WorldWideScience

Sample records for service 0-5 6-12

  1. 28 CFR 0.5 - Attorney General.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Attorney General. 0.5 Section 0.5... Attorney General § 0.5 Attorney General. The Attorney General shall: (a) Supervise and direct the administration and operation of the Department of Justice, including the offices of U.S. Attorneys and U.S...

  2. Home Economics/Health Grades 6-12. Program Evaluation.

    Science.gov (United States)

    Des Moines Public Schools, IA. Teaching and Learning Div.

    Home economics programs are offered to students in grades 6-12 in the Des Moines INdependent Community School District (Iowa). Programs at the middle school level are exploratory, leading to occupational training in family and consumer science, child care, food service, and textile and fashion arts at the high school level. Health education…

  3. Aquaporins 6-12 in the human eye

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Bek, Toke; Holm, Lars

    2012-01-01

    Purpose: Aquaporins (AQPs) are widely expressed and have diverse distribution patterns in the eye. AQPs 0-5 have been localized at the cellular level in human eyes. We investigated the presence of the more recently discovered AQPs 6-12 in the human eye. Methods: RT-PCR was performed on fresh tissue...... from two human eyes divided into the cornea, corneal limbus, ciliary body and iris, lens, choroid, optic nerve, retina and sclera. Each structure was examined to detect the mRNA of AQPs 6-12. Twenty-one human eyes were examined using immunohistochemical and immunofluorescence techniques to determine...... was detected in the corneal epithelium, corneal endothelium, trabecular meshwork endothelium, ciliary epithelia, lens epithelium, the inner and outer limiting membrane of the retina, the retinal pigment epithelium and the capillary endothelium of all parts of the eye. AQP9 immunolabelling was detected...

  4. Microstructural and electrical properties of (La0.5-xPrxBa0.5)(Mn0.5Ti0.5)O3 perovskite

    International Nuclear Information System (INIS)

    Nor Hayati Alias; Abdul Halim Shaari; Wan Mohd Daud Wan Yusoff; Che Seman Mahmood

    2009-01-01

    Full text: A single phase new perovskite based titanio-manganite (La 0.5-x Pr x Ba 0.5 )(Mn 0.5 Ti 0.5 )O 3 has been successfully prepared by ceramic C. The concentration of solid-state technique at sintering temperature of 1300 Pr (Praseodymium), x, in molar proportion in A site has been varied as x = 0.0, 0.2 and 0.02. Analysis has been carried out to determine the electrical properties of the synthesized material at frequency of 1 MHz and at temperature range between 25 to 200 degree Celsius. It is found that Pr addition promoted liquid sintering diffusion, porosity and agglomeration formation at 1300 degree Celsius. Dual relaxation is observed in unsubstituted Pr sample x = 0 and high Pr substituted sample x=0.2. This phenomenon was a combinational contribution from a quasi dc (QDC) low frequency dispersion and two cole-cole relaxational response. While low concentrated Pr substituted sampled x=0.02 shows a combinational contribution from a quasi dc (QDC) low frequency dispersion and single cole-cole relaxational response at room temperature. Pr substitution at x=0 and x=0.2 showed high dielectric values compared to low substituted sample x = 0.02. Variation of dielectric loss tangent (tan ) are observed for all samples at temperature ranged studied. (author)

  5. Magnetic behaviour of hydrogenated La_0_._5Ca_0_._5MnO_3

    International Nuclear Information System (INIS)

    Lal, Ganesh; Punia, Khushboo; Kumar, Sudhish; Jyoti; Dolia, S.N.

    2016-01-01

    The half doped manganite La_0_._5Ca_0_._5MnO_3 have attracted considerable attention owing to its complex electrical and magnetic properties. This work is focused on the effects of hydrogenation on the magnetic behaviour of La_0_._5Ca_0_._5MnO_3. For hydrogenation the La_0_._5Ca_0_._5MnO_3 sample was annealed in a hydrogen atmosphere at 600°C for 6 hours in a reduction furnace and for reducing hydrogen the sample was heated in air at 600°C for 6 hours in a chamber furnace. Room temperature X-ray diffraction studies confirmed that the hydrogenation and annealing of the sample in air does not affect the single phase orthorhombic structure of La_0_._5Ca_0_._5MnO_3. These observations indicate that magnetic behaviour of La_0_._5Ca_0_._5MnO_3. can be tailored by hydrogenation

  6. Dependence of magnetic and structural properties of Ni 0.5 M 0.5 Fe ...

    African Journals Online (AJOL)

    Ni0.5M0.5Fe2O4 (M = Co, Cu) ferrite nanoparticles were synthesized using citrate precursor method. The citrate precursor was annealed at temperatures 400oC, 450oC, 500oC and 550oC. The annealed powders were characterized using X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Observed ...

  7. Synthesis and growth mechanism of Zn0.5Cd0.5S nanohexagon dendrite

    Science.gov (United States)

    Yu, Wen; Fang, Pengfei; Wang, Shaojie

    2014-12-01

    Hierarchical Zn0.5Cd0.5S nanohexagon dendrites were synthesized by a one-step hydrothermal method. The Zn0.5Cd0.5S nanohexagon dendrites were made up of nanohexagons with a side length of about 90 nm. The nanohexagons were regularly arranged forming as embranchments which were parallel to each other along certain hexagonal directions. Furthermore, these embranchments made up primary trunks shaping as dendrites. The growth mechanism of Zn0.5Cd0.5S nanohexagon dendrites was proposed in which molecular soft template and lowest energy principle played key roles. By adjusting the composition of the reactants, a series of ZnxCd1-xS solid solutions could be obtained. The morphology of the synthesized ZnxCd1-xS depended much on the x value. The UV-vis spectra absorb edges of the ZnxCd1-xS samples continuously shifted indicating the changes of the band gap.

  8. The quinternary thiophosphate Cs0.5Ag0.5Nb2PS10

    Directory of Open Access Journals (Sweden)

    Sojeong Park

    2010-07-01

    Full Text Available The quinternary thiophosphate Cs0.5Ag0.5Nb2PS10, cesium silver tris(disulfido[tetrathiophosphato(V]diniobate(IV, has been prepared from the elements using a CsCl flux. The crystal structure is made up of ∞1[Nb2PS10] chains expanding along [010]. These chains are built up from bicapped trigonal-prismatic [Nb2S12] units and tetrahedral [PS4] groups and are linked through a linear S—Ag—S bridge, forming a two-dimensional layer. These layers then stack on top of each other, completing the three-dimensional structure with an undulating van der Waals gap. The disordered Cs+ ions reside on sites with half-occupation in the voids of this arrangement. Short [2.8843 (5 Å] and long [3.7316 (4 Å] Nb—Nb distances alternate along the chains, and anionic S22− and S2− species are observed. The charge balance of the compound can be represented by the formula [Cs+]0.5[Ag+]0.5[Nb4+]2[PS43−][S22−]3.

  9. Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

    KAUST Repository

    Atanda, Luqman A.; Balasamy, Rabindran J.; Khurshid, Alam; Al-Ali, Ali A S; Sagata, Kunimasa; Asamoto, Makiko; Yahiro, Hidenori; Nomura, Kiyoshi; Sano, Tsuneji; Takehira, Katsuomi; Al-Khattaf, Sulaiman S.

    2011-01-01

    A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived

  10. Elastic Properties of Ho0.5Er0.5 Single Crystal

    DEFF Research Database (Denmark)

    Spichkin, Yu.I.; Bohr, Jakob; Tishin, A.M.

    1996-01-01

    The results of an investigation of the Young's modulus E and the interval friction Q-1 of a Ho0.5Er0.5 single crystal in the basal plane in the temperature range 4.2-400 K are reported. The measurements were carried out by the method of flexural autovibrations of a thin sample with sound frequency...... (3 kHz). The Young's modulus at 4.2 K was measured to be 154 GPa. From the obtained data the magnetic part of the Young's modulus and the Debye temperature theta-D=375 K were calculated. The anomalies on the Young's modulus and the interval friction temperature dependencies corresponding to magnetic...

  11. Phase transitions in Fe_0_._5Co_0_._5 (110) thin films

    International Nuclear Information System (INIS)

    Ramírez-Dámaso, G.; Castillo-Alvarado, F.L.; Rojas-Hernández, E.

    2016-01-01

    In this paper, we present calculations for two second-order phase transitions in (110) Fe_0_._5Co_0_._5 thin films with 11, 15, and 19 monoatomic layers. The lattice and magnetic transitions are based on thermodynamic equilibrium considerations of the magnetic alloy. The procedure proposed by Valenta and Sukiennicki was applied to calculate the composition x(i), the lattice order parameter t(i), and the magnetic order parameter σ(i) as a function of temperature T. We confirmed that both phase transitions, lattice and magnetic, are of the second order, in accordance with experimental results in the literature. The obtained behavior of these parameters indicates their inhomogeneity due to the boundary conditions on the surfaces of the thin film.

  12. Structural characterization of layered Na0.5Co0.5Mn0.5O2 material as a promising cathode for sodium-ion batteries

    Science.gov (United States)

    Manikandan, Palanisamy; Heo, Seongwoo; Kim, Hyun Woo; Jeong, Hu Young; Lee, Eungje; Kim, Youngsik

    2017-09-01

    Layered Na0.5Co0.5Mn0.5O2 material is synthesized through a facile mixed hydroxy-carbonate route using (Co0.5Mn0.5)2(OH)2CO3 precursor and well characterized as a hexagonal layered structure under P63/mmc space group. The lattice parameters and unit cell volume (a = 2.8363 Å, c = 11.3152 Å and V = 78.83 Å3) are calculated by Rietveld refinement analysis. A flaky-bundle morphology is obtained to the layered Na0.5Co0.5Mn0.5O2 material with the hexagonal flake size ∼30 nm. Advanced transmission electron microscopic images are revealed the local structure of the layered Na0.5Co0.5Mn0.5O2 material with contrasting bright dots and faint dark dots corresponding to the Co/Mn and Na atoms. Two oxidation and reduction peaks are occurred in a cyclic voltammetric analysis corresponding to Co3+/Co4+ and Mn3+/Mn4+ redox processes. These reversible processes are attributed to the intercalation/de-intercalation of Na+ ions into the host structure of layered Na0.5Co0.5Mn0.5O2 material. Accordingly, the sodium cell is delivered the initial charge-discharge capacity 53/144 mAh g-1 at 0.5 C, which cycling studies are extended to rate capability test at 1 C, 3 C and 5C. Eventually, the Na-ion full-cell is yielded cathode charge-discharge capacity 55/52 mAh g-1 at 0.212 mA and exhibited as a high voltage cathode for Na-ion batteries.

  13. Efficacy and safety of 0.5% levobupivacaine versus 0.5% bupivacaine for peribulbar anesthesia

    Directory of Open Access Journals (Sweden)

    Pacella E

    2013-05-01

    Full Text Available Elena Pacella,1 Fernanda Pacella,1 Fabiana Troisi,2 Domenico Dell'Edera,3 Paolo Tuchetti,4 Tommaso Lenzi,1 Saul Collini21Department of Sense Organs, Faculty of Medicine and Dentistry, Rome, 2Department of Medical Surgical Sciences and Translational Medicine Sapienza, Faculty of Medicine and Psychology, Roma, University of Rome, Rome, 3Unit of Cytogenetic and Molecular Genetics, Madonna delle Grazie Hospital, Matera, 4National Institute for Health, Migration and Poverty, Rome, ItalyBackground: This randomized double-blind study examined the use of a new anesthetic agent, levobupivacaine 0.5%, which is the S(−-enantiomer of a racemic mixture of bupivacaine, for peribulbar anesthesia and compared it with racemic bupivacaine 0.5% alone or in combination with hyaluronidase 10 IU/mL.Methods: A total of 160 patients undergoing ophthalmic surgery were randomized into four groups (n = 40 each to receive inferotemporal peribulbar injection of levobupivacaine 0.5% (group L, racemic bupivacaine 0.5% (group B, levobupivacaine + hyaluronidase 10 IU/mL (group LH, or racemic bupivacaine + hyaluronidase 10 IU/mL (group BH by two anesthetists and two ophthalmologists in a ratio of 25% each. Ocular akinesia and orbicularis oculi function were evaluated using a three-point scale; a value < 5 points was considered as requiring surgery, and movements were re-evaluated the day following surgery to confirm regression of the block.Results: The time to onset (12 ± 2.6 minutes versus 13 ± 2.8 minutes and duration of anesthesia (185 ± 33.2 minutes versus 188 ± 35.7 minutes were similar between groups L and B. Complete akinesia (score 0 was obtained more frequently when hyaluronidase was used in addition to the anesthetic, with occurrences of 72.5% versus 57.5% in group LH versus L, respectively, and 67.5% versus 45% in group BH versus B. Moderate hypotension (<30% of baseline was observed in four patients (10% in group L, two (5.0% in group B, one (2.5% in group LH

  14. Enhancement in electrical and magnetic properties with Ti-doping in Bi0.5La0.5Fe0.5Mn0.5O3

    Science.gov (United States)

    Singh, Rahul; Gupta, Prince Kumar; Kumar, Shiv; Joshi, Amish G.; Ghosh, A. K.; Patil, S.; Chatterjee, Sandip

    2017-04-01

    In this investigation, we have synthesized Bi0.5La0.5Fe0.5Mn0.5-xTixO3 (where x = 0 and 0.05) samples. The Rietveld refinement of X-ray diffraction (XRD) patterns shows that the systems crystallize in the orthorhombic phase with the Pnma space group. The observed Raman modes support the XRD results. The appearance of prominent A1-3 and weak E-2 modes in Bi0.5La0.5Fe0.5Mn0.45Ti0.05O3 indicates the presence of chemically more active Bi-O covalent bonds. Ferromagnetism of Bi0.5La0.5Fe0.5Mn0.5O3 is enhanced by Ti doping at the Mn-site, indicating that these particular samples might be interesting for device applications.

  15. Formation of perovskite-type compounds La0.5Ca0.5Mn1-xTixO3 (0≤x≤0.5)

    International Nuclear Information System (INIS)

    Wang, K.-Y.; Arcas, J.; Chen, D.-X.; Hernando, A.

    1997-01-01

    A series of perovskite-type compounds La 0.5 Ca 0.5 Mn 1-x Ti x O 3 is prepared by solid-state reaction. It is found that a single-phase tetragonal structure can be obtained for x≤0.5; the lattice parameters increase and magnetization at μ 0 H=0.2. T decreases with increasing x. (orig.)

  16. Synthesis and characterization of the novel rare earth orthophosphates Y0.5Er0.5PO4 and Y0.5Yb0.5PO4

    International Nuclear Information System (INIS)

    Schildhammer, Daniel; Petschnig, Lucas L.; Fuhrmann, Gerda; Heymann, Gunter; Schottenberger, Herwig; Huppertz, Hubert; Tribus, Martina

    2016-01-01

    The new mixed rare earth (RE) orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 were synthesized by a classical solid state reaction in an electrical furnace at 1200 C. As starting materials, the corresponding rare earth oxides and diammonium hydrogen phosphate were used. The powder diffraction analyses revealed that the new compounds Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in a zircon-type structure being isostructural with the rare earth orthophosphate YPO 4 . Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 crystallize in the tetragonal space group I4 1 /amd (no. 141) with four formula units in the unit cell. The structural parameters based on Rietveld refinements are a = 687.27(2), c = 601.50(2) pm, V = 0.28412(1) nm 3 , R p = 0.0143, and R wp = 0.0186 (all data) for Y 0.5 Er 0.5 PO 4 and a = 684.61(2), c = 599.31(2) pm, V = 0.28089(2) nm 3 , R p = 0.0242, and R wp = 0.0313 (all data) for Y 0.5 Yb 0.5 PO 4 . Furthermore, the structure of Y 0.5 Er 0.5 PO 4 was refined from single-crystal X-ray diffraction data: a = 687.78(5), c = 601.85(4) pm, V = 0.28470(5) nm 3 , R 1 = 0.0165, and wR 2 = 0.0385 (all data). In both compounds, the rare earth metal ions are eightfold coordinated by oxygen atoms, forming two unique interlocking tetrahedra with two individual RE-O distances. The tetrahedral phosphate groups [PO 4 ] 3- are slightly distorted in both compounds. The individual rare earth ions share a common position (Wyckoff site 4a). The presence of two rare earth ions in the structures of the new orthophosphates Y 0.5 Er 0.5 PO 4 and Y 0.5 Yb 0.5 PO 4 was additionally confirmed by single-crystal EDX spectroscopy revealing a ratio of 1:1.

  17. Magnetic and magnetocaloric properties of the alloys Mn2-xFexP0.5As0.5 (0⩽x⩽0.5)

    Science.gov (United States)

    Gribanov, I. F.; Golovchan, A. V.; Varyukhin, D. V.; Val'kov, V. I.; Kamenev, V. I.; Sivachenko, A. P.; Sidorov, S. L.; Mityuk, V. I.

    2009-10-01

    The results of investigations of the magnetic and magnetocaloric properties of alloys from the system Mn2-xFexP0.5As0.5 (0⩽x⩽0.5) are presented. The magnetization measurements are performed in the temperature interval 4.2-700K in magnetic fields up to 8T. The entropy changes ΔS with the magnetic field changing from 0 to 2, 4, 5, and 8T are determined from the magnetization isotherms obtained near temperatures of the spontaneous appearance of the ferromagnetic state (TC,TAF -FM1), and the curves ΔS(T0) are constructed. It is found that TC and TAF-FM1 decrease monotonically with increasing manganese concentration and that the ferromagnetic phase is completely suppressed in Mn1.5Fe0.5P0.5As0.5. It is found that the concentration dependences of the maximum entropy jump (and the corresponding cold-storage capacity) and the magnitudes of the ferromagnetic moment of the unit cell with maxima for x =0.9 and 0.8 show extremal behavior. The data obtained are compared with the ferromagnetic moments calculated from first principles by the Korringa-Kohn-Rostoker method using the coherent-potential approximation (KKR-CPA)—the discrepancy for 0.5⩽x⩽0.7 is attributed to the appearance of an antiferromagnetic component of the magnetic structure. It is concluded that the alloys Mn2-xFexP0.5As0.5 have promise for use in magnetic refrigerators operating at room temperature.

  18. Structire ordering effect on dielectric properties of PbInsub(0.5)Nbsub(0.5)Osub(3) crystals

    International Nuclear Information System (INIS)

    Turik, A.V.; Kupriyanov, M.F.; Zhestkov, B.F.

    1985-01-01

    Results are presented of dielectric and X-ray diffraction investigations into the PbZnsub(0.5)Nbsub(0.5)Osub(3) monocrystals of PbBsub(0.5)'Bsub(0.5)''Osub(3) series (B'=ScIn, B''=Nb, Ta) annealed during 5 hours at 500 deg C. It is shown that ordering in the B'-cation position in crystals influences the character of alternation of phases and physical properties. The PbInsub(0.5)Nbsub(0.5)Osub(3) crystals may be either in rhombohedral ferro- or zhombic antiferroelectric phases depending on thermal prehistory

  19. Multiaxial creep of fine grained 0.5Cr-0.5Mo-0.25V and coarse grained 1Cr-0.5Mo steels

    International Nuclear Information System (INIS)

    Browne, R.J.; Flewitt, P.E.J.; Lonsdale, D.

    1991-01-01

    To explore the multiaxial creep response of materials used for electrical power generating plant, two steels, a fine grained 0.5Cr-0.5Mo-0.25V steel in a normalised and tempered condition with high creep ductility and a coarse grained 1Cr-0.5Mo steel in a quenched and tempered condition with low uniaxial creep ductility, have been selected. A range of multiaxial stress testing techniques which span the stress states that would allow identification of any technique dependent variables has been used. The deformation and failure of the normalised and tempered 0.5Cr-0.5Mo-0.25V steel for a range of multiaxial test techniques and, therefore, stress states may be described by an equivalent stress criterion. The results from the multiaxial tests carried out on the fully bainitic 1Cr-0.5Mo steel show that the multiaxial stress rupture criterion (MSRC) varies with stress state; at high triaxiality (notch), it is controlled by the maximum principal stress, whereas at low triaxiality (shear) it is dependent on both maximum principal stress and equivalent stress. Furthermore, a simple description of stress state based on maximum principal and equivalent stress does not define this uniquely, since the MSRC derived from uniaxial and torsion testing does not describe the failure of notch, tube, or double shear tests. (author)

  20. Selective Etching of Silicon in Preference to Germanium and Si0.5Ge0.5.

    Science.gov (United States)

    Ahles, Christopher F; Choi, Jong Youn; Wolf, Steven; Kummel, Andrew C

    2017-06-21

    The selective etching characteristics of silicon, germanium, and Si 0.5 Ge 0.5 subjected to a downstream H 2 /CF 4 /Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and Si 0.5 Ge 0.5 , with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/Si 0.5 Ge 0.5 , the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick C x H y F z layer formed by the H 2 /CF 4 /Ar plasma on Si, Ge, and Si 0.5 Ge 0.5 . The data are consistent with the less exothermic reaction of fluorine radicals with Ge or Si 0.5 Ge 0.5 being strongly suppressed by the C x H y F z layer, whereas, on Si, the C x H y F z layer is not sufficient to completely suppress etching. Replacing H 2 with D 2 in the feed gas resulted in an inverse kinetic isotope effect (IKIE) where the Si and Si 0.5 Ge 0.5 etch rates were increased by ∼30 times with retention of significant etch selectivity. The use of D 2 /CF 4 /Ar instead of H 2 /CF 4 /Ar resulted in less total carbon deposition on Si and Si 0.5 Ge 0.5 and gave less Ge enrichment of Si 0.5 Ge 0.5 . These results are consistent with the selectivity being due to the differential suppression of etching by an angstrom-scale carbon layer.

  1. Annealing-induced near-surface ordering in disordered Ga0.5In0.5P

    International Nuclear Information System (INIS)

    Luo, J.S.; Olson, J.M.; Wu, M.

    1995-01-01

    Most samples of Ga 0.5 In 0.5 P grown by metalorganic chemical vapor deposition (MOCVD) on (001)-like surfaces are partially ordered and exhibit distinctive reflectance difference spectral (RDS) features associated with the anisotropic properties of the ordered bulk structure. It is known that the ordering is not a ground-state property of the bulk but is surface-induced during growth. On the other hand, Ga 0.5 In 0.5 P grown by liquid-phase epitaxy (LPE) is completely disordered, and it has been shown that its RD spectrum is essentially featureless. In this article, we present a study of the effects of annealing (in a PH 3 /H 2 atmosphere) on LPE-grown Ga 0.5 In 0.5 P using ex situ and in situ RDS. The annealing temperatures and times used in this study (650 degree C and tens of minutes) have virtually no effect on the bulk optical or structural properties of MOCVD-grown Ga 0.5 In 0.5 P. For LPE-grown Ga 0.5 In 0.5 P, we find that annealing induces bulk-like RDS features at both E 0 and E 1 with line shapes similar to those observed for MOCVD-grown ordered Ga 0.5 In 0.5 P. These bulk-like spectral features are, however, due to near-surface reconstruction of Ga and In because they are effectively quenched by exposure to air. Also, the E 0 feature becomes sharper and both the E 0 and the E 1 features red-shift as the annealing process is prolonged. This indicates that this reconstruction is kinetically limited, presumably by the slow interdiffusion of Ga and In necessary to achieve the ordered bulk-like structure. copyright 1995 American Vacuum SocietyGa 0.5 In 0.5 P

  2. Dark-red-emitting CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots: Effect of chemicals on properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping, E-mail: mse_yangp@ujn.edu.cn; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

    2013-08-15

    CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling.

  3. Dark-red-emitting CdTe0.5Se0.5/Cd0.5Zn0.5S quantum dots: Effect of chemicals on properties

    International Nuclear Information System (INIS)

    Yang, Ping; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

    2013-01-01

    CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe 0.5 Se 0.5 /Cd 0.5 Zn 0.5 S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling

  4. Freeze drying synthesis of LiNi0.5Mn0.5O2 cathode materials

    International Nuclear Information System (INIS)

    Shlyakhtin, O.A.; Yoon, Young Soo; Choi, Sun Hee; Oh, Young-Jei

    2004-01-01

    The influence of several processing conditions on the phase formation and electrochemical performance of LiNi 0.5 Mn 0.5 O 2 powders, obtained by freeze drying method, is studied. Thermal processing in pellets at maximum heating rate promotes better crystallographic ordering of hexagonal LiNi 0.5 Mn 0.5 O 2 and maximum capacity values irrespectively of chemical composition of the precursor. Instead, intense mechanical processing of precursors exerts considerable negative effect on the electrochemical performance. Cathode materials containing superstoichiometric amount of lithium (Li 1.3 Mn 0.5 Ni 0.5 O 2+δ ) demonstrate reversible capacity values up to 190 mAh/g between 2.5 and 4.6 V

  5. Fabrication and magnetic properties of Ni0.5Zn0.5Fe2O4 nanofibres by electrospinning

    International Nuclear Information System (INIS)

    Jun, Xiang; Xiang-Qian, Shen; Fu-Zhan, Song; Ming-Quan, Liu

    2009-01-01

    NiZn ferrite/polyvinylpyrrolidone composite fibres were prepared by sol–gel assisted electrospinning. Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres with a pure cubic spinel structure were obtained subsequently by calcination of the composite fibres at high temperatures. This paper investigates the thermal decomposition process, structures and morphologies of the electrospun composite fibres and the calcined Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres at different temperatures by thermo-gravimetric and differential thermal analysis, x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The magnetic behaviour of the resultant nanofibres was studied by a vibrating sample magnetometer. It is found that the grain sizes of the nanofibres increase significantly and the nanofibre morphology gradually transforms from a porous structure to a necklace-like nanostructure with the increase of calcination temperature. The Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres obtained at 1000 °C for 2 h are characterized by a necklace-like morphology and diameters of 100–200 nm. The saturation magnetization of the random Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres increases from 46.5 to 90.2 emu/g when the calcination temperature increases from 450 to 1000 °C. The coercivity reaches a maximum value of 11.0 kA/m at a calcination temperature of 600 °C. Due to the shape anisotropy, the aligned Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres exhibit an obvious magnetic anisotropy and the ease magnetizing direction is parallel to the nanofibre axis. (condensed matter: structure, thermal and mechanical properties)

  6. Phase formation, structure and dielectric properties of ceramics (Na0.5Bi0.5TiO3–(K0.5Na0.5NbO3–BiFeO3

    Directory of Open Access Journals (Sweden)

    G. M. Kaleva

    2016-03-01

    Full Text Available Influence of BiFeO3 (BF on phase formation, unit cell parameters, microstructure, dielectric and ferroelectric properties of solid solutions close to the morphotropic phase boundary in the (Na0.5Bi0.5TiO3–(K0.5Na0.5NbO3 system additionally modified by the low-melting KCl additives has been studied. The formation of pure perovskite structure samples decrease in the unit cell parameters and increase in the TC value stimulated by the BF addition have been revealed. It was proved that modification of compositions by small amounts of the BF and KCl additives leads to improvement of dielectric parameters.

  7. Crystal and magnetic study of the disordered perovskites Ca(Mn0.5Sb0.5)O3 and Ca(Fe0.5Sb0.5)O3

    International Nuclear Information System (INIS)

    Retuerto, M.; Martinez-Lope, M.J.; Garcia-Hernandez, M.; Munoz, A.; Fernandez-Diaz, M.T.; Alonso, J.A.

    2010-01-01

    We have investigated the double perovskites Ca 2 MSbO 6 (M = Mn, Fe) that have been prepared by solid-state reaction (M = Fe) and wet chemistry procedures (M = Mn). The crystal and magnetic structures have been studied from X-ray (XRD) and neutron powder diffraction (NPD) data. Rietveld refinements show that the crystal structures are orthorhombic (space group Pbnm) with complete disorder of M and Sb cations, so the formula should be rewritten as Ca(M 0.5 Sb 0.5 )O 3 . Due to this disorder no evidences of Jahn-Teller distortion can be observed in the MnO 6 octahedra of Ca(Mn 0.5 Sb 0.5 )O 3 , in contrast with the ordered double perovskite Sr 2 MnSbO 6 . Ca(Fe 0.5 Sb 0.5 )O 3 behaves as an antiferromagnet with an ordered magnetic moment for Fe 3+ of 1.53(4)μ B and a propagation vector k = 0, as investigated by low-temperature NPD. The antiferromagnetic ordering is a result of the high degree of Fe/Sb anti-site disorder of the sample, which originates the spontaneous formation of Fe-rich islands, characterized by the presence of strong Fe-O-Fe antiferromagnetic couplings with enough long-range coherence to produce a magnetic contribution perceptible by NPD. By contrast, the magnetic structure of Ca(Mn 0.5 Sb 0.5 )O 3 cannot be observed by low-temperature NPD because the magnitude of the ordered magnetic moments is below the detection threshold for neutrons.

  8. Liquid phase interaction in TiC0,5N0,5-TiNi-Mo and TiC0,5N0,5-TiNi-Ti-Mo

    International Nuclear Information System (INIS)

    Askarova, L.Kh; Grigorov, I.G.; Zajnulin, Yu.G.

    1998-01-01

    Using the methods of X ray diffraction analysis, electron microscopy and X ray spectrum microanalysis a study was made into specific features of phase and structure formation in alloys TiC 0,5 N 0,5 -TiNi-Mo and TiC 0,5 N 0,5 -TiNi-Mo in the presence of a liquid phase at temperatures of 1380-1600 deg C. It is revealed that the physical and chemical processes taking place during the liquid-phase sintering result in the formation of a three-phase alloy consisting of nonstoichiometric titanium carbonitride TiC 0.5-x N 0.5-x , a molybdenum base solid solution of titanium, nickel and carbon Mo(Ti, Ni, C) and one of two intermetallic compounds, either TiNi or Ni 3 Ti. Metallic element concentration in individual phase constituents of the alloy is determined by means of X ray spectrum microanalysis

  9. Distribution of relaxation times in (KBr)/sub 0.5/(KCN)/sub 0.5/

    International Nuclear Information System (INIS)

    Birge, N.O.; Jeong, Y.H.; Nagel, S.R.; Bhattacharya, S.; Susman, S.

    1984-01-01

    Measurements of the dielectric response of (KBr)/sub 0.5/(KCN)/sub 0.5/ covering nine decades of frequency are reported. We have shown how the relaxation times proliferate as the temperature is lowered. The anomalously wide distribution of relaxation times can be generated from a Gaussian distribution of energy barriers. As temperature is decreased not only does the spread of relaxation times increase, but more importantly the width of the distribution of activation energies itself increases

  10. Synthesis and characterization of superionic (LiBr)_0_._5(AlSiO)_0_._5

    International Nuclear Information System (INIS)

    Aziz K Jahja; Safei Purnama

    2010-01-01

    Materials of LiBr silicate aluminum ionic conductor have been prepared by powder metallurgy method in which 0.5 mole of LiBr powder is mixed with about 0.5 mole silicate aluminum in liquid medium of aquadest. After mixing and homogenization, the samples are dried, compacted and heated at 600 °C for 1 hour. Characterization of materials structure was carried out by X-Ray diffraction, ionic conductivity was measured by LCR meter with frequency range of 10"-"1 to 10"5 Hz at room temperature. Results of measurement show the (LiBr)_0_._5(AlSiO)_0_._5 conductor has the structure of both LiBr and of silicate aluminum. (LiBr)_0_._5(AlSiO)_0_._5 has the highest ionic conductivity in the order of 10"-"3 S.cm"-"1 while the ionic conductivity of LiBr is found to be about 10"-"4 S.cm"-"1 and that of silicate aluminum is about 10"-"6 S.cm"-"1, all measured at room temperature. (author)

  11. Structure-property correlation in PrFe0.5Mn0.5O2.95

    International Nuclear Information System (INIS)

    Ganeshraj, C.; Santhosh, P.N.; Sharma, Neetika; Das, A.; Mahendiran, R.

    2014-01-01

    PrFe 0.5 Mn 0.5 O 2.95 (PFMO) prepared by the conventional ceramic route is analyzed using a variety of techniques to understand the structural, magnetic and electrical properties. From the Neutron diffraction data it is concluded that PFMO crystallizes in an orthorhombic structure (Pnma). The magnetic structure can be represented as Γ 2 : C x G y F z , in Bertaut's notation, which has a net ferromagnetic moment along z-direction, and the spin component along x-direction (C x ) is found to be negligibly small. The canted G-type antiferromagnet PrFe 0.5 Mn 0.5 O 2.95 shows an enhanced Jahn-Teller (JT) distortion below 150 K (T*). The resistivity of the grains can be described by variable range hopping (VRH) between the localized states and there is a dominant grain boundary contribution to dc resistivity, below T*. Above T*, the total dc resistivity follows small polaron hopping (SPH) conduction. By means of complex impedance analysis, it is found that the observed giant dielectric response can be ascribed to Maxwell-Wagner polarization at the grain/grain boundary interfaces. Despite the low concentration of JT active Mn 3+ ions, our result indicates an important role of JT effect on physical properties of PrFe 0.5 Mn 0.5 O 2.95 . (author)

  12. Atomistic simulations of nanocrystalline U0.5Th0.5O2 solid solution under uniaxial tension

    Directory of Open Access Journals (Sweden)

    Hongxing Xiao

    2017-12-01

    Full Text Available Molecular dynamics simulations were performed to investigate the uniaxial tensile properties of nanocrystalline U0.5Th0.5O2 solid solution with the Born–Mayer–Huggins potential. The results indicated that the elastic modulus increased linearly with the density relative to a single crystal, but decreased with increasing temperature. The simulated nanocrystalline U0.5Th0.5O2 exhibited a breakdown in the Hall–Petch relation with mean grain size varying from 3.0 nm to 18.0 nm. Moreover, the elastic modulus of U1-yThyO2 solid solutions with different content of thorium at 300 K was also studied and the results accorded well with the experimental data available in the literature. In addition, the fracture mode of nanocrystalline U0.5Th0.5O2 was inclined to be ductile because the fracture behavior was preceded by some moderate amount of plastic deformation, which is different from what has been seen earlier in simulations of pure UO2.

  13. Magnetic properties of screen-printed (Y0.5Sm0.5)Co5 magnet arrays

    International Nuclear Information System (INIS)

    Bueno-Baques, D.; Maldonado-Chavez, L.; Hidalgo-Gonzalez, J.L.; Matutes-Aquino, J.A.; Corral-Flores, V.

    2007-01-01

    (Y 0.5 Sm 0.5 )Co 5 magnet arrays of square μdots of 300 μm were prepared by screen printing. A well controlled paste like ink prepared with the (Y 0.5 Sm 0.5 )Co 5 nanoparticles and a mixture of organic solvent and polymer was used to print different pattern arrays. (Y 0.5 Sm 0.5 )Co 5 nanoparticles were obtained by mechanical milling starting from arc melted ingots and heat treated in Ar atmosphere. Two different heat treatment were considered, resulting in powders with different magnetic properties. The microstructure of the magnet arrays was studied by scanning electron microscopy (SEM). An isotropic homogeneous distribution of the nanoparticles inside the μdots was observed. The final shape of the μdots in the array was found to be highly dependent on the squeeze pressure and speed over the mesh. Magnetic properties were studied by pulsed field magnetometry and vibrating sample magnetometry at room temperature. The micro size arrays showed lower saturation magnetization and a slightly increase in the coercive field. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Stable Ferroelectric Behavior of Nb-Modified Bi0.5K0.5TiO3-Bi(Mg0.5Ti0.5)O3 Lead-Free Relaxor Ferroelectric Ceramics

    Science.gov (United States)

    Zaman, Arif; Malik, Rizwan Ahmed; Maqbool, Adnan; Hussain, Ali; Ahmed, Tanveer; Song, Tae Kwon; Kim, Won-Jeong; Kim, Myong-Ho

    2018-03-01

    Crystal structure, dielectric, ferroelectric, piezoelectric, and electric field-induced strain properties of lead-free Nb-modified 0.96Bi0.5K0.5TiO3-0.04Bi(Mg0.5Ti0.5)O3 (BKT-BMT) piezoelectric ceramics were investigated. Crystal structure analysis showed a gradual phase transition from tetragonal to pseudocubic phase with increasing Nb content. The optimal piezoelectric property of small-signal d 33 was enhanced up to ˜ 68 pC/N with a lower coercive field ( E c) of ˜ 22 kV/cm and an improved remnant polarization ( P r) of ˜ 13 μC/cm2 for x = 0.020. A relaxor-like behavior with a frequency-dependent Curie temperature T m was observed, and a high T m around 320°C was obtained in the investigated system. This study suggests that the ferroelectric properties of BKT-BMT was significantly improved by means of Nb substitution. The possible shift of depolarization temperature T d toward high temperature T m may have triggered the spontaneous relaxor to ferroelectric phase transition with long-range ferroelectric order without any traces of a nonergodic relaxor state in contradiction with Bi0.5Na0.5TiO3-based systems. The possible enhancement in ferroelectric and piezoelectric properties near the critical composition x = 0.020 may be attributed to the increased anharmonicity of lattice vibrations which may facilitate the observed phase transition from a low-symmetry tetragonal to a high-symmetry cubic phase with a decrease in the lattice anisotropy of an undoped sample. This highly flexible (at a unit cell level) narrow compositional range triggers the enhancement of d 33 and P r values.

  15. Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

    KAUST Repository

    Atanda, Luqman A.

    2011-04-01

    A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived from hydrotalcite. The hydrotalcites prepared by co-precipitation were calcined at 550 °C to the mixed oxides with a high surface area of 150-240m2gcat-1; they were composed of Mg(Fe,Me,Al)O periclase and Mg(Me)(Fe,Al)2O4 spinel (Me = Co or Ni). Bimetallic Fe3+-Co2+ system showed a synergy, i.e., an increase in the activity, whereas Fe3+-Ni2+ bimetallic system showed no synergy. The high styrene yield was obtained on Mg 3Fe0.1Co0.4Al0.5; however, a large substitution of Fe3+ with Co2+ caused a decrease in styrene selectivity along with coking on the catalysts, due to an isolation of CoOx on the catalyst surface. The highest yield as well as the highest selectivity for styrene production was obtained at x = 0.25 at time on stream of 30 min. The coprecipitation at pH = 10.0 and the composition of Mg3Fe0.25Co0.25Al0.5 were the best for preparing the active catalyst. This is partly due to the formation of a good hydrotalcite structure. On this catalyst, the active Fe3+ species was reduced at a low temperature by the Fe3+-Co2+ bimetal formation, leading to a high activity. Simultaneously, the amount of reducible Fe3+ was the smallest, resulting in a high stability of the active Fe3+ species. It is likely that the dehydrogenation was catalyzed by the reduction-oxidation between Fe3+ and Fe2+ and that Co2+ assisted the reduction-oxidation by forming Fe 3+-Co2+ (1/1) bimetallic active species. © 2011 Elsevier B.V. All rights reserved.

  16. Crystal structure and Mössbauer effect in multiferroic 0.5BiFeO3-0.5Pb(Fe0.5Ta0.5O3 solid solution

    Directory of Open Access Journals (Sweden)

    Stoch Agata

    2017-06-01

    Full Text Available Multiferroic 0.5BiFeO3-0.5Pb(Fe0.5Ta0.5O3 solid solution is a material that exhibits ferroelectric and antiferromagnetic orderings in ambient temperature. The solid solution was obtained as a result of a conventional reaction in a solid state. The obtained material is a dense, fine-grained sinter whose surface was observed by scanning electron microscopy (SEM and stoichiometry was confirmed by energy dispersive X-ray spectroscopic (EDS analysis. According to the X-ray powder diffraction (XRD measurements, the main phase is R3c space group with admixture of Pm-3m regular phase. Small contribution of pyrochlore-like phase was also observed. Mössbauer spectroscopy suggested random distribution of Fe3+/Ta5+ cations in the B sites of ABO3 compound. Reduction of the magnetic hyperfine field with an increase in the substitution of Ta5+ in Fe3+ neighbourhood was also observed.

  17. Dielectric and piezoelectric properties of BiFeO3 modified Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 lead-free piezoelectric ceramics

    International Nuclear Information System (INIS)

    Zhou Changrong; Liu Xinyu; Li Weizhou

    2008-01-01

    The (0.82 - x)Bi 0.5 Na 0.5 TiO 3 -0.18Bi 0.5 K 0.5 TiO 3 -xBiFeO 3 (x = 0-0.07) lead-free piezoelectric ceramics were fabricated by a conventional solid-state reaction method and the effect of BiFeO 3 addition on microstructure and electrical properties of the ceramics was investigated. The specimens with x ≤ 0.05 maintained a rhombohedral-tetragonal phase coexistence and changed into a rhombohedral phase when x > 0.05 in crystal structure. The addition of BiFeO 3 caused a promoted grain growth. All the specimens reveal a low-frequency dielectric dispersion in the frequency range of 40-1 MHz. The piezoelectric constant d 33 and the electromechanical coupling factor k p show an obvious improvement by the addition of small amount of BiFeO 3 , which shows optimum values of d 33 = 170 pC/N and k p = 0.366 at x = 0.03. Contrary to the enhancement of piezoelectric properties, Q m decreases with increasing BiFeO 3 content. The mechanisms of intrinsic and extrinsic contributions to the dielectric and piezoelectric responses have been proposed. Intrinsic contributions are from the relative ion/cation shift that preserves the ferroelectric crystal structure. The remaining extrinsic contributions are from the domain-wall motion and point defects

  18. Determination of kinetic parameters in the systems Li0.5La0.5TiO3 and Li0.5La0.5TiO3/PANI by GITT (Galvanostatic intermittent titration technique)

    International Nuclear Information System (INIS)

    Pérez Cappe, Eduardo; Mosqueda Laffita, Yodalgis; Milian Pila, Carlos R.

    2008-01-01

    Full text: Oxides belonging to the family Li 3x La 2/3-x TiO 3 have been reported as materials of a high Ionic conductivity and a poor electronic conductivity at room temperature. The combination of these materials with other polymer in nature, such as polyaniline (PANI), of proven electronic properties, allows to obtain potentially applicable material in rechargeable Li. In this context the study of diffusive phenomena are of vital importance. A technical electrochemistry of intermittent rating (GITT), which combines state transient measurements and stationary, for the calculation of kinetic parameters in the Li 0.5 La 0.5 TiO 3 system and a composite comprising this oxide and PANI (Li 0.5 La 0.5 TiO 3 /PANI) in its conductive phase (emeraldine) is used in this work. Interesting considerations concerning shows the calculation of the numbers of ionic and electronic transport, necessary for the determination of coefficients of electronic dissemination. (author)

  19. Investigation on magnetoelectric behavior of (80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-CoFe2O4 particulate composites

    Science.gov (United States)

    Liu, Sheng; Yan, Shuoqing; Yao, Lingling; He, Jun; He, Longhui; Hu, Zhaowen; Huang, Shengxiang; Deng, Lianwen

    2017-12-01

    Particulate magnetoelectric (ME) ceramics constituted by (1-x)(80Bi0.5Na0.5TiO3-20Bi0.5K0.5TiO3)-xCoFe2O4 [(1-x)BNKT-xCFO] (x = 0, 0.1, 0.2, 0.3, 0.4 and 1.0) were synthesized by an powder-in-sol precursor hybrid processing method and their structure, magnetic, ferroelectric, magnetodielectric (MD) and ME properties have been investigated. Results showed that the ceramics consisted of only two chemically separated phases and had homogeneous microstructure. The introduction of CFO into BNKT matrix led to the weakening of ferroelectric and dielectric properties whereas the strengthening magnetic and MD properties. The observation of the MD effect revealed the evidence of the strain-induced ME coupling and the MD value is well scaled with M2. A maximum value of ME output of 25.07 mV/cm·Oe was achieved for the 0.7BNKT-0.3CFO composite. The improved ME response together with the linear MD effect makes the ceramics promise for use in magnetic field controllable devices or magneto-electric transducers.

  20. Dielectric properties of (K0.5Na0.5)NbO3-(Bi0.5Li0.5)ZrO3 lead-free ceramics as high-temperature ceramic capacitors

    Science.gov (United States)

    Yan, Tianxiang; Han, Feifei; Ren, Shaokai; Ma, Xing; Fang, Liang; Liu, Laijun; Kuang, Xiaojun; Elouadi, Brahim

    2018-04-01

    (1 - x)K0.5Na0.5NbO3- x(Bi0.5Li0.5)ZrO3 (labeled as (1 - x)KNN- xBLZ) lead-free ceramics were fabricated by a solid-state reaction method. A research was conducted on the effects of BLZ content on structure, dielectric properties and relaxation behavior of KNN ceramics. By combining the X-ray diffraction patterns with the temperature dependence of dielectric properties, an orthorhombic-tetragonal phase coexistence was identified for x = 0.03, a tetragonal phase was determined for x = 0.05, and a single rhombohedral structure occurred at x = 0.08. The 0.92KNN-0.08BLZ ceramic exhibits a high and stable permittivity ( 1317, ± 15% variation) from 55 to 445 °C and low dielectric loss (≤ 6%) from 120 to 400 °C, which is hugely attractive for high-temperature capacitors. Activation energies of both high-temperature dielectric relaxation and dc conductivity first increase and then decline with the increase of BLZ, which might be attributed to the lattice distortion and concentration of oxygen vacancies.

  1. Annealing dependence of magnetic properties in nanostructured Sm0.5Y0.5Co5

    International Nuclear Information System (INIS)

    Elizalde-Galindo, J.T.; Hidalgo, J.L.; Botez, C.E.; Matutes-Aquino, J.A.

    2008-01-01

    Nanocrystalline Sm 0.5 Y 0.5 Co 5 powders with high coercivity H C and enhanced remanence M r were prepared by mechanical milling and subsequent annealing. Annealing temperatures T ranging from 973 to 1173 K, and times t ranging from 1 to 5 min were used. X-ray diffraction (XRD) and DC-magnetization measurements were carried out to study the microstructure and magnetic properties of these samples. XRD patterns demonstrate that the average grain size of the nanocrystalline powders depends on the annealing temperature T and time t: ranges from 11 nm (for T=973 K and t=1 min) to 93 nm (for T=1173 K and t=5 min). Magnetic measurements performed at room temperature indicate high coercivity values (H C >955 kA/m), and enhanced remanence (M r /M max >0.5) for all samples. A strong annealing-induced grain size dependence of these magnetic properties was found

  2. Magnetic and conductivity study on Mn0.5Ru0.5Co2O4 spinel

    International Nuclear Information System (INIS)

    Bhowmik, R.N.; Ranganathan, R.

    2003-01-01

    The magnetic measurements suggest that Mn 0.5 Ru 0.5 Co 2 O 4 is a ferrimagnet with T c ≅ 140 K followed by irreversibility between zero field cooled and field cooled magnetization and peak in zero field cooled maximum at T m ≅ 100 K on decreasing the temperature. The scaling analysis of the conductivity (G) as a function of frequency (f) with functional form G p (f)/G o ∼ (f/f c ) n suggests two activated regimes at above and below of 210 K, respectively. The G o vs T shows semi-conducting behaviour of the sample. (author)

  3. Properties of La0.5Sr0.5CoO3 thin films grown by laser ablation

    International Nuclear Information System (INIS)

    Drozdov, Yu.N.; Klyuenkov, E.B.; Salashenko, N.N.; Suslov, L.A.

    1997-01-01

    The epitaxial films of lanthanum-strontium cobaltate La 0.5 Sr 0.5 CoO 3 (LSCO) are obtained on the neodium gallate and strontium titanate substrates. It is established that the LSCO layer lattice has tetragonal distortion, the degree where of depends on the oxygen deficit. The LSCO specific resistance at room temperature is approximately equal to 200 μOhm cm. The resistance dependence on temperature is of metal character. The possibility is shown of utilizing the LSCO as electrode material by fabrication of condenser structures on the basis of DbZr 1-x Ti x O 3 ferroelectric films

  4. Tetrakis(acetonitrilecopper(I hydrogen oxalate–oxalic acid–acetonitrile (1/0.5/0.5

    Directory of Open Access Journals (Sweden)

    A. Timothy Royappa

    2013-10-01

    Full Text Available In the title compound, [Cu(CH3CN4](C2HO4·0.5C2H2O4·0.5CH3CN, the CuI ion is coordinated by the N atoms of four acetonitrile ligands in a slightly distorted tetrahedral environment. The oxalic acid molecule lies across an inversion center. The acetonitrile solvent molecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid molecules are linked via O—H...O hydrogen bonds, forming chains along [010].

  5. Polar and semipolar GaN/Al0.5Ga0.5N nanostructures for UV light emitters

    Science.gov (United States)

    Brault, J.; Rosales, D.; Damilano, B.; Leroux, M.; Courville, A.; Korytov, M.; Chenot, S.; Vennéguès, P.; Vinter, B.; De Mierry, P.; Kahouli, A.; Massies, J.; Bretagnon, T.; Gil, B.

    2014-06-01

    AlxGa1-xN-based ultra-violet (UV) light emitting diodes (LEDs) are seen as the best solution for the replacement of traditional mercury lamp technology. By adjusting the Al concentration, a large emission spectrum range from 360 nm (GaN) down to 200 nm (AlN) can be covered. Owing to the large density of defects typically present in AlxGa1-xN materials usually grown on sapphire substrates, LED efficiencies still need to be improved. Taking advantage of the 3D carrier confinement, quantum dots (QDs) are among the solutions currently under investigation to improve the performances of UV LEDs. The objectives of this work are to present and discuss the morphological and optical properties of GaN nanostructures grown by molecular beam epitaxy on the (0 0 0 1) and the (11-22) orientations of Al0.5Ga0.5N. In particular, the dependence of the morphological properties of the nanostructures on the growth conditions and the surface orientation will be presented. The optical characteristics as a function of the nanostructure design (size, shape and dimensionality) will also be shown and discussed. The electroluminescence characteristics of a first series of QD-based GaN/Al0.5Ga0.5N LEDs grown on the polar (0 0 0 1) plane will be investigated.

  6. Polar and semipolar GaN/Al0.5Ga0.5N nanostructures for UV light emitters

    International Nuclear Information System (INIS)

    Brault, J; Damilano, B; Leroux, M; Courville, A; Korytov, M; Chenot, S; Vennéguès, P; Vinter, B; De Mierry, P; Kahouli, A; Massies, J; Rosales, D; Bretagnon, T; Gil, B

    2014-01-01

    Al x Ga 1−x N-based ultra-violet (UV) light emitting diodes (LEDs) are seen as the best solution for the replacement of traditional mercury lamp technology. By adjusting the Al concentration, a large emission spectrum range from 360 nm (GaN) down to 200 nm (AlN) can be covered. Owing to the large density of defects typically present in Al x Ga 1−x N materials usually grown on sapphire substrates, LED efficiencies still need to be improved. Taking advantage of the 3D carrier confinement, quantum dots (QDs) are among the solutions currently under investigation to improve the performances of UV LEDs. The objectives of this work are to present and discuss the morphological and optical properties of GaN nanostructures grown by molecular beam epitaxy on the (0 0 0 1) and the (11–22) orientations of Al 0.5 Ga 0.5 N. In particular, the dependence of the morphological properties of the nanostructures on the growth conditions and the surface orientation will be presented. The optical characteristics as a function of the nanostructure design (size, shape and dimensionality) will also be shown and discussed. The electroluminescence characteristics of a first series of QD-based GaN/Al 0.5 Ga 0.5 N LEDs grown on the polar (0 0 0 1) plane will be investigated. (invited article)

  7. Hydrothermal synthesis of a photovoltaic material based on CuIn0.5Ga0.5Se2

    Science.gov (United States)

    Castellanos Báez, Y. T.; Fuquen Peña, D. A.; Gómez-Cuaspud, J. A.; Vera-López, E.; Pineda-Triana, Y.

    2017-12-01

    The present work report, the synthesis and characterization of the CuIn0.5Ga0.5Se2 system (abbreviated CIGS), by the implementation of a hydrothermal route, in order to obtain a solid with appropriate properties in terms of surface, morphological and texture properties for potential applications in the design of photovoltaic cells. The synthesis was carried out using the corresponding stoichiometric quantities (Cu:In:Ga:Se 1:0.5:0.5:2), which were mixed in a Teflon vessel under stirring conditions. The homogeneous solution was treated in a steel autoclave at 300°C for 72 hours at the end of which the resulting material was characterized by X-Ray Diffraction (XRD) and Rietveld refinement. The results of the structural characterization allowed to confirm the obtaining of a chalcopyrite type structure, with a I-42 d (122) structure and cell parameters a=0.570, b=0.570, c=1.140nm, α=90, β=90, γ=90° oriented along (1 0 4) facet, detecting the presence of a secondary phases, related with CuInSe and CuIn metallic selenides, derived from synthesis process. The structural refinement allowing to validate the obtaining of a nanometric crystalline material (10-20nm) for potential applications in field of photovoltaic technology.

  8. Analysis of glow curve of GaS{sub 0.5}Se{sub 0.5} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Mehmet, E-mail: mehmet.isik@atilim.edu.tr [Department of Electrical and Electronics Engineering, Atilim University, 06836 Ankara (Turkey); Delice, Serdar [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Gasanly, Nizami [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Virtual International Scientific Research Centre, Baku State University, 1148 Baku (Azerbaijan)

    2015-12-15

    Characterization of shallow trapping centers in GaS{sub 0.5}Se{sub 0.5} crystals grown by a Bridgman method was carried out in the present work using thermoluminescence (TL) measurements performed in the low temperature range of 10–300 K. The activation energies of the trapping centers were obtained under the light of results of various analysis methods. The presence of three trapping centers located at 6, 30 and 72 meV was revealed. The analysis of the experimental glow curve gave reasonable results under the model that assumes slow retrapping which states the order of kinetics as b=1. Heating rate dependence of the observed TL peaks was studied for the rates between 0.4 and 1.0 K/s. Distribution of the traps was also investigated using an experimental technique based on the thermal cleaning of centers giving emission at lower temperatures. The distributed levels with activation energies increasing from 6 to 136 meV were revealed by increasing the stopping temperature from 10 to 52 K. - Highlights: • TL measurements were performed in the 10–300 K range on GaS{sub 0.5}Se{sub 0.5} crystals. • Atomic composition ratio of the elements was found. • Three trapping centers located at 6, 30 and 72 meV were revealed. • Distribution of trapping centers was studied on as-grown crystal.

  9. High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

    Science.gov (United States)

    Liu, Zhen; Ren, Weijun; Peng, Ping; Guo, Shaobo; Lu, Teng; Liu, Yun; Dong, Xianlin; Wang, Genshui

    2018-04-01

    Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ˜ 3.7 × 10-8 C cm-2 K-1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10-10 m/V, 2.89 × 10-2 m2/C, and 1.15 × 10-5 Pa-1/2 at 1 kHz and 1.32 × 10-10 m/V, 2.70 × 10-2 m2/C, and 1.09 × 10-5 Pa-1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ˜400 × 10-8 C cm-2 K-1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

  10. SHAKER Version 0.0/5 Pre-release Notes

    CERN Document Server

    CERN. Geneva

    1993-01-01

    SHAKER V0.0/5 is a pre-release of a simple cocktail central rapidity phase space event generator developed for the simulation of LHC Heavy Ion events. A modified version of JETSET 7.3 (the / LUJETS / common has been enlarged to 50000 particles and the LUEDIT routine has been modified to rearrange the particle weights vectors when called with MEDIT=1) is used to manage the events. All event information is included in / LUJETS / according to Lund conventions [1].

  11. Polymorphic phase transition dependence of piezoelectric properties in (K0.5Na0.5)NbO3-(Bi0.5K0.5)TiO3 lead-free ceramics

    International Nuclear Information System (INIS)

    Du Hongliang; Zhou Wancheng; Luo Fa; Zhu Dongmei; Qu Shaobo; Li Ye; Pei Zhibin

    2008-01-01

    Lead-free ceramics (1 - x)(K 0.5 Na 0.5 )NbO 3 -x(Bi 0.5 K 0.5 )TiO 3 [(1 - x)KNN-xBKT] were synthesized by conventional solid-state sintering. The phase structure, microstructure and electrical properties of (1 - x)KNN-xBKT ceramics were investigated. At room temperature, the polymorphic phase transition (from the orthorhombic to the tetragonal phase) (PPT) was identified at x = 0.02 by the analysis of x-ray diffraction patterns and dielectric spectroscopy. Enhanced electrical properties (d 33 = 251 pC N -1 , k p = 0.49, k t = 0.50, ε 33 T / ε 0 =1260, tan δ = 0.03 and T C = 376 deg. C) were obtained in the ceramics with x = 0.02 owing to the formation of the PPT at 70 deg. C and the selection of an optimum poling temperature. The related mechanisms for high piezoelectric properties in (1 - x)KNN-xBKT (x = 0.02) ceramics were discussed. In addition, the results confirmed that the selection of the optimum poling temperature was an effective way to further improve the piezoelectric properties of KNN-based ceramics. The enhanced properties were comparable to those of hard Pb(Zr, Ti)O 3 ceramics and indicated that the (1 - x)KNN-xBKT (x = 0.02) ceramic was a promising lead-free piezoelectric candidate material for actuator and transducer applications

  12. [Oral hygiene customs in 6-12 year old schoolchildren].

    Science.gov (United States)

    Hernández-Martínez, César Tadeo; Medina-Solís, Carlo Eduardo; Robles-Bermeo, Norma Leticia; Mendoza-Rodríguez, Martha; Veras-Hernández, Miriam; De la Rosa-Santillana, Rubén; Escoffié-Ramírez, Mauricio; Márquez-Rodríguez, Sonia

    2014-01-01

    OBJECTIVE. To characterize utilization of oral hygiene devices and customs in schoolchildren. MATERIAL AND METHODS. We performed a cross-sectional study in 1,404 schoolchildren (6- 12 year olds) from 14 public schools in Pachuca, Hidalgo, México, using a questionnaire for sociodemographic variables and 1) Tooth brushing frequency (customs were 85.5% tooth brushing, 90.9% toothpaste, 19.4% flossing, and 28.2% mouthwash. Only 11.8% of participants reported utilization in all 4 categories. We observed differences (p < 0.05) across sexes only in the use of toothpaste, as women used it more often. Differences across age were observed (p < 0.05) for tooth brushing (younger children brushed more often) and flossing (older children flossed more often). CONCLUSIONS. Tooth brushing was the oral hygiene practice more often performed in this sample, with other frequencies being relatively low. There were differences by age and sex across some variables.

  13. Permittivity and modulus spectroscopic study of BaFe0.5Nb0.5O3 ceramics

    Directory of Open Access Journals (Sweden)

    Subrat K. Kar

    2013-12-01

    Full Text Available Ba(Fe0.5Nb0.5O3 (BFN powder was synthesized in single perovskite phase by conventional solid state reaction route and BFN ceramic was obtained by uniaxial pressing and sintering at 1350 °C. Complex immittance like: permittivity and modulus spectroscopic formalism were simultaneously used to explain dielectric behaviour of the ceramics. The activation energy calculated from dielectric relaxation below 100 °C was found to be ~0.19 eV. The activation energy obtained from modulus spectra above 100 °C was ~0.59 eV. The space charge polarization model was used to explain the origin of relaxation and “giant” permittivity of BFN ceramics near room temperature.

  14. Oscillatory exchange bias and training effects in nanocrystalline Pr0.5Ca0.5MnO3

    Directory of Open Access Journals (Sweden)

    S. Narayana Jammalamadaka

    2012-03-01

    Full Text Available We report on exchange bias effects in 10 nm particles of Pr0.5Ca0.5MnO3 which appear as a result of competing interactions between the ferromagnetic (FM/anti-ferromagnetic (AFM phases. The fascinating new observation is the demonstration of the temperature dependence of oscillatory exchange bias (OEB and is tunable as a function of cooling field strength below the SG phase, may be attributable to the presence of charge/spin density wave (CDW/SDW in the AFM core of PCMO10. The pronounced training effect is noticed at 5 K from the variation of the EB field as a function of number of field cycles (n upon the field cooling (FC process. For n > 1, power-law behavior describes the experimental data well; however, the breakdown of spin configuration model is noticed at n ≥ 1.

  15. Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2

    KAUST Repository

    Nazir, Safdar

    2011-01-31

    Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Unraveling the magnetic properties of BiFe0.5Cr0.5O3 thin films

    Directory of Open Access Journals (Sweden)

    G. Vinai

    2015-11-01

    Full Text Available We investigate the structural, chemical, and magnetic properties on BiFe0.5Cr0.5O3 (BFCO thin films grown on (001 (110 and (111 oriented SrTiO3 (STO substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

  17. Phase transitions in Fe{sub 0.5}Co{sub 0.5} (110) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Dámaso, G., E-mail: gramirezd@ipn.mx [Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del Instituto Politécnico Nacional, Av. Ticomán No. 600, Col. San José Ticomán, Del. G. A. M., C. P. 07330 Ciudad de México (Mexico); Castillo-Alvarado, F.L. [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9, Col. San Pedro Zacatenco, C. P. 07738 Ciudad de México (Mexico); Rojas-Hernández, E. [Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del Instituto Politécnico Nacional, Av. Ticomán No. 600, Col. San José Ticomán, Del. G. A. M., C. P. 07330 Ciudad de México (Mexico)

    2016-12-15

    In this paper, we present calculations for two second-order phase transitions in (110) Fe{sub 0.5}Co{sub 0.5} thin films with 11, 15, and 19 monoatomic layers. The lattice and magnetic transitions are based on thermodynamic equilibrium considerations of the magnetic alloy. The procedure proposed by Valenta and Sukiennicki was applied to calculate the composition x(i), the lattice order parameter t(i), and the magnetic order parameter σ(i) as a function of temperature T. We confirmed that both phase transitions, lattice and magnetic, are of the second order, in accordance with experimental results in the literature. The obtained behavior of these parameters indicates their inhomogeneity due to the boundary conditions on the surfaces of the thin film.

  18. Strain profile and polarization enhancement in Ba0.5Sr0.5TiO3 thin films

    International Nuclear Information System (INIS)

    Amir, F.Z.; Donner, W.; Aspelmeyer, M.; Noheda, B.; Xi, X.X.; Moss, S.C.

    2012-01-01

    The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba 0.5 Sr 0.5 TiO 3 (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Magnetoresistive memory in phase-separated La0.5Ca0.5MnO3

    Energy Technology Data Exchange (ETDEWEB)

    Sacanell, J. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina)]. E-mail: sacanell@cnea.gov.ar; Parisi, F. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Levy, P. [Departamento de Fisica, Unidad de Actividad Fisica-Centro Atomico de Constituyentes, CNEA, Av. Gral. Paz 1499, San Martin 1650, Pcia. de Buenos Aires (Argentina); Ghivelder, L. [Instituto de Fisica, UFRJ, Rio de Janeiro (Brazil)

    2004-12-31

    We have studied a non-volatile memory effect in the mixed valent compound La0.5Ca0.5MnO3 induced by magnetic field (H). In a previous work (Phys. Rev. B 65 (2002) 104403), it has been shown that the response of this system upon application of H strongly depends on the temperature range, related to three well-differentiated regimes of phase separation occurring below 220K. In this work we compare memory capabilities of the compound, determined following two different experimental procedures for applying H, namely zero-field cooling and field cooling the sample. These results are analyzed and discussed within the scenario of phase separation.

  20. Magnetoresistive memory in phase-separated La0.5Ca0.5MnO3

    International Nuclear Information System (INIS)

    Sacanell, J.; Parisi, F.; Levy, P.; Ghivelder, L.

    2004-01-01

    We have studied a non-volatile memory effect in the mixed valent compound La0.5Ca0.5MnO3 induced by magnetic field (H). In a previous work (Phys. Rev. B 65 (2002) 104403), it has been shown that the response of this system upon application of H strongly depends on the temperature range, related to three well-differentiated regimes of phase separation occurring below 220K. In this work we compare memory capabilities of the compound, determined following two different experimental procedures for applying H, namely zero-field cooling and field cooling the sample. These results are analyzed and discussed within the scenario of phase separation

  1. Polar phase transitions in heteroepitaxial stabilized La0.5Y0.5AlO3 thin films

    Science.gov (United States)

    Liu, Shenghua; Zhang, Chunfeng; Zhu, Mengya; He, Qian; Chakhalian, Jak; Liu, Xiaoran; Borisevich, Albina; Wang, Xiaoyong; Xiao, Min

    2017-10-01

    We report on the fabrication of epitaxial La0.5Y0.5AlO3 ultrathin films on (001) LaAlO3 substrates. Structural characterizations by scanning transmission electron microscopy and x-ray diffraction confirm the high quality of the film with a - b + c - AlO6 octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO3 and YAlO3, second harmonic generation measurements on the thin films suggest a nonpolar-polar phase transition at T c near 500 K, and a polar-polar phase transition at T a near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc2 1 and Pmn2 1 space group, while the high temperature nonpolar structure belongs to the Pbnm space group.

  2. Synthesis of nanocrystalline Zn0.5Mn0.5Fe2O4 via in situ polymerization technique

    International Nuclear Information System (INIS)

    Liu Xianming; Fu Shaoyun

    2007-01-01

    Nanocrystalline Zn 0.5 Mn 0.5 Fe 2 O 4 was synthesized through the pyrolysis of polyacrylate salt precursors prepared via in situ polymerization of the metal salts and acrylic acid. The pyrolysis behavior of the polymeric precursors was studied by use of thermal analysis. The as-obtained product was characterized by powder X-ray diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED) pattern, scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) analysis. The results revealed that the particle size is in the range of 15-25 nm for Zn-Mn ferrites with good crystallinity. Magnetic properties of the sample at 300 K were measured using a vibrating sample magnetometer, which showed that the sample exhibited characteristics of superparamagnetism

  3. Sinterability studies on K0.5Na0.5NbO3 using laser as energy source

    International Nuclear Information System (INIS)

    Tian Xiaoyong; Dittmar, Anne; Melcher, Joerg; Heinrich, Juergen G.

    2010-01-01

    The sinterability of K 0.5 Na 0.5 NbO 3 (KNN) ceramics by a laser beam has been investigated in the present research. A 100 W CO 2 laser with a beam diameter of 0.6 mm has been used to sinter the KNN specimens prepared on a uniaxial pressing machine. The relations between laser power and thickness of densified layer, crystallographic structures and phase compositions have been studied. A comparison has been made between laser and furnace sintered KNN samples according to the SEM, XRD and XRF results. The possibility of KNN used for the layer-wise laser direct sintering 3D components has been confirmed in this paper.

  4. Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2

    KAUST Repository

    Nazir, Safdar; Zhu, Zhiyong; Schwingenschlö gl, Udo

    2011-01-01

    Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Strain induced magnetism in La0.5Ca0.5MnO3 systems

    Energy Technology Data Exchange (ETDEWEB)

    Tietze, Thomas; Nolle, Daniela; Schuetz, Gisela; Goering, Eberhard [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany); Aydogdu, Guelguen; Habermeier, Hanns-Ulrich [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2009-07-01

    The La{sub 1-x}Ca{sub x}MnO{sub 3} exhibits, besides the double exchange relate magneto resistive effects, many interesting properties as a function of the doping level. Depending on the doping level x the system may exhibit ferromagnetism, antiferromagnetism, orbital ordering, and charge ordering. Epitaxial tensile and compressive strains are very important for the fine tuning of the lattice degree of freedom and therefore for the magnetic nearest neighbor coupling. By *adjusting* tensile and compressive strain with corresponding substrates one can switch between FM and AFM coupling between the FM ordered ab-planes. In order to investigate the influence of different substrates and relaxation effects element specific XMCD measurements were performed on La{sub 0.5}Ca{sub 0.5}MnO{sub 3} systems.

  6. Colossal elastoresistance, electroresistance and magnetoresistance in Pr0.5Sr0.5MnO3 thin films

    International Nuclear Information System (INIS)

    Chen, Liping; Guo, Xuexiang; Gao, J.

    2016-01-01

    Pr 0.5 Sr 0.5 MnO 3 thin films on substrates of (001)-oriented LaAlO 3 were epitaxially grown by pulsed laser deposition. It was found that a substrate-induced strain of ~1.3% brings a great resistivity change of ~98% at 25 K. We studied the dependence of resistivity on the applied electric current and magnetic field. In the greatly strained films of 60 nm thickness the electroresistance ER=[ρ(I 1 μA )−ρ(I 1000 μA )]/ρ(I 1 μA ) reaches ~70% at T=25 K, much higher than ER~7% in the strain-relaxed films of 400 nm thickness, implying the strain effect on ER. Also the magnetoresistance of the film falls with strain-relaxation. Therefore the electric properties of the film could be efficiently modified by strain, electric current and magnetic field. All of them may be explained by the effect on the percolative phase separation and competition in the half-doped manganite material. The manganite films located at phase boundary are expected to be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance due to the multiphase coexistence. - Highlights: • The electric current-induced electroresistance (ER) and magnetoresistance (MR)studies on PLD grown Pr 0.5 Sr 0.5 MnO 3 /(001) LaAlO 3 films were found to be greatly sensitive to the film thickness arising from the strain. • It is shown that, 60 nm film exhibit compressive in-plane strain which leads to phase separation and hence colossal MR and ER. • Our results suggest that the manganites located at phase boundary may be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance.

  7. The cross-plane thermoelectric properties of p-Ge/Si0.5Ge0.5 superlattices

    International Nuclear Information System (INIS)

    Ferre Llin, L.; Samarelli, A.; Weaver, J. M. R.; Dobson, P. S.; Paul, D. J.; Cecchi, S.; Chrastina, D.; Isella, G.; Etzelstorfer, T.; Stangl, J.; Müller Gubler, E.

    2013-01-01

    The electrical conductivity, Seebeck coefficients, and thermal conductivities of a range of p-type Ge/Si 0.5 Ge 0.5 superlattices designed for thermoelectric generation and grown by low energy plasma enhanced chemical vapor deposition have been measured using a range of microfabricated test structures. For samples with barriers around 0.5 nm in thickness, the measured Seebeck coefficients were comparable to bulk p-SiGe at similar doping levels suggesting the holes see the material as a random bulk alloy rather than a superlattice. The Seebeck coefficients for Ge quantum wells of 2.85 ± 0.85 nm increased up to 533 ± 25 μV/K as the doping was reduced. The thermal conductivities are between 4.5 to 6.0 Wm −1 K −1 which are lower than comparably doped bulk Si 0.3 Ge 0.7 but higher than undoped Si/Ge superlattices. The highest measured figure of merit ZT was 0.080 ± 0.011 obtained for the widest quantum well studied. Analysis suggests that interface roughness is presently limiting the performance and a reduction in the strain between the quantum wells and barriers has the potential to improve the thermoelectric performance

  8. High resolution imaging of La0.5Ba0.5MnO-LaMnO superlattice

    International Nuclear Information System (INIS)

    Shapoval, O.; Belenchuk, A.; Verbeeck, J.; Moshnyaga, V.

