; Nisar, Jan; Khan, Hasan M; Zhang, Pengyi; Khan, Abdur Rahman

    2016-12-22

    In this study, a novel immobilized TiO2/Ti film with exposed {001} facets was prepared via a facile one-pot hydrothermal route for the degradation of norfloxacin from aqueous media. The effects of various hydrothermal conditions (i.e., solution pH, hydrothermal time (HT) and HF concentration) on the growth of {001} faceted TiO2/Ti film were investigated. The maximum photocatalytic performance of {001} faceted TiO2/Ti film was observed when prepared at pH 2.62, HT of 3 h and at HF concentration of 0.02 M. The as-prepared {001} faceted TiO2/Ti films were fully characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM), and X-ray photoelectron spectroscopy (XPS). More importantly, the as-prepared {001} faceted TiO2/Ti film exhibited excellent photocatalytic performance toward degradation of norfloxacin in various water matrices (Milli-Q water, tap water, river water and synthetic wastewater). The individual influence of various anions (SO4(2-), HCO3(-), NO3(-), Cl(-)) and cations (K(+), Ca(2+), Mg(2+), Cu(2+), Na(+), Fe(3+)) usually present in the real water samples on the photocatalytic performance of as-prepared TiO2/Ti film with exposed {001} facet was investigated. The mechanistic studies revealed that (•)OH is mainly involved in the photocatalytic degradation of norfloxacin by {001} faceted TiO2/Ti film. In addition, norfloxacin degradation byproducts were investigated, on the basis of which degradation schemes were proposed.

  15. Surface phenomena of HA/TiN coatings on the nanotubular-structured beta Ti-29Nb-5Zr alloy for biomaterials

    Science.gov (United States)

    Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A.

    2012-01-01

    Surface phenomena of HA/TiN coatings on the nanotubular-structured beta Ti-29Nb-5Zr alloy for biomaterials have been investigated by several experimental methods. The nanotubular structure was formed by anodizing the Ti-29Nb-5Zr alloy in 1 M H3PO4 electrolytes with 1.0 wt.% NaF at room temperature. Hydroxyapatite (HA)/titanium nitride (TiN) films were deposited on Ti-29Nb-5Zr alloy specimens using a magnetron sputtering system. The HA target was made of human tooth-ash by sintering at 1300 °C for 1 h, and the HA target had an average Ca/P ratio of 1.9. The HA/TiN depositions were performed, using the pure HA target, on Ti-29Nb-5Zr alloy following the initial deposition of a TiN buffer layer coating. Microstructures and nanotubular morphology of the coated alloy specimens were examined by FE-SEM, EDX, XRD, and XPS. The Ti-29Nb-5Zr alloy substrate had small grain size and preferred orientation along the drawing direction. The HA/TiN coating was stable with a uniform morphology at the tips of the nanotubes.

  16. The antitumor activity of hydrophobin SC3, a fungal protein

    NARCIS (Netherlands)

    Akanbi, Marijke Haas Jimoh; Post, Eduard; van Putten, Sander M; de Vries, Louwe; Smisterova, Jarmila; Meter-Arkema, Anita H; Wösten, Han A B; Rink, Rick; Scholtmeijer, Karin

    2013-01-01

    The use of mushroom extracts has been common practice in traditional medicine for centuries, including the treatment of cancer. Proteins called hydrophobins are very abundant in mushrooms. Here, it was examined whether they have antitumor activity. Hydrophobin SC3 of Schizophyllum commune was

  17. Electrochemical Characterization of Ni/(Sc)YSZ Electrodes

    DEFF Research Database (Denmark)

    Ramos, Tania; Thydén, Karl Tor Sune; Mogensen, Mogens Bjerg

    2010-01-01

    Investigations of Ni/(Sc)YSZ cermets for solid oxide cells (SOCs) were performed by electrochemical impedance spectroscopy (EIS), under varying experimental conditions and upon redox cycling, using three different designs of symmetric cells. The deconvolution and fitting of the obtained impedance...

  18. Construct Validation of the Sc Scale of the MMPI.

    Science.gov (United States)

    Keane, Susan Phillips; Gibbs, Margaret

    1980-01-01

    Tested the hypothesis that subjects with elevated MMPI profiles would exhibit qualitatively different word associations from those with normal MMPI profiles. Results are interpreted as demonstrating the construct validity of the Sc scale in that the more pathological the profile, the greater degree of cognitive disturbance exhibited. (Author)

  19. Cytogenetic diagnosis of Roberts SC phocomelia syndrome: First ...

    African Journals Online (AJOL)

    Tahir M. Malla

    2015-07-14

    Jul 14, 2015 ... of diagnoses in dysmorphology by approximately 15%. However, metaphase anomalies like PCS/HR and PSCS can- not be detected by techniques like array studies and therefore milder forms of syndromes like those of Roberts SC pho- comelia may remain undetected. We therefore conclude from.

  20. M.Sc. in Civil and Structural Engineering

    DEFF Research Database (Denmark)

    The catalogue contain a list of project ideas proposed by the scientific staff at the Department of Civil Engineering, Aalborg University, and a number of companies. Most of the project ideas in this catalogue may form the basis for long and short candidate projects as well as regular 3rd semester...... projects at the M.Sc. programme in Civil and Structural Engineering....

  1. Calibration of the DLP-SC-3300-02 probe

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Breinbjerg, Olav

    This report douments the calibration measurement of the DLP-SC-3300-02 dual-linearly polarized near-field probe. The measurement comprises radiation pattern, diretivity, gain, spetra of spherial wave coefients, polarization charateristis, and complex channel balance at 41 frequencies, as well...

  2. 44gSc from metal calcium targets for PET

    DEFF Research Database (Denmark)

    Severin, Gregory; Gagnon, K.; Engle, J. W.

    2012-01-01

    A low-cost and efficient method for producing pre-clinical scale quantities of 44gSc is presented. Production involves proton irradiation of natural unenriched calcium metal followed by rapid separation of radioscandium from the target using hydroxmate functionalized resin.© 2012 American Institu...

  3. M.Sc. in Civil and Structural Engineering

    DEFF Research Database (Denmark)

    The following pages contain a list of project ideas proposed by the scientific staff at the Department of Civil Engineering, Aalborg University, and a number of companies. Most of the project ideas in this catalogue may form the basis for long and short master projects as well as regular 3rd...... semester projects at the M.Sc. programme in Civil and Structural Engineering....

  4. M.Sc. in Civil and Structural Engineering

    DEFF Research Database (Denmark)

    Clausen, Johan

    The report contain a list of project ideas proposed by the scientific staff at the Department of Civil Engineering, Aalborg University, and a number of companies. Most of the project ideas in this catalogue may form the basis for long and short candidate projects as well as regular 3rd semester...... projects at the M.Sc. programme in Civil and Structural Engineering....

  5. M.Sc. in Civil and Structural Engineering

    DEFF Research Database (Denmark)

    This catalogue contains a list of project ideas proposed by the scientific staff at the Department of Civil Engineering, Aalborg University, and a number of companies. Most of the project ideas in this catalogue may form the basis for long and short candidate projects as well as regular 3rd...... semester projects at the M.Sc. programme in Civil and Structural Engineering....

  6. Cytogenetic diagnosis of Roberts SC phocomelia syndrome: First ...

    African Journals Online (AJOL)

    Tahir M. Malla

    2015-07-14

    Jul 14, 2015 ... comelia [2]. These two syndromes had varying phenotypic expression and were later concluded as the same entity because of resemblance of thalidomide embryopathy with Robert's syndrome and were therefore termed as Roberts SC pho- comelia syndrome [3]. The gene responsible for the syndrome.

  7. 78 FR 20369 - South Carolina Disaster #SC-00021

    Science.gov (United States)

    2013-04-04

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION South Carolina Disaster SC-00021 AGENCY: U.S. Small Business Administration. ACTION: Notice... dated 03/29/2013. Incident: Windsor Green Condo Complex Fire. Incident Period: 03/16/2013. Effective...