    2013-01-01

    Full text: Artificial low dimensional systems of tailored on atomic layer level manganites is a very promising class of materials for future spintronic applications. The high resolution transmission electron microscopy imaging provides a powerful approach to extract structural, chemical and functional information on atomic level in a real space. Recently, we have reported on the Metalorganic Aerosol Deposition synthesis and properties of superlattices (SL) composed from (LaMnO 3 ) n and (La 0.5 Ba 0.5 MnO 3 ) 2n with n=1-2 of perovskite monolayers. The functional properties of digitally synthesized SL are similar to the optimal doped 'bulk' thin film material. The similarities between their properties can be interpreted in frame of the many-body interactions responsible for the properties of the single-layer and bilayer manganites. This work presents the systematic studies of atomically resolved structure of (LaMnO 3 ) n /(La 0.5 Ba 0.5 MnO 3 ) 2n , n=1 by high angle annular dark field scanning transmission electron microscopy (HAADF STEM) and electron energy loss spectroscopy (EELS). The combination of atomic-resolution Z-contrast and EELS represents a powerful method to link the atomic and electronic structure of solids with macroscopic properties. All images were obtained along orientations and low magnification one shows an overview of a whole 40-nm thick structure, whereas magnified high-resolution images demonstrate an epitaxial growth of LBMO/LMO superlattice on SrTiO 3 substrate. The SL-substrate interface is coherent and free of defects, but reveals a high level of La diffusion into SrTiO 3 . EELS together with STEM are used for probing of a local chemical composition as well as a local electronic state of transition metals and oxygen. Small modulations in the La and Ba EELS signals, which are corresponded to the LBMO and LMO layers, can be observed. The observed features at the substrate interface as well as the SL periodicity in EELS profiles are

  9. Birefringence imaging of phase transitions: application to Na0.5Bi0.5TiO3

    International Nuclear Information System (INIS)

    Geday, M.; Kreisel, J.; Glazer, A.M.; Roleder, K.

    2000-01-01

    In recent years a number of imaging techniques to determine the optical properties of materials, either in reflection or in transmission, have been developed. Here the use of an imaging version of the so-called rotating-polarizer method in the study of phase transformations in crystals is demonstrated. This method creates false-coloured images representing the light transmission I 0 , the extinction angle φ (orientation of the optical indicatrix) and vertical stroke sin δ vertical stroke, a function of the retardation resulting from the birefringence (and a measure of the magnitude of optical anisotropy). When combined with a computer-controlled heating stage, this method provides an opportunity to create separate moving images of orientation and magnitude of optical anisotropy, showing the dynamics of twinning and domain-wall behaviour during temperature changes. It is believed that this is the first time that quantitative imaging of changes in birefringence has been used in this way to describe phase transitions. Two-phase transitions in a crystal of Na 0.5 Bi 0.5 TiO 3 (NBT) are presented as examples of the use of the system. (orig.)

  10. Field induced ferromagnetic fraction enlargement in phase separated La_0.5Ca_0.5MnO_3

    Science.gov (United States)

    Ghivelder, Luis; Freitas, R. S.; Sacanel, J.; Parisi, F.; Levy, P.

    2001-03-01

    A systematic study of the magnetic and transport properties of a series of phase separated La_0.5Ca_0.5MnO3 compounds is reported. The investigated samples all have the same composition but different grain sizes, which modifies the volume fraction of the coexisting ferromagnetic (FM) and antiferromagnetic charge-ordered (AFM-CO) phases. Magnetoresistance and magnetization measurements were performed with two different experimental procedures: a standard field-cooled cooling (FC) mode, and a second method in which the field is turned on only while measuring each data point, and switched off while cooling the samples. Magnetization and magnetoresistance measurements display big differences when comparing the data obtained with the different procedures. The overall results are interpret in terms of a field induced FM fraction enlargement. In transport measurements this effect yield a percolative transition. Magnetization data shows evidence for the formation of AFM-CO regions within the FM phase. * e-mail: luisghiv@if.ufrj.br

  11. Exchange bias induced at a Co2FeAl0.5Si0.5/Cr interface

    International Nuclear Information System (INIS)

    Yu, C N T; Vick, A J; Inami, N; Ono, K; Frost, W; Hirohata, A

    2017-01-01

    In order to engineer the strength of an exchange bias in a cubic Heusler alloy layer, crystalline strain has been induced at a ferromagnet/antiferromagnet interface by their lattice mismatch in addition to the conventional interfacial exchange coupling between them. Such interfaces have been formed in (Co 2 FeAl 0.5 Si 0.5 (CFAS)/Cr) 3 structures grown by ultrahigh vacuum molecular beam epitaxy. The magnetic and structural properties have been characterised to investigate the exchange interactions at the CFAS/Cr interfaces. Due to the interfacial lattice mismatch of 1.4%, the maximum offset of 18 Oe in a magnetisation curve has been measured for the case of a CFAS (2 nm)/Cr (0.9 nm) interface at 193 K. The half-metallic property of CFAS has been observed to remain unchanged, which agrees with the theoretical prediction by Culbert et al (2008 J. Appl. Phys . 103 07D707). Such a strain-induced exchange bias may provide insight of the interfacial interactions and may offer a wide flexibility in spintronic device design. (paper)

  12. Cellulose-precursor synthesis of nanocrystalline Co0.5Cu0.5Fe2O4 spinel ferrites

    International Nuclear Information System (INIS)

    Ounnunkad, Kontad; Phanichphant, Sukon

    2012-01-01

    Highlights: ► Synthesis of spinel copper cobalt nanoferrite particles from a cellulose precursor for the first time. Control of nanosize and properties of nanoferrites can take place by varying the calcining temperature. The simple, low cost, easy cellulose process is a choice of nanoparticle processing technology. -- Abstract: Nanocrystalline Cu 0.5 Co 0.5 Fe 2 O 4 powders were prepared via a metal-cellulose precursor synthetic route. Cellulose was used as a fuel and a dispersing agent. The resulting precursors were calcined in the temperature range of 450–600 °C. The phase development of the samples was determined by using Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD). The field-dependent magnetizations of the nanopowders were measured by vibrating sample magnetometer (VSM). All XRD patterns are of a spinel ferrite with cubic symmetry. Microstructure of the ferrites showed irregular shapes and uniform particles with agglomeration. From XRD data, the crystallite sizes are in range of 16–42 nm. Saturation magnetization and coercivity increased with increasing calcining temperature due to enhancement of crystallinity and reduction of oxygen vacancies.

  13. Colossal elastoresistance, electroresistance and magnetoresistance in Pr0.5Sr0.5MnO3 thin films

    Science.gov (United States)

    Chen, Liping; Guo, Xuexiang; Gao, J.

    2016-05-01

    Pr0.5Sr0.5MnO3 thin films on substrates of (001)-oriented LaAlO3 were epitaxially grown by pulsed laser deposition. It was found that a substrate-induced strain of 1.3% brings a great resistivity change of 98% at 25 K. We studied the dependence of resistivity on the applied electric current and magnetic field. In the greatly strained films of 60 nm thickness the electroresistance ER=[ρ(I1 μA)-ρ(I1000 μA)]/ρ(I1 μA) reaches 70% at T=25 K, much higher than ER 7% in the strain-relaxed films of 400 nm thickness, implying the strain effect on ER. Also the magnetoresistance of the film falls with strain-relaxation. Therefore the electric properties of the film could be efficiently modified by strain, electric current and magnetic field. All of them may be explained by the effect on the percolative phase separation and competition in the half-doped manganite material. The manganite films located at phase boundary are expected to be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance due to the multiphase coexistence.

  14. Phase competition by design in R0.5Ba0.5MnO3

    Science.gov (United States)

    Nowadnick, Elizabeth; He, Jiangang; Fennie, Craig

    Phase competition between distinct ground states can arise from interactions on similar energy scales between the spin, charge, lattice, and orbital degrees of freedom. This competition can result in large responses to external perturbations. For example, the colossal magnetoresistance effect in the rare-earth manganites R1-xAxMnO3 arises out of competing ferromagnetic metallic and charge/orbital-ordered antiferromagnetic insulating states. Phase competition between polar and magnetic ground states is a promising strategy to realize polarization (magnetization) control with a magnetic (electric) field, which is major goal in multiferroics research. In this regard, the half-doped A-site ordered manganite Sm0.5Ba0.5MnO3 is of particular interest, because the charge/orbital-ordered antiferromagnetic insulating state in this material is polar. We use a combination of group theoretic methods and first-principles calculations to elucidate the origin of this polar state, and show that epitaxial strain can tune the material to a regime where there is a strong competition between the polar insulating state and the ferromagnetic metallic state. We then explore how to achieve electric and magnetic field control of the order parameters in this system.

  15. Simple hydrothermal synthesis and sintering of Na0.5Bi0.5TiO3 nanowires

    International Nuclear Information System (INIS)

    Jiang Xiangping; Lin Mei; Tu Na; Chen Chao; Zhou Shulan; Zhan Hongquan

    2011-01-01

    Highlights: → Single-crystalline NBT nanowires were synthesized using a simple hydrothermal route. → Reaction time can significantly influence the growth behavior of powders. → 1D growth mechanism of NBT corresponds to the dissolution-recrystallization mechanism. → NBT ceramics derived from nanowires showed typical characteristics of relax or ferroelectrics. - Abstract: Single-crystalline Na 0.5 Bi 0.5 TiO 3 (NBT) nanowires, with diameters of 100 nm and lengths of about 4 μm, were synthesized by using a simple hydrothermal method. Phase composition, morphology and microstructure of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effects of reaction temperature and reaction time on precipitation of the NBT nanowires were investigated. It was found that reaction time significantly influenced the growth behavior of the powders in the hydrothermal system. Based on the experimental results, the one-dimensional (1D) growth mechanism of the NBT was governed by a dissolution-recrystallization mechanism. NBT ceramics derived from the nanowires showed typical characteristics of relaxor ferroelectrics, with diffuseness exponent γ of as high as 1.73.

  16. Novel specific heat and magnetoresistance behavior of Tb0.5Ho0.5Mn2Si2

    Science.gov (United States)

    Pandey, Swati; Siruguri, V.; Rawat, R.

    2018-04-01

    In this report, we study temperature dependent heat capacity and electrical resistance of Tb1-xHoxMn2Si2 (x = 0.5). Two successive low temperature magnetic transitions T1 (˜15 K) and T2 (˜25 K) are observed from both measurements. Anomalous rise in heat capacity at low temperatures is ascribed to the nuclear Schottky effect. Sommerfeld coefficient (γ), Debye temperature (θD) and density of states at Fermi level N(EF) is calculated from the zero field specific heat data. We observe 4f contribution to heat capacity from T1 to 100K, which is attributed to crystal field effect. In the electrical transport study, application of the magnetic field shows a substantial change around the ordering temperature of rare earth moment resulting in large positive magnetoresistance of about 20% with field change of 6T.

  17. Charge dynamics of 57Fe probe atoms in La2Li0.5Cu0.5O4

    Science.gov (United States)

    Presniakov, I. A.; Sobolev, A. V.; Rusakov, V. S.; Moskvin, A. S.; Baranov, A. V.

    2018-06-01

    The objective of this study is to characterize the electronic state and local surrounding of 57Fe Mössbauer probe atoms within iron-doped layered perovskite La2Li0.5Cu0.5O4 containing transition metal in unusual formal oxidation states "+3". An approach based on the qualitative energy diagrams analysis and the calculations within the cluster configuration interaction method have been developed. It was shown that a large amount of charge is transferred via Cu-O bonds from the O: 2p bands to the Cu: 3d orbitals and the ground state is dominated by the d9L configuration ("Cu2+-O-" state). The dominant d9L ground state for the (CuO6) sublattice induces in the environment of the 57Fe probe cations a charge transfer Fe3+ + O-(L) → Fe4+ + O2-, which transforms "Fe3+" into "Fe4+" state. The experimental spectra in the entire temperature range 77-300 K were described with the use of the stochastic two-level model based on the assumption of dynamic equilibrium between two Fe3+↔Fe4+ valence states related to the iron atom in the [Fe(1)O4]4- center. The relaxation frequencies and activation energies of the corresponding charge fluctuations were estimated based on Mössbauer data. The results are discussed assuming a temperature-induced change in the electronic state of the [CuO4]5- clusters in the layered perovskite.

  18. Towards sub-0.5 A electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Krivanek, O.L.; Nellist, P.D.; Dellby, N.; Murfitt, M.F.; Szilagyi, Z

    2003-09-15

    In the 4 years since the previous meeting in the SALSA series, aberration correction has progressed from a promising concept to a powerful research tool. We summarize the factors that have enabled 100-120 kV scanning transmission electron microscopes to achieve sub-A resolution, and to increase the current available in an atom-sized probe by a factor of 10 and more. Once C{sub s} is corrected, fifth-order spherical aberration (C{sub 5}) and chromatic aberration (C{sub c}) pose new limits on resolution. We describe a quadrupole/octupole corrector of a new design, which will correct all fifth-order aberrations while introducing less than 0.2 mm of additional C{sub c}. Coupled to an optimized STEM column, the new corrector promises to lead to routine sub-A electron probes at 100 kV, and to sub-0.5 A probes at higher operating voltages.

  19. A monolithic charge multiplexer with 0.5% accuracy

    International Nuclear Information System (INIS)

    Lewis, J.; McPherson, G.M.; Morrissey, M.C.; Thompson, J.C.; Tucker, A.W.

    1990-01-01

    This paper describes a 16 channel monolithic charge multiplexer providing a close tolerance, low cost, low power solution to the problem of handling the signals from detectors with large numbers of channels. Outputs may be wire-orred to increase the degree of multiplexing. A system designed with this chip and with suitable close tolerance processing downstream will have a gain match of ±0.5% and a front end chip cost of approximately $1 per channel. The chip is fabricated in CMOS technology and the test of a 1500 channel system has demonstrated the feasibility of CMOS in this context. The chip produces a prompt sum of the charges from the 16 signal sources and integrates and stores the individual charges for later serial readout. A single network provides amplifier bias and releases area to facilitate optimum noise performance and signal handling. Amplifier and bias network design together with p-well screens to isolate storage capacitors from the substrate provide the power line rejection essential in systems generating a trigger from large numbers of channels. (orig.)

  20. A-site driven ferroelectricity in K0.5Li0.5NbO3

    Science.gov (United States)

    Bilc, Daniel I.; Singh, D. J.

    2006-03-01

    Mixed A-site ferroelectric materials have gained recent attention. Here we report density functional calculations of KxLi1-xNbO3 perovskite supercells in order to understand the interplay between various lattice instabilities with size mismatch on the A-site and the role of the A and B site ions in this case. The calculations were done using the general potential LAPW method. For x=0.5, we find a ferroelectric ground state, even though the average tolerance factor is significantly smaller than unity and there is no stereochemically active A site ion. This is due to frustration due to the very different ionic radii of K and Li. We find very large off-centering of the Li ions, which distinguishes this compound. Relative to this the Nb off-centering is quite small. This is in contrast to most perovskite ferroelectrics where there is significant off-centering of all ions, and resulting cooperativity. Also because of the large Li off-centering it contributes strongly to the anisotropy between tetragonal and rhombohedral ground states, yielding a tetragonal ground state. Normally the anisotropy is determined by the interplay of B site off-centering and strain coupling. This work was supported by the Office of Naval Research and the Department of Energy.

  1. Nuclear research reactor 0.5 to 3 MW

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-05-15

    This nuclear reactor has been designed for radioisotope production, basic and applied research in reactor physics and nuclear engineering, neutron-beam experimentation, irradiation of various materials and training of scientific and technical personnel. It is located in the 'Production Area' of the Nuclear Technology Center. It is equipped with the necessary facilities for large-scale production of radioisotopes to be used in medicine as well as for other scientific and industrial purposes. In addition, it has a Neutronography Facility and the required equipment to perform Neutron-Activation Analysis. It is an open pool-type reactor, moderated and cooled with light water, fuelled with 20% enriched uranium. Its reflector are graphite and water. It has plate-type fuel elements clad in aluminium. The reactor core is located near the bottom of the demineralized water pool. It includes fuel elements, reflector and sample-holding devices for materials to be irradiated. This kind of configuration, which is widely used in research reactors, provides a high degree of safety since it prevents the core from becoming exposed under any circumstance and does not require any cooling system during reactor shutdown. Power output is between 0.5 to 3 MW{sub TH}, with a minimum thermal neutron flux of approx, 10{sup 13} n/cm{sup 2}{center_dot}sec, at irradiation zone almost with no modifications. Heat extraction is achieved by means of a cooling circuit which comprises two circulation pumps and a plate-type heat exchanger. Final heat dissipation to the atmosphere is performed through another cooling circuit which includes two circulation pumps and a cooling tower. Reactor control is accomplished with five neutron-absorbing rods positioned by means of especially designed elements and governed by the reactor's instrumentation and control system. Should an abnormal situation arise, gravity causes the rods to fall automatically, thus extinguishing the nuclear reaction. The reactor

  2. Nuclear research reactor 0.5 to 3 MW

    International Nuclear Information System (INIS)

    1992-05-01

    This nuclear reactor has been designed for radioisotope production, basic and applied research in reactor physics and nuclear engineering, neutron-beam experimentation, irradiation of various materials and training of scientific and technical personnel. It is located in the 'Production Area' of the Nuclear Technology Center. It is equipped with the necessary facilities for large-scale production of radioisotopes to be used in medicine as well as for other scientific and industrial purposes. In addition, it has a Neutronography Facility and the required equipment to perform Neutron-Activation Analysis. It is an open pool-type reactor, moderated and cooled with light water, fuelled with 20% enriched uranium. Its reflector are graphite and water. It has plate-type fuel elements clad in aluminium. The reactor core is located near the bottom of the demineralized water pool. It includes fuel elements, reflector and sample-holding devices for materials to be irradiated. This kind of configuration, which is widely used in research reactors, provides a high degree of safety since it prevents the core from becoming exposed under any circumstance and does not require any cooling system during reactor shutdown. Power output is between 0.5 to 3 MW TH , with a minimum thermal neutron flux of approx, 10 13 n/cm 2 ·sec, at irradiation zone almost with no modifications. Heat extraction is achieved by means of a cooling circuit which comprises two circulation pumps and a plate-type heat exchanger. Final heat dissipation to the atmosphere is performed through another cooling circuit which includes two circulation pumps and a cooling tower. Reactor control is accomplished with five neutron-absorbing rods positioned by means of especially designed elements and governed by the reactor's instrumentation and control system. Should an abnormal situation arise, gravity causes the rods to fall automatically, thus extinguishing the nuclear reaction. The reactor building has a ventilation

  3. Deformation-induced structural changes of amorphous Ni0.5Zr0.5 in molecular-dynamic simulations

    International Nuclear Information System (INIS)

    Brinkmann, K.

    2006-01-01

    The present work investigates the plastic deformation of metallic glasses by the aid of molecular-dynamic simulations. The parameters for the model system are adapted to those for a NiZr-alloy. In particular, the composition Ni 0.5 Zr 0.5 is used. The analyzed deformation simulations are conducted for small systems with 5184 atoms and large systems with 17500 atoms in a periodic simulation cell. The deformation simulations of pre-deformed samples are carried out either at constant shear-rate or at constant load, the latter mode modeling a creep experiment. Stress-strain curves for pre-deformed samples show a less pronounced stress-overshoot phenomenon. Creep-simulations of samples deformed beyond the yield region indicate a drastically reduced viscosity in these systems when compared to samples pre-deformed only up to the linear regime of the stress-strain curve. From analyzing the local atomic topology it is found that the transition from the highly viscous, hard-to-deform state of the undeformed or only weakly strained system into the easy-to-deform flow-state, present if the system is strained far beyond the yielding regime of the stress-strain curve, is connected with the formation of a region containing atoms with massive changes in their topology which is oriented along a diagonal plane of the simulation cell. The degree of localization of these deformation bands is influenced by temperature and shear-rate. In subsequent deformations of pre-deformed samples the regions with massive changes in the atomic topology are again susceptible to changes in the local atomic topology. By using methods from statistics, a significant difference in the distribution of atomic properties for the group of atoms with massive topology changes on the one hand and the group of atoms without changes in their topology on the other gets quantitatively ascertainable. From the differences in structural properties, e.g. potential energy, cage volumes, angular order parameters or atomic

  4. TRMM Microwave Imager (TMI) Level 3 Monthly 0.5 degree x 0.5 degree Profiling V7 (3A12) at GES DISC V7

    Data.gov (United States)

    National Aeronautics and Space Administration — This document provides basic information on 3A12, TMI Monthly 0.5 deg. x 0.5 deg. Profiling. Algorithm 3A12 produces global 0.5 deg. x 0.5 deg. monthly gridded means...

  5. [Suicide attempts of 48 children aged 6-12 years].

    Science.gov (United States)

    Berthod, C; Giraud, C; Gansel, Y; Fourneret, P; Desombre, H

    2013-12-01

    Research is limited on suicide attempts in children under 13 years of age. The objective of this study was to provide an in-depth description of this population. The present study is both retrospective and descriptive. Data were collected retrospectively from a file containing the causes for hospitalization of each child admitted into the Department of Child Psychiatry at the hôpital Femme-Mère-Enfant (hospices civils de Lyon). We included all patients under 13 years of age who were hospitalized for a suicide attempt between 2008 and 2011. The methods used to collect the medical records consisted in using a form made up of four major parts: suicide attempts, social environment, medical history, and therapy. The 26 girls and 22 boys included had a mean age of 11.52 years. The boys were younger than the girls (P=0.047) and their parents were usually separated (P=0.034). The boys used more violent means to commit suicide in comparison to the girls (P=0.048). On average, children using violent means were younger (P=0.013). Boys underwent more psychotherapy (P=0.027) and were prescribed more psychotropic medication in comparison to girls (P=0.051). Adjustment disorders (37.5%) and depression (27%) were the two main diagnoses for hospitalization. They were hospitalized on average (±standard deviation) 9.6 days (±10 days). Psychotherapy was organized when leaving the hospital (98%) with legal measures (8.3%), change of residence (12.5%), and prescription of psychotropic drugs (37.5%). None had physical complications. In children under 13 years of age, attempted suicide was more frequent in girls than boys. However, the sample included 18 girls and nine boys who were 12 years old (sex ratio of 12-year-olds, 0.5). There were more boys (16 boys/eight girls) in the children under 12 (sex ratio of 8- to 11-year-olds, 1.6). Children under 11 used more violent means (P=0.01). The literature also reports that more violent means lead to a greater risk of death by suicide

  6. Promoting Oral Health in 6-12 Year-Old Students: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Mehdi Hazavehei

    2015-03-01

    Full Text Available Background and Objectives: The group of 6-12 year-old students are the main target of oral health programs due to the high prevalence of dental caries and the formation of permanent teeth during this age and the lifestyle-shaping nature of the period. Schools provide the easiest and most effective means of accessing this group. The present study was conducted to examine the impact of school-based interventions on improved oral health in 6-12 year-old students. Materials and Methods: The present systematic review searched for its English and Persian keywords in databases such as the Scopus, Proquest, Science Direct, Pubmed, Springer, Biomed Central, Google Scholar, IranMedex and SID and examined studies published between January 2004 and September 2014 about educational interventions aiming to prevent oral diseases and promote associated health behaviors in students. Results: The 17 studies selected for examination were divided into two categories: first, assessing an education based on self-care behaviors and preventive services second, assessing an education based on self-care behaviors only. Those interventions that were consistent in nature, involved the parents and the school personnel, used behavior change models, used a combination of several training methods, used practical experiences and provided preventive services were more effective in promoting knowledge and health behaviors and reducing dental caries and plaque in this group of children. Conclusion: Providing consistent community-based education, using a combination of several organized educational programs, following up on the children's progress, using behavior change theories and models and providing prevention services are the most effective measures for achieving the desired goals.

  7. (Dy0.5Er0.5)Al2: A large magnetocaloric effect material for low-temperature magnetic refrigeration

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.; Takeya, H.; Moorman, J.O.; Pecharsky, V.K.

    1994-01-01

    The low-temprature heat capacity and ac and dc magnetic properties of (Dy 0.5 Er 0.5 )Al 2 have been studied as a function of magnetic fields up to ∼10 T. The magnetocaloric effect in (Dy 0.5 Er 0.5 )Al 2 is 30% larger than that of the prototype material, GdPd. Magnetic measurements show that there is no measurable magnetic hysteresis above ∼17 K. These results suggest that (Dy 0.5 Er 0.5 )Al 2 would be a significantly better magnetic refrigerant than GdPd

  8. Magnetic properties and EXAFS study of nanocrystalline Fe2Mn0.5Cu0.5Al synthesized using mechanical alloying technique

    International Nuclear Information System (INIS)

    Nanto, Dwi; Yang, Dong-Seok; Yu, Seong-Cho

    2014-01-01

    Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has been synthesized by the mechanical alloying technique and studied as a function of milling time. Alloy nature of Fe 2 Mn 0.5 Cu 0.5 Al was observed in a sample milled for 96 h. The magnetic saturation is 4.0 μ B /f.u., which coincidently follows Slater–Pauling rule at 5 K. Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has enhanced saturate magnetization compared to any other fabrication of Fe 2 MnAl reported. Cu element plays an important role in site competes with other elements and may result in the enhancement of saturate magnetization. In accordance to the magnetic results and EXAFS pattern, it was revealed that the dynamics of magnetic properties were confirmed as structural changes of nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al

  9. Microstructure research for ferroelectric origin in the strained Hf0.5Zr0.5O2 thin film via geometric phase analysis

    Science.gov (United States)

    Bi, Han; Sun, Qingqing; Zhao, Xuebing; You, Wenbin; Zhang, David Wei; Che, Renchao

    2018-04-01

    Recently, non-volatile semiconductor memory devices using a ferroelectric Hf0.5Zr0.5O2 film have been attracting extensive attention. However, at the nano-scale, the phase structure remains unclear in a thin Hf0.5Zr0.5O2 film, which stands in the way of the sustained development of ferroelectric memory nano-devices. Here, a series of electron microscopy evidences have illustrated that the interfacial strain played a key role in inducing the orthorhombic phase and the distorted tetragonal phase, which was the origin of the ferroelectricity in the Hf0.5Zr0.5O2 film. Our results provide insight into understanding the association between ferroelectric performances and microstructures of Hf0.5Zr0.5O2-based systems.

  10. Enhanced Microwave Absorption and Surface Wave Attenuation Properties of Co0.5Ni0.5Fe2O4 Fibers/Reduced Graphene Oxide Composites

    Directory of Open Access Journals (Sweden)

    Yinrui Li

    2018-03-01

    Full Text Available Co0.5Ni0.5Fe2O4 fibers with a diameter of about 270 nm and a length of about 10 μm were synthesized by a microemulsion-mediated solvothermal method with subsequent heat treatment. The Co0.5Ni0.5Fe2O4 fibers/reduced graphene oxide (RGO composite was prepared by a facile in-situ chemical reduction method. The crystalline structures and morphologies were investigated based on X-ray diffraction patterns and scanning electron microscopy. Magnetization measurements were carried out using a vibrating sample magnetometer at room temperature. Co0.5Ni0.5Fe2O4 fibers/RGO composites achieve both a wider and stronger absorption and an adjustable surface wave attenuation compared with Co0.5Ni0.5Fe2O4 fibers, indicating the potential for application as advanced microwave absorbers.

  11. Effect of warming bupivacaine 0.5% on ultrasound-guided axillary plexus block. Randomized prospective double-blind study.

    Science.gov (United States)

    Trabelsi, W; Ben Gabsia, A; Lebbi, A; Sammoud, W; Labbène, I; Kchelfi, S; Ferjani, M

    2017-02-01

    To evaluate the effect of warming bupivacaine 0.5% on ultrasound-guided axillary brachial plexus block. Prospective, randomized, double-blind. Eighty patients undergoing elective or emergency surgery beyond the distal third of the upper limb were divided into two groups of 40 patients: the warm group received 15mL bupivacaine 0.5% heated to 37°C; the cold group received 15mL 0.5% bupivacaine stored for at least 24hours in the lower compartment of a refrigerator at 13-15°C. Onset and duration of sensory and motor blocks were evaluated every 5minutes for 40minutes. Postoperative pain was evaluated at 1, 3, 6, 12 and 24hours. Effective analgesia time was recorded as the interval between anesthetic injection and the first analgesia requirement (VAS>30mm). Time to onset of sensory and motor block was significantly shorter in the warm group, and mean duration of sensory and motor block and of postoperative analgesia significantly longer. Warming bupivacaine 0.5% to 37°C accelerated onset of sensory and motor block and extended action duration. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. Influence of lanthanum on the physico-chemical properties of solid solutions GeS0.5Se0.5

    International Nuclear Information System (INIS)

    Murquzov, M.I.; Alekperov, A.S.; Bayramov, R.B.

    2010-01-01

    By the methods of physical-chemical analysis (X-ray, MSA, as well as measurement of microhardness and density determination) the influence of La on the physico-chemical properties of solid solutions (GeS 0 .5Se 0 .5) 1 -x(La) x was studied and its microdiagram was plotted. At room temperature the GeS 0 .5Se 0 .5 based solid solution extent 4 at. percent of La. The dependence of lanthane microhardness was studied

  13. Unique dielectric features of a ceramic-semiconductor nanocomposite MgNb2O6 + 0.25Zn0.5Cd0.5S

    Science.gov (United States)

    Pukazhselvan, D.; Selvaraj, Nivas Babu; Bdikin, Igor; Saravanan, R. Sakthi Sudar; Jakka, Suresh Kumar; Soares, M. J.; Fagg, Duncan Paul

    2017-12-01

    The present communication deals with the optical/dielectric characteristics of MgNb2O6 + 0.25Zn0.5Cd0.5S nanocomposite (10-30 nm) mixture. Zn0.5Cd0.5S (size ∼10 nm) was synthesized by microwave assisted solvo-thermal method. Monophase magnesium niobate (MN) nanoparticles (10-20 nm) were synthesized in a single step by mechanochemical treatment of MgO + Nb2O5 under dry N2 atmosphere. The nanocomposite, MgNb2O6 + 0.25Zn0.5Cd0.5S, was prepared by mechanical admixing of MgNb2O6 and Zn0.5Cd0.5S taken in 4:1 molar ratio. The photoluminescence study shows violet, yellow and orange-red emissions by the MgNb2O6 + 0.25Zn0.5Cd0.5S composite. The observed dielectric constant value (ε) for MgNb2O6 + 0.25Zn0.5Cd0.5S is only 4.7, which is ∼5 times smaller than the ε value of MgNb2O6 while a dielectric loss for the composite being closer to zero ensures promising commercial applications.

  14. Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

    International Nuclear Information System (INIS)

    Sungkono; Siti Aidah

    2015-01-01

    Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

  15. Ferromagnetic half-metallic characteristic in bulk Ni 0.5M 0.5O (M=Cu, Zn and Cd): A GGAU study

    KAUST Repository

    Mi, Wenbo

    2012-07-01

    Ferromagnetic half metallicity with a high spin polarization of 100% was predicted in the bulk Ni 0.5Cu 0.5O using density-functional theory method. The band gap of majority spin is 3.45 eV for Ni 0.5Cu 0.5O. The density of states of minority spin at the Fermi level are mainly from Cu 3d and O 2p in the Ni 0.5Cu 0.5O. The magnetic moments are from Ni 3d states. Ni 0.5Zn 0.5O and Ni 0.5Cd 0.5O systems are ferromagnetic insulators, but the magnetic moment of Ni 2 ions is enhanced by the Zn and Cd incorporation. Therefore, Ni 0.5Cu 0.5O is the potential candidate for spintronics devices because of the predicted high spin polarization. © 2012 Elsevier Ltd. All rights reserved.

  16. Ferromagnetic half-metallic characteristic in bulk Ni 0.5M 0.5O (M=Cu, Zn and Cd): A GGAU study

    KAUST Repository

    Mi, Wenbo; Yang, Hua; Cheng, Yingchun; Bai, Haili

    2012-01-01

    Ferromagnetic half metallicity with a high spin polarization of 100% was predicted in the bulk Ni 0.5Cu 0.5O using density-functional theory method. The band gap of majority spin is 3.45 eV for Ni 0.5Cu 0.5O. The density of states of minority spin at the Fermi level are mainly from Cu 3d and O 2p in the Ni 0.5Cu 0.5O. The magnetic moments are from Ni 3d states. Ni 0.5Zn 0.5O and Ni 0.5Cd 0.5O systems are ferromagnetic insulators, but the magnetic moment of Ni 2 ions is enhanced by the Zn and Cd incorporation. Therefore, Ni 0.5Cu 0.5O is the potential candidate for spintronics devices because of the predicted high spin polarization. © 2012 Elsevier Ltd. All rights reserved.

  17. Crystal structure and optical absorption spectra of Ga0.5Fe0.5InS3 and Ga0.5Fe0.25In1.25S3 crystals

    International Nuclear Information System (INIS)

    Gusejnov, G.G.; Musaeva, N.N.; Kyazumov, M.G.; Asadova, I.B.; Aliev, O.M.

    2003-01-01

    Single crystals of Ga 0.5 Fe 0.5 InS 3 are grown by the method of chemical gas-transport reactions and those of Ga 0.5 Fe 0.25 In 1.25 S 3 - by Bridgman method. X-ray diffraction studies reveal that they crystallize in trigonal and rhombohedral systems with lattice parameters of a = 3.796 x 2 A, c = 12.210 A, P3m1; a = 3.786 x 2 A, c = 36.606 A, R3m, respectively. An optical absorption edge in a wide range of photon energy and an energy gap width are determined: E g = 1.885 eV for Ga 0.5 Fe 0.5 InS 3 and E g 1.843 eV for Ga 0.5 Fe 0.25 In 1.25 S 3 [ru

  18. UV Light-Driven Photodegradation of Methylene Blue by Using Mn0.5Zn0.5Fe2O4/SiO2 Nanocomposites

    Science.gov (United States)

    Indrayana, I. P. T.; Julian, T.; Suharyadi, E.

    2018-04-01

    The photodegradation activity of nanocomposites for 20 ppm methylene blue solution has been investigated in this work. Nanocomposites Mn0.5Zn0.5Fe2O4/SiO2 have been synthesized using coprecipitation method. The X-ray diffraction (XRD) pattern confirmed the formation of three phases in sample Mn0.5Zn0.5Fe2O4/SiO2 i.e., Mn0.5Zn0.5Fe2O4, Zn(OH)2, and SiO2. The appearance of SiO2 phase showed that the encapsulation process has been carried out. The calculated particles size of Mn0.5Zn0.5Fe2O4/SiO2 is greater than Mn0.5Zn0.5Fe2O4. Bonding analysis via vibrational spectra for Mn0.5Zn0.5Fe2O4/SiO2 confirmed the formation of bonds Me-O-Si stretching (2854.65 cm-1) and Si-O-Si asymmetric stretching (1026.13 cm-1). The optical gap energy of Mn0.5Zn0.5Fe2O4/SiO2 was smaller (2.70 eV) than Mn0.5Zn0.5Fe2O4 (3.04 eV) due to smaller lattice dislocation and microstrain that affect their electronic structure. The Mn0.5Zn0.5Fe2O4/SiO2 showed high photodegradation ability due to smaller optical gap energy and the appearance of SiO2 ligand that can easily attract dye molecules. The Mn0.5Zn0.5Fe2O4/SiO2 also showed high degradation activity even without UV light radiation. The result showed that photodegradation reaction doesn’t follow pseudo-first order kinetics.

  19. Valence behavior of Eu-ions in intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Abhishek, E-mail: apandey@ameslab.gov [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Mazumdar, Chandan, E-mail: chandan.mazumdar@saha.ac.in [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Ranganathan, R. [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Raghavendra Reddy, V.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandawa Road, Indore (India)

    2011-12-15

    We have studied the valence behavior of rare-earth ions, in particular Eu-ions, in a cubic intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} which is a homogeneous solid solution of two mixed-valent compounds CePd{sub 3} and EuPd{sub 3}B. Results of {sup 151}Eu Moessbauer spectroscopic measurements show that two different valence states, i.e., divalent- and trivalent-like states of Eu-ions exist in the compound. The possible reason for the observed heterogeneous valency vis-a-vis the variation in the chemical environment and the number of nearest-neighbor B atoms surrounding the Eu-ions has been discussed. Our results demonstrate that B incorporation in such Eu-based cubic intermetallic compounds leads to a situation where heterogeneous-valence state of Eu-ions is an energetically favorable ground state. - Highlights: > Intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} crystallizes in a single phase. > Eu-ions in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} are charge-ordered compared to +2.3 valency in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}. > B incorporation makes charge-ordered state of Eu-ions energetically more favorable. > Nearest-neighbor chemical environment affects the Eu valency.

  20. Electronic structure and optical properties of LiGa0.5In0.5Se2 single crystal, a nonlinear optical mid-IR material

    Science.gov (United States)

    Lavrentyev, A. A.; Gabrelian, B. V.; Vu, Tuan V.; Isaenko, L. I.; Yelisseyev, A. P.; Khyzhun, O. Y.

    2018-06-01

    Measurements of X-ray photoelectron core-level and valence-band spectra for pristine and irradiated with Ar+ ions surfaces of LiGa0.5In0.5Se2 single crystal, novel nonlinear optical mid-IR selenide grown by a modified vertical Bridgman-Stockbarger technique, are reported. Electronic structure of LiGa0.5In0.5Se2 is elucidated from theoretical and experimental points of view. Notably, total and partial densities of states (DOSs) of the LiGa0.5In0.5Se2 compound are calculated based on density functional theory (DFT) using the augmented plane wave + local orbitals (APW + lo) method. In accordance with the DFT calculations, the principal contributors to the valence band are the Se 4p states, making the main input at the top and in the upper part of the band, while its bottom is dominated by contributions of the valence s states associated with Ga and In atoms. The theoretical total DOS curve peculiarities are found to be in excellent agreement with the shape of the X-ray photoelectron valence-band spectrum of the LiGa0.5In0.5Se2 single crystal. The bottom of the conduction band of LiGa0.5In0.5Se2 is formed mainly by contributions of the unoccupied Ga 4s and In 5s states in almost equal proportion, with somewhat smaller contributions of the unoccupied Se 4p states as well. Our calculations indicate that the LiGa0.5In0.5Se2 compound is a direct gap semiconductor. The principal optical constants of LiGa0.5In0.5Se2 are calculated in the present work.

  1. Constructing Cd0.5Zn0.5S@ZIF-8 nanocomposites through self-assembly strategy to enhance Cr(VI) photocatalytic reduction.

    Science.gov (United States)

    Qiu, Jianhao; Zhang, Xiong-Fei; Zhang, Xingguang; Feng, Yi; Li, Yuxin; Yang, Lvye; Lu, Haiqiang; Yao, Jianfeng

    2018-05-05

    A novel and highly efficient photocatalyst of Cd 0.5 Zn 0.5 S@ZIF-8 nanocomposite has been developed by a facile self-assembly strategy. This is the first report on the application of Cd x Zn 1-x S and metal-organic framework (MOF) nanocomposite as photocatalysts for the reduction of Cr(VI). The resulting Cd 0.5 Zn 0.5 S@ZIF-8 exhibited higher photocatalytic activity than that of pristine Cd 0.5 Zn 0.5 S and ZIF-8. Particularly, the CZS@Z60 composite with 60 wt% of ZIF-8 exhibited a photocatalytic activity that is about 1.6 times as high as that of Cd 0.5 Zn 0.5 S. The dominant reason for the improved photocatalytic reduction potential is proved to be the newly-formed interfacial SZn bonds that firmly connect Cd 0.5 Zn 0.5 S and ZIF-8 and substantially improve the separation efficiency of photo-excited electrons and holes. The newly-formed chemical bonds are confirmed by XPS analyses, and the prolonged lifetime of photo-excited electrons is evidenced by the electrochemical measurement of photocurrent, which shows that the photocurrent on Cd 0.5 Zn 0.5 S@ZIF-8 is much higher than that of Cd 0.5 Zn 0.5 S and ZIF-8. This study clearly demonstrates that the MOF-based composite nanomaterials hold great promises for applications in the field of environmental remediation and for design of novel photocatalytic materials. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Efficient photocatalytic removal of nitric oxide with hydrothermal synthesized Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn; Lu, Gang; Lee, Shuncheng

    2014-11-15

    Highlights: • Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were prepared via a facile hydrothermal route. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior photocatalytic performances for the removal of nitric oxide. • The Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes show potential for indoor and outdoor air purification. - Abstract: In this study, Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes were synthesized with a facile hydrothermal method using TiO{sub 2} P25 (Degussa) and bismuth citrate (BiC{sub 5}H{sub 6}O{sub 7}) as precursors in concentrated NaOH and ammonia alkali solution. The samples were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The as-prepared Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes exhibited superior activity for photocatalytic removal of gaseous nitric oxide (NO) over TiO{sub 2} P25 (Degussa) under simulated solar-light irradiation, the NO removal rate can reach as high as ca. 200 ppb·min{sup −1} over the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes in a continuous reactor with an initial NO concentration of 400 ppb. The intrinsic hollow-nanotube structure of the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} photocatalysts contributes to its superior activity under simulated solar light. This work provides a facile route to prepare Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes and suggests that the Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} nanotubes are ideal candidates for efficient removal of nitric oxide in indoor/outdoor air.

  3. AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

    Science.gov (United States)

    Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

    2018-05-01

    Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

  4. Superconductivity in REO0.5F0.5BiS2 with high-entropy-alloy-type blocking layers

    Science.gov (United States)

    Sogabe, Ryota; Goto, Yosuke; Mizuguchi, Yoshikazu

    2018-05-01

    We synthesized new REO0.5F0.5BiS2 (RE: rare earth) superconductors with high-entropy-alloy-type (HEA-type) REO blocking layers. The lattice constant a systematically changed in the HEA-type samples with the RE concentration and the RE ionic radius. A sharp superconducting transition was observed in the resistivity measurements for all the HEA-type samples, and the transition temperature of the HEA-type samples was higher than that of typical REO0.5F0.5BiS2. The sharp superconducting transition and the enhanced superconducting properties of the HEA-type samples may indicate the effectiveness of the HEA states of the REO blocking layers in the REO0.5F0.5BiS2 system.

  5. KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr- 0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN

    Directory of Open Access Journals (Sweden)

    Sungkono Sungkono

    2015-07-01

    Full Text Available KARAKTERISTIK MIKROSTRUKTUR DAN FASA PADUAN Zr-0,3%Nb-0,5%Fe-0,5%Cr PASCA PERLAKUAN PANAS DAN PENGEROLAN DINGIN. Logam paduan Zr-Nb-Fe-Cr dikembangkan sebagai material kelongsong elemen bakar dengan fraksi bakar tinggi untuk reaktor daya maju. Dalam penelitian ini telah dibuat paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr yang mendapat perlakuan panas pada temperatur 650 dan 750°C dengan waktu penahanan 1–2 jam. Tujuan penelitian adalah mendapatkan karakter paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas dan pengerolan dingin yaitu mikrostruktur, struktur kristal dan fasa-fasa yang ada dalam paduan. Hasil penelitian menunjukkan bahwa paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650ºC, 1-2 jam mempunyai struktur butir ekuiaksial dengan ukuran butir bertambah besar seiring dengan bertambahnya waktu penahanan. Sementara itu, pasca perlakuan panas (750ºC, 1-2 jam terjadi perubahan mikrostruktur paduan dari butir ekuiaksial dan kolumnar menjadi butir ekuiaksial lebih besar. Paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr pasca perlakuan panas (650°C, 1 jam dan (750°C, 1 jam tidak dapat dirol dingin dengan reduksi tebal 5 – 10%, sedangkan pasca perlakuan panas (650ºC, 2 jam dan (750°C, 1.5-2 jam mampu menerima deformasi dingin dengan reduksi ketebalan 5-10% tanpa mengalami keretakan. Senyawa Zr2Fe, ZrCr2 dan FeCr teridentifikai dari hasil uji kristalografi paduan Zr-0,3%Nb-0,5%Fe-0,5%Cr.   MICROSTRUCTURE AND PHASE CHARACTERISTICSOF Zr-0.3%Nb-0.5%Fe-0.5%Cr ALLOY POST HEAT TREATMENT AND COLD ROLLING. Zr-Nb-Fe-Cr alloys was developed as fuel elements cladding with high burn up for advanced power reactors. In this research has been made of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy were heat treated with varying temperatures at650 and 750°C for 1 until 2 hours. The objectives of this research was to obtain the character of Zr-0.3% Nb-0.5% Fe-0.5% Cr alloy post heat treatment and cold rolling, microstructure nomenclature, crystal structure and phases that presents in the

  6. Different effect of quenching temperature on Fe1+σTe0.5Se0.5 and β-FeSe

    Directory of Open Access Journals (Sweden)

    Zhongnan Guo

    2015-02-01

    Full Text Available In this work, we have demonstrated a different effect on Fe1+σTe0.5Se0.5 and β-FeSe by changing the quenching temperature. Tc is clearly reduced in Fe1+σTe0.5Se0.5 after increasing the quenching temperature from 300 °C to 500 °C, while that of β-FeSe is almost unchanged. Structure refinement indicates that after quenched at 500 °C, FeTe4 tetrahedron exhibits an expansion with the stretched Fe-Te bond, together with the increased amount of interstitial iron. These particular changes on structure are believed to be responsible for the suppression of superconductivity in Fe1+σTe0.5Se0.5.

  7. Structure ordering effect on dielectric properties of PbIn/sub 0. 5/Nb/sub 0. 5/O/sub 3/ crystals

    Energy Technology Data Exchange (ETDEWEB)

    Turik, A V; Kupriyanov, M F; Zhestkov, B F

    1985-09-01

    Results are presented of dielectric and X-ray diffraction investigations into the PbIn/sub 0.5/Nb/sub 0.5/O/sub 3/ monocrystals of PbB/sub 0.5/'B/sub 0.5/''O/sub 3/ series (B'=ScIn, B''=Nb, Ta) annealed during 5 hours at 500 deg C. It is shown that ordering in the B'-cation position in crystals influences the character of alternation of phases and physical properties. The PbIn/sub 0.5/Nb/sub 0.5/O/sub 3/ crystals may be either in rhombohedral ferro- or zhombic antiferroelectric phases depending on thermal prehistory.

  8. Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser

    Science.gov (United States)

    Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi

    2018-06-01

    In this work, we fabricate the Mo0.5W0.5S2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo0.5W0.5S2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm‑2. The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo0.5W0.5S2 SAs.

  9. Structure analysis of mutually incommensurate composite crystal (Ca0.5Y0.5)0.8CuO2

    International Nuclear Information System (INIS)

    Gotoh, Y.; Yamaguchi, I.; Takeya, S.; Fujihisa, H.; Honda, K.; Ito, T.; Oka, K.; Yamaguchi, H.

    2006-01-01

    Single-crystal X-ray structure analysis of mutually incommensurate (Ca 0.5 Y 0.5 ) 0.8 CuO 2 , 'Ca 2 Y 2 Cu 5 O 1 ' has been performed by the composite approach which leads to average substructures and their relative arrangement. The composite crystal structure of (Ca 0.5 Y 0.5 ) 0.8 CuO 2 has the CuO 2 substructure and the Ca 0.5 Y 0.5 substructure. The CuO 2 substructure with a 1 = 10.598(2) A, b = 6.189(2) A, c 1 = 2.825(2) A, β 1 = 90.19(4) o , V 1 = 185.4(1) A 3 , Z = 4 and space group F2/m has the plane of edge-shared one-dimensional CuO 2 chains along the c-axis. The Ca 0.5 Y 0.5 substructure with a 2 = 10.629(2) A, b = 6.189(2) A, c 2 3.517(1) A, β 2 = 94.36(3) o , V 2 = 230.7(1) A 3 , Z = 4 and space group F2/m forms the sheet of (Ca, Y) atoms in the ac-plane. By considering (3 + 1)-dimensional superspace group symmetry, it is concluded that the incommensurate composite crystal structure of (Ca 0.5 Y 0.5 ) 0.8 CuO 2 should be described by the combination of F2/m for the CuO 2 substructure and F2/c for the Ca 0.5 Y 0.5 substructure. The composite approach has made clear that the plane of CuO 2 chains and the sheet of (Ca, Y) atoms stack alternately to form a mutually incommensurate composite crystal with layered substructures

  10. Comparative Investigation of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 Cathode Materials Synthesized by Using Different Lithium Sources

    Directory of Open Access Journals (Sweden)

    Peng-Bo Wang

    2018-05-01

    Full Text Available Lithium-rich manganese-based cathode materials has been attracted enormous interests as one of the most promising candidates of cathode materials for next-generation lithium ion batteries because of its high theoretic capacity and low cost. In this study, 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 materials are synthesized through a solid-state reaction by using different lithium sources, and the synthesis process and the reaction mechanism are investigated in detail. The morphology, structure, and electrochemical performances of the material synthesized by using LiOH·H2O, Li2CO3, and CH3COOLi·2H2O have been analyzed by using Thermo gravimetric analysis (TGA, X-ray diffraction (XRD, Scanning electron microscope (SEM, Transmission electron microscope (TEM, X-ray photoelectron spectroscopy (XPS, and electrochemical measurements. The 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 material prepared by using LiOH·H2O displays uniform morphology with nano particle and stable layer structure so that it suppresses the first cycle irreversible reaction and structure transfer, and it delivers the best electrochemical performance. The results indicate that LiOH·H2O is the best choice for the synthesis of the 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 material.

  11. Theoretical investigations on the elastic and thermodynamic properties of Ti2AlC0.5N0.5 solid solution

    International Nuclear Information System (INIS)

    Du, Y.L.; Sun, Z.M.; Hashimoto, H.; Barsoum, M.W.

    2009-01-01

    We have performed theoretical studies on the elastic and thermodynamic properties of the solid solution: Ti 2 AlC 0.5 N 0.5 . The lattice parameters, elastic constants, bulk, shear, Young's moduli, Poisson's ratio and Debye temperature were calculated and compared with those of the end members, Ti 2 AlC and Ti 2 AlN. The temperature dependence of the bulk moduli, thermal expansion coefficient and specific heats of Ti 2 AlC 0.5 N 0.5 were obtained from the quasi-harmonic Debye model. The calculated elastic and thermodynamic properties were compared with experimental data.

  12. The continuous-wave passive mode-locking operation of a diode-pumped mixed Nd:Lu0.5Y0.5VO4 laser

    International Nuclear Information System (INIS)

    Huang, H-T; Xu, J-L; He, J-L; Zhang, S-Y; Xu, J-Q; Zhao, B

    2011-01-01

    We reported a continuous-wave (CW) passively mode-locked Nd:Lu 0.5 Y 0.5 VO 4 laser at 1064 nm. A partially reflective semiconductor saturable absorber mirror was exploited in the Z-typed resonator. The Nd:Lu 0.5 Y 0.5 VO 4 laser generated CW mode-locked pulses with an average output power of 860 mW, a repetition rate of 53.7 MHz, and a pulse duration of 8.7 ps

  13. Influence of lanthanium atoms on the physico-chemical properties of GeS0,5Se0,5 solid solutions

    International Nuclear Information System (INIS)

    Murguzov, M.I.; Alakbarov, A.S.; Bayramov, R.B.

    2010-01-01

    By the methods of physical-chemical analysis (DTA, X-ray, MSA, as well as measurement of microhardness and density determination) the influence of La on the physico-chemical properties of solid solutions (GeS 0 ,5Se 0 ,5) 1 -x(La) x was studied and its microdiagram was plotted. At room temperature the GeS 0 ,5Se 0 ,5 based solid solid solution extent to 4 at. percent La. The dependence of lanthane microhardness was studied

  14. Ni_0_,_5Zn_0_,_5Fe_2O_3 ferrite synthesized by combustion and Pechini method for use in nanomedicine: methods evaluation

    International Nuclear Information System (INIS)

    Albuquerque, I.L.T. de; Nascimento, A.L.C.; Costa, A.C.F.M.

    2016-01-01

    The objective of this work was to synthesize the Ni0.5Zn0.5Fe2O3 ferrite by combustion reaction and Pechini method, and to evaluate structural characteristics and magnetic behavior for its use in nanomedicine. The synthesized ferrite was characterized by DRX, BET, TG and magnetic properties. According to the results of XRD, the Ni_0_,_5Zn_0_,_5Fe_2O_3 ferrite synthesized by both methods presented nano crystallite sizes, high crystallinity, surface area, stable at high temperatures and with high saturation magnetization, being higher in the ferrite synthesized by combustion reaction. Both methods produced materials that could be used in nanomedicine

  15. Microstructure and phase analysis of 0.5Cr-0.5Mo-0.25V creep-resistant steels after long-term service

    Czech Academy of Sciences Publication Activity Database

    Výrostková, A.; Svoboda, Milan; Homolová, V.; Falat, L.; Kepič, J.

    2011-01-01

    Roč. 105, - (2011), s. 452-454 ISSN 0009-2770 Institutional research plan: CEZ:AV0Z20410507 Keywords : low-alloy steels * microstructure * phase analysis Subject RIV: JG - Metallurgy Impact factor: 0.529, year: 2011

  16. Magnetoelectric effect of (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 composites

    Science.gov (United States)

    Rahaman, Md. D.; Saha, S. K.; Ahmed, T. N.; Saha, D. K.; Hossain, A. K. M. Akther

    2014-12-01

    The magnetoelectric composites with chemical compositions (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σAC) vs. log(ω2) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm-1 Oe-1 is obtained for x=20 wt% at room temperature.

  17. Structural aspects of B2O3-substituted (PbO)0.5(SiO2)0.5 glasses

    International Nuclear Information System (INIS)

    Sudarsan, V.; Kulshreshtha, S.K.; Shrikhande, V.K.; Kothiyal, G.P.

    2002-01-01

    Lead borosilicate glasses having general formulae (PbO) 0.5-x (SiO 2 ) 0.5 (B 2 O 3 ) x with 0.0≤x≤0.4 and (PbO) 0.5 (SiO 2 ) 0.5-y (B 2 O 3 ) y with 0.0≤y≤0.5 have been prepared by a conventional melt-quench method and characterized by 29 Si, 11 B magic angle spinning (MAS) NMR techniques and infrared spectroscopy, as regards their structural features. From 29 Si NMR results, it has been inferred that with increasing concentration of boron oxide, (PbO) 0.5-x (SiO 2 ) 0.5 (B 2 O 3 )x glasses exhibit a systematic increase in the number of Q 4 structural units of Si at the expense of Q 2 structural units, along with the formation of Si-O-B linkages. On the other hand, for (PbO) 0.5 (SiO 2 ) 0.5-y (B 2 O 3 ) y glasses, there is no direct interaction between SiO 2 and B 2 O 3 in the glass network, as revealed by the 29 Si MAS NMR studies. Boron exists in both trigonal and tetrahedral configurations for these two series of glasses and for the (PbO) 0.5 (SiO 2 ) 0.5-y (B 2 O 3 ) y series of glasses; the relative concentration of these two structural units remains almost constant with increasing B 2 O 3 concentration. In contrast, for (PbO) 0.5-x (SiO 2 ) 0.5 (B 2 O 3 ) x glasses, there is a slight increase in the number of BO 3 structural units above x = 0.2, as there is a competition between SiO 2 and B 2 O 3 for interaction with Pb 2+ , thereby leading to the formation of BO 3 structural units. For both series of glasses, the thermal expansion coefficient is found to decrease with increasing B 2 O 3 concentration, the effect being more pronounced for the (PbO) 0.5-x (SiO 2 ) 0.5 (B 2 O 3 ) x series of glasses due to the increased concentration of Q 4 structural units of silicon and better cross-linking as a result of the formation of Si-O-B-type linkages. (author)

  18. Neutron diffraction and magnetization studies of Tb0.5Er0.5 single crystal in an external magnetic field

    International Nuclear Information System (INIS)

    Kosugi, T.; Yamamoto, N.

    1999-01-01

    Complete text of publication follows. The rare earth Tb 0.5 Er 0.5 alloy exhibits a tilted helix at low temperatures [1]. However, the magnetic structures of Tb 0.5 Er 0.5 and the magnetization processes of the tilted helix are not clear. Neutron diffraction experiments in external magnetic fields and magnetization measurements of Tb 0.5 Er 0.5 single crystal have been performed. At zero magnetic field, the Tb 0.5 Er 0.5 alloy exhibited a normal helix below 170 K, a bunching normal helix below about 28 K, and finally a bunching tilted helix below about 25 K. Below about 60 K, the helical pitch 30 deg showed a lock-in feature. The magnetization measurements at low temperatures showed a four-step magnetic transition. The results are presented as a magnetic field-temperature (H-T) phase diagram. (author) [1] H. Fujii et al., J. Phys. Soc. Jpn. 50 (1981) 2939

  19. Topotactic reduction and reoxidation of hexagonal RCu0.5Ti0.5O3 (R = Y, Eu-Lu) Phases

    International Nuclear Information System (INIS)

    Jiang, Peng; Berthelot, Romain; Li, Jun; Sleight, A.W.; Subramanian, M.A.

    2013-01-01

    Highlights: ► Topotactic reduction of hexagonal RCu 0.5 Ti 0.5 O 3 phases is performed. ► TGA and magnetism indicate a formula of RCu 0.5 Ti 0.5 O 2.78 for the reduced phase. ► Topotactic reoxidation occurs on heating these phases to 400 °C in air. - Abstract: Hexagonal AMO 2 and AMO 3 phases have the same basic structure, and intermediate compositions for this structure have been prepared by topotactic oxidation of AMO 2 phases such as RCuO 2 , where R is a trivalent rare earth cation. We now find that such intermediate phases can also be prepared by topotactic reduction of hexagonal RCu 0.5 Ti 0.5 O 3 (R = Y, Tb-Lu) phases. Our TGA and magnetic susceptibility studies indicate a formula of RCu 0.5 Ti 0.5 O 2.78 for these reduced phases. Topotactic reoxidation occurs on heating these phases to 400 °C in air

  20. Topotactic reduction and reoxidation of hexagonal RCu{sub 0.5}Ti{sub 0.5}O{sub 3} (R = Y, Eu-Lu) Phases

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Peng, E-mail: jiangp@onid.orst.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Berthelot, Romain, E-mail: berthelot.rom@gmail.com [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Li, Jun, E-mail: jli100@yahoo.com [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Sleight, A.W., E-mail: arthur.sleight@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States)

    2013-06-01

    Highlights: ► Topotactic reduction of hexagonal RCu{sub 0.5}Ti{sub 0.5}O{sub 3} phases is performed. ► TGA and magnetism indicate a formula of RCu{sub 0.5}Ti{sub 0.5}O{sub 2.78} for the reduced phase. ► Topotactic reoxidation occurs on heating these phases to 400 °C in air. - Abstract: Hexagonal AMO{sub 2} and AMO{sub 3} phases have the same basic structure, and intermediate compositions for this structure have been prepared by topotactic oxidation of AMO{sub 2} phases such as RCuO{sub 2}, where R is a trivalent rare earth cation. We now find that such intermediate phases can also be prepared by topotactic reduction of hexagonal RCu{sub 0.5}Ti{sub 0.5}O{sub 3} (R = Y, Tb-Lu) phases. Our TGA and magnetic susceptibility studies indicate a formula of RCu{sub 0.5}Ti{sub 0.5}O{sub 2.78} for these reduced phases. Topotactic reoxidation occurs on heating these phases to 400 °C in air.

  1. A new silver metaniobate semiconductor of Ag0.5La0.5Nb2O6 with defect-perovskite structure

    Science.gov (United States)

    Mi, Longqing; Feng, Yongyi; Cao, Lei; Xue, Mingqiang; Huang, Yanlin; Qin, Lin; Seo, Hyo Jin

    2018-03-01

    Silver-containing lanthanum metaniobate Ag0.5La0.5Nb2O6 nanoparticles were synthesized by sol-gel polymerized complex method. A typical defect-perovskite structure was confirmed by XRD Rietveld refinements. The surface characteristics of the sample were tested by SEM, TEM and EDS measurements. SEM and TEM show that the sample presents ball-like particles with the diameters of 100 nm to 400 nm. The sample shows both self-activated luminescence and photocatalytic activities. Ag0.5La0.5Nb2O6 has a direct transition with band energy of 2.85 eV. The Ag4d-O2p hybridization in the valence band contributes to the narrowed band gap. The luminescence properties of Ag0.5La0.5Nb2O6 have been investigated for the first time. The luminescence is characterized by two emission centers with maximum wavelength near 460 and 530 nm. The emission and excitation spectra, decay curves and the thermal quenching mechanism were discussed. Ag0.5La0.5Nb2O6 shows the efficient photocatalytic activities and the photodegradation rate for methylene blue dye (MB) can reach about 95% under visible light (> 420 nm) irradiation in 5 h. The trapped experiments for the active species were tested and discussed, which verified that rad OH radicals could be the major active species in photocatalysis.

  2. Various properties of the 0.6BaTiO3–0.4Ni0.5Zn0.5Fe2O4 ...

    Indian Academy of Sciences (India)

    2016-09-06

    Sep 6, 2016 ... This property pro- motes the magnetoelectric energy conversion and thus ... Wet mixing was done with ethanol to obtain a homogeneous powder mix- ... rite was prepared by mixing NiO, ZnO and Fe2O3 in. 0.5:0.5:1 molar ...

  3. High temperature study on the thermal properties of few-layer Mo0.5W0.5S2 and effects of capping layers

    Directory of Open Access Journals (Sweden)

    Hong Gu

    Full Text Available We investigated the thermal properties of few-layer Mo0.5W0.5S2 using a series of samples with different kinds of capping layers. Temperature-dependent Raman measurements were conducted in the range of 300–500 K, with power-dependent measurements also carried out. It indicated, for the few-layer Mo0.5W0.5S2, the temperature coefficients of the WS2-like E12g mode, MoS2-like E12g mode and A1g mode were −0.0155 cm−1/K, −0.0146 cm−1/K, and −0.0130 cm−1/K, respectively. And the thermal conductivity was estimated to be 44.8 W/mK. Moreover, the Mo0.5W0.5S2 samples coated with capping layers (ZrO2, HfO2 both showed a better thermal stability and a larger thermal conductivity than the one without. The results revealed that the capping layer should be an important factor in the thermal property. Keywords: Mo0.5W0.5S2, TMDs, Thermal properties, High temperature, Capping layers, Raman

  4. The determination of the enthalpy of formation and the enthalpy increment of Cd0.5 Te0.5 by Calvet calorimetry

    International Nuclear Information System (INIS)

    Agarwal, R.; Venugopal, V.; Sood, D.D.

    1993-01-01

    In the present study the enthalpy of formation of Cd 0.5 Te 0.5 compound at 785 K were determined from the two elements by direct reaction calorimetry using two different types of set-ups. The enthalpy increment values were measured by drop technique in Calvet calorimetry. (author). 3 refs., 4 tabs

  5. Large anisotropy in colossal magnetoresistance of charge orbital ordered epitaxial Sm0.5Ca0.5MnO3 films

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Sun, J.R.; Zhao, J.L.

    2009-01-01

    We investigated the structure and magnetotransport properties of Sm0.5Ca0.5MnO3 (SCMO) films epitaxially grown on (011)-oriented SrTiO3 substrates, which exhibited clear charge/orbital ordering transition. A significant anisotropy of ~1000 in the colossal magnetoresistance (CMR) effect was observ...

  6. Characters of alloy Zr-0.4%Mo-0.5%Fe-0.5%Cr post heat treatment and cold rolling

    International Nuclear Information System (INIS)

    Sungkono; Siti Aidah

    2014-01-01

    Research and development of Zr-Mo-Fe-Cr alloys aimed to obtain PWR fuel element structure material with high burn up. In this study of the Zr-0.4%Mo-0.5%Fe-0.5%Cr alloys was prepared from zirconium sponge, molybdenum, iron and chromium powder. The alloy were heat treated at varying temperatures of 650 and 750 °C and retention time of 1, 1.5 and 2 hours. The objectives of this research was to obtain effect of thickness reduction on the character of Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy. The results of this experiment showed that the microstructures of Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy after heat treatment and cold rolling exhibits that the higher of the thickness reduction has applied on the alloy caused the microstructure to evolve from deformed equiaxial grains into flat bar grains and then into deformed flat bar grains. However, the higher of the temperature and the retention time then the larger grain structures so that the cold rolling causes the shape of the grains structure into a flat bar with a relatively larger size which affects the lower hardness. The Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy after heat treatment (650-750°C; 1.5-2 hours) can undergo cold deformation without cracking at a thickness reduction between 5 to 15%. (author)

  7. Lead-free (K0.5Na0.5)NbO3 thin films by pulsed laser deposition driving MEMS-based piezoelectric cantilevers

    NARCIS (Netherlands)

    Nguyen, Duc Minh; Dekkers, Jan M.; Houwman, Evert Pieter; Vu, H.T.; Vu, Hung N.; Rijnders, Augustinus J.H.M.

    2016-01-01

    Thin film capacitors of the lead-free (K0.5Na0.5)NbO3 (KNN) with (100) orientation were grown on Pt/Ti/SiO2/SOI (silicon-on-insulator) substrates by pulsed laser deposition. The films are pure phases and do not show other crystal orientations. The remnant polarization Pr, saturation polarization

  8. Perovskites A/sub 2/sup(II)Bsub(0. 5)sup(I)Bsub(0. 5)sup(III)Wsup(VI)O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Roller, H; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-05-01

    Compounds of type A/sub 2/sup(II)Bsub(0.5)sup(I)Bsub(0.5)sup(III)Wsup(VI)O/sub 6/ can be obtained with Asup(II) = Ba; Bsup(I) = Li, Na and Bsup(III) = La, Nd, Sm, Gd, Y, In, Sc just as with Asup(II) = Sr; Bsup(I) = Li and Bsup(III) = La, Nd, Sm, Gd, Y, In (all cubic ordered perovskites). For the cubic perovskites Sr/sub 2/Nasub(0.5)Lasub(0.5)WO/sub 6/ and Sr/sub 2/Nasub(0.5)Ndsub(0.5)WO/sub 6/ additional superlattice reflections are observed (a approximately equal to 16.4 A). The compounds Sr/sub 2/Nasub(0.5)Bsub(0.5)sup(III)WO/sub 6/ crystallize with Bsup(III) = Sm, Gd in a monoclinic and with Bsup(III) = Y, In in a rhombic distorted perovskite lattice. For the perovskites with A = Sr - dependent on ionic radii of the B ions - two different lattice types are present.

  9. Electronic and magnetic properties of R0.5A0.5MnO3 compounds (R=Gd, Dy, Ho, Er; A=Sr, Ca)

    International Nuclear Information System (INIS)

    Terai, T.; Sasaki, T.; Kakeshita, T.; Fukuda, T.; Saburi, T.; Kitagawa, H.; Kindo, K.; Honda, M.

    2000-01-01

    Electronic and magnetic properties of the perovskitelike compounds of R 0.5 A 0.5 MnO 3 (R=Gd, Dy, Ho, Er; A=Sr, Ca) have been studied by measuring lattice parameter, electrical resistivity, magnetic susceptibility, and magnetization. All the Sr-doped compounds show a transition from a paramagnetic insulator to a spin-glass-like insulator at T g , even though the manganite La 0.5 Ca 0.5 MnO 3 , with nearly the same tolerance factor t, have been shown by others, to have different transitions. On the other hand, all the Ca-doped compounds show a charge-ordering transition at T CO and show a transition from a paramagnetic insulator to a canted antiferromagnetic insulator and/or a spin-glass-like insulator at T CA below T CO . These transition temperatures decrease with decreasing t. In the compound of Gd 0.5 Ca 0.5 MnO 3 , the collapse of the charge ordering has been observed under a pulsed high magnetic field of 45 T at 4.2 K. On the other hand, in the compound of Gd 0.5 Sr 0.5 MnO 3 , the magnetization process depends on the strength of magnetic field. These electronic and magnetic properties depend not only on the tolerance factor but also the variance (second moment) of the A-site ion radii distribution

  10. The temperature influence against conductivity of solid state electrolyte of (CuI)0,5(β-Al2O3)0,5

    International Nuclear Information System (INIS)

    Purwanto, -P; Kartini, -E; Purnama, Safei

    2004-01-01

    The solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 has been prepared by a solid state reaction, by mixing of CuI with β-Al 2 O 3 powders. The mixture was compacted and heated at the temperature 300 o C for 3 hours. The conductivity values of (CuI) 0,5 (β-Al 2 O 3 ) 0,5 increased with the temperature and frequency. The x ray diffraction peaks of the solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 are dominated by the peaks of CuI than the peaks of β-Al 2 O 3 . The activation energy of the solid electrolyte is relatively stable, with the range from 0.09 eV to 0.13 eV. The conductivities solid electrolyte (CuI) 0,5 (β-Al 2 O 3 ) 0,5 at room temperature and at 300 o C are 1.48 x 10 -5 S/cm and 8.33 x 10 -4 S/cm, respectively

  11. Photoluminescence of polycrystalline CuIn 0.5 Ga 0.5 Te 2 thin films grown by flash evaporation

    KAUST Repository

    Yandjah, L.; Bechiri, L.; Benabdeslem, M.; Benslim, N.; Amara, A.; Portier, X.; Bououdina, M.; Ziani, Ahmed

    2018-01-01

    Polycrystalline CuIn0.5Ga0.5Te2 films were deposited by flash evaporation from ingot prepared by reacting, in stoichiometric proportions, high purity Cu, In, Ga and Te elements in vacuum sealed quartz . The as-obtained films were characterized by X

  12. Structural and optical characteristics of nano-sized structure of Zn0.5Cd0.5S thin films prepared by dip-coating method

    International Nuclear Information System (INIS)

    Rafea, M. Abdel; Farag, A.A.M.; Roushdy, N.

    2009-01-01

    In this work, a stoichiometry Zn 0.5 Cd 0.5 S nano-structured powder was synthesized. Thin films of different thicknesses of Zn 0.5 Cd 0.5 S were prepared by dip-coating method onto glass substrates. The X-ray diffraction analysis of the prepared powder and films were performed to investigate the crystalline structure. Some structural parameters such as the mean crystallite size and the internal lattice strain were calculated. The composition analysis was made by the energy dispersive X-ray technique, EDX. Scanning electron micrographs, SEM showed that the prepared films are nearly homogeneous and consists of nearly parallel surfaces and the thickness was determined by the cross section imaging. The transmission spectra, T(λ), of the films at normal incidence of light were obtained in the spectral region 190-1100 nm. The optical constants of Zn 0.5 Cd 0.5 S films were determined using the interference maxima and minima of the transmission spectrum. The dispersion of refractive index was discussed in terms of the single-oscillator model and the important oscillating parameters were determined. The dependence of absorption coefficient on the photon energy was determined and the analysis of the result showed that the optical transition in Zn 0.5 Cd 0.5 S is allowed and indirect. The thickness dependence of the obtained optical parameters was also considered.