  8. South Carolina's SC LENDS: Optimizing Libraries, Transforming Lending

    Science.gov (United States)

    Hamby, Rogan; McBride, Ray; Lundberg, Maria

    2011-01-01

    Since SC LENDS started operating in June 2009, more public libraries have come on board. All of this on the back end connects to a Mozilla-based staff client that has distributions for Mac OS X and Microsoft Windows, using SSL encryption to keep communications secure and private between remote libraries and the servers hosted at a high-end…

  9. Annual evapotranspiration of a forested wetland watershed, SC

    Science.gov (United States)

    Devendra M. Amatya; Carl Trettin

    2007-01-01

    In this study, hydro-meteorological data collected from 1 964 to 1 9 76 on an approximately 5, 000 ha predominantly forested coastal watershed (Turkey Creek) at the Francis Marion National Forest near Charleston, SC were analyzed to estimate annual evapotranspiration (E T) using four different empirical methods. The first one, reported by Zhang et a/. (2001), that...

  10. Toelating Herbasan SC welkom voor dahlia, A. coronaria en narcis

    NARCIS (Netherlands)

    Leeuwen, van P.J.; Koster, A.T.J.; Trompert, J.P.T.

    2005-01-01

    Onlangs is Herbasan SC voor de onkruidbestrijding in onder meer dahlia, narcis en Anemone coronaria toegelaten. PPO ging na hoe het middel het beste is in te zetten. In dit artikel zijn de resultaten van het onderzoek vermeld en een advies voor toepassing

  11. Experimental investigation on the formation mechanism of the TiFe alloy by the molten-salt electrolytic titanium concentrate

    Directory of Open Access Journals (Sweden)

    Shi R.

    2011-01-01

    Full Text Available The ferrotitanium alloy was prepared in the molten CaCl2 system, in which resolidified ilmenite and the graphite crucible were used as cathode and anode. In this study, the electrolytic voltage was fixed at 3.1V, and three different temperatures were applied: 850oC, 875oC and 900ºC. Finally, the product was examined by SEM and XRD to determine the phase transformation after the electrolysis. The results show that the ilmenite was firstly reduced to Fe, and finally the TiFe alloy was formed. The intermediate products include CaTiO3, TiO2, Ti2O3, TiO, Fe, TiFe2, and Ti. Different product and structure can be obtained by changing temperature. According to thermodynamic calculation, the principal electroreduction products are Ti and TiFe2 and then Ti and TiFe2 are formed by interdiffusion which is governed by temperature.

  12. Update on the NSF PAARE Program at SC State

    Science.gov (United States)

    Walter, Donald K.; Ajello, Marco; Brittain, Sean D.; Cash, Jennifer; Hartmann, Dieter; Ho, Shirley; Howell, Steve B.; King, Jeremy R.; Leising, Mark D.; Smith, Daniel M.

    2017-01-01

    We report on results from our NSF PAARE program during Year 2 of the project. Our partnership under this PAARE award includes South Carolina State University (a Historically Black College/University), Clemson University (a Ph.D. granting institution) as well as individual investigators at NASA Ames and Carnegie Mellon University. Our recent work on variable and peculiar stars, work with the Kepler Observatory and our educational products in cosmology for non-STEM majors will be presented. We have successfully piloted sharing our teaching resources by offering an upper-level astrophysics course taught at Clemson via video conferencing , allowing a graduating senior from SC State to take a course not available through his home institution. Additionally, we are working on a memorandum of agreement between the two institutions that will allow for the seamless transfer of an undergraduate from SC State to Clemson’s graduate program in physics and astronomy. Our curriculum work includes new web-based cosmology activities and laboratory experiments. SC State undergraduates are reporting at this conference on their work with the light curves of semiregular variables using Kepler data. Additionally, we are heavily involved in the Citizen CATE Experiment. A PAARE scholarship student from SC State and the PAARE PI traveled to Indonesia for the March 2016 solar eclipse. Their results are also being presented elsewhere at this conference (see Myles McKay’s poster). Support for this work includes our NSF PAARE award AST-1358913 as well as resources and support provided by Clemson University and the National Optical Astronomy Observatory. Additional support has been provided by the South Carolina Space Grant Consortium and from NASA to SC State under awards NNX11AB82G and NNX13AC24G. CATE work has been supported by NASA SMD award NNX16AB92A to the National Solar Observatory. Additional details can be found at: http://physics.scsu.edu

  13. Excitation functions of alpha particle induced reactions on {sup nat}Ti up to 40 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M.S., E-mail: md.shuzauddin@yahoo.com [Tandem Accelerator Facilities, Institute of Nuclear Science and Technology, Atomic Energy Research Establishment, Savar, Dhaka (Bangladesh); Scholten, B. [Institut für Neurowissenschaften und Medizin, INM-5:Nuklearchemie, Forschungszentrum Jülich, D-52425 Jülich (Germany)

    2016-08-01

    Excitation functions of the reactions {sup nat}Ti(α,x){sup 48}Cr, {sup nat}Ti(α,x){sup 48}V and {sup nat}Ti(α,x){sup 46,48}Sc were determined by the stacked-foil activation technique up to 40 MeV. The radioactivities produced in the {sup nat}Ti target were measured by γ-ray spectrometry using HPGe detector. The reaction {sup nat}Ti(α,x){sup 51}Cr was used to determine the beam parameters. New experimental values for the above reactions have been obtained. An intercomparison of our data with the available literature values has been done. The cross section results obtained in this work could be useful in defining new monitor reactions, radiation safety and isotope production.

  14. Excitation functions of alpha particle induced reactions on natTi up to 40 MeV

    Science.gov (United States)

    Uddin, M. S.; Scholten, B.

    2016-08-01

    Excitation functions of the reactions natTi(α,x)48Cr, natTi(α,x)48V and natTi(α,x)46,48Sc were determined by the stacked-foil activation technique up to 40 MeV. The radioactivities produced in the natTi target were measured by γ-ray spectrometry using HPGe detector. The reaction natTi(α,x)51Cr was used to determine the beam parameters. New experimental values for the above reactions have been obtained. An intercomparison of our data with the available literature values has been done. The cross section results obtained in this work could be useful in defining new monitor reactions, radiation safety and isotope production.

  15. Apical P2XR contribute to [Ca2+]i signaling and Isc in mouse renal MCD.

    Science.gov (United States)

    Li, Liuzhe; Lynch, I Jeanette; Zheng, Wencui; Cash, Melanie N; Teng, Xueling; Wingo, Charles S; Verlander, Jill W; Xia, Shen-Ling

    2007-08-03

    We examined P2X receptor expression and distribution in the mouse collecting duct (CD) and their functional role in Ca(2+) signaling. Both P2X(1) and P2X(4) were detected by RT-PCR and Western blot. Immunohistochemistry demonstrated apical P2X(1) and P2X(4) immunoreactivity in principal cells in the outer medullary CD (OMCD) and inner medullary CD (IMCD). Luminal ATP induced an increase in Ca(2+) signaling in native medullary CD (MCD) as measured by fluorescence imaging. ATP also induced an increase in Ca(2+) signaling in MCD cells grown in primary culture but not in the presence of P2XR antagonist PPNDS. Short circuit current (I(sc)) measurement with mouse IMCD cells showed that P2XR agonist BzATP induced a larger I(sc) than did P2YR agonist UTP in the apical membrane. Our data reveal for the first time that P2X(1) and P2X(4) are cell-specific with prominent immunoreactivity in the apical area of MCD cells. The finding that P2XR blockade inhibits ATP-induced Ca(2+) signaling suggests that activation of P2XR is a key step in Ca(2+)-dependent purinergic signaling. The result that activation of P2XR produces large I(sc) indicates the necessity of P2XR in renal CD ion transport.

  16. Desulfurizing Ability of the CaOsatd.-CaCl2-CaF2 Slags

    Science.gov (United States)

    Liu, Jiazhan; Kobayashi, Yoshinao

    2017-04-01

    Desulfurizing ability of the CaO-CaCl2-CaF2 slags saturated with CaO has been investigated from the viewpoint of the sulfide capacity and CaO solubility. The CaO-CaCl2-CaF2 slags containing small amounts of Cu2O and CaS were inserted in a CaO crucible with metallic copper. The CaO crucible was sealed in a nickel holder to prevent the evaporation of CaCl2, then heated up and kept at temperatures from 1573 K (1300 °C) to 1673 K (1400 °C) for 24 hours, which enabled the system inside the CaO crucible to reach the equilibrium. As expected, the sulfide capacity derived from the data obtained as well as CaO solubility of the slag increase with an increase in temperature at a constant ratio of CaCl2/CaF2. The solubility of CaO increases by the replacement of CaF2 with CaCl2, whereas the sulfide capacity slightly decreases and the activity coefficient of CaS ( γ CaS) increases. This suggests that CaF2 has stronger interaction with CaS than CaCl2. The sulfur distribution ratio between carbon-saturated iron melts and the CaO-CaCl2 slag has been calculated to be about 10 000 at 1573 K (1300 °C) using the sulfide capacity obtained, which value is still large enough even with the replacement of CaF2 by CaCl2.