  13. Synthesis, structure and electrochemical properties of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Fedotov, Stanislav S. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow (Russian Federation); Kuzovchikov, Sergey M.; Khasanova, Nellie R.; Drozhzhin, Oleg A.; Filimonov, Dmitriy S. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Karakulina, Olesia M.; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Abakumov, Artem M. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow (Russian Federation); EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Antipov, Evgeny V. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation)

    2016-10-15

    LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by {sup 57}Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F cathode material demonstrated a reversible activity of the Fe{sup 3+}/Fe{sup 2+} redox couple at the electrode potential near 3.4 V and minor activity of the Co{sup 3+}/Co{sup 2+} redox couple over 5 V vs Li/Li{sup +}. The material exhibited the discharge capacity of more than 82% (theo.) regarding Fe{sup 3+}/Fe{sup 2+} in the 2.4÷4.6 V vs Li/Li{sup +} potential range. - Graphical abstract: The ball-polyhedral representation of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F crystal structure. The MO{sub 4}F{sub 2} units are depicted as blue octahedra, PO{sub 4} units as orange tetrahedra, sodium atoms are designated as yellow (Na1), lithium – red and brown (Li2, Li3 resp.), fluorine – green, oxygen – violet spheres. - Highlights: • Freeze-drying method was successfully applied to the synthesis of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F. • The crystal structure of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F was refined based on NPD and validated by ED and HRTEM. • LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F demonstrated a reversible Li de/intercalation in the 2.5÷4.6 V vs Li/Li{sup +} range.

  14. Structural Transformations in High-Capacity Li 2 Cu 0.5 Ni 0.5 O 2 Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Ruther, Rose; Pandian, Amaresh S.; Yan, Pengfei; Weker, Johanna N.; Wang, Chongmin; Nanda, Jagjit

    2017-03-21

    Cathode materials that can cycle > 1 Li+ per transition metal are of substantial interest to increase the overall energy density of lithium-ion batteries. Li2Cu0.5Ni0.5O2 has a very high theoretical capacity of ~ 500 mAh/g assuming both Li+ are cycled reversibly. The Cu2+/3+ and Ni2+/3+/4+ redox couples are also at high voltage, which could further boost the energy density of this system. Despite such promise, Li2Cu0.5Ni0.5O2 undergoes irreversible phase changes during charge (delithiation) that result in large first-cycle irreversible loss and poor long-term cycling stability. Oxygen is evolved before the Cu2+/3+ or Ni3+/4+ transitions are accessed. In this contribution, XRD, TEM, and TXM-XANES are used to follow the chemical and structural changes that occur in Li2Cu0.5Ni0.5O2 during electrochemical cycling. Li2Cu0.5Ni0.5O2 is a solid solution of orthorhombic Li2CuO2 and Li2NiO2, but the structural changes more closely mimic the Li2NiO2 endmember. Li2Cu0.5Ni0.5O2 loses long-range order during charge, but TEM analysis provides clear evidence for particle exfoliation and the transformation from orthorhombic to a partially layered structure. Linear combination fitting and principal component analysis of TXM-XANES are used to map the different phases that emerge during cycling ex situ and in situ. Significant changes in the XANES at the Cu and Ni K-edges correlate with the onset of oxygen evolution.

  15. Synthesis of homogeneous Ca0.5Sr0.5FeO2.5+δ compound using a mirror furnace method

    International Nuclear Information System (INIS)

    Mahboub, M.S.; Zeroual, S.; Boudjada, A.

    2012-01-01

    Graphical abstract: X-ray diffraction pattern indexing of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample obtained by mirror furnace method after thermal treatment. Highlights: ► A homogenous compound Ca 0.5 Sr 0.5 FeO 2.5+δ has been synthesized for the first time by a mirror furnace method. ► Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample is perfectly homogenous, confirmed by X-ray diffraction, Raman spectroscopy and EDS technique. ► The thermal treatment of Ca 0.5 Sr 0.5 FeO 2.5+δ powder sample can increase their average grain sizes. -- Abstract: A new synthesis method using melting zone technique via the double mirror furnace around 1600 °C is used to obtain homogenous brownmillerite compounds Ca 1−x Sr x FeO 2.5+δ in the range 0.3 ≤ x ≤ 0.7. These compounds play important role in understanding the mystery of the oxygen diffusion in the perovskite-related oxides. We have successfully solved the miscibility gap problem by synthesizing a good quality of homogenous powder samples of Ca 0.5 Sr 0.5 FeO 2.5+δ compound. Our result was confirmed by X-rays diffraction, Raman spectroscopy and energy dispersive spectroscopy analysis. Thermal treatment was also applied until 800 °C under vacuum to confirm again the homogeneity of powder samples, improve its quality and show that no decomposition or return to form Ca- and Sr-enriched microdomains takes place as a result of phase separation.

  16. Magnetism and infrared magnetotransmission of Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} manganite in nanostate

    Energy Technology Data Exchange (ETDEWEB)

    Loshkareva, N.N., E-mail: loshkareva@imp.uran.ru; Mostovshchikova, E.V.; Korolyov, A.V.; Naumov, S.V.; Gizhevskii, B.A.; Solin, N.I.; Naumova, L.I.; Telegin, S.V.; Elokhina, L.V.

    2013-09-15

    The magnetic properties of nanopowders of Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} manganite, obtained by ball milling method, and IR magnetotransmission (the relative change in transmission of infrared radiation in a magnetic field) of composites based on the nanopowders are studied and compared with properties of Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} single crystal and coarse grain powder. The strong decrease of the magnetization at transformation of the single crystal to coarse grain powder is associated with the martensitic nature of the charge-ordered state (CO), T{sub CO}∼150 K. With a further decrease of particles size the magnetization decreases sharply above 150 K and is less significant in the region below 150 K, where a plateau in temperature dependence of magnetization and magnetotransmission takes place. The plateau is explained by modification of the manganite properties at milling and associated with competition of the ferromagnetic and antiferromagnetic contributions in cores and surface of the nanoparticles and change in the degree of localization of charge carriers in the magnetic field. The high value of the magnetotransmission (up to 9%) in a wide temperature range for nanocomposites are promising for creation of magnetically controlled infrared optoelectronic devices. - Highlights: • Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} nanopowders were obtained by the ball-milling method. • Difference in the magnetic properties of nanopowders and bulk crystals was revealed. • High value of IR magnetotransmition of Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} nanocomposites was found. • Relationship between magnetism and magnetotransmition of nano-Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} is shown.

  17. Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6-12 Years of Age in Mexico.

    Science.gov (United States)

    Bashash, Morteza; Thomas, Deena; Hu, Howard; Martinez-Mier, E Angeles; Sanchez, Brisa N; Basu, Niladri; Peterson, Karen E; Ettinger, Adrienne S; Wright, Robert; Zhang, Zhenzhen; Liu, Yun; Schnaas, Lourdes; Mercado-García, Adriana; Téllez-Rojo, Martha María; Hernández-Avila, Mauricio

    2017-09-19

    Some evidence suggests that fluoride may be neurotoxic to children. Few of the epidemiologic studies have been longitudinal, had individual measures of fluoride exposure, addressed the impact of prenatal exposures or involved more than 100 participants. Our aim was to estimate the association of prenatal exposure to fluoride with offspring neurocognitive development. We studied participants from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project. An ion-selective electrode technique was used to measure fluoride in archived urine samples taken from mothers during pregnancy and from their children when 6-12 y old, adjusted for urinary creatinine and specific gravity, respectively. Child intelligence was measured by the General Cognitive Index (GCI) of the McCarthy Scales of Children's Abilities at age 4 and full scale intelligence quotient (IQ) from the Wechsler Abbreviated Scale of Intelligence (WASI) at age 6-12. We had complete data on 299 mother-child pairs, of whom 287 and 211 had data for the GCI and IQ analyses, respectively. Mean (SD) values for urinary fluoride in all of the mothers (n=299) and children with available urine samples (n=211) were 0.90 (0.35) mg/L and 0.82 (0.38) mg/L, respectively. In multivariate models we found that an increase in maternal urine fluoride of 0.5mg/L (approximately the IQR) predicted 3.15 (95% CI: -5.42, -0.87) and 2.50 (95% CI -4.12, -0.59) lower offspring GCI and IQ scores, respectively. In this study, higher prenatal fluoride exposure, in the general range of exposures reported for other general population samples of pregnant women and nonpregnant adults, was associated with lower scores on tests of cognitive function in the offspring at age 4 and 6-12 y. https://doi.org/10.1289/EHP655.

  18. X-ray photoelectron spectroscopic study of direct reforming catalysts Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Keunsoo [Department of Engine Research, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon 305-343 (Korea, Republic of); Jeong, Jihoon [Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Azad, Abul K. [Faculty of Integrated Technologies, University Brunei Darussalam, Jalan Tunku Link, Gadong BE1410 (Brunei Darussalam); Jin, Sang Beom [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of); Kim, Jung Hyun, E-mail: jhkim2011@hanbat.ac.kr [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of)

    2016-03-01

    Graphical abstract: Measured Ti 2p peaks and deconvolution peaks of Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} under oxidizing condition (left) and NSTM under reducing condition (right). - Highlights: • Chemical states of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) were analyzed. • Charge compensation occurred with the reduction of Mn and Ti. • The Nd substitution effect allowed some Ti to convert into a metallic behavioral component. • NSTM and SSTM had a large amount of lattice oxygen; however, LSTM retained a large quantity of adsorbed oxygen. - Abstract: Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O

  19. Structure and optical band-gap energies of Ba0.5Sr0.5TiO3 thin films fabricated by RF magnetron plasma sputtering

    International Nuclear Information System (INIS)

    Xu, Zhimou; Suzuki, Masato; Yokoyama, Shin

    2005-01-01

    The structure and optical band-gap energies of Ba 0.5 Sr 0.5 TiO 3 (BST0.5) thin films prepared on SiO 2 /Si and fused quartz substrates by RF magnetron plasma sputtering were studied in terms of deposition temperature and film thickness. Highly (100)-oriented BST0.5 thin films were successfully sputtered on a Si substrate with an approximately 1.0-μm-thick SiO 2 layer at a deposition temperature of above 450degC. The optical transmittance of BST0.5 thin films weakly depended on the magnitude of X-ray diffraction (XRD) peak intensity. This is very helpful for monolithic integration of BST0.5 films for electrooptical functions directly onto a SiO 2 /Si substrate. The band-gap energies showed a strong dependence on the deposition temperature and film thickness. It was mainly related to the quantum size effect and the influence of the crystallinity of thin films, such as grain boundaries, grain size, oriented growth, and the existence of an amorphous phase. The band-gap energy values, which were much larger than those of single crystals, decreased with the increase in the deposition temperature and the thickness of BST0.5 thin films. The band-gap energy of 311-nm-thick amorphous BST0.5 thin film was about 4.45 eV and that of (100)-oriented BST0.5 thin film with a thickness of 447 nm was about 3.89 eV. It is believed that the dependence of the band-gap energies of the thin films on the crystallinity for various values of deposition temperature and film thickness means that there could be application in integrated optical devices. (author)

  20. A mixed iron-manganese based pyrophosphate cathode, Na2Fe0.5Mn0.5P2O7, for rechargeable sodium ion batteries.

    Science.gov (United States)

    Shakoor, Rana A; Park, Chan Sun; Raja, Arsalan A; Shin, Jaeho; Kahraman, Ramazan

    2016-02-07

    The development of secondary batteries based on abundant and cheap elements is vital. Among various alternatives to conventional lithium-ion batteries, sodium-ion batteries (SIBs) are promising due to the abundant resources and low cost of sodium. While there are many challenges associated with the SIB system, cathode is an important factor in determining the electrochemical performance of this battery system. Accordingly, ongoing research in the field of SIBs is inclined towards the development of safe, cost effective cathode materials having improved performance. In particular, pyrophosphate cathodes have recently demonstrated decent electrochemical performance and thermal stability. Herein, we report the synthesis, electrochemical properties, and thermal behavior of a novel Na2Fe0.5Mn0.5P2O7 cathode for SIBs. The material was synthesized through a solid state process. The structural analysis reveals that the mixed substitution of manganese and iron has resulted in a triclinic crystal structure (P1[combining macron] space group). Galvanostatic charge/discharge measurements indicate that Na2Fe0.5Mn0.5P2O7 is electrochemically active with a reversible capacity of ∼80 mA h g(-1) at a C/20 rate with an average redox potential of 3.2 V. (vs. Na/Na(+)). It is noticed that 84% of initial capacity is preserved over 90 cycles showing promising cyclability. It is also noticed that the rate capability of Na2Fe0.5Mn0.5P2O7 is better than Na2MnP2O7. Ex situ and CV analyses indicate that Na2Fe0.5Mn0.5P2O7 undergoes a single phase reaction rather than a biphasic reaction due to different Na coordination environment and different Na site occupancy when compared to other pyrophosphate materials (Na2FeP2O7 and Na2MnP2O7). Thermogravimetric analysis (25-550 °C) confirms good thermal stability of Na2Fe0.5Mn0.5P2O7 with only 2% weight loss. Owing to promising electrochemical properties and decent thermal stability, Na2Fe0.5Mn0.5P2O7, can be an attractive cathode for SIBs.

  1. Terahertz conductivity measurement of FeSe0.5Te0.5 and Co-doped BaFe2As2 thin films

    International Nuclear Information System (INIS)

    Nakamura, D.; Akiike, T.; Takahashi, H.; Nabeshima, F.; Imai, Y.; Maeda, A.; Katase, T.; Hiramatsu, H.; Hosono, H.; Komiya, S.; Tsukada, I.

    2011-01-01

    We investigated the THz conductivity of FeSe 0.5 Te 0.5 and Ba (Fe 2-x Co x )As 2 thin films. We estimated the superconducting gap energy values. We found anomolous conductivity spectrum in the antiferromagnetic phase. The terahertz (THz) conductivity of FeSe 0.5 Te 0.5 ('11'-type) and Co-doped BaFe 2 As 2 ('122'-type) thin films are investigated. For '11'-type, the frequency dependence of the complex conductivity can be understood as that of BCS-type superconductor near the superconducting gap energy, and we estimated the superconducting gap energy to be 0.6 meV. For '122'-type, we estimated the superconducting gap energy to be 2.8 meV, which is considered to be the superconducting gap opened at the electron-type Fermi surface near the M point.

  2. Thermochromic effect at room temperature of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Boileau, A.; Capon, F.; Barrat, S.; Pierson, J. F. [Universite de Lorraine, Institut Jean Lamour, Departement CP2S, UMR CNRS 7198, Nancy, F-54042 (France); Laffez, P. [Groupe de Recherche Electronique, Materiaux, Acoustique, Nanoscience (GREMAN), Universite Francois Rabelais de Tours, UMR CNRS 7347, IUT de Blois, 15 rue de la Chocolaterie, Blois, F-41000 (France)

    2012-06-01

    Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thermochromic thin films were synthesized using dc reactive magnetron co-sputtering and subsequent annealing in air. The film structure was studied by x-ray diffraction analysis. To validate the thermochromic potentiality of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3}, electrical resistivity and infrared transmittance spectra were recorded for temperatures ranging from 77 K to 420 K. The temperature dependence of the optical band gap was estimated in the near infrared range. Upon heating, the optical transmission decreases in the infrared domain showing a thermochromic effect over a wide wavelength range at room temperature.

  3. Quantum dots of Cd0.5Mn0.5Te semimagnetic semiconductor formed by the cold isostatic pressure method

    International Nuclear Information System (INIS)

    Contreras, O.; Power, Ch.; Quintero, M.; Morocoima, M.; Tovar, R.; Quintero, E.; Gonzalez, J.; Munoz-San Jose, V.; Broto, J.M.; Snoeck, E.

    2005-01-01

    Cd 0.5 Mn 0.5 Te is a semimagnetic semiconductor, which crystallizes in the zinc-blende structure (ZB) and exhibits a magnetic spin glass like transition at 21 K. Under pressure it shows a first-order phase transition around 2.6 GPa to the NaCl like structure. In this work, the pressure cycled method using a Paris-Edinburgh cell up to 8 GPa has been applied to Cd 0.5 Mn 0.5 Te samples in order to obtain recovered nanocrystals. The nanoparticles have been characterized by EDX and electron microscopy. The X-ray and electron diffraction results confirmed the existence of nanocrystals in the ZB phase with an average size of 7 nm. Magnetization measurements made in the range of 2-300 K at low field show that the temperature of the magnetic transition decreases when the crystallites' size is reduced

  4. Influence of heat treatment on the mechanical and electrical characteristics of Ni0.5Ti0.5 alloy prepared by electron-beam melting

    International Nuclear Information System (INIS)

    Ammar, A.H.; Al-Buhairi, M.; Farag, A.A.M.; Al-Wajeeh, N.M.M.

    2013-01-01

    Nickel titanium alloys (Ni 0.5 Ti 0.5 ) were successfully produced from elemental Ni/Ti powders by electron-beam melting method and then subjected to annealing and aging treatment. Microstructure of the alloys was examined by XRD and SEM. The mechanical properties of the alloyed surface were examined. The microhardness was studied as a function of annealing temperature and time. It was found that the microhardness decreases with increasing annealing temperature until 660 °C after which the microhardness increases. Electrical resistance measurements were carried out in order to study the transformation behavior. The electrical measurements point out the importance of temperature dependence of Ni 0.5 Ti 0.5 electrical resistance for the identification of particular transformation. The influence of aging on the development of electrical resistivity was also investigated

  5. Manipulating multiple order parameters via oxygen vacancies: The case of E u0.5B a0.5Ti O3 -δ

    Science.gov (United States)

    Li, Weiwei; He, Qian; Wang, Le; Zeng, Huizhong; Bowlan, John; Ling, Langsheng; Yarotski, Dmitry A.; Zhang, Wenrui; Zhao, Run; Dai, Jiahong; Gu, Junxing; Shen, Shipeng; Guo, Haizhong; Pi, Li; Wang, Haiyan; Wang, Yongqiang; Velasco-Davalos, Ivan A.; Wu, Yangjiang; Hu, Zhijun; Chen, Bin; Li, Run-Wei; Sun, Young; Jin, Kuijuan; Zhang, Yuheng; Chen, Hou-Tong; Ju, Sheng; Ruediger, Andreas; Shi, Daning; Borisevich, Albina Y.; Yang, Hao

    2017-09-01

    Controlling functionalities, such as magnetism or ferroelectricity, by means of oxygen vacancies (VO) is a key issue for the future development of transition-metal oxides. Progress in this field is currently addressed through VO variations and their impact on mainly one order parameter. Here we reveal a mechanism for tuning both magnetism and ferroelectricity simultaneously by using VO. Combining experimental and density-functional theory studies of E u0.5B a0.5Ti O3 -δ , we demonstrate that oxygen vacancies create T i3 +3 d1 defect states, mediating the ferromagnetic coupling between the localized Eu 4 f7 spins, and increase an off-center displacement of Ti ions, enhancing the ferroelectric Curie temperature. The dual function of Ti sites also promises a magnetoelectric coupling in the E u0.5B a0.5Ti O3 -δ .

  6. Global and local structural variations near the antiferroelectric regime in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Thangavelu, Karthik [Advanced Functional Materials Laboratory, Department of Physics, Indian Institute of Technology Hyderabad, ODF-Campus-502205 (India); Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, ODF-Campus-502205 (India); Rayaprol, S. [UGC-DAE CSR Mumbai Centre, BARC Campus, Mumbai - 400085 (India); Siruguri, V. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085 (India); Sastry, P. U.; Asthana, Saket, E-mail: asthanas@iith.ac.in

    2015-06-24

    Rietveld refinement of neutron and x-ray diffraction data of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} shows R3c phase stabilization at room temperature. The intermediate antiferroelectric region between 180°C to 280°C exhibits phase coexistence i.e R3c + Pnma, along with decrease in octahedral tilt angle and increase in unit cell volume. The local structural changes observed from Raman scattering in the A-O, Ti-O and TiO{sub 6} phonon modes favor the global structural variation. A possible antiparallel cation displacement due to Pnma phase formation leads to the origin of antiferroelectric ordering in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}.

  7. The role of structural order-disorder for visible intense photoluminescence in the BaZr0.5Ti0.5O3 thin films

    International Nuclear Information System (INIS)

    Anicete-Santos, M.; Cavalcante, L.S.; Orhan, E.; Paris, E.C.; Simoes, L.G.P.; Joya, M.R.; Rosa, I.L.V.; Lucena, P.R. de; Santos, M.R.M.C.; Santos-Junior, L.S.; Pizani, P.S.; Leite, E.R.; Varela, J.A.; Longo, E.

    2005-01-01

    The nature of the intense visible room temperature photoluminescence of BaZr 0.5 Ti 0.5 O 3 non-crystalline thin films is discussed in the light of experimental results and theoretical calculations. The photoluminescence measurements reveal that the emission intensity changes with the degree of disorder in the BaZr 0.5 Ti 0.5 O 3 lattice. First principles quantum mechanical techniques, based on density functional theory at B3LYP level, have been employed to study the electronic structure of a crystalline model and of structurally disordered models in order to detect the influence of disorder on the electronic structure. An analysis of the electronic charge distribution reveals local polarization in the disordered structures. The relevance of the present theoretical and experimental results on the photoluminescence behavior of BZT is discussed

  8. Fabrication of highly spin-polarized Co2FeAl0.5Si0.5 thin-films

    Directory of Open Access Journals (Sweden)

    M. Vahidi

    2014-04-01

    Full Text Available Ferromagnetic Heusler Co2FeAl0.5Si0.5 epitaxial thin-films have been fabricated in the L21 structure with saturation magnetizations over 1200 emu/cm3. Andreev reflection measurements show that the spin polarization is as high as 80% in samples sputtered on unheated MgO (100 substrates and annealed at high temperatures. However, the spin polarization is considerably smaller in samples deposited on heated substrates.

  9. Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3-δ

    NARCIS (Netherlands)

    Berenov, A.; Atkinson, A.; Kilner, J.; Ananyev, M.; Eremin, V.; Porotnikova, N.; Farlenkov, A.; Kurumchin, E.; Bouwmeester, Henricus J.M.; Bucher, E.; Sitte, W.

    2014-01-01

    The oxygen tracer diffusion coefficient, Db⁎, and the oxygen tracer surface exchange coefficient, k, were measured in Ba0.5Sr0.5Co0.8Fe0.2O3 − δ (BSCF5582) over the temperature range of 310–800 °C and the oxygen partial pressure range of 1.3 × 10−3–0.21 bar. Several measurement techniques were used:

  10. Photoemission spectroscopy of the charge-ordering transition in Pr0.5Sr0.5MnO3

    International Nuclear Information System (INIS)

    Chainani, A.; Kumigashira, H.; Takahashi, T.; Tomioka, Y.; Kuwahara, H.; Tokura, Y.

    1996-01-01

    In this paper, the electronic structure of the magnetite Pr 0.5 Sr 0.5 MnO 3 across the charge ordering transition is studied using temperature-dependent photoemission spectroscopy. Ultra-violet photoemission spectroscopy have been performed as a function of temperature (25-300K) to investigate the changes in the single-particle density of states across the metal-nonmetal and the para-ferro transitions

  11. Luminescent characteristics of UV excited Sr_0_._5Ca_0_._5TiO_3: Pr"3"+ reddish-orange phosphor

    International Nuclear Information System (INIS)

    Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R.

    2016-01-01

    Pr"3"+ doped Sr_0_._5Ca_0_._5TiO_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_0_._5Ca_0_._5TiO_3: x Pr"3"+ phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr_0_._5Ca_0_._5TiO_3: x Pr"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"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_0_._5Ca_0_._5TiO_3: x Pr"3"+ perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from "3P_J levels of Pr"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.

  12. (1−x)[(K$_{0.5}$Na$_{0.5}$)NbO$_3$–LiSbO$_3

    Indian Academy of Sciences (India)

    Lead-free piezoelectric ceramics ( 1 − x ) [0.95(K 0.5 Na 0.5 )NbO 3 –0.05LiSbO 3 ]– x BiFe 0.8 Co 0.2 O 3 (KNN–LS– x BFC) were prepared by a conventional sintering technique. The effect of BFC content on the structure, piezoelectricand electrical properties of KNN–LS ceramics was investigated. The results reveal that ...

  13. Effect of oxygen stoichiometry on the electrical properties of La0.5Sr0.5CoO3 electrodes

    International Nuclear Information System (INIS)

    Madhukar, S.; Aggarwal, S.; Dhote, A.M.; Ramesh, R.; Krishnan, A.; Keeble, D.; Poindexter, E.

    1997-01-01

    We report on the metal-insulator transition of La 0.5 Sr 0.5 CoO 3 thin films deposited by pulsed laser ablation on LaAlO 3 substrates. The films were cooled in oxygen partial pressures between 760 and 10 -5 Torr and electrical resistivity of the films was measured as a function of cooling oxygen pressure. La 0.5 Sr 0.5 CoO 3 films changed from metallic to insulating behavior depending on their oxygen content. A defect model has been proposed to explain this transition and the change in conductivity is related to the change in the oxidation state of the cobalt ions. The model explains the relationship between oxygen partial pressure and electrical conductivity in La 0.5 Sr 0.5 CoO 3 , which describes the experimental dependence reasonably well. Positron annihilation studies were also done on the same set of samples and the S parameter was seen to increase by 8% from a fully oxygenated sample to a sample cooled in 10 -5 Torr. copyright 1997 American Institute of Physics

  14. Synthesis and Characterization of Nano-Crystalline Cu and Pb0.5-Cu0.5- ferrites by Mechanochemical Method and Their Electrical and Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    V. B. GAIKWAD

    2011-11-01

    Full Text Available In the present communication, we have reported the synthesis of nanocrystalline ferrites of the type CuFe2O4 and Pb0.5Cu0.5Fe2O4 by mechanochemical alloying at 960 0C. The samples prepared were characterized by X-ray diffraction (XRD, VSM, FT-IR, UV-DRS, and SEM. The average particle size was determined by XRD pattern using Scherrer equation and it is 7.295 nm, 4.484 nm for CuFe2O4, and Pb0.5Cu0.5Fe2O4. The surface morphology of the samples is characterized by scanning electron microscopy (SEM. Magnetic studies were carried out using vibrating sample magnetometer (VSM and shows very high coercive field for the mixed ferrite. UV-DRS studies were performed to investigate the band gap of synthesized nanocrystalline material. Electrical properties show semiconducting nature of synthesized ferrites. The thick films of the material were prepared by screen printing method. The gas sensing properties were studied towards reducing gases like CO, NH3 and H2S and it was revealed that CuFe2O4 is the most sensitive and selective to H2S gas at relatively lower operating temperature 200 0C. Furthermore Pb0.5Cu0.5Fe2O4 also shows the response to H2S at operating temperature 300 0C.

  15. Influence of substrate type on transport properties of superconducting FeSe0.5Te0.5 thin films

    International Nuclear Information System (INIS)

    Yuan, Feifei; Shi, Zhixiang; Iida, Kazumasa; Langer, Marco; Hänisch, Jens; Hühne, Ruben; Schultz, Ludwig; Ichinose, Ataru; Tsukada, Ichiro; Sala, Alberto; Putti, Marina

    2015-01-01

    FeSe 0.5 Te 0.5 thin films were grown by pulsed laser deposition on CaF 2 , LaAlO 3 and MgO substrates and structurally and electro-magnetically characterized in order to study the influence of the substrate on their transport properties. The in-plane lattice mismatch between FeSe 0.5 Te 0.5 bulk and the substrate shows no influence on the lattice parameters of the films, whereas the type of substrate affects the crystalline quality of the films and, therefore, the superconducting properties. The film on MgO showed an extra peak in the angular dependence of critical current density J c (θ) at θ = 180° (H||c), which arises from c-axis defects as confirmed by transmission electron microscopy. In contrast, no J c (θ) peaks for H||c were observed in films on CaF 2 and LaAlO 3 . J c (θ) can be scaled successfully for both films without c-axis correlated defects by the anisotropic Ginzburg–Landau approach with appropriate anisotropy ratio γ J . The scaling parameter γ J is decreasing with decreasing temperature, which is different from what we observed in FeSe 0.5 Te 0.5 films on Fe-buffered MgO substrates. (paper)

  16. Grain boundary defect compensation in Ti-doped BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiaojun; Deng, Jianming; Liu, Saisai; Yan, Tianxiang; Fang, Liang; Liu, Laijun [Guilin University of Technology, Key Laboratory of Nonferrous Materials and New Processing Technology, Ministry of Education, College of Materials Science and Engineering, Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices, Guilin (China); Peng, Biaolin [Guangxi University, School of Physical Science and Technology and Guangxi Key Laboratory for Relativistic Astrophysics, Nanning (China); Jia, Wenhao [Shanghai Getong Enterprise Co., Ltd., Shanghai (China); Mei, Zaoming [Henan LiHeng Building Materials Co., Ltd., Zhengzhou (China); Su, Hongbo [Henan Province Product Quality Supervision and Inspection Center, Zhengzhou (China)

    2016-09-15

    Giant dielectric ceramics Ba(Nb{sub 0.5}Fe{sub 0.5-x}Ti{sub x})O{sub 3} (BNFT) have been fabricated by a conventional solid-state reaction. According to X-ray diffraction analysis, the crystal structure of these ceramics can be described by the cubic centrosymmetric with Pm-3m space group. The real part (ε') of dielectric permittivity and dielectric loss (tan δ) of the BNFT ceramics was measured in a frequency range from 40 Hz to 100 MHz at room temperature. The (ε') of all these samples displays a high value (∝6500) and a small frequency-dependence from 1 kHz to 1 MHz. We have established a link between conductivity activation energy and defect compensation at grain boundaries. The Ti{sup 4+}-doped Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} as a donor makes a great influence on the grain boundary behavior, which restricts the migration of oxygen vacancy and depresses dielectric loss factor for Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} ceramics. (orig.)

  17. Loading Cd0.5Zn0.5S Quantum Dots onto Onion-Like Carbon Nanoparticles to Boost Photocatalytic Hydrogen Generation.

    Science.gov (United States)

    Zhou, Xiaolong; Wang, Xina; Feng, Xi; Zhang, Kun; Peng, Xiaoniu; Wang, Hanbin; Liu, Chunlei; Han, Yibo; Wang, Hao; Li, Quan

    2017-07-12

    Carbon dots (C dots, size < 10 nm) have been conventionally decorated onto semiconductor matrixes for photocatalytic H 2 evolution, but the efficiency is largely limited by the low loading ratio of the C dots on the photocatalyst. Here, we propose an inverse structure of Cd 0.5 Zn 0.5 S quantum dots (QDs) loaded onto the onionlike carbon (OLC) matrix for noble metal-free photocatalytic H 2 evolution. Cd 0.5 Zn 0.5 S QDs (6.9 nm) were uniformly distributed on an OLC (30 nm) matrix with both upconverted and downconverted photoluminescence property. Such an inverse structure allows the full optimization of the QD/OLC interfaces for effective energy transfer and charge separation, both of which contribute to efficient H 2 generation. An optimized H 2 generation rate of 2018 μmol/h/g (under the irradiation of visible light) and 58.6 μmol/h/g (under the irradiation of 550-900 nm light) was achieved in the Cd 0.5 Zn 0.5 S/OLC composite samples. The present work shows that using the OLC matrix in such a reverse construction is a promising strategy for noble metal-free solar hydrogen production.

  18. Observation of magnetization and exchange bias reversals in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sharannia, M.P.; De, Santanu [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Singh, Ripandeep; Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Nirmala, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Santhosh, P.N., E-mail: santhosh@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2017-05-15

    Polycrystalline NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} has orthorhombic structure with Pnma space group and is magnetically ordered at room temperature as confirmed by neutron diffraction. The magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} shows magnetization reversal and sign reversal of exchange bias at ~16 K. Nd{sup 3+} moments that get induced by the internal field of |Fe+Cr| sublattice couple antiferromagnetically with the ferromagnetic component of |Fe+Cr| sublattice. Nd{sup 3+} moments overcome the |Fe+Cr| moments at ~16 K below which the material shows negative magnetization and positive exchange bias. - Highlights: • Neutron diffraction confirms magnetic ordering at 300 K in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}. • Magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. • Nd{sup 3+} moments couple antiferromagnetically with |Fe+Cr| ferromagnetic moments. • Shows magnetization reversal and exchange bias reversal.

  19. Enhanced Photocatalytic Hydrogen Evolution by Loading Cd0.5Zn0.5S QDs onto Ni2P Porous Nanosheets

    Science.gov (United States)

    Xiao, Lingfeng; Su, Tong; Wang, Zhuo; Zhang, Kun; Peng, Xiaoniu; Han, Yibo; Li, Quan; Wang, Xina

    2018-02-01

    Ni2P has been decorated on CdS nanowires or nanorods for efficient photocatalytic H2 production, whereas the specific surface area remains limited because of the large size. Here, the composites of Cd0.5Zn0.5S quantum dots (QDs) on thin Ni2P porous nanosheets with high specific surface area were constructed for noble metal-free photocatalytic H2 generation. The porous Ni2P nanosheets, which were formed by the interconnection of 15-30 nm-sized Ni2P nanoparticles, allowed the uniform loading of 7 nm-sized Cd0.5Zn0.5S QDs and the loading density being controllable. By tuning the content of Ni2P, H2 generation rates of 43.3 μM h- 1 (1 mg photocatalyst) and 700 μM h- 1 (100 mg photocatalyst) and a solar to hydrogen efficiency of 1.5% were achieved for the Ni2P-Cd0.5Zn0.5S composites. The effect of Ni2P content on the light absorption, photoluminescence, and electrochemical property of the composite was systematically studied. Together with the band structure calculation based on density functional theory, the promotion of Ni2P in charge transfer and HER activity together with the shading effect on light absorption were revealed. Such a strategy can be applied to other photocatalysts toward efficient solar hydrogen generation.

  20. Combustion synthesis and characterization of MV0.5P0.5O4: Sm3+, Tm3+ (M = Gd, La, Y)

    Science.gov (United States)

    Motloung, Selepe J.; Lephoto, Mantwa A.; Tshabalala, Kamohelo G.; Ntwaeaborwa, Odireleng M.

    2018-04-01

    In this paper, GdV0.5P0.5O4: Sm3+, Tm3+, LaV0.5P0.5O4: Sm3+, Tm3+ and YV0.5P0.5O4: Sm3+, Tm3+ phosphor powders were prepared by solution combustion method using urea as a fuel. The phase purity, surface morphology, optical and photoluminescence properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence spectroscopy. The XRD results indicated that the prepared powders are of a single phase and crystallized in tetragonal structure for Gd and Y systems while monoclinic phase was observed for La system. SEM showed that the samples consisted of mixed structures. The estimated band gaps were 2.2, 2.4 and 2.3 eV for Y, Gd and La systems respectively. The photoluminescence results showed four emission peaks. One peak is assigned to 1G4 - 3H6 transition of Tm3+, and three other emission peaks are attributed to 6G5/2 - 6H5/2, 6G5/2 - 6H7/2 and 6G5/2 - 6H9/2 transitions of Sm3+. The photoluminescent intensity was the highest in the gadolinium system.

  1. Oxygen vacancies induced enhancement of photoconductivity of La0.5Sr0.5CoO3 - δ thin film

    Science.gov (United States)

    Gao, R. L.; Fu, C. L.; Cai, W.; Chen, G.; Deng, X. L.; Yang, H. W.; Sun, J. R.; Zhao, Y. G.; Shen, B. G.

    2014-09-01

    Effects of light and electrical current on the electrical transport properties and photovoltaic properties of oxygen-stoichiometric La0.5Sr0.5CoO3 and oxygen-deficient La0.5Sr0.5CoO3 - δ films prepared by pulsed laser deposition have been investigated. Oxygen-deficient films annealed in a vacuum show an obvious increase of resistance and lattice parameter. Besides, a direct correlation between the magnitude of the photoconductivity and oxygen vacancies in La0.5Sr0.5CoO3 - δ films has been observed. The light illumination causes a resistance drop to show the photoconductivity effect. Moreover, the photoconductivity can be remarkably enhanced by increasing the electrical current, that is, it exhibits current-enhanced photoconductivity (CEPC) effect. Oxygen deficiency in the annealed film leads to the formation of a structural disorder in the Co-O-Co conduction channel due to the accumulated oxygen vacancies and hence is believed to be responsible for the increase in higher photoconductivity. These results may be important for practical applications in photoelectric devices.

  2. Quarternair CuGaSeTe and CuGa0.5In 0.5Te2 Thin Films Fabrication Using Flash Evaporation

    Directory of Open Access Journals (Sweden)

    A Harsono Soepardjo

    2010-10-01

    Full Text Available Quarternair materials CuGaSeTe and CuGa0.5In 0.5Te2 are the basic materials to solar cell fabrication. These materials have high absorption coefficients around 103 - 105 cm-1 and band gap energy in the range of 1-5 eV. In this research, the films were made by flash evaporation method using quarternair powder materials of CuGaSeTe and CuGa0.5In 0.5Te2 to adhere in a glass substrate. After the films were obtained, the properties of these films will be characterized optically and electrically. The lattice parameter of the films and the crystalline film structure were obtained using X-Ray Diffraction (XRD spectroscopy. The XRD results show that the quarternair CuGaSeTe and CuGa0.5In 0.5Te2 films have a chalcopyrite structure. The absorption coefficient and the  band gap energy of the films were calculated using transmittance and reflectance patterns that measured using UV-VIS Difractometer. The films composition can be detected by using the Energy Dispersive Spectroscopy (EDS, while the films resistivity, mobility and the majority carrier of the films were obtained from Hall Effect experiments.

  3. Perpendicular magnetic anisotropy in Co2FeAl0.5Si0.5/MgO bottom electrodes for magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Li, X.Q.; Wu, Y.; Gao, S.; Xu, X.G.; Miao, J.; Jiang, Y.

    2013-01-01

    Perpendicular magnetic anisotropy (PMA) was achieved in annealed Co 2 FeAl 0.5 Si 0.5 (CFAS)/MgO-based multilayers with good thermal stability up to 400 °C and a large anisotropy energy density K u over 2.0 × 10 5 J/m 3 . The thickness of the full-Heusler CFAS film to maintain PMA is up to 4.8 nm in which the co-existence of disordered A2, ordered B2 and fully ordered L2 1 structures is observed. X-ray photoelectron spectroscopy analysis demonstrates that the origin of the PMA is the hybridization between Co 3d and O 2p orbitals at the CFAS/MgO interface. - Highlights: • We achieved perpendicular magnetic anisotropy (PMA) in Co 2 FeAl 0.5 Si 0.5 (4.8 nm) film; • L2 1 , B2 and A2 phases coexist in perpendicular magnetic anisotropic Co 2 FeAl 0.5 Si 0.5 ; • Magnetic properties have strong dependence on the annealing temperature; • The PMA is induced by the hybridization between Co-3d and O-2p orbitals

  4. Preparation and Characterization of Pu0.5Am0.5O2-x-MgO Ceramic/Ceramic Composites

    International Nuclear Information System (INIS)

    Jankowiak, A.; Jorion, F.; Donnet, L.; Maillard, C.

    2008-01-01

    This study describes the preparation and characterization of Pu 0.5 Am 0.5 O 2-x -MgO ceramic/ceramic (cercer) composites with 20 and 30 vol% of Pu 0.5 Am 0.5 O 2-x . The sintered materials demonstrated very different reduction behavior when exposed to a reducing sintering cycle. The composites were studied by combined X-ray diffraction (XRD) and oxygen-to-metal ratio measurements and exhibited various amounts of body-centered-cubic (bcc) and face-centered-cubic (fcc) phases corresponding to different reduction states of the mixed actinide oxide. The fcc phases correspond to a near stoichiometry phase while the bcc phases are attributed to most reduced phases, which demonstrate a greater similarity with the Am 2 O 3 bcc phase. The XRD results suggest a reduction of Am prior to Pu, which explains this greater similarity. In addition, the 30 vol% composite contains 65 wt% of the bcc phase while the 20 vol% composite exhibits only 29 wt%. This result can be explained by the percolation theory when applied to the oxygen diffusivity and indicates that a threshold value for Pu 0.5 Am 0.5 O 2-x content in the cercer composite exists where the reduction of the mixed oxide significantly increases. (authors)

  5. FABRICATION AND MECHANICAL PROPERTIES OF Na0.5Bi0.5TiO3–BaTiO3 LEAD-FREE PIEZOELECTRIC CERAMICS

    Directory of Open Access Journals (Sweden)

    PAN YUSONG

    2014-03-01

    Full Text Available Piezoelectric ceramics with 0.94Na0.5Bi0.5TO3–0.06BaTiO3 compositions were fabricated by solid state mixed oxide method and sintered at different temperatures varying from 1050°C to 1150°C to obtain dense ceramics. Phase analysis using X-ray diffraction showed tetragonal perovskite structure of Na0.5Bi0.5TO3 with no BaTiO3 peak detected. The SEM observation revealed that the crystal grain size of the piezoelectric ceramics is on the nano-size dimensions under all the sintering temperature. The study on the compressive mechanical characteristics showed that the compressive strength of the 0.94Na0.5Bi0.5TO3–0.06BaTiO3 piezoelectric ceramics increases with the rise of sintering temperature and sintering time. The change behavior of the compressive strength with the rise of cold pressure presents increasing firstly and then decreases.

  6. Comparative study of optical and scintillation properties of YVO4, (Lu0.5Y0.5)VO4, and LuVO4 single crystals

    International Nuclear Information System (INIS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Chani, Valery; Kochurikhin, Vladimir V.; Yoshikawa, Akira

    2011-01-01

    Optical and scintillation properties of YVO 4 , (Lu 0.5 Y 0.5 )VO 4 , and LuVO 4 single crystals grown by the Czochralski (CZ) method with RF heating system are compared. All vanadate crystals show high transmittance (∼80%) in the 400-900 nm wavelength range. In both photo- and radio-luminescence spectra, intense peak around 400-500 nm, which was ascribed to the transition from triplet state of VO 4 3- , was clearly observed. The main decay time component was about 38 μs (YVO 4 ), 18 μs ((Lu 0.5 Y 0.5 )VO 4 ), and 17 μs (LuVO 4 ) under 340 nm excitation. The scintillation light yields of YVO 4 , (Lu 0.5 Y 0.5 )VO 4 , and LuVO 4 crystals (obtained from the 137 Cs excited pulse height spectra) were evaluated to be about 11,200, 10,700, and 10,300 ph/MeV, respectively.

  7. Emergence of Griffiths phase and glassy mixed phase in Sm0.5Ca0.5MnO3 nanomanganites

    International Nuclear Information System (INIS)

    Giri, S.K.; Yusuf, S.M.; Mukadam, M.D.; Nath, T.K.

    2014-01-01

    Graphical abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase, and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3 manganite are carried out. A rigorous measurement of linear and non-linear ac magnetic susceptibilities, time dependent relaxation and aging phenomena in Sm 0.5 Ca 0.5 MnO 3 nanomanganite confirm the existence of a glassy mixed phase in the low temperature regime. The signature of Griffiths phase in nanosized manganite has been confirmed from the detailed ac and dc magnetization studies. The existence of Griffiths phase is verified through the anomalous behavior of the low field temperature dependent an inverse ac and dc magnetic susceptibility. Based on experimental results, the glassy phase of nanomanganites has been attributed to the phase separation effect and interaction between the ferromagnetic clusters. A phenomenological core/shell model has also been proposed based on the surface disorder to explain the observed Griffiths phase in these nanosized manganites. Fig. 1: (Left) The plot of inverse of ac susceptibility χ ac -1 measured at f = 1 Hz and H ac = 2 Oe as a function of temperature for S750 sample. Inset shows the same for S550 sample. (Right) A schematic of the proposed model to describe the magnetic state of the Sm 0.5 Ca 0.5 MnO 3 system at different average sizes. Highlights: • Effect of grain size on Griffiths phase and glassy mixed phase is discussed. • GP is confirmed by dc, linear and non-linear ac magnetization in nanomanganites. • Glassy mixed phase is discussed by time dependent relaxation and aging phenomena. • The existence of GP is verified through an inverse ac and dc magnetic susceptibility. • A phenomenological core/shell model has been proposed based on surface disorder. -- Abstract: A detailed investigation on the effect of grain size on formation of Griffiths phase (GP), and glassy mixed phase in CE-type antiferromagnetic Sm 0.5 Ca 0.5 MnO 3

  8. Phase transition in the (Li 0.5-( x/2) K 0.5-( x/2) Cs x) 2SO 4 system

    Science.gov (United States)

    Hamed, A. E.; El-Aziz, Y. M. Abd.; Madi, N. K.; Kassem, M. E.

    1995-12-01

    Phase transition in the (Li 0.5-( x/2) K 0.5-( x/2) Cs x) 2SO 4 system was studied by measuring the specific heat at constant pressure, C p, as a function of temperature in the temperature range 300-800 K. For non-zero values of X ( X = 0.2%, 0.5%, 1% and 2%) the critical behaviour of the phase transition was found to change considerably compared with that of X = 0 or pure LiKSO 4. The observed change in the phase transition with increase of Cs 2SO 4 content ( X) was accompanied by a decrease in the thermodynamic parameters: the value of the specific heat at the transition point (Δ C P) max, the transition temperature, T1, and the value of the energy of ordering. The results were interpreted within the Landau thermodynamic theory of the phase transition.

  9. Effects of thermal and electrical histories on structure and dielectric behaviors of (Li0.5Nd0.52+-modified (Bi0.5Na0.5TiO3-BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Jiwen Xu

    2017-06-01

    Full Text Available The effect of thermal and electrical histories on structure and dielectric behaviors is studied using 0.95(Bi0.5Na0.50.97(Li0.5Nd0.50.03TiO3-0.05BaTiO3 (abbreviated as BNTLN0.03-BT5 ceramic as a selected system. Subtle structure change caused by annealing treatment, and pronounced phase transition and domain switching by electrical poling, are observed to occur, respectively. The dielectric constant and its strong frequency dispersion in unpoled samples decrease evidently by electrical poling due to electric field-induced ordered domain. The high temperature Maxwell-Wagner relaxor behavior vanishes by annealing treatment due to the loss of electrical inhomogeneity with interface charging effects. Piezoelectric properties are improved evidently by annealing treatment at 900 °C, implying a new appropriate method to improve piezoelectric properties.

  10. Insight into cation disorder of Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Bini, Marcella [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy); Ferrari, Stefania, E-mail: stefania.ferrari@unipv.it [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy); Capsoni, Doretta; Spreafico, Clelia; Tealdi, Cristina; Mustarelli, Piercarlo [Dept. of Chemistry, University of Pavia, viale Taramelli 16, Pavia 27100 (Italy)

    2013-04-15

    Transition metal lithium orthosilicates are promising cathode materials for lithium-ion batteries. Here we report a combined experimental (in situ X-ray diffraction) and computational (static lattice and molecular dynamics) study of the thermal behavior of the Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4} orthosilicate from room temperature to 950 °C. Our X-ray results showed that Pmnb polymorph is the most stable all over the explored temperature range. A significant cation disorder up to 80%, based on the anti-site defect, was found. The defect concentration depends on the synthesis route and temperature, and is completely reversible after the thermal treatments. Moreover, a careful analysis of the impurity phases allowed us to identify Li{sub 2}SiO{sub 3}, Fe{sub 3}O{sub 4} and Li{sub 3}Fe{sub 5}O{sub 8}, the last one never reported before. The minimization of defects by opportunely tuning the synthetic parameters would be of great importance in view of potential applications of these materials in lithium batteries. - Graphical abstract: A combined experimental in situ X-ray diffraction and computational study of the thermal behavior of the Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4} is reported herein. The anti-site defect does justify the diffraction patterns changes with temperature. Highlights: ► Study of the thermal behavior of Li{sub 2}Fe{sub 0.5}Mn{sub 0.5}SiO{sub 4}. ► The anti-site defect does justify the diffraction patterns changes with temperature. ► The Pmnb polymorph is stable in the investigated temperaturerange.

  11. Local magnetic properties of multiferroic Nd0.5Gd0.5Fe3(BO3)4 in the excited states of Nd3+ ion

    International Nuclear Information System (INIS)

    Malakhovskii, A.V.; Gnatchenko, S.L.; Kachur, I.S.; Piryatinskaya, V.G.; Sukhachev, A.L.; Temerov, V.L.

    2015-01-01

    Polarized absorption spectra of single-crystal Nd 0.5 Gd 0.5 Fe 3 (BO 3 ) 4 were studied in the region of the transition 4 I 9/2 →( 4 G 5/2 + 2 G 7/2 ) in Nd 3+ ion as a function of temperature (2–34 K) and magnetic field (0–65 kOe). The spectra of natural circular dichroism were measured in the range of 5–40 K. It was found out that the local magnetic properties in the vicinity of the excited ion substantially depended on its state. In particular, a weak ferromagnetic moment appears in some excited states. It was found out that the selection rules for electron transitions in the magnetically ordered state substantially deviated from those in the paramagnetic state of the crystal. They are different for different transitions and they are very sensitive to the orientation of the sublattice magnetic moment relative to the light polarization. In the spectrum of the natural circular dichroism, the transition is revealed which is not observed in the absorption spectrum. - Highlights: • Temperature and field dependences of f-f transitions in Nd 0.5 Gd 0.5 Fe 3 (BO 3 ) 4 . • Natural circular dichroism in Nd 0.5 Gd 0.5 Fe 3 (BO 3 ) 4 below T N . • Weak ferromagnetic moment was identified in some excited 4f states. • Selection rules for f-f transitions substantially change below T N . • Intensities of f-f transitions strongly depend on magnetic moment orientation

  12. Enhanced Photocatalytic Hydrogen Evolution by Loading Cd0.5Zn0.5S QDs onto Ni2P Porous Nanosheets.

    Science.gov (United States)

    Xiao, Lingfeng; Su, Tong; Wang, Zhuo; Zhang, Kun; Peng, Xiaoniu; Han, Yibo; Li, Quan; Wang, Xina

    2018-02-02

    Ni 2 P has been decorated on CdS nanowires or nanorods for efficient photocatalytic H 2 production, whereas the specific surface area remains limited because of the large size. Here, the composites of Cd 0.5 Zn 0.5 S quantum dots (QDs) on thin Ni 2 P porous nanosheets with high specific surface area were constructed for noble metal-free photocatalytic H 2 generation. The porous Ni 2 P nanosheets, which were formed by the interconnection of 15-30 nm-sized Ni 2 P nanoparticles, allowed the uniform loading of 7 nm-sized Cd 0.5 Zn 0.5 S QDs and the loading density being controllable. By tuning the content of Ni 2 P, H 2 generation rates of 43.3 μM h - 1 (1 mg photocatalyst) and 700 μM h - 1 (100 mg photocatalyst) and a solar to hydrogen efficiency of 1.5% were achieved for the Ni 2 P-Cd 0.5 Zn 0.5 S composites. The effect of Ni 2 P content on the light absorption, photoluminescence, and electrochemical property of the composite was systematically studied. Together with the band structure calculation based on density functional theory, the promotion of Ni 2 P in charge transfer and HER activity together with the shading effect on light absorption were revealed. Such a strategy can be applied to other photocatalysts toward efficient solar hydrogen generation.

  13. Investigation of structural and magnetic properties of Ni0.5Zn0.5Fe2O4 nano powders prepared by self combustion method

    International Nuclear Information System (INIS)

    Sudheesh, V.D.; Nehra, J.; Vinesh, A.; Sebastian, V.; Lakshmi, N.; Dutta, Dimple P.; Reddy, V.R.; Venugopalan, K.; Gupta, Ajay

    2013-01-01

    Graphical abstract: Display Omitted Highlights: ► Ni 0.5 Zn 0.5 Fe 2 O 4 prepared by self combustion with uniform/nonuniform heating. ► Characterized using TEM, XRD, in-field Mössbauer and DC magnetometry. ► Leads to bimodal (S1) and very narrow size distribution (S2) type nano samples. ► S1 has magnetic properties of bulk Ni 0.5 Zn 0.5 Fe 2 O 4 . ► Although very even sized, S2 large magnetic anisotropy distribution. -- Abstract: Nano powders of Ni 0.5 Zn 0.5 Fe 2 O 4 have been synthesized by the self-combustion method at a relatively low temperature of 473 K under conditions of non-uniform and uniform heating. Rietveld fitting of X-ray diffractograms confirm the formation of the pure spinel phase in both samples. Transmission electron microscopy indicates that the sample prepared under non-uniform heating has a bimodal particle size distribution (average values 16 nm and 6 nm) while the one prepared under uniform heating has a very narrow particle size distribution (average size 4 nm). Low temperature, in-field Mössbauer spectroscopic studies clearly show surface spin contributions. The hyperfine fields and Curie temperature of the non-uniformly heated sample are in good agreement with those reported for the corresponding bulk samples. Despite having a very narrow particle size distribution, the uniformly heated sample has a large anisotropy distribution which is evident in the broad transition visible in the temperature dependent magnetization curve. It is also corroborated by the fact that the experimental magnetization curve at room temperature requires two Langevin functions for satisfactory reproduction.

  14. Obtainment the reverse phase spinel [Zn2+0,5Fe3+0,5](Ni2+0,5Fe3+ 1,5)O4 by the method combustion reaction: the form of assessment heating

    International Nuclear Information System (INIS)

    Silva, M.C.; Costa, A.C.F.; Coutinho, J.P.; Silva, A.T.C.; Freitas, N.L.

    2011-01-01

    This paper aims to synthesize the inverse spinel phase of by combustion reaction method and to evaluate how [Zn 2+ 0,5Fe 3+ 0,5](Ni 2+ 0,5Fe 3+ 1,5)O 4 the heat source influences the structural and morphological this phase. The forms of heating were muffle oven and ceramic plate with built-in resistance and aniline as reducing agent. Comparisons were made between temperature, reaction time and physical changes undergone by the material during the combustion carried out in two warm-up. The material was characterized by XRD, SEM, and textural analysis. Based on the results showed that the spinel phase was successfully obtained, were found traces of the phases ZnO and Fe2O3. The Most crystallite size and higher reaction temperature were presented by the material produced in the plate. As for surface area and pore volume, the highest values were achieved by the material synthesized in the oven. The agglomerates were presented in the form of skeins made of pre-sintered particles. (author)

  15. Synthesis and structural studies of Mg doped LiNi0.5Mn0.5O2 cathode materials for lithium-ion batteries

    Science.gov (United States)

    Murali, N.; Margarette, S. J.; Madhuri Sailaja, J.; Kondala Rao, V.; Himakar, P.; Kishore Babu, B.; Veeraiah, V.

    2018-02-01

    Layered Mg doped LiNi0.5Mn0.5O2 materials have been synthesized by sol-gel method. The physical properties of these materials were examined by XRD, FESEM and FT-IR studies. From XRD patterns, the phase formation of α-NaFeO2 layered structure with R\\bar 3m space group is confirmed. The surface morphology of the synthesized materials has been examined by FESEM analysis in which the average particle size is found to be about 2 - 2.5 µm. These materials show some changes in the local ion environment, as examined by FT-IR studies.

  16. Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data

    OpenAIRE

    Fan Zhang; Oleg N. Senkov; Jonathan D. Miller

    2013-01-01

    Microstructure and phase composition of a CrMo0.5NbTa0.5TiZr high entropy alloy were studied in the as-solidified and heat treated conditions. In the as-solidified condition, the alloy consisted of two disordered BCC phases and an ordered cubic Laves phase. The BCC1 phase solidified in the form of dendrites enriched with Mo, Ta and Nb, and its volume fraction was 42%. The BCC2 and Laves phases solidified by the eutectic-type reaction, and their volume fractions were 27% and 31%, respectively....

  17. Superconducting properties of Zn and Al double-doped Mg1-x(Zn0.5Al0.5)xB2

    DEFF Research Database (Denmark)

    Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

    2004-01-01

    (XRD), ac susceptibility, magnetization and resistivity. The double doping leads to decreases in both the lattice parameters a and c, and the T-c decreases with increasing dopant content. A systematical comparison with Al doped- and Li, Al double doped MgB2 of structure, superconducting transition......A series of polycrystalline samples of Mg1-x(Zn0.5Al0.5)(x)B-2 (0less than or equal toxless than or equal to0.8) were prepared by solid state reaction method and their structure, superconducting transition temperature (T-c) and transport properties were investigated by means of X-ray diffraction...

  18. 139La NMR evidence for sensitivity of local structure to magnetic field in La0.5Ca0.5MnO3

    International Nuclear Information System (INIS)

    Yoshinari, Y.; Hammel, P.C.; Thompson, J.D.; Cheong, S.

    1999-01-01

    We report 139 La nuclear-magnetic-resonance measurements on La 0.5 Ca 0.5 MnO 3 . Two resonance peaks observed in zero applied field are identified as ferromagnetic (FM) resonances arising from FM domains with eight nearest Mn moments almost fully polarized. The two La sites are distinguished by experiencing different covalent configurations with respect to the nearest Mn ions, likely caused by the charge/orbital ordering. The two sites collapse into one in the presence of a strong magnetic field, indicating the close relationship between magnetism and the lattice deformation. copyright 1999 The American Physical Society

  19. Mechanical behaviour of Br0.5Sr0.5Co0.8Fe0.2O3-δ under uniaxial compression

    International Nuclear Information System (INIS)

    Araki, Wakako; Malzbender, Jürgen

    2013-01-01

    The present study reports on the mechanical behaviour of Br 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ under uniaxial compression at various temperatures. The stress–strain curve at room temperature shows a small but clear creep deformation, along with a hysteresis and a remnant strain, which could be related to a spin transition of cobalt. The hysteresis as well as Young’s modulus decrease with increasing temperature to 473 K, at which temperature the creep behaviour disappears. The material shows conventional high-temperature creep above 673 K

  20. Electric and magnetic fields effects on the transport properties of La0.5Ca0.5MnO3 thin films

    International Nuclear Information System (INIS)

    Villafuerte, M.; Duhalde, S.; Rubi, D.; Bridoux, G.; Heluani, S.; Sirena, M.; Steren, L.

    2004-01-01

    The insulator to metal transition in manganites can be drastically influenced by internal factors, such as chemical composition, or under a variety of external perturbations, like magnetic or electric fields. In this work, the electrical resistance of La 0.5 Ca 0.5 MnO 3 thin films was investigated using different constant voltages. At low temperature the conductivity of the films is non-Ohmic and moderate electric fields results in resistivity switching to metastable states. Comparisons between the influence of magnetic and electric fields on transport measurements are reported

  1. Intrinsic colossal magnetoresistance effect in thin-film Pr0.5Sr0.5MnO3 through dimensionality switching.

    Science.gov (United States)

    Uozu, Y; Wakabayashi, Y; Ogimoto, Y; Takubo, N; Tamaru, H; Nagaosa, N; Miyano, K

    2006-07-21

    A homogeneous colossal magnetoresistance (CMR) effect at low temperatures has been found in a thin-film perovskite manganite Pr0.5Sr0.5MnO3. The transition is driven not by the spin alignment as in usual CMR in bulk samples but by the localization-delocalization transition switched by the change in the effective dimensionality. Two-dimensional (x2-y2)-orbital ordering enhanced by the substrate strain is essential for the stabilization of the insulating localized state, which is on the verge of the first-order transition to the three-dimensional metallic ferromangetic state.

  2. Structural study of the semimagnetic semiconductor Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Sagredo, V. [Laboratorio de Magnetismo en Solidos, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela)

    2009-02-15

    The semimagnetic semiconductor alloy Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4} was refined from an X-ray powder diffraction pattern using the Rietveld method. This compound crystallizes in the space group I anti 42m (N {sup circle} 121), Z=2, with unit cell parameters a=6.1738(1)A, c=12.3572(4)A, V=471.00(2)A3, c/a=2.00. This material crystallizes in a stannite-type structure. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Depairing current density of Ba0.5K0.5Fe1.95Co0.05As2 microbridges with nanoscale thickness

    International Nuclear Information System (INIS)

    Li, Jun; Yuan, Jie; Ge, Jun-Yi; Ji, Min; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Vanacken, Johan; Yamaura, Kazunari; Wang, Hua-Bing

    2014-01-01

    Highlights: • The critical current density of Ba 0.5 K 0.5 Fe 1.95 Co 0.05 As 2 microbridges is 7.9 MA/cm 2 at 21 K. • The critical current is in consistence with the Ginzburg–Landau depairing limit. • The depairing current density is less than that of impurity-free crystal. - Abstract: We investigated the depairing current density of Ba 0.5 K 0.5 Fe 1.95 Co 0.05 As 2 microbridges with width of 2 μm and thickness of 150 nm. The current vs. voltage characteristics of the microbridges show a Josephson-like behavior with the obvious hysteresis. The critical current density was observed as J c = 7.9 MA/cm 2 at temperature 21 K, which is consistent with the Ginzburg–Landau depairing limit. However, the depairing current density is less than that of impurity-free crystal, although the Co ions provide additional pinning centers within the superconducting Fe 2 As 2 layers. The Co impurity also enhances the anisotropic factor of the critical current density by 1.3 (1 T) or 1.7 (3 T)

  4. Temperature-dependent leakage current behavior of epitaxial Bi0.5Na0.5TiO3-based thin films made by pulsed laser deposition

    Science.gov (United States)

    Hejazi, M. M.; Safari, A.

    2011-11-01

    This paper discusses the electrical conduction mechanisms in a 0.88 Bi0.5Na0.5TiO3-0.08 Bi0.5K0.5TiO3-0.04 BaTiO3 thin film in the temperature range of 200-350 K. The film was deposited on a SrRuO3/SrTiO3 substrate by pulsed laser deposition technique. At all measurement temperatures, the leakage current behavior of the film matched well with the Lampert's triangle bounded by three straight lines of different slopes. The relative location of the triangle sides varied with temperature due to its effect on the density of charge carriers and un-filled traps. At low electric fields, the ohmic conduction governed the leakage mechanism. The calculated activation energy of the trap is 0.19 eV implying the presence of shallow traps in the film. With increasing the applied field, an abrupt increase in the leakage current was observed. This was attributed to a trap-filling process by the injected carriers. At sufficiently high electric fields, the leakage current obeyed the Child's trap-free square law suggesting the space charge limited current was the dominant mechanism.

  5. Microstructure and mechanical behavior of superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N biomedical alloys.

    Science.gov (United States)

    Ramarolahy, A; Castany, P; Prima, F; Laheurte, P; Péron, I; Gloriant, T

    2012-05-01

    In this study, the microstructure and the mechanical properties of two new biocompatible superelastic alloys, Ti-24Nb-0.5O and Ti-24Nb-0.5N (at.%), were investigated. Special attention was focused on the role of O and N addition on α(″) formation, supereleastic recovery and mechanical strength by comparison with the Ti-24Nb and Ti-26Nb (at.%) alloy compositions taken as references. Microstructures were characterized by optical microscopy, X-ray diffraction and transmission electron microscopy before and after deformation. The mechanical properties and the superelastic behavior were evaluated by conventional and cyclic tensile tests. High tensile strength, low Young's modulus, rather high superelastic recovery and excellent ductility were observed for both superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N alloys. Deformation twinning was shown to accommodate the plastic deformation in these alloys and only the {332} twinning system was observed to be activated by electron backscattered diffraction analyses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2013-09-01

    Full Text Available Microstructure and phase composition of a CrMo0.5NbTa0.5TiZr high entropy alloy were studied in the as-solidified and heat treated conditions. In the as-solidified condition, the alloy consisted of two disordered BCC phases and an ordered cubic Laves phase. The BCC1 phase solidified in the form of dendrites enriched with Mo, Ta and Nb, and its volume fraction was 42%. The BCC2 and Laves phases solidified by the eutectic-type reaction, and their volume fractions were 27% and 31%, respectively. The BCC2 phase was enriched with Ti and Zr and the Laves phase was heavily enriched with Cr. After hot isostatic pressing at 1450 °C for 3 h, the BCC1 dendrites coagulated into round-shaped particles and their volume fraction increased to 67%. The volume fractions of the BCC2 and Laves phases decreased to 16% and 17%, respectively. After subsequent annealing at 1000 °C for 100 h, submicron-sized Laves particles precipitated inside the BCC1 phase, and the alloy consisted of 52% BCC1, 16% BCC2 and 32% Laves phases. Solidification and phase equilibrium simulations were conducted for the CrMo0.5NbTa0.5TiZr alloy using a thermodynamic database developed by CompuTherm LLC. Some discrepancies were found between the calculated and experimental results and the reasons for these discrepancies were discussed.

  7. A high performance Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel

    Science.gov (United States)

    Li, Wei; Liu, Hongxia; Wang, Shulong; Wang, Qianqiong; Chen, Shupeng

    2017-06-01

    In this paper, a new Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel (Ge_DUTFET) is proposed and investigated by Silvaco-Atlas simulation. The line tunneling perpendicular to channel and point tunneling parallel to channel simultaneously occur on both sides of the gate. The Ge is chosen as the source region material to increase the line tunneling current. The designed heterojunction between the Ge source and Si channel decreases the point tunneling barrier width to enhance the point tunneling current. And this heterojunction can also promote the Ge_DUTFET to occur point tunneling at the small gate voltage, which makes it obtain the smaller turn-on voltage. Furthermore, the Si0.5Ge0.5 buffer layer is also helpful for the enhancement of performance. The simulation results reveal that Ge_DUTFET has the better performance compared with the Si_DUTFET. The on-state current and average subthreshold swing of Ge_DUTFET are 1.11 × 10-5A/μm and 35.1mV/dec respectively. The max cut-off frequency (fT) and gain bandwidth product (GBW) are 26.6 GHz and 16.6 GHz respectively. The fT and GBW of the Ge_DUTFET are respectively increased by ∼27.4% and ∼84.3% compared with the Si_DUTFET.

  8. Thermal-induced structural transition and depolarization behavior in (Bi0.5Na0.5)TiO3-BiAlO3 ceramics

    Science.gov (United States)

    Peng, Ping; Nie, Hengchang; Cheng, Guofeng; Liu, Zhen; Wang, Genshui; Dong, Xianlin

    2018-03-01

    The depolarization temperature Td determines the upper temperature limit for the application of piezoelectric materials. However, the origin of depolarization behavior for Bi-based materials still remains controversial and the mechanism is intricate for different (Bi0.5Na0.5)TiO3-based systems. In this work, the structure and depolarization behavior of (1-x)(Bi0.5Na0.5)TiO3-xBiAlO3 (BNT-BA, x = 0, 0.02, 0.04, 0.06, 0.07) ceramics were investigated using a combination of X-ray diffraction and electrical measurements. It was found that as temperature increased, the induced long-range ferroelectric phase irreversibly transformed to the relaxor phase as evidenced by the temperature-dependent ferroelectric and dielectric properties, which corresponded to a gradual structural change from the rhombohedral to the pseudocubic phase. Therefore, the thermal depolarization behavior of BNT-BA ceramics was proposed to be directly related to the rhombohedral-pseudocubic transition. Furthermore, Td (obtained from thermally stimulated depolarization currents curves) was higher than the induced ferroelectric-relaxor phase transition temperature TFR (measured from dielectric curves). The phenomenon was quite different from other reported BNT-based systems, which may suggest the formation of polar nanoregions (PNRs) within macrodomains prior to the detexturation of short-range ferroelectric domains with PNRs or nanodomains.

  9. Aurivillius-Popper mixed superconductors in BiO--CuO--(Sr/sub 0.5/, Ca/sub 0.5/)O system

    International Nuclear Information System (INIS)

    Fukuhara, M.; Bhalla, A.S.; Mulay, L.N.; Newnham, R.E.

    1989-01-01

    We report the effect of inhomogeneities on the electric resistivity and ac magnetic susceptibility in Aurivillius-like bismuth mixed phase oxides of the BiO--Cuo--(Sr/sub 0.5/, Ca/sub 0.5/)O system and propose a crystal structure of the major phase having highest T/sub c/. Nominal Aurivillius compositions with molar ratios of BiO/(Sr/sub 0.5/, Ca/sub 0.5/)O = 1/2 are superconductors with T/sub c/ ranging from 83 to 107 K, and are accompanied by a large expansion during sintering due to the formation of Kirkendall voids. T/sub c/ increases with decreasing of the c lattice parameter. An oxide BiSrCaCu 2 O/sub x/ (n = 2) shows a maximum T/sub c/ value of 107 K and an onset of superconductivity at a much higher temperature. It seems that the structure of Bi 2 Sr 2 CaCu 2 O/sub x/ consists of an Aurivillius-like phase having two perovskite layers and a Popper mixed phase. The ac magnetic susceptibility showed an overall decrease in susceptibility with time up to 220 days. This appears to be related to the relief of intralattice strain

  10. Effect of O- and Mn-doping on superconductivity in FeTe{sub 0.5}Se{sub 0.5} superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Gohil S.; Haque, Zeba; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Neha, Prakriti; Patnaik, Satyabrata [School of Physical Science, Jawaharlal Nehru University, New Delhi (India); Gupta, Laxmi C. [Department of Chemistry, Indian Institute of Technology, New Delhi (India); Visiting project scientist at the:Solid State and Nanomaterials Research Laboratory, Department of Chemistry, IIT Delhi (India)

    2014-05-15

    The effect of oxygen substitution at the selenium site and manganese substitution at the iron site in FeTe{sub 0.5}Se{sub 0.5} superconductor was investigated. It was found that upon partial O substitution, T{sub c} marginally decreases as seen in both resistivity and magnetization experiments. T{sub c} decreases even by a small amount of oxygen concentration (as low as 1 %). This observation is in contrast against an earlier work on Fe(Te/Se) samples,1 wherein T{sub c} as well as superconducting volume fraction were reported to increase in the samples annealed in air. Mn-doping leads to a decrease in T{sub c} in FeTe{sub 0.5}Se{sub 0.5}, which one would expect considering pair-breaking due to Mn{sup 2+}-ions. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Surface spin glass and exchange bias effect in Sm0.5Ca0.5MnO3 manganites nano particles

    Directory of Open Access Journals (Sweden)

    S. K. Giri

    2011-09-01

    Full Text Available In this letter, we report that the charge/orbital order state of bulk antiferromagnetic Sm0.5Ca0.5MnO3 is suppressed and confirms the appearance of weak ferromagnetism below 65 K followed by a low temperature spin glass like transition at 41 K in its nano metric counterpart. Exchange anisotropy effect has been observed in the nano manganites and can be tuned by the strength of the cooling magnetic field (Hcool. The values of exchange fields (HE, coercivity (HC, remanence asymmetry (ME and magnetic coercivity (MC are found to strongly depend on cooling magnetic field and temperature. HE increases with increasing Hcool but for larger Hcool, HE tends to decrease due to the growth of ferromagnetic cluster size. Magnetic training effect has also been observed and it has been analyzed thoroughly using spin relaxation model. A proposed phenomenological core-shell type model is attributed to an exchange coupling between the spin-glass like shell (surrounding and antiferromagnetic core of Sm0.5Ca0.5MnO3 nano manganites mainly on the basis of uncompensated surface spins. Results suggest that the intrinsic phase inhomogeneity due to the surface effects of the nanostructured manganites may cause exchange anisotropy, which is of special interests for potential application in multifunctional spintronic devices.

  12. Ion-exchange mechanism of layered transition-metal oxides: case study of LiNi(0.5)Mn(0.5)O₂.

    Science.gov (United States)

    Gwon, Hyeokjo; Kim, Sung-Wook; Park, Young-Uk; Hong, Jihyun; Ceder, Gerbrand; Jeon, Seokwoo; Kang, Kisuk

    2014-08-04

    An ion-exchange process can be an effective route to synthesize new quasi-equilibrium phases with a desired crystal structure. Important layered-type battery materials, such as LiMnO2 and LiNi(0.5)Mn(0.5)O2, can be obtained through this method from a sodium-containing parent structure, and they often show electrochemical properties remarkably distinct from those of their solid-state synthesized equivalents. However, while ion exchange is generally believed to occur via a simple topotactic reaction, the detailed phase transformation mechanism during the process is not yet fully understood. For the case of layered LiNi(0.5)Mn(0.5)O2, we show through ex situ X-ray diffraction (XRD) that the ion-exchange process consists of several sequential phase transformations. By a study of the intermediate phase, it is shown that the residual sodium ions in the final structure may greatly affect the electrochemical (de)lithiation mechanism.