  17. Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency.

    Science.gov (United States)

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A

    2012-07-27

    Tremendous interest exists towards synthesizing nanoassemblies for dye-sensitized solar cells (DSSCs) using earth-abundant and -friendly materials with green synthetic approaches. In this work, high surface area TiO(2) nanowire arrays were grown on the surface of functionalized graphene sheets (FGSs) containing -COOH functionalities acting as a template by using a sol-gel method in the green solvent, supercritical carbon dioxide (scCO(2)). The effect of scCO(2) pressure (1500, 3000 and 5000 psi), temperature (40, 60 and 80 °C), acetic acid/titanium isopropoxide monomer ratios (HAc/TIP = 2, 4 and 6), functionalized graphene sheets (FGSs)/TIP weight ratios (1:20, 1:40 and 1:60 w/w) and solvents (EtOH, hexane) were investigated. Increasing the HAc/TIPweight ratio from 4 to 6 in scCO(2) resulted in increasing the TiO(2) nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO(2) with the -COOH groups on the surface of the graphene sheets, indicating that graphene acted as a template for polycondensation growth. UV-vis diffuse reflectance and photoluminescence spectroscopy showed a reduction in titania's bandgap and also a significant reduction in electron-hole recombination compared to bare TiO(2) nanowires. Photocurrent measurements showed that the TiO(2)nanowire/graphene composites prepared in scCO(2) gave a 5× enhancement in photoefficiency compared to bare TiO(2) nanowires.

  18. Teale CA. Counties

    Data.gov (United States)

    California Department of Resources — California Spatial Information System (CaSIL) is a project designed to improve access to geo-spatial and geo-spatial related data information throughout the state of...

  19. Low elastic modulus Ti-Ta alloys for load-bearing permanent implants: enhancing the biodegradation resistance by electrochemical surface engineering.

    Science.gov (United States)

    Kesteven, Jazmin; Kannan, M Bobby; Walter, Rhys; Khakbaz, Hadis; Choe, Han-Choel

    2015-01-01

    In this study, the in vitro degradation behaviour of titanium-tantalum (Ti-Ta) alloys (10-30 wt.% Ta) was investigated and compared with conventional implant materials, i.e., commercially pure titanium (Cp-Ti) and titanium-aluminium-vanadium (Ti6Al4V) alloy. Among the three Ti-Ta alloys studied, the Ti20Ta (6.3×10(-4) mm/y) exhibited the lowest degradation rate, followed by Ti30Ta (1.2×10(-3) mm/y) and Ti10Ta (1.4×10(-3) mm/y). All the Ti-Ta alloys exhibited lower degradation rate than that of Cp-Ti (1.8×10(-3) mm/y), which suggests that Ta addition to Ti is beneficial. As compared to Ti6Al4V alloy (8.1×10(-4) mm/y), the degradation rate of Ti20Ta alloy was lower by ~22%. However, the Ti30Ta alloy, which has closer elastic modulus to that of natural bone, showed ~48% higher degradation rate than that of Ti6Al4V alloy. Hence, to improve the degradation performance of Ti30Ta alloy, an intermediate thin porous layer was formed electrochemically on the alloy followed by calcium phosphate (CaP) electrodeposition. The coated Ti30Ta alloy (3.8×10(-3) mm/y) showed ~53% lower degradation rate than that of Ti6Al4V alloy. Thus, the study suggests that CaP coated Ti30Ta alloy can be a viable material for load-bearing permanent implants. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Fabrication and characterization of Ti-Nb-HA alloy by mechanical alloying and spark plasma sintering for hard tissue replacements

    Science.gov (United States)

    Singh, Ramandeep; Pal Singh, Bhupinder; Gupta, Anjali; Prakash, Chander

    2017-08-01

    In the present research work, a β-type Ti-35Nb-10HA alloy was successfully fabricated by mechanical alloying of titanium (Ti), niobium (Nb), and hydroxyaptite (HA) powders followed by consolidation using Spark Plasma Sintering technique. The effect of HA on the microstructure and mechanical properties were studied. The microstructure, surface topography, and element composition of the Ti-Nb-HA alloy was investigated using optical microscope, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The micro-hardness of the specimens was measured on a Vickers hardness tester. The microstructure examination of the compact revealed that the alloy distinctly shows the primary grain boundaries along with secondary grain boundary. It was observed that complex reactions between HA and alloy elements occurred during the sintering process of Ti-35Nb-10HA alloy and biocompatible phases [Ca3(PO4)2, CaTiO3, Nb8P5, CaO, TiP, Nb4O5, and TiO2] were generated in the compact, which is beneficial to form apatite and improved the bioactivity of the alloy for osseiointegartion. The fabricated Ti-35Nb-15HA alloy exhibits maximum micro-hardness (∼786 HV), which is very high value as compared to the alloys reported in literature. Based on these above observations, it is expected that the as-fabricated Ti-35Nb-10HA alloy is suggested for dental and orthopaedic applications.

  1. Nanomechanical properties of TiCN and TiCN/Ti coatings on Ti prepared by Filtered Arc Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yong [School of Mechanical, Materials & Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Lu, Cheng, E-mail: chenglu@uow.edu.au [School of Mechanical, Materials & Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Yu, Hailiang [School of Mechanical, Materials & Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); School of Mechanical Engineering, Shenyang University, Shenyang 110044 (China); Kiet Tieu, A.; Su, Lihong; Zhao, Yue; Zhu, Hongtao [School of Mechanical, Materials & Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Kong, Charlie [Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052 (Australia)

    2015-02-11

    Monolayer TiCN and multilayer TiCN/Ti coatings were deposited on the surface of Ti using the Filtered Arc Deposition System (FADS). Nanoindentation tests were performed on both coatings. The multilayer TiCN/Ti coating exhibited better ductility than the monolayer TiCN coating. The lattice constants of the coatings were characterized by X-ray diffraction. Transmission Electron Microscopy (TEM) was used to investigate the fracture behavior of the coatings. Inter-columnar, inclined and lateral cracks were found to be the dominant crack modes in the monolayer TiCN coatings while small bending crack and radial crack were the dominant crack modes in the multilayer TiCN/Ti coatings. The Finite Element Method (FEM) was used to simulate the indentation process. It was found that the Ti interlayer in the multilayer TiCN/Ti coating could efficiently suppress the fracture, which is responsible for the improved ductility of the multilayer TiCN/Ti coating.

  2. On new ternary equiatomic scandium transition metal aluminum compounds ScTAl with T = Cr, Ru, Ag, Re, Pt, and Au

    Energy Technology Data Exchange (ETDEWEB)

    Radzieowski, Mathis; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Haverkamp, Sandra [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; University of Sao Paulo, Sao Carlos, SP (Brazil). Inst. of Physics

    2016-08-01

    The new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn{sub 2} type, P6{sub 3}/mmc, a = 525.77(3), c = 858.68(5) pm, R{sub 1} = 0.0188, wR{sub 2} = 0.0485, 204 F{sup 2} values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R{sub 1} = 0.0326, wR{sub 2} = 0.0458, 448 F{sup 2} values, 20 variables and ScAuAl, HfRhSn type, P anti 62c, a = 722.88(4), c = 724.15(4) pm, R{sub 1} = 0.0316, wR{sub 2} = 0.0653, 512 F{sup 2} values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by {sup 27}Al and {sup 45}Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

  3. Computational approaches for interpreting scRNA-seq data.

    Science.gov (United States)

    Rostom, Raghd; Svensson, Valentine; Teichmann, Sarah A; Kar, Gozde

    2017-08-01

    The recent developments in high-throughput single-cell RNA sequencing technology (scRNA-seq) have enabled the generation of vast amounts of transcriptomic data at cellular resolution. With these advances come new modes of data analysis, building on high-dimensional data mining techniques. Here, we consider biological questions for which scRNA-seq data is used, both at a cell and gene level, and describe tools available for these types of analyses. This is an exciting and rapidly evolving field, where clustering, pseudotime inference, branching inference and gene-level analyses are particularly informative areas of computational analysis. © 2017 The Authors. FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.

  4. Comparative analysis of equalization methods for SC-FDMA

    DEFF Research Database (Denmark)

    Dogadaev, Anton Konstantinovich; Kozlov, Alexander; Ukhanova, Ann

    2010-01-01

    In this paper we introduce comparative analysis for different types of equalization schemes, based on the minimum mean square error (MMSE) optimization. The following types of equalizers were compared: linear equalization, decision feedback equalization (DFE) and turbo equalization. Performance...... and complexity of these schemes were tested for Single Carrier Frequency Division Multiple Access (SC-FDMA) system with Single Input Single Output (SISO) antenna configuration. SC-FDMA is a common technique, which is used in the UTRA LTE Uplink, so the results of complexity and performance analysis could...... be applied to find the appropriate equalization algorithm to be used in the Uplink channel of the LTE – the famous standard in 4G telecommunications. Simulation results in the end in this paper show bit error ratio (BER) and modulation error ratio (MER) for compared schemes....

  5. Collective high spin states in {sup 45}Sc

    Energy Technology Data Exchange (ETDEWEB)

    Bednarczyk, P. [Institute of Nuclear Physics, Krakow (Poland)]|[INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Styczen, J. [Institute of Nuclear Physics, Krakow (Poland); Broda, R. [Institute of Nuclear Physics, Krakow (Poland); Lach, M. [Institute of Nuclear Physics, Krakow (Poland); Meczynski, W. [Institute of Nuclear Physics, Krakow (Poland); Bazzacco, D. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Brandolini, F. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); De Angelis, G. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Lunardi, S. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Mueller, L. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Medina, N. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Petrache, C. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Rossi-Alvarez, C. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Scarlassara, F. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Segato, G.F. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Signorini, C. [Dipartimento di Fisica dell`Universita and INFN, Padova (Italy); Soramel, F. [Dipartimento di Fisica dell`Universita and INFN, Udine (Italy)

    1995-02-06

    The high-spin states in {sup 45}Sc were studied with the GASP multidetector array. The nuclei were excited by the {sup 30}Si({sup 18}O,p2n){sup 45}Sc reaction at E{sub LAB}=60 MeV and separated with the Recoil Mass Spectrometer. Several new high-spin levels extending the known single-particle and collective structures were observed. Energies of the negative-parity states agree with the shell model predictions whereas the positive-parity-intruder rotational band extends up to very high rotational frequencies and continues beyond the maximum angular momentum available from the single-particle f{sub 7/2} configuration. ((orig.)).

  6. Conductivity of SrTiO3 based oxides in the reducing atmosphere at high temperature

    DEFF Research Database (Denmark)

    Hashimoto, Shin-Ichi; Poulsen, Finn Willy; Mogensen, Mogens Bjerg

    2007-01-01

    The conductivities of several donor-doped SrTiO3 based oxides, which were prepared in air, were studied in a reducing atmosphere at high temperature. The conductivities of all specimens increased slowly with time at 1000 degrees C in 9% H-2/N-2, even after 100 h. Nb-doped SrTiO3 showed relatively...... at 500-800 degrees C, while that of La-doped SrTiO3 dropped immediately on exposure to air. The conduction behavior of Nb-doped SrTiO3 was explained by reduction of Ti4+ and/or Nb5+ and the relatively slow oxygen diffusibility. (c) 2006 Elsevier B.V. All rights reserved.......The conductivities of several donor-doped SrTiO3 based oxides, which were prepared in air, were studied in a reducing atmosphere at high temperature. The conductivities of all specimens increased slowly with time at 1000 degrees C in 9% H-2/N-2, even after 100 h. Nb-doped SrTiO3 showed relatively...... fast reduction and high conductivity compared with the other SrTiO3 based oxides. The conductivity of Nb-doped SrTiO3 was ca. 50 S cm(-1) at 500 degrees C after reduction at 1200 degrees C. After strong reduction, the conductivity of Nb-doped SrTiO3 was almost independent of the oxygen partial pressure...

  7. Electrolytic reduction of mixed (Fe, Ti) oxide using molten calcium chloride electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Panigrahi, Mrutyunjay, E-mail: mp@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan); Iizuka, Atsushi; Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Tan et al. have electrolyzed mixtures of TiO{sub 2} and Fe{sub 2}O{sub 3} to produce alloys containing Fe-Ti intermetallic phases such as FeTi and Fe{sub 2}Ti using the FFC process. However, the produced alloys have a porous structure with many carbon impurities, e.g., titanium carbide (TiC). Most of the carbon contamination could be caused by the presence of carbon particles in the porous alloy structure. They did not mention any obvious ways of excluding carbon and other impurities, and only suggested that the use of mixed oxides with refined structures or using a single phase, namely ilmenite (FeO{center_dot}TiO{sub 2}), were methods of decreasing impurities in the formed alloys. For future industrialization, there is an urgent need for obvious ways of producing purer Fe-Ti alloys with dense structures, rather than porous structures, as these absorb carbon impurities. Black-Right-Pointing-Pointer Finally, we successfully reduced to a highly purified Fe-Ti intermetallic alloy of FeTi and {beta}-Ti (FeTi{sub 4}) phases. FeTi phases of size around 5-10 {mu}m were dispersed in a matrix of the {beta}-Ti (FeTi{sub 4}) phase. The carbon content of the electrolyzed alloy was as low as less than 0.01 mass%. It was suggested that the dense structure of the alloy of FeTi and {beta}-Ti (FeTi{sub 4}) avoided the inclusion of carbon particle impurities, unlike the porous alloy structure. - Abstract: The production of high-purity metals or alloys using effective technologies is critical for future industrialization. With this aim in mind, a fundamental study of electrolysis in molten CaCl{sub 2} electrolytes was conducted to develop a new production process for ferrotitanium (Fe-Ti) intermetallic alloys. Mixed solid oxides of TiO{sub 2} and Fe{sub 2}O{sub 3} were used in a molar ratio of 5.44:1.00. In this composition of Ti and Fe, FeTi and {beta}-Ti containing iron can co-exist in equilibrium. A mixed solid (Fe, Ti) oxide was reduced

  8. The PHENIX PbSc calorimeter and its performance

    Energy Technology Data Exchange (ETDEWEB)

    David, G.; Goto, Y.; Kistenev, E. [and others

    1997-11-01

    The authors have recently completed the production of the 15552 channel PbSc Electromagnetic calorimeter for the PHENIX experiment at RHIC. The design features a single 4 tower module which is repeated throughout and which was produced with a number of QC steps designed to achieve consistent, large light yield in all channels. They present results on uniformity of the calorimeter, accuracy of a cosmic muon based precalibration scheme and test beam performance.

  9. Luminescence Properties of ScPO{sub 4} Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A.; Trukhin, A.N.

    1999-08-16

    Flux-grown ScPO{sub 4} single crystals exhibit a number of luminescence bands in their x-ray-excited luminescence spectra - including sharp lines arising from rare-earth elements plus a number of broad bands at 5.6 cV, 4.4 eV, and 3 eV. The band at 5.6 eV was attributed to a self-trapped exciton (STE) [l], and it could be excited at 7 eV and higher energies. This luminescence is strongly polarized (P = 70 %) along the optical axes of the crystal and exhibits a kinetic decay time constant that varies from several ns at room temperature to {approximately}10 {micro}s at 60 K and up to {approximately}1 ms at 10 K. It is assumed that the STE is localized on the SC ions. The band at 3 eV can be excited in the range of the ScPO{sub 4} crystal transparency (decay time = 3 to 4 {micro}s.) This band is attributed to a lead impurity that creates different luminescence centers. At high temperatures, the band at 4.4 eV is dominant in the x-ray-excited TSL and afterglow spectra. Its intensity increases with irradiation time beginning at zero at the initial irradiation time. The 4.4 eV band does not appear in a fast process under a pulsed electron beam, showing that accumulation is necessary for its observation. A sample of ScPO{sub 4} doped with vanadium exhibited a prevalent band at 4.4 eV at T = 480 K.