  13. Structural, Dielectric, and Electrical Properties of Bi1- x Pb x Fe1- x (Zr0.5Ti0.5) x O3

    Science.gov (United States)

    Panda, Niranjan; Pattanayak, Samita; Choudhary, R. N. P.

    2015-12-01

    Polycrystalline samples of Bi1- x Pb x Fe1- x (Zr0.5Ti0.5) x O3 (BPFZTO) with x = 0.0, 0.2, 0.3, and 0.4 were prepared by high-temperature solid-state reaction. Preliminary structural analysis of calcined powders of the materials by use of x-ray powder diffraction confirmed formation of single-phase systems with the tetragonal structure. Room-temperature scanning electron micrographs of the samples revealed uniform distribution of grains of low porosity and different dimensions on the surface of the samples. The frequency-temperature dependence of dielectric and electric properties was studied by use of dielectric and complex impedance spectroscopy over a wide range of frequency (1 kHz to 1 MHz) at different temperatures (25-500°C). The dielectric constant of BiFeO3 (BFO) was enhanced by substitution with Pb(Zr0.5Ti0.5)O3 (PZT) whereas the dielectric loss of the BPFZTO compounds decreased with increasing PZT content. A significant contribution of both grains and grain boundaries to the electrical response of the materials was observed. The frequency-dependence of the ac conductivity of BPFZTO followed Jonscher's power law. Negative temperature coefficient of resistance behavior was observed for all the BPFZTO samples. Conductivity by thermally excited charge carriers and oxygen vacancies in the materials was believed to be of the Arrhenius-type.

  14. Estimation of Joule heating and its role in nonlinear electrical response of Tb0.5Sr0.5MnO3 single crystal

    Science.gov (United States)

    Nhalil, Hariharan; Elizabeth, Suja

    2016-12-01

    Highly non-linear I-V characteristics and apparent colossal electro-resistance were observed in non-charge ordered manganite Tb0.5Sr0.5MnO3 single crystal in low temperature transport measurements. Significant changes were noticed in top surface temperature of the sample as compared to its base while passing current at low temperature. By analyzing these variations, we realize that the change in surface temperature (ΔTsur) is too small to have caused by the strong negative differential resistance. A more accurate estimation of change in the sample temperature was made by back-calculating the sample temperature from the temperature variation of resistance (R-T) data (ΔTcal), which was found to be higher than ΔTsur. This result indicates that there are large thermal gradients across the sample. The experimentally derived ΔTcal is validated with the help of a simple theoretical model and estimation of Joule heating. Pulse measurements realize substantial reduction in Joule heating. With decrease in sample thickness, Joule heating effect is found to be reduced. Our studies reveal that Joule heating plays a major role in the nonlinear electrical response of Tb0.5Sr0.5MnO3. By careful management of the duty cycle and pulse current I-V measurements, Joule heating can be mitigated to a large extent.

  15. Electrical characteristics and preparation of (Ba0.5Sr0.5)TiO3 films by spray pyrolysis and rapid thermal annealing

    International Nuclear Information System (INIS)

    Koo, Horngshow; Ku, Hongkou; Kawai, Tomoji; Chen Mi

    2007-01-01

    Functional films of (Ba 0.5 Sr 0.5 )TiO 3 on Pt (1000 A)/Ti (100 A)/SiO 2 (2000 A)/Si substrates are prepared by spray pyrolysis and subsequently rapid thermal annealing. Barium nitrate, strontium nitrate and titanium isopropoxide are used as starting materials with ethylene glycol as solvent. For (Ba 0.5 Sr 0.5 )TiO 3 functional thin film, thermal characteristics of the precursor powder scratched from as-sprayed films show a remarkable peak around 300-400degC and 57.7% weight loss up to 1000degC. The as-sprayed precursor film with coffee-like color and amorphous-like phase is transformed into the resultant film with white, crystalline perovskite phase and characteristic peaks (110) and (100). The resultant films show correspondent increases of dielectric constant, leakage current and dissipation factor with increasing annealing temperatures. The dielectric constant is 264 and tangent loss is 0.21 in the resultant films annealed at 750degC for 5 min while leakage current density is 1.5x10 -6 A/cm 2 in the film annealed at 550degC for 5 min. (author)

  16. Structure and superconductivity of double-doped Mg1-x(Al0.5Li0.5)xB2

    DEFF Research Database (Denmark)

    Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

    2003-01-01

    A series of polycrystalline samples of Mg1-x(Al0.5Li0.5)(x)B-2 (0less than or equal toxless than or equal to0.6) were prepared by a solid state reaction method and their structure, superconducting transition temperature and magneto-transport properties were investigated by means of X-ray diffract......A series of polycrystalline samples of Mg1-x(Al0.5Li0.5)(x)B-2 (0less than or equal toxless than or equal to0.6) were prepared by a solid state reaction method and their structure, superconducting transition temperature and magneto-transport properties were investigated by means of X......-ray diffraction (XRD), ac-susceptibility and resistance in varied magnetic fields. The double doping leads to decreases in both the lattice parameters a and c. The superconducting transition temperature (T-c) decreases with double doping, but the T-c is systematically higher than that of the single Al......-doped samples. It is suggested that the hole band filling has little effect on T-c at high doping level, while the disorder induced by doping plays an important role in suppressing T-c. A systematic comparison with Al-doped MgB2 of the structure, superconducting transition and irreversibility field is made. (C...

  17. Coexistence of room temperature ferroelectricity and ferrimagnetism in multiferroic BiFeO3-Bi0.5Na0.5TiO3 solid solution

    International Nuclear Information System (INIS)

    Tian, Z.M.; Wang, C.H.; Yuan, S.L.; Wu, M.S.; Ma, Z.Z.; Duan, H.N.; Chen, L.

    2011-01-01

    Highlights: → In this study, the coexistence of ferroelectrics and ferrimagnetism have been observed at room temperature for the (1 - x)BiFeO 3 -xBi 0.5 Na 0.5 TiO 3 (x = 0.37) solid solutions. → X-ray diffraction and Raman spectroscopy measurements show a single-phase perovskite structure with no impurities identified. → A magnetic transition from paramagnetic (PM) to ferrimagnetic (Ferri) ordering is observed for the solution with Curie temperature T C ∼ 330 K. - Abstract: The structure, ferroelectric and magnetic properties of (1 - x)BiFeO 3 -xBi 0.5 Na 0.5 TiO 3 (x = 0.37) solid solution fabricated by a sol-gel method have been investigated. X-ray diffraction and Raman spectroscopy measurements show a single-phase perovskite structure with no impurities identified. Compared with pure BiFeO 3 , the coexistence of ferroelectricity and ferrimagnetism have been observed at room temperature for the solution with remnant polarization P r = 1.41 μC/cm 2 and remnant magnetization M r = 0.054 emu/g. Importantly, a magnetic transition from ferrimagnetic (FM) ordering to paramagnetic (PM) state is observed, with Curie temperature T C ∼ 330 K, being explained in terms of the suppression of cycloid spin configuration by the structural distortion.

  18. Study of the behavior of the compound Mg2Ni0.5Co0.5 front to hydriding process

    International Nuclear Information System (INIS)

    Martinez, C; Ordonez, S; Serafini, D; Guzman, D; Bustos, O

    2012-01-01

    This paper study the behavior of the compound Mg 2 Ni 0,5 Co 0,5 during the hydriding process. Elemental powders of Mg, Ni and Co, with an atomic ratio of 2:0,5:0,5 were mechanically alloyed using a high energy mill SPEX 8000D for 36h. The amorphous and crystalline structure of the samples was characterized through X-ray diffraction The hydriding process was performed by the volumetric technique Sievert at 90 o C and a pressure of 20 bar H 2 . The desorption process was evaluated by differential scanning calorimetry. Based on the results we can conclude that the amorphous structure absorbs more hydrogen, reaching a maximum of 3.6 wt% H2, besides the incorporation of cobalt act as catalyst for the absorption of H2 obtaining values higher than those reported in the Mg-Ni system amorphous state. The desorption process is influenced by the type of structure that presents the alloy

  19. Effect of Co substitution on magnetic ground state in Sm0.5Ca0.5MnO3

    International Nuclear Information System (INIS)

    Xu, Xiaolong; Li, Yu; Hou, Feifei; Cheng, Qian; Su, Runzhou

    2015-01-01

    Highlights: • Polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 were prepared by standard solid-state reaction. • The orthorhombic deformation and normalized slope were calculated for each sample. • Critical slowing down model and dynamic scaling equation are applied in some samples. • Canted antiferromagnetic state via spin glass state, changes to ferrimagnetic state. - Abstract: The effect of cobalt doping on the structural and magnetic properties of polycrystalline Sm 0.5 Ca 0.5 Mn 1−x Co x O 3 (0 ⩽ x ⩽ 0.20) has been studied. Powder X-ray diffraction (XRD), dc magnetization and ac susceptibility measurements have been performed. The orthorhombic deformation caused by the Jahn–Teller (JT) effect can be counterbalanced by Co 3+ doping. Meanwhile, antiferromagnetic (AFM), spin glass (SG) and phase separation (PS) ferrimagnetic states appear, successively, with the increase of x. The critical slowing down model and the dynamic scaling equation were applied in some samples. The existence of two distinct length scales for SG and finite FM (ferromagnetic) order is the source of the progressive deviation which exists in the dynamic scaling fitting for x = 0.05. Moreover, the small peaks at ∼8 K in χ″(T) curves are believed to be induced by the canted moments of Mn ions as observed in Nd 2/3 Ca 1/3 MnO 3

  20. Europium substitution effects on structural, magnetic and magnetocaloric properties in La0.5Ca0.5MnO3

    Directory of Open Access Journals (Sweden)

    Boujelben W.

    2012-06-01

    Full Text Available We have investigated structural, magnetic and magnetocaloric properties of polycrystalline samples La0.5-xEuxCa0.5MnO3 (x=0 and 0.1. Rietveld refinement of the X-ray diffraction patterns show that our samples are single phase and crystallize in the orthorhombic structure with Pnma space group. Magnetization measurements versus temperature at a magnetic applied field of 500 Oe indicate that La0.4Eu0.1Ca0.5MnO3 sample exhibits a paramagnetic to ferromagnetic transition with decreasing temperature. Magnetic measurements reveal strong magnetocaloric effect in the vicinity of the Curie temperature TC. The parent compound shows a negative magnetic entropy change of ∆SM=−1.13Jkg−1K−1 at 220K and a positive magnetocaloric effects ∆SM=1Jkg−1K−1 at 150K under a magnetic applied field of 2T. La0.4Eu0.1Ca0.5MnO3 exhibits a maximum value of magnetic entropy change ∆SM=−1.15Jkg−1K−1 at 130K under an applied field of 2T and a large relative cooling power RCP with a maximum value of 72 J/kg.

  1. Mechanical bending strength of (Bi0.5Na0.5 TiO3-based lead-Free piezoelectric ceramics

    Directory of Open Access Journals (Sweden)

    Hiroaki Takahashi

    2017-09-01

    Full Text Available (Bi0.5Na0.5TiO3 [BNT] is expected as one of candidate lead-free materials because these ceramics show relatively good high-power piezoelectric properties. In this study, we tried to understand the bending strength and fracture behavior of the BNT-based ceramics. To measure the bending strength, a three-point bending test on the basis of JIS was conducted using 12.0 × 4.0 × 1.0 mm3 specimens. An average bending strength, σA, of pure BNT ceramics sintered at 1100 °C for 2, 12 and 24 h were 217, 195 and 187 MPa, respectively. It is cleared that the σA increased with decreasing the sintering time, (grain size and pore size. We also investigated the bending strength of Nb2O5 doped BNT ceramics [BNT-Nb x, x = 0.05 ∼ 1.5 wt%] and MnCO3 doped BNT ceramics [BNT-Mn x, x = 0.5 and 1.0 wt%]. Values of the σA of BNT-Nb 0.5 and BNT-Mn 0.5 were 222, and 188 MPa, respectively. It is clarified that soft dopants (Nb can improve the bending strength of BNT-based ceramics. Additionally, hot-pressed BNT [HP-BNT] were sintered at 1050 °C for 5 h, and the σA of HP-BNT was 245 MPa.

  2. Transfer in the light Hg isotopes and the U(6/12) models

    International Nuclear Information System (INIS)

    Vergnes, M.; Grafeuille, S.; Rotbard, G.

    1985-01-01

    It was suggested recently that the level schemes of the odd Hg isotopes with 193 200 Hg, 198 Hg, 196 Hg(p,d) 199 Hg, 197 Hg, 195 Hg. The comparison of the experimental spectroscopic factors with the ones computed using the U(6/12) model shows that, among the three nuclei studied, 195 Hg and 197 Hg can be considered as reasonably described. The agreement in this case with U(6/12) is better in the U(5) limit than in the O(6) limit

  3. Synthesis and characterization of the novel rare earth orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Schildhammer, Daniel; Petschnig, Lucas L.; Fuhrmann, Gerda; Heymann, Gunter; Schottenberger, Herwig; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Tribus, Martina [Innsbruck Univ. (Austria). Inst. fuer Mineralogie und Petrographie

    2016-02-01

    The new mixed rare earth (RE) orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} were synthesized by a classical solid state reaction in an electrical furnace at 1200 C. As starting materials, the corresponding rare earth oxides and diammonium hydrogen phosphate were used. The powder diffraction analyses revealed that the new compounds Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} crystallize in a zircon-type structure being isostructural with the rare earth orthophosphate YPO{sub 4}. Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} crystallize in the tetragonal space group I4{sub 1}/amd (no. 141) with four formula units in the unit cell. The structural parameters based on Rietveld refinements are a = 687.27(2), c = 601.50(2) pm, V = 0.28412(1) nm{sup 3}, R{sub p} = 0.0143, and R{sub wp} = 0.0186 (all data) for Y{sub 0.5}Er{sub 0.5}PO{sub 4} and a = 684.61(2), c = 599.31(2) pm, V = 0.28089(2) nm{sup 3}, R{sub p} = 0.0242, and R{sub wp} = 0.0313 (all data) for Y{sub 0.5}Yb{sub 0.5}PO{sub 4}. Furthermore, the structure of Y{sub 0.5}Er{sub 0.5}PO{sub 4} was refined from single-crystal X-ray diffraction data: a = 687.78(5), c = 601.85(4) pm, V = 0.28470(5) nm{sup 3}, R{sub 1} = 0.0165, and wR{sub 2} = 0.0385 (all data). In both compounds, the rare earth metal ions are eightfold coordinated by oxygen atoms, forming two unique interlocking tetrahedra with two individual RE-O distances. The tetrahedral phosphate groups [PO{sub 4}]{sup 3-} are slightly distorted in both compounds. The individual rare earth ions share a common position (Wyckoff site 4a). The presence of two rare earth ions in the structures of the new orthophosphates Y{sub 0.5}Er{sub 0.5}PO{sub 4} and Y{sub 0.5}Yb{sub 0.5}PO{sub 4} was additionally confirmed by single-crystal EDX spectroscopy revealing a ratio of 1:1.

  4. Effect of A-site substitution on crystal component and dielectric properties in Bi0.5Na0.5TiO3 ceramics

    International Nuclear Information System (INIS)

    Qu Yanfang; Shan Dan; Song Jianjing

    2005-01-01

    A-site replacement is common used in optimizing the electric properties of Bi 0.5 Na 0.5 TiO 3 (abbreviated to BNT). The effect of Ba 2+ doping in BNT capacitor ceramics is investigated here. After the samples containing 6 at.% Ba 2+ was sintered at 1180 deg. C for 2 h, capacitor ceramics with enhanced dielectric properties was fabricated, compared with pure BNT ceramics. It can be concluded from the experiment results that Ba 2+ replaced the ions in A-site, and the lattice structure was altered, which led to the improvement of dielectric properties in BNT ceramics. Then we discussed the phase transformation process from room temperature to 400 deg. C according to the dielectric properties-temperature graphs

  5. Size Effects on Magnetic Properties of Ni0.5Zn0.5Fe2O4 Prepared by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2013-01-01

    Full Text Available Ni0.5Zn0.5Fe2O4 particles with different particle sizes have been synthesized by sol-gel method. X-ray diffraction results show that all the samples are pure cubic spinel structure with their sizes ranging from 9 to 96 nm. The lattice constant significantly decreases with further increasing annealing temperature. The magnetic measurements show superparamagnetic nature below the particle size of 30 nm, while others show ferrimagnetic nature above the corresponding blocking temperature. The blocking temperature increases with the increase in particle size, which can be explained by Stoner-Wohlfarth theory. The saturation magnetization increases as the particle size increases, which can be explained by the cation redistribution on tetrahedral A and octahedral B sites and the domain wall motion. The variation of coercivity as a function of particle size is based on the domain structure.

  6. Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

    International Nuclear Information System (INIS)

    Li, D Z; Xu, X D; Wu, F; Xia, C T; Zhang, J; Ma, J; Cong, Z H; Tang, D Y; Zhu, H M; Chen, X Y; Xu, J

    2011-01-01

    A Nd:(Lu 0.5 Gd 0.5 ) 2 SiO 5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω 2,4,6 were obtained to be 5.37, 1.63, and 5.57×10 -20 cm 2 , respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained

  7. Growth, spectral properties, and laser demonstration of Nd:(Lu0.5Gd0.5)2SiO5 crystal

    Science.gov (United States)

    Li, D. Z.; Xu, X. D.; Zhang, J.; Cong, Z. H.; Tang, D. Y.; Ma, J.; Zhu, H. M.; Chen, X. Y.; Wu, F.; Xia, C. T.; Xu, J.

    2011-09-01

    A Nd:(Lu0.5Gd0.5)2SiO5 (Nd:LGSO) crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intensity parameters Ω2,4,6 were obtained to be 5.37, 1.63, and 5.57×10-20 cm2, respectively. The absorption and emission cross sections and branching ratios were calculated. The Nd:LGSO crystal reveals a broadband emission feature (FWHM = 9.8 nm), which shows potential as gain medium for ultrashort pulse lasers. The radiative and fluorescence lifetimes are 299 and 230 μs, respectively, resulting in a quantum efficiency of 77%. Pumped by a laser diode, the maximum continuous wave (CW) output power of 444 mW and a slope efficiency of 17.7% have been obtained.

  8. Fabrication of Fe1.1Se0.5Te0.5 bulk by a high energy ball milling technique

    Science.gov (United States)

    Liu, Jixing; Li, Chengshan; Zhang, Shengnan; Feng, Jianqing; Zhang, Pingxiang; Zhou, Lian

    2017-11-01

    Fe1.1Se0.5Te0.5 superconducting bulks were successfully synthesized by a high energy ball milling (HEBM) aided sintering technique. Two advantages of this new technique have been revealed compared with traditional solid state sintering method. One is greatly increased the density of sintered bulks. It is because the precursor powders with β-Fe(Se, Te) and δ-Fe(Se, Te) were obtained directly by the HEBM process and without formation of liquid Se (and Te), which could avoid the huge volume expansion. The other is the obvious decrease of sintering temperature and dwell time due to the effective shortened length of diffusion paths. The superconducting critical temperature Tc of 14.2 K in our sample is comparable with those in previous reports, and further optimization of chemical composition is on the way.

  9. Unraveling the magnetic properties of BiFe{sub 0.5}Cr{sub 0.5}O{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vinai, G.; Petrov, A. Yu.; Panaccione, G.; Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy); Khare, A. [CNR-SPIN Napoli and Dipartimento di Fisica, Università di Napoli “Federico II,” I-80126 Napoli (Italy); Department of Physics, Sungkyunkwan University, Suwon 440 746 (Korea, Republic of); Rana, D. S. [Department of Physics, Indian Institute of Science Education and Research Bhopal, Govindpura, Bhopal 462023 (India); Di Gennaro, E.; Scotti di Uccio, U.; Miletto Granozio, F. [CNR-SPIN Napoli and Dipartimento di Fisica, Università di Napoli “Federico II,” I-80126 Napoli (Italy); Gobaut, B. [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, Area Science Park, 34149 Trieste (Italy); Moroni, R. [CNR-SPIN, Corso Perrone 24, I-16152 Genova (Italy); Rossi, G. [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy); Department of Physics, Università degli Studi di Milano, via Celoria 16, I-20133 Milano (Italy)

    2015-11-01

    We investigate the structural, chemical, and magnetic properties on BiFe{sub 0.5}Cr{sub 0.5}O{sub 3} (BFCO) thin films grown on (001) (110) and (111) oriented SrTiO{sub 3} (STO) substrates by x-ray magnetic circular dichroism and x-ray diffraction. We show how highly pure BFCO films, differently from the theoretically expected ferrimagnetic behavior, present a very weak dichroic signal at Cr and Fe edges, with both moments aligned with the external field. Chemically sensitive hysteresis loops show no hysteretic behavior and no saturation up to 6.8 T. The linear responses are induced by the tilting of the Cr and Fe moments along the applied magnetic field.

  10. Strain profile and polarization enhancement in Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Amir, F.Z. [Physics Department, St John' s University, 8000 Utopia Pkwy, Jamaica, NY 11439 (United States); Donner, W. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Aspelmeyer, M. [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Noheda, B. [Department of Chemical Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Xi, X.X. [Physics Department, College of Science and Technology, Temple University, 1900 N.13th Street, Philadelphia, PA 19122 (United States); Moss, S.C. [Department of Physics, University of Houston, 617 Science and Research Building 1, Houston, Texas 77204-5005 (United States)

    2012-11-15

    The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Photoluminescence of polycrystalline CuIn 0.5 Ga 0.5 Te 2 thin films grown by flash evaporation

    KAUST Repository

    Yandjah, L.

    2018-04-03

    Polycrystalline CuIn0.5Ga0.5Te2 films were deposited by flash evaporation from ingot prepared by reacting, in stoichiometric proportions, high purity Cu, In, Ga and Te elements in vacuum sealed quartz . The as-obtained films were characterized by X – ray diffraction (XRD), transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDS). XRD and TEM results showed that the layer has a chalcopyrite-type structure, predominantly oriented along (112) planes, with lattice parameters a = 0.61 nm and c = 1.22 nm. The optical properties in the near - infrared and visible range 600 - 2400 nm have been studied. The analysis of absorption coefficient yielded an energy gap value of 1.27 eV. Photoluminescence analysis of as-grown sample shows two main emission peaks located at 0.87 and 1.19 eV at 4 K.

  12. BiFeO3-doped (Na0.5K0.5NbO3 lead-free piezoelectric ceramics

    Directory of Open Access Journals (Sweden)

    Xueyi Sun et al

    2008-01-01

    Full Text Available Lead-free piezoelectric ceramics (1−x(Na0.5K0.5NbO3-xBiFeO3 (x=0~0.07 were synthesized by the solid-state reaction. Differential scanning calorimetry (DSC measurements revealed that an increase in the amount of BiFeO3 dopant resulted in a decrease in the orthorhombic-tetragonal and tetragonal-cubic phase transition temperature of the material. One percent BiFeO3 additive suppressed grain growth, which not only benefits the sintering of ceramics but also enhances the piezoelectric and ferroelectric properties, where d33=145pC/N, kp=0.31, Qm=80, Pr=11.3 μC cm−2 and Ec=16.5 kV cm−1. As xBF>0.01, both piezoelectric and ferroelectric properties decreased rapidly with an increasing amount of dopant.

  13. Enhancement of the piezoelectric properties of sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) through modification with cobalt

    International Nuclear Information System (INIS)

    Wang Chunming; Wang Jinfeng; Zheng Limei; Zhao Minglei; Wang Chunlei

    2010-01-01

    The dielectric, piezoelectric, and electromechanical properties of B-site cobalt-modified sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) piezoelectric ceramics were investigated. The piezoelectric properties of NLBT ceramics can be enhanced by cobalt modifications. The NLBT ceramics modified with 0.2 wt.% cobalt trioxide (NLBT-C4) possess good piezoelectric properties, with piezoelectric coefficient d 33 of 27 pC/N, electromechanical coupling factors (k p and k t ) of 6.5% and 28.5%, and mechanical quality factor Q m (k p mode) of 3400. The Curie temperature T c of cobalt-modified NLBT ceramics was found to slightly higher than that of pure NLBT ceramics. A large dielectric abnormity in dielectric loss tan δ was observed in NLBT ceramics, which can be significantly suppressed by cobalt modification. Thermal annealing studies presented the cobalt-modified NLBT ceramics possess stable piezoelectric properties.

  14. The effect of K and Na excess on the ferroelectric and piezoelectric properties of K0.5Na0.5NbO3 thin films

    Science.gov (United States)

    Ahn, C. W.; Y Lee, S.; Lee, H. J.; Ullah, A.; Bae, J. S.; Jeong, E. D.; Choi, J. S.; Park, B. H.; Kim, I. W.

    2009-11-01

    We have fabricated K0.5Na0.5NbO3 (KNN) thin films on Pt substrates by a chemical solution deposition method and investigated the effect of K and Na excess (0-30 mol%) on ferroelectric and piezoelectric properties of KNN thin film. It was found that with increasing K and Na excess in a precursor solution from 0 to 30 mol%, the leakage current and ferroelectric properties were strongly affected. KNN thin film synthesized by using 20 mol% K and Na excess precursor solution exhibited a low leakage current density and well saturated ferroelectric P-E hysteresis loops. Moreover, the optimized KNN thin film had good fatigue resistance and a piezoelectric constant of 40 pm V-1, which is comparable to that of polycrystalline PZT thin films.

  15. The effect of K and Na excess on the ferroelectric and piezoelectric properties of K0.5Na0.5NbO3 thin films

    International Nuclear Information System (INIS)

    Ahn, C W; Bae, J S; Jeong, E D; Lee, S Y; Lee, H J; Ullah, A; Kim, I W; Choi, J S; Park, B H

    2009-01-01

    We have fabricated K 0.5 Na 0.5 NbO 3 (KNN) thin films on Pt substrates by a chemical solution deposition method and investigated the effect of K and Na excess (0-30 mol%) on ferroelectric and piezoelectric properties of KNN thin film. It was found that with increasing K and Na excess in a precursor solution from 0 to 30 mol%, the leakage current and ferroelectric properties were strongly affected. KNN thin film synthesized by using 20 mol% K and Na excess precursor solution exhibited a low leakage current density and well saturated ferroelectric P-E hysteresis loops. Moreover, the optimized KNN thin film had good fatigue resistance and a piezoelectric constant of 40 pm V -1 , which is comparable to that of polycrystalline PZT thin films.

  16. Influence of applied electric field annealing on the microwave properties of (Ba0.5Sr0.5)TiO3 thin films

    Science.gov (United States)

    Cho, Kwang-Hwan; Lee, Chil-Hyoung; Kang, Chong-Yun; Yoon, Seok-Jin; Lee, Young-Pak

    2007-04-01

    The effect of heat treatment in electric field on the structure and dielectric properties at microwave range of rf magnetron sputtering derived (Ba0.5Sr0.5)TiO3 thin films have been studied. It has been demonstrated that postannealing in the proper electric field can increase the dielectric constant and the tunability. The increased out-of-plane lattice constant in the electric-annealed films indicated the formation of small polar regions with tetragonal structure, which are responsible for the increased dielectric constant and tunability. It was proposed that the segregation of Ti3+ ions caused by electric annealing could induce the formation of BaTiO3-like regions, which are ferroelectric at room temperature. And in dielectric loss, as the Ti-O bonding lengths increase, the energy scattering on the ferroelectric mode also increases. So, the value of dielectric loss is slightly increased.

  17. Effect of Natural Aging and Cold Working on Microstructures and Mechanical Properties of Al-4.6Cu-0.5Mg-0.5Ag alloy

    Science.gov (United States)

    Chen, Yu-Te; Lee, Sheng-Long; Bor, Hui-Yun; Lin, Jing-Chie

    2013-06-01

    This research investigates the effects of natural aging and cold working prior to artificial aging on microstructures and mechanical properties of Al-4.6Cu-0.5Mg-0.5Ag alloy. Mechanical properties relative to microstructure variations were elucidated by the observations of the optical microscope (OM), differential scanning calorimeter (DSC), electrical conductivity meter (pct IACS), and transmission electron microscopy (TEM). The results showed that natural aging treatment has little noticeable benefit on the quantity of precipitation strengthening phases and mechanical properties, but it increases the precipitation strengthening rate at the initial stage of artificial aging. Cold working brings more lattice defects which suppress Al-Cu (GP zone) and Mg-Ag clustering, and therefore the precipitation of Ω phase decreases. Furthermore, more dislocations are formed, leading to precipitate the more heterogeneous nucleation of θ' phase. The above-mentioned precipitation phenomena and strain hardening effect are more obvious with higher degrees of cold working.

  18. Synthesis and characterization of Sm0.5Ba0.5MnO3-δ as anode materials for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Abdalla, A. M.; Radenahmad, N.; Bakar, M. S. Abu; Petra, Pg M .I.; Azad, A. K.

    2016-01-01

    The material performance is a crucial issue in the current fuel cell technology, and for this reason we present this new series of Samarium family which can be used as electrode giving a high performance in a particular application. Sm 0 . 5 Ba 0 . 5 MnO 3-δ was prepared by solid state reaction method and characterized by using X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Rietveld analysis of XRD data shows that the material has an Orthorhombic crystal structure with cell parameter a = 3.883(1) Å b = 3.8742(5) Å c = 7. 762(4) Å, in the Pmmm space group. TGA analyses shows that the materials is going to decrease by 0.32%. The density of the materials was calculated from structural refinement and found to be 8.372 gm/cm 3 . (paper)

  19. Effect of antimony substitution for niobium on the crystal structure, piezoelectric and dielectric properties of (K0.5Na0.5)NbO3 ceramics

    DEFF Research Database (Denmark)

    Mgbemere, H E; Schneider, G A; Stegk, Tobias

    2010-01-01

    The effect of antimony (Sb) substitution for niobium (Nb) on potassium sodium niobate (KNN) ceramic was investigated with respect to the densification behaviour at different sintering temperatures, microstructure and electrical properties. A small amount of Sb5+ was added while simultaneously...... temperature. The dielectric loss slightly increases with increasing Sb5+ content up to 200°C. There was an improvement in the piezoelectric properties with ≤ 6 mol% Sb content while optimum properties were obtained with 4 mol% (KP = 0.46, Qm = 6.2, NP = 2296)....... lowering the amount of Nb5+ and in this study of the (K0.5Na0.5)(Nb1-xSbx)O3 system, x content was varied from 0 to 14 mol%. Our results show that Sb5+ slightly increased the optimum sintering temperature for KNN but above 8 mol%, its resistivity and piezoelectric properties decreased. As the amount of Sb5...

  20. Tetra­kis(aceto­nitrile)copper(I) hydrogen oxalate–oxalic acid–aceto­nitrile (1/0.5/0.5)

    Science.gov (United States)

    Royappa, A. Timothy; Stepherson, Jacob R.; Vu, Oliver D.; Royappa, Andrew D.; Stern, Charlotte L.; Müller, Peter

    2013-01-01

    In the title compound, [Cu(CH3CN)4](C2HO4)·0.5C2H2O4·0.5CH3CN, the CuI ion is coordinated by the N atoms of four aceto­nitrile ligands in a slightly distorted tetra­hedral environment. The oxalic acid mol­ecule lies across an inversion center. The aceto­nitrile solvent mol­ecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid mol­ecules are linked via O—H⋯O hydrogen bonds, forming chains along [010]. PMID:24098175

  1. Polarization-switching dynamics and microstructures of ferroelectric (Bi0.5Na0.5)TiO3 single crystals

    Science.gov (United States)

    Yanai, Ken; Onozuka, Hiroaki; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Kurushima, Kousuke; Mori, Shigeo

    2013-04-01

    Single crystals of ferroelectric (Bi0.5Na0.5)TiO3 were successfully grown by using the top-seeded solution growth method at a high oxygen pressure of 0.9 MPa and their polarization switching dynamics along the c direction and their domain structures were investigated. Piezoelectric force microscope (PFM) observations show that BNT crystals poled along the c direction. had 71-degree domains in which the spontaneous polarization ( P s ) vector was opposite to the direction of the poling electric field. Synchrotron-radiation single-crystal X-ray diffraction analyses and PFM observations revealed that the polarization switching in the BNT crystals along the c direction was achieved by a 71-degree rotation of the P s vector.

  2. Ferrites Ni0,5Zn0,5Fe2O4 doped with samarium: structural analysis, morphological and electromagnetic

    International Nuclear Information System (INIS)

    Costa, A.C.F.M.; Diniz, A.P.; Viana, K.M.S.; Cornejo, D.R.; Kiminami, R.H.G.A.

    2010-01-01

    This paper proposes to investigate the sintering at 1200 deg C/2h of Ni 0.5 Zn 0.5 Fe 2-x Sm x O 4 ferrite doped with 0.05; 0.075 e 0.1 mol of Sm synthesized by combustion reaction to evaluate the performance materials as absorbers of electromagnetic radiation. The influence of the concentration of samarium on the structure, morphology and electromagnetic properties of ferrites was studied. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic measurements and reflectivity measurements in the frequency range between 8-12 GHz. The results showed that increasing the concentration of samarium caused a decrease in particle size of the samples, encouraging, therefore, to obtain materials with better values of magnetization and reflectivity, allowing for use as absorbers in narrow-band frequency between 9-10 GHz. (author)

  3. Magnetocaloric effect of polycrystalline Sm0.5Ca0.5MnO3 compound: Investigation of low temperature magnetic state

    Science.gov (United States)

    Das, Kalipada; Banu, Nasrin; Das, I.; Dev, B. N.

    2018-06-01

    An attempt has been made to probe low temperature magnetic state of the polycrystalline Sm0.5Ca0.5MnO3 compound via magnetization and magnetocaloric studies. In the context of the earlier debatable reports on the above mentioned compound between the existence of glassy magnetic state and small ferromagnetic domains from the 'ac' susceptibility measurements, our experimental observation from magnetocaloric effect study clearly indicates the existence of ferromagnetic droplets along with certain amount of superparamagnetic component at low temperature (magnetization (even at H = 0.01 T) data do not exhibit the spin freezing nature at the low temperature which is almost a generic tendency of glassy magnetic state. Our study also highlights the competence of magnetocaloric effect as a tool to distinguish between different magnetic states of a compound.

  4. Magnetization, magnetotransport and electron magnetic resonance studies of nanoparticles and nanowires of Pr0.5Sr0.5MnO3

    International Nuclear Information System (INIS)

    Rao, S S; Bhat, S V

    2009-01-01

    In this paper, we present the preparation and characterization of nanoparticles and nanowires of Pr 0.5 Sr 0.5 MnO 3 (PSMO). The main results of this investigation are as follows: (a) a comparison with the properties of the bulk material shows that the ferromagnetic (FM) transition at 270 K remains unaffected but the anti-ferromagnetic (AFM) transition at T N = 150 K disappears in the nanoparticles, (b) the size induced ground state magnetic phase (below 150 K) is predominantly FM, coexisting with a residual AFM phase, and (c) the temperature dependence of magnetic anisotropy shows complex behaviour, being higher in the nanoparticles at high temperatures and lower at moderately lower temperatures in comparison with the bulk. The results obtained from the extensive magnetization, magnetotransport and electron magnetic resonance studies made on various samples are presented and discussed in detail.

  5. Magnetic properties and magnetocaloric effect of MnFeP0.5Ge0.5-xSix compounds

    International Nuclear Information System (INIS)

    Song, L.; Wang, G.F.; Ou, Z.Q.; Haschaolu, O.; Tegus, O.; Brueck, E.; Buschow, K.H.J.

    2009-01-01

    We have studied the magnetic properties and magnetic-entropy changes of the MnFeP 0.5 Ge 0.5-x Si x compounds with x = 0.1, 0.2, 0.3, 0.4 and 0.45. X-ray diffraction shows that the compounds crystallize in the Fe 2 P-type hexagonal structure. The lattice parameter a and the Curie temperature decreases with increasing x. The maximal magnetic-entropy changes for x = 0.4 and 0.45 derived from the magnetization data are about 6.0 J/kg K and 5.8 J/kg K, respectively, for a field change from 0 to 1.5 T

  6. Synthesis and characterization of Ba_0_._5Pb_0_._5TiO_3 perovskite - type thin films deposited by spin coating at low temperatures

    International Nuclear Information System (INIS)

    Wermuth, T.B.; Wiederkehr, N.A.; Alves, A.K.; Bergmann, C.P.

    2014-01-01

    In this paper we present a non-aqueous sol-gel route for the obtention of solid compounds and thin films of oxide type- perovskite ABO_3, such as Ba_0_._5 Pb_0_._5 TiO_3, synthesized by sol - gel route with subsequent heat treatment. The solid compounds were characterized by X-ray diffraction (XRD) techniques and thermal analysis (TGA / DTA). The thin film was obtained by using spin-coating techniques at low temperatures onto commercial substrates of polymethylmethacrylate (PMMA) and characterized by contact angle, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that the films present microstructures and roughness directly related to annealing temperatures, characterized by the formation of crystalline nanostructures with surface regularity and transparency. (author)

  7. Luminescence and magnetic behaviour of almond like (Na0.5La0.5)MoO4:RE3+ (RE = Eu, Tb, Dy) nanostructures

    International Nuclear Information System (INIS)

    Krishnan, Rajagopalan; Thirumalai, Jagannathan; Thomas, Sabu; Gowri, Mahasampath

    2014-01-01

    Graphical abstract: Monodispersed almond-like (Na 0.5 La 0.5 )MoO 4 :RE 3+ nanostructures synthesized by employing ethylene-diamine tetra acetic acid (EDTA) using hydrothermal route at 200 °C for 24 h. These nanoparticles were found to be novel bi-functional candidates suitable for high-quality luminescence and magnetic applications. - Highlights: • Almond like structures of (Na 0.5 La 0.5 )MoO 4 :RE 3+ were synthesized by hydrothermal method. • Time dependent self-assembly could be the dominant process for the formation of 3D networks. • Luminescence properties of nanosamples were studied in comparison with bulk sample. • Room temperature magnetic properties of bulk and nanophosphors were investigated. - Abstract: Tetragonal phase (Na 0.5 La 0.5 )MoO 4 :RE 3+ (RE = Eu, Tb, Dy) with almond like hierarchical structures assembled from nanosheets building blocks were successfully synthesized by employing disodium ethylenediaminetetraacetic acid (Na 2 EDTA) using hydrothermal route at 200 °C for 24 h. Field emission scanning electron microscope, transmission electron microscope, and X-ray diffraction patterns were used to characterize the morphology, size, and crystal structure with good resolution. The sequestering agent EDTA acts as quadridentate ligand coordinated with metal ions [Na + , La 3+ /RE 3+ ] facilitating the formation of self-organized 3D networks. The growth mechanism for the formation of almond like nanostructures is explicated in four paths: dissolution, adsorption, in situ transformation in acidic and basic media and the effective collision. Photoluminescence excitation and emission spectra reveals a spectral blue shift which was observed in the nanosamples towards shorter wavelengths compared with the bulk sample. Upon UV irradiation, both bulk and nanostructure show strong luminescence in the red region due to the 5 D 0 → 7 F 2 transition in Eu 3+ . Also, Tb 3+ and Dy 3+ doped (Na 0.5 La 0.5 )MoO 4 phosphor exhibit green and yellow

  8. Thermoelectric properties of TiNiSn and Zr0.5Hf0.5NiSn thin films and superlattices with reduced thermal conductivities

    International Nuclear Information System (INIS)

    Jaeger, Tino

    2013-01-01

    Rising energy costs and enhanced CO 2 emission have moved research about thermoelectric (TE) materials into focus. The suitability of a material for usage in TE devices depends on the figure of merit ZT and is equal to α 2 σTκ -1 including Seebeck coefficient α, conductivity σ, temperature T and thermal conductivity κ. Without affecting the power factor α 2 σ, using nanostructuring, ZT should here be increased by a depressed thermal conductivity. As half-Heusler (HH) bulk materials, the TE properties of TiNiSn and Zr 0.5 Hf 0.5 NiSn have been extensively studied. Here, semiconducting TiNiSn and Zr 0.5 Hf 0.5 NiSn thin films were fabricated for the first time by dc magnetron sputtering. On MgO (100) substrates, strongly textured polycrystalline films were obtained at substrate temperatures of about 450 C. The film consisted of grains with an elongation perpendicular to the surface of 55 nm. These generated rocking curves with FWHMs of less than 1 . Structural analyses were performed by X ray diffraction (XRD). Having deposition rates of about 1 nms -1 within shortest time also films in the order of microns were fabricated. For TiNiSn the highest in-plane power factor of about 0.4 mWK -2 m -1 was measured at about 550 K. In addition, at room temperature a cross-plane thermal conductivity of 2.8 Wm -1 K -1 was observed by the differential 3ω method. Because the reduction of thermal conductivity by mass fluctuation is well-known and interface scattering of phonons is expected, superlattices (SL) were fabricated. Therefore, TiNiSn and Zr 0.5 Hf 0.5 NiSn were successively deposited. While the sputter cathodes were continuously running, for fabrication of SLs the substrates were moved from one to another. The high crystal quality of the SLs and the sharp interfaces were proven by satellite peaks (XRD) and Scanning Transmission Electron Microscopy (STEM). For a SL with a periodicity of 21 nm (TiNiSn and Zr 0.5 Hf 0.5 NiSn each 15 nm) at a temperature of 550 K an

  9. Formation of Ruddlesden-Popper Faults and Their Effect on the Magnetic Properties in Pr0.5Sr0.5CoO3 Thin Films.

    Science.gov (United States)

    Jing, Hong-Mei; Cheng, Sheng; Mi, Shao-Bo; Lu, Lu; Liu, Ming; Cheng, Shao-Dong; Jia, Chun-Lin

    2018-01-10

    Epitaxial Pr 0.5 Sr 0.5 CoO 3 thin films have been grown on single-crystalline (La 0.289 Sr 0.712 )(Al 0.633 Ta 0.356 )O 3 (001) substrates by the pulsed laser deposition technique. The magnetic properties and microstructure of these films are investigated. It is found that Ruddlesden-Popper faults (RP faults) can be introduced in the films by changing the laser repetition rate. The segregation of Pr at the RP faults is characterized by atomic-resolution chemical mapping. The formation of the RP faults not only contributes to the epitaxial strain relaxation but also significantly decreases the ferromagnetic long-range order of the films, resulting in lower magnetizations than those of the fault-free films. Our results provide a strategy for tuning the magnetic properties of cobalt-based perovskite films by modifying the microstructure through the film growth process.

  10. The effect of post-annealing on the structure and magnetotransport properties of Pr0.5Sr0.5MnO3 thin film

    Directory of Open Access Journals (Sweden)

    Liping Chen

    2017-05-01

    Full Text Available Pr0.5Sr0.5MnO3 (PSMO thin film is epitaxially grown on (001-oriented LaAlO3 single-crystal substrate using pulsed laser deposition (PLD. It is found that the as-grown PSMO film shows compressive strain in plane and tensile strain out of the plane. Upon annealing at 900°C in the air, the strain is significantly relaxed. The paramagnetic to ferromagnetic phase transition temperature TC shifts from 200 K to 220 K, and the antiferromagnetic insulating phase is suppressed in the phase separated state at low temperature. In addition, the magnetoresistance (MR is found to increase around the ferromagnetic transition temperature, whereas it decreases from 99% to 60% at low temperature of 20 K.

  11. The effect of post-annealing on the structure and magnetotransport properties of Pr0.5Sr0.5MnO3 thin film

    Science.gov (United States)

    Chen, Liping; Zeng, Jiali; Li, Miao; Tang, Zhenhua; Gao, Ju

    2017-05-01

    Pr0.5Sr0.5MnO3 (PSMO) thin film is epitaxially grown on (001)-oriented LaAlO3 single-crystal substrate using pulsed laser deposition (PLD). It is found that the as-grown PSMO film shows compressive strain in plane and tensile strain out of the plane. Upon annealing at 900°C in the air, the strain is significantly relaxed. The paramagnetic to ferromagnetic phase transition temperature TC shifts from 200 K to 220 K, and the antiferromagnetic insulating phase is suppressed in the phase separated state at low temperature. In addition, the magnetoresistance (MR) is found to increase around the ferromagnetic transition temperature, whereas it decreases from 99% to 60% at low temperature of 20 K.

  12. Coherent nanoscale islands on La0.5Ca0.5MnO3 thin films and the enhancement of magnetoresistance

    International Nuclear Information System (INIS)

    Gong, W. Z.; Zhao, B. R.; Cai, C.; Lin, Y.

    2001-01-01

    A low cost reproducible fabrication process has been developed to prepare La 0.5 Ca 0.5 MnO 3 (LCMO) films with well distributed uniform nanoscale dots using pulsed-laser deposition. It was found that the growth of the dots was closely related to the strain in the film during the growth process. The diameter and density of dots could be controlled within the range of 30--120 nm and 2 x 10 8 --2 x 10 9 /cm 2 , respectively. The magnetoresistance effect of such LCMO films is also enhanced, which may be caused by the spin-dependent scattering of carriers due to the existence of the dots. Copyright 2001 American Institute of Physics

  13. Suppression of structural and magnetotransport transitions in compressed Pr0.5Sr0.5MnO3 thin films resulting in colossal magnetoresistance effect

    International Nuclear Information System (INIS)

    Mercey, B.; Hervieu, M.; Prellier, W.; Wolfman, J.; Simon, C.; Raveau, B.

    2001-01-01

    Thin films of Pr 0.5 Sr 0.5 MnO 3 have been deposited on [100]-LaAlO 3 using laser ablation. In contrast to the bulk compounds, such films do not exhibit any structural and magnetotransport transitions versus temperature; more particularly the A-type antiferromagnetic phase with the Fmmm structure which exists in the bulk below T N =135K is suppressed, and the film is an insulator in the absence of a magnetic field. However a colossal magnetoresistance effect is observed, with resistance ratios much larger than in the bulk. These differences with respect to the bulk, are explained by the presence of substrate-induced strains. [copyright] 2001 American Institute of Physics

  14. Large anisotropy in colossal magnetoresistance of charge orbital ordered epitaxial Sm(0.5)Ca(0.5)MnO(3) films.

    Science.gov (United States)

    Chen, Y Z; Sun, J R; Zhao, J L; Wang, J; Shen, B G; Pryds, N

    2009-11-04

    We investigated the structure and magnetotransport properties of Sm(0.5)Ca(0.5)MnO(3) (SCMO) films epitaxially grown on (011)-oriented SrTiO(3) substrates, which exhibited clear charge/orbital ordering transition. A significant anisotropy of ∼1000 in the colossal magnetoresistance (CMR) effect was observed in the films with a thickness between 50 and 80 nm, which was distinctly different from the basically isotropic CMR effect in bulk SCMO. The large anisotropy in the CMR can be ascribed to the intrinsic asymmetric strain in the film, which plays an important role in tuning the spin-orbit coupling in manganite films. The origin of the peculiar CMR effect is discussed.

  15. Ferro and antiferro orbital ordering in Fe{sub 0.5}Mn{sub 0.5}V{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Dibyendu, E-mail: dibyendu@phy.iitkgp.ernet.in; Taraphder, A. [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Maitra, T. [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India)

    2016-05-23

    Using density functional theory calculations, we have investigated the orbital ordering in Fe{sub 0.5}Mn{sub 0.5}V{sub 2}O{sub 4} where Fe and V sites are orbitally active. Our first principles study within GGA+U and GGA+U+SO shows ferro-orbital ordering of d{sub x2−y2} orbital at all Fe sites, whereas A-type antiferro-orbital ordering at V sites where one 3d electron occupies d{sub xy} orbital at every V site and another electron occupies either 1/√2 (d{sub xz} + d{sub yz}) or 1/√2 (d{sub xz} - d{sub yz}) orbital alternatively along c axis. Insulating nature and the orbital ordering of this compound are found to be correlation driven while the effect of spin-orbit interaction on orbital ordering is not significant.

  16. Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La{sub 0.5}Ca{sub 0.5}MnO₃ nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Iniama, G.; Ita, B. I. [Department of Pure and Applied Chemistry, University of Calabar, Calabar (Nigeria); Presa, P. de la, E-mail: pmpresa@ucm.es; Hernando, A. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Físicas, Dpto. Física de Materiales, Univ. Complutense de Madrid, 28040 Madrid (Spain); Alonso, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Instituto de Ciencia de Materiales, CSIC, 28049-Madrid (Spain); Multigner, M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Cortés-Gil, R.; Ruiz-González, M. L. [Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain); Gonzalez-Calbet, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain)

    2014-09-21

    In this paper, the physical properties of half-doped manganite La{sub 0.5}Ca{sub 0.5}MnO₃ with crystallite sizes ranging from 15 to 40 nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15 nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22 nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15 nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.

  17. Observation of indium ion migration-induced resistive switching in Al/Mg_0_._5Ca_0_._5TiO_3/ITO

    International Nuclear Information System (INIS)

    Lin, Zong-Han; Wang, Yeong-Her

    2016-01-01

    Understanding switching mechanisms is very important for resistive random access memory (RRAM) applications. This letter reports an investigation of Al/Mg_0_._5Ca_0_._5TiO_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_2O_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"3"+ ion migration is proposed. In"3"+ ion migration forms/ruptures the conductive filaments and sets/resets the RRAM device.

  18. Effect of deposition temperature & oxygen pressure on mechanical properties of (0.5) BZT-(0.5)BCT ceramic thin films

    Science.gov (United States)

    Sailaja, P.; Kumar, N. Pavan; Rajalakshmi, R.; Kumar, R. Arockia; Ponpandian, N.; Prabahar, K.; Srinivas, A.

    2018-05-01

    Lead free ferroelectric thin films of {(0.5) BZT-(0.5) BCT} (termed as BCZT) were deposited on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition at four deposition temperatures 600, 650, 700, 750°C and at two oxygen pressures viz. 75mtorr and 100 mtorr using BCZT ceramic target (prepared by solid state sintering method). The effect of deposition temperature and oxygen pressure on the structure, microstructure and mechanical properties of BCZT films were studied. X-ray diffraction patterns of deposited films confirm tetragonal crystal symmetry and the crystallinity of the films increases with increasing deposition temperature. Variation in BCZT grain growth was observed when the films are deposited at different temperatures andoxygen pressures respectively. The mechanical properties viz. hardness and elastic modulus were also found to be high with increase in the deposition temperature and oxygen pressure. The results will be discussed.

  19. Electric-pulse-induced resistance switching effect in the bulk of La0.5Ca0.5MnO3 ceramics

    Directory of Open Access Journals (Sweden)

    M. L. Wu

    2014-04-01

    Full Text Available In the majority of contributions, the electrical–pulse-induced resistance (EPIR switching effect of perovskite manganites is thought to originate from the extrinsic interfacial Schottky barrier between the metal electrode and the surface of sample. In this work, La0.5Ca0.5MnO3 (LCMO ceramic samples were synthesized by solid state reaction and the transport properties, especially, the EPIR effect and memristor behavior were investigated under 4-wire method using silver-glue as electrodes. Although the I-V characteristic of LCMO shows an ohmic linearity under the 4-wire mode at room temperature, a stable and remarkable EPIR can still be observed when the pulse voltage is more than a critical value. This bulk EPIR effect is novel for rare - earth doped manganites.

  20. Topology and temperature dependence of the diffuse X-ray scattering in Na0.5Bi0.5TiO3 ferroelectric single crystals.

    Science.gov (United States)

    Gorfman, Semën; Keeble, Dean S; Bombardi, Alessandro; Thomas, Pam A

    2015-10-01

    The results of high-resolution measurements of the diffuse X-ray scattering produced by a perovskite-based Na 0.5 Bi 0.5 TiO 3 ferroelectric single crystal between 40 and 620 K are reported. The study was designed as an attempt to resolve numerous controversies regarding the average structure of Na 0.5 Bi 0.5 TiO 3 , such as the mechanism of the phase transitions between the tetragonal, P 4 bm , and rhombohedral | monoclinic, R 3 c  |  Cc , space groups and the correlation between structural changes and macroscopic physical properties. The starting point was to search for any transformations of structural disorder in the temperature range of thermal depoling (420-480 K), where the average structure is known to remain unchanged. The intensity distribution around the {032} pseudocubic reflection was collected using a PILATUS 100K detector at the I16 beamline of the Diamond Light Source (UK). The data revealed previously unknown features of the diffuse scattering, including a system of dual asymmetric L-shaped diffuse scattering streaks. The topology, temperature dependence, and relationship between Bragg and diffuse intensities suggest the presence of complex microstructure in the low-temperature R 3 c  |  Cc phase. This microstructure may be formed by the persistence of the higher-temperature P 4 bm phase, built into a lower-temperature R 3 c  |  Cc matrix, accompanied by the related long-range strain fields. Finally, it is shown that a correlation between the temperature dependence of the X-ray scattering features and the temperature regime of thermal depoling is present.

  1. Magnetic and electrical transport properties of La0.5A0.5CoO3 nanoparticles (A = Sr, Ca, and Ba)

    International Nuclear Information System (INIS)

    Roy, B.; Das, S.

    2011-01-01

    Research highlights: → La 0.5 A 0.5 CoO 3 (A = Sr, Ca, and Ba) nanoparticles prepared by sol-gel technique. → Size-induced metal-insulator transition in Sr- and Ba-doped samples. → Broad paramagnetic to ferromagnetic transition with large magnetic irreversibility. → Co 3+ ions in intermediate and Co 4+ in a mixture of intermediate and high spin states. → ac magnetization suggests magnetic cluster glass nature of the samples. - Abstract: We have investigated the effect of particle size on the electrical transport and magnetic properties of La 0.5 A 0.5 CoO 3 (A = Sr, Ca, and Ba) nanoparticles synthesized by sol-gel technique. A size-induced metal to insulator transition is observed in the resistivity behaviour of Sr- and Ba-doped samples as the dimension changes from higher to lower ones. The magnetoresistance exhibits almost linear behaviour throughout the studied field range. The zero-field-cooled (ZFC) and field-cooled (FC) magnetizations display a broad paramagnetic to ferromagnetic transition at T C with a large magnetic irreversibility. The magnetization results indicate that Co 3+ ions are in the intermediate spin state but Co 4+ ions stay in a mixture of intermediate and high spin states. The observed frequency dependent shoulder in the in-phase and the peak in the out of phase component of the ac susceptibility indicate the glassy nature of the samples. The analysis of the ac magnetization results suggests that the magnetic behaviour is consistent with the cluster glass model.

  2. Synthesis and characterization of Na(Gd0.5Lu0.5)F4: Nd3+,a core-shell free multifunctional contrast agent.

    Science.gov (United States)

    Mimun, L Christopher; Ajithkumar, G; Rightsell, Chris; Langloss, Brian W; Therien, Michael J; Sardar, Dhiraj K

    2017-02-25

    Compared to conventional core-shell structures, core-shell free nanoparticles with multiple functionalities offer several advantages such as minimal synthetic complexity and low production cost. In this paper, we present the synthesis and characterization of Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 as a core-shell free nanoparticle system with three functionalities. Nanocrystals with 20 nm diameter, high crystallinity and a narrow particle size distributions were synthesized by the solvothermal method and characterized by various analytical techniques to understand their phase and morphology. Fluorescence characteristics under near infrared (NIR) excitation at 808 nm as well as X-ray excitation were studied to explore their potential in NIR optical and X-ray imaging. At 1.0 mol% Nd concentration, we observed a quantum yield of 25% at 1064 nm emission with 13 W/cm 2 excitation power density which is sufficiently enough for imaging applications. Under 130 kVp (5 mA) power of X-ray excitation, Nd 3+ doped Na(Gd 0.5 Lu 0.5 )F 4 shows the characteristic emission bands of Gd 3+ and Nd 3+ with the strongest emission peak at 1064 nm due to Nd 3+ . Furthermore, magnetization measurements show that the nanocrystals are paramagnetic in nature with a calculated magnetic moment per particle of ~570 μB at 2T. These preliminary results support the suitability of the present nanophosphor as a multimodal contrast agent with three imaging features viz. optical, magnetic and X-ray.

  3. Phase transformation and impedance spectroscopic study of Ba substituted Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Rekha [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar, 125001, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar, 125001, Haryana (India); Agarwal, Ashish; Sanghi, Sujata [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar, 125001, Haryana (India); Sindhu, Monica [Department of Physics, MKJK College, Rohtak, 124001, Haryana (India); Ahlawat, Navneet [Matu Ram Institute of Engineering and Management, Rohtak, 124001, Haryana (India)

    2016-08-15

    (Na{sub 0.5}Bi{sub 0.5}){sub 1−x}Ba{sub x}TiO{sub 3} (x = 0.05, 0.1 and 0.15) ceramics abbreviated as (NBBT1, NBBT2 and NBBT3) are fabricated by conventional ceramic fabrication technique. The analysis of X-ray diffraction pattern of the prepared ceramic performed by Rietveld refinement indicate that crystal structure is rhombohedral for NBBT1, tetragonal for NBBT3 and a phase boundary occurs for NBBT2. Impedance spectroscopy has been employed to study the electrical properties of these ceramics in the frequency range of 10 Hz to 5 MHz and in a temperature range of 303 K–723 K. Frequency and temperature dependent electrical data is analyzed in the framework of conductivity, impedance and electric modulus formalisms. Conductivity spectrum obeys double power law for NBBT1, which is evidenced from two different dispersion regions. While for NBBT2 and NBBT3 only single power law is observed. Relaxation frequency for impedance is found to increase with temperature and obeys Arrhenius relationship with activation energy ≈0.764, 0.527 and 0.471 eV for NBBT1, NBBT2 and NBBT3 respectively. Variation of dielectric constant and tanδ with frequency at different temperatures was analyzed with the help of Maxwell–Wagner and Koop's phenomenogical theory. The presence of peaks in plots showing frequency dependence of tanδ for NBBT2 and NBBT3 indicates relaxor behavior of these compositions. - Highlights: • (Na{sub 0.5}Bi{sub 0.5}){sub 1−x}Ba{sub x}TiO{sub 3} (x = 0.05, 0.1, 0.15) ceramics have been synthesized. • There is change in crystal structure with Ba doping. • NBBT2 and NBBT3 show relaxor behavior.

  4. Eu3+-doped (Y0.5La0.5)2O3: new nanophosphor with the bixbyite cubic structure

    Science.gov (United States)

    Đorđević, Vesna; Nikolić, Marko G.; Bartova, Barbora; Krsmanović, Radenka M.; Antić, Željka; Dramićanin, Miroslav D.

    2013-01-01

    New red sesquioxide phosphor, Eu3+-doped (Y0.5La0.5)2O3, was synthesized in the form of nanocrystalline powder with excellent structural ordering in cubic bixbyite-type, and with nanoparticle sizes ranging between 10 and 20 nm. Photoluminescence measurements show strong, Eu3+ characteristic, red emission ( x = 0.66 and y = 0.34 CIE color coordinates) with an average 5D0 emission lifetime of about 1.3 ms. Maximum splitting of the 7F1 manifold of the Eu3+ ion emission behaves in a way directly proportional to the crystal field strength parameter, and experimental results show perfect agreement with theoretical values for pure cubic sesquioxides. This could be used as an indicator of complete dissolution of Y2O3 and La2O3, showing that (Y0.5La0.5)2O3:Eu3+ behaves as a new bixbyite structure oxide, M2O3, where M acts as an ion having average ionic radius of constituting Y3+ and La3+. Emission properties of this new phosphor were documented with detailed assignments of Eu3+ energy levels at 10 K and at room temperature. Second order crystal field parameters were found to be B 20 = -66 cm-1 and B 22 = -665 cm-1 at 10 K and B 20 = -78 cm-1 and B 22 = -602 cm-1 at room temperature, while for the crystal field strength the value of 1495 cm-1 was calculated at 10 K and 1355 cm-1 at room temperature.

  5. Temperature dependence of domain structure of sintered SmCo5 and Smsub(0,5)Prsub(0,5)Co5 permanent magnets

    International Nuclear Information System (INIS)

    Puzanova, T.Z.; Shur, Ya.S.

    1977-01-01

    The Kerr magneto-optical effect has been used to study the domain structure morphology changes in caked SmCo 5 and Smsub(0,5)Prsub(o,5)So 5 alloy magnets at elevated temperatures in the range from 20 to 180 deg C and after protracted air annealing at temperatures from 130 to 180 deg C. The relation between the domain structure behaviour and temperature-dependent variations of magnetic properties is discussed

  6. Effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mansouri, M., E-mail: mansourimoufida23@yahoo.fr [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Omrani, H. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Cheikhrouhou-Koubaa, W. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Centre de Recherche en Informatique, Multimédia et Traitement Numérique des Données, BP 275, Sakiet Ezzit, 3021 Sfax (Tunisia); Koubaa, M. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Madouri, A. [Laboratoire de Photonique et Nanostructure, LPN-CNRS, Route de Nozay, 91460 Marcoussis (France); Cheikhrouhou, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia)

    2016-03-01

    We report the effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3} (x=0.05; 0.1). Our samples were elaborated using the conventional solid state reaction method at high temperatures. X-Ray powder diffraction at room temperature indicates that our samples crystallize in the orthorhombic structure with Pbnm space group. Magnetic measurements reveal a paramagnetic-ferromagnetic transition with decreasing temperature. Magnetocaloric studies show that the maximum of the magnetic entropy change and the relative cooling power (RCP) are found to be 2.42 J Kg{sup −1} K{sup −1} and 162.75 J Kg{sup −1} for x=0.05 and 3.12 J Kg{sup −1} K{sup −1} and 221.31 J Kg{sup −1} for x=0.1 under a field change of 5 T. - Highlights: • The La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3}(x=0.05 and x=0.1) compounds were synthesized using conventional solid state reaction method. • T{sub C} increases with V content from 187 K for x=0.05 to 263 K for x=0.1 • Large magnetocaloric effect is reported based on second order phase transition. • Noticeable |∆S{sub M}| at 5 T field makes the system useful for magnetic refrigeration.

  7. Colossal thermoelectric power in charge ordered lanthanum calcium manganites (La{sub 0.5}Ca{sub 0.5}MnO{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Joy, Lija K.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India); Shanmukharao Samatham, S.; Ganesan, V. [Low temperature division, UGC-DAE Consortium for Scientific Research, Indore (India); Thomas, Senoy [Material Science and Technology Division, National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram–695019 (India); Al-Harthi, Salim [Department of Physics, Sultan Qaboos University, Muscat PC 123, Sultanate of Oman (Oman); Liebig, A.; Albrecht, M. [Institute of Physics, University of Augsburg, Augsburg 86135 (Germany)

    2014-12-07

    Lanthanum calcium manganites (La{sub 0.5}Ca{sub 0.5}MnO{sub 3}) with a composition close to charge ordering, synthesized by high energy ball milling, was found to exhibit colossal thermoelectric power. Thermoelectric power (TEP) data was systematically analyzed by dividing the entire temperature range (5 K–300 K) into three different regimes to explore different scattering mechanisms involved. Mandal's model has been applied to explain TEP data in the region below the Curie temperature (T{sub C}). It has been found that the variation of thermoelectric power with temperature is pronounced when the system enters the charge ordered region at T < 200 K. For temperatures lower than 120 K, due to the co-existence of charge ordered state with a spin-glass state, the variation of thermoelectric power is maximum and exhibited a peak value of −80 mV/K at 58 K. This has been explained by incorporating Kondo properties of the spin-glass along with magnon scattering. FC-ZFC magnetization measurements indicate the existence of a glassy state in the region corresponding to a maximum value of thermoelectric power. Phonon drag contribution instead of spin-glass contribution is taken into account to explain TEP in the region 120 K < T < T{sub C}. Mott's polaronic contribution of charge carriers are considered to interpret TEP in the high temperature region (T > T{sub C}). The optimal Mn{sup 4+}-Mn{sup 3+} concentration in charge ordered La{sub 0.5}Ca{sub 0.5}MnO{sub 3} was examined by X-ray Photoelectron Spectroscopy analysis which confirms the charge ordered nature of this compound.

  8. Phosphate removal from aqueous solutions using polyaniline/ Ni 0.5 Zn 0.5 Fe 2 O 4 magnetic nanocomposite

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Tarmahi

    2017-05-01

    Full Text Available Background: Phosphorus is an indispensable element for the growth of animals and plants. There are several environmental problems related to phosphate; therefore, the technical and economic methods of removing phosphate are of great importance. This study evaluated the efficiency of polyaniline/ Ni0.5Zn0.5Fe2O4 magnetic nanocomposite in removing phosphate from aqueous environments. Methods: The adsorbent was characterized by several methods, including X-ray diffraction (XRD, scanning electron microscopy (SEM, vibrating sample magnetometer (VSM, and Fourier transform infrared (FT-IR spectroscopy. Then, the potential of the adsorbentto adsorb phosphate was investigated. The effects of the parameters of contact time (5-60 minutes, pH (3-9, adsorbent dosage (0.05-0.6 g, and initial phosphate concentration (2-100 mg/L on the phosphate removal yield were studied. All phosphate ion concentrations were measured using the ammonium molybdate spectrophotometric method. Results: The results showed that a time of 30 minutes, pH of 5, and adsorbent dose of 0.4 g were the optimum conditions for phosphate removal through adsorption. Increasing the initial concentration of phosphate from 2 to 100 mg/L decreased the removal efficiency from 90.3% to 32%. The experimental data was fitted well with the Freundlich isotherm model (R2 = 0.997. Conclusion: Polyaniline/Ni0.5Zn0.5Fe2O4 magnetic nanocomposite removes phosphate from aqueous solutions with a simple and environmentally benign procedure. The maximum adsorption capacity based on Langmuir isotherm (R2 = 0.931 is 85.4 mg/g. This magnetic nanocomposite is applicable in managing water resource pollution caused by phosphate ions.

  9. Frequency effects on charge ordering in Y{sub 0.5}Ca{sub 0.5}MnO{sub 3} by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sarwar, Tuba, E-mail: sarwartuba@gmail.com [EMMG, Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); DPAM, PIEAS, P. O. Nilore, Islamabad (Pakistan); Qamar, Afzaal [Queensland Micro-Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Nadeem, Muhammad [EMMG, Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan)

    2015-02-01

    In this work, structural and electrical properties of Y{sub 0.5}Ca{sub 0.5}MnO{sub 3} are investigated by employing X-ray diffraction and impedance spectroscopy, respectively. Applied ac electric field showed the charge ordering transition temperature around 265 K and below this temperature the heteromorphic behavior of the sample is discussed in the proximity of T{sub CO}. With frequency effects the volume of robust charge orbital ordering (COO) domains diminishes due to different competing phases along with Jahn Teller distortions. Comprehensive melting and collapse of charge orbital ordering occurs below T{sub N}(125 K), where a colossal drop in the value of impedance is observed. The change in profile of modulus plane plots determines the spreading of relaxation time of intermingled phases. Hopping mechanism is elaborated in terms of strong electron phonon coupling. Variable range hopping model and Arrhenius model are used to discuss the short and long range hopping between Mn{sup 3+} and Mn{sup 4+} channels assessing the activation energy E{sub a}. - Highlights: • Present study contains a detailed investigation over the electrical and structural properties of Y{sub 0.5}Ca{sub 0.5}MnO{sub 3} especially its behavior across the charge ordering transition. • Impedance measurements illustrate the comprehensive melting and collapse of robust charge orbital ordering with colossal drop in impedance. • In T{sub N}

  10. A broadband-sensitive upconverter La(Ga0.5Sc0.5)O3:Er,Ni,Nb for crystalline silicon solar cells

    International Nuclear Information System (INIS)

    Takeda, Yasuhiko; Mizuno, Shintaro; Luitel, Hom Nath; Tani, Toshihiko

    2016-01-01

    We have developed an upconverter that significantly broadens the sensitive range, to overcome the shortcoming that conventional Er 3+ -doped upconverters used for crystalline silicon solar cells can utilize only a small portion of the solar spectrum at around 1.55 μm. We have designed the combination of the sensitizers and host material to utilize photons not absorbed by silicon or Er 3+ ions. Ni 2+ ions have been selected as the sensitizers that absorb photons in the wavelength range between the silicon absorption edge (1.1 μm) and the Er 3+ absorption band and transfer the energies to the Er 3+ emitters, with La(Ga,Sc)O 3 as the host material. The Ga to Sc ratio has been optimized to tune the location of the Ni 2+ absorption band for sufficient energy transfer. Co-doping with Nb 5+ ions is needed for charge balance to introduce divalent Ni 2+ ions into the trivalent Ga 3+ and Sc 3+ sites. In addition to 1.45–1.58 μm photons directly absorbed by the Er 3+ ions, we have demonstrated upconversion of 1.1–1.35 μm photons in the Ni 2+ absorption band to 0.98 μm photons, using 10% Er, 0.5% Ni, and 0.5% Nb-doped La(Ga 0.5 Sc 0.5 )O 3 . The broadband-sensitive upconverter developed here can improve conversion efficiency of crystalline silicon solar cells more notably than conventional ones

  11. Colossal elastoresistance, electroresistance and magnetoresistance in Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Liping, E-mail: chenliping0003@163.com [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Department of Physics, Hong Kong University, Hong Kong (China); Guo, Xuexiang [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Gao, J. [Department of Physics, Hong Kong University, Hong Kong (China)

    2016-05-01

    Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} thin films on substrates of (001)-oriented LaAlO{sub 3} were epitaxially grown by pulsed laser deposition. It was found that a substrate-induced strain of ~1.3% brings a great resistivity change of ~98% at 25 K. We studied the dependence of resistivity on the applied electric current and magnetic field. In the greatly strained films of 60 nm thickness the electroresistance ER=[ρ(I{sub 1} {sub μA})−ρ(I{sub 1000} {sub μA})]/ρ(I{sub 1} {sub μA}) reaches ~70% at T=25 K, much higher than ER~7% in the strain-relaxed films of 400 nm thickness, implying the strain effect on ER. Also the magnetoresistance of the film falls with strain-relaxation. Therefore the electric properties of the film could be efficiently modified by strain, electric current and magnetic field. All of them may be explained by the effect on the percolative phase separation and competition in the half-doped manganite material. The manganite films located at phase boundary are expected to be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance due to the multiphase coexistence. - Highlights: • The electric current-induced electroresistance (ER) and magnetoresistance (MR)studies on PLD grown Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3}/(001) LaAlO{sub 3} films were found to be greatly sensitive to the film thickness arising from the strain. • It is shown that, 60 nm film exhibit compressive in-plane strain which leads to phase separation and hence colossal MR and ER. • Our results suggest that the manganites located at phase boundary may be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance.

  12. Structure and cation distribution of (Mn0.5Zn0.5)Fe2O4 thin films on SrTiO3(001)

    Science.gov (United States)

    Welke, M.; Brachwitz, K.; Lorenz, M.; Grundmann, M.; Schindler, K.-M.; Chassé, A.; Denecke, R.