  10. QUALITY MANAGEMENT OF BAKERY PRODUCTS: A CASE STUDY IN SC

    Directory of Open Access Journals (Sweden)

    Nicoleta- Luminiţa STRÂMBEANU RISTEA

    2013-01-01

    Full Text Available The paper aimed to present the benefits of implementing HACCP (Hazard Analysis and Critical Control Points to company S.C. "DOBRE AND SONS" S.R.L. Constanta, Romania. The data have been provided by the above mentioned manufacturer. The objectives of S.C. "DOBRE AND SONS" S.R.L. are protecting the health of the consumers of the products and their satisfaction regarding the consumption of products that are nutritional, tasty, fresh, free from microbiological, chemical and physical hazard, as well as possessing stable properties during the validity for consumption. In this respect, there has been implemented and maintained an integrated management system of food quality and safety according to SR EN ISO 9001:2008, SR EN ISO 22000:2005 and according to IFS standard, version 5/2007, which consists of determining the potential biological, chemical and physical hazards that might affect the safety of bread and bakery products, or the health of the consumer. HACCP team is analyzing hazard using one of the recommended techniques: brainstorming or the cause - effect diagram. In conclusion, the company S.C. "DOBRE AND SONS" S.R.L. Constanta, Romania provides awareness and employee involvement at all levels in achieving the appointed objectives.

  11. Development of β Type Ti23Mo-45S5 Bioglass Nanocomposites for Dental Applications

    Directory of Open Access Journals (Sweden)

    Karolina Jurczyk

    2015-11-01

    Full Text Available Titanium β-type alloys attract attention as biomaterials for dental applications. The aim of this work was the synthesis of nanostructured β type Ti23Mo-x wt % 45S5 Bioglass (x = 0, 3 and 10 composites by mechanical alloying and powder metallurgy methods and their characterization. The crystallization of the amorphous material upon annealing led to the formation of a nanostructured β type Ti23Mo alloy with a grain size of approximately 40 nm. With the increase of the 45S5 Bioglass contents in Ti23Mo, nanocomposite increase of the α-phase is noticeable. The electrochemical treatment in phosphoric acid electrolyte resulted in a porous surface, followed by bioactive ceramic Ca-P deposition. Corrosion resistance potentiodynamic testing in Ringer solution at 37 °C showed a positive effect of porosity and Ca-P deposition on nanostructured Ti23Mo 3 wt % 45S5 Bioglass nanocomposite. The contact angles of glycerol on the nanostructured Ti23Mo alloy were determined and show visible decrease for bulk Ti23Mo 3 wt % 45S5 Bioglass and etched Ti23Mo 3 wt % 45S5 Bioglass nanocomposites. In vitro tests culture of normal human osteoblast cells showed very good cell proliferation, colonization, and multilayering. The present study demonstrated that porous Ti23Mo 3 wt % 45S5 Bioglass nanocomposite is a promising biomaterial for bone tissue engineering.

  12. Reduction of the thermal conductivity of the thermoelectric material ScN by Nb alloying

    DEFF Research Database (Denmark)

    Tureson, Nina; Van Nong, Ngo; Fournier, Daniele

    2017-01-01

    samples exhibit a high carrier density of the order of 1021 cm−3. Inclusion of heavy transition metals into ScN enables the reduction in thermal conductivity by an increase in phonon scattering. The Nb inserted ScN thin films exhibited a thermal conductivity lower than the value of the ScN reference (10...

  13. Effect of nano-CeO2 on microstructure properties of TiC/TiN+ TiCN ...

    Indian Academy of Sciences (India)

    In this study, Al3Ti+TiC/TiN+nano-CeO2 laser-cladded coatings have been studied by means of X-ray diffraction and scanning electron microscope. X-ray diffraction results indicated that Al3Ti+TiC/TiN+nano-CeO2 laser-cladded coating consisted of Ti3Al, TiC, TiN, Ti2Al20Ce, TiC0.3N0.7, Ce(CN)3 and CeO2, this phase ...

  14. ScRu2B3 and Sc2RuB6: Borides Featuring a 2D Infinite Boron Clustering.

    Science.gov (United States)

    Salamakha, Leonid P; Sologub, Oksana; Stöger, Berthold; Rogl, Peter Franz; Waas, Monika; Kapustianyk, Volodymyr B; Bauer, Ernst

    2017-09-05

    Two borides, ScRu2B3 and Sc2RuB6, were obtained by argon-arc melting of the elements followed by annealing at 800 °C. ScRu2B3 exhibits a new structure type with the space group Cmcm (a = 3.0195(2) Å, b = 15.4056(8) Å, c = 5.4492(3) Å; single crystal X-ray data; RF(2) = 0.0105). Sc2RuB6 adopts the Y2ReB6-type structure (space group Pbam; a = 8.8545(2) Å, b = 11.1620(3) Å, c = 3.4760(1) Å; single crystal X-ray data; RF(2) = 0.0185). ScRu2B3 displays an unusual intergrowth of CeCo3B2- and AlB2-related slabs; a striking feature is a boat configuration of puckered boron hexagons within infinite graphite like boron layers (6(3) nets). Sc2RuB6 presents two-dimensional planar nets of condensed boron pentagons, hexagons, and heptagons sandwiched between metal layers. In Sc/Y substituted Y2ReB6-type, Y atoms are distributed exclusively inside the boron heptagons. Exploration of the Sc-Ru-B system at 800 °C including binary boundaries employing EPMA and powder X-ray diffraction technique furthermore rules out the existence of previously reported "ScRuB4" but confirms the formation and crystal structure of Sc2Ru5B4. ScRu4B4 forms in cast alloys (LuRu4B4-type structure; space group I41/acd (No. 142), a = 7.3543(2) Å, c = 14.92137(8) Å). Cell parameters and atomic coordinates have been refined for ScRu2B3, Sc2RuB6, and ScRu4B4 in the scope of the generalized gradient approximation. Ab initio electronic structure calculations indicate a moderate electronic density of states at the Fermi level situated near the upper edge of essentially filled d-bands. Electrical resistivity measurements characterize ScRu2B3 and Sc2RuB6 as metals in concord with electronic band structure calculations.

  15. "Dancing inside the ball": the structures and nonlinear optical properties of three Sc2S@C3v(8)-C82 isomers.

    Science.gov (United States)

    Gao, Feng-Wei; Gao, Ying; Wang, Li-Jie; Xu, Hong-Liang; Sun, Shi-Ling; Su, Zhong-Min

    2015-10-01

    Recently, the crystal structures and electrochemical properties of the isomers (Sc2S "trapped" in C82) have been reported, in which the Sc2S is located inside the different positions of the C82 cage. In the present work, three isomers of endohedral metallofullerenes Sc2S@C3v(8)-C82 (A, B, and C) have been designed to explore the effect of the position of Sc2S on their interaction energies and nonlinear optical properties. Among three isomers, the Sc2S is located in different positions of the C82 cage: the angles of Sc-S-Sc in A, B, and C are 104.9, 114.8, and 115.7°, respectively. Furthermore, the analysis of natural bond orbital (NBO) charge indicates that the electron-transfer is from the Sc2S to the adjacent carbon atoms of the C82 cage. The interaction energy of B is the smallest among three isomers which is -226.2 kcal mol(-1). It was worth mentioning that their first hyperpolarizabilities (β tot) were studied, we found that their β tot values were related to the positions of Sc2S: C (2100) > B (1191) > A (947 au). We hope that the present work can provide a new strategy to promote the nonlinear optical properties of endohedral metallofullerenes by changing the positions of the encapsulated molecular. Graphical abstract Three isomers of endohedral metallofullerenes Sc2S@C3v(8)-C82 (A, B, and C) have been designed to explore the position effect of Sc2S on the interaction energies and nonlinear optical properties. Among three isomers, the Sc2S in B has the most stable position. Significantly, the first hyperpolarizability is related to the position of Sc2S inside the C82 cage, which provides a novel strategy to enhance the first hyperpolarizability by the Sc2S revolving inside the C82 cage.