    2017-06-01

    A comprehensive study on growth of ferrimagnetic manganese zinc ferrite (Mn0.5Zn0.5Fe2O4) films on single crystalline strontium titanate(001) (SrTiO3) substrates was carried out. Under the optimized conditions, a thin film with a layer thickness of 200 nm was deposited, and the structural properties were investigated. Contrary to data published in literature, no buffer layer was necessary to achieve epitaxial growth of a poorly lattice-matched layer. This was confirmed for Mn0.5Zn0.5Fe2O4(001) on SrTiO3(001) by x-ray diffraction and the adjoined phi scans, which also revealed a lattice compression of 1.2% of the manganese zinc ferrite film in the out-of-plane direction. Using x-ray photoelectron spectroscopy, the near surface stoichiometry of the film could be shown to agree with the intended one within the uncertainty of the method. X-ray absorption spectroscopy showed an electronic structure close to that published for bulk samples. Additional x-ray magnetic circular dichroism investigations were performed to answer detailed structural questions by a comparison of experimental data with the calculated ones. The calculations took into account ion sites (tetrahedral vs. octahedral coordination) as well as the charge of Fe ions (Fe2+ vs. Fe3+). Contrary to the expectation for a perfect normal spinel that only Fe3+ ions are present in octahedral sites, hints regarding the presence of additional Fe2+ in octahedral sites as well as Fe3+ ions in tetrahedral sites have been obtained. Altogether, the layer could be shown to be mostly in a normal spinel configuration.

  13. Formation pathways in the synthesis and properties of (Tl0.5Pb0.5)(Sr0.9Ba0.1)2Ca2Cu3Oz and (Tl0.5Pb0.5)(Sr0.8Ba0.2)2Ca2Cu3Oz-1223 superconductors

    International Nuclear Information System (INIS)

    Auinger, M; Gritzner, G; Bertrand, Ch; Galez, Ph; Soubeyroux, J-L

    2007-01-01

    The formation pathway of (Tl 0.5 Pb 0.5 )(Sr 0.9 Ba 0.1 ) 2 Ca 2 Cu 3 O z and (Tl 0.5 Pb 0.5 )(Sr 0.8 Ba 0.2 ) 2 Ca 2 Cu 3 O z was studied by neutron and x-ray diffraction. The following reaction pathway was proposed: thallium oxide and lead oxide react with Sr-rich (Sr 1-x Ca x )CuO 2 and Ca-rich (Ca x Sr 1-x )O to form Sr 4 Tl 2 O 7 and (Ca x Sr 1-x )PbO 3 , respectively. The thallate and the plumbate compounds then form the (Tl 0.5 Pb 0.5 )-1212 phase starting at a temperature of 600 deg. C. Finally, between 850 and 900 deg. C, the 1223 phase is formed from (Tl 0.5 Pb 0.5 )-1212 (Ca x Sr 1-x ) 2 CuO 3 and CuO. Parallel experiments to fabricate the (Tl, Pb)-1223 superconductor resulted in specimens with critical temperatures of 117.5 K and 116 K, respectively, and transition widths of 2 K. Differences between the pathways for the formation of Pb-doped, Sr-rich and Pb-free, Ba-rich Tl-1223 superconductors are discussed

  14. Structural and magnetic properties of size-controlled Mn0.5Zn0 ...

    Indian Academy of Sciences (India)

    Abstract. Mn0.5Zn0.5Fe2O4 ferrite nanoparticles with tunable Curie temperature and saturation ... netic fluid is synthesized and magnetic characterization is reported. The monolayer ... the synthesis method – largely affects the macroscopic properties, giving rise to a wide variety of ..... available in sample C. TGA technique ...

  15. Stability and oxygen transport property of La0.8Sr0.2Cr0.5Fe0.5O3 -δ

    DEFF Research Database (Denmark)

    He, Wei; Huang, Hua; Chen, Ming

    2014-01-01

    vacancies in the lattice. LSCrF powder exposed to flowing concentrated hydrogen for 30 h was found to decompose partially. The decomposition oxygen partial pressure of LSCrF at 950 °C was estimated to be 6.3 × 10- 28 atm from thermodynamic calculations. The stability of LSCrF under an oxygen chemical......The stability of La0.8Sr0.2Cr0.5Fe 0.5O3 -δ (LSCrF) in reducing atmosphere was investigated by examining the extent of its reaction with hydrogen at elevated temperature. LSCrF powder exposed to diluted hydrogen was found to loss a weight of only ~ 0.5%, corresponding to the formation of oxygen...... potential gradient was also examined by exposing a disk-shaped dense sample to air at one side and to reducing atmosphere (CO) at the other side at elevated temperatures. A thin, porous layer was found to form on the CO side surface. An oxygen permeation flux of 2.5 × 10- 7 mol cm- 2 s- 1 was observed...

  16. University of Chicago School Mathematics Project 6-12 Curriculum. What Works Clearinghouse Intervention Report

    Science.gov (United States)

    What Works Clearinghouse, 2011

    2011-01-01

    The "University of Chicago School Mathematics Project ("UCSMP") 6-12 Curriculum" is a series of yearlong courses--(1) Transition Mathematics; (2) Algebra; (3) Geometry; (4) Advanced Algebra; (5) Functions, Statistics, and Trigonometry; and (6) Precalculus and Discrete Mathematics--emphasizing problem solving, real-world applications, and the use…

  17. Framework for Disciplinary Writing in Science Grades 6-12: A National Survey

    Science.gov (United States)

    Drew, Sally Valentino; Olinghouse, Natalie G.; Faggella-Luby, Michael; Welsh, Megan E.

    2017-01-01

    This study investigated the current state of writing instruction in science classes (Grades 6-12). A random sample of certified science teachers from the United States (N = 287) was electronically surveyed. Participants reported on their purposes for teaching writing, the writing assignments most often given to students, use of evidence-based…

  18. Fever Management in Parents who Have Children Aged 0-5 Year

    Directory of Open Access Journals (Sweden)

    S. Reshadat

    2012-07-01

    Full Text Available Introduction & Objective: Fever is very common in children and is usually due to self-limiting viral infections. Management of fever is based on culture, community and religion of people all over the world. Parental concerns arise in part because of the belief that fever is a disease rather than a symptom or sign of illness. Misconceptions about childhood fevers heighten parents' concerns leading to inappropriate use of antipyretic drugs or overdosing may cause drug toxicity and frequent use of health care services. This study aimed to identify parental views of fever management in their children aged 0-5 yr.Materials & Methods: In this cross sectional study, 350 parents with children less than 5 years referred to various units of clinics covered by community oriented center of Kermanshah, completed the research questionnaire. Validity and reliability of the questionnaire were determined and the data was analyzed by SPSS Software.Results: Findings showed that the first medical care was sponging (53.1%. Sponging with saltwater was common (47.7% and Over - the - counter medications were (30%. Acetaminophen was the first drug in 90% of the cases. However, many parents express high levels of anxiety so that they seek for self-medication with antibiotic 34% of the cases. Our study showed that correlation between over concern about fever management and parents who had a positive past medical history in their children with P=0.02, parents education (P=0.018 and in employed mothers (P=0.005 was statistically significant.Conclusion: Considerable efforts will be required to educate parents about fever and its management.(Sci J Hamadan Univ Med Sci 2012;19(2:28-33

  19. Characterization of a High Strength, Refractory High Entropy Alloy, AlMo0.5NbTa0.5TiZr

    Science.gov (United States)

    Jensen, Jacob

    High entropy alloys (HEAs) are a relatively new class of materials that have garnered significant interest over the last decade due to their intriguing balance of properties including high strength, toughness, and corrosion resistance. In contrast to conventional alloy systems, HEAs are based on four or more principal elements with near equimolar concentrations and tend to have simple microstructures due to the preferential formation of solid solution phases. HEAs appear to offer new pathways to lightweighting in structural applications, new alloys for elevated temperature components, and new magnetic materials, but more thorough characterization studies are needed to assess the viability of the recently developed multicomponent materials. One such HEA, AlMo0.5NbTa0.5TiZr, was selected to be the basis for this characterization study in part due to its strength at elevated temperatures (sigma0.2 = 1600 MPa at T = 800 °C) and low density compared with commercially available Ni-based superalloys. The refractory element containing HEA composition was developed in order to balance the high temperature strength of the refractory elements with the desirable properties achieved by the high entropy alloying design approach for potential use in aerospace thermal protection and structural applications. Ingots of AlMo0.5NbTa0.5TiZr were cast by vacuum arc melting followed by hot isostatic pressing (HIP) and homogenization at 1400 °C for 24 hrs with a furnace cool of 10 °C/min. The resulting microstructure was characterized at multiple length scales using x-ray diffraction (XRD), scanning transmission electron microscopy (SEM), conventional and scanning transmission electron microscopy (TEM and STEM), and x-ray energy dispersive spectroscopy (XEDS). The microstructure was found to consist of a periodic, coherent two phase mixture, where a disordered bcc phase is aligned orthogonally in an ordered B2 phase. Through microstructural evolution heat treatment studies, the

  20. Effects of Mg substitution on the structural and magnetic properties of Co0.5Ni0.5-x Mg x Fe2O4 nanoparticle ferrites

    Science.gov (United States)

    R, M. Rosnan; Z, Othaman; R, Hussin; Ali, A. Ati; Alireza, Samavati; Shadab, Dabagh; Samad, Zare

    2016-04-01

    In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Co0.5Ni0.5-x Mg x Fe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of ˜ 32 nm to ˜ 36 nm. The lattice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2+ substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from ˜ 57.35 emu/g to ˜ 61.49 emu/g and ˜ 603.26 Oe to ˜ 684.11 Oe (1 Oe = 79.5775 A·m-1), respectively. The higher values of magnetization M s and M r suggest that the optimum composition is Co0.5Ni0.4Mg0.1Fe2O4 that can be applied to high-density recording media and microwave devices. Project supported by the Ibnu Sina Institute for Scientific and Industrial Research, Physics Department of Universiti Teknologi Malaysia and the Ministry of Education Malaysia (Grant Nos. Q.J130000.2526.04H65).

  1. Effects of strain on the magnetic and transport properties of the epitaxial La0.5Ca0.5MnO3 thin films

    International Nuclear Information System (INIS)

    Zarifi, M.; Kameli, P.; Ehsani, M.H.; Ahmadvand, H.; Salamati, H.

    2016-01-01

    The epitaxial strain can considerably modify the physical properties of thin films compared to the bulk. This paper reports the effects of substrate-induced strain on La 0.5 Ca 0.5 MnO 3 (LCMO) thin films, grown on (100) SrTiO 3 (STO) and LaAlO 3 (LAO) substrates by pulsed laser deposition technique. Transport and magnetic properties were found to be strongly dependent on strain type. It is also shown that compressive (tensile) strain leads to the increase (decrease) in the magnetization of the films. Moreover, it was observed that all LCMO films deposited on both LAO and STO substrates behave as an insulator, but LCMO/LAO thin films with compressive strain have lower resistivity than LCMO/STO thin films with tensile strain. Applying magnetic field to LCMO/STO thin films with thickness of 25 and 50 nm leads to very small change in the resistivity, while the effects of magnetic field on the sample with thickness of 125 nm leads to an insulator–metal transition. For LCMO/LAO thin films, the magnetic field has a strong impact on the resistivity of samples. The results show that the magnetoresistance (MR) is enhanced by increasing film thickness for LCMO/LAO samples, due to the relatively stronger phase separation. For LCMO/STO thin films MR is drastically decreased by reduction of film thickness, which is attributed to the enhancement of the charge–orbital order (CO–O) accompanying the complex spin order (the so-called CE type). The changes of the antiferromagnetic structure from the CE to C type and the enhancement of the CE type could be attributed to the in-plane compressive and tensile strain, respectively. - Highlights: • Epitaxial La 0.5 Ca 0.5 MnO 3 thin films, grown on (100) SrTiO 3 and LaAlO 3 substrates. • The compressive strain leads to the increase in the magnetization of the films. • The tensile strain leads to the decrease in the magnetization of the films. • The magnetoresistance is enhanced by increasing film thickness.

  2. Climate Prediction Center(CPC)Infra-Red (IR) 0.5 degree Dataset

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Climate Prediction Center 0.5 degree IR dataset was created from all available individual geostationary satellite data which have been merged to form nearly seamless...

  3. Backscatter 0.5m TIFF Mosaic of St. Thomas, US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  4. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Thomas, US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the south shore of St. Thomas, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  5. Giant strain with ultra-low hysteresis and high temperature stability in grain oriented lead-free K0.5Bi0.5TiO3-BaTiO3-Na0.5Bi0.5TiO3 piezoelectric materials.

    Science.gov (United States)

    Maurya, Deepam; Zhou, Yuan; Wang, Yaojin; Yan, Yongke; Li, Jiefang; Viehland, Dwight; Priya, Shashank

    2015-02-26

    We synthesized grain-oriented lead-free piezoelectric materials in (K0.5Bi0.5TiO3-BaTiO3-xNa0.5Bi0.5TiO3 (KBT-BT-NBT) system with high degree of texturing along the [001]c (c-cubic) crystallographic orientation. We demonstrate giant field induced strain (~0.48%) with an ultra-low hysteresis along with enhanced piezoelectric response (d33 ~ 190pC/N) and high temperature stability (~160°C). Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) results demonstrate smaller size highly ordered domain structure in grain-oriented specimen relative to the conventional polycrystalline ceramics. The grain oriented specimens exhibited a high degree of non-180° domain switching, in comparison to the randomly axed ones. These results indicate the effective solution to the lead-free piezoelectric materials.

  6. Moessbauer study of nickel containing 0.5% iron between room temperature and the Curie point

    International Nuclear Information System (INIS)

    Longworth, G.; Cranshaw, T.E.

    1983-01-01

    The Moessbauer measurements of the temperature variation of the spectra for nickel containing 0.5% iron by Hirsch have been repeated for a similar sample. No evidence was found for the magnetic first order transition postulated by Hirsch. (orig.)

  7. Backscatter 0.5m TIFF Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands. NOAA's NOS/NCCOS/CCMA Biogeography...

  8. Dielectric and AC-conductivity studies of Dy2O3 doped (K0.5Na0.5NbO3 ceramics

    Directory of Open Access Journals (Sweden)

    Mahesh Peddigari

    2014-08-01

    Full Text Available (K0.5Na0.5NbO3 + x wt.% Dy2O3 (x = 0–1.5 ferroelectric ceramics were prepared by conventional solid state reaction method. XRD patterns revealed that orthorhombic symmetry has transformed into psuedocubic symmetry with increasing the substitution of Dy3+ in the Na+ site. Temperature and frequency dependences of relative dielectric permittivity maximum conforms the transformation from normal ferroelectric to relaxor ferroelectric behaviour. Frequency dependence of the relative dielectric permittivity maximum temperature observed for the samples with x ≥ 1.0 and satisfied the Vogel–Fulcher law. The diffuseness exponent γ (1.27–1.95 estimated from the high temperature slopes of the diffused dielectric permittivity data reveals that the degree of relaxor behavior increases with increasing the amount of Dy2O3. The temperature dependence of AC-conductivity σAC (T analysis in the range 310 K < T < 470 K reveals the existence of variable range hopping of charge carriers with average hopping length RH and hopping energy EH are in the range 8.5–27 Å and 48–153 meV, respectively. Voltage dependent dielectric constant measurements confirm the ferroelectric nature of KNN+ x wt% Dy2O3 ceramics.

  9. DC-bias and visible light effect on dielectric characteristics of La0.5Cr0.5TiO3+δ

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2017-10-01

    Full Text Available La0.5Cr0.5TiO3+δ ceramic sample was prepared via traditional solid-state reaction route. Frequency and temperature dependence of dielectric permittivity were studied in the range of 102 ~ 106 Hz and of 77 ~ 360 K, respectively. It was observed that extraordinarily high low-frequency dielectric constants appeared at room temperature, and dielectric relaxation peaks shifted to higher temperature with increasing frequency. In the dc-bias studies, it was also found that the dielectric permittivity had obviously dc-bias dependence in low frequency, but independence as the frequency above 14 kHz. Interestingly, the dielectric characteristics of the sample had obvious light dependence at room temperature within the measured frequency range. The results demonstrate that visible light improves the dielectric properties of the ceramic by means of I–V and complex impedance analysis. Keywords: Ceramics, Dielectric properties, Dc-bias dependence, Visible light dependence

  10. Bipolar resistive switching properties of Hf{sub 0.5}Zr{sub 0.5}O{sub 2} thin film for flexible memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhipeng; Zhu, Jun; Zhou, Yunxia; Liu, Xingpeng [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu (China)

    2018-01-15

    An Au/Ni/Hf{sub 0.5}Zr{sub 0.5}O{sub 2}/Au flexible memory device fabricated on a polyethylene terephthalate substrate was studied for flexible resistive random access memory applications. A typical bipolar resistive switching behavior was revealed with an OFF/ON ratio of approximately 15. The reproducibility and uniformity were investigated using 100 repetitive write/erase cycles. The retention property did not degrade for up to 5 x 10{sup 4} s, and the resistive switching properties did not degrade even under bending conditions, which indicated good mechanical flexibility. The current-voltage characteristics of the memory device show a Poole-Frenkel emission conduction mechanism in the high-voltage region in the high-resistance state, while in the low-voltage region, the Ohmic contact and space charge limit current responded to the low-resistance state and high-resistance state, respectively. Combined with the conductance mechanism, the resistive switching behavior is attributed to conductive filaments forming and rupturing due to oxygen vacancies migrating under the external driving electric field. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Magnetoelectric coupling study in multiferroic Pb(Fe0.5Nb0.5)O3 ceramics through small and large electric signal standard measurements

    International Nuclear Information System (INIS)

    Raymond, Oscar; Siqueiros, Jesus M.; Font, Reynaldo; Portelles, Jorge

    2011-01-01

    Multifunctional multiferroic materials such as the single phase compound Pb(Fe 0.5 Nb 0.5 )O 3 (PFN), where ferroelectric and antiferromagnetic order coexist, are very promising and have great interest from the academic and technological points of view. In this work, coupling of the ferroelectric and magnetic moments is reported. For this study, a combination of the small signal response using the impedance spectroscopy technique and the electromechanical resonance method with the large signal response through standard ferroelectric hysteresis measurement, has been used with and without an applied magnetic field. The measurements to determine the electrical properties of the ceramic were performed as functions of the bias and poling electric fields. A simultaneous analysis of the complex dielectric constant ε-tilde, impedance Z-tilde, electric modulus M-tilde, admittance Y-tilde, and the electromechanical parameters and coupling factors is presented. The results are correlated with a previous study of structural, morphological, small signal dielectric frequency-temperature response, and the ferroelectric hysteretic, magnetic and magnetodielectric behaviors. The observed shifts of the resonance and antiresonance frequency values can be associated with change of the ferroelectric domain size favored by the readjustment of the oxygen octahedron when the magnetic field is applied. From P-E hysteresis loops obtained without and with an external applied magnetic field, a dc magnetoelectric coupling effect with maximum value of 4 kV/cm T (400 mV/cm Oe) was obtained.

  12. Pressure-induced structural and semiconductor-semiconductor transitions in C o0.5M g0.5C r2O4

    Science.gov (United States)

    Rahman, S.; Saqib, Hajra; Zhang, Jinbo; Errandonea, D.; Menéndez, C.; Cazorla, C.; Samanta, Sudeshna; Li, Xiaodong; Lu, Junling; Wang, Lin

    2018-05-01

    The effect of pressure on the structural, vibrational, and electronic properties of Mg-doped Cr bearing spinel C o0.5M g0.5C r2O4 was studied up to 55 GPa at room-temperature using x-ray diffraction, Raman spectroscopy, electrical transport measurements, and ab initio calculations. We found that the ambient-pressure phase is cubic (spinel-type, F d 3 ¯m ) and underwent a pressure-induced structural transition to a tetragonal phase (space group I 4 ¯m 2 ) above 28 GPa. The ab initio calculation confirmed this first-order phase transition. The resistivity of the sample decreased at low pressures with the existence of a low-pressure (LP) phase and started to increase with the emergence of a high-pressure (HP) phase. The temperature dependent resistivity experiments at different pressures illustrated the wide band gap semiconducting nature of both the LP and HP phases with different activation energies, suggesting a semiconductor-semiconductor transition at HP. No evidence of chemical decomposition or a semiconductor-metal transition was observed in our studies.

  13. Effect of zinc substitution on the structural, electrical and magnetic properties of nano-structured Ni0.5Co0.5Fe2O4 ferrites

    Science.gov (United States)

    Babu, K. Vijaya; Sailaja, B.; Jalaiah, K.; Shibeshi, Paulos Taddesse; Ravi, M.

    2018-04-01

    A series of Ni0.5Co0.5-xZnxFe2O4 (x = 0, 0.02, 0.04 and 0.06) nanoferrites were synthesized by sol-gel method using citric acid as chelating reagent. The synthesized ferrite systems are characterized by XRD, SEM, FTIR, ESR and dielectric techniques. The formation of cubic spinel phase belonging to space group Fd3m is identified from the X-ray diffraction patterns. SEM showed the particles are in spherical shape with an average grain size 5-10 nm. FTIR spectra portrait the fundamental absorption bands in the range 400-600 cm-1 relating to octahedral and tetrahedral sites. Dielectric properties are investigated over the frequency range of 20 Hz to 1 MHz at room temperature. A difference in dielectric constant (εr) and dissipation factor (tanδ) of the ferrites has been observed. The dielectric constant and dielectric loss tangent decreases exponentially with increase in frequency. The obtained results are good agreeing with the reported values.

  14. Aging, rejuvenation, and memory effects in short-range Ising spin glass: Cu_0.5Co_0.5Cl_2-FeCl3 GBIC

    Science.gov (United States)

    Suzuki, M.; Suzuki, I. S.

    2004-03-01

    Cu_0.5Co_0.5Cl_2-FeCl3 GBIC undergoes a spin glass (SG) transition at Tg (= 3.92 ± 0.11 K). The system shows a dynamic behavior that has some similarities and some significant differences compared to a 3D Ising SG.^1 Here we report on non-equilibrium aging dynamics which has been studied using zero-field cooled (ZFC) magnetization and low frequency AC magnetic susceptibility.^2 The time dependence of the relaxation rate S(t) = (1/H)dM_ZFC/dln t for the ZFC magnetization after the ZFC aging protocol, shows a peak at a characteristic time t_cr near a wait time t_w, corresponding to a crossover from quasi equilibrium dynamics to non-equilibrium. The time t_cr strongly depends on t_w, temperature, magnetic field, and the temperature shift. The rejuvenation effect is observed in both i^' and i^'' under the T-shift and H-shift procedures. The memory of the specific spin configurations imprinted during the ZFC aging protocol can be recalled when the system is re-heated at a constant heating rate. The aging, rejuvenation, and memory effects are discussed in terms of the scaling concepts derived from numerical studies on 3D Edwards-Anderson spin glass model. 1. I.S. Suzuki and M. Suzuki, Phys. Rev. B 68, 094424 (2003) 2. M. Suzuki and I.S. Suzuki, cond-mat/0308285

  15. First-principles study of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuan Xu [Computational Materials Science Center, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2008-06-15

    We have theoretically investigated basic properties of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO{sub 2}-terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO{sub 2}-terminated surface is much larger than that of the Ti{sub 2}O{sub 4}-terminated one. The surface state appears in the band structure of the Ti{sub 2}O{sub 4}-terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO{sub 2}-terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. First-principles study of the (001) surface of cubic Ba0.5Sr0.5TiO3

    International Nuclear Information System (INIS)

    Wang, Yuan Xu

    2008-01-01

    We have theoretically investigated basic properties of the (001) surface of cubic Ba 0.5 Sr 0.5 TiO 3 (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO 2 -terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO 2 -terminated surface is much larger than that of the Ti 2 O 4 -terminated one. The surface state appears in the band structure of the Ti 2 O 4 -terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO 2 -terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Tunable strain effect and ferroelectric field effect on the electronic transport properties of La0.5Sr0.5CoO3 thin films

    Science.gov (United States)

    Zhu, Q. X.; Wang, W.; Zhao, X. Q.; Li, X. M.; Wang, Y.; Luo, H. S.; Chan, H. L. W.; Zheng, R. K.

    2012-05-01

    Tensiled La0.5Sr0.5CoO3 (LSCO) thin films were epitaxially grown on piezoelectric 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. Due to the epitaxial nature of the interface, the lattice strain induced by ferroelectric poling or the converse piezoelectric effect in the PMN-PT substrate is effectively transferred to the LSCO film and thus reduces the tensile strain of the film, giving rise to a decrease in the resistivity of the LSCO film. We discuss these strain effects within the framework of the spin state transition of Co3+ ions and modification of the electronic bandwidth that is relevant to the induced strain. By simultaneously measuring the strain and the resistivity, quantitative relationship between the resistivity and the strain was established for the LSCO film. Both theoretical calculation and experimental results demonstrate that the ferroelectric field effect at room temperature in the LSCO/PMN-PT field-effect transistor is minor and could be neglected. Nevertheless, with decreasing temperature, the ferroelectric field effect competes with the strain effect and plays a more and more important role in influencing the electronic transport properties of the LSCO film, which we interpreted as due to the localization of charge carriers at low temperature.

  18. Structural and dielectric properties of La- and Ti-modified K0.5Na0.5NbO3 ceramics

    International Nuclear Information System (INIS)

    Fuentes, J.; Perez, A.; Portelles, J.; Durruthy-Rodriguez, M.D.; Ostos, C.; Raymond, O.; Heiras, J.; Cruz, M.P.; Siqueiros, J.M.

    2012-01-01

    Studies of structural and dielectric properties of lead-free perovskite K 0.5 Na 0.5 NbO 3 (KNN) ceramics obtained by the substitution of 5 at% of La and Ti for ions in the A-site and B-site, respectively, and sintered at different temperatures between 1100 C and 1190 C, are presented. X-ray diffraction patterns show the successful formation of an orthorhombic perovskite phase similar to that of pure KNN. The effect of doping and sintering temperature on the dielectric properties of the resulting ceramics is discussed. Simultaneous substitution of La and Ti into the KNN (KNNLaTi) causes a shift in the ferroelectric-paraelectric phase transition temperature from that of pure KNN (420 C) to considerably lower ones (81 to 110 C) for the modified compounds. A particularly important result is the appearance of a single peak in the permittivity vs. temperature curve associated with the ferroelectric-paraelectric phase transition, where the KNNLaTi compound changes from orthorhombic to cubic structure, instead of the two reported for pure KNN. This transition exhibits the characteristics of a normal diffuse phase transition with an incipient relaxer behavior. (orig.)

  19. From beta-relaxation to alpha-decay: Atomistic picture from molecular dynamics simulations for glass-forming Ni0.5Zr0.5 melt

    Energy Technology Data Exchange (ETDEWEB)

    Teichler, Helmar [Inst. Materialphysik, Univ Goettingen (Germany)

    2013-07-01

    In glass-forming melts the decay of structural fluctuation shows the well known transition from beta-relaxation (von-Schweidler law with exponent b) to alpha-decay (KWW law with exponent beta). Here we present results from molecular dynamics simulations for a metallic glass forming Ni0.5Zr0.5 model aimed at giving an understanding of this transition on the atomistic scale. At the considered temperature below mode coupling Tc, the dynamics of the system can be interpreted by residence of the particles in their neighbour cages and escape from the cages as rare processes. Our analysis yields that the fraction of residing particles is characterized by a hierarchical law in time, with von-Schweidler b explicitly related to the exponent of this law. In the alpha-decay regime the stretching exponent reflects, in addition, floating of the cages due to strain effects of escaped particles. Accordingly, the change from beta-relaxation to alpha-decay indicates the transition from low to large fraction of escaped particles.

  20. Synthesis of high aspect ratio of Ni 0.5Zn 0.5Fe 2O 4 platelets for electromagnetic devices

    Science.gov (United States)

    Hallynck, Sylvain; Pourroy, Geneviève; Vilminot, Serge; Jacquart, Pierre-Marie; Autissier, Denis; Vukadinovic, Nicolas; Pascard, Hubert

    2006-01-01

    Ni 0.5Zn 0.5Fe 2O 4 ferrite platelets of 5 to 300 μm have been obtained by reaction in a molten salt between hematite platelets, NiO and ZnO powders. The hematite platelets are obtained by a hydrothermal treatment in an alkaline medium between 180 and 270 °C through a dissolution-recrystallization mechanism from maghemite which crystallizes first. The key parameter for size control is the mixture alkalinity. The largest platelets are obtained for [Fe 3+] = 2.0 mol dm -3 and [OH -] = 15.3 N. The size distribution is narrow and the aspect ratio about 30. The reaction with nickel and zinc oxides yields the formation of polycrystalline platelets through a topotactic reaction allowing the platelet morphology, initial shape and size to be conserved. SEM observations reveal the ferrite platelets are made of adjacent micronic ferrite crystals with their [111] faces parallel to the platelet surface. Increasing the reaction temperature promotes an enlargement of the [111] faces. The respective solubilities of oxides and ferrites in the molten salts control the ferrite stoichiometry. KCl as a flux gives better results than NaCl with no modification of the crystal shape and no ZnO loss.

  1. Electrophoretic deposition of Cu2ZnSn(S0.5Se0.5)4 films using solvothermal synthesized nanoparticles

    Science.gov (United States)

    Badkoobehhezaveh, Amir Masoud; Abdizadeh, Hossein; Golobostanfard, Mohammad Reza

    2018-01-01

    In this paper, a simple, practical, and fast solvothermal route is presented for synthesizing the Cu2ZnSn(S0.5Se0.5)4 nanoparticles (CZTSSe). In this method, the precursors were dissolved in triethylenetetramine and placed in an autoclave at 240 °C for 1 h under controlled pressure and constant stirring. After washing the samples for several times with absolute ethanol, the obtained CZTSSe nanoparticles were successfully deposited on fluorine doped tin oxide substrates by convenient electrophoretic deposition (EPD) using colloidal nanoparticles. The most appropriate parameters for EPD of pre-synthesized CZTSSe nanoparticles which result in proper surface properties, controlled thickness, and high film quality are investigated by adjusting applied voltage, pH, and deposition time. X-ray diffraction pattern and Raman spectroscopy of the pre-synthesized nanoparticles show kesterite structure formation. The particle size of the CZTSSe nanoparticles is in the range of 100 to 400 nm and for some agglomerates, it is about 2 µm confirmed by scanning electron microscope. The deposited film with optimized parameter has acceptable quality without any crack in it with the thickness of about 4-5 µm. Energy-dispersive X-ray spectroscopy confirms that the chemical composition of the samples is in near stoichiometric Cu-poor and Zn-rich region, which guarantees the p-type character of the film. The diffuse reflectance spectroscopy also demonstrates that the optical band gap of the sample is about 1.2 eV.

  2. Fabrication of Lead-Free Bi0.5Na0.5TiO3 Thin Films by Aqueous Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Mads Christensen

    2017-02-01

    Full Text Available Piezoelectric ceramics are widely used in actuator applications, and currently the vast majority of these devices are based on Pb ( Zr , Ti O 3 , which constitutes environmental and health hazards due to the toxicity of lead. One of the most promising lead-free material systems for actuators is based on Bi 0 . 5 Na 0 . 5 TiO 3 (BNT, and here we report on successful fabrication of BNT thin films by aqueous chemical solution deposition. The precursor solution used in the synthesis is based on bismuth citrate stabilized by ethanolamine, NaOH , and a Ti-citrate prepared from titanium tetraisopropoxide and citric acid. BNT thin films were deposited on SrTiO 3 and platinized silicon substrates by spin-coating, and the films were pyrolized and annealed by rapid thermal processing. The BNT perovskite phase formed after calcination at 500 °C in air. The deposited thin films were single phase according to X-ray diffraction, and the microstructures of the films shown by electron microscopy were homogeneous and dense. Decomposition of the gel was thoroughly investigated, and the conditions resulting in phase pure materials were identified. This new aqueous deposition route is low cost, robust, and suitable for development of BNT based thin film for actuator applications.

  3. EFECTO DEL ESPESOR EN LAS PROPIEDADES SUPERCONDUCTORAS Y ESTRUCTURALES DE PELÍCULAS DELGADAS DE FeSe0,5Te0,5

    Directory of Open Access Journals (Sweden)

    Oscar Rodríguez

    2012-07-01

    Full Text Available En este trabajo se investiga la influencia del espesor de la capa de FeSe0,5Te0,5 en las propiedades cristalinas y superconductoras de las películas depositadas sobre una capa buffer de hierro (Fe en sustratos de MgAl2O4, por el método de deposición por láser pulsado (PLD. El espesor de las capas superconductoras producidas son ~55nm y ~134nm. La película con menor espesor presenta mejores propiedades de textura (crecimiento orientado y una menor rugosidad superficial (RMS; verificadas por difracción de rayos X y AFM respectivamente. Esta misma película presenta una transición marcada al estado superconductor y una mayor temperatura crítica a diferencia de la película de mayor espesor. Se discute el efecto del espesor en las tensiones de la red superconductora.

  4. PRODUCCIÓN Y CARACTERIZACIÓN DEL NUEVO SISTEMA SUPERCONDUCTOR Yb0,5Ho0,5Ba2Cu3O7-d

    Directory of Open Access Journals (Sweden)

    Jully P. Peña

    2011-01-01

    Full Text Available Se reporta la caracterización del nuevo sistema superconductor Yb0,5Ho0,5Ba2Cu3O7-δ perteneciente a la familia de cupratos de alta temperatura TR123; el material fue producido utilizando el método de reacción de estado sólido (SSR con una temperatura de sinterizado de 910 °C. Se muestra la caracterización morfológica referente al comportamiento granular utilizando la técnica de Microscopía electrónica de barrido (SEM; la caracterización estructural, se logra sometiendo la muestra a difracción de rayos X (DRX y se obtienen los parámetros estructurales implementando el método de refinamiento Rietveld en el software GSAS, el material resulta poseer celdas unitarias ortorrómbicas tipo perovskita con un comportamiento superconductor que se evidencia en la curva de resistividad como función de la temperatura cuya derivada presenta un punto crítico en el valor correspondiente a la temperatura crítica Tc 92,61 K.

  5. Preparation of thin-film (Ba(0.5),Sr(0.5))TiO3 by the laser ablation technique and electrical properties

    Science.gov (United States)

    Yoon, Soon-Gil; Lee, Jai-Chan; Safari, A.

    1994-09-01

    The chemical composition and electrical properties were investigated for epitaxially crystallized (Ba(0.5),Sr(0.5))TiO3 (BST) films deposited on Pt/MgO and YBa2Cu3O(7-x) (YBCO)/MgO substrates by the laser ablation technique. Rutherford backscattering spectroscopy analysis shows that thin films on Pt/MgO have almost the same stoichiometric composition as the target material. Films deposited at 600 C exhibited an excellent epitaxial growth, a dielectric constant of 430, and a dissipation factor of 0.02 at 10 kHz frequency. They have a charge storage density of 40 fC/sq micron at an applied electric field of 0.15 MV/cm. Leakage current density of BST thin films on Pt/MgO was smaller than on YBCO/MgO. Their leakage current density is about 0.8 microA/sq cm at an applied electric field of 0.15 MV/cm.

  6. Ferroelastically and magnetically co-coupled resistive switching in Nd0.5Sr0.5MnO3/PMN-PT(011) multiferroic heterostructures

    Science.gov (United States)

    Zheng, Ming; Xu, Xiao-Ke; Ni, Hao; Qi, Ya-Ping; Li, Xiao-Min; Gao, Ju

    2018-03-01

    The phase separation, i.e., the competition between coexisting multi-phases, can be adjusted by external stimuli, such as magnetic field, electric field, current, light, and strain. Here, a multiferroic heterostructure composed of a charge-ordered Nd0.5Sr0.5MnO3 thin film and a ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal is fabricated to investigate the lattice strain and magnetic field co-control of phase separation in resistive switching. The stable and nonvolatile resistance tuning is realized at room temperature using the electric-field-induced reversible ferroelastic strain effect, which can be enhanced by 84% under the magnetic field. Moreover, the magnetoresistance can be effectively tuned by the electrically driven ferroelastic strain. These findings reveal that the ferroelastic strain and the magnetic field strongly correlate with each other and are mediated by phase separation. Our work provides an approach to design strain-engineered multifunctional memory devices based on complex oxides by introducing an extra magnetic field stimulus.

  7. A high stability Ni-La0.5Ce0.5O2-δ asymmetrical metal-ceramic membrane for hydrogen separation and generation

    Science.gov (United States)

    Zhu, Zhiwen; Sun, Wenping; Wang, Zhongtao; Cao, Jiafeng; Dong, Yingchao; Liu, Wei

    2015-05-01

    In this work, hydrogen permeation properties of Ni-La0.5Ce0.5O2-δ (LDC) asymmetrical cermet membrane are investigated, including hydrogen fluxes (JH2) under different hydrogen partial pressures, the influence of water vapor on JH2 and the long-term stability of the membrane operating under the containing-CO2 atmosphere. Ni-LDC asymmetrical membrane shows the best hydrogen permeability among LDC-based hydrogen separation membranes, inferior to Ni-BaZr0.1Ce0.7Y0.2O3-δ asymmetrical membrane. The water vapor in feed gas is beneficial to hydrogen transport process, which promote an increase of JH2 from 5.64 × 10-8 to 6.83 × 10-8 mol cm-2 s-1 at 900 °C. Stability testing of hydrogen permeation suggests that Ni-LDC membrane remains stable against CO2. A dual function of combining hydrogen separation and generation can be realized by humidifying the sweep gas and enhance the hydrogen output by 1.0-1.5 times. Ni-LDC membrane exhibits desirable performance and durability in dual-function mode. Morphologies and phase structures of the membrane after tests are also characterized by SEM and XRD.

  8. Biodiesel production in methyl esterification in the frying oil using catalyst Ni_0_,_5Zn_0_,_5Fe_2O_4 to produce biodiesel

    International Nuclear Information System (INIS)

    Vasconcelos, E.V.; Dantas, J.; Pereira, K.B.O.; Barros, A.B.; Moura, T.F.B.; Costa, A.C.F.M.

    2016-01-01

    The use of magnetic catalysts for biodiesel production has gaining prominence because of possibility about its recovery and its reuse, as well as, the reuse of materials that would be discarded in the environment. Thus, we propose to evaluate the efficiency of the catalyst Ni_0_,_5Zn_0_,_5Fe_2O_4 in methyl esterification in the frying oil to produce biodiesel. The catalyst was produced by combustion reaction using containers with different production capacity and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectrometry with Fourier transform (FTIR). The catalytic tests were conducted in a stainless steel reactor at 180°C/1h, 2% of catalyst, oil/ethanol ratio of 1:12. Regardless of the container production capacity it was verified the catalyst obtaining with the major phase formation of the inverse spinel and traces of segregated phases with an average crystallite size of 42.13, 32.07 and 36.93 nm. All catalysts showed satisfactory results with conversions of 74%, 77% and 71%. (author)

  9. Stability of charge and orbital order in half-doped Y{sub 0.5}Ca{sub 0.5}MnO{sub 3} nanocrystallites

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Putul Malla, E-mail: putularun@gmail.com; Ghosh, Barnali, E-mail: barnali@bose.res.in; Raychaudhuri, A. K., E-mail: arup@bose.res.in [S N Bose National Centre for Basic Sciences, Unit for Nano Science, Department of Condensed Matter Physics and Materials Science (India); Kaushik, S. D.; Siruguri, V. [UGC-DAE Consortium for Scientific Research Mumbai Centre, R-5 Shed, Bhabha Atomic Research Centre (India)

    2013-04-15

    In this paper, we report a detailed study of the structure, magnetic, and electrical transport properties in nanocrystallites of hole-doped manganite Y{sub 0.5}Ca{sub 0.5}MnO{sub 3}, with the aim to study the effect of size reduction on the stability of the charge-orbital order and the antiferromagnetic spin order that are seen in the bulk samples of the half-doped manganite. The investigations have been done in the general context of investigating how size reduction affects competing interactions in complex oxides and thus, changes their ground state. The bulk sample of the material (average crystallite size {approx}1 {mu}m), with the smallest radius of the cation in A-site (Y), shows a robust charge and orbital ordered insulating state below the transition temperature near 290 K and an antiferromagnetic spin order at 110 K. The experiments carried out on well-characterized nanocrystalline samples, with average crystallite sizes down to 75 nm, establish that the size reduction changes the structural parameters, and the charge and orbital ordering are suppressed. However, the antiferromagnetic spin order (as revealed by neutron diffraction experiments carried out down to 2 K) persists in the nanocrystallites and co-exists with ferromagnetic order below 110 K. The nanocrystalline samples have significant lower resistivities (by few orders) compared to those of the bulk samples in the temperature range 10-300 K. This corroborates the formation of the ferromagnetic moments in the nanocrystallites.

  10. Crystallization of Sr0.5Ba0.5Nb2O6 Thin Films on LaNiO3 Electrodes by RF Magnetron Reactive Sputtering

    Science.gov (United States)

    Jong, Chao-An; Gan, Jon-Yiew

    2000-02-01

    Strontium barium niobium (Sr0.5Ba0.5Nb2O6) (SBN) thin films are prepared on conductive-oxide LNO (LaNiO3) electrodes by the rf magnetron sputtering system. Instead of conventional furnace annealing, SBN thin films are crystallized by rapid thermal annealing (RTA) above 700°C for 5 min. The textured SBN films are crystallized with two orientations: one is the (001) or (310) direction, and the other is the (002) or (620) direction. Films compositions measured by the electron spectroscopy of chemical analysis (ESCA) quantitative analysis method show nearly the same stoichiometric ratio as the target. The depth profiles of SBN films and the target are examined by secondary ion mass spectrometer (SIMS). The concentrations of the films are quite uniform. After being heat treated at 800°C for 5 min by RTA, La and Ni diffuse into the SBN film. The diffusion coefficient of La in SBN films is also calculated.

  11. Understanding the influence of surface chemical states on the dielectric tunability of sputtered Ba0.5Sr0.5TiO3 thin films

    Science.gov (United States)

    Venkata Saravanan, K.; Raju, K. C. James

    2014-03-01

    The surface chemical states of RF-magnetron sputtered Ba0.5Sr0.5TiO3 (BST5) thin films deposited at different oxygen mixing percentage (OMP) was examined by x-ray photoelectron spectroscopy. The O1s XPS spectra indicate the existence of three kinds of oxygen species (dissociated oxygen ion O2 -, adsorbed oxide ion O- and lattice oxide ion O2-) on the films’ surface, which strongly depends on OMP. The presence of oxygen species other than lattice oxygen ion makes the films’ surface highly reactivity to atmospheric gases, resulting in the formation of undesired surface layers. The XPS results confirm the formation of surface nitrates for the films deposited under oxygen deficient atmosphere (OMP ≦̸ 25%), whereas the films deposited in oxygen rich atmosphere (OMP ≧̸ 75%) show the presence of metal-hydroxide. The influence of a surface dead layer on the tunable dielectric properties of BST5 films have been studied in detail and are reported. Furthermore, our observations indicate that an optimum ratio of Ar:O2 is essential for achieving desired material and dielectric properties in BST5 thin films. The films deposited at 50% OMP have the highest dielectric tunability of ~65% (@280 kV cm-1), with good ɛ r-E curve symmetry of 98% and low tan δ of 0.018. The figure of merit for these films is about 35, which is promising for frequency agile device applications.

  12. The down-conversion and up-conversion photoluminescence properties of Na0.5Bi0.5TiO3:Yb3+/Pr3+ ceramics

    International Nuclear Information System (INIS)

    Huang, Yinpeng; Luo, Laihui; Wang, Jia; Zuo, Qianghui; Yao, Yongjie; Li, Weiping

    2015-01-01

    Na 0.5 Bi 0.5−x−y Yb x Pr y TiO 3 (NBT:xYb/yPr) ceramics with different Yb and Pr contents are prepared. Both the down-conversion (DC) and up-conversion (UC) photoluminescence (PL) of the ceramics via 453 and 980 nm excitation, respectively, are investigated. The effect of Yb 3+ and Pr 3+ doping contents on the DC and UC PL is significantly different from each other. Furthermore, the UC PL of the ceramics as a function of temperatures is measured to investigate the UC process in detail. Based on energy level diagram of Pr 3+ and Yb 3+ ions and the DC and UC PL spectra, the DC and UC PL mechanisms of Pr 3+ and Yb 3+ ions are discussed. Especially, the UC PL mechanism is clarified, which is different from the previously reported literature. Also, the temperature sensing properties of the ceramics are studied based on the photoluminescence ratio technique, using the thermal coupling energy levels of Pr 3+

  13. Improved ferroelectric and photoluminescence properties in Pr3+ substituted Na0.5Bi0.5TiO3 synthesized using hydrothermal route

    Science.gov (United States)

    Goutham, Cilaveni; Kandula, Kumara Raja; Raavi, Sai Santhosh Kumar; Asthana, Saket

    2018-04-01

    Nanocrystalline Pr3+ substituted NBT was synthesized using hydrothermal technique. Pr3+ modifies the ferroelectric NBT optically active and enhances the electrical properties with small structural changes. Aiming to the development of the bottom up optoelectronic devices this optimized nanoscale Na0.5Bi0.5-xPrxTiO3(x = 0.005) compound is synthesized hydrothermally. X-ray diffraction pattern shows that the system is stabilized in the Rhombohedral (space groupR3c) phase indicating the local strain inhomogeneity. PE loop shows that there is a decrement in the Ec value compared with compounds synthesized using conventional methods. The strong red emission assigned to prominent transition of the Pr3+ ions at 610nm was observed along with weak blue-green emission, indicating the potential use of the system. Energy transfer from host system to Pr3+ ions is responsible for red emission while blue green emission is due to quenching of 3P0 induced by intervalence charge transfer state.

  14. Multi-interface roughness effects on electron mobility in a Ga0.5In0.5P/GaAs multisubband coupled quantum well structure

    International Nuclear Information System (INIS)

    Sahu, Trinath; Shore, K Alan

    2009-01-01

    We analyse the effect of interface roughness scattering on low temperature electron mobility μ n mediated by intersubband interactions in a multisubband coupled Ga 0.5 In 0.5 P/GaAs quantum well structure. We consider a barrier δ-doped double quantum well system in which the subband electron mobility is limited by the interface roughness scattering μ IR n and ionized impurity scattering μ imp n . We analyse the effect of the intersubband interaction and coupling of subband wavefunctions through the barrier on the intrasubband and intersubband transport scattering rates. We show that the intersubband interaction controls the roughness potential of different interfaces through the dielectric screening matrix. In the case of lowest subband occupancy, the mobility is mainly governed by the interface roughness of the central barrier. Whereas when two subbands are occupied, the interface roughness of the outer barrier predominates due to intersubband effects. The influence of the intersubband interaction also exhibits interesting results on the well width up to which the interface roughness dominates in a double quantum well structure

  15. Influence of Chromium Doping on Electrical and Magnetic Behavior of Nd0.5Sr0.5MnO3 System

    Science.gov (United States)

    Lalitha, G.; Pavan Kumar, N.; Venugopal Reddy, P.

    2018-04-01

    With a view to understand the influence of chromium doping at the Mn site on the electrical and magnetic behavior of the Nd0.5Sr0.5MnO3 manganite system, a series of samples were prepared by the citrate sol-gel route method. The samples were characterized structurally by XRD. A systematic investigation of electrical resistivity over a temperature range 5-300 K was carried out mainly to understand the magneto-transport behavior in these materials. Studies on the variation of magnetization with temperature over a temperature range 80-330 K were undertaken. Investigation of magnetization at different magnetic fields at two different temperatures, viz. 80 and 300 K, was also carried out. The results show that chromium doping gave typical electrical and magnetic properties. It has been concluded that the coexistence of charge ordered and ferromagnetic phases induced by chromium doping plays an important role in the low-temperature behavior of the system.

  16. Conductivity fluctuation in the high temperature superconductor with planar weight disparity Y0.5Sm0.5Ba2Cu3O7-δ

    International Nuclear Information System (INIS)

    Barrera, E.W.; Rojas Sarmiento, M.P.; Rincon, L.F.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2007-01-01

    The synthesis of the Y 0.5 Sm 0.5 Ba 2 Cu 3 O 7-δ superconducting material by the standard solid state reaction is reported. DC resistivity measurements reveal the improvement of the critical temperature (T c ) when substitution of exact 50-50 mix of Yttrium and Samarium is performed. A bulk T c = 101 K was determined by the criterion of the maximum in the temperature derivative of electrical resistivity. Structure characterization by means the x-ray diffraction technique shows the crystalline appropriated distribution of Yttrium and Samarium to create substantial planar weight disparity (PWD) in alternating layers. This PWD increases T c in copper-oxide superconductors. In order to examine the effect of PWD on the pairing mechanism close to T c , conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. We found the occurrence of Gaussian and genuinely critical fluctuations. Our results are in agreement with reports on YBa 2 Cu 3 O 7-δ , but an enhancement of the Gaussian fluctuation regimes was experimentally detected as a result of the PWD. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov-Larkin theory. The genuinely critical exponent is interpreted by the 3D-XY model as corresponding with the dynamical universality class of the E-model. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3.

    Science.gov (United States)

    Li, Ming; Pietrowski, Martha J; De Souza, Roger A; Zhang, Huairuo; Reaney, Ian M; Cook, Stuart N; Kilner, John A; Sinclair, Derek C

    2014-01-01

    Oxide ion conductors find important technical applications in electrochemical devices such as solid-oxide fuel cells (SOFCs), oxygen separation membranes and sensors. Na0.5Bi0.5TiO3 (NBT) is a well-known lead-free piezoelectric material; however, it is often reported to possess high leakage conductivity that is problematic for its piezo- and ferroelectric applications. Here we report this high leakage to be oxide ion conduction due to Bi-deficiency and oxygen vacancies induced during materials processing. Mg-doping on the Ti-site increases the ionic conductivity to ~0.01 S cm(-1) at 600 °C, improves the electrolyte stability in reducing atmospheres and lowers the sintering temperature. This study not only demonstrates how to adjust the nominal NBT composition for dielectric-based applications, but also, more importantly, gives NBT-based materials an unexpected role as a completely new family of oxide ion conductors with potential applications in intermediate-temperature SOFCs and opens up a new direction to design oxide ion conductors in perovskite oxides.

  18. Selection of optimal sintering temperature of K0.5Na0.5NbO3 ceramics for electromechanical applications

    Directory of Open Access Journals (Sweden)

    Gaurav Vats

    2014-03-01

    Full Text Available This paper has considered the selection of the optimal processing parameter (sintering temperature leading to best possible properties of K0.5Na0.5NbO3 (KNN for electromechanical applications. Vital piezoelectric properties for such applications include the piezoelectric coupling coefficient (kp, piezoelectric coefficient (d31, Curie temperature (Tc, remanent polarization (Pr, coercive field (Ec, density (ρ, elastic compliance (S11E and S12E and dielectric loss (tan δ. The weights and priority of these physical properties for KNN are calculated using the modified digital logic (MDL method. The priority order of these properties used for the selection of optimal processing parameters is as d31>tan δ>S11E=S12E>Tc=Pr>ρ>kp>Ec. The weights obtained using MDL are further incorporated with analytic hierarchy process (AHP and VlseKriterijumska Optimisacija I Kompromisno Resenje (VIKOR in order to determine the optimal sintering temperature for KNN. Both methods suggest that 1080 °C and 1120 °C are the most and least desirable sintering temperatures, respectively. Finally, sensitivity analysis is performed for the robustness of our results and prediction of most influential parameter in terms of sensitivity. tan δ is found to be the most sensitive property for alteration in the present ranking.

  19. Extended x-ray absorption fine structure study of phase transitions in the piezoelectric perovskite K0.5Na0.5NbO3

    Science.gov (United States)

    Kodre, A.; Tellier, J.; Arčon, I.; Malič, B.; Kosec, M.

    2009-06-01

    Following an x-ray diffraction study of phase transitions of the piezoelectric perovskite K0.5Na0.5NbO3 the structural changes of the material are studied using extended x-ray absorption fine structure analysis, whereby the neighborhood of Nb atom is determined in the temperature range of monoclinic, tetragonal, and cubic phases. Within the entire range Nb atom is displaced from the center of the octahedron of its immediate oxygen neighbors, as witnessed by the splitting of Nb-O distance. The model shows high prevalence of the displacement in the (111) crystallographic direction of the simple perovskite cell. The corresponding splitting of the Nb-Nb distance is negligible. There is no observable disalignment of the linear Nb-O-Nb bonds from the ideal cubic arrangement, judging from the intensity of the focusing of the photoelectron wave on the Nb-Nb scattering path by the interposed oxygen atom. As a general result, the phase transitions are found as an effect of the long-range order, while the placement of the atoms in the immediate vicinity remains largely unaffected.

  20. An NMR study of Pr0.5Ca0.5Mn1-xGaxO3 (x = 0 and 0.03)

    International Nuclear Information System (INIS)

    Oates, C.J.; Sikora, M.; Zajac, D.; Rybicki, D.; Kapusta, Cz.; Riedi, P.C.; Martin, C.; Yaicle, M.; Maignan, A.

    2004-01-01

    An NMR study of polycrystalline Pr 0. 5Ca 0.5 Mn 1-x Ga x O 3 (x = 0 and 0.03) at 3 K is presented. Zero field spin echo spectra of the Ga doped compound consist of an overlapping 6: 9 ,71 Ga signal at 74 MHz (hyperfine field of 5.3 T), a 55 Mn double exchange line at 375 MHz (35.5 T) and a weak Mn 3+ signal between 400 and 550 MHz. Measurements in an applied field show a step-like increase in the double exchange line intensity, which corresponds to an increase in the amount of the ferromagnetic metallic phase. This coincides with a step-like feature in the bulk magnetization measurements. The effect is similar to that in the previous field dependent 55 Mn NMR measurements of Pr 0.67 Ca 0.33 MnO 3 . At the demagnetized and remanent state, a variation of spin-spin relaxation time T 2 , across the 55 Mn line, due to a Suhl-Nakamura interaction is observed, which suggests that the ferromagnetic metallic double exchange regions, at liquid helium temperatures, are at least 4 nm in size

  1. Infrared reflectivity investigation of the phase transition sequence in Pr{sub 0.5}Ca{sub 0.5}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J.L., E-mail: jlr@fisica.uminho.pt [Centro and Departamento de Física da Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Vieira, L.G. [Centro and Departamento de Física da Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Gomes, I.T. [Centro and Departamento de Física da Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); IFIMUP and IN - Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia da Faculdade de Ciências da Universidade do Porto, R. do Campo Alegre, 687, 4769-007 Porto (Portugal); Araújo, J.P. [IFIMUP and IN - Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia da Faculdade de Ciências da Universidade do Porto, R. do Campo Alegre, 687, 4769-007 Porto (Portugal); Tavares, P. [Centro de Química – Vila Real, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal); Almeida, B.G. [Centro and Departamento de Física da Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2016-06-15

    This work reports an infrared reflectivity study of the phase transition sequence observed in Pr{sub 0.5}Ca{sub 0.5}MnO{sub 3.} The need to measure over an extended spectral range in order to properly take into account the effects of the high frequency polaronic absorption is circumvented by adopting a simple approximate method, based on the asymmetry present in the Kramers Kronig inversion of the phonon spectrum. The temperature dependence of the phonon optical conductivity is then investigated by monitoring the behavior of three relevant spectral moments of the optical conductivity. This combined methodology allows us to disclose subtle effects of the orbital, charge and magnetic orders on the lattice dynamics of the compound. The characteristic transition temperatures inferred from the spectroscopic measurements are compared and correlated with those obtained from the temperature dependence of the induced magnetization and electrical resistivity. - Highlights: • Study of the effects of orbital, charge and spin orders on the lattice dynamics. • Phonon optical conductivity spectral moments are used to monitor phase transitions. • Precursor effects of the AFM order are detected by infrared spectroscopy.

  2. Effect of mechanical milling on the electrical and magnetic properties of nanostructured Ni0.5Zn0.5Fe2O4

    International Nuclear Information System (INIS)

    Sivakumar, N; Narayanasamy, A; Ponpandian, N; Greneche, J-M; Shinoda, K; Jeyadevan, B; Tohji, K

    2006-01-01

    Nanocrystalline Ni 0.5 Zn 0.5 Fe 2 O 4 spinel ferrite with a grain size of 50 nm was prepared by using the ceramic method. The grain size was further reduced to 14 nm by milling the as-prepared ferrite particles in a high-energy ball mill. From the impedance spectroscopy studies we have observed that the dc electrical conductivity increases upon milling. Furthermore, the cation distribution data, as obtained from the in-field Moessbauer and extended x-ray absorption fine structure measurements, suggested a decrease in the conductivity for the milled sample. The increase in conductivity of the milled sample is, therefore, attributed to conduction by the oxygen vacancies created by mechanical milling. The higher values obtained for the activation energy for conduction are also evidence for the oxygen vacancy conduction. The increase in Neel temperature from 573 to 611 K on reducing the grain size from 50 to 14 nm has been explained based on the changes in the cation distribution. The observed increase in the coercivity of the milled sample has been attributed to surface anisotropy of increasing number of ions on the surface. The Moessbauer spectra show canted spin structure for the milled samples

  3. Ce-doping effects on electronic structures of Ba0.5Sr0.5TiO3 thin film

    International Nuclear Information System (INIS)

    Wang, S Y; Cheng, B L; Wang, Can; Button, T W; Dai, S Y; Jin, K J; Lu, H B; Zhou, Y L; Chen, Z H; Yang, G Z

    2006-01-01

    In order to clarify the basic reason why Ce doping can dramatically decrease the leakage current in Ba 0.5 Sr 0.5 TiO 3 (BST) as reported in our previous work (Wang et al 2005 J. Phys. D: Appl. Phys. 38 2253), we have employed x-ray photoelectron spectroscopy (XPS) and the optical transmittance technique to study the electronic structure of undoped and 1.0 at% Ce-doped BST (CeBST) films fabricated by pulsed laser deposition. XPS results show that Ce doping has a strong influence on the valence band and core levels of BST films, and that the Fermi level is lowered by about 0.35 eV by Ce doping. Optical transmittance measurements demonstrate that the energy gap is expanded with Ce doping. These Ce-doping effects can induce an increase in the barrier height for the thermionic emission and eventually reduce leakage current in CeBST thin films

  4. Nanocrystalline (U0.5Ce0.5)O2±x solid solutions through citrate gel-combustion

    Science.gov (United States)

    Maji, D.; Ananthasivan, K.; Venkata Krishnan, R.; Balakrishnan, S.; Amirthapandian, S.; Joseph, Kitheri; Dasgupta, Arup

    2018-04-01

    Nanocrystalline powders of (U0.5Ce0.5)O2±x solid solutions were synthesized in bulk (100-200 g) through the citrate gel combustion. The fuel (citric acid) to oxidant (nitrate) mole ratio (R) was varied from 0.1 to 1.0. Two independent lots of the products obtained through the gel-combustion were calcined at 973 K in air and in a mixture of argon containing 8% H2 respectively. All these powders were characterized for their bulk density, X-ray crystallite size, specific surface area, size distribution of the particles, porosity as well as residual carbon. The morphology and microstructures of these powders were studied by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Nanocrystalline single phase fluorite solid solutions having a typical crystallite size of about (7-15 nm) were obtained. These powders were highly porous comprising cuboidal flaky agglomerates. The combustion mixture with an 'R' value of 0.25 was found to undergo volume combustion and was found to yield a product that was distinctly different. The systematic investigation on synthesis and characterization of nanocrystalline UCeO2 is reported for the first time.

  5. Band offsets and electronic structures of interface between In{sub 0.5}Ga{sub 0.5}As and InP

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Genwang [School of Physical Science and Engineering and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052 (China); College of Science, Henan University of Technology, Zhengzhou 450001 (China); Wang, Changhong; Wang, Weichao [College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071 (China); Liang, Erjun, E-mail: ejliang@zzu.edu.cn [School of Physical Science and Engineering and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052 (China)

    2016-02-07

    III–V semiconductor interfacing with high-κ gate oxide is crucial for the high mobility metal-oxide-semiconductor field transistor device. With density functional theory calculations, we explored the band offsets and electronic structures of the In{sub 0.5}Ga{sub 0.5}As/InP interfaces with various interfacial bondings. Among six different bonding interfaces, we found that P-In(Ga) bonding interface showed the highest stability. Local density of states calculations was adopted to calculate the band offsets. Except for the metallic interface, we noticed that neither valence band offset nor conduction band offset depended on the interfacial bondings. For the most stable P-In(Ga) interface, we did not observe any gap states. Furthermore, we explored the P-In(Ga) interfaces with interfacial P-As exchange defects, which slightly modified the interface stability and the band offsets but did not produce any gap states. These findings provide solid evidence that InP could serve as a promising interfacial passivation layer between III–V material and high-κ oxide in the application of high mobility devices.

  6. Complex impedance techniques and some properties of Mn sub 0.5 Zn sub 0.5 Fe sub 2 O sub 4 ferrite

    International Nuclear Information System (INIS)

    Ahmad Nazlim Yusoff; Mustaffa Abdullah

    1995-01-01

    Complex impedances (Z-axes = Z' - jZ ) of a standard parallel R-C circuit and a Mn sub 0.5 Zn sub 0.5 Fe sub 2 O sub 4 ferrite sample at 300 K have been measured in the frequency range 1 Hz to 10 MHz by a technique of phase shift. For comparison, the impedances of both systems were also measured using Schlumberger HF 1255 frequency response analyzer. The complex impedance spectrum (Z' vs Z') from the R-C circuit is a perfect semicircle, whereas the spectrum for the ferrite sample is a semicircular curve with its centre being depressed to below the real impedance axis. The depression of the semicircle for the ferrite is discussed as due to a deviation from the ideal Debye relaxation process. An equivalent circuit model that comprises of a capacitor and a resistor in parallel is suggested for the ferrite, but the result for the impedance is modified by including a factor that accounts for the distribution of the relaxation time. The simulated data from the circuit are in agreement with those from the experiment. The dispersion of the impedance is attributed to the conduction and polarization processes in the material

  7. EFFECT OF DIFFERENT COMPACTION PRESSURE AND DIFFERENT SINTERING ROUTE ON K0.5NA0.5NBO₃ PHYSICAL AND DIELECTRIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    Nor Fatin Khairah Bahanurddin

    2016-07-01

    Full Text Available Alkaline niobate known as K0.5Na0.5NbO3 (KNN, a lead-free piezoelectric ceramic was synthesized via a solid state reaction method. The samples were compacted at different pressures (100, 200, 300 and 400 MPa and sintered using two different techniques (conventional furnace and hot isostatic pressing (HIP. The effect of compaction pressure and sintering technique on physical and dielectric properties was studied. The optimum compaction pressure (300 MPa and sintering via HIP (at 1080 °C for 30 min increased the density and grain size ( range 30 - 300 nm and improved its dielectric properties. Therefore, the combination of suitable compaction pressure and sintering technique has produced larger grain size and higher density of KNN which resulted in outstanding dielectric properties. At room temperature, excellent values of ε r (5517.35 and tan δ (0.954, recorded at 1 MHz were measured for the KNN300HIP sample with highest density (4.4885 g/cm³.

  8. Frequency effects on charge ordering in Y0.5Ca0.5MnO3 by impedance spectroscopy

    Science.gov (United States)

    Sarwar, Tuba; Qamar, Afzaal; Nadeem, Muhammad

    2015-02-01

    In this work, structural and electrical properties of Y0.5Ca0.5MnO3 are investigated by employing X-ray diffraction and impedance spectroscopy, respectively. Applied ac electric field showed the charge ordering transition temperature around 265 K and below this temperature the heteromorphic behavior of the sample is discussed in the proximity of TCO. With frequency effects the volume of robust charge orbital ordering (COO) domains diminishes due to different competing phases along with Jahn Teller distortions. Comprehensive melting and collapse of charge orbital ordering occurs below TN(125 K), where a colossal drop in the value of impedance is observed. The change in profile of modulus plane plots determines the spreading of relaxation time of intermingled phases. Hopping mechanism is elaborated in terms of strong electron phonon coupling. Variable range hopping model and Arrhenius model are used to discuss the short and long range hopping between Mn3+ and Mn4+ channels assessing the activation energy Ea.

  9. TiNiSn and Zr{sub 0.5}Hf{sub 0.5}NiSn superlattices for thermoelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Tino; Jakob, Gerhard [Institut fuer Physik, Universitaet Mainz, 55099 Mainz (Germany); Schwall, Michael; Kozina, Xeniya; Balke, Benjamin; Felser, Claudia [Institut fuer Analytische und Anorganische Chemie, Universitaet Mainz, 55099 Mainz (Germany); Populoh, Sascha; Weidenkaff, Anke [EMPA, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland)

    2012-07-01

    In order to increase the attractiveness of thermoelectric devices, their efficiency must be increased. Beside others, the properties of the thermoelectric material can be improved. That can be achieved by either increasing Seebeck coefficient or conductivity or by a depressed thermal conductivity along the thermal gradient. For thin films, superlattices or multilayers can be used to lower the cross plane thermal conductivity. As a bottom up approach, artificially layered films with a periodicity of about 5-6 nm are assumed to generate the most phonon scattering at the interfaces. If electrical properties remain unchanged or less effected, the thermoelectric efficiency is enhanced. Semiconducting Half-Heuslers are well studied thermoelectric bulk materials. Among others, TiNiSn and Zr{sub 0.5}Hf{sub 0.5}NiSn are potential candidates. Essentially, their similar lattice constants enable epitaxial layers on top of each other. Furthermore, varied atomic masses of Ti, Zr and Hf generate the aspired alternating mass distribution. By rotating the substrate in between simultaneously burning cathodes, significant film thicknesses can be achieved by sputter deposition.

  10. Influence of High Magnetic Field and Zn Doping on Robust CO Phase of La0.5Ca0.5MnO3

    Science.gov (United States)

    Jin, Z.; Xia, Z. C.; Wei, M.; Yang, F.; Huang, S.; Xiao, G. L.; Shang, C.; Cheng, H.; Wu, H.; Zhang, X. X.; Ouyang, Z. W.

    2017-08-01

    Magnetic and electrical transport properties of La0.5Ca0.5- x Zn x MnO3 ( x = 0, 0.1, 0.15) have been investigated in a wide magnetic field range from 0 T to 50 T. Experimental results show that doping of nonmagnetic Zn2+ ion at Ca site and application of high magnetic field had obvious tuning effects on the stability of the robust charge-order phase, inducing new magnetization and electrical transport behaviors. In particular, obvious temperature and field hysteresis was induced, leading to enhanced magnetoresistance at around room temperature. Based on the intricate interplay between the external magnetic field and chemical strain (lattice distortion) induced by the dopant, which changed the bond length and the angle of double exchange and partially destroyed the charge-order phase, a weak ferromagnetic phase formed. The hysteretic behavior and enhanced magnetoresistance can be understood based on the tuning effects of the high magnetic field and dopant on the stability of the charge-order phase.

  11. Parallel charge sheets of electron liquid and gas in La0.5Sr0.5TiO3/SrTiO3 heterostructures

    Science.gov (United States)

    Renshaw Wang, X.; Sun, L.; Huang, Z.; Lü, W. M.; Motapothula, M.; Annadi, A.; Liu, Z. Q.; Zeng, S. W.; Venkatesan, T.; Ariando

    2015-12-01

    We show here a new phenomenon in La0.5Sr0.5TiO3/SrTiO3 (LSTO/STO) heterostructures; that is a coexistence of three-dimensional electron liquid (3DEL) and 2D electron gas (2DEG), separated by an intervening insulating LSTO layer. The two types of carriers were revealed through multi-channel analysis of the evolution of nonlinear Hall effect as a function of film thickness, temperature and back gate voltage. We demonstrate that the 3D electron originates from La doping in LSTO film and the 2D electron at the surface of STO is due to the polar field in the intervening insulating layer. As the film thickness is reduced below a critical thickness of 6 unit cells (uc), an abrupt metal-to-insulator transition (MIT) occurs without an intermediate semiconducting state. The properties of the LSTO layer grown on different substrates suggest that the insulating phase of the intervening layer is a result of interface strain induced by the lattice mismatch between the film and substrate. Further, by fitting the magnetoresistance (MR) curves, the 6 unit cell thick LSTO is shown to exhibit spin-orbital coupling. These observations point to new functionalities, in addition to magnetism and superconductivity in STO-based systems, which could be exploited in a multifunctional context.

  12. Tunneling current in HfO2 and Hf0.5Zr0.5O2-based ferroelectric tunnel junction

    Science.gov (United States)

    Dong, Zhipeng; Cao, Xi; Wu, Tong; Guo, Jing

    2018-03-01

    Ferroelectric tunnel junctions (FTJs) have been intensively explored for future low power data storage and information processing applications. Among various ferroelectric (FE) materials studied, HfO2 and H0.5Zr0.5O2 (HZO) have the advantage of CMOS process compatibility. The validity of the simple effective mass approximation, for describing the tunneling process in these materials, is examined by computing the complex band structure from ab initio simulations. The results show that the simple effective mass approximation is insufficient to describe the tunneling current in HfO2 and HZO materials, and quantitative accurate descriptions of the complex band structures are indispensable for calculation of the tunneling current. A compact k . p Hamiltonian is parameterized to and validated by ab initio complex band structures, which provides a method for efficiently and accurately computing the tunneling current in HfO2 and HZO. The device characteristics of a metal/FE/metal structure and a metal/FE/semiconductor (M-F-S) structure are investigated by using the non-equilibrium Green's function formalism with the parameterized effective Hamiltonian. The result shows that the M-F-S structure offers a larger resistance window due to an extra barrier in the semiconductor region at off-state. A FTJ utilizing M-F-S structure is beneficial for memory design.

  13. Preparation and piezoelectric properties of (K0.5Na0.5)NbO3 lead-free piezoelectric ceramics with pressure-less sintering

    International Nuclear Information System (INIS)

    Du Hongliang; Li Zhimin; Tang Fusheng; Qu Shaobo; Pei Zhibin; Zhou Wancheng

    2006-01-01

    Lead-free piezoelectric ceramics (K 0.5 Na 0.5 )NbO 3 (abbreviated as KNN) with the relative density of 97.6% have been synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics with different sintering temperature and heating rate was analyzed. Results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of heating rate and sintering temperature on microstructure and piezoelectric properties of KNN ceramics was investigated. The densification behavior and piezoelectric properties of KNN ceramics were enhanced by improving heating rate and sintering temperature. Pure KNN ceramics sintered at 1120 deg. C with heating rate of 5 deg. C/min showed optimized densification and piezoelectric properties (ρ = 4.4 g/cm 3 , d 33 = 120 pC/N -1 , k p = 0.40 and T c = 400 deg. C). The results show that KNN is a promising candidate for lead-free piezoelectric ceramics

  14. Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La0.5Ca0.5MnO3 nanoparticles

    International Nuclear Information System (INIS)

    Iniama, G.; Ita, B. I.; Presa, P. de la; Hernando, A.; Alonso, J. M.; Multigner, M.; Cortés-Gil, R.; Ruiz-González, M. L.; Gonzalez-Calbet, J. M.