  16. Performance comparison of dye-sensitized solar cells by using different metal oxide- coated TiO2 as the photoanode

    Directory of Open Access Journals (Sweden)

    Sun Xuhui

    2014-01-01

    Full Text Available In order to increase the conversion efficiency of dye-sensitized solar cells, TiO2 photoanode surface is often covered with a metal oxide layer to form a core-shell composite structure. Different metal oxide coating on TiO2 as composite photoanodes can affect the cell efficiency variously. However, there still lacks the crosswise comparison among the effects of different metal oxides on TiO2 photoanode. In this study, TiO2 was coated with Al2O3, CaO, ZnO, MgO, Fe2O3 or Bi2O3 separately by liquid phase deposition method. The results indicated that cells with TiO2/Al2O3, TiO2/ZnO, TiO2/CaO, or TiO2/MgO composite film as a photoanode had higher conversion efficiency than those with un-coated TiO2 films. TiO2/Al2O3 showed the highest efficiency and TiO2/CaO ranked second. On the contrary, cells with TiO2/Bi2O3 or TiO2/Fe2O3 composite film as a photoanode had lower conversion efficiency than those with un-coated TiO2 films. The mechanism of the cell efficiency change was also investigated. To get higher conversion efficiency, matched energy level of the metal oxide with TiO2 is the first prerequisite, and then the optimum coating thickness is also a necessary condition.

  17. Biomarker CA125

    DEFF Research Database (Denmark)

    Kargo, Anette Stolberg

    Background: The majority of patients with ovarian cancer (OC) are diagnosed with advanced disease (70-80 %) and will experience disease relapse with only limited curative potential. Early initiation of relapse treatment based on rising CA125 alone does not improve survival. Increasing CA125 can...... be detected months before symptoms arise and recurrence is visible on imaging. Therefore, biochemical detection of potential relapse by CA125 assessment can cause significant distress. A decision aid (DA) is a tool that provides information and describes advantages and disadvantages of a specific intervention...... patient organisations and cancer societies. First, a focus group of seven former OC patients was performed followed by a quantitative rating of the DA pilot version. The DA was adapted accordingly and then tested in 14 OC patients with recurrence using a structured interview guide (alpha testing). A final...

  18. Spin distribution in preequilibrium reactions for 48Ti + n.

    Energy Technology Data Exchange (ETDEWEB)

    Dashdorj, Dugersuren [North Carolina State Univ., Raleigh, NC (United States)

    2005-04-12

    Cross section measurements were made of prompt γ-ray production as a function of incident neutron energy on a 48Ti sample. Partial γ-ray cross sections for transitions in 45-48Ti, 44-48Sc, and 42-45Ca have been determined. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction γ rays were detected with the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The γ-ray excitation functions were converted to partial γ-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). The data are presented for neutron energies En between 1 to 200 MeV. These results are compared with model calculations which include compound nuclear and pre-equilibrium emission. The model calculations are performed using the STAPRE reaction code for En up to 20 MeV and the GNASH reaction code for En up to 120 MeV. Using the GNASH reaction code the effect of the spin distribution in preequilibrium reactions has been investigated. The preequilibrium reaction spin distribution was calculated using the quantum mechanical theory of Feshbach, Kerman, and Koonin (FKK). The multistep direct (MSD) part of the FKK theory was calculated for a one-step process. The contribution from higher steps is estimated to be small. The spin distribution of the multistep compound (MSC) part of FKK theory is assumed to be the same as in the compound nucleus. The FKK preequilibrium spin distribution was incorporated into the GNASH calculations and the γ-ray production cross sections were calculated and compared with experimental data. The difference in the partial γ-ray cross sections using spin distributions with and without

  19. Fabrication and characterization of laminated Ti-(TiB+La2O3/Ti composite

    Directory of Open Access Journals (Sweden)

    Yuanfei Han

    2015-10-01

    Full Text Available The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness, while inevitably reduce the plasticity and ductility. In this study, in situ synthesized multilayer Ti-(TiB+La2O3/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties. The Ti-(TiB+La2O3/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling. The method has the synthesize advantages with in-situ reaction of Ti and LaB6 at high temperature and controllability of reinforcements size and constituent phases in composites. The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050 °C. The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction. The thickness of pure Ti layer and (TiB+La2O3/Ti composite layer decreased from 1 mm to about 200 μm. Meanwhile, the grains size was refined obviously after rolling deformation. The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB+La2O3/Ti composite improved from 13% to 17% in comparison with the uniform (TiB+La2O3/Ti composite, while the tensile strength had little change. It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB+La2O3/Ti composites.

  20. Osteoblast differentiation and phenotype expressions on chitosan-coated Ti-6Al-4V.

    Science.gov (United States)

    Lin, Hsin-Yi; Chen, Jing-Huei

    2013-09-12

    Chitosan (C), alginate-crosslinked chitosan (CA), and pectin-crosslinked chitosan (CP) were covalently bonded to Ti-6Al-4V surfaces and tested for their biocompatibility. Compared to the clinically treated Ti-6Al-4V surface (Ti64), C, CA, and CP, had higher contact angles and promoted higher cell proliferation, type I collagen deposition, and mineralization after two weeks (all pcrosslinking with alginate and pectin changed surface wettability as well as the swelling and drug release properties of the chitosan coatings. Cells on the coatings had higher proliferation, type I collagen deposition, and degree of mineralization compared to those on Ti64. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. A study on the mechanism of protein adsorption to TiO2.

    Science.gov (United States)

    Ellingsen, J E

    1991-08-01

    The hypothesis that calcium ions adsorb to TiO2 and further to macromolecules with high affinity for Ca2+ was tested. The reaction of human serum proteins with TiO2 was examined and compared with the reaction with hydroxyapatite. The oxide covered titanium surfaces reacted with calcium when exposed to CaCl2 and calcium was identified to a depth of 17 nm into the oxide layer. Surface adsorbed serum proteins were dissolved by EDTA and analysis by the SDS-PAGE technique revealed that the surfaces of TiO2 and hydroxyapatite appeared to take up the same proteins selectively from human serum. Albumin, prealbumin and IgG were identified by immunoelectrophoresis. It is suggested that calcium binding may be one mechanism by which proteins adsorb to TiO2. It is well established that this is the case with hydroxyapatite.

  2. Synthesis of AlN-TiN nanostructured composite powder by reactive ball milling and subsequent thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Mashhadi, H. Amini, E-mail: hossein1@shock.smrc.kumamoto-u.ac.j [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Manikandan, P.; Suetsugu, R. [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Tanaka, S. [Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan); Hokamoto, K. [Shock Wave and Condensed Matter Research Center, Kumamoto University, 2-39-1 Kurokami, Kumamoto (Japan)

    2010-09-17

    Research highlights: {yields} A part of AlN was found to be gradually reduced by Ti during MA and Ti(Al,N) solid solution formed after early stages of milling. {yields} The particle size of supersaturated Ti(Al,N) solid solution and AlN reduced to submicron size and nanocrystalline structure as evident from XRD and SEM results. {yields} The lattice parameter and interplanar distance of Ti shows that all of the decomposed Al dissolved in the Ti lattice by MA and causes its contraction, while only 1 at.% of N dissolves to form Ti(Al,N) solid solution and leads to its dilation and the remaining N reacts with Ti to form TiN. {yields} Annealing of 360 ks MA powder leads to phase transformation as a result of increased thermal diffusivity, the formation of more TiN phase with more under-stoichiometric characteristic, as well as stress releasing and grain growth. - Abstract: In the present article, synthesis of AlN-TiN nanostructured composite by high-energy ball milling process (HEM) of Ti and AlN by 1:1 molar ratio and subsequent heat treatment was investigated. The microstructural evolution of samples was studied by scan electron microscopy (SEM) and energy dispersive X-ray analysis (EDS), composition map analysis by electron probe micro-analyzer (EPMA) and phase determination using X-ray diffraction (XRD) patterns. It was found that a Ti(Al,N) solid solution was formed at the early stages of milling and while Al causes the Ti lattice to contract, N has the opposite effect. The nonlinear variation of interplanar distance and c/a ratio of Ti is considered due to the competition between these two processes during MA and finally led to complete dissolution of Al and only 1 at.% of N in Ti lattice. On further milling, mechanochemical reaction between Ti solid solution and AlN took place in the gradual mode which led to the formation of TiN with an average crystallite size of 10 nm. It is generally acknowledged that the reactions between Ti and AlN includes three stages: (i

  3. Growth of 1-D TiO2 Nanowires on Ti and Ti Alloys by Oxidation

    OpenAIRE

    Huyong Lee; Suliman Dregia; Sheikh Akbar; Mansour Alhoshan

    2010-01-01

    The growth of titania nanowires by a simple metal oxidation process was investigated for both commercially pure α-Ti and Ti alloys including Ti64 and β-Ti under a limited supply of oxygen. The effects of processing variables including heat treatment temperature, gas flow rate, and process duration on the growth of nanowires were explored. Similarities and differences in the growth of nanowires on pure Ti versus Ti alloys were observed. While the growth window in terms of temperature and flow ...