    2014-01-01

    In this paper, the physical properties of half-doped manganite La 0.5 Ca 0.5 MnO 3 with crystallite sizes ranging from 15 to 40 nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15 nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22 nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15 nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.

  15. Low temperature magnetic studies on PbFe{sub 0.5}Nb{sub 0.5}O{sub 3} multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Matteppanavar, Shidaling [Department of Physics, Bangalore University, Jnanabharati Campus, Bangalore 560056 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, Bangalore University, Jnanabharati Campus, Bangalore 560056 (India); Rayaprol, Sudhindra [UGC–DAE CSR, Mumbai Centre, B.A.R.C, R-5 Shed, Mumbai 400085 (India)

    2014-09-01

    PbFe{sub 0.5}Nb{sub 0.5}O{sub 3} (PFN), a well-known A(B′{sub 1/2}B″{sub 1/2})O{sub 3} type multiferroic, was successfully synthesized in single phase by a single step solid state reaction method. The single phase PFN was characterized through XRD, microstructure through SEM, and magnetic studies were carried out through a temperature dependent vibrating sample magnetometer (VSM) and neutron diffraction (ND) measurements. PFN exhibits a cusp at around 150 K in the temperature dependent magnetic susceptibility corresponding to the Néel temperature (T{sub N1}) and another peak around 10 K (T{sub N2}) corresponding to spin-glass like transition. In the temperature dependent ND studies, a magnetic Bragg peak appears at Q=1.35 Å{sup −1} (where Q=4πsinθ/λ, is called the scattering vector) below T{sub N} (150 K) implying antiferromagnetic (AFM) ordering in the system. On the basis of Rietveld analysis of the ND data at T=2 K, the magnetic structure of PFN could be explained by a G-type antiferromagnetic structure.

  16. Volume of Anesthetic in 0.5% Marcaine with 1:200,000 Epinephrine Dental Carpule

    Science.gov (United States)

    2016-04-01

    copyrighted material in the thesis manuscript entitled: "Volume of Anesthetic in 0.5% Marcaine with 1:200,000 Epinephrine Dental Carpule" Is...3. School/DepartmenUCenter: Army Postgraduate Dental School, AEGD-2 Program, Fort Hood, TX 4. Phone: (708) 227-2152 5. Type of clearance...X_Thesis _Article _Book _Poster _Presentation _Other 6. Title: "Volume of Anesthetic in 0.5% Marcaine with 1:200,000 Epinephrine Dental Carpule

  17. Crystal and magnetic study of the disordered perovskites Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} and Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Retuerto, M., E-mail: mretuerto@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Martinez-Lope, M.J.; Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Munoz, A. [Departamento de Fisica Aplicada, EPS, Universidad Carlos III, Avda. Universidad 30, E-28911 Leganes-Madrid (Spain); Fernandez-Diaz, M.T. [Institut Max Von Laue Paul Langevin, F-38042 Grenoble (France); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain)

    2010-10-15

    We have investigated the double perovskites Ca{sub 2}MSbO{sub 6} (M = Mn, Fe) that have been prepared by solid-state reaction (M = Fe) and wet chemistry procedures (M = Mn). The crystal and magnetic structures have been studied from X-ray (XRD) and neutron powder diffraction (NPD) data. Rietveld refinements show that the crystal structures are orthorhombic (space group Pbnm) with complete disorder of M and Sb cations, so the formula should be rewritten as Ca(M{sub 0.5}Sb{sub 0.5})O{sub 3}. Due to this disorder no evidences of Jahn-Teller distortion can be observed in the MnO{sub 6} octahedra of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3}, in contrast with the ordered double perovskite Sr{sub 2}MnSbO{sub 6}. Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3} behaves as an antiferromagnet with an ordered magnetic moment for Fe{sup 3+} of 1.53(4){mu}{sub B} and a propagation vector k = 0, as investigated by low-temperature NPD. The antiferromagnetic ordering is a result of the high degree of Fe/Sb anti-site disorder of the sample, which originates the spontaneous formation of Fe-rich islands, characterized by the presence of strong Fe-O-Fe antiferromagnetic couplings with enough long-range coherence to produce a magnetic contribution perceptible by NPD. By contrast, the magnetic structure of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} cannot be observed by low-temperature NPD because the magnitude of the ordered magnetic moments is below the detection threshold for neutrons.

  18. Phase transition in metastable perovskite Pb(AlNb)0,5O3

    International Nuclear Information System (INIS)

    Zhabko, T.E.; Olekhnovich, N.M.; Shilin, A.D.

    1987-01-01

    Dielectric properties of metastable perovskite Pb(AlNb) 0.5 O 3 and X-ray temperature investigations of both perovskite and pyrochlore modifications of the given compound are studied. Samples with the perovskite structure are prepared from the pyrochlorephase at 4-5 GPa pressure and 1170-1270 K. Ferroelectric phase transition is shown to occur in the metastable perovskite phase Pb(AlNb) 0.5 O 3 at 170 K

  19. Dielectric and Ferroelectric Properties of SrTiO3-Bi0.5Na0.5TiO3-BaAl0.5Nb0.5O3 Lead-Free Ceramics for High-Energy-Storage Applications.

    Science.gov (United States)

    Yan, Fei; Yang, Haibo; Lin, Ying; Wang, Tong

    2017-11-06

    Pulsed capacitors require high-recoverable energy-storage density (W rec ) and high energy-storage efficiency (η), which can be realized through the selection and adjustment of the composition. In this work, (1 - x)SrTiO 3 -x(0.95Bi 0.5 Na 0.5 TiO 3 -0.05BaAl 0.5 Nb 0.5 O 3 ) [(1 - x)ST-x(BNT-BAN)] ceramics were successfully prepared via the pressureless solid-state reaction method. The dielectric constant increases gradually with the introduction of BNT-BAN and obtains a maximum value of 3430 with the composition of 0.4ST-0.6(BNT-BAN) at 100 Hz, which is 10.39 times higher than that of the pure ST sample (∼330). Dispersive relaxor behaviors and ferroelectric performances can be enhanced with the introduction of BNT-BAN. The composition of 0.5ST-0.5(BNT-BAN) exhibits a high W rec of 1.89 J/cm 3 as well as a high η of 77%. Therefore, the (1 - x)ST-x(BNT-BAN) systems are candidate materials for pulsed capacitor applications.

  20. Effect of Ba addition on the structural, dielectric and ferroelectric properties of Na0.5Bi0.5TiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Suchanicz J.

    2015-06-01

    Full Text Available Lead-free (Na0.5Bi0.51-xBaxTiO3 (x = 0, 0.04 and 0.06 ceramics were fabricated by conventional solid phase sintering process. X-ray diffraction analysis shows that obtained specimens possess the perovskite structure. The microstructure study shows a dense structure, in good agreement with the relative density determined by the Archimedes method (above 95 %. Electric permittivity anomaly is shifted to low temperature after Ba doping of NBT. The pyroelectric and hysteresis loops measurements show that polarization and coercive field increases and decreases, respectively, after Ba doping of NBT. The obtained results are discussed in terms of ions/lattice imperfections, which create local electromechanical fields. The investigated ceramics are considered to be promising candidates for lead-free electronic materials.

  1. Band gap modification and ferroelectric properties of Bi0.5(Na,K0.5TiO3-based by Li substitution

    Directory of Open Access Journals (Sweden)

    Ngo Duc Quan

    2014-01-01

    Full Text Available We report on the reduction of band gap in Bi0.5(Na0.82-xLixK0.180.5(Ti0.95Sn0.05O3 from 2.99 eV to 2.84 eV due to the substitutions of Li+ ions to Na+ sites. In addition, the lithium substitution samples exhibit an increasing of the maximal polarizations from 21.8 to 25.7 μC/cm2. The polarization enhancement of ferroelectric and reduction of the band gaps are strongly related to the Li substitution concentration as evaluated via the electronegative between A-site and oxygen and tolerance factor. The results are promising for photovoltaic and photocatalytic applications.

  2. Desarrollo y optimización de una jalea de piroxicam 0,5 % Development and optimization related to a 0.5 % Piroxican jelly

    Directory of Open Access Journals (Sweden)

    Oscar García Pulpeiro

    2009-12-01

    Full Text Available Se desarrolló por primera vez en Cuba, una formulación de jalea de piroxicam al 0,5 %. Se tomó como referencia la composición de la formulación líder del mercado FELDENE GELâ, a la cual se le efectuaron algunas modificaciones. Se realizaron 4 experimentos en las evaluaciones preliminares que sirvieron de base para la etapa posterior de diseño y optimización de la formulación. Se aplicó un diseño de experimentos con mezcla, para lo cual se emplearon como variables independientes la concentración de Carbopol 940, trietanolamina y hidroxipropilmetilcelulosa. Se evaluó la influencia de estos componentes en el pH, el área de extensibilidad y en algunas propiedades organolépticas. A partir de estos resultados, se seleccionó una formulación óptima.For the first time in Cuba a 0.5 % Piroxican jelly formula was developed. The point of reference was the leader formula from FELEDENE GELâ; market which underwent some modifications. During first assessments four experiments were carried out as basis for the later stage of formula design and optimization. An experimental design with mixture was applied using as independent variables the concentration of Carbopol 940, Trietanolamine, and Hidroxypropyl methylcellulose. Influence of these components on pH, the extensibility area, and on some organoleptic properties. From these results, an optimal formula was selected.

  3. Understanding the influence of surface chemical states on the dielectric tunability of sputtered Ba0.5Sr0.5TiO3 thin films

    International Nuclear Information System (INIS)

    Venkata Saravanan, K; James Raju, K C

    2014-01-01

    The surface chemical states of RF-magnetron sputtered Ba 0.5 Sr 0.5 TiO 3 (BST5) thin films deposited at different oxygen mixing percentage (OMP) was examined by x-ray photoelectron spectroscopy. The O1s XPS spectra indicate the existence of three kinds of oxygen species (dissociated oxygen ion O 2 − , adsorbed oxide ion O − and lattice oxide ion O 2− ) on the films’ surface, which strongly depends on OMP. The presence of oxygen species other than lattice oxygen ion makes the films’ surface highly reactivity to atmospheric gases, resulting in the formation of undesired surface layers. The XPS results confirm the formation of surface nitrates for the films deposited under oxygen deficient atmosphere (OMP not ≦ 25%), whereas the films deposited in oxygen rich atmosphere (OMP not ≧ 75%) show the presence of metal-hydroxide. The influence of a surface dead layer on the tunable dielectric properties of BST5 films have been studied in detail and are reported. Furthermore, our observations indicate that an optimum ratio of Ar:O 2 is essential for achieving desired material and dielectric properties in BST5 thin films. The films deposited at 50% OMP have the highest dielectric tunability of ∼65% (@280 kV cm −1 ), with good ϵ r -E curve symmetry of 98% and low tan δ of 0.018. The figure of merit for these films is about 35, which is promising for frequency agile device applications. (papers)

  4. Cycloplegic Refraction in Hyperopic Children: Effectiveness of a 0.5% Tropicamide and 0.5% Phenylephrine Addition to 1% Cyclopentolate Regimen.

    Science.gov (United States)

    Yoo, Seul Gi; Cho, Myung Jin; Kim, Ungsoo Samuel; Baek, Seung Hee

    2017-06-01

    To evaluate the effectiveness of a cycloplegic regimen using 0.5% tropicamide and 0.5% phenylephrine (Tropherine, Hanmi Pharm), in addition to 1% cyclopentolate, in hyperopic children. The medical records of hyperopic patients below the age of 14 years who had undergone cycloplegic retinoscopy were retrospectively reviewed. Cycloplegic refractions were performed using one of two cycloplegic regimens. Regimen 1 was a Tropherine-added regimen comprising the administration of one drop of 1% cyclopentolate followed by two to three drops of Tropherine added at 15-minute intervals. Regimen 2 was a cyclopentolate-only regimen comprising the administration of three to four drops of 1% cyclopentolate at 15-minute intervals. The mean difference between noncycloplegic and cycloplegic refraction was compared between the two regimens. A total of 308 eyes of 308 hyperopic children were included. The mean difference (±standard deviation) in the spherical equivalent (SE) between cycloplegic and noncycloplegic refraction was significantly larger in regimen 2 than in regimen 1, with values of +1.70 ± 1.03 diopters (D) and +1.25 ± 0.89 D, respectively (p=0.001). The SE change after cycloplegia was significantly different between the two regimens only in patients aged 5 years or younger (p=0.001), particularly in those with high hyperopia with an SE ≥5 D (p=0.005) or fully accommodative esotropia (p=0.009). There was no significant difference between the two regimens in patients older than 5 years, regardless of the presence of high hyperopia or fully accommodative esotropia. The Tropherine-added regimen exerted a weaker cycloplegic effect than the cyclopentolate-only regimen, particularly in children under the age of 5 years with high hyperopia or fully accommodative esotropia. However, the difference in refraction between the two regimens was small. A Tropherine-added regimen can be effective in hyperopic children, with less associated discomfort than the instillation of

  5. Effects of strain on the magnetic and transport properties of the epitaxial La0.5Ca0.5MnO3 thin films

    Science.gov (United States)

    Zarifi, M.; Kameli, P.; Ehsani, M. H.; Ahmadvand, H.; Salamati, H.

    2016-12-01

    The epitaxial strain can considerably modify the physical properties of thin films compared to the bulk. This paper reports the effects of substrate-induced strain on La0.5Ca0.5MnO3 (LCMO) thin films, grown on (100) SrTiO3 (STO) and LaAlO3 (LAO) substrates by pulsed laser deposition technique. Transport and magnetic properties were found to be strongly dependent on strain type. It is also shown that compressive (tensile) strain leads to the increase (decrease) in the magnetization of the films. Moreover, it was observed that all LCMO films deposited on both LAO and STO substrates behave as an insulator, but LCMO/LAO thin films with compressive strain have lower resistivity than LCMO/STO thin films with tensile strain. Applying magnetic field to LCMO/STO thin films with thickness of 25 and 50 nm leads to very small change in the resistivity, while the effects of magnetic field on the sample with thickness of 125 nm leads to an insulator-metal transition. For LCMO/LAO thin films, the magnetic field has a strong impact on the resistivity of samples. The results show that the magnetoresistance (MR) is enhanced by increasing film thickness for LCMO/LAO samples, due to the relatively stronger phase separation. For LCMO/STO thin films MR is drastically decreased by reduction of film thickness, which is attributed to the enhancement of the charge-orbital order (CO-O) accompanying the complex spin order (the so-called CE type). The changes of the antiferromagnetic structure from the CE to C type and the enhancement of the CE type could be attributed to the in-plane compressive and tensile strain, respectively.

  6. Infratentorial brain maturation: a comparison of MRI at 0.5 and 1.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Hittmair, K. [MR Institute, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Kramer, J. [MR Institute, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Rand, T. [Department of Diagnostic Radiology, University of Vienna, Vienna (Austria); Bernert, G. [Department of Paediatrics, University of Vienna, Vienna (Austria); Wimberger, D. [Department of Diagnostic Radiology, University of Vienna, Vienna (Austria)

    1996-05-01

    Our purpose was to establish parameters for normal infratentorial brain maturation at 0.5 and 1.5 T and to evaluate the field strength criteria for the assessment of infratentorial brain maturation with MRI. We examined 27 children with normal psychomotor development (3 days to 24 months) with a 1.5 T system and 22 (4 days to 29 months) with a 0.5 T system; standard T2-weighted spin-echo sequences (TR/TE 2 500/90 ms at 1.5 T and TR/TE 2 200/90 ms at 0.5 T) were obtained. The signal intensity of infratentorial anatomical structures compared to their surroundings was classified as high, isointense or low by three neuroradiologists. For anatomical structures with age-related contrast changes, the time of these changes was determined statistically for the 0.5 T and 1.5 T system independently. The delineation of the structures without age-related contrast changes at the two field strengths was compared using a {chi} {sup 2} test. Age-related contrast changed were found in the same anatomical structures (``marker sites``) at 0.5 and 1.5 T. Generally, these changes were apparent in larger structures (pons, middle cerebellar peduncles, medulla, cerebellar folia, red nuclei, cerebral peduncles), with only slight field-strength-dependent differences in the time of the contrast changes. Contrast changes from high to isointense signal were observed slightly earlier at 0.5 T and changes from isointense to low signal slightly later at 0.5 T. The delineation of the smaller anatomical structures was significantly better at 1.5 T but these structures did not show age-related contrast changes. The differences in the assessment of infratentorial brian maturation between 0.5 and 1.5 T can be attributed to a lower signal-to-noise ratio at lower magnetic field strengths. These differences do not complicate temporal classification of the stage of infratentorial brain maturation using the same ``marker sites`` and the same temporal criteria at 0.5 or 1.5 T. (orig.). With 4 figs., 2 tabs.

  7. Infratentorial brain maturation: a comparison of MRI at 0.5 and 1.5 T

    International Nuclear Information System (INIS)

    Hittmair, K.; Kramer, J.; Rand, T.; Bernert, G.; Wimberger, D.

    1996-01-01

    Our purpose was to establish parameters for normal infratentorial brain maturation at 0.5 and 1.5 T and to evaluate the field strength criteria for the assessment of infratentorial brain maturation with MRI. We examined 27 children with normal psychomotor development (3 days to 24 months) with a 1.5 T system and 22 (4 days to 29 months) with a 0.5 T system; standard T2-weighted spin-echo sequences (TR/TE 2 500/90 ms at 1.5 T and TR/TE 2 200/90 ms at 0.5 T) were obtained. The signal intensity of infratentorial anatomical structures compared to their surroundings was classified as high, isointense or low by three neuroradiologists. For anatomical structures with age-related contrast changes, the time of these changes was determined statistically for the 0.5 T and 1.5 T system independently. The delineation of the structures without age-related contrast changes at the two field strengths was compared using a χ 2 test. Age-related contrast changed were found in the same anatomical structures (''marker sites'') at 0.5 and 1.5 T. Generally, these changes were apparent in larger structures (pons, middle cerebellar peduncles, medulla, cerebellar folia, red nuclei, cerebral peduncles), with only slight field-strength-dependent differences in the time of the contrast changes. Contrast changes from high to isointense signal were observed slightly earlier at 0.5 T and changes from isointense to low signal slightly later at 0.5 T. The delineation of the smaller anatomical structures was significantly better at 1.5 T but these structures did not show age-related contrast changes. The differences in the assessment of infratentorial brian maturation between 0.5 and 1.5 T can be attributed to a lower signal-to-noise ratio at lower magnetic field strengths. These differences do not complicate temporal classification of the stage of infratentorial brain maturation using the same ''marker sites'' and the same temporal criteria at 0.5 or 1.5 T. (orig.). With 4 figs., 2 tabs

  8. La transición de fase I4/mcm→Pm3m en Sr0.5Ba0.5HfO3-δ

    Directory of Open Access Journals (Sweden)

    Lamas, D.

    2001-08-01

    Full Text Available The effect of partial substitution of cations in AMO3 compounds have been studied because the physical properties and applications of these materials can be improved. In particular we are interested in the Sr1-xBaxHfO3 family. In SrHfO3 the phase transition to cubic structure has been observed to occur when the angle between two consecutive oxygen octahedra tends to zero. Instead in BaHfO3 no phase transition was observed. These facts were attributed to depend on the atomic radius of A cation. In this contribution the study of Sr0.5Ba0.5HfO3 oxide is shown. The compound was prepared by the high temperature solid state reaction method and analyzed by X-ray diffraction and Perturbed Angular Correlation (PAC Spectroscopy at different temperatures. Diffraction studies revealed that about 400-420º C a structural phase transition from I4/mcm to Pm3m occurred by tending to zero the rotation angle. By PAC this transition was also observed. In the cubic phase the electric field gradient EFG measured were produced by defects. The same model applied to interpreted the results of BaTi1-xHfxO3 and the atomic positions determined by X-ray diffraction were used. This calculation reproduces reasonably the temperature dependence of the EFG measured by PAC.Los AMO3, llamados perovskitas, forman una gran familia de compuestos que presentan a su vez diversas propiedades físicas así como enormes aplicaciones tecnológicas. Es posible expandir esta familia y sus propiedades y aplicaciones, sustituyendo los cationes Ay M originales por diferentes A’ y M’. En este trabajo presentamos el estudio del compuesto Sr1-xBaxHfO3 con x=0.5. El óxido fue preparado por el método de reacción en fase sólida. La muestra fue analizada por difracción de Rayos X y por espectroscopía de Correlaciones Angulares Perturbadas (PAC a diferentes temperaturas. El estudio cristalográfico del material reveló que entre 400 y 420ºC se produce la transición de fase de estructura I4

  9. Mass transport in Ti0.5Sb2Te3 phase-change nanobridge

    International Nuclear Information System (INIS)

    Ji, Xinglong; Wu, Liangcai; Lv, Shilong; Rao, Feng; Zhu, Min; Song, Zhitang; Zhou, Xilin; Feng, Songlin

    2014-01-01

    Investigation of atomic migration behavior in nanoscale phase-change material is very valuable for phase-change memory applications. In this work, Ti 0.5 Sb 2 Te 3 -based phase-change nanobridges were fabricated and mass transport by atomic migration was studied. A 3-D finite-element simulation on the electrothermal field was introduced to describe the electrothermal environment in the phase-change region. During the nanosecond operation, an obvious compositional distribution resulting from atomic migration was observed in the Ti 0.5 Sb 2 Te 3 phase-change nanobridge. Based on the mass continuity equation, a physical model for mass transport is proposed to illustrate that the density variation during the amorphous-to-crystalline structural transformation is the main reason for the atomic migration in nanoscale Ti 0.5 Sb 2 Te 3 phase-change material

  10. Aqueous Humor Antimicrobial Activity: In Vitro Analysis after Topical 0.5% Chloramphenicol Application.

    Science.gov (United States)

    Cagini, Carlo; Dragoni, Annalisa; Orsolini, Giampaolo; Fiore, Tito; Beccasio, Alfredo; Spadea, Leopoldo; Moretti, Amedeo; Mencacci, Antonella

    2017-06-01

    To assess aqueous humor antimicrobial activity in vitro after topical 0.5% chloramphenicol application. This investigation included 63 eyes from 65 cataract surgery patients. The study group of 48 eyes received preoperatively four topical applications of 0.5% chloramphenicol. The control group of 15 eyes was given no topical applications. Aqueous humor samples were collected for in vitro antimicrobial analysis using Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Pasteurella multocida organisms by means of disk diffusion test. No inhibition halo was observed around all aqueous humor samples from all chloramphenicol-treated patients, irrespective of the sample quantity added to the paper disks, with no significant difference from aqueous humor from untreated control patients. Aqueous humor displayed no bactericidal effect against any of the microorganisms evaluated after topical 0.5% chloramphenicol application.

  11. Raman, dielectric and variable range hopping nature of Gd2O3-doped K0.5N0.5NbO3 piezoelectric ceramics

    Directory of Open Access Journals (Sweden)

    Mahesh Peddigari

    2015-10-01

    Full Text Available (K0.5Na0.5NbO3 (KNN + x wt% Gd2O3 (x = 0 -1.5 ceramics have been prepared by conventional solid state reaction method. The effect of Gd2O3 on the structural, microstructural and dielectric properties of KNN ceramics were studied systematically. The effect of Gd2O3 on phase transformation from orthorhombic to psuedocubic structure is explained interms of changes in the internal vibration modes of NbO6 octahedra. The Raman intensity of the stretching mode v1 enhanced and shifted toward higher wavenumber with Gd2O3 concentration, which is attributed to the increase in polarizability and change in the O-Nb-O bond angles. Microstructural analysis revealed that the grain size of the KNN ceramics decreases from 2.26 ± 1.07 μm to 0.35 ± 0.13 μm and becomes homogenous with an increase in Gd2O3 concentration. The frequency dependent dielectric spectra are analyzed by using Havriliak-Negami function. The fitted symmetry parameter and relaxation time (τ are found to be 0.914 and 8.78 × 10−10 ± 5.5 × 10−11 s, respectively for the sample doped with x = 1.0. The addition of Gd2O3 to the KNN shifted the polymorphic phase transition orthorhombic to tetragonal transition temperature (TO-T from 199oC to 85oC with enhanced dielectric permittivity (ε′ = 1139 at 1 MHz. The sample with x = 1.0, shown a high dielectric permittivity (ε′ = 879 and low dielectric loss (<5% in the broad temperature range (-140oC – 150oC with the Curie temperature 307 oC can have the potential for high temperature piezoelectric and tunable RF circuit applications. The temperature dependent AC-conductivity follows the variable range hopping conduction mechanism by obtaining the slope -0.25 from the ln[ln(ρac] versus ln(T graph in the temperature range of 133 K-308 K. The effect of Gd2O3 on the Mott’s parameters such as density of states (N(EF, hopping length (RH, and hopping energy (WH have been discussed.

  12. An ultrasonic therapeutic transducers using lead-free Na0.5K0.5NbO3-CuNb2O6 ceramics

    International Nuclear Information System (INIS)

    Yang, Ming-Ru; Chu, Sheng-Yuan; Tsai, Cheng-Che

    2010-01-01

    Research highlights: → In this paper, CN was added to NKN ceramics to decrease the sintering temperature and to improve the density and piezoelectric characteristics. The influence of CuNb 2 O 6 (CN) content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized samples was investigated. Results show that the samples synthesized with CN-doped not only improved the density but also exhibited superior piezoelectric characteristic, temperature stability of resonance frequency (TCF), and elastic stiffness coefficient than those of pure NKN piezoelectric ceramics. → The bulk density (4.47 g/cm 3 ), k p (40%), k t (45%), Q m (1642), C 33 D (19.64 x 10 10 N/m 2 ), TCF (-0.011%/ o C) and TCC (0.135%/ o C) values for NKN-01CN ceramics obtained from experiments show excellent 'hard' piezoelectric properties. Furthermore, a lead-free NKN-01CN ultrasonic therapeutic transducer was successfully driven by a self-tuning circuit. - Abstract: In this work, we reports on the CuNb 2 O 6 (CN) modified lead-free Na 0.5 K 0.5 NbO 3 (NKN) based piezoelectric ceramics were synthesized by solid-state reaction methods and sintered at 1075 o C for 3 h. A secondary phase of K 4 CuNb 8 O 23 was found in the XRD pattern of NKN-based ceramics as the CN dopants is 1 mol%. Microstructural analyses of un-doped and CN-doped ceramics were performed in a scanning electron microscope. The influence of CN content on the microstructure, electrical properties, temperature stability, and mechanical properties of the synthesized ceramics was investigated. The results show that the synthesized ceramics with CN-doped not only had improved density but also exhibited superior piezoelectric characteristics, temperature stability of resonance frequency (TCF), and a better elastic stiffness coefficient than those of pure NKN piezoelectric ceramics. The bulk density (4.47 g/cm 3 ), k p (40%), k t (45%), Q m (1642), C 33 D (19.64 x 10 10 N/m 2 ), TCF (-0

  13. Redox Kinetics and Nonstoichiometry of Ce0.5Zr0.5O2−δ for Water Splitting and Hydrogen Production

    KAUST Repository

    Zhao, Zhenlong

    2017-04-25

    Water splitting and chemical fuel production as a promising carbon-neutral energy solution relies critically on an efficient electrochemical process over catalyst surfaces. The fundamentals within the surface redox pathways, including the complex interactions of mobile ions and electrons between the bulk and the surface, along with the role of adsorbates and electrostatic fields remain yet to be understood quantitatively. This work presents a detailed kinetics study and nonstoichiometry characterization of Ce0.5Zr0.5O2−δ (CZO), one of the most recognized catalysts for water splitting. The use of CZO leads to >60% improvement in the kinetic rates as compared with undoped ceria with twice the total yield at 700 °C, resulting from the improved reducibility. The peak H2 production rate is 95 μmol g–1 s–1 at 700 °C, and the total production is 750 μmol g–1. A threshold temperature of 650 °C is required to achieve significant H2 production at fast rates. The redox kinetics is modeled using two-step surface chemistry with bulk-to-surface transport equilibrium. Kinetics and equilibrium parameters are extracted, and the model predictions show good agreement with the measurements. The enthalpy of bulk defect formation for CZO is found to be 262 kJ/mol, >40% lower than that of undoped ceria. As oxygen vacancy is gradually filled up, the surface H2O splitting chemistry undergoes a transition from exothermic to endothermic, with the crossover around δ = 0.04 to 0.05, which constrains the further ion incorporation process. Our kinetics study reveals that the H2O splitting process with CZO is kinetics limited at low temperature and transitions to partial-equilibrium with significantly enhanced backward reaction at high temperature. The charge-transfer step is found to be the rate-limiting step for H2O splitting. The detailed kinetics and nonstoichiometric equilibria should be helpful in guiding the design and optimization of CZO as a catalyst, oxygen storage

  14. The effects of Na on high pressure phases of CuIn0.5Ga0.5Se2 from ab initio calculation

    International Nuclear Information System (INIS)

    Pluengphon, P; Bovornratanaraks, T; Pinsook, U; Vannarat, S

    2012-01-01

    The effects of Na atoms on high pressure structural phase transitions of CuIn 0.5 Ga 0.5 Se 2 (CIGS) were studied by an ab initio method using density functional theory. At ambient pressure, CIGS is known to have chalcopyrite (I 4-bar 2 d) structure. The high pressure phase transitions of CIGS were proposed to be the same as the order in the CuInSe 2 phase transitions which are I 4-bar 2 d→F m 3-bar m→C m c m structures. By using the mixture atoms method, the Na concentration in CIGS was studied at 0.1, 1.0 and 6.25%. The positive mixing enthalpy of Na at In/Ga sites (Na InGa ) is higher than that of Na at Cu sites (Na Cu ). It confirmed previous studies that Na preferably substitutes on the Cu sites more than the (In, Ga) sites. From the energy-volume curves, we found that the effect of the Na substitutes is to reduce the hardness of CIGS under high pressure. The most significant effects occur at 6.25% Na. We also found that the electronic density of states of CIGS near the valence band maximum is increased noticeably in the chalcopyrite phase. The band gap is close in the cubic and orthorhombic phases. Also, the Na Cu -Se bond length in the chalcopyrite phase is significantly reduced at 6.25% Na, compared with the pure Cu-Se bond length. Consequently, the energy band gap in this phase is wider than in pure CIGS, and the gap increased at the rate of 31 meV GPa -1 under pressure. The Na has a small effect on the transition pressure. The path of transformation from the cubic to orthorhombic phase was derived. The Cu-Se plane in the cubic phase displaced relatively parallel to the (In, Ga)-Se plane by 18% in order to transform to the Cmcm phase. The enthalpy barrier is 0.020 eV/atom, which is equivalent to a thermal energy of 248 K. We predicted that F m 3-bar m and Cmcm can coexist in some pressure range. (paper)

  15. High energy storage property and breakdown strength of Bi{sub 0.5}(Na{sub 0.82}K{sub 0.18}){sub 0.5}TiO{sub 3} ceramics modified by (Al{sub 0.5}Nb{sub 0.5}){sup 4+} complex-ion

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yangyang [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Xu, Jiwen, E-mail: csuxjw@126.com [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Experiment Center of Information Science, Guilin 541004 (China); Yang, Ling; Zhou, Changrong [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); Guangxi Experiment Center of Information Science, Guilin 541004 (China); Lu, Xiaopeng; Yuan, Changlai; Li, Qingning; Chen, Guohua; Wang, Hua [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

    2016-05-05

    The influence of B-site (Al{sub 0.5}Nb{sub 0.5}){sup 4+} complex-ion substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy-storage properties of Bi{sub 0.5}(Na{sub 0.82}K{sub 0.18}){sub 0.5}Ti{sub 1–x}(Al{sub 0.5}Nb{sub 0.5}){sub x}O{sub 3} (BNKT-xAN) ceramics were systematically investigated. BNKT-xAN ceramics showed single-phase perovskite structure without an obvious phase transition after adding AN. Compact and uniform microstructure with almost the same grain morphology and size was obtained. The AN doping produced slimmer P-E loops and thus improved energy storage property. Meanwhile, the energy storage density increases drastically, and a maximum value of 1.41 J/cm{sup 3} at 105 kV/cm was achieved in BNKT-0.08AN through increasing greatly its breakdown strength with more AN content. The temperature dependence of dielectric constant and dielectric loss of BNKT-xAN ceramics illustrated the obvious relaxor phase transition characteristics. Low ionic conductivity and electronic conductivity indicated the BNKT-xAN ceramics have excellent dielectric properties. These results indicated that the BNKT-AN system may be a promising lead-free material for high energy storage density capacitor. - Highlights: • The (Al{sub 0.5}Nb{sub 0.5}){sup 4+} B-site complex ions were introduced into BNT-BKT system. • The P-E loops were pinched and the P{sub r} and E{sub c} were decreased by complex ions. • Impedance spectrum revealed excellent dielectric property of complex-ion modified BNT-BNK. • Breakdown strength of BNT-BKT was enhanced by complex ions. • The energy storage density was improved to 1.41 J/cm{sup 3} by complex ions.

  16. Structural, Electrical and Magnetic Properties in the System {Na}_{0.5} {CoO}_{3} Na 0.5 CoO 3

    Science.gov (United States)

    Estrada Rodriguez, C. A.; Pimentel, J. L.; Turatti, A. M.; Lopes, L. F.; Lopes, R. F.; Parra Vargas, C. A.

    2018-03-01

    The present study reports the structural, magnetic and electrical properties of the Na_{0.5}CoO3 system produced by the conventional solid state reaction method. The X-ray diffraction analysis allows to infer that the compound crystallizes in a monoclinic system with spatial group it{C2/m} and network parameters: a = 5.55 (8) Å, b = 4.87 (3) Å y c = 2.85 (8) Å. It is found that the mean grain size of the stoichiometric of system amounts approximately to 76 nm. Below 40 K, an antiferromagnetic behavior with {T}_{N }≈ 40 K was observed, while in the region between 80 and 190 K the system obeys the law of Curie-Weiss, and the effective magnetic moment was determined experimentally of 5.62{μ }B, indicating a high spin configuration for the Co^{2+ }ion ( S = 3/2) in the fundamental state 4T_{1g}. The system shows cluster spin glass properties with low temperatures, the temperature of magnetic moment freezing from ˜ 40 K. The behavior of the resistivity under absence of magnetic field and the presence of an insulating state between two different metallic states was observed. The metal-insulator transition occurred at two temperatures, the first around 170 K, and the second around 40 K, the latter in accordance with the magnetic transition temperature.

  17. Lead free Bi0.5Na0.5TiO3 (BNT) and polyvinylidene fluoride (PVDF) based nanocomposite for energy storage applications

    Science.gov (United States)

    Pradhan, Lagen Kumar; Pandey, Rabichandra; Kumar, Sunil; Kar, Manoranjan

    2018-05-01

    Novel ceramic-polymer nanocomposites have great potential for electrical energy storage applications due to its high energy storage density. In the present work, BNT and PVDF based flexible polymer nanocomposites (BNT-PVDF) with different volume fraction (ϕ = 0, 5, 10, 15) were fabricated by solution casting method. Enhancement in beta phase of PVDF polymer matrix with the volume fraction (ϕ = 5, 10, 15) of BNT has been confirmed by X-ray diffraction (XRD) technique as well as Fourier transform infrared (FTIR) spectroscopy analysis. The enhancement of β phase increases as compared to (α) phases with volume fraction (ϕ) of nanofiller (BNT) in the matrix (PVDF) due to internal stress at the interface as well as structural modification of PVDF matrix. BNT-PVDF nanocomposites (with ϕ=10) showed a high dielectric constant (ɛr ≈ 78) relative to pure PVDF (ɛr ≈ 10) at 100 Hz. In addition to this, it exhibits relaxor type ferroelectric behavior with energy storage efficiency up to 77% for the volume fraction (ϕ) of 10.

  18. NuSTAR observations of heavily obscured quasars at z ~ 0.5

    DEFF Research Database (Denmark)

    Lansbury, G. B.; Alexander, D. M.; Del Moro, A.

    2014-01-01

    We present NuSTAR hard X-ray observations of three Type 2 quasars at z ≈ 0.4-0.5, optically selected from the Sloan Digital Sky Survey. Although the quasars show evidence for being heavily obscured, Compton-thick systems on the basis of the 2-10 keV to [O III] luminosity ratio and multiwavelength...

  19. Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag/Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} current-perpendicular-to-plane pseudo spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J. W.; Sakuraba, Y., E-mail: Sakuraba.Yuya@nims.go.jp; Sasaki, T. T.; Hono, K. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Miura, Y. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Kyoto Institute of Technology, Electrical Engineering and Electronics, Kyoto 606-8585 (Japan)

    2016-03-07

    We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm{sup 2}) and 77% (31 mΩ μm{sup 2}) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

  20. A study on the polymer precursor formation and microstructure evolution of square-shaped (La{sub 0.5}Ba{sub 0.5})(Mn{sub 0.5}Fe{sub 0.5})O{sub 3} ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Romero, M.; Pardo, H.; Faccio, R.; Suescun, L.; Fernandez-Werner, L.; Mombru, A.W. [Univ. de la Republica, Montevideo (Uruguay). Cryssmat-Lab/Centro NanoMat; Univ. de la Republica, Montevideo (Uruguay). Centro Interdisciplinario de Nanotecnologia, Quimica y Fisica de Materiales; Vazquez, S.; Laborda, I. [Univ. de la Republica, Montevideo (Uruguay). Cryssmat-Lab/Centro NanoMat; Acosta, A. [Univ. de la Republica, Montevideo (Uruguay). Catedra de Quimica Inorganica; Castiglioni, J. [Univ. de la Republica, Montevideo (Uruguay). Catedra de Fisicoquimica

    2015-07-01

    The polymer precursor formation and the growth mechanism of (La{sub 0.5}Ba{sub 0.5})(Mn{sub 0.5}Fe{sub 0.5})O{sub 3} ceramic nanoparticles have been studied. First, we focused on the influence of isolated metals (La, Ba, Mn, Fe) on the polymer precursor formation by means of Raman, FT-IR, scanning electron microscopy and differential scanning calorimetry, showing that the presence of metal ions, especially iron, increases the oxidation rate of the polymer precursor, while the presence of barium leads to a higher degree of polymerization, preventing partial oxidation of the polymer at low temperatures and allowing the presence of nitrates at the combustion stage. Nevertheless, when all metals are present, the polymer precursor showed a largely homogeneous microstructure with a global average influence from all cations. Finally,we studied the microstructure evolution of nanoparticles obtained after calcination above 700 C. SAXS and TEM analysis suggests that the formation of square-shaped nanoparticles below 900 C and coalescence leads to the formation of larger-sized and round-shaped nanoparticles at 900 C.

  1. 77 FR 53892 - Determination That ALOXI (Palonosetron Hydrochloride) Capsules, 0.5 Milligram (Base), Were Not...

    Science.gov (United States)

    2012-09-04

    ... discontinued from marketing for reasons other than safety or effectiveness. ANDAs that refer to ALOXI... Sale for Reasons of Safety or Effectiveness AGENCY: Food and Drug Administration, HHS. ACTION: Notice...)) Capsules, 0.5 milligram (mg) (base), were not withdrawn from sale for reasons of safety or effectiveness...

  2. Clinically insubstantial cognitive side effects of bitemporal electroconvulsive therapy at 0.5 msec pulse width.

    Science.gov (United States)

    Warnell, Ronald L; Swartz, Conrad M; Thomson, Alice

    2011-11-01

    We measured cognitive side effects from bitemporal electroconvulsive therapy (ECT) using stimuli of 0.5 msec pulse width 900 milliamperes (mA). Mini-Mental State Exam (MMSE) and 21-item Hamilton Rating Scale for Depression (HRSD-21) were rated within 36 hours before and 36 hours after a series of 6 bitemporal ECT sessions on 15 patients age ≥45. MMSE remained high after ECT (pre-ECT mean 29, standard deviation [SD] 1.60, post-ECT mean 28.53, SD 1.36) with no significant change. The mean HRSD-21 fell from 27.5 to 16.3. Post-ECT MMSE was significantly and markedly higher than in previous studies of bitemporal ECT; all had used ECT stimuli of pulse width at least 1 msec. With stimuli of 0.5 msec pulse width and 900 mA, 6 bitemporal ECTs did not decrease MMSE score. This result leaves no opportunity for further decrease in basic cognitive side effects, and complements published reports of stronger physiological effects with stimuli of 0.5 msec pulse width and 900 mA. ECT stimuli of 0.5 msec pulse width and 900 mA are more desirable than wider pulse widths. Six bitemporal ECT sessions using these stimuli generally will not have more cognitive side effects than treatments with other placements, allowing maintenance of full efficacy with clinically insubstantial side effects.

  3. Transverse susceptibility as a probe of the magnetocrystalline anisotropy-driven phase transition in Pr0.5Sr0.5CoO3

    Science.gov (United States)

    Frey Huls, N. A.; Bingham, N. S.; Phan, M. H.; Srikanth, H.; Stauffer, D. D.; Leighton, C.

    2011-01-01

    Half-doped Pr1-xSrxCoO3 (x=0.5) displays anomalous magnetism, most notably manifest in the field-cooled magnetization versus temperature curves under different applied cooling fields. Recently, an explanation was advanced that a magnetocrystalline anisotropy transition driven by a structural transition at 120 K is the origin of this behavior. In this paper, we further elucidate the nature of the magnetic anisotropy across the low-temperature phase transition in this material by means of transverse susceptibility (TS) measurements performed using a self-resonant tunnel diode oscillator. TS probes magnetic materials by means of a small radio frequency oriented transverse to a dc field that sweeps from positive to negative saturation. TS scans as a function of field clearly reveal peaks associated with the anisotropy (HK) and switching fields (HS). When peak position is examined as a function of temperature, ˜120 K the signature of a ferromagnetic-to-ferromagnetic phase transition is evident as a sharp feature in HK and a corresponding cusp in HS. A third TS peak (not previously observed in other classes of magnetic oxides such as manganites and spinel ferrites) is found to be correlated with the crossover field (Hcr) in the unconventional magnetization versus temperature [M(T)] behavior. We observe a strong temperature dependence of Hcr at ˜120 K using this technique, which suggests the magnetic-field-influenced magnetocrystalline anisotropy transition. We show the switching between the high-field magnetization state and the low-field magnetization state associated with the magnetocrystalline anisotropy transition is irreversible when the magnetic field is recycled. Finally, we demonstrate that the TS peak magnitude indicates easy axis switching associated with this phase transition, even in these polycrystalline samples. Our results further confirm that TS provides new insights into the magnetic behavior of complex oxides.

  4. Oxygen vacancy as fatigue evidence of La0.5Sr0.5CoO3/PbZr0.4Ti0.6O3/La0.5Sr0.5CoO3 capacitors

    Science.gov (United States)

    Liu, B. T.; Chen, J. E.; Sun, J.; Wei, D. Y.; Chen, J. H.; Li, X. H.; Bian, F.; Zhou, Y.; Guo, J. X.; Zhao, Q. X.; Guan, L.; Wang, Y. L.; Guo, Q. L.; Ma, L. X.

    2010-09-01

    La0.5Sr0.5CoO3 (LSCO) films grown on SrTiO3 substrates, cooled at reduced oxygen pressures, ranging from 8×104 to 1×10-4 Pa, from the depostion temperature, are used as the bottom electrodes of PbZr0.4Ti0.6O3 (PZT) capacitors to study the impact of oxygen stoichiometry of the LSCO bottom electrodes on the structural and physical properties of LSCO/PZT/LSCO capacitors. It is found that the tetragonality, polarization and fatigue-resistance of PZT films decrease with the decrease of the cooling oxygen pressure. Almost 60% polarization degradation occurs for the PZT capacitor with the LSCO bottom electrode cooled in 1×10-4 Pa oxygen up to 1010 switching cycles, indicating that the oxygen vacancy of the bottom electrode can result in fatigue of the LSCO/PZT/LSCO capacitor.

  5. Ferrites Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} doped with samarium: structural analysis, morphological and electromagnetic; Ferritas Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} dopada com samario: analise estrutural, morfologica e eletromagnetica

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A.C.F.M.; Diniz, A.P., E-mail: anacristina@dema.ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academinca de Engenharia de Materiais; Viana, K.M.S. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, PE (Brazil). Escola de Ciencias e Tecnologia; Cornejo, D.R. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2010-07-01

    This paper proposes to investigate the sintering at 1200 deg C/2h of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Sm{sub x}O{sub 4} ferrite doped with 0.05; 0.075 e 0.1 mol of Sm synthesized by combustion reaction to evaluate the performance materials as absorbers of electromagnetic radiation. The influence of the concentration of samarium on the structure, morphology and electromagnetic properties of ferrites was studied. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic measurements and reflectivity measurements in the frequency range between 8-12 GHz. The results showed that increasing the concentration of samarium caused a decrease in particle size of the samples, encouraging, therefore, to obtain materials with better values of magnetization and reflectivity, allowing for use as absorbers in narrow-band frequency between 9-10 GHz. (author)

  6. Measles Antibody Titres In 0-5 Years Children At Aligarh

    Directory of Open Access Journals (Sweden)

    Kandpal S D

    1999-01-01

    Full Text Available Research Question: What is the level of measles antibodies in 0-5 year children? Objectives: 1.To assess the pattern of decline of maternal antibodies in 0-9 months infants. 2. To estimate the seropositivity for measles antibodies in vaccinated 9 months infants. Study design: Cross- sectional. Setting: Rural areas of District Aligarh, U.P. Participants: 456 children in the age group of 0-5 years. Statistical analysis: Percentages, correlation coefficient. Results: 1. In all the study subjects below 9 months of age, the transplacentally acquired maternal measles antibodies showed a linear decline with increase in age. Out of 202 study subjects who had been immunized against measles 195(96.50% were seropositive and 7(3.5% were seronegative for measles antibodies.

  7. New antiferromagnetic semiconductor CuCr1.5Sb0.5S4

    International Nuclear Information System (INIS)

    Kesler, Ya.A.; Koroleva, L.I.; Mikheev, M.G.; Odintsov, A.G.; Filimonov, D.S.

    1993-01-01

    New halcogenide compound with spinel-antiferromagnetic semiconductor CuCr 1.5 Sb 0.5 S 4 are obtained and studied for the first time. Magnetic properties of this compound, namely, magnetization linear dependence, maximum on PHI(T) curve in the low-temperature area and realization of the Curie-Weis law for paramagnetic susceptibility with negative paramagnetic temperature testiby to the fact that this compound is antiferromagnetic

  8. Secondary electron emission from 0.5--2.5-MeV protons and deuterons

    International Nuclear Information System (INIS)

    Thornton, T.A.; Anno, J.N.

    1977-01-01

    Measurement of the secondary electron currents leaving Al, V, Fe, 316 stainless steel, Nb, and Mo foils undergoing 0.5--2.5-MeV proton and deuteron bombardment were made to determine the secondary electron emission ratios for these ions. The measured secondary electron yields were of the order of 1.0, with the deuterons producing generally higher yields than the protons

  9. Gd2O3 doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 lead-free piezoelectric ceramics

    International Nuclear Information System (INIS)

    Fu, Peng; Xu, Zhijun; Chu, Ruiqing; Li, Wei; Wang, Wei; Liu, Yong

    2012-01-01

    Highlights: ► Gd 2 O 3 doped BNKT18 piezoelectric ceramics were designed and prepared. ► The electrical properties of the BNKT18 ceramics are improved with the addition of Gd 2 O 3 . ► The BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 has better electrical properties. -- Abstract: Gd 2 O 3 (0–0.8 wt.%)-doped 0.82Bi 0.5 Na 0.5 TiO 3 –0.18Bi 0.5 K 0.5 TiO 3 (BNKT18) lead-free piezoelectric ceramics were synthesized by a conventional solid-state process. The effects of Gd 2 O 3 on the microstructure, the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) data shows that Gd 2 O 3 in an amount of 0.2–0.8 wt.% can diffuse into the lattice of BNKT18 ceramics and form a pure perovskite phase. Scanning electron microscope (SEM) images indicate that the grain size of BNKT18 ceramics decreases with the increase of Gd 2 O 3 content; in addition, all the modified ceramics have a clear grain boundary and a uniformly distributed grain size. At room temperature, the ferroelectric and piezoelectric properties of the BNKT18 ceramics have been improved with the addition of Gd 2 O 3 , and the BNKT18 ceramics doped with 0.4 wt.% Gd 2 O 3 have the highest piezoelectric constant (d 33 = 137 pC/N), highest relative dielectric constant (ε r = 1023) and lower dissipation factor (tan δ = 0.044) at a frequency of 10 kHz. The BNKT18 ceramics doped with 0.2 wt.% Gd 2 O 3 have the highest planar coupling factor (k p = 0.2463).

  10. Use of 0.5% bupivacaine with buprenorphine in minor oral surgical procedures.

    Science.gov (United States)

    Nagpal, Varun; Kaur, Tejinder; Kapila, Sarika; Bhullar, Ramandeep Singh; Dhawan, Amit; Kaur, Yashmeet

    2017-01-01

    Minor oral surgical procedures are the most commonly performed procedures by oral and maxillofacial surgeons. Performance of painless surgical procedure is highly appreciated by the patients and is possible through the use of local anesthesia, conscious sedation or general anesthesia. Postoperative pain can also be controlled by the use of opioids, as opioid receptors exist in the peripheral nervous system and offers the possibility of providing postoperative analgesia in the surgical patient. The present study compares the efficacy of 0.5% bupivacaine versus 0.5% bupivacaine with 0.3 mg buprenorphine in minor oral surgical procedures. The present study was conducted in 50 patients who required minor oral surgical procedures under local anesthesia. Two types of local anesthetic solutions were used- 0.5% bupivacaine with 1:200000 epinephrine in group I and a mixture of 39 ml of 0.5% bupivacaine with epinephrine 1:200000 and 1 ml of 300 μg buprenorphine (3 μg/kg)in group II. Intraoperative and postoperative evaluation was carried out for both the anesthetic solutions. The mean duration of postoperative analgesia in bupivacaine group (508.92 ± 63.30 minutes) was quite less than the buprenorphine combination group (1840.84 ± 819.51 minutes). The mean dose of postoperative analgesic medication in bupivacaine group (1.64 ± 0.99 tablets) was higher than buprenorphine combination group (0.80 ± 1.08 tablets). There was no significant difference between the two groups regarding the onset of action of the anesthetic effect and duration of anesthesia. Buprenorphine can be used in combination with bupivacaine for patients undergoing minor oral surgical procedures to provide postoperative analgesia for a longer duration.

  11. Forbush decreases on November 6-12, 2004 observed by the Muon Detector Network

    Energy Technology Data Exchange (ETDEWEB)

    Savian, Jairo Francisco; Schuch, Nelson Jorge [Southern Regional Space Research Center, CRSPE/INPE-MCT, Santa Maria, RS (Brazil); Silva, Marlos Rockenbach da; Lago, Alisson dal; Echer, Ezequiel; Vieira, Luis Eduardo Antunes; Gonzalez, Walter Demetrio [National Institute for Space Research, INPE-MCT, Sao Jose dos Campos, SP (Brazil); Munakata, Kazuoki, E-mail: savian@lacesm.ufsm.br, E-mail: njschuch@lacesm.ufsm.br, E-mail: marlos@dge.inpe.br, E-mail: dallago@dge.inpe.br, E-mail: eecher@dge.inpe.br, E-mail: vieira-le@uol.com.br, E-mail: gonzalez@dge.inpe.br, E-mail: kmuna00@shinshu-u.ac.jp [Physics Department, Shinshu University, Matsumoto, (Japan)

    2007-07-01

    In this paper we study the relationship between interplanetary coronal mass ejections (ICMEs) and the muon count rate decreases detected of the muon detector network on November 6-12, 2004. The muon detector network is composed by the detectors installed at Nagoya (Japan), Hobart (Australia) and the prototype detector installed at the 'Observatorio Espacial do Sul - OES/CRSPE/INPE-MCT', located in Sao Martinho da Serra, RS, Brazil. With the muon count rate observed by the muon detector network, we will be able to observe, in the future, the direction in which a given ICME moves, and with that, we will be able to calculate their angle of incidence on the Earth. Also, with this muon network, we will be able to send alerts of up to 12 hours before the arrival of a shock or an ICME. The space weather forecast method using cosmic rays will be a very important tool because it provides a forecast with good antecedence. (author)

  12. Three-Dimensional Zn0.5Cd0.5S/Reduced Graphene Oxide Hybrid Aerogel: Facile Synthesis and the Visible-Light-Driven Photocatalytic Property for Reduction of Cr(VI in Water

    Directory of Open Access Journals (Sweden)

    Wei Xiao

    2016-01-01

    Full Text Available A series of three-dimensional ZnxCd1-xS/reduced graphene oxide (ZnxCd1-xS/RGO hybrid aerogels was successfully synthesized based on a one-pot hydrothermal approach, which were subsequently used as visible-light-driven photocatalysts for photoreduction of Cr(VI in water. Over 95% of Cr(VI was photoreduced by Zn0.5Cd0.5S/RGO aerogel material within 140 min, and such photocatalytic performance was superior to that of other ZnxCd1-xS/RGO aerogel materials (x≠0.5 and bare Zn0.5Cd0.5S. It was assumed that the enhanced photocatalytic activity of Zn0.5Cd0.5S/RGO aerogel was attributed to its high specific surface area and the preferable synergetic catalytic effect between Zn0.5Cd0.5S and RGO. Besides, Zn0.5Cd0.5S/RGO aerogel materials were robust and durable enough so that they could be reused several times with merely limited loss of photocatalytic activity. The chemical composition, phase, structure, and morphology of Zn0.5Cd0.5S/RGO aerogel material were carefully examined by a number of techniques like XRD, SEM, TEM, BET, Raman characterizations, and so on. It was found that Zn0.5Cd0.5S/RGO aerogel possessed hierarchically porous architecture with the specific surface area as high as 260.8 m2 g−1. The Zn0.5Cd0.5S component incorporated in Zn0.5Cd0.5S/RGO aerogel existed in the form of solid solution nanoparticles, which were uniformly distributed in the RGO matrix.

  13. 0.5% Liposome-encapsulated 5-aminolevulinic acid (ALA) photodynamic therapy for acne treatment.

    Science.gov (United States)

    An, Jee-Soo; Kim, Jeong-Eun; Lee, Dong-Hun; Kim, Byung-Yoon; Cho, Soyun; Kwon, In-Ho; Choi, Won-Woo; Kang, Seong-Min; Won, Chong-Hyun; Chang, Sung-Eun; Lee, Mi-Woo; Choi, Jee-Ho; Moon, Kee-Chan

    2011-02-01

    Photodynamic therapy using topical 5-aminolevulinic acid (ALA) has been successful in treating acne vulgaris, but sun avoidance for at least 48 hours after treatment is necessary due to the risk of post-treatment photosensitivity. Recently, a lower concentration of liposome-encapsulated 5-ALA was introduced to minimize this risk. To evaluate the efficacy and safety of liposome-encapsulated 0.5% 5-ALA in the photodynamic therapy of inflammatory acne and its effects on sebum secretion in Asian skin. Thirteen Korean subjects with inflammatory acne were administered 0.5% ALA spray before photoradiation treatment. Photoradiation was performed at 3.5-6.0 J/cm(2) three times during each of two visits, performed 2 weeks apart. Improvement of acne was evaluated subjectively and objectively based on the Korean Acne Grading System. Sebum secretion was measured quantitatively at each visit. The mean reduction in acne grade at the end of the treatment was 43.2%. Of the patients, 69.2% reported improvements in subjective skin oiliness, but fewer showed objective reductions in sebum secretion as determined by the Sebumeter® SM10. No serious adverse events were observed. Photodynamic therapy using liposome-encapsulated 0.5% 5-ALA improved inflammatory acne with minimal side effects in Asians.

  14. Microstructure and mechanical properties of TiC0.5 reinforced copper matrix composites

    International Nuclear Information System (INIS)

    Li, Mengqi; Zhai, Hongxiang; Huang, Zhenying; Liu, Xiaohan; Zhou, Yang; Li, Shibo; Li, Cuiwei

    2013-01-01

    Cu–Al alloy matrix composites containing in-situ TiC 0.5 particles were fabricated by sintering of a mixture of Cu and Ti 2 AlC powders at 1150 °C for 60 min in Ar atmosphere. The micron-sized Ti 2 AlC particles were decomposed into submicron TiC 0.5 grains during the sintering process, meanwhile, Al atoms entered into Cu to form Cu–Al alloy matrix. It was shown that the Cu–Al alloy matrix also consisted of ultrafine grains. Compression tests indicate TiC 0.5 particles can improve mechanical properties significantly, and the ductility maintains at a comparatively high level. The fracture strength of 40Ti 2 AlC/Cu sample reaches 1126 MPa with 12.8% fracture strain. The 20Ti 2 AlC/Cu and 30Ti 2 AlC/Cu samples keep undamaged even after the strain of 26.7%

  15. Microstructure and mechanical properties of TiC{sub 0.5} reinforced copper matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mengqi; Zhai, Hongxiang, E-mail: hxzhai@sina.com; Huang, Zhenying; Liu, Xiaohan; Zhou, Yang; Li, Shibo; Li, Cuiwei

    2013-12-20

    Cu–Al alloy matrix composites containing in-situ TiC{sub 0.5} particles were fabricated by sintering of a mixture of Cu and Ti{sub 2}AlC powders at 1150 °C for 60 min in Ar atmosphere. The micron-sized Ti{sub 2}AlC particles were decomposed into submicron TiC{sub 0.5} grains during the sintering process, meanwhile, Al atoms entered into Cu to form Cu–Al alloy matrix. It was shown that the Cu–Al alloy matrix also consisted of ultrafine grains. Compression tests indicate TiC{sub 0.5} particles can improve mechanical properties significantly, and the ductility maintains at a comparatively high level. The fracture strength of 40Ti{sub 2}AlC/Cu sample reaches 1126 MPa with 12.8% fracture strain. The 20Ti{sub 2}AlC/Cu and 30Ti{sub 2}AlC/Cu samples keep undamaged even after the strain of 26.7%.

  16. Physical Models of Layered Polar Firn Brightness Temperatures from 0.5 to 2 GHz

    Science.gov (United States)

    Tan, Shurun; Aksoy, Mustafa; Brogioni, Marco; Macelloni, Giovanni; Durand, Michael; Jezek, Kenneth C.; Wang, Tian-Lin; Tsang, Leung; Johnson, Joel T.; Drinkwater, Mark R.; hide

    2015-01-01

    We investigate physical effects influencing 0.5-2 GHz brightness temperatures of layered polar firn to support the Ultra Wide Band Software Defined Radiometer (UWBRAD) experiment to be conducted in Greenland and in Antarctica. We find that because ice particle grain sizes are very small compared to the 0.5-2 GHz wavelengths, volume scattering effects are small. Variations in firn density over cm- to m-length scales, however, cause significant effects. Both incoherent and coherent models are used to examine these effects. Incoherent models include a 'cloud model' that neglects any reflections internal to the ice sheet, and the DMRT-ML and MEMLS radiative transfer codes that are publicly available. The coherent model is based on the layered medium implementation of the fluctuation dissipation theorem for thermal microwave radiation from a medium having a nonuniform temperature. Density profiles are modeled using a stochastic approach, and model predictions are averaged over a large number of realizations to take into account an averaging over the radiometer footprint. Density profiles are described by combining a smooth average density profile with a spatially correlated random process to model density fluctuations. It is shown that coherent model results after ensemble averaging depend on the correlation lengths of the vertical density fluctuations. If the correlation length is moderate or long compared with the wavelength (approximately 0.6x longer or greater for Gaussian correlation function without regard for layer thinning due to compaction), coherent and incoherent model results are similar (within approximately 1 K). However, when the correlation length is short compared to the wavelength, coherent model results are significantly different from the incoherent model by several tens of kelvins. For a 10-cm correlation length, the differences are significant between 0.5 and 1.1 GHz, and less for 1.1-2 GHz. Model results are shown to be able to match the v

  17. The microstructure of Mg–4Zn–2Al–0.5Ca aged alloy

    International Nuclear Information System (INIS)

    Lin Xiaoping; Dong Yun; Ye Jie; Song Boyang

    2012-01-01

    Highlights: ► The microstructure of Mg–4Zn–2Al–0.5Ca aged alloy was investigated by TEM. ► Edge dislocations, ordered zones and moiré fringes are found in alloy. ► Ca can improve the thermal stability of precipitates. - Abstract: In this study, we investigated the microstructure of a new Mg–4Zn–2Al–0.5Ca aged alloy with TEM and HRTEM. The age hardening process of Mg–4Zn–2Al–0.5Ca alloy aged at 120 °C or 160 °C follows a similar pattern: a period of fluctuation of hardness present before the alloy reaches its maximum hardness. The atomic arrangement is different in different areas of the microstructure possibly due to the difference of the segregated degree of the solute atoms in the alloy. The microstructure of alloy aged at 120 °C for 230 h consists of cellular textures, ordered zone, elongated precipitates and disc-like precipitates, while the microstructure of the alloy aged at 160 °C for 32 h consists of edge dislocations, ordered zones and moiré fringe. No MgZn precipitates are found in the peak aged microstructures of alloys aged at 120 °C and 160 °C. It is reasonable to believe that Ca is a particularly effective trace addition in improving the thermal stability of precipitation in Mg–4Zn–2Al alloy aged at 120 °C and 160 °C.

  18. Microstructure and electrical properties of (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} lead-free ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ting [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Chen, Xiao-ming, E-mail: xmchen@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Qiu, Yan-zi [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710119 (China); Lian, Han-li [School of Science, Xi’an University of Posts and Telecommunications, Xi’an, 710121 (China); Chen, Wei-ting [Department of Electrical Engineering, National Cheng Kung University, Tainan City, 701, Taiwan (China)

    2017-01-15

    The (1−x)[0.8Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.2Bi{sub 0.5}K{sub 0.5}TiO{sub 3}]-xBiCoO{sub 3} (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO{sub 3} perovskite structure. The doping of BiCoO{sub 3} causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO{sub 3}-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO{sub 3} amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO{sub 3}. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO{sub 3}. • The doping causes a decrease in lattice parameters and an increase in grain size. • T{sub d} of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

  19. Rotamak discharges in a 0.5 m diameter, spherical device

    International Nuclear Information System (INIS)

    Euripides, P.; Jones, I.R.; Deng Chuanbao

    1997-01-01

    In the rotamak concept, a rotating magnetic field is used to drive toroidal plasma current in a compact torus device in a non-inductive manner. The latest results from a 0.5 m diameter rotamak apparatus are presented. These show that, for a given filling pressure of hydrogen, it is possible to drive more current, whilst simultaneously preserving the compact torus configuration, by increasing the amount of RF power transferred to the plasma. Attention is drawn to the fact that a fair evaluation of the rotamak concept requires experimentation at higher RF power levels than are presently available. (author). Letter-to-the-editor

  20. Microstructure and electrical properties of (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 lead-free ceramics

    International Nuclear Information System (INIS)

    Wang, Ting; Chen, Xiao-ming; Qiu, Yan-zi; Lian, Han-li; Chen, Wei-ting

    2017-01-01

    The (1−x)[0.8Bi_0_._5Na_0_._5TiO_3-0.2Bi_0_._5K_0_._5TiO_3]-xBiCoO_3 (x = 0, 0.02, 0.05, abbreviated as BNKT, BNKT-002Co, BNKT-005Co, respectively) lead-free ferroelectric ceramics were prepared via the solid state reaction method. The phase structure, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties of the ceramics were investigated comparatively by using a combination of characterization techniques. All the samples exhibit typical X-ray diffraction peaks of ABO_3 perovskite structure. The doping of BiCoO_3 causes a decrease in lattice parameters and an increase in grain size of the ceramics. The Raman spectroscopy results suggest a lattice distortion due to the doping. It is found that BNKT-002Co and BNKT-005Co have higher depolarization temperatures compared with BNKT. The Curie-Weiss law and modified Curie-Weiss law explored a diffuse phase transition character for all the samples. The results of ultraviolet–visible diffuse reflectance suggests that BiCoO_3-doped ceramics possess higher defect concentration. The impedance analysis shows a temperature dependent relaxation behavior, and the activation energy for the electrical responses varies with the change of BiCoO_3 amount. The ferroelectric and piezoelectric properties of the ceramics decrease due to the doping of BiCoO_3. Based on the results of the Rayleigh analysis, it was suggested that the differences in the electrical properties among the ceramics are closely related to the change in oxygen vacancy concentration. - Highlights: • BNKT-xCo ceramics were prepared by solid-state reaction method. • Electrical properties of BNKT ceramics are changed by the doping of BiCoO_3. • The doping causes a decrease in lattice parameters and an increase in grain size. • T_d of the ceramics increases with increasing x. • Oxygen vacancies play key role in determining electrical properties of the ceramics.

  1. Highlighting micrographic structures of uranium alloys containing 0.5 to 10 per cent wt molybdenum

    International Nuclear Information System (INIS)

    Laniesse, J.; Bouleau, M.

    1959-02-01

    The authors report a study which aimed at determining for different uranium molybdenum alloys and with respect to their molybdenum content a polishing method which allows a relatively simple grain examination in the as-cast condition, an as perfect as possible resolution of eutectic decompositions, and the appropriate conditions to highlight structures (beta-alpha and gamma-alpha martensite transformations, beta phase retention and decomposition, transient structures, eutectoid decomposition, and so on). Alloys differ by their molybdenum content: from 0.5 to 1 per cent wt, 1.5 to 3 per cent wt, 5 to 10 per cent wt

  2. Meaningful, Authentic and Place-Based Informal Science Education for 6-12 Students

    Science.gov (United States)

    Ito, E.; Dalbotten, D. M.

    2014-12-01

    American Indians are underrepresented in STEM and especially in Earth sciences. They have the lowest high school graduation rate and highest unemployment. On the other hand, tribes are in search of qualified young people to work in geo- and hydro-technical fields to manage reservations' natural resources. Dalbotten and her collaborators at the Fond du Lac Band of Lake Superior Chippewa and local 6-12 teachers ran a place-based but non-themed informal monthly science camps (gidakiimanaaniwigamig) for 7 years starting 2003. Camps were held on reservation and some activities focused on observing seasonal changes. The students enjoyed coming to the camps but the camp activities went largely unnoticed by the reservation itself. For the last 5 years, we and the same cast of characters from the gidakiimanaaniwigamig camps ran a very place-based, research-based camp program, manoomin. The research was focused on manoomin (wild rice) which is a culturally important plant and food that grows in local lakes and wetlands. Manmade changes in hydrology, toxic metals from mining, and changing weather patterns due to climate change threaten this precious resource. Our plan was for 6-12 students to investigate the past, the present and the future conditions of manoomin on and around the reservation. It became clear by 3rd year that the research project, as conceived, was overly ambitious and could not be completed at the level we hoped in a camp setting (6 weekend camps = 6 full days per year). However, students felt that they were involved in research that was beneficial to their reservation, reported gaining self-confidence to pursue a career in science, and stated a desired to obtain a college degree. They also became aware of STEM employment opportunities on reservation that they could aim for. The camps also fostered a trusting relationship between researchers at Fond du Lac resource managers and the U. of MN. Based on these experiences, we proposed a new format for these

  3. Thermal Behaviour of Sm0.5 R 0.5FeO3 (R = Pr, Nd) Probed by High-Resolution X-ray Synchrotron Powder Diffraction.

    Science.gov (United States)

    Pavlovska, Olena; Vasylechko, Leonid; Buryy, Oleh

    2016-12-01

    Mixed ferrites Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 with orthorhombic perovskite structure isotypic with GdFeO3 were synthesized by solid-state reaction technique in air at 1473 K. Structural parameters obtained at room temperature prove a formation of continuous solid solutions in the SmFeO3-PrFeO3 and SmFeO3-NdFeO3 pseudo-binary systems. Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 show strongly anisotropic nonlinear thermal expansion: thermal expansion in the b direction is twice lower than in the a and c directions. The average linear thermal expansion coefficients of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 in the temperature range of 298-1173 K are in the limits of (9.0-11.1) × 10(-6) K(-1), which is close to the values reported for the parent RFeO3 compounds. Subtle anomalies in the lattice expansion of Sm0.5Pr0.5FeO3 and Sm0.5Nd0.5FeO3 detected at 650-750 K reflect magnetoelastic coupling at the magnetic ordering temperature T N.

  4. Uranium-molybdenum alloys containing 0,5 to 3 per cent by weight of molybdenum

    International Nuclear Information System (INIS)

    Lehmann, J.

    1959-01-01

    The following properties have been determined in the new cast state of uranium alloys containing 0.5-1-1.8-2 and 3.5 per cent of molybdenum: micro-graphical aspect, crystalline structure, thermal expansion, the mechanical characteristics, behaviour when subjected to cyclic temperature variations, and heat treatment. The transformation curves have been established for continuous cooling at rates varying between 2.5 and 200 deg. C per minute, using a dilatation method for the alloys containing 1.0, 2.0 and 3.0 per cent Mo. T.T.T. curves have been traced for 0.5 and 1.0 per cent Mo alloys and the Ms points determined for alloys containing 2.0 and 3.0 par cent Mo. In this way it has been possible to show the different results of transformation, brought about either by nucleation and diffusion or by shear - the alloy containing 1 per cent Mo, give two martensites α' and α'' and the alloys containing 2 and 3 per cent Mo give one martensite with a band structure. (author) [fr

  5. The effect of 0.5% ropivacaine on epidural blood flow

    DEFF Research Database (Denmark)

    Dahl, J B; Simonsen, L; Mogensen, T

    1990-01-01

    Twenty patients scheduled for elective abdominal surgery received epidural analgesia with 20 ml 0.5% ropivacaine or 0.5% bupivacaine. Epidural blood flow was measured by an epidural 133Xe clearance technique on the day before surgery (no local anaesthetic) and again 1 h before surgery, 30 min after...... injection of the local anaesthetic during continuous infusion (8 ml/h). Median initial blood flow was 5.0 ml/min and 6.0 ml/min per 100 g tissue in patients receiving ropivacaine and bupivacaine, respectively. After epidural bupivacaine, blood flow increased in 8 of 10 patients to 6.9 ml/min per 100 g...... tissue (P less than 0.05) in contrast to a decrease in 9 of 10 patients to 3.3 ml/min per 100 g tissue after ropivacaine (P less than 0.05), (P less than 0.01 between groups). The median level of sensory analgesia was T3.5 and T4.5 in the ropivacaine and bupivacaine group, respectively (P greater than 0...

  6. Microstructural and magnetic study of ferrites Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} sintered by microwave energy; Estudo microestrutral e magnetico de ferritas Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} sinterizadas por energia de micro-ondas

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, V.C.S.; Costa, A.C.F.M., E-mail: veronicacristhina@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Programa de Pos-Graduacao em Ciencias e Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais; Cornejo, D.R. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica

    2014-07-01

    The study of the processing of Ni-Zn ferrite is of extreme importance to improve its magnetic properties, as they are directly influenced by the final microstructure of the material. This study evaluated the influence of exposure time in the sintering of Ni-Zn ferrite phase by microwave energy, and its subsequent microstructural characterization, and magnetic. The samples of Ni-Zn ferrite were sintered using microwave energy at a temperature of 1200 °C and an exposure time of 10, 20 and 30 minutes, respectively. Then were characterized by X-ray diffraction spectroscopy, scanning electron microscopy and magnetic measurements. With the results, it was observed that all samples obtained from the formation Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} phase with all high intensity peaks. It was possible to obtain a nanostructure with maximum saturation magnetization of 71 emu / g for the sample sintered in longer exposure time. (author)

  7. Microdosimetry of 0.5 to 2.0 MeV electron beams

    International Nuclear Information System (INIS)

    Braby, L.A.; Roesch, W.C.

    1980-08-01

    The energy imparted in microscopic volumes by electron beams with initial energies from 0.5 to 2.0 MeV has been measured at various depths in plastic. The problems associated with measuring energy deposition spectra of low LET radiations are serious, but the potential importance of these measurements in radiation biophysics justifies the effort required to obtain them. Recent results obtained by Goodhead et al. indicate an RBE greater than 2 for 0.3 keV x-rays compared to 250 kV x-rays, and our results with Chlamydomonas reinhardi indicate an RBE of 1.6 for a 1.5 MeV electron beam at a depth of 400 gm/cm 2 in lucite compared to the same beam at the surface. Development of a theory which appears to explain these results in terms of the microscopic distribution of energy deposition has motivated a detailed study of energy deposition spectra for an electron beam attenuated by various thicknesses of lucite. Simulated sites from 0.5 to 1.9 μm in diameter were studied. The values of anti y determined in these single event measurements compare favorably with those calculated from direct measurements of z reported previously. As expected, the means of the distributions increase significantly with increasing depth in an absorber

  8. Simulated cosmic microwave background maps at 0.5 deg resolution: Unresolved features

    Science.gov (United States)

    Kogut, A.; Hinshaw, G.; Bennett, C. L.

    1995-01-01

    High-contrast peaks in the cosmic microwave background (CMB) anisotropy can appear as unresolved sources to observers. We fit simluated CMB maps generated with a cold dark matter model to a set of unresolved features at instrumental resolution 0.5 deg-1.5 deg to derive the integral number density per steradian n (greater than absolute value of T) of features brighter than threshold temperature absolute value of T and compare the results to recent experiments. A typical medium-scale experiment observing 0.001 sr at 0.5 deg resolution would expect to observe one feature brighter than 85 micro-K after convolution with the beam profile, with less than 5% probability to observe a source brighter than 150 micro-K. Increasing the power-law index of primordial density perturbations n from 1 to 1.5 raises these temperature limits absolute value of T by a factor of 2. The MSAM features are in agreement with standard cold dark matter models and are not necessarily evidence for processes beyond the standard model.

  9. Anticipating and addressing workplace static magnetic field effects at levels <0.5 mT.

    Science.gov (United States)

    Emery, R J; Hopkins, J R; Charlton, M A

    2000-11-01

    Magnetic resonance, once a research tool limited to the basic sciences, has experienced an increase in popularity due to its unique ability to analyze certain living systems in vivo. Expanding applications in the biomedical sciences have resulted in magnetic sources being located in research institutions nationally. Space and resource limitations sometimes necessitate siting magnetic resonance units in proximity to other institutional operations. For magnetic field shielding and personnel protection considerations, the generally accepted 0.5 mT (milliTesla) limit for implanted cardiac devices is commonly used as the conservative basis for decisions. But the effects of magnetic fields on equipment can be easily observed at levels far below 0.5 mT, often resulting in concern and apprehension on the part of personnel in the surrounding areas. Responding to recurrent worker concerns spawned by noticeable effects on equipment at exposure levels information, practicing radiation safety professionals can better anticipate facility incompatibility issues and improve their responses to worker concerns initiated by observed effects on equipment.

  10. Exposure to phthalates in house dust and associated allergies in children aged 6-12years.

    Science.gov (United States)

    Ait Bamai, Yu; Araki, Atsuko; Kawai, Toshio; Tsuboi, Tazuru; Saito, Ikue; Yoshioka, Eiji; Cong, Shi; Kishi, Reiko

    2016-11-01

    Phthalates are widely used as plasticizers in household products. Several studies have reported an association between phthalate exposure and an increased risk of allergies. The present study estimated phthalate exposure in children aged 6-12years and assessed potential correlations with allergies. House dust samples were collected from floors and multi-surface objects >35cm above the floor. Urine samples were collected from the first morning void of the day. Daily phthalate intake (DI dust and DI) was estimated using both house dust and urinary metabolite concentrations. Exposure to di-2-ethylhexyl phthalate (DEHP) in floor dust was associated with parental-reported rhino-conjunctivitis. After stratification by gender, this trend was found to only occur in boys. Furthermore, urinary mono-isobutyl phthalate was inversely associated with parental-reported wheeze in boys. DI dust of benzyl butyl phthalate (BBzP) and DEHP were significantly correlated with DI_BBzP and DI_DEHP, respectively. These correlations were stronger with floor than with multi-surface dust. Our results suggest that, among Japanese children, house dust from low surfaces, such as living room floors, might play a meaningful role in the indoor environmental exposure pathway for BBzP and DEHP. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. An Experimental Trial of Adaptive Programming in Drug Court: Outcomes at 6, 12 and 18 Months.

    Science.gov (United States)

    Marlowe, Douglas B; Festinger, David S; Dugosh, Karen L; Benasutti, Kathleen M; Fox, Gloria; Harron, Ashley

    2014-06-01

    Test whether an adaptive program improves outcomes in drug court by adjusting the schedule of court hearings and clinical case-management sessions pursuant to a priori performance criteria. Consenting participants in a misdemeanor drug court were randomly assigned to the adaptive program (n = 62) or to a baseline-matching condition (n = 63) in which they attended court hearings based on the results of a criminal risk assessment. Outcome measures were re-arrest rates at 18 months post-entry to the drug court and urine drug test results and structured interview results at 6 and 12 months post-entry. Although previously published analyses revealed significantly fewer positive drug tests for participants in the adaptive condition during the first 18 weeks of drug court, current analyses indicate the effects converged during the ensuing year. Between-group differences in new arrest rates, urine drug test results and self-reported psychosocial problems were small and non-statistically significant at 6, 12 and 18 months post-entry. A non-significant trend (p = .10) suggests there may have been a small residual impact (Cramer's ν = .15) on new misdemeanor arrests after 18 months. Adaptive programming shows promise for enhancing short-term outcomes in drug courts; however, additional efforts are needed to extend the effects beyond the first 4 to 6 months of enrollment.

  12. New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

    Science.gov (United States)

    Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

    2013-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED

  13. Magnetoelectric effect of (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Rahaman, Md. D., E-mail: dalilurrahaman1976@gmail.com [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Saha, S.K.; Ahmed, T.N. [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Saha, D.K. [Materials Science Division, Atomic Energy Centre, PO Box 164, Dhaka 1000 (Bangladesh); Hossain, A.K.M. Akther [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)

    2014-12-15

    The magnetoelectric composites with chemical compositions (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σ{sub AC}) vs. log(ω{sup 2}) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm{sup −1} Oe{sup −1} is obtained for x=20 wt% at room temperature. - Highlights: • XRD patterns confirmed the coexistence of ferroelectric and ferrimagnetic phases. • Dielectric dispersion observed at low frequencies due to interfacial polarization. • Linearity in logσ{sub ac} vs. logω{sup 2} is due to small polaron hopping mechanism. • Maximum ME voltage coefficient 600 μV cm{sup −1} Oe{sup −1} observed for 20% of ferrite.

  14. Orthogonal 4,10 and 6,12 substitution of dibenzo[def,mno]chrysene polycyclic aromatic small molecules

    KAUST Repository

    Koldemir, Unsal

    2017-07-14

    A series of new polycyclic aromatic hydrocarbon compounds based on (4,10-disubstituted-dibenzo[def,mno]chrysene-6,12-dione) and 4,10 di-substituted 6,12-bis(triisopropylsilylethynyl)dibenzo[def,mno]chrysene are reported with tunable electronic properties through varied molecular architecture. Starting with an inexpensive commercially available textile dye known as Vat Orange #3, (4,10-dibromo-dibenzo[def,mno] chrysene-6,12-dione) we extended the conjugation at the 4- and 10-positions by the attachment of both electron rich and deficient hexylvinylphthalimide, thiophene, hexylthiophene, triphenylamine, and hexylbithiophene aromatic groups, and studied the resultant optoelectronic properties. By applying various synthetic metal-catalyzed reactions, soluble dibenzo[def,mno]chrysene and dibenzo[def,mno]chrysene-6,12-dione derivatives were achieved with optical edge band gaps between 2.30 eV and 1.65 eV.

  15. Orthogonal 4,10 and 6,12 substitution of dibenzo[def,mno]chrysene polycyclic aromatic small molecules

    KAUST Repository

    Koldemir, Unsal; Tinkham, Jonathan S.; Johnson, Robert; Lim, Bogyu; Yemam, Henok A.; Gagnon, Kevin J.; Parkin, Sean; Sellinger, Alan

    2017-01-01

    A series of new polycyclic aromatic hydrocarbon compounds based on (4,10-disubstituted-dibenzo[def,mno]chrysene-6,12-dione) and 4,10 di-substituted 6,12-bis(triisopropylsilylethynyl)dibenzo[def,mno]chrysene are reported with tunable electronic properties through varied molecular architecture. Starting with an inexpensive commercially available textile dye known as Vat Orange #3, (4,10-dibromo-dibenzo[def,mno] chrysene-6,12-dione) we extended the conjugation at the 4- and 10-positions by the attachment of both electron rich and deficient hexylvinylphthalimide, thiophene, hexylthiophene, triphenylamine, and hexylbithiophene aromatic groups, and studied the resultant optoelectronic properties. By applying various synthetic metal-catalyzed reactions, soluble dibenzo[def,mno]chrysene and dibenzo[def,mno]chrysene-6,12-dione derivatives were achieved with optical edge band gaps between 2.30 eV and 1.65 eV.

  16. Creep of ex-service 0.5CrMoV steel at low strain rates

    Czech Academy of Sciences Publication Activity Database

    Kloc, Luboš

    510-511, - (2009), s. 70-73 ISSN 0921-5093. [Creep 2008. Bayreuth, 04.05.2008-09.05.2008] R&D Projects: GA MŠk 1P05OC006 Institutional research plan: CEZ:AV0Z20410507 Keywords : Residual creep life * Low strain creep * Low alloy steel Subject RIV: JG - Metallurgy Impact factor: 1.901, year: 2009

  17. Adjustable Grazing Incidence X-ray Optics with 0.5 Arc Second Resolution

    Science.gov (United States)

    Reid, Paul

    We seek to develop adjustable grazing incidence optics for x-ray astronomy. The goal of this development is thin, lightweight mirrors with angular resolution of 0.5 arc seconds, comparable to the Chandra X-ray Observatory. The new mirror design consists of thin segments of a Wolter-I grazing incidence mirror, with piezo-electric material deposited directly on the back surface of the mirror. Depositing a pattern of independently addressable electrodes on top of the piezoelectric material produces an array of independent piezo cells. Energizing a particular cell introduces a localized deformation in the mirror without the need for a reaction structure. By applying the appropriate voltage to the piezo cells, it is possible to correct mirror figure errors that result from mirror fabrication, gravity release, mounting, and thermal effects. Because the thin mirrors segments are lightweight, they can be densely nested to produce collecting area thirty times that of Chandra, on an affordably priced mission. This Supporting Technology program is a follow-on to an existing APRA program. In the existing program we demonstrated the first successful deposition of piezoelectric material on thermally formed glass substrates. We showed that the localized deformations produced by the piezo cells match finite element predictions, and the piezo cell adjustment range meets requirements necessary to achieve the desired figure correction. We have also shown through simulation that representative mirror figure errors can be corrected via modeled influence functions to achieve 0.5 arc sec imaging performance. This provides a firm foundation on which to develop further the technology. We will continue to optimize the deposition of thin piezoelectric films onto thermally formed glass and electroplated metal mirror segments to improve yield and manufacturability. We will deposit piezoelectric material onto conical mirror segments and demonstrate figure correction in agreement with prediction

  18. Electrochemical behaviour of copper in N,N-dimethylformamide + 0.5 M potassium perchlorate solution

    Directory of Open Access Journals (Sweden)

    S. MENTUS

    2000-09-01

    Full Text Available The electrochemical deposition and dissolution of copper in 0.0025 M CuSO4 + N,N-dimethylformamide + 0.5 M KClO4 solution was examined by the rotating disc and potentiodynamic methods. Both platinum and copper were used as working electrodes. A wide polarization range –1 to +2 V vs. SCE, and several temperatures between 25 and 55°C were encompased. The Cu/electrolyte interface was found to be permanently out of equilibrium, as a consequence of the development of a passivating layer. In accordance with the classic theory of a copper electrode in acidified aqueous solutions, the cathodic and anodic Tafel lines of metallic copper define a unique value of the exchange current density, however, their slopes do not correspond to the classic theory.

  19. Results of Zea mays seeds β- irradiation in 0 - 5 Gy range

    International Nuclear Information System (INIS)

    Chicea, Dan; Racuciu, Mihaela

    2008-01-01

    In this study young plants, obtained from the control and beta irradiated seeds, were studied in laboratory experiments. Zea mays seeds with uniform genophond were irradiated with 90 Sr source in the 0 - 5 Gy range. Increased germination percentage was observed under the influence of different radiation doses. We found that small doses of β- radiation have a stimulating effect on the growth of the plantlets, the maximum simulation (among the doses we used) being induced by 0.615 Gy and is statistically significant. We investigated the chlorophyll a to b ratio and the average length variations with the irradiation dose and present the results. Key words: b- radiation, Zea mays, germination rate, plants growth, photoassimilatory pigments,

  20. Characterization of aluminum x-pinch plasmas driven by the 0.5 TW Lion accelerator

    International Nuclear Information System (INIS)

    Qi, N.; Hammer, D.A.; Kalantantar, D.H.; Noonan, W.A.; Rondeau, G.; Workman, J.B.; Richardson, M.C.

    1989-01-01

    The x-pinch, obtained by crossing two fine wires at one or more points as the load for the 0.5 TW Lion accelerator, has been used as a bright x-ray source. High density and temperature hot spots are observed at the crossing point(s). From these hot spots, an intense, spatially confined burst of x-rays is emitted which can serve as a pump for resonant photo-pumping lasers. The authors present experimental results concerning the radiation emission using Al x-pinches. The optimum mass loading for different ionization stages of Al ions and the total x-ray energy yields are examined. The density and temperature of the plasma and the size of the hot spots are measures. Based upon the results of these experiments, the authors evaluate resonant photopumping schemes such as those involving Be-like ions, using the Al x-pinch emission as the pump source

  1. Simulated cosmic microwave background maps at 0.5 deg resolution: Basic results

    Science.gov (United States)

    Hinshaw, G.; Bennett, C. L.; Kogut, A.

    1995-01-01

    We have simulated full-sky maps of the cosmic microwave background (CMB) anisotropy expected from cold dark matter (CDM) models at 0.5 deg and 1.0 deg angular resolution. Statistical properties of the maps are presented as a function of sky coverage, angular resolution, and instrument noise, and the implications of these results for observability of the Doppler peak are discussed. The rms fluctuations in a map are not a particularly robust probe of the existence of a Doppler peak; however, a full correlation analysis can provide reasonable sensitivity. We find that sensitivity to the Doppler peak depends primarily on the fraction of sky covered, and only secondarily on the angular resolution and noise level. Color plates of the simulated maps are presented to illustrate the anisotropies.

  2. A Case Report of Severe Corneal Toxicity following 0.5% Topical Moxifloxacin Use

    Directory of Open Access Journals (Sweden)

    A.P. Vignesh

    2015-02-01

    Full Text Available Moxifloxacin is a widely used topical antibiotic in various bacterial infections of the eye. Its safety and efficacy have been proved by many studies. We report a case of a rare adverse effect following its use. A 10-year-old female who had presented with acute bacterial conjunctivitis in both eyes with no corneal involvement was started on preservative-free 0.5% topical moxifloxacin four times a day. The child developed a severe form of corneal toxicity in both eyes with circumcorneal congestion and corneal edema following its use. The child's visual acuity had dropped from 20/20 to 20/400 in both the eyes. Topical moxifloxacin was discontinued, following which the cornea cleared dramatically and the visual acuity became normal. This case indicates that though rare, topical moxifloxacin can cause severe keratitis and that more studies need to be conducted to evaluate its safety.

  3. Investigation of Cutting Quality of Remote DOE Laser Cutting in 0.5 mm Stainless Steel

    Science.gov (United States)

    Villumsen, Sigurd Lazic; Kristiansen, Morten

    It has previously been shown that the stability of the remote fusion cutting (RFC) process can be increased by modifying the intensity profile of the laser by means of a diffractive optical element (DOE). This paper investigates the quality of remote DOE cutting (RDC) conducted with a 3 kW single mode fiber laser in 0.5 mm stainless steel. An automatic measurement system is used to investigate how the travel speed, focus offset and angle of incidence effect the kerf width and kerf variance. The study shows that the RDC process has a very low kerf width variance, and that the kerf width decreases with cutting speed. Furthermore, selected etched samples show a significant increase in the perpendicularity of the cuts when compared to RFC. Also, on average, the depth of the layer of molten material for RFC is 83% deeper than for RDC.

  4. Adsorption of methane on Zn(bdc)(ted)0.5 microporous metal-organic framework

    Science.gov (United States)

    Krungleviciute, Vaiva; Pramanik, Sanhita; Migone, Aldo; Li, Jing

    2011-03-01

    Zn(bdc)(ted)0.5 is metal-organic framework crystallized in a tetragonal space group with a 3D porous structure containing intersecting channels of two different sizes. The larger channels are parallel to the c axis and have a cross section 7.5 × 7.5 AA. The smaller channels are along both the a- and b-axes and have a cross section of 4.8 × 3.2 AA. We measured methane adsorption isotherms at several different temperatures between 82 and 102 K. We calculated the effective specific surface area, isosteric heat and binding energy values. Two distinct substeps were observed in the isotherms corresponding to two different adsorption sites. The origin of the substeps will be discussed.

  5. Hydrogen behaviour in PWR containment evaluated with MAAP4.0.5

    International Nuclear Information System (INIS)

    Bilic-Zabric, T.; Basic, I.; Spiler, J.

    2004-01-01

    The possible impacts of the non-uniform hydrogen distribution and the consequent fast burning should be assessed in the light of newer research information on hydrogen management. The review should include the hydrogen source term, both for the in-vessel and ex-vessel period, and investigate the potential effects on the hydrogen management strategy. NPP Krsko will repeat MAAP 4.0.5 calculation for the most important Rx vessel failure sequences taken from Individual Plant Examination Project (with molten core-concrete interaction (MCCI) and with no MCCI) including wet cavity strategy. Mass and energy gases releases of analyzed sequences will be used to assess the non-uniform hydrogen distribution and the consequent fast burning by GOTHIC 7.1 (3-D).(author)

  6. Graphite moderator annealing of the experimental reactor for irradiation (0.5 MW)

    International Nuclear Information System (INIS)

    Oliveira Avila, Carlos Alberto de; Pires, Luis Fernando Goncalves

    1995-01-01

    This work describes an operational procedure for the annealing of the graphite moderator in the 0,5 MW Experimental Reactor for Irradiation. A theoretical methodology has been developed for calculating the temperature field during the annealing process. The equations for mass, momentum, and energy conservation for the coolant as well as for the energy conservation in the moderator are solved numerically. The energy stored in the graphite and released in the annealing is accounted for by the use of a modified source term in the energy conservation equation for the moderator. A good agreement has been found for comparisons of the calculations with annealing data from the BEPO reactor. The major parameters affecting annealing have also been determined. (author). 8 refs, 11 figs

  7. [Musculoskeletal biopsies in an open 0.5-T-MR system].

    Science.gov (United States)

    Pretzsch, M; Scholz, R; Moche, M; Thomas, M; Tannapfel, A; von Salis-Soglio, G

    2005-01-01

    MR-guided interventions have been successful in different medical disciplines. The aim of this paper is to report our results with the application of MR-guided biopsies of musculoskeletal lesions using an open 0.5-T-MR scanner and further to discuss these results on the basis of the available literature. Between 1998 and 2003 30 patients (average age 44.1 years) underwent a total of 31 biopsies. The interventions were performed in an open 0.5-T MRI system using an active optical localization system as well as a navigation system. For the motion tracking we used T (1)-weighted real-time sequences with 0.25 pictures per second. For the sampling MR-compatible instruments were used that were specially developed for this purpose. The data of this retrospective investigation are based on the evaluation of the patient documents and the radiological findings. On the basis of the histological findings the technical success rate and the histological overall accuracy were determined. In 81 % of the biopsies the histological diagnosis was correct. In cases of suspected inflammation the histological accuracy was smaller (70 %). No differences were observed between skeletal and soft-tissue lesions. The technical success rate amounted to 77.5 %. No procedural or anesthesiological complications occurred. The mean operating time amounted to 65 min including the time for motion tracking. In cases of suspected lesions of the musculoskeletal system, the MR-guided biopsy represents a promising and safe procedure to get a histological diagnosis. In cases of sufficient size of the lesion sampling of a representative probe is possible. On account of the outstanding performance in soft-part contrasting, the sensitive structures surrounding the lesion can be saved. Substantial disadvantages of the procedure are the high costs for personal and material and the long operating time.

  8. Assessment of magnetic resonance imaging of the breast using 0.5 T equipment

    International Nuclear Information System (INIS)

    Vilanova, J. C.; Barcelo, J.; Ferrer, J.; Castaner, F.; Miro, J.; Bassaganyas, R.; Viejo, N.; Albanell, J.; Villalon, M.

    2002-01-01

    To evaluate the efficacy of a magnetic resonance imaging technique of the breast using half-field equipment (0.5 T). We evaluated 191 magnetic resonance (MRI) studies made at our center from March 1998 to March 2001 using Signa Contour 0.5 T MRI equipment of General Electric. A dedicated bilateral breast made at fat saturation in the coronal plane before administering intravenous gadolinium, then 6 consecutive times after contrast administration. The sequence acquisition time was 70-90 seconds Image post processing included subtraction and analysis of the intensity/time curves in the region of interest (ROI) together with morphological evaluation of the lesion. Additional T2 weighted fast-spin-echo sequences (FSE T2), T1-weighted spin-echo (SE T1), FSE T2 with fat suppression, and STIR with water saturation were made for studies of breast implants. The clinical indications for MRI study of the breast were masses (n=79), microcalcifications (n=7), asymmetry (n=17), cases of indeterminate risk (n=7), postoperative control (n=51), and breast implants (n=25). The histological diagnosis was benign in 31 lesions and malignant in 73 lesions. The sensitivity specificity, and reliability of breast MRI were 93%, 81% and 89% respectively. Multicenter/multifocal neoplasms were found in 8% of patients and bilateral neoplasms in 2%. The therapeutic attitude was modified in 18% of the patients with breast cancer as a result of MRI findings. The results confirm the usefulness of MRI in the management of patients with breast cancer. Likewise, the present study demonstrated that breast MRI can be carried out with half-field equipment with the same reliability as with full-field equipment as long as specific breast cots are used rapid 3D sequences, and image processing with suitable software. (Author) 28 refs

  9. NuSTAR observations of heavily obscured quasars at z ∼ 0.5

    Energy Technology Data Exchange (ETDEWEB)

    Lansbury, G. B.; Alexander, D. M.; Moro, A. Del; Gandhi, P.; Aird, J. [Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Assef, R. J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States); Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Baloković, M.; Grefenstette, B. W.; Harrison, F. A. [Cahill Center for Astrophysics, 1216 East California Boulevard, California Institute of Technology, Pasadena, CA 91125 (United States); Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Catlica de Chile, Casilla 306, Santiago 22 (Chile); Boggs, S. E. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Christensen, F. E.; Craig, W. W. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hailey, C. J. [Columbia Astrophysics Laboratory, 550 W 120th Street, Columbia University, NY 10027 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Koss, M., E-mail: g.b.lansbury@durham.ac.uk [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); and others

    2014-04-10

    We present NuSTAR hard X-ray observations of three Type 2 quasars at z ≈ 0.4-0.5, optically selected from the Sloan Digital Sky Survey. Although the quasars show evidence for being heavily obscured, Compton-thick systems on the basis of the 2-10 keV to [O III] luminosity ratio and multiwavelength diagnostics, their X-ray absorbing column densities (N {sub H}) are poorly known. In this analysis, (1) we study X-ray emission at >10 keV, where X-rays from the central black hole are relatively unabsorbed, in order to better constrain N {sub H}. (2) We further characterize the physical properties of the sources through broad-band near-UV to mid-IR spectral energy distribution analyses. One of the quasars is detected with NuSTAR at >8 keV with a no-source probability of <0.1%, and its X-ray band ratio suggests near Compton-thick absorption with N {sub H} ≳ 5 × 10{sup 23} cm{sup –2}. The other two quasars are undetected, and have low X-ray to mid-IR luminosity ratios in both the low-energy (2-10 keV) and high-energy (10-40 keV) X-ray regimes that are consistent with extreme, Compton-thick absorption (N {sub H} ≳ 10{sup 24} cm{sup –2}). We find that for quasars at z ∼ 0.5, NuSTAR provides a significant improvement compared to lower energy (<10 keV) Chandra and XMM-Newton observations alone, as higher column densities can now be directly constrained.

  10. Post-marketing surveillance of levofloxacin 0.5% ophthalmic solution for external ocular infections.

    Science.gov (United States)

    Kanda, Yoshiko; Kayama, Tomoko; Okamoto, Shinji; Hashimoto, Masako; Ishida, Chiemi; Yanai, Tomoko; Fukumoto, Mitsuru; Kunihiro, Eiichi

    2012-12-01

    Levofloxacin 0.5% ophthalmic solution is an antibacterial formulation, which was approved and marketed for the treatment of ocular infections in Japan in 2000. This study was designed to investigate the safety and efficacy of levofloxacin 0.5% ophthalmic solution in patients who received treatment for external ocular bacterial infections in regular clinical practice. Patients were recruited from more than 800 medical facilities in Japan, in accordance with Japanese Ministry of Health, Labour and Welfare ordinance guidelines. They were followed during three distinct time periods: April 2000 to December 2001, January 2002 to June 2003, and July 2003 to December 2004. Information from 6760 patients receiving levofloxacin for the treatment of a variety of ocular infections was collected. Levofloxacin was well tolerated: adverse drug reactions (ADRs) were reported in 42 of 6686 patients (0.63%), with no serious ADRs reported. The most commonly reported ADRs were ocular disorders such as blepharitis, eye irritation, and punctate keratitis. The incidence of ADRs did not differ significantly with age, but it was significantly higher in females (0.82%) than in males (0.36%; p = 0.028). A clinical response was observed in 95.5% of patients receiving levofloxacin, with no difference in response between the three time periods. The rate of response to levofloxacin by bacterial disease ranged from 97.4% in keratitis to 88.3% in dacryocystitis. The rate was lower in patients with dacryocystitis, elderly patients, patients with a long duration of illness, and relapsing cases (all p marketing surveillance of levofloxacin, conducted over 4 years, confirms the safety and efficacy of levofloxacin in regular clinical use and highlights that levofloxacin is a promising treatment for a variety of external ocular bacterial infections.

  11. A 0.5 Tesla Transverse-Field Alternating Magnetic Field Demagnetizer

    Science.gov (United States)

    Schillinger, W. E.; Morris, E. R.; Finn, D. R.; Coe, R. S.

    2015-12-01

    We have built an alternating field demagnetizer that can routinely achieve a maximum field of 0.5 Tesla. It uses an amorphous magnetic core with an air-cooled coil. We have started with a 0.5 T design, which satisfies most of our immediate needs, but we can certainly achieve higher fields. In our design, the magnetic field is transverse to the bore and uniform to 1% over a standard (25 mm) paleomagnetic sample. It is powered by a 1 kW power amplifier and is compatible with our existing sample handler for automated demagnetization and measurement (Morris et al., 2009). It's much higher peak field has enabled us to completely demagnetize many of the samples that previously we could not with commercial equipment. This capability is especially needed for high-coercivity sedimentary and igneous rocks that contain magnetic minerals that alter during thermal demagnetization. It will also enable detailed automated demagnetization of high coercivity phases in extraterrestrial samples, such as native iron, iron-alloy and sulfide minerals that are common in lunar rocks and meteorites. Furthermore, it has opened the door for us to use the rock-magnetic technique of component analysis, using coercivity distributions derived from very detailed AF demagnetization of NRM and remanence produced in the laboratory to characterize the magnetic mineralogy of sedimentary rocks. In addition to the many benefits this instrument has brought to our own research, a much broader potential impact is to replace the transverse coils in automated AF demagnetization systems, which typically are limited to peak fields around 0.1 T.

  12. Effect of timolol 0.5% gel and solution on pulmonary function in older glaucoma patients.

    Science.gov (United States)

    Stewart, W C; Day, D G; Holmes, K T; Stewart, J A

    2001-06-01

    To evaluate the effect of timolol maleate solution or gel forming solution versus placebo on pulmonary function in patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease. After a screening visit, each patient was randomized by a Latin square technique to receive placebo twice daily, 0.5% timolol solution twice daily, or 0.5% timolol gel once a day (placebo given as second dose) to each eye for 2 weeks. Subjects then were crossed over to the two other treatments for 2-week treatment intervals. At each visit, patients were received a dose 15 minutes before pulmonary function testing. This study began with 25 patients, and 20 finished the trial. There was no difference between treatment groups for the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio (P > 0.1). The mean FEV1 for timolol solution, timolol gel, and placebo was 2.42 L, 2.45 L, and 2.50 L, respectively. The mean FVC for timolol solution, timolol gel, and placebo was 3.33 L, 3.38 L, and 3.44 L, respectively. No difference in intraocular pressure was observed between the timolol solution (17.1 +/- 3.3 mm Hg) and timolol gel (17.1 +/- 3.6 mm Hg) between the treatment periods (P > 0.1). No difference in side effects was observed between treatment groups (P > 0.05). In older patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease, nonselective beta-blockers should not worsen pulmonary function.

  13. Haemodynamic preservation in cesarean sections by low dose 0.5% hyperbaric bupivacaine

    International Nuclear Information System (INIS)

    Ahmad, M.; Ahmad, M.

    2017-01-01

    Spinal anaesthesia is technique of choice for caesarean sections and hyperbaric bupivacaine is a recommended drug for this popular block. Although safe but few complications are haemodynamic changes, postdural puncture headache, cauda equina syndrome and radiculopathy. However, hypotension remains the common side effect which is believed to occur in 95% of patients resulting in reduction of uteroplacental perfusion causing foetal acid-base abnormalities. Various doses regimes are in safe anaesthesia practice for providing regional anaesthesia for such patients with least detrimental effects on foetal outcome. This study was carried out to find the effective dose of 0.5% hyperbaric bupivacaine in caesarean section patients by comparing two different doses. Methods: After enrolling two hundred patients of C section (Caesarean section) for this study, 90 patients were selected to compare the effects of 0.5% hyperbaric bupivacaine. Group A (n=45) received 10 mg of drug while group B (n=45) received 12 mg for spinal anaesthesia. Onset of block, sensory and motor level, haemodynamic changes, surgery time, maternal satisfaction, APGAR score and incidence of complications were compared in two groups. Results: Blood pressure decreases were less in Group A (p-0.074) but not statistically significant. Phenylephrine for hypotension was given to 17% vs 5% in group B. Maternal satisfaction was found to be better in group B 33 vs 17 but was statistically significant (p 0.034). 2% patients had bradycardia in group A which was treated by atropine. No complications were reported in either group. Conclusion: Doses of hyperbaric bupivacaine for spinal anaesthesia in caesarean sections must be at least 12 mg because it produces excellent anaesthesia and maternal satisfaction without complications. (author)

  14. Epidural 0.5% levobupivacaine with dexmedetomidine versus fentanyl for vaginal hysterectomy: A prospective study

    Directory of Open Access Journals (Sweden)

    Kumkum Gupta

    2014-01-01

    Full Text Available Background: Epidural adjuvants enhance the quality and duration of surgical anesthesia. The present study was aimed to compare the hemodynamic, sedative, and analgesia potentiating effects of dexmedetomidine versus fentanyl with epidural 0.5% levobupivacaine for vaginal hysterectomy. Patients and Methods: Sixty consented females of ASA physical status I and II aged 35-65 years weighing 55-75 kg, were double blindly randomized into two treatment groups. Patients received epidural 0.5% levobupivacaine 15 ml either with of 25 μg dexmedetomidine (Group LD or 50 μg fentanyl (Group LF and the total volume of study solution was kept 16 ml. Onset of analgesia at T10, sensory and motor block levels and duration of analgesia were observed. Intra-operatively, they were assessed for sedation, hemodynamic changes, respiratory efficiency, and side effects. The data obtained, was compiled systematically and analyzed statistically using Chi-square test and ANOVA. Value of P < 0.05 is considered significant. Result: The demographic profile was comparable between groups. The onset of sensory analgesia at T10 (7.25 ± 2.3 versus 9.27 ± 2.79 min and time to achieve complete motor blockade (19.27 ± 4.7 versus 22.78 ± 5.57 min was significantly earlier in patients of LD Group. The intraoperative hemodynamic changes were comparable between groups. Ramsey Sedation score was better in LD group with statistically significance. Postoperative analgesia was significantly prolonged in LD Group. Incidence of nausea, vomiting, and pruritus was high in LF group. Conclusion: Dexmedetomidine was better than fentanyl as an epidural adjuvant for providing early onset of sensory analgesia, adequate sedation with no respiratory depression and prolonged postoperative analgesia.

  15. 78 FR 27971 - Determination That REV-EYES (Dapiprazole Hydrochloride Ophthalmic Solution), 0.5%, Was Not...

    Science.gov (United States)

    2013-05-13

    ...] Determination That REV-EYES (Dapiprazole Hydrochloride Ophthalmic Solution), 0.5%, Was Not Withdrawn From Sale... ophthalmic solution), 0.5%, was not withdrawn from sale for reasons of safety or effectiveness. This... ophthalmic solution, 0.5%, if all other legal and regulatory requirements are met. FOR FURTHER INFORMATION...

  16. Whole-grain food consumption in Singaporean children aged 6-12 years.

    Science.gov (United States)

    Neo, Jia En; Binte Mohamed Salleh, Saihah; Toh, Yun Xuan; How, Kesslyn Yan Ling; Tee, Mervin; Mann, Kay; Hopkins, Sinead; Thielecke, Frank; Seal, Chris J; Brownlee, Iain A

    2016-01-01

    Public health bodies in many countries are attempting to increase population-wide habitual consumption of whole grains. Limited data on dietary habits exist in Singaporean children. The present study therefore aimed to assess whole grain consumption patterns in Singaporean children and compare these with dietary intake, physical activity and health parameters. Dietary intake (assessed by duplicate, multipass, 24-h food recalls), physical activity (by questionnaire) and anthropometric measurements were collected from a cross-section of 561 Singaporean children aged 6-12 years. Intake of whole grains was evaluated using estimates of portion size and international food composition data. Only 38·3 % of participants reported consuming whole grains during the dietary data collection days. Median intake of whole grains in consumers was 15·3 (interquartile range 5·4-34·8) g/d. The most commonly consumed whole-grain food groups were rice (29·5 %), wholemeal bread (28·9 %) and ready-to-eat breakfast cereals (18·8 %). A significantly lower proportion of Malay children (seven out of fifty-eight; P < 0·0001) consumed whole grains than children of other ethnicities. Only 6 % of all children consumed the amount of whole grains most commonly associated with improved health outcomes (48 g/d). There was no relationship between whole grain consumption patterns and BMI, waist circumference or physical activity but higher whole grain intake was associated with increased fruit, vegetable and dairy product consumption (P < 0·001). These findings demonstrate that consumption of whole grain foods is low at a population level and infrequent in Singaporean children. Future drives to increase whole-grain food consumption in this population are likely to require input from multiple stakeholders.

  17. Improved Si0.5Ge0.5/Si interface quality achieved by the process of low energy hydrogen plasma cleaning and investigation of interface quality with positron annihilation spectroscopy

    Science.gov (United States)

    Liao, M.-H.; Chen, C.-H.

    2013-04-01

    The Positron Annihilation Spectra (PAS), Raman, and Photoluminescence spectroscopy reveal that Si0.5Ge0.5/Si interface quality can be significantly improved by the low energy plasma cleaning process using hydrogen. In the PAS, the particularly small value of lifetime and intensity near the Si0.5Ge0.5/Si interface in the sample with the treatment indicate that the defect concentration is successfully reduced 2.25 times, respectively. Fewer defects existed in the Si0.5Ge0.5/Si interface result in the high compressive strain about 0.36% in the top epi-Si0.5Ge0.5 layer, which can be observed in Raman spectra and stronger radiative recombination rate about 1.39 times for the infrared emission, which can be observed in the photoluminescence spectra. With better Si0.5Ge0.5/Si interface quality, the SiGe-based devices can have better optical and electrical characteristics for more applications in the industry. The PAS is also demonstrated that it is the useful methodology tool to quantify the defect information in the SiGe-based material.

  18. Synthesis of nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of ammonia into water-in-oil microemulsion in a rotor–stator reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingwen; Wang, Hongrun; Arowo, Moses; Sun, Baochang, E-mail: sunbc@mail.buct.edu.cn; Chen, Jianfeng; Shao, Lei, E-mail: shaol@mail.buct.edu.cn [Beijing University of Chemical Technology, State Key Laboratory of Organic–Inorganic Composites (China)

    2015-01-15

    A gas-microemulsion reaction precipitation method was employed to prepare nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of NH{sub 3} into water-in-oil (W/O) microemulsion in a rotor–stator reactor . The effects of different operating conditions including final pH of the microemulsion, reaction temperature, initial Ce{sup 3+} and Zr{sup 4+} concentration, rotation speed, and gas–liquid volumetric ratio were investigated. Nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} with an average diameter of about 5.5 nm, a specific surface area of 215.6 m{sup 2}/g and a size distribution of 4–8 nm was obtained under the optimum operating conditions. The as-prepared nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} was loaded with Au to prepare nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst which was subsequently used for CO oxidation test. CO conversion rate reached 100 % at room temperature, indicating high catalytic activity of the nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst.

  19. Room-temperature ferromagnetism in Fe-based perovskite solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials

    Science.gov (United States)

    Hung, Nguyen The; Bac, Luong Huu; Trung, Nguyen Ngoc; Hoang, Nguyen The; Van Vinh, Pham; Dung, Dang Duc

    2018-04-01

    The integration of ferromagnetism in lead-free ferroelectric materials is important to fabricate smart materials for electronic devices. In this work, (1 - x)Bi0.5Na0.5TiO3 + xMgFeO3-δ materials (x = 0-9 mol%) were prepared through sol-gel method. X-ray diffraction characterization indicated that MgFeO3-δ materials existed as a well solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials. The rhombohedral structure of Bi0.5Na0.5TiO3 materials was distorted due to the random distribution of Mg and Fe cations into the host lattice. The reduced optical band gap and the induced room-temperature ferromagnetism were due to the spin splitting of transition metal substitution at the B-site of perovskite Bi0.5Na0.5TiO3 and the modification by A-site co-substitution. This work elucidates the role of secondary phase as solid solution in Bi0.5Na0.5TiO3 material for development of lead-free multiferroelectric materials.

  20. Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Daisuke; Yang, Chen; Lin, Liwei [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Heidari, Amir [Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States); Najar, Hadi [Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States); Horsley, David A. [Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States); Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States)

    2016-02-01

    We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O{sub 2} in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000) was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.

  1. Evolution of galaxies in clusters. V. A study of populations since zapprox.0.5

    International Nuclear Information System (INIS)

    Butcher, H.; Oemler, A. Jr.

    1984-01-01

    In this paper we analyze photometry of 33 clusters of galaxies, with redshifts between 0.003 (the Virgo Cluster) and 0.54 (Cl 0016+16) to search for evolution of the colors of cluster populations. In each cluster we select these galaxies brighter than M/sub V/ = -20 which are within the circular area containing the inner 30% of the total Jupiter population. From the distribution of these galaxies in the color-magnitude plane, we determine the fraction of galaxies whose rest-frame B-V colors are at least 0.2 mag bluer than the ridge line of the early type galaxies at that magnitude. We define this to be the blue galaxy population, f/sub B/, and find it to have the following characteristics in compact, concentrated clusters: (1) For z or approx. =0.1 f/sub B/ increases with redshift reaching f/sub B/approx.0.25 at z = 0.5. (3) The values of f/sub B/ seen in clusters at a particular redshift are mostly consistent with clusters being random samples of one homogeneous galaxy population, but there is some evidence that processes within individual clusters may also affect the galaxy content

  2. Femoral head epiphysis growth and development among Chinese children aged 0-5 years.

    Science.gov (United States)

    Luo, Jiayou; Tang, Jin; Zhou, Libo; Zeng, Rong; Mou, Jinsong; Zhang, Lingli

    2009-05-01

    The aim of this study was to examine the pattern of femoral head epiphysis growth and development among Chinese children. Between January and December, 2007, we randomly sampled 1,450 healthy Chinese children (0-5 years old) from Hunan Provincial Children's Hospital in Changsha, Hunan, China. The diameter of femoral head epiphysis was measured by pelvic X-ray photography and processed by medical image processing software. The growth of femoral head epiphysis in girls was 2-3 months earlier than that in boys. The diameter of femoral head epiphysis increased with advancing age in both girls and boys, but the diameter of femoral head epiphysis in 2, 3, 4, 6, and 10-month-old girls was significantly larger than that in boys. Cubic regression equations between the diameter of femoral head epiphysis and age were created for boys and girls that could be used to predict the diameter of femoral head epiphysis. In conclusion, there was gender difference in femoral head epiphysis growth and development among Chinese children, and our prediction models will provide the guidance for early diagnosis of diseases related to the growth and development of the femoral head epiphysis.

  3. CLIC, a 0.5 to 5 TeV e$^{\\pm}$ Compact Linear Collider

    CERN Document Server

    Delahaye, J P; Braun, Hans Heinrich; Carron, G; Chautard, F; Coosemans, Williame; Corsini, R; D'Amico, T E; Dehler, M; Godot, J C; Guignard, Gilbert; Hagel, J; Hutchins, S; Johnson, C D; Jensen, E; Kamber, I; Millich, Antonio; Pearce, P; Potier, J P; Riche, A J; Rinolfi, Louis; Schulte, Daniel; Suberlucq, Guy; Thorndahl, L; Valentini, M; Warner, D J; Wilson, Ian H; Wuensch, Walter; Napoly, O; Raubenheimer, T O; Ruth, Ronald D

    1998-01-01

    The CLIC study of a high energy (0.5 - 5 TeV), high luminosity (10^34 - 10^35 cm^-2 sec^-1) e± linear collider is presented. Beam acceleration using high frequency (30 GHz) normal-conducting structure s operating at high accelerating fields (100 to 200 MV/m) significantly reduces the length and, in consequence the cost of the linac. Based on new beam and linac parameters derived from a recently dev eloped set of general scaling laws for linear colliders, the beam stability is shown to be similar to lower frequency designs in spite of the strong wake-field dependency on frequency. A new cost effe ctive and very efficient drive beam generation scheme for RF power production by the so-called "Two Beam Acceleration (TBA)" method is described. It uses a conventional thermionic gun and a fully-load ed normal-conducting linac operating at low frequency (937 MHz) to generate and accelerate the drive beam bunches and RF multiplication by funneling in compressor rings to produce the desired bunch st ructure. Recent 30...

  4. Precise optical observation of 0.5-GPa shock waves in condensed materials

    Science.gov (United States)

    Nagayama, Kunihito; Mori, Yasuhito

    1999-06-01

    Precision optical observation method was developed to study impact-generated high-pressure shock waves in condensed materials. The present method makes it possible to sensitively detect the shock waves of the relatively low shock stress around 0.5 GPa. The principle of the present method is based on the use of total internal reflection by triangular prisms placed on the free surface of a target assembly. When a plane shock wave arrives at the free surface, the light reflected from the prisms extinguishes instantaneously. The reason is that the total internal reflection changes to the reflection depending on micron roughness of the free surface after the shock arrival. The shock arrival at the bottom face of the prisms can be detected here by two kinds of methods, i.e., a photographic method and a gauge method. The photographic method is an inclined prism method of using a high-speed streak camera. The shock velocity and the shock tilt angle can be estimated accurately from an obtained streak photograph. While in the gauge method, an in-material PVDF stress gauge is combined with an optical prism-pin. The PVDF gauge records electrically the stress profile behind the shockwave front, and the Hugoniot data can be precisely measured by combining the prism pin with the PVDF gauge.

  5. Comparison of MR sequences in early cerebral infarction at 0.5 T

    International Nuclear Information System (INIS)

    Saatci, I.; Baskan, O.; Cekirge, H.S.; Besim, A.

    2000-01-01

    To compare the diagnostic values of fluid-attenuated inversion recovery (FLAIR) and gradient spin-echo (GRASE) with those of conventional spin-echo (SE) and fast SE T2-weighted sequences in the evaluation of acute cerebrovascular lesions at 0.5 T. Material and Methods: Twenty-two consecutive patients with the clinical diagnosis of acute cerebrovascular accident were examined by MR imaging within the first 48 h of ictus. MR examination included 5-mm axial conventional SE and turbo SE (TSE) T2-weighted, dual-echo GRASE and FLAIR sequences. The patients also had pre- and postcontrast T1-weighted axial images. Two examiners evaluated the images and scored the conspicuity of the acute lesions. Results: Regardless of location, FLAIR provided the best lesion conspicuity in the detection of acute infarcts, followed by the GRASE sequence. In the posterior fossa, TSE and SE demonstrated the lesions better than GRASE and FLAIR techniques. In the detection of hemorrhagic elements within the ischemic region, TSE demonstrated statistically significant superiority over other sequences. Conclusion: In the detection of acute ischemic lesions in locations other than the posterior fossa, FLAIR provided the best lesion conspicuity among four T2-weighted sequences, including SE, TSE, GRASE and FLAIR. However, for the posterior fossa examination, preference of SE or TSE T2-weighted sequences is suggested

  6. Desarrollo y optimización de una jalea de piroxicam 0,5 %

    Directory of Open Access Journals (Sweden)

    Oscar García Pulpeiro

    Full Text Available Se desarrolló por primera vez en Cuba, una formulación de jalea de piroxicam al 0,5 %. Se tomó como referencia la composición de la formulación líder del mercado FELDENE GELâ, a la cual se le efectuaron algunas modificaciones. Se realizaron 4 experimentos en las evaluaciones preliminares que sirvieron de base para la etapa posterior de diseño y optimización de la formulación. Se aplicó un diseño de experimentos con mezcla, para lo cual se emplearon como variables independientes la concentración de Carbopol 940, trietanolamina y hidroxipropilmetilcelulosa. Se evaluó la influencia de estos componentes en el pH, el área de extensibilidad y en algunas propiedades organolépticas. A partir de estos resultados, se seleccionó una formulación óptima.

  7. Effect of Giardia infection on growth and psychomotor development of children aged 0-5 years.

    Science.gov (United States)

    Simsek, Z; Zeyrek, F Yildiz; Kurcer, M A

    2004-04-01

    Giardiasis, an intestinal protozoan infection caused by Giardia intestinalis, is common in southeastern Anatolia, Turkey. In this cross-sectional survey, to investigate the role of giardiasis on growth and psychomotor development, we studied 160 children aged 0-5 years. Data were collected using a structured questionnaire, anthropometry, Ankara Developmental Screening Inventory, and laboratory analysis of fecal samples. The results showed that 50 per cent of the subjects were infected with at least one pathogen of intestinal parasitic infections. Giardia intestinalis was the most frequent pathogenic parasite. Giardia-infected children had a risk for stunted (OR = 7.67, 95 per cent CI = 2.25-26.16; p = 0.001) and poor psychomotor development (OR = 2.68, 95 per cent CI = 1.09-6.58; p = 0.030). The data indicate that Giardia intestinalis infection has an adverse impact on child linear growth and psychomotor development. In the primary healthcare centers, during the programme of the monitoring growth and developmental status of children, following children in terms of Giardia, diagnosis and treatment will have a positive effect on child health.

  8. Power and reactive power simultaneous control by 0.5 MJ superconducting magnet energy storage

    International Nuclear Information System (INIS)

    Ise, Toshifumi; Tsuji, Kiichiro; Murakami, Yoshishige

    1984-01-01

    Superconducting magnet energy storage (SMES) is expected to be widely applied to the pulsed sources for fusion reactor research and to the energy storage substituting for pumping-up power stations, because of its fast energy storing and discharging and very high efficiency. Some results have been obtained so far. In this paper, however, the simultaneous control of power and reactive power is considered for an energy storage composed of two sets of thyristorized power conversion system and superconducting magnets in series connection, and a direct digital control system is described on the principle, design and configuration including the compensator, and on the experiment using the 0.5 MJ superconducting magnet energy storage installed in the Superconduction Engineering Experiment Center, Osaka University. The results obtained are as follows: (1) P control priority mode and Q control priority mode (in which power and reactive power control has priority, respectively) were proposed as the countermeasures when the simultaneous control of power and reactive power became impossible; (2) the design method was established, by which power and reactive power control loops can independently be designed as a result of simulation; (3) the achievement of the simultaneous control of power and reactive power was confirmed by using P-control priority mode and Q-control priority mode, in the experiment using the control system designed by simulation. The validity of simulation model was also confirmed by actual response waveforms. (Wakatsuki, Y.)

  9. Comparison of MR sequences in early cerebral infarction at 0.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Saatci, I.; Baskan, O.; Cekirge, H.S.; Besim, A. [Hacettepe Univ. Hospital, Ankara (Turkey). Radiology Dept.

    2000-11-01

    To compare the diagnostic values of fluid-attenuated inversion recovery (FLAIR) and gradient spin-echo (GRASE) with those of conventional spin-echo (SE) and fast SE T2-weighted sequences in the evaluation of acute cerebrovascular lesions at 0.5 T. Material and Methods: Twenty-two consecutive patients with the clinical diagnosis of acute cerebrovascular accident were examined by MR imaging within the first 48 h of ictus. MR examination included 5-mm axial conventional SE and turbo SE (TSE) T2-weighted, dual-echo GRASE and FLAIR sequences. The patients also had pre- and postcontrast T1-weighted axial images. Two examiners evaluated the images and scored the conspicuity of the acute lesions. Results: Regardless of location, FLAIR provided the best lesion conspicuity in the detection of acute infarcts, followed by the GRASE sequence. In the posterior fossa, TSE and SE demonstrated the lesions better than GRASE and FLAIR techniques. In the detection of hemorrhagic elements within the ischemic region, TSE demonstrated statistically significant superiority over other sequences. Conclusion: In the detection of acute ischemic lesions in locations other than the posterior fossa, FLAIR provided the best lesion conspicuity among four T2-weighted sequences, including SE, TSE, GRASE and FLAIR. However, for the posterior fossa examination, preference of SE or TSE T2-weighted sequences is suggested.

  10. Classifying galaxy spectra at 0.5 < z < 1 with self-organizing maps

    Science.gov (United States)

    Rahmani, S.; Teimoorinia, H.; Barmby, P.

    2018-05-01

    The spectrum of a galaxy contains information about its physical properties. Classifying spectra using templates helps elucidate the nature of a galaxy's energy sources. In this paper, we investigate the use of self-organizing maps in classifying galaxy spectra against templates. We trained semi-supervised self-organizing map networks using a set of templates covering the wavelength range from far ultraviolet to near infrared. The trained networks were used to classify the spectra of a sample of 142 galaxies with 0.5 K-means clustering, a supervised neural network, and chi-squared minimization. Spectra corresponding to quiescent galaxies were more likely to be classified similarly by all methods while starburst spectra showed more variability. Compared to classification using chi-squared minimization or the supervised neural network, the galaxies classed together by the self-organizing map had more similar spectra. The class ordering provided by the one-dimensional self-organizing maps corresponds to an ordering in physical properties, a potentially important feature for the exploration of large datasets.

  11. Fluid flow in 0.5-m scale blocks of Topopah Spring tuff

    International Nuclear Information System (INIS)

    Blair, S. C.; Carlson, S. R.; Constantino, M. S.

    1999-01-01

    A laboratory experiment was conducted on a 0.5-m scale block of Topopah Spring tuff, to measure fluid flow and mechanical deformation properties under conditions that approximate the near-field environment of a potential nuclear waste repository, and to provide an intermediate-scale test case for numerical model validation. The test specimen is a 0.25 x 0.25 x 0.50 m rectangular prism bisected by an artificial (saw-cut) fracture orthogonal to the tuff fabric. Water was supplied by a point source at the center of the fracture under various pressures of up to 0.04 MPa. Both fluid flow and mechanical properties were found to be anisotropic and strongly correlated with the ash flow fabric. Fluid mass-balance measurements revealed that only minor imbibition of water occurred through the fracture surfaces and that flow rates were independent of normal stress to 14.0 MPa and temperature to 140 C. Flow through the fracture occurred largely through uncorrelated porosity that intersected the fracture plane

  12. Crystal structure and optical absorption spectra of Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} and Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3} crystals; Struktura i opticheskoe pogloshchenie kristallov Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} i Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Gusejnov, G G; Musaeva, N N; Kyazumov, M G [NAN Azerbajdzhana, Inst. Fiziki, Baku (Azerbaijan); Asadova, I B; Aliev, O M [NAN Azerbajdzhana, Inst. Neorganicheskoj i Fizicheskoj Khimii, Baku (Azerbaijan)

    2003-09-01

    Single crystals of Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} are grown by the method of chemical gas-transport reactions and those of Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3} - by Bridgman method. X-ray diffraction studies reveal that they crystallize in trigonal and rhombohedral systems with lattice parameters of a = 3.796 x 2 A, c = 12.210 A, P3m1; a = 3.786 x 2 A, c = 36.606 A, R3m, respectively. An optical absorption edge in a wide range of photon energy and an energy gap width are determined: E{sub g} = 1.885 eV for Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} and E{sub g} 1.843 eV for Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3}.

  13. Effects of Nb doping level on the electronic transport, photoelectric effect and magnetoresistance across La0.5Ca0.5MnO3/Nb:SrTiO3 junctions

    Science.gov (United States)

    Wang, J. F.; Jiang, Y. C.; Chen, M. G.; Gao, J.

    2013-12-01

    Heterojunctions composed of La0.5Ca0.5MnO3 and Nb doped SrTiO3 were fabricated, and the effects of the Nb doping level on their electronic transport, photoelectric effect, and magnetoresistance were investigated. A lower doping concentration of Nb led to better rectifying properties and higher open circuit voltages. The I-V curves for La0.5Ca0.5MnO3/0.7 wt. % Nb-SrTiO3 showed a negligible response to magnetic fields for all temperatures, whereas La0.5Ca0.5MnO3/0.05 wt. % Nb-SrTiO3 exhibited distinct magnetoresistance, which depended on both the bias voltage and temperature. These results are discussed with the assistance of conventional semiconductor theories.

  14. PHASE EVOLUTION AND MICROWAVE DIELECTRIC PROPERTIES OF (Li0.5Bi0.5)(W1-xMox)O4(0.0 ≤ x ≤ 1.0) CERAMICS WITH ULTRA-LOW SINTERING TEMPERATURES

    Science.gov (United States)

    Zhou, Di; Guo, Jing; Yao, Xi; Pang, Li-Xia; Qi, Ze-Ming; Shao, Tao

    2012-11-01

    The (Li0.5Bi0.5)(W1-xMox)O4(0.0 ≤ x ≤ 1.0) ceramics were prepared via the solid state reaction method. The sintering temperature decreased almost linearly from 755°C for (Li0.5Bi0.5)WO4 to 560°C for (Li0.5Bi0.5)MoO4. When the x≤0.3, a wolframite solid solution can be formed. For x = 0.4 and x = 0.6 compositions, both the wolframite and scheelite phases can be formed from the X-ray diffraction analysis, while two different kinds of grains can be revealed from the scanning electron microscopy and energy-dispersive X-ray spectrometer results. High performance of microwave dielectric properties were obtained in the (Li0.5Bi0.5)(W0.6Mo0.4)O4 ceramic sintered at 620°C with a relative permittivity of 31.5, a Qf value of 8500 GHz (at 8.2 GHz), and a temperature coefficient value of +20 ppm/°C. Complex dielectric spectra of pure (Li0.5Bi0.5)WO4 ceramic gained from the infrared spectra were extrapolated down to microwave range, and they were in good agreement with the measured values. The (Li0.5Bi0.5)(W1-xMox)O4(0.0 ≤ x ≤ 1.0) ceramics might be promising for low temperature co-fired ceramic technology.

  15. Structural and Moessbauer Effect Studies of 0.7Bi0.95Dy0.05FeO3-0.3Pb(Fe0.5Nb0.5)O3 Multiferroic

    International Nuclear Information System (INIS)

    Stoch, A.; Kulawik, J.; Stoch, P.; Maurin, J.; Zachariasz, P.

    2011-01-01

    0.7Bi 0.95 Dy 0.05 FeO 3 -0.3Pb(Fe 0.5 Nb 0.5 )O 3 is a multiferroic material which exhibits ferroelectric and antiferromagnetic ordering. In this paper the way of the synthesis of 0.7Bi 0.95 Dy 0.05 FeO 3 -0.3Pb(Fe 0.5 Nb 0.5 )O 3 is presented. The detailed X-ray and Moessbauer effect studies were done and crystal and hyperfine interaction parameters were obtained. (authors)

  16. Deformation-induced structural changes of amorphous Ni{sub 0.5}Zr{sub 0.5} in molecular-dynamic simulations; Verformungsinduzierte Strukturaenderungen bei amorphen Ni{sub 0.5}Zr{sub 0.5} in Molekulardynamik-Simulationen

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, K

    2006-10-31

    The present work investigates the plastic deformation of metallic glasses by the aid of molecular-dynamic simulations. The parameters for the model system are adapted to those for a NiZr-alloy. In particular, the composition Ni{sub 0.5}Zr{sub 0.5} is used. The analyzed deformation simulations are conducted for small systems with 5184 atoms and large systems with 17500 atoms in a periodic simulation cell. The deformation simulations of pre-deformed samples are carried out either at constant shear-rate or at constant load, the latter mode modeling a creep experiment. Stress-strain curves for pre-deformed samples show a less pronounced stress-overshoot phenomenon. Creep-simulations of samples deformed beyond the yield region indicate a drastically reduced viscosity in these systems when compared to samples pre-deformed only up to the linear regime of the stress-strain curve. From analyzing the local atomic topology it is found that the transition from the highly viscous, hard-to-deform state of the undeformed or only weakly strained system into the easy-to-deform flow-state, present if the system is strained far beyond the yielding regime of the stress-strain curve, is connected with the formation of a region containing atoms with massive changes in their topology which is oriented along a diagonal plane of the simulation cell. The degree of localization of these deformation bands is influenced by temperature and shear-rate. In subsequent deformations of pre-deformed samples the regions with massive changes in the atomic topology are again susceptible to changes in the local atomic topology. By using methods from statistics, a significant difference in the distribution of atomic properties for the group of atoms with massive topology changes on the one hand and the group of atoms without changes in their topology on the other gets quantitatively ascertainable. From the differences in structural properties, e.g. potential energy, cage volumes, angular order parameters

  17. Histological studies in developing brain after 0.5 Gy neutron irradiation in utero

    International Nuclear Information System (INIS)

    Antal, S.; Fueloep, Z.

    1986-01-01

    Pregnant mice were irradiated with 0.5 Gy neutrons on day 13, 15 or 18 of gestation. There was no significant difference in number of living young born per litter between in neutron irradiated mice and controls. Mortality of irradiated offspings increased in the first 3 days after birth. The brain weight of 21-day old animals after neutron irradiation averaged only 55, 56 and 69% of controls, resp. At six hours after irradiation morphological analysis showed nuclear pyknosis in the central nervous system. On day 13 the telencephalon was severely affected. The 30% cells were pyknotic in the wall of the cerebral hemisphere and 20% of cells in corpus striatum. In the metencephalon marked pyknosis was established in the tectal lamina of mesencephalon (16%) and in the cerebellar anlage (21%). The olfactory plate (24%), the ventricular zone of cerebral hemisphere (30%) and colliculus ganglionaris were damaged mostly (40%) after radiation on day 15 of gestation. The tectum of the mesencephali and in metencephalon the external granular layer of cerebellum and area of the rhombic lip were affected by irradiation (17-20%). The telencephalon found pyknotic but to a less extent in group irradiated on day 18 than it was on day 15. In the olfactory bulb 10% of pyknotic cells were seen and 16% of primary cortex of cerebral hemisphere more over 30% of nucleus caudatus/putamen were affected. In metencephalon 19% of external granular layer of cerebellum and 13% of trigonum cerebelli were pyknotic. In general, lesions of irradiation were rather mild in diencephalon and myelencephalon at all examined ages. Histological examinations support that defined parts of brain are damaged after neutron irradiation in utero and it may lead to the described physiological 18-20 and biochemical consequences 20,23 . (orig.)

  18. Early diagnosis of ischemic cerebrovascular diseases by means of 0. 5 Tesla MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Akira; Hirose, Genjiro; Kataoka, Satoshi; Tsukada, Katsuyuki; Oda, Rokuhei; Ito, Masami

    1988-08-01

    15 patients with cerebral infarctions involving major vessels, such as internal carotid and middle cerebral arteries, were studied sequentially with a 0.5 Tesla superconductive MRI system from a few hours after the insults up to 3 months. Within 24 hours after the events, high-signal areas were detected in 13 of the 15 cases by the use of T/sub 2/-weighted images. The high-signal areas were noted in two out of three cases even within 3 hours, and in one out of two within six hours, after the cerebrovascular accidents, whereas no abnormalities were noted by conventional CT scans within the same times. There was a tendency for the high-signal areas to be localized in the cortical and deep gray matter within 24 hours and to extend into the deep white matter during the following 24 hours. It was suggested that the localization of high-signal areas in the gray matter in the early ischemic phase could be due to cytotoxic edema and that there was a different vulnerability to ischemia between gray and white matter. At 2 weeks after the accidents, a ''fogging effect'' was noted in five out of the eight cases which were sequentially evaluated by MRI. MRI was superior to CT scan in the visualization of this ''fogging effect''. All of the 5 cases with cortical-subcortical infarctions showed the ''fogging effect'', whereas 3 cases with deep gray matter infarctions, in which the collateral circulation was poor angiographically, did not show such a phenomenon. The CT scans revealed no findings which suggested a hemorrhagic infarction in any of the 5 cases with the ''fogging effect''. These findings suggested that the ''fogging effect'' could represent the reflow phenomenon from collateral circulations.

  19. The early diagnosis of ischemic cerebrovascular diseases by means of 0.5 Tesla MRI

    International Nuclear Information System (INIS)

    Yoshioka, Akira; Hirose, Genjiro; Kataoka, Satoshi; Tsukada, Katsuyuki; Oda, Rokuhei; Ito, Masami

    1988-01-01

    15 patients with cerebral infarctions involving major vessels, such as internal carotid and middle cerebral arteries, were studied sequentially with a 0.5 Tesla superconductive MRI system from a few hours after the insults up to 3 months. Within 24 hours after the events, high-signal areas were detected in 13 of the 15 cases by the use of T 2 -weighted images. The high-signal areas were noted in two out of three cases even within 3 hours, and in one out of two within six hours, after the cerebrovascular accidents, whereas no abnormalities were noted by conventional CT scans within the same times. There was a tendency for the high-signal areas to be localized in the cortical and deep gray matter within 24 hours and to extend into the deep white matter during the following 24 hours. It was suggested that the localization of high-signal areas in the gray matter in the early ischemic phase could be due to cytotoxic edema and that there was a different vulnerability to ischemia between gray and white matter. At 2 weeks after the accidents, a ''fogging effect'' was noted in five out of the eight cases which were sequentially evaluated by MRI. MRI was superior to CT scan in the visualization of this ''fogging effect''. All of the 5 cases with cortical-subcortical infarctions showed the ''fogging effect'', whereas 3 cases with deep gray matter infarctions, in which the collateral circulation was poor angiographically, did not show such a phenomenon. The CT scans revealed no findings which suggested a hemorrhagic infarction in any of the 5 cases with the ''fogging effect''. These findings suggested that the ''fogging effect'' could represent the reflow phenomenon from collateral circulations. (author)

  20. The rest-frame ultraviolet structure of 0.5 < z < 1.5 galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Nicholas A.; Gardner, Jonathan P. [Cosmology Laboratory (Code 665), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); De Mello, Duilia F. [Physics Department, The Catholic University of America, Washington, DC 20064 (United States); Teplitz, Harry I.; Rafelski, Marc [IPAC, California Institute of Technology, Pasadena, CA 91125 (United States); Koekemoer, Anton M.; Coe, Dan; Grogin, Norman [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gawiser, Eric [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Ravindranath, Swara [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Scarlata, Claudia [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2014-08-10

    We present the rest-frame UV wavelength dependence of the Petrosian-like half-light radius (r{sub 50}), and the concentration parameter for a sample of 198 star-forming galaxies at 0.5 < z < 1.5. We find a ∼5% decrease in r{sub 50} from 1500 Å to 3000 Å, with half-light radii at 3000 Å ranging from 0.6 kpc to 6 kpc. We also find a decrease in concentration of ∼0.07 (1.9 < C{sub 3000} < 3.9). The lack of a strong relationship between r{sub 50} and wavelength is consistent with a model in which clumpy star formation is distributed over length scales comparable to the galaxy's rest-frame optical light. While the wavelength dependence of r{sub 50} is independent of size at all redshifts, concentration decreases more sharply in the far-UV (∼1500 Å) for large galaxies at z ∼ 1. This decrease in concentration is caused by a flattening of the inner ∼20% of the light profile in disk-like galaxies, indicating that the central regions have different UV colors than the rest of the galaxy. We interpret this as a bulge component with older stellar populations and/or more dust. The size-dependent decrease in concentration is less dramatic at z ∼ 2, suggesting that bulges are less dusty, younger, and/or less massive than the rest of the galaxy at higher redshifts.

  1. NuSTAR Reveals Extreme Absorption in z < 0.5 Type 2 Quasars

    Science.gov (United States)

    Lansbury, G. B.; Gandhi, P.; Alexander, D. M.; Assef, R. J.; Aird, J.; Annuar, A.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Civano, F.; Comastri, A.; Craig, W. W.; Del Moro, A.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Koss, M.; LaMassa, S. M.; Luo, B.; Puccetti, S.; Stern, D.; Treister, E.; Vignali, C.; Zappacosta, L.; Zhang, W. W.

    2015-08-01

    The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end of the quasar population and for redshifts z 1.5 × 1024 cm-2) type 2 quasars (CTQSO2s); five new NuSTAR observations are reported herein, and four have been previously published. The candidate CTQSO2s lie at z < 0.5, have observed [O iii] luminosities in the range 8.4\\lt {log}({L}[{{O} {{III}}]}/{L}⊙ )\\lt 9.6, and show evidence for extreme, Compton-thick absorption when indirect absorption diagnostics are considered. Among the nine candidate CTQSO2s, five are detected by NuSTAR in the high-energy (8-24 keV) band: two are weakly detected at the ≈3σ confidence level and three are strongly detected with sufficient counts for spectral modeling (≳90 net source counts at 8-24 keV). For these NuSTAR-detected sources direct (i.e., X-ray spectral) constraints on the intrinsic active galactic nucleus properties are feasible, and we measure column densities ≈2.5-1600 times higher and intrinsic (unabsorbed) X-ray luminosities ≈10-70 times higher than pre-NuSTAR constraints from Chandra and XMM-Newton. Assuming the NuSTAR-detected type 2 quasars are representative of other Compton-thick candidates, we make a correction to the NH distribution for optically selected type 2 quasars as measured by Chandra and XMM-Newton for 39 objects. With this approach, we predict a Compton-thick fraction of {f}{CT}={36}-12+14 %, although higher fractions (up to 76%) are possible if indirect absorption diagnostics are assumed to be reliable.

  2. NEW OBSERVATIONS OF THE SOLAR 0.5–5 KEV SOFT X-RAY SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, Amir; Woods, Thomas N. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Warren, Harry P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2015-03-20

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ∼0.2 and ∼4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ∼0.5 to ∼5 keV, with ∼0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5–10 MK) emission and are well fit by simple power-law temperature distributions with indices of ∼6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ∼1.6, below the usually observed value of ∼4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.

  3. Dust Attenuation and H(alpha) Star Formation Rates of Z Approx. 0.5 Galaxies

    Science.gov (United States)

    Ly, Chun; Malkan, Matthew A.; Kashikawa, Nobunari; Ota, Kazuaki; Shimasaku, Kazuhiro; Iye, Masanori; Currie, Thayne

    2012-01-01

    Using deep narrow-band and broad-band imaging, we identify 401 z approximately 0.40 and 249 z approximately 0.49 H-alpha line-emitting galaxies in the Subaru Deep Field. Compared to other H-alpha surveys at similar redshifts, our samples are unique since they probe lower H-alpha luminosities, are augmented with multi-wavelength (rest-frame 1000AA--1.5 microns) coverage, and a large fraction (20%) of our samples has already been spectroscopically confirmed. Our spectra allow us to measure the Balmer decrement for nearly 60 galaxies with H-beta detected above 5-sigma. The Balmer decrements indicate an average extinction of A(H-alpha)=0.7(uparrow){+1.4}_{-0.7} mag. We find that the Balmer decrement systematically increases with higher H-alpha luminosities and with larger stellar masses, in agreement with previous studies with sparser samples. We find that the SFRs estimated from modeling the spectral energy distribution (SED) is reliable---we derived an "intrinsic" H-alpha luminosity which is then reddened assuming the color excess from SED modeling. The SED-predicted H-alpha luminosity agrees with H-alpha narrow-band measurements over 3 dex (rms of 0.25 dex). We then use the SED SFRs to test different statistically-based dust corrections for H-alpha and find that adopting one magnitude of extinction is inappropriate: galaxies with lower luminosities are less reddened. We find that the luminosity-dependent dust correction of Hopkins et al. yields consistent results over 3 dex (rms of 0.3 dex). Our comparisons are only possible by assuming that stellar reddening is roughly half of nebular reddening. The strong correspondence argue that with SED modeling, we can derive reliable intrinsic SFRs even in the absence of H-alpha measurements at z approximately 0.5.

  4. High current, 0.5-MA, fast, 100-ns, linear transformer driver experiments

    Directory of Open Access Journals (Sweden)

    Michael G. Mazarakis

    2009-05-01

    Full Text Available The linear transformer driver (LTD is a new method for constructing high current, high-voltage pulsed accelerators. The salient feature of the approach is switching and inductively adding the pulses at low voltage straight out of the capacitors through low inductance transfer and soft iron core isolation. Sandia National Laboratories are actively pursuing the development of a new class of accelerator based on the LTD technology. Presently, the high current LTD experimental research is concentrated on two aspects: first, to study the repetition rate capabilities, reliability, reproducibility of the output pulses, switch prefires, jitter, electrical power and energy efficiency, and lifetime measurements of the cavity active components; second, to study how a multicavity linear array performs in a voltage adder configuration relative to current transmission, energy and power addition, and wall plug to output pulse electrical efficiency. Here we report the repetition rate and lifetime studies performed in the Sandia High Current LTD Laboratory. We first utilized the prototype ∼0.4-MA, LTD I cavity which could be reliably operated up to ±90-kV capacitor charging. Later we obtained an improved 0.5-MA, LTD II version that can be operated at ±100  kV maximum charging voltage. The experimental results presented here were obtained with both cavities and pertain to evaluating the maximum achievable repetition rate and LTD cavity performance. The voltage adder experiments with a series of double sized cavities (1 MA, ±100  kV will be reported in future publications.