  4. Removal of bovine serum albumin from wastewater using fouling resistant ultrafiltration membranes based on the blends of cellulose acetate, and PVP-TiO2 nanoparticles.

    Science.gov (United States)

    Gebru, Kibrom Alebel; Das, Chandan

    2017-09-15

    Fouling resistant ultrafiltration membranes based on the blends of polyvinylpyrrolidone (PVP), TiO2 nanoparticles and cellulose acetate, CA-PVP-TiO2 (CATP), for removal of bovine serum albumin (BSA) were prepared by using phase inversion process. The influences of PVP and TiO2 on the preparation of phase inverted cellulose acetate (CA) ultrafiltration membrane were explored in terms of morphology study, equilibrium water content (EWC), hydraulic resistance, permeability performance, hydrophilicity, and thermal stability. After the introduction of PVP and TiO2 to the ternary (polymer-solvent-non-solvent) system, the formations of finger-like structures and macro-voids were reduced significantly. An improvement in porosity, average pore size, and hydrophilic nature of the CA membranes were detected after the introduction of PVP and TiO2 into the polymer matrix. The interaction between TiO2 and CA was confirmed and the degradation temperature of the CA membrane was significantly improved. BSA protein removal efficiency, anti-fouling performance, and recycling potential of the UF membranes were investigated. The CATP membrane (10.5 wt % CA: 4 wt % PVP: 2 wt % TiO2) has displayed high BSA removal efficiency and flux recovery ratios (NFR) with enhanced anti-fouling performances for the three fouling/rinsing cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Development of electrically insulating CaO coatings

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Reed, C.B.; Uz, M.; Rink, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    A systematic study has been initiated to develop electrically insulating CaO coatings by vapor phase transport and by in-situ formation in a liquid Li environment. Several experiments were conducted in vapor transport studies with variations in process temperature, time, specimen location, specimen surface preparation, and pretreatment. Several of the coatings obtained by the method exhibited Ca concentration in the range of 60--95 wt.% on the surface. However, coating thickness has not been very uniform among several samples exposed in the same run or even within the same sample. The coatings developed in these early tests degraded after 24 h exposure to Li at 500 C. Additional experiments are underway to develop better-adhering and more dense coatings by this method. A program to develop in-situ CaO coatings in Li has been initiated, and the first set of capsule tests at 800 C in three different Li-Ca mixtures will be completed in early July. Specimens included in the run are bare V-4Cr-4Ti alloy, specimens with a grit-blasted surface and O-precharged in 99.999% Ar, polished specimens precharged in a 99.999% Ar and 5000 ppm O{sub 2}-N{sub 2} mixture, and prealuminized V-5Cr-5Ti alloy preoxidized in a 5000 ppm O{sub 2}-N{sub 2} mixture. Additional experiments at lower temperatures are planned.

  6. BaTiO3-based piezoelectrics: Fundamentals, current status, and perspectives

    Science.gov (United States)

    Acosta, M.; Novak, N.; Rojas, V.; Patel, S.; Vaish, R.; Koruza, J.; Rossetti, G. A.; Rödel, J.

    2017-12-01

    We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these materials are presented.

  7. Theoretical study of stability and superconductivity of ScHn (n =4 -8 ) at high pressure

    Science.gov (United States)

    Qian, Shifeng; Sheng, Xiaowei; Yan, Xiaozhen; Chen, Yangmei; Song, Bo

    2017-09-01

    The synthesis of hydrogen sulfides, with the potential of high-temperature superconductivity, was recently proposed at high Tc = 203 K. It motivated us to employ an ab initio approach for the predictions of crystal structures to find the stable scandium hydrides. In addition to the earlier predicted three stoichiometries of ScH, ScH2, and ScH3, we identify three other metallic stoichiometries of ScH4, ScH6, and ScH8, which show superconductivity at significantly higher temperatures. The phases of ScH4 and ScH6, whose stability does not require extremely high pressures (containing exotic quasimolecular H2 arrangements. The present electron-phonon calculations revealed the superconductive potential of ScH4 and ScH6 with estimated Tc of 98 K and 129 K at 200 GPa and 130 GPa, respectively. The superconductivity of ScHn stems from the large electron-phonon coupling associated with the wagging, bending, and intermediate-frequency modes attributed mainly to the hydrogen atoms.

  8. Omamoodi ime - ilmunud on eesti-läti sõnaraamat / Lembit Vaba

    Index Scriptorium Estoniae

    Vaba, Lembit 1945-

    2015-01-01

    Arvustus: Igauņu-latviešu vārdnīca / Latviešu valodas aģentūra ; sastādītāji: Valts Ernštreits, Marika Muzikante, Maima Grīnberga = Eesti-läti sõnaraamat / Läti keele agentuur ; koostajad: Valts Ernštreits, Marika Muzikante, Maima Grīnberga. Rīga ; Tallinn : Eesti Keele Sihtasutus, 2015

  9. Synthesis of High-Temperature Self-lubricating Wear Resistant Composite Coating on Ti6Al4V Alloy by Laser Deposition

    Science.gov (United States)

    Luo, Jian; Liu, Xiu-Bo; Xiang, Zhan-Feng; Shi, Shi-Hong; Chen, Yao; Shi, Gao-Lian; Wu, Shao-Hua; Wu, Yu-Nan

    2015-05-01

    Laser deposition was adopted to prepare novel Ni-based solid solution (γ-NiCrAlTi)/ TiC/α-Ti/CaF2 high-temperature self-lubricating wear resistant composite coating on Ti6Al4V alloy. Microstructure, micro-hardness, wear behavior, and counter-body effect of the coating were investigated systematically. It can be seen that the coating mainly consists of γ-NiCrAlTi, TiC, α-Ti, and small fine CaF2 particles. Average micro-hardness of the coating is 1023 HV0.3, which is about three-factor higher than that of Ti6Al4V substrate (380 HV0.3). The friction coefficient and wear rate of the coating decrease at all test temperatures to different extents with respect to the substrate. The improvement in wear resistance is believed to be the combined effects of the γ-NiCrAlTi solid solution, the dominating anti-wear capabilities of the reinforced TiC carbides, and the self-lubricating property of CaF2.

  10. LOCAL COLLISION SIMULATION OF AN SC WALL USING ENERGY ABSORBING STEEL

    Directory of Open Access Journals (Sweden)

    CHUL-HUN CHUNG

    2013-08-01

    Full Text Available This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

  11. Preparation and characterization of Sc doped MgB2 wires

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Burdusel, M.

    2016-01-01

    The in-situ technique was used to manufacture scandium (Sc) doped MgB2 wires in a composite Cu–Nb sheath. After reaction at 700 °C, at most 1 at.% Mg was replaced by Sc in the MgB2 phase, without significant influence on its superconducting transition temperature. For higher Sc concentrations in ...... of the precursor powders revealed by DTA measurements than to actual doping. The best performance was obtained in a wire with Mg:Sc = 0.995_0.005 atomic ratio.......The in-situ technique was used to manufacture scandium (Sc) doped MgB2 wires in a composite Cu–Nb sheath. After reaction at 700 °C, at most 1 at.% Mg was replaced by Sc in the MgB2 phase, without significant influence on its superconducting transition temperature. For higher Sc concentrations...

  12. Influence of Sc on Microstructure and Mechanical Properties of High Zn-Containing Mg Alloy

    Directory of Open Access Journals (Sweden)

    Lidong Wang

    2014-01-01

    Full Text Available Microstructures and mechanical properties of Mg-11Zn and Mg-11Zn-1Sc (wt% alloys were investigated. The main secondary phase of Mg-11Zn and Mg-11Zn-1Sc alloys is MgZn2 phase. Rare earth Sc element is an effective grain refiner and the grain size of Mg-11Zn-1Sc alloy is greatly refined. The mechanical properties of the Mg-11Zn alloy were greatly improved with incorporation of 1 wt% Sc, especially for the elevated temperature strength. Such mechanical property enhancement is ascribed to the refinement and pinning mechanism of high heat-resistant Sc and Sc-containing intermetallic particles in Mg alloy.

  13. Performance Analysis of OFDM 60GHz System and SC-FDE 60GHz System

    Directory of Open Access Journals (Sweden)

    Han Xueyan

    2016-01-01

    Full Text Available In this paper, the performance of 60GHz wireless communication system with SC and OFDM is studied, the models of OFDM 60GHz system and SC 60GHz frequency domain equalization (SC-FDE system are established, and the bit error rate (BER performance of OFDM 60GHz system and SC-FDE 60GHz system in 802.15.3c channels is compared. The simulation results show that SC-FDE 60GHz system has a slight advantage over OFDM system in line-of-sight (LOS channels, while OFDM 60GHz system has a slight advantage over SC-FDE system in non-line-of-sight (NLOS channels. For 60GHz system, OFDM 60GHz system has a slight advantage over SC-FDE system in overcoming multipath fading, but the performance of both is close whether in the LOS or NLOS case.

  14. Tribological behavior and wear mechanisms of TiN/TiCN/TiN multilayer coatings

    Science.gov (United States)

    Su, Y. L.; Kao, W. H.

    1998-10-01

    This work employs the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN⇔⇔N, and sequenced TiN⇔CN⇔N multilayer coatings with variable individual TiN-layer and TiCN-layer thicknesses on tungsten carbide disks and inserts. Also investigated are the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk, line-contact wear mode and ball-on-disk, point-contact wear mode through SRV reciprocating wear tests. Actual milling tests identify wear performance. Experimental results indicate that the coating with a total thickness of 7 Μm and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. No-tably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.

  15. Local-moment formation and metal–nonmetal transition in Ca1 ...

    Indian Academy of Sciences (India)

    temperature dependence of resistivity shows no resistance-minimum in these systems. 3. Discussion. 3.1 Phase diagrams of Ca1−x Yx VO3 and Ca1−x Yx TiO3. In these systems, it is well-known that the electron correlation increases with increasing d electron number and the systems change from a metal to a magnetic ...

  16. Topological organization of CA3-to-CA1 excitation.

    Science.gov (United States)

    Hongo, Yoshie; Ogawa, Koichi; Takahara, Yuji; Takasu, Keiko; Royer, Sebastien; Hasegawa, Minoru; Sakaguchi, Gaku; Ikegaya, Yuji

    2015-09-01

    The CA1-projecting axons of CA3 pyramidal cells, called Schaffer collaterals, constitute one of the major information flow routes in the hippocampal formation. Recent anatomical studies have revealed the non-random structural connectivity between CA3 and CA1, but little is known regarding the functional connectivity (i.e. how CA3 network activity is functionally transmitted downstream to the CA1 network). Using functional multi-neuron calcium imaging of rat hippocampal slices, we monitored the spatiotemporal patterns of spontaneous CA3 and CA1 burst activity under pharmacological GABAergic blockade. We found that spatially clustered CA3 activity patterns were transformed into layered CA1 activity sequences. Specifically, synchronized bursts initiated from multiple hot spots in CA3 ensembles, and CA1 neurons located deeper in the pyramidal cell layer were recruited during earlier phases of the burst events. The order of these sequential activations was maintained across the bursts, but the sequence velocity varied depending on the inter-burst intervals. Thus, CA3 axons innervate CA1 neurons in a highly topographical fashion. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  17. Synthesis of TiO{sub 2} sol in a neutral solution using TiCl{sub 4} as a precursor and H{sub 2}O{sub 2} as an oxidizing agent

    Energy Technology Data Exchange (ETDEWEB)

    Sasirekha, Natarajan; Rajesh, Baskaran [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China); Chen, Yu-Wen, E-mail: ywchen@cc.ncu.edu.t [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China)

    2009-11-02

    Nanosize TiO{sub 2} thin film on glass substrate was obtained through dip-coating method using TiO{sub 2} sol. Suspended nanosize TiO{sub 2} sols with anatase structure in aqueous solution were synthesized by sol-gel method using TiCl{sub 4} as a precursor. TiCl{sub 4} was reacted with an aqueous solution of NH{sub 4}OH to form Ti(OH){sub 4}, and H{sub 2}O{sub 2} was then added to form peroxo titanic acid. It was further heated in water and converted to TiO{sub 2}. The effects of the preparation parameters, viz., pH value of the Ti(OH){sub 4} gel, concentration of H{sub 2}O{sub 2}, and heating temperature and time, on the properties of the TiO{sub 2} sol were investigated. The materials were characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The results showed that the primary TiO{sub 2} particles were rhombus with the major axis ca. 10 nm and minor axis ca. 4 nm, and were in anatase structure. The sol was excellent in dispersibility and was stable in neutral and even slight basic conditions for at least 2 years without causing agglomeration. The best preparation condition was optimized with the pH value of Ti(OH){sub 4} gel at 8, H{sub 2}O{sub 2}/TiO{sub 2} mole ratio of 2, and heating at 97 {sup o}C for 8 h. The transparent adherent TiO{sub 2} film on glass substrates exhibits strong hydrophilicity after illuminating with ultraviolet light and it can be used as an efficient photocatalyst.

  18. Conceptual design of the TPF-O SC buses

    Science.gov (United States)

    Purves, Lloyd R.

    2007-09-01

    The Terrestrial Planet Finder - Occulter (TPF-O) mission has two Spacecraft (SC) buses, one for a formation-flying occulter and the other for a space telescope. These buses supply the utilities (support structures, propulsion, attitude control, power, communications, etc) required by the payloads: a deployable shade for the occulter and a telescope with instruments for the space telescope. Significant requirements for the occulter SC bus are to provide the large delta V required for the slewing maneuvers of the occulter and communications for formation flying. The TPF-O telescope SC bus shares some key features of the one for the Hubble Space Telescope (HST) in that both support space telescopes designed to observe in the visible to near infrared range of wavelengths with comparable primary mirror apertures (2.4 m for HST, 2.4 - 4.0 m for TPF-O). Significant differences from HST are that 1) the TPF-O telescope is expected to have a Wide Field Camera (WFC) that will have a Field of View (FOV) large enough to provide fine guidance, 2) TPF-O is designed to operate in an orbit around the Sun-Earth Lagrange 2 (SEL2) point which requires TPF-O (unlike HST) to have a propulsion system, and 3) the velocity required for reaching SEL2 and the limited capabilities of affordable launch vehicles require both TPF-O elements to have compact, low-mass designs. Additionally, it is possible that TPF-O may utilize a modular design derived from that of HST to allow robotic servicing in the SEL2 orbit.

  19. Study of the gradual interface between hydroxyapatite thin films PLD grown onto Ti-controlled sublayers

    Energy Technology Data Exchange (ETDEWEB)

    Grigorescu, S. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania)], E-mail: sorin.grigorescu@inflpr.ro; Carrado, A.; Ulhaq, C.; Faerber, J. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); Ristoscu, C.; Dorcioman, G.; Axente, E. [National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania); Werckmann, J. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg (France); Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, Laser Department, PO Box MG-36, 077125 Bucharest (Romania)

    2007-12-15

    Hydroxyapatite thin films were grown on layered structures by Pulsed Laser Deposition with the goal of investigating the interface of the ceramic film with the substrate. The latter consisted of Si/TiN/Ti sandwich structures. This multilayer substrate was also prepared by laser ablation earlier in the same experimental session. This particular type of structure was chosen in order to induce the in situ growth of hydroxyapatite directly onto freshly deposited Ti. We tried this way to avoid previous direct Ti exposure to air, hence its oxidation. The subsequent depositions of multilayers were performed with the aid of a carousel multi-target system mounted inside the irradiation chamber. This allowed for selecting in order the respective TiN, Ti and HA targets without opening the chamber between individual depositions. X-ray diffractometry, transmission electron microscopy and selected area electron diffractometry studies revealed the formation at the interface of a transition complex phase, 2 to 25 nm thick, consisting of a mixture of TiO{sub 2} and CaP phase. The specific growth of TiN and Ti phases was also investigated.