  5. Synthesis, magnetization and photocatalytic activity of LaFeO{sub 3} and LaFe{sub 0.5}Mn{sub 0.5-x}O{sub 3-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Zhi-Xian, E-mail: zx_wei@126.com [Beijing Institute of Protective Materials and Technology, Beijing 100081 (China); School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Department of Chemistry, Science Institute, North University of China, Taiyuan, Shanxi 030051 (China); Wang, Yan [Department of Chemistry, Chengde Teachers College for Nationalities, Chengde, Hebei 067000 (China); Liu, Ji-Ping, E-mail: liujp@bit.edu.cn [Beijing Institute of Protective Materials and Technology, Beijing 100081 (China); School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xiao, Cai-Mei; Zeng, Wei-Wei [Department of Chemistry, Science Institute, North University of China, Taiyuan, Shanxi 030051 (China)

    2012-10-15

    Perovskite LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} and LaFeO{sub 3} were synthesized by stearic acid solution combustion method. The obtained powders were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Vibrating sample magnetometer (VSM), XPS techniques and UV-vis absorption spectra techniques. The magnetic properties of the LaFeO{sub 3} and LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were measured, and they were also evaluated for their photocatalytic activity towards the degradation of methyl orange (MO) under the sunlight irradiation. The experimental results show that the catalytic activities of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were much higher than those of LaFeO{sub 3} due to its higher oxygen vacancies, variable valency Mn ions and the strong absorption in visible light. The optimum conditions for photocatalytic degradation MO using LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} were achieved. The ferromagnetism of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} could be caused by the Mn{sup 3+}/Fe{sup 3+} and Mn{sup 3+}/Mn{sup 4+}double exchange interaction, Mn{sup 3+}/Mn{sup 3+} superexchange interactions as well as the defective state in LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}}. The LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is applicable to the magnetic separation process for its lower coercivity (Hc) and remanent magnetization (Mr), and it can be reusable and maintain relatively high activity. -- Highlights: Black-Right-Pointing-Pointer The LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is a bifunctional photocatalyst. Black-Right-Pointing-Pointer The origin of the ferromagnetism of the LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} is discussed. Black-Right-Pointing-Pointer LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} shows much higher photocatalytic activity than that of LaFeO{sub 3.} Black-Right-Pointing-Pointer LaFe{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} can be recycled by an external magnetic

  6. Effect of Tb and Al substitution within the rare earth and cobalt sublattices on magnetothermal properties of Dy{sub 0.5}Ho{sub 0.5}Co{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Chzhan, V.B., E-mail: lemuriform@gmail.com [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119334 (Russian Federation); National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Tereshina, E.A. [Institute of Physics CAS, Prague 18221 (Czech Republic); Mikhailova, A.B. [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119334 (Russian Federation); Politova, G.A. [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119334 (Russian Federation); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421 (Poland); Tereshina, I.S. [Baikov Institute of Metallurgy and Material Sciences, Russian Academy of Sciences, Moscow 119334 (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Kozlov, V.I. [Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Ćwik, J. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53-421 (Poland); Nenkov, K. [IFW Dresden, P.O. Box 270116, 01171 Dresden (Germany); Alekseeva, O.A.; Filimonov, A.V. [Peter the Great St. Petersburg Polytechnic University, St. Petersburg 195251 (Russian Federation)

    2017-06-15

    Highlights: • Single-phase (Tb,Dy,Ho)(Co,Al){sub 2} alloys synthesized using high-purity metals. • Temperature dependence of lattice parameters measured in a wide temperature range. • Tb and Al substitution increase the Curie temperature in Dy{sub 0.5}Ho{sub 0.5}Co{sub 2.} • The MCE measured by direct and indirect methods. • Materials with ‘table-like’ MCE are found. - Abstract: The effect of Tb and Al substitution within the rare earth and cobalt sublattices on structural and magnetothermal properties of Dy{sub 0.5}Ho{sub 0.5}Co{sub 2} has been studied. Multicomponent Laves phase alloys Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 2−y}Al{sub y} (x = 0, 0.3, 0.4, 0.5; y = 0, 0.25) synthesized using high-purity metals have been studied using X-ray diffraction analysis, heat capacity and magnetocaloric measurements. Dy{sub 0.5}Ho{sub 0.5}Co{sub 2} has a first order phase transition at the Curie temperature T{sub C} ≈ 110 K. Both Tb and Al substitution leads to increase of the T{sub C}. The increasing Tb content leads to the decreases slightly the MCE and all the transitions near the Curie temperature are of the first order. As for the Al-containing compounds, MCE measurements show that the phase transition type changes from the first to the second-order. The advantage of Tb{sub x}(Dy{sub 0.5}Ho{sub 0.5}){sub 1−x}Co{sub 1.75}Al{sub 0.25} as compared with Al-free alloys is ‘table-like’ behavior of MCE.

  7. [Orthodontic treatment of malocclusion Class III in patients aged 6-12 by Postnikov appliance, face mask and bracket system].

    Science.gov (United States)

    Postnikov, M A; Trunin, D A; Pankratova, N V; Nesterov, A M; Sadykov, M I; Ostankov, S A

    2018-01-01

    The diagnostics and treatment of malocclusion Class III in patients aged 6-12 is an vital problem in orthodontics. Method of orthodontic treatment of malocclusion Class III in patients with the help of improved and patented orthodontic construction - 'Postnikov appliance' - and face mask and bracket system is analysed in the article. Orthodontic treatment of malocclusion Class III was examined in 24 patients aged 6-12 by the suggested method. All patients were examined clinically and with the help af additional diagnostic methods: head cephalometry in lateral position with further data analysis in Dolphin Imaging (USA). The use of computer technologies in Dolphin Imaging helps to controll the process of correction of dentition correlation in different stages of treatment, to reduce the period of treatment of malocclusion Class III in patients aged 6-12 and to improve face esthetics and life quality ratio.

  8. Rapid detection of the CYP2A6*12 hybrid allele by Pyrosequencing® technology

    Directory of Open Access Journals (Sweden)

    Gallagher Margaret L

    2009-08-01

    Full Text Available Abstract Background Identification of CYP2A6 alleles associated with reduced enzyme activity is important in the study of inter-individual differences in drug metabolism. CYP2A6*12 is a hybrid allele that results from unequal crossover between CYP2A6 and CYP2A7 genes. The 5' regulatory region and exons 1–2 are derived from CYP2A7, and exons 3–9 are derived from CYP2A6. Conventional methods for detection of CYP2A6*12 consist of two-step PCR protocols that are laborious and unsuitable for high-throughput genotyping. We developed a rapid and accurate method to detect the CYP2A6*12 allele by Pyrosequencing technology. Methods A single set of PCR primers was designed to specifically amplify both the CYP2A6*1 wild-type allele and the CYP2A6*12 hybrid allele. An internal Pyrosequencing primer was used to generate allele-specific sequence information, which detected homozygous wild-type, heterozygous hybrid, and homozygous hybrid alleles. We first validated the assay on 104 DNA samples that were also genotyped by conventional two-step PCR and by cycle sequencing. CYP2A6*12 allele frequencies were then determined using the Pyrosequencing assay on 181 multi-ethnic DNA samples from subjects of African American, European Caucasian, Pacific Rim, and Hispanic descent. Finally, we streamlined the Pyrosequencing assay by integrating liquid handling robotics into the workflow. Results Pyrosequencing results demonstrated 100% concordance with conventional two-step PCR and cycle sequencing methods. Allele frequency data showed slightly higher prevalence of the CYP2A6*12 allele in European Caucasians and Hispanics. Conclusion This Pyrosequencing assay proved to be a simple, rapid, and accurate alternative to conventional methods, which can be easily adapted to the needs of higher-throughput studies.

  9. Electrical and structural properties of La0.8Sr0.2Mn0.5Co0.5O3±δ films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Christensen, Bo Toftmann; Schou, Jørgen

    2005-01-01

    La0.8Sr0.2Mn0.5Co0.5O3 (LSMCO) films for the use as contact layers or protective coatings in solid oxide fuel cells (SOFC) have been deposited on glass substrates by pulsed laser deposition (PLD). PLD is an obvious technique for thin film production of complex oxides, because of the ability...

  10. Effects of processing parameters on the synthesis of (K0.5Na0.5)NbO3 nanopowders by reactive high-energy ball milling method.

    Science.gov (United States)

    Nguyen, Duc Van

    2014-01-01

    The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C.

  11. Visualization of the Diffusion Pathway of Protons in (NH4)2Si0.5Ti0.5P4O13 as an Electrolyte for Intermediate-Temperature Fuel Cells.

    Science.gov (United States)

    Sun, Chunwen; Chen, Lanli; Shi, Siqi; Reeb, Berthold; López, Carlos Alberto; Alonso, José Antonio; Stimming, Ulrich

    2018-01-16

    We demonstrate that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is an excellent proton conductor. The crystallographic information concerning the hydrogen positions is unraveled from neutron-powder-diffraction (NPD) data for the first time. This study shows that all the hydrogen atoms are connected though H bonds, establishing a two-dimensional path between the [(Si 0.5 Ti 0.5 )P 4 O 13 2- ] n layers for proton diffusion across the crystal structure by breaking and reconstructing intermediate H-O═P bonds. This transient species probably reduces the potential energy of the H jump from an ammonium unit to the next neighboring NH 4 + unit. Both theoretical and experimental results support an interstitial-proton-conduction mechanism. The proton conductivities of (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 reach 0.0061 and 0.024 S cm -1 in humid air at 125 and 250 °C, respectively. This finding demonstrates that (NH 4 ) 2 Si 0.5 Ti 0.5 P 4 O 13 is a promising electrolyte material operating at 150-250 °C. This work opens up a new avenue for designing and fabricating high-performance inorganic electrolytes.

  12. Moderate Malnutrition in Children Aged 0-5 in the Republic of Macedonia

    International Nuclear Information System (INIS)

    Spiroski, Igor; Memeti, Shaban

    2014-01-01

    Full text: Background: Undernutrition indicates a lack of the necessary energy, macro or micronutrients in person’s dietary intake. FAO reported that one in seven people in the world do not get enough food to be healthy and lead an active life. The objective of our survey was to assess the prevalence of undernutrition among children aged 0-5 in Macedonia. Methods: Nationally representative household survey was conducted and data for 1376 children under the age of 5 was gathered. The survey included two samples, one for general population and separate one for Roma population living in Roma settlements. Roma children had higher prevalence of undernutrition in previous surveys. The data was gathered in the frames of UNICEF’s Multiple Indicator Cluster survey in 2011. WHO Child Growth Standards were used to assess the nutritional status. Results: Out of general sample children 4.9% were moderately stunted (between -3 and -2 z-scores of height-for-age index), 5.6% boys and 4.3% girls. The percentage of moderately stunted children was over three times higher in the poorest wealth quintile compared to the richest one (7.2% and 2.0% respectively). In general population of children 1.8% were moderately wasted (between -3 and -2 z-scores of weight-for-height index), 2.2% boys and 1.4% girls. Wasting was also 3 times more prevalent in children from the poorest households compared to the richest ones (3.5% and 0.6% respectively). As for the Roma children, 16.5% of them were moderately stunted (21.1% boys, 12% girls) and 4.5% moderately wasted (4.3% boys, 4.7% girls). Nearly 10 times more moderately stunted Roma children were present in the poorest wealth quintile compared to the richest one (28.7% and 3.5% respectively). Conclusions: The results of the survey indicate low prevalence of undernutrition in the general population of children under 5 years of age in Macedonia which is in acceptable ranges defined by the WHO (<20% for stunting, <5% for wasting). Results for the

  13. In situ X-ray diffraction characterisation of Fe0.5TiOPO4 and Cu0.5TiOPO4 as electrode material for sodium-ion batteries

    International Nuclear Information System (INIS)

    Bleith, Peter; Kaiser, Hermann; Novák, Petr; Villevieille, Claire

    2015-01-01

    Na-ion batteries might become a low-cost alternative to Li-ion batteries in the future. Suitable electrode materials, especially anode materials, are needed for Na-ion batteries. As possible candidates Cu 0.5 TiOPO 4 and Fe 0.5 TiOPO 4 were tested. While Cu 0.5 TiOPO 4 does not react with Na + , Fe 0.5 TiOPO 4 shows a specific charge of ≈600 mAh/g upon the first sodiation and 280 mAh/g in the first desodiation. In situ XRD in a new, versatile and reliable in situ cell revealed that Fe 0.5 TiOPO 4 reacts via a conversion type reaction upon sodiation with an amorphisation of the sample

  14. Structural change of Li{sub 1-x}Ni{sub 0.5}Mn{sub 0.5}O{sub 2} cathode materials for lithium-ion batteries by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Arachi, Yoshinori; Tanaka, Minoru; Asai, Takeshi [Kansai Univ., Faculty of Engineering, Unit of Chemistry, Suita, Osaka (Japan); Kobayashi, Hironori [National Inst. of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka (Japan); Emura, Shuichi [Osaka Univ., ISIR, Ibaraki, Osaka (Japan); Nakata, Yoshiyuki [Iwakimeisei Univ., Faculty of Science and Engineering, Iwaki, Fukushima (Japan)

    2003-01-01

    Synchrotron X-ray diffraction and XAFS measurement have been employed to investigate structural change and the charging process of a layered LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} cathode material. The structure of charged Li{sub 1-x}Ni{sub 0.5}Mn{sub 0.5}O{sub 2} (x = 0.5), which corresponds to the composition for showing rechargeable capacity, was determined. The results showed that divalent nickel metal was oxidized to trivalent after charging, in association with the phase transition from hexagonal (R3-bar m) to monoclinic (C2/m) resulting from the ordering of cations in the layered structure. (author)

  15. The photoluminescent property and optical transition analysis of host sensitized Ca{sub 0.5}Sr{sub 0.5}MoO{sub 4}:Dy{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhiping; Hou, Chuncai [College of Physics and Technology, Hebei University, Baoding, Hebei 071002 (China); Duan, Guangjie [College of Electronics and Information Engineering, Hebei University, Baoding, Hebei 071002 (China); Yang, Fu [College of Physics and Technology, Hebei University, Baoding, Hebei 071002 (China); College of Science, Hebei North University, Zhangjiakou 075000 (China); Liu, Pengfei; Wang, Can [College of Physics and Technology, Hebei University, Baoding, Hebei 071002 (China); Liu, Lipeng [College of Electronics and Information Engineering, Hebei University, Baoding, Hebei 071002 (China); Dong, Guoyi, E-mail: dongguoyitxzz@163.com [College of Physics and Technology, Hebei University, Baoding, Hebei 071002 (China)

    2014-08-01

    Highlights: • A novel host sensitized Ca{sub 0.5−x}Sr{sub 0.5}MoO{sub 4}:xDy{sup 3+} phosphors could be synthesized by solid state reaction. • The XRD and SEM figures were made to analyze the crystal phase and morphology of Ca{sub 0.5−x}Sr{sub 0.5}MoO{sub 4}:xDy{sup 3+} phosphors. • We research the emission and excitation properties by analyzing the relevant optical transition. • The energy transition is proved to exist by the analysis on luminescence spectra and luminescence decay curves. • The chromaticity coordinate of Ca{sub 0.5−x}Sr{sub 0.5}MoO{sub 4}:xDy{sup 3+} will be tunable as changing x. - Abstract: A series of Dy{sup 3+} doped Ca{sub 0.5}Sr{sub 0.5}MoO{sub 4} phosphors were synthesized by solid state reaction. The structure and the photoluminescent (PL) properties of the as-prepared powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscope and fluorescent spectrophotometry. The analyses on optical transition of Ca{sub 0.5}Sr{sub 0.5}MoO{sub 4}:xDy{sup 3+} phosphors indicate that the broad band of excitation spectrum comes from the charge transmission. The broad band of excitation spectrum matches well with the excitation energy level of Dy{sup 3+}, indicating the energy transfer from the host to Dy{sup 3+}. The chromaticity coordinates changed from blue–green to yellow area depending on the Dy{sup 3+} concentration. In addition, the main mechanism of the concentration quenching was the electric multiple interaction between Dy{sup 3+} ions.

  16. Structural and Mössbauer spectroscopy characterization of bulk and nanostructured TiFe{sub 0.5} Ni{sub 0.5}/graphite compounds and their hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, M. A. R., E-mail: fisicorodriguez@gmail.com; André-Filho, J.; Félix, L. L.; Coaquira, J. A. H.; Garg, V. K.; Oliveira, A. C. [Universidade de Brasília, Instituto de Física, Núcleo de Física Aplicada (Brazil); Mestnik-Filho, J. [Instituto de Pesquisas energéticas e Nucleares, IPEN-CNEN/SP (Brazil)

    2015-06-15

    The structural and hyperfine properties of bulk TiFe{sub 0.5}Ni{sub 0.5} intermetallic and ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite compounds and their hydrides have been studied. The bulk and nanostructured TiFe{sub 0.5}Ni{sub 0.5} compounds crystallize in the cubic crystal structure of CsCl (B2). After hydrogenation, the formation of hydrogen-poor phase (∝-phase) and hydride phase (β-phase) have been determined for the bulk compound. However, the formation of the ∝-phase and the hydrogen-richest phase (γ-phase) and other secondary phases have been determined for the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample. It has been determined that the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample presents a large amount of the γ-phase which indicates that the presence of graphite nearby nanostructured intermetallic grains enhances the absorption of hydrogen. Mossbauer results are consistent with the structural results. Meanwhile, no significant changes in the isomer shift (IS) value has been determined for the α-phase with respect to the intermetallic compound, a strong increase in the IS value has been determined for the β- and γ-phases with respect to the ∝-phase. That increase indicates a decrease of the s-electron density at the Fe nuclei due to the charge transfer from the metal to the nearby hydrogen atoms.

  17. 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.)

  18. Polyethylene imine-grafted ACF@BiOI{sub 0.5}Cl{sub 0.5} as a recyclable photocatalyst for high-efficient dye removal by adsorption-combined degradation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongyan [Collaborative Innovation Center of Suzhou Nano Science and Technology, College of Chemistry, Chemical Engineering and Materials Science, Suzhou University, Suzhou, Jiangsu 215123 (China); Li, Najun, E-mail: linajun@suda.edu.cn [Collaborative Innovation Center of Suzhou Nano Science and Technology, College of Chemistry, Chemical Engineering and Materials Science, Suzhou University, Suzhou, Jiangsu 215123 (China); State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Suzhou, Jiangsu 215123 (China); Chen, Dongyun; Xu, Qingfeng [Collaborative Innovation Center of Suzhou Nano Science and Technology, College of Chemistry, Chemical Engineering and Materials Science, Suzhou University, Suzhou, Jiangsu 215123 (China); State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Suzhou, Jiangsu 215123 (China); Lu, Jianmei, E-mail: lujm@suda.edu.cn [Collaborative Innovation Center of Suzhou Nano Science and Technology, College of Chemistry, Chemical Engineering and Materials Science, Suzhou University, Suzhou, Jiangsu 215123 (China); State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Suzhou, Jiangsu 215123 (China)

    2017-05-01

    Highlights: • A recyclable photocatalyst was facilely fabricated by immobilization and grafting. • Contribution from each component in the composite towards enhanced performance. • High removal efficiency was achieved under adsorption-combined degradation. • The composite photocatalyst can be easily separated from water for direct reuse. - Abstract: A recyclable photocatalyst with adsorption property was prepared for high-efficient complete removal of anionic dyes from water by synergetic adsorption and photocatalytic degradation. Firstly, binary bismuth oxyhalide composed as BiOI{sub 0.5}Cl{sub 0.5} was immobilized on activated carbon fibers (ACF) to get a recyclable photocatalyst (ACF@BiOI{sub 0.5}Cl{sub 0.5}) via one-step solvothermal method. Then it was modified with branched polyethylene imine (PEI) whose abundant amino groups can adsorb contaminants from water by electrostatic interaction. SEM images showed that the nanosheets-based flower-like photocatalytic microspheres uniformly distributed on the ACF surface after grafting of small amount of PEI. But from TGA results we can deduce that the percentage of PEI grafted onto ACF@BiOI{sub 0.5}Cl{sub 0.5} is about 18 wt%. During the synergistic process, the grafted PEI and immobilized BiOI{sub 0.5}Cl{sub 0.5} are worked as the adsorbent and the photocatalyst, respectively. In addition, ACF, as flexible, conductive and corrosion-resistant supports, are beneficial to the photocatalytic degradation process. So the obtained composite PEI-g-ACF@BiOI{sub 0.5}Cl{sub 0.5} has a high removal efficiency of contaminants under visible light irradiation with the synergistic effect of adsorption and photocatalytic degradation. And after facial separation without centrifuge, it can be reused without regeneration because of the real-time complete degradation of the adsorbed contaminants on the surface of the composite photocatalyst.

  19. Comparative study of phase structure and dielectric properties for K0.5Bi0.5TiO3-BiAlO3 and LaAlO3-BiAlO3

    International Nuclear Information System (INIS)

    Hou, Yudong; Zheng, Mupeng; Si, Meiju; Cui, Lei; Zhu, Mankang; Yan, Hui

    2013-01-01

    In this work, two perovskite-type compounds, K 0.5 Bi 0.5 TiO 3 and LaAlO 3 , have been selected as host material to incorporate with BiAlO 3 using a solid-state reaction route. The phase evolution and dielectric properties for both systems have been investigated in detail. For the K 0.5 Bi 0.5 TiO 3 -BiAlO 3 system, it is interesting to find that when using Bi 2 O 3 , Al 2 O 3 , K 2 CO 3 , and TiO 2 as starting materials, the formed compounds are K 0.5 Bi 0.5 TiO 3 -K 0.5 Bi 4.5 Ti 4 O 15 and Al 2 O 3 only plays a dopant role. There are two distinct dielectric peaks appearing in the patterns of temperature dependence of dielectric constant, corresponding to the phase-transition points of perovskite-type K 0.5 Bi 0.5 TiO 3 and Aurivillius-type K 0.5 Bi 4.5 Ti 4 O 15 , independently. In comparison, using Bi 2 O 3 , Al 2 O 3 , and La 2 O 3 as starting materials, the pure perovskite phase LaAlO 3 -BiAlO 3 can be obtained. Compared to the inherent paraelectric behavior in LaAlO 3 , the diffuse phase-transition phenomena can be observed in the LaAlO 3 -BiAlO 3 binary system, which corresponds well to the Vogel-Fulcher (VF) relationship. Moreover, compared to pure LaAlO 3 , the synthesized LaAlO 3 -BiAlO 3 compound shows enhanced dielectric properties, which are promising in application as gate dielectric materials. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Alanine-EPR dosimetry for measurements of ionizing radiation absorbed doses in the range 0.5-10 kGy

    CERN Document Server

    Peimel-Stuglik, Z

    2001-01-01

    The usefulness of two, easy accessible alanine dosimeters (ALANPOL from IChTJ and foil dosimeter from Gamma Service, Radeberg, Germany) to radiation dose measurement in the range of 0.5-10 kGy, were investigated. In both cases, the result of the test was positive. The foil dosemeter from Gamma Service is recommended for dose distribution measurements in fantoms or products, ALANPOL - for routine measurements. The EPR-alanine method based on the described dosimeters can be successfully used, among others, in the technology of radiation protection of food.

  1. Bloqueio do plexo lombar pela via posterior para analgesia pós-operatória em artroplastia total do quadril: estudo comparativo entre Bupivacaína a 0,5% com Epinefrina e Ropivacaína a 0,5% Bloqueo del plexo lumbar por la vía posterior para analgesia postoperatoria en artroplastia total de la cadera: estudio comparativo entre Bupivacaína a 0,5% con Epinefrina y Ropivacaína a 0,5% Posterior lumbar plexus block in postoperative analgesia for total hip arthroplasty: a comparative study between 0.5% Bupivacaine with Epinephrine and 0.5% Ropivacaine

    Directory of Open Access Journals (Sweden)

    Leonardo Teixeira Domingues Duarte

    2009-06-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: O bloqueio do plexo lombar pela via posterior promove analgesia pós-operatória efetiva na artroplastia total do quadril. Ropivacaína e bupivacaína não apresentaram qualquer diferença na eficácia analgésica em diferentes bloqueios de nervos periféricos. O objetivo deste estudo foi comparar a eficácia da analgesia pós-operatória resultante da administração em dose única da bupivacaína a 0,5% ou da ropivacaína a 0,5% no bloqueio do plexo lombar pela via posterior na artroplastia total do quadril. MÉTODO: Trinta e sete pacientes foram alocados aleatoriamente em dois grupos, segundo o anestésico local utilizado no bloqueio: Grupo B - bupivacaína a 0,5% com epinefrina 1:200.000 ou Grupo R - ropivacaína a 0,5%. Durante o período pós-operatório, os escores de dor e o consumo de morfina na analgesia controlada pelo paciente foram comparados entre os grupos. O sangramento durante a operação e a incidência de efeitos adversos e de complicações também foram comparados. RESULTADOS: Apesar dos escores de dor terem sido menores no Grupo R 8, 12 e 24 horas após o bloqueio, essas diferenças não foram clinicamente significativas. Regressão linear múltipla não identificou o anestésico local como variável independente. Não houve diferença no consumo de morfina, no sangramento intraoperatório e na incidência de complicações e efeitos adversos entre os dois grupos. CONCLUSÕES: A bupivacaína a 0,5% e a ropivacaína a 0,5% produziram alívio eficaz e prolongado da dor pós-operatória após artroplastia total do quadril, sem diferença clínica, quando doses equivalentes foram administradas no bloqueio do plexo lombar pela via posterior.JUSTIFICATIVA Y OBJETIVOS: El bloqueo del plexo lumbar por la vía posterior, genera una analgesia postoperatoria efectiva en la artroplastia total de la cadera. La ropivacaína y la bupivacaína no arrojaron ninguna diferencia en la eficacia analgésica en

  2. Efficiency, safety, and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog.

    Science.gov (United States)

    Shimizu, Yoshie; Nakakura, Shunsuke; Nishiyama, Makiko; Tabuchi, Hitoshi; Kiuchi, Yoshiaki

    2015-01-01

    We investigated the efficiency, safety and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog. We initially enrolled 44 eyes from 44 primary open angle glaucoma patients, and a total of 42 patients completed the study. All patients were under treatment with various prostaglandin F2α analogs and dorzolamide 1%/timolol 0.5%. While maintaining the prostaglandin F2α analog, dorzolamide 1%/timolol 0.5% was switched to brinzolamide 1%/timolol 0.5%. Conjunctival hyperemia, superficial punctate keratopathy, and intraocular pressure (IOP) were evaluated at baseline and at 4, 12, and 24 weeks. Adverse events and patient preferences, measured using a questionnaire at study initiation and at 24 weeks, were also noted. The IOP was 17.7±1.7, 16.8±2.6, 16.7±2.2, and 16.7±2.4 mmHg at baseline and at 4, 12, and 24 weeks, respectively, with no significant differences in IOP values at any time point (P=0.117, one-way analysis of variance). In addition, no significant differences were found in the incidence of conjunctival hyperemia or SPK score at any time point (all P>0.5, by Kruskal-Wallis test). Based on the evaluation of side effects using the questionnaire, stinging/burning was less common (P=0.042), while blurred vision was more common (P=0.003), after switching to brinzolamide 1%/timolol 0.5%. Regarding patient preferences, 13 patients (31%) preferred dorzolamide 1%/timolol 0.5%, 12 patients (29%) preferred brinzolamide 1%/timolol 0.5%, and 17 patients (40%) preferred neither. When switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5%, the IOP values and incidence of superficial punctate keratopathy and conjunctival hyperemia were sustained throughout the 24-week observation period, and the patient preferences were similar for the two regimens. However, differences were observed in the ocular sensations of stinging/burning with dorzolamide 1%/timolol 0.5

  3. Efficiency, safety, and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog

    Directory of Open Access Journals (Sweden)

    Shimizu Y

    2015-03-01

    Full Text Available Yoshie Shimizu,1 Shunsuke Nakakura,1 Makiko Nishiyama,1 Hitoshi Tabuchi,1 Yoshiaki Kiuchi2 1Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, 2Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan Background: We investigated the efficiency, safety and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog.Methods: We initially enrolled 44 eyes from 44 primary open angle glaucoma patients, and a total of 42 patients completed the study. All patients were under treatment with various prostaglandin F2α analogs and dorzolamide 1%/timolol 0.5%. While maintaining the prostaglandin F2α analog, dorzolamide 1%/timolol 0.5% was switched to brinzolamide 1%/timolol 0.5%. Conjunctival hyperemia, superficial punctate keratopathy, and intraocular pressure (IOP were evaluated at baseline and at 4, 12, and 24 weeks. Adverse events and patient preferences, measured using a questionnaire at study initiation and at 24 weeks, were also noted.Results: The IOP was 17.7±1.7, 16.8±2.6, 16.7±2.2, and 16.7±2.4 mmHg at baseline and at 4, 12, and 24 weeks, respectively, with no significant differences in IOP values at any time point (P=0.117, one-way analysis of variance. In addition, no significant differences were found in the incidence of conjunctival hyperemia or SPK score at any time point (all P>0.5, by Kruskal–Wallis test. Based on the evaluation of side effects using the questionnaire, stinging/burning was less common (P=0.042, while blurred vision was more common (P=0.003, after switching to brinzolamide 1%/timolol 0.5%. Regarding patient preferences, 13 patients (31% preferred dorzolamide 1%/timolol 0.5%, 12 patients (29% preferred brinzolamide 1%/timolol 0.5%, and 17 patients (40% preferred neither.Conclusion: When switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1

  4. LIS/OTD 0.5 DEGREE HIGH RESOLUTION ANNUAL CLIMATOLOGY (HRAC) V2.3.2013

    Data.gov (United States)

    National Aeronautics and Space Administration — The product is a 0.5 deg x 0.5 deg gridded composite of total (IC+CG) lightning bulk production, expressed as a flash density (fl/km2/yr). Climatologies from the OTD...

  5. ASUPAN ZAT GIZI MAKRO DAN SERAT MENURUT STATUS GIZI ANAK USIA 6-12 TAHUN DI PULAU SULAWESI

    Directory of Open Access Journals (Sweden)

    Wulan Agustina

    2015-05-01

    Full Text Available ABSTRACTThe aimed of this study was to determine the differences intake of macro-nutrients (protein, fat, carbohydrates and fiber with respect to their nutritional status of children aged 6-12 years. This study was used secondary data Riskesdas 2010. The number of subjects was 2,987 children aged 6-12 years in Sulawesi Island. Body Mass Index for Age (BMI/U was used to measure the nutritional status. Independent sample t-test and analysis of variance were applied to answer the research questions. The result showed that most of subjects were male (58.7%, living in rural areas (50.2%, and with low economic status (54.1%. In regard to protein intake, most of the children age 6 years was about 80-99% Recommended Dietary Intake (RDA. On the contrary, most of children 7-9 years and 10-12 years were below 70% RDA. There were no differences intake of macro-nutrients (protein, fat, carbohydrates and fiber to the nutritional status of children aged 6-12 years (p>0.05. This study found that most of the children were suffering macro-nutrients intake regardless their nutritional status. Therefore, we need to have a good program to monitor nutritional status of school children.Keywords: nutrient intake, nutritional status, school age children 6-12 yearABSTRAKPenelitian ini bertujuan untuk mengetahui perbedaan asupan zat gizi makro (protein, lemak, karbohidrat dan serat terhadap status gizi pada anak usia 6-12 tahun. Penelitian ini menggunakan data sekunder Riskesdas 2010 dengan pendekatan cross-sectional. Subjek penelitian adalah anak usia 6-12 tahun dengan status gizi kurus, normal, dan gemuk menurut IMT/U di Pulau Sulawesi tahun 2010 berjumlah 2.087 orang. Pengujian statistik menggunakan independent sample t-test dan Anova. Sebagian besar subjek berjenis kelamin laki-laki (58,7%, tinggal di perdesaan (50,2%, dan berstatus ekonomi rendah (54,1%. Rata-rata asupan protein pada kelompok umur 6 tahun termasuk kategori sedang (80-99% AKG namun pada usia 7-9 tahun

  6. Metallic 1T-LixMoS2 Cocatalyst Significantly Enhanced the Photocatalytic H2 Evolution over Cd0.5Zn0.5S Nanocrystals under Visible Light Irradiation.

    Science.gov (United States)

    Du, Hong; Guo, Hong-Li; Liu, Ya-Nan; Xie, Xiao; Liang, Kuang; Zhou, Xiao; Wang, Xin; Xu, An-Wu

    2016-02-17

    In the present work, metallic 1T-LixMoS2 is utilized as a novel cocatalyst for Cd0.5Zn0.5S photocatalyst. The obtained LixMoS2/Cd0.5Zn0.5S hybrids show excellent photocatalytic performance for H2 generation from aqueous solution containing Na2S and Na2SO3 under splitting visible light illumination (λ ≥ 420 nm) without precious metal cocatalysts. It turns out that a certain amount of intercalating Li(+) ions ultimately drives the transition of MoS2 crystal from semiconductor triagonal phase (2H phase) to metallic phase (1T phase). The distinct properties of 1T-LixMoS2 promote the efficient separation of photoexcited electrons and holes when used as cocatalyst for Cd0.5Zn0.5S photocatalyst. As compared to 2H-MoS2 nanosheets only having edge active sites, photoinduced electrons not only transfer to the edge sites of 1T-LixMoS2, but also to the plane active sites of 1T-LixMoS2 nanosheets. The content of LixMoS2 in hybrid photocatalysts influences the photocatalytic activity. The optimal 1T-LixMoS2 (1.0 wt %)/Cd0.5Zn0.5S nanojunctions display the best activity for hydrogen production, achieving a hydrogen evolution rate of 769.9 μmol h(-1), with no use of noble metal loading, which is about 3.5 times higher than that of sole Cd0.5Zn0.5S, and 2 times higher than that of 2H-MoS2 (1.0 wt %)/Cd0.5Zn0.5S samples. Our results demonstrate that Li(+)-intercalated MoS2 nanosheets with high conductivity, high densities of active sites, low cost, and environmental friendliness are a prominent H2 evolution cocatalyst that might substitute for noble metal for potential hydrogen energy applications.

  7. Effect of dynamic crosslinking on phase morphology and mechanical properties of polyamide 6,12/ethylene vinyl acetate copolymer blends

    Directory of Open Access Journals (Sweden)

    Fabrício Bondan

    2015-03-01

    Full Text Available The dynamic crosslinking of polyamide 6,12 and ethylene vinyl acetate (PA6,12/EVA blends in the mixing chamber of a torque rheometer was investigated. EVA was selectively crosslinked within the PA6,12 phase through free radical reactions using dycumil peroxide. The degree of EVA crosslinking in the PA12,6/EVA materials was estimated based on the gel content (insoluble EVA fraction. The PA6,12/EVA phase morphology was investigated by scanning electron microscopy. The mechanical properties were investigated by determining the tensile strength and hardness. The half-life time ( for homolytic scission of the dcumil peroxide (DCP was ~6s, and this time is longer than the dispersion time of the DCP in the blends. The addition of DCP resulted in increased torque values due to specific crosslinking in the EVA phase. For the pure EVA and its blends with PA6,12 the stabilized torque values increased proportionally with the amount of DCP in the system, due to a higher degree of crosslinking of the elastomeric phase. The gel content of the dynamically crosslinked blends increased with the amount of DCP incorporated until 4 phr. At 1 phr the gel content value was 2.6wt.%, while at 4 phr it was 17wt.%. For the polymer blend with 8 phr of DCP a lubricating effect contributed to reducing the gel content. The dynamically crosslinked blends, regardless of the amount of DCP added, showed a reduction in the mechanical properties, which is related to the morphological features of the system due to the low mechanical fragmentation during melt processing.

  8. Ultrasonographic findings of papillary carcinoma of the thyroid according to the size: Especially less than 0.5 cm

    Energy Technology Data Exchange (ETDEWEB)

    Park, So Yung; Kim, Yun Min; Lee, Hyun Bok; Cho, Nam Soo [Dept. of Diagonostic Radiology, Samsung Medical Center, Seoul (Korea, Republic of); Yoon, Joon [Dept. of Radiologic Technology, Dongnam Health College, (Korea, Republic of)

    2013-06-15

    The Korean Thyroid Association recommends fine-needle aspiration biopsy (FNAB) for nodules more than 0.5 cm in diameter. But nodules, smaller than 0.5 cm have been found in papillary carcinomas of the thyroid (PTC) at the health promotion center at SMC. We wanted to evaluate the ultrasonographic findings according to size of nodule in proven PTCs by FNAB, especially less than 0.5 cm. All nodules were classified into three groups by their longest diameter : less than 0.5 cm, more than 0.5 cm but less than 1 cm, and more than 1 cm. Sonographic findings suggesting malignancy were analyzed according to their size groups. Of 288 malignant nodules, 21.5 % (62/288) were less than 0.5 cm , 54.9 % (158/288) were more than 0.5 cm but less than 1 cm, 23.6 % (68/288) exceeded 1 cm. A taller-than-wide shape was observed in 90.3 % (56/62) of nodules less than 0.5 cm, and 48.5 % (33/68) of nodules exceeding 1 cm (p<0.001). There were no well-defined smooth nodules among nodules less than 0.5 cm, and spiculated or irregular margin nodules increased as the size increased (p=0.024). Nodules of size less than 0.5 cm did not showed hyper or isoechogenicity. Hypoechogenicity was greater than the marked hypoechogenicity in each group (p=0.034). Micro- or macro-calcifications were not founded in 77.4 % (48/62) of the nodule group sized less than 0.5 cm. From the small size of the group, micro- or macrocalcifications were observed 21.0 % (13/62), 48.1 % (76/158), 64.7 % (44/68), so the number of nodules containing micro- or macro-calcification increased as size increased (p<0.001). PTCs less than 0.5 cm in size on ultrasonography had taller than-wide shape, spiculated or irregular and ill-defined margins, and exhibited hypo and markedly hypoechogenicity, but microor macro-calcifications were not common. These ultrasonographic features of nodules less than 0.5 cm can be useful in reporting and guiding FNABs or follow-up exams.

  9. Perceptions of society for vascular surgery members and surgery department chairs of the integrated 0 + 5 vascular surgery training paradigm.

    Science.gov (United States)

    Kiguchi, Misaki; Leake, Andrew; Switzer, Galen; Mitchell, Erica; Makaroun, Michel; Chaer, Rabih A

    2014-01-01

    As the first generation of integrated (0 + 5) vascular surgery (VS) residents enter the job market, this survey sought to understand how the surgical community perceives this training paradigm. An anonymous online survey was e-mailed to surgery chairpersons (n = 193) and Society for Vascular Surgery (SVS) members (n = 2193) in the United States/Canada with 26% (n = 38) and 14% (n = 309) response rates, respectively. Respondents were asked about their practice background, residency program, hiring patterns, and perceptions of the 0 + 5 training. Response rates were 26% (n = 38) and 14% (n = 309) for surgery chairpersons and SVS members, respectively. SVS respondents were from academic (62%) and private (38%) practices and included staff surgeons (62%), program directors (15%), and division chiefs (22%). Only 33% had a 0 + 5 program, and 57% had a VS fellowship. Overall, 94% were likely to hire a new vascular surgeon in the next 5 years. In some categories, SVS respondents believed 0 + 5 residents would be less prepared than 5 + 2 residents. Only 32% thought that 0 + 5 residents have the same level of surgical maturity, and 36% thought that they have the same level of open operative skills as 5 + 2 trainees. Another 34% thought 0 + 5 residents will need additional fellowship training in open surgery. However, there was also a general perception from SVS respondents that 0 + 5 residents would be prepared for clinical practice (67%) and would have equal endovascular skills to 5 + 2 trainees (92%). The chairpersons had similar perceptions as SVS members. Both SVS members (88%) and chairpersons (86%) would consider interviewing a 0 + 5 graduate for faculty position; 83% and 72%, respectively, would consider hiring. Moreover, 93% of SVS respondents who currently have a 0 + 5 program and 86% of SVS respondents who do not would consider hiring a 0 + 5 graduate. Both SVS members (62%) and chairpersons (50%) believed the 0 + 5 paradigm is essential for the advancement of VS

  10. The analysis of strain of giant magnetoresistive Pr0.7Sr0.3MnO3/La0.5Ca0.5MnO3/Pr0.7Sr0.3MnO-3 trilayers

    International Nuclear Information System (INIS)

    Wang Haiou; Liu Hao; Dai Ping; Tan Weishi; Wu Xiaoshan; Jia Quanjie; Li Xiaolong

    2012-01-01

    Pr 0.7 Sr 0.3 MnO 3 /La 0.5 Ca 0.5 MnO 3 /Pr 0.7 Sr 0.3 MnO 3 (PSMO/LCMO/PSMO) trilayers were deposited on (001)-oriented single crystal MgO by pulsed laser deposition. The thickness of both PSMO layers was 36 nm while the thickness of LCMO layer was 6, 12, 18, 24, 30 and 36 nm, respectively. Out-of-plane and in-plane lattice parameters of trilayers were obtained by using symmetric scanning and asymmetric scanning mode of high resolution X-ray diffraction. Strain states of trilayers have been studied. The results showed that strain relaxation states of trilayers were decided by bulk strain and Jahn-Teller (JT) strain together: The mechanism for strain relaxation in trilayers is different from that for tetragonal distortion. The competition between bulk strain and Jahn-Teller (JT) strain played an important role in the magnetotransport and magnetic properties of trilayers. (authors)

  11. Polyphosphoric acid supported on Ni0.5Zn0.5Fe2O4 nanoparticles as a magnetically-recoverable green catalyst for the synthesis of pyranopyrazoles

    Directory of Open Access Journals (Sweden)

    Farid Moeinpour

    2017-05-01

    Full Text Available Polyphosphoric acid supported on silica coated Ni0.5Zn0.5Fe2O4 nanoparticles was found to be magnetically separable, highly efficient, eco-friendly, green and recyclable heterogeneous catalyst. This new catalyst at first was fully characterized by TEM, SEM, FTIR and XRD techniques and then catalytic activity of this catalyst was investigated in the synthesis of 5-cyano-1,4-dihydropyrano[2,3-c]pyrazoles. Also the Ni0.5Zn0.5Fe2O4 magnetic nanoparticle-supported polyphosphoric acid could be reused at least six times without significant loss of activity. It could be recovered easily by applying an external magnet.

  12. Structural and Moessbauer Effect Studies of 0.5Bi0.95Dy0.05FeO3-0.5Pb(Fe2/3W1/3)O3 Multiferroic

    International Nuclear Information System (INIS)

    Stoch, A.; Zachariasz, P.; Stoch, P.; Kulawik, J.; Maurin, J.

    2011-01-01

    A polycrystalline ceramic of 0.5Bi 0.95 Dy 0.05 FeO 3 -0.5Pb(Fe 2/3 W 1/3 )O 3 was synthesized from a solid-state reaction method. At room temperature material exhibits both magnetic and electric dipolar properties simultaneously. Detailed X-ray diffraction analysis and Moessbauer effect studies have been done to determine the crystallographic structure and magnetic properties of 0.5Bi 0.95 Dy 0.05 FeO 3 -0.5Pb(Fe 2/3 W 1/3 )O 3 . T N temperature was estimated at around 600 K. (authors)

  13. Comparing the dynamic and thermodynamic behaviors of Al{sub 86}Ni{sub 9}-La{sub 5}/(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.H. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Wang, W.M. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: weiminw@sdu.edu.cn; Bian, X.F.; Zhang, J.T.; Li, R.; Wang, L. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-06-10

    The dynamic viscosities and thermodynamic dilatometric behaviors of Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys were investigated using viscometer, differential scanning calorimetry (DSC) and conventional dilatometer. Comparing with Al{sub 86}Ni{sub 9}La{sub 5} alloy, Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} alloy exhibits a larger viscosity and a larger average thermal expansion coefficient in the linear expansion zone ({alpha}{sub exp}). The viscosity and thermal expansion data suggest that the partial substitution La by Ce decreases the quantity of free volume in Al-Ni-La system by improving the continuous degree of atomic size, which leads to the improvement of glass forming ability.

  14. Influence of heat treatment on the mechanical and electrical characteristics of Ni{sub 0.5}Ti{sub 0.5} alloy prepared by electron-beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Ammar, A.H. [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University (Egypt); Physics Department, Faculty of Science and Arts, Al-Ola, Taibah University (Saudi Arabia); Al-Buhairi, M. [Physics Department, Faculty of Science, Taiz University (Yemen); Farag, A.A.M., E-mail: alaafaragg@yahoo.com [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University (Egypt); Al-Wajeeh, N.M.M. [Physics Department, Faculty of Science, Taiz University (Yemen)

    2013-06-15

    Nickel titanium alloys (Ni{sub 0.5}Ti{sub 0.5}) were successfully produced from elemental Ni/Ti powders by electron-beam melting method and then subjected to annealing and aging treatment. Microstructure of the alloys was examined by XRD and SEM. The mechanical properties of the alloyed surface were examined. The microhardness was studied as a function of annealing temperature and time. It was found that the microhardness decreases with increasing annealing temperature until 660 °C after which the microhardness increases. Electrical resistance measurements were carried out in order to study the transformation behavior. The electrical measurements point out the importance of temperature dependence of Ni{sub 0.5}Ti{sub 0.5} electrical resistance for the identification of particular transformation. The influence of aging on the development of electrical resistivity was also investigated.

  15. Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles with high intrinsic loss power for hyperthermia therapy

    Energy Technology Data Exchange (ETDEWEB)

    Phong, P.T., E-mail: phamthanhphong@tdt.edu.vn [Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Nam, P.H., E-mail: namph.ims@gmail.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Manh, D.H. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Lee, In-Ja, E-mail: lij@dongguk.ac.kr [Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, Dongdae-ro 123, Gyeongju-Si, Gyeongbuk 38066 (Korea, Republic of)

    2017-07-01

    Highlights: • Mn{sub 0.5}Zn{sub 0.5}FeO{sub 4} nanoparticles were synthesized using a hydrothermal method. • The coercivity at different temperatures was studied using the mixed coercivity model. • A superspin glass from strong interactions. • High intrinsic loss power was found to be comparable to that of ferrite and some commercial ferrofluids. - Abstract: Nanosized mixed ferrite Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} with crystalline size ∼15 nm has been prepared by hydrothermal route. XRD patterns confirm that the crystallites have single phase cubic spinel structure. The dynamic scaling analysis on the frequency dependence of spin glass-like transition temperature well explains the model of a transition at finite temperature. The analysis gives critical exponent and parameters as: zν = 10.48, T{sub 0} = 190 K, f{sub 0} = 5.38 × 10{sup 10} and this confirms the occurrence of spin glass-like transition in Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} particles. The saturation magnetization and the coercivity change with temperature. The effective magnetic anisotropy constant of sample was calculated using the law of approach to saturation. The coercivity at different temperatures was deduced using the mixed coercivity model. The calculated coercivity results are in a good agreement with the experimental ones. The magnetic heating ability of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} magnetic fluid was studied with an induction heating system. The calculated intrinsic loss power (ILP) was 3.75 g nHm{sup 2}/kg. This study indicates that the resulting Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles are promising materials in magnetic hyperthermia.

  16. Positive and negative exchange bias effects from magnetization reversal in Ho{sup 3+} doped YFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.R., E-mail: shiliran1127@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Wei, C.X.; Wang, Z.; Ju, L.; Xu, T.S.; Li, T.X.; Yan, X.W. [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Xia, Z.C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2017-07-01

    Highlights: • The dual magnetization reversal is observed in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. • The EB field transforms from negative to positive and then to negative. • A large exchange bias effect induced by Ho{sup 3+} doping is obtained in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. - Abstract: The polycrystalline ceramics of Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0, 0.05 and 0.1) are synthesized by a sol-gel method. The magnetization reversal and exchange bias effect are investigated in single phase bulk Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. Magnetic Ho{sup 3+} ion as a dopant is introduced into the system to confirm the influence of A-site ion on the magnetic interactions. The dual reversal of exchange bias field for x = 0.05 is observed, and its characteristic temperatures are corresponding to the compensation temperatures of magnetization reversal. The exchange bias field of x = 0.1 is found to be ∼10.03 kOe at 4 K, revealing a large value compared with that of x = 0. A schematic diagram based on the competition between the single ion anisotropy and Dzyaloshinsky-Moriya interaction, and the antiparallel coupling between the Ho{sup 3+} moments and the canted Cr{sup 3+}/Fe{sup 3+} moments, is used to understand the dual reversal phenomenon of magnetization and exchange bias effect.

  17. Effects of Rh on the thermoelectric performance of the p-type Zr0.5Hf0.5Co1-xRhxSb0.99Sn0.01 half-Heusler alloys

    International Nuclear Information System (INIS)

    Maji, Pramathesh; Takas, Nathan J.; Misra, Dinesh K.; Gabrisch, Heike; Stokes, Kevin; Poudeu, Pierre F.P.

    2010-01-01

    We show that Rh substitution at the Co site in Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 (0≤x≤1) half-Heusler alloys strongly reduces the thermal conductivity with a simultaneous, significant improvement of the power factor of the materials. Thermoelectric properties of hot-pressed pellets of several compositions with various Rh concentrations were investigated in the temperature range from 300 to 775 K. The Rh 'free' composition shows n-type conduction, while Rh substitution at the Co site drives the system to p-type semiconducting behavior. The lattice thermal conductivity of Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 alloys rapidly decreased with increasing Rh concentration and lattice thermal conductivity as low as 3.7 W/m*K was obtained at 300 K for Zr 0.5 Hf 0.5 RhSb 0.99 Sn 0.01 . The drastic reduction of the lattice thermal conductivity is attributed to mass fluctuation induced by the Rh substitution at the Co site, as well as enhanced phonon scattering at grain boundaries due to the small grain size of the synthesized materials. - Graphical abstract: Significant reduction of the lattice thermal conductivity with increasing Rh concentration in the p-type Zr 0.5 Hf 0.5 Co 1-x Rh x Sb 0.99 Sn 0.01 half-Heusler materials prepared by solid state reaction at 1173 K.

  18. 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.

  19. Efficiency, safety, and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog

    OpenAIRE

    Shimizu, Yoshie; Nakakura,Shunsuke; Nishiyama,Makiko; Tabuchi,Hitoshi; Kiuchi,Yoshiaki

    2015-01-01

    Yoshie Shimizu,1 Shunsuke Nakakura,1 Makiko Nishiyama,1 Hitoshi Tabuchi,1 Yoshiaki Kiuchi2 1Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, 2Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan Background: We investigated the efficiency, safety and patient preference of switching from dorzolamide 1%/timolol 0.5% to brinzolamide 1%/timolol 0.5% while maintaining the prostaglandin F2α analog...

  20. Ion mobility and conductivity in the M{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} (M=K, Rb) solid solutions with fluorite structure

    Energy Technology Data Exchange (ETDEWEB)

    Kavun, V. Ya., E-mail: kavun@ich.dvo.ru [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation); Uvarov, N.F. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, 18, Kutateladze Str., Novosibirsk 630128 (Russian Federation); Slobodyuk, A.B.; Polyantsev, M.M.; Merkulov, E.B. [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation); Ulihin, A.S. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, 18, Kutateladze Str., Novosibirsk 630128 (Russian Federation); Goncharuk, V.K. [Institute of Chemistry FEBRAS, 159, Pr. 100-letya Vladivostoka, Vladivostok 690022 (Russian Federation)

    2017-05-15

    Ionic mobility and conductivity in the K{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} and Rb{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} (x=0.05, 0.09) solid solutions with the fluorite structure have been investigated using the methods of {sup 19}F NMR, X-ray diffraction and impedance spectroscopy. Types of ionic motions in the fluoride sublattice of solid solutions have been established and temperature ranges of their realization have been determined (150–450 K). Diffusion of fluoride ions is a dominating type of ionic motions in the fluoride sublattice of solid solutions under study above 350 K. Due to high ionic conductivity, above 10{sup –3} S/cm at 450 K, these solid solutions can be used as solid electrolytes in various electrochemical devices and systems. - Graphical abstract: Temperature dependence of the concentration of mobile (2, 4) and immobile (1, 3) F ions in the K{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} solid solutions. - Highlights: • Studied the ion mobility, conductivity in M{sub 0.5–x}Pb{sub x}Bi{sub 0.5}F{sub 2+x} solid solutions (M=K, Rb). • An analysis of {sup 19}F NMR spectra made it possible to identify types of ion mobility. • The main type of ion motion above 300 K in solid solutions is a diffusion of ions F{sup –}. • The ionic conductivity of the solid solutions studied more than 10{sup –3} S/cm at 450 K.

  1. Effect of chitosan coating on the structural and magnetic properties of MnFe2O4 and Mn0.5Co0.5Fe2O4 nanoparticles

    Science.gov (United States)

    Mdlalose, W. B.; Mokhosi, S. R.; Dlamini, S.; Moyo, T.; Singh, M.

    2018-05-01

    We report the influence of polymer coatings on structural and magnetic properties of MnFe2O4 and Mn0.5Co0.5Fe2O4 nanoferrites synthesized by glycol thermal technique and then coated with chitosan viz. CHI-MnFe2O4 and CHI-Mn0.5Co0.5Fe2O4. The compounds were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), Mössbauer spectroscopy and magnetization measurements. The powder XRD patterns of naked nanoferrites confirmed single-phase spinel cubic structure with an average crystallite size of 13 nm, while the coated samples exhibited an average particle size of 15 nm. We observed a reduction in lattice parameters with coating. HRTEM results correlated well with XRD results. 57Fe Mössbauer spectra showed ordered magnetic spin states in both nanoferrites. This study shows that coatings have significant effects on the structural and magnetic properties of Mn-nanoferrites. Magnetization studies performed at room temperature in fields up to 14 kOe revealed the superparamagnetic nature of both naked and coated nanoparticles with spontaneous magnetizations at room temperature of 49.2 emu/g for MnFe2O4, 23.6 emu/g for coated CHI-MnFe2O4 nanoparticles, 63.2 emu/g for Mn0.5Co0.5Fe2O4 and 33.2 emu/g for coated CHI-Mn0.5Co0.5Fe2O4 nanoparticles. We observed reduction in coercive fields due to coating. Overall, chitosan-coated manganese and manganese-cobalt nanoferrites present as suitable candidates for biomedical applications owing to physicochemical, and magnetic properties exhibited.

  2. Oxygen isotope effect and phase separation in the optical conductivity of (La0.5Pr0.5)(0.7)Ca0.3MnO3 thin films

    NARCIS (Netherlands)

    Mena, FP; Kuzmenko, AB; Hadipour, A; van Mechelen, JLM; van der Marel, D; Babushkina, NA

    2005-01-01

    The optical conductivities of films of (La0.5Pr0.5)(0.7)Ca0.3MnO3 with different oxygen isotopes (O-16 and O-18) have been determined in the spectral range from 0.3 to 4.3 eV using a combination of transmission in the midinfrared and ellipsometry from the near-infrared to ultraviolet regions. We

  3. A comparative study of the magnetic properties and phase separation behavior of the rare earth cobaltates, Ln 0.5Sr0.5CoO3 (Ln=rare earth)

    International Nuclear Information System (INIS)

    Kundu, Asish; Sarkar, R.; Pahari, B.; Ghoshray, A.; Rao, C.N.R.

    2007-01-01

    A comparative study of the magnetic properties of a few members of the Ln 0.5 Sr 0.5 CoO 3 family with different radii of the A-site cations, A >, in the range 1.19-1.40 A has been carried out. The apparent T c (where the magnetization undergoes an abrupt increase) decreases markedly with A > as well as the size-disorder arising from the mismatch in the size of the A-site cations. The value of the magnetization at low temperatures decreases markedly with decrease in A > or increase in size-disorder, suggesting that the relative proportion of the ferromagnetic (FM) species decreases relative to that of the paramagnetic (PM) species. Such a variation of the FM/PM ratio with composition and temperature is evidenced from the Moessbauer spectra of La 0.5 Sr 0.5 CoO 3 as well. The variation of the FM/PM ratio with A > and size-disorder, as well as a local-probe study using 59 Co Nuclear magnetic resonance spectroscopy suggest that electronic phase separation is an inherent feature of the Ln 0.5 Sr 0.5 CoO 3 type cobaltates, with the nature of the different magnetic species in the phase-separated system varying with A > and size disorder. - Graphical abstract: Variation of (a) T c and (b) FC magnetization at 1000 Oe with A > at 120 K in Ln 0.5 Sr 0.5 CoO 3 and Dy 0.34 Nd 0.16 Sr 0.40 Ca 0.10 CoO 3

  4. Temperature-induced spin reorientation and magnetization jump of rare-earth orthoferrite Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohua; Zhao, Weiyao; Cao, Yiming; Kang, Baojuan [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Zhang, Jincang [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China); Ren, Wei, E-mail: renwei@shu.edu.cn [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China); Cao, Shixun, E-mail: sxcao@shu.edu.cn [Department of Physics, and International Center of Quantum and Molecular Structures, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai 200444 (China)

    2016-07-25

    We report temperature-induced spin reorientation and magnetization jump effects in the rare earth (RE) orthoferrite Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal. The single crystal of about 6 mm in diameter and 50 mm in length was successfully grown by optical floating zone method. Both X-ray diffraction and Laue photograph confirmed the homogeneity and high quality of the crystal. Magnetic properties of Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal are studied over a wide temperature range from 2 to 300 K. Spin reorientation transition from Γ{sub 2} to Γ{sub 4} phase is observed in the temperature range of 75–90 K. At lower temperature, the Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} shows an abrupt jump of magnetization along the a-axis, which occurs only in the field-cooling process, and is sensitive to external applied magnetic field. By analyzing the jump temperature and magnitude of the magnetization, we conclude that it is caused by the spin reversal of the rare earth ions. The isothermal magnetization versus field hysteresis loop measurements along a axis explain the spin configuration variation from 3 K to 60 K. - Highlights: • Ho{sub 0.5}Pr{sub 0.5}FeO{sub 3} single crystal was grown by optical floating zone method. • It shows an abrupt jump of magnetization along a axis at low temperature. • The jump height and temperature is sensitive to external applied magnetic field. • It is attributed to the spin reversal of the rare earth ions.

  5. High-pressure synthesis and magnetic behavior of A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Shimura, Gen; Niwa, Ken; Shirako, Yuichi; Hasegawa, Masashi [Department of Crystalline Materials Science, Nagoya University, 464-8601, Nagoya (Japan)

    2017-01-26

    A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd), were successfully synthesized under high pressure and high temperature (6 GPa, 1375 K). From the synchrotron powder X-ray diffraction patterns, all of the diffraction peaks can be indexed by the P4{sub 2}/nmc space group with lattice parameters a, c ∼ 2a{sub p} (a{sub p}: primitive cubic perovskite lattice) and no ordering of the B-site cations. Rietveld analysis of the synchrotron powder X-ray diffraction patterns and Curie-Weiss fitting of their magnetizations reveal that the ionic formulae of these perovskites are Ln{sup 3+}Mn{sup 2+}(Ga{sup 3+}{sub 0.5}Ti{sup 4+}{sub 0.5}){sub 2}O{sup 2-}{sub 6}. SmMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} shows canted-antiferromagnetic behavior, whereas GdMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve. These magnetic behaviors originate by decreasing the antiferromagnetic interaction by substituting Ga{sup 3+}(d{sup 10}) for Ti{sup 4+}(d{sup 0}) and by decreasing the ferromagnetic interaction between columnar-ordered Ln{sup 3+} and Mn{sup 2+}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. First-principles calculation of the effects of Li-doping on the structure and piezoelectricity of (K0.5Na0.5)NbO3 lead-free ceramics.

    Science.gov (United States)

    Yang, D; Wei, L L; Chao, X L; Yang, Z P; Zhou, X Y

    2016-03-21

    The crystal structures of the lead-free piezoelectric ceramics (K0.5Na0.5)NbO3 and (K0.5Na0.5)0.94Li0.06NbO3 prepared by a solid-state method were investigated using first-principles calculations. The calculated values of piezoelectricity were in good agreement with the experimental data. We found that the primary contribution to piezoelectricity in this material comes from the hybridization of the O 2p and Nb 4d orbitals, which causes a change in the Nb-O bond length and the distortion of the Nb-O octahedral structure. Analysis of the band structure and the total density of states revealed that Li-doped (K0.5Na0.5)NbO3 enhances hybridization of the O 2p and Nb 4d orbitals. This hybridization enhancement further reduces the Nb-O1 bond length and enhances the distortion of the Nb-O octahedron along the [001] direction, which may be the main reason for the improvement of the piezoelectric properties. In addition, the piezoelectric coefficients are calculated here, which show the same trend as the experimental results.

  7. Strain mediated magnetoelectric coupling induced in (x) Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x) MgFe{sub 2}O{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Manjusha [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); Adhlakha, Nidhi [Elettra-Sincrotrone Trieste S.C.p.A, Area Science Park, I-34012 Trieste (Italy); Shah, Jyoti; Kotnala, R.K. [CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2017-06-01

    Particulate composites of ferroelectric and ferrite phases having general formula (x)Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x)MgFe{sub 2}O{sub 4} (x=0, 0.5, 0.6, 0.7, 0.8 and 1.0), equivalently denoted as (x)BNT-(1−x)MgFO were synthesized by solid state reaction method. From X-ray diffraction analysis, the structural transformation from tetragonal to rhombohedral corresponding to BNT phase was observed in composites with x=0.5 to x=0.8. Shifting of (012) BNT peak towards left (x=0.5, 0.8) and right side (x=0.6, 0.7) observed due to occupation of Bi{sup 3+} ions at interstitial and substitutional sites into host MgFO lattice respectively. BNT produced strain in MgFO lattice. Scanning electron micrographs show closely packed microstructure with grain size variations from 0.62 to 2.90 µm. The value of magnetoelectric (ME) coupling coefficient increases from 2.42 (x=0.5) to 4.79 (x=0.8) mV/cm. Oe due to strain produced in MgFO and BNT lattices.

  8. Evidence of emerging Griffiths singularity in La{sub 0.5} Sr{sub 0.5} MnO{sub 3} nanocrystalline probed by magnetization and electron paramagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiyuan [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Fan, Jiyu, E-mail: jiyufan@nuaa.edu.cn [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Xu, Lisa [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Tong, Wei [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China); Hu, Dazhi [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); He, Xun [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Lei; Pi, Li; Zhang, Yuheng [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China)

    2016-06-01

    We present an investigation of Griffiths singularity in La{sub 0.5} Sr{sub 0.5} MnO{sub 3} nanocrystalline by means of magnetic susceptibility and electron paramagnetic resonance (EPR). An unusual platform was found in paramagnetic region. Based on the analysis of EPR spectrum and magnetization variation across the whole temperature range of phase transition, we confirm it is due to the presence of Griffiths singularity rather than a superparamagnetic state in the nanocrystalline system. Such a singularity phase is constituted with some correlated ferromagnetic clusters which embed in paramagnetic matrix. Although they form ferromagnetic spin correlation, the system do not yield any spontaneous magnetization. According to core–shell model, the emergence of Griffiths singularity can be considered due to the presence of local ferromagnetic fluctuations originated from surface spin disorder as the sample size is confined to nanoscale. - Highlights: • Griffiths singularity rather than superparamagnetism occurs in La{sub 0.5}Sr{sub 0.5}MnO{sub 3} nanoparticals. • The sample’s size reduced to nanoscale results in the short-range ferromagnetic interaction. • The core-shell model is used to understand the formation of Griffiths phase in nanometer La{sub 0.5}Sr{sub 0.5}MnO{sub 3}.

  9. Microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yih-Chien; Chen, Kuei-Chien; Hsu, Wei-Yu [Department of Electrical Engineering, Lunghwa University of Science and Technology, Gueishan Shiang, Taoyuan County (China)

    2010-11-15

    This study examined the potential applications of microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics in rectenna. The La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics were prepared by the conventional solid-state method with various sintering temperatures. An apparent density of 6.62 g/cm{sup 3}, a dielectric constant of 20.3, a quality factor of 51,700 GHz, and a temperature coefficient of resonant frequency of -78.2 ppm/K were obtained for La{sub 2.98/3}Ba{sub 0.01}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics that were sintered at 1550 C for 4 h. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Particle morphology and magnetic properties of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} powder calcined conventionally and by microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Kanagesan, S., E-mail: kanagu1980@gmail.com [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Hashim, M. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Jesurani, S. [Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625601, Tamil Nadu (India); Kalaivani, T. [Center for material science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Ismail, I.; Shafie, M.S.E. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Synthesis of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} by sol-gel technique. Black-Right-Pointing-Pointer Crystallization temperature is reduced to 900 Degree-Sign C due to the addition of D-Fructose. Black-Right-Pointing-Pointer Results of conventional and microwave calcined samples are reported. - Abstract: Barium strontium hexaferrite (Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}-BSF) has been prepared by sol-gel process involving use of D-Fructose as a fuel. The prepared precursor was calcined in two different calcinations techniques conventional and microwave furnace. X-ray powder diffraction studies confirmed the formation of single phase Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}. HR-SEM results show the morphology of the particles is hexagonal structures in platelet form. The average particle size of conventionally calcined BSF powder is 100-250 nm and that of microwave calcined powder is 30-100 nm. The broad hysteresis loop reveals that powder is well crystallized and exhibits hard magnetic properties.

  11. Dimensional t-factor variation and increase of stability of the ferroelectric state in (Na0.5Bi0.5TiO3-based solid solutions

    Directory of Open Access Journals (Sweden)

    V. M. Ishchuk

    2017-10-01

    Full Text Available The influence of the B-site ion substitutions in (1−x(Bi1∕2Na1∕2TiO3–xBaTiO3 system of solid solutions on the relative stability of the antiferroelectric (AFE and ferroelectric (FE phases has been studied. The ions of zirconium, tin, and (In0.5Nb0.5, (Fe0.5Nb0.5, (Al0.5V0.5 ion complexes have been used as substituting elements. An increase in the concentration of the substituting ion results in a near linear variation in the size of the crystal lattice cell. Along with the cell size variation, a change in the relative stability of the AFE and FE phases takes place according to the changes of the tolerance factor of the solid solution. An increase in the tolerance factor leads to the increase in the temperature of the FE–AFE phase transition, and vice versa. Obtained results indicate the way for raising the temperature of the FE–AFE phase transition in (Bi1∕2Na1∕2TiO3-based solid solutions.

  12. Anisotropic two-gap superconductivity and the absence of a Pauli paramagnetic limit in single-crystalline LaO0.5F0.5BiS2

    Science.gov (United States)

    Chan, Y. C.; Yip, K. Y.; Cheung, Y. W.; Chan, Y. T.; Niu, Q.; Kajitani, J.; Higashinaka, R.; Matsuda, T. D.; Yanase, Y.; Aoki, Y.; Lai, K. T.; Goh, Swee K.

    2018-03-01

    Ambient-pressure-grown LaO0.5F0.5BiS2 with a superconducting transition temperature Tc˜3 K possesses a highly anisotropic normal state. By a series of electrical resistivity measurements with a magnetic-field direction varying between the crystalline c axis and the a b plane, we present datasets displaying the temperature dependence of the out-of-plane upper critical field Hc2 ⊥(T ) , the in-plane upper critical field Hc2 ∥(T ) , as well as the angular dependence of Hc 2 at fixed temperatures for ambient-pressure-grown LaO0.5F0.5BiS2 single crystals. The anisotropy of the superconductivity, Hc2 ∥/Hc2 ⊥ , reaches ˜16 on approaching 0 K, but it decreases significantly near Tc. A pronounced upward curvature of Hc2 ∥(T ) is observed near Tc, which we analyze using a two-gap model. Moreover, Hc2 ∥(0 ) is found to exceed the Pauli paramagnetic limit, which can be understood by considering the strong spin-orbit coupling associated with Bi as well as the breaking of the local inversion symmetry at the electronically active BiS2 bilayers. Hence, LaO0.5F0.5BiS2 with a centrosymmetric lattice structure is a unique platform to explore the physics associated with local parity violation in the bulk crystal.

  13. Synthesis and characterization of SnO2, TiO2 and Ti0.5Sn0.5O2 nanoparticles as efficient materials for photocatalytic activity

    Science.gov (United States)

    Bargougui, R.; Pichavant, A.; Hochepied, J.-F.; Berger, M.-H.; Gadri, A.; Ammar, S.

    2016-08-01

    This work reports the synthesis of polydispersible SnO2, TiO2 and Ti0.5Sn0.5O2 nanoparticles via microwave-assisted polyol as an efficient method using diethylene glycol (DEG) and triethylene glycol (TREG) as solvent. The properties of as-prepared samples were investigated by X-ray diffractometry, transmission electron microscopy, diffuse reflectance and FTIR spectrophotometery, photoluminescence spectroscopy and N2 physisorption. The X-ray diffraction patterns of the samples were indexed on the anatase phase of TiO2 and cassiterite phase of SnO2 and Ti0.5Sn0.5O2. The TEM images show uniform isotropic morphologies with average sizes close to10 nm. The band gap is reduced for Ti0.5Sn0.5O2 and enhances visible light absorption, a shift resulting in the absorption threshold towards the visible spectral range, compared to pure titania and tin. Slight shifts to longer wavelength are attributed to the change in the acceptor's level induced by the mixture of both oxides. The evaluation of the photocatalytic activity is carried out using indigo carmine (IC) as model of chemical pollutants in UV irradiation conditions. The photocatalytic decolorization of the dye follows a pseudo-first-order kinetics and the constant apparent rate was increased with the increase of the tin oxide content up to 50%.

  14. Low temperature plasma-enhanced ALD TiN ultrathin films for Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric MIM structures

    Energy Technology Data Exchange (ETDEWEB)

    Kozodaev, M.G.; Chernikova, A.G.; Markeev, A.M. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); Lebedinskii, Y.Y. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoye Shosse 31, 115409 Moscow (Russian Federation); Polyakov, S.N. [Technological Institute for Superhard and Novel Carbon Materials, Tsentral' naya str. 7a, 142190, Troitsk, Moscow (Russian Federation)

    2017-06-15

    In this work chemical and electrical properties of TiN films, grown by low temperature plasma-enhanced atomic layer deposition (PE-ALD) process from TiCl{sub 4} and NH{sub 3}, were investigated. Electrical resistivity as low as 250 μOhm x cm, as well as the lowest Cl impurity content, was achieved at 320 C. Full-ALD Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based metal-ferroelectric-metal capacitor with TiN electrodes was fabricated and its electrical properties were investigated. It was also shown that the proposed PE-ALD process provides an early film continuity, which was confirmed by ultrathin fully continuous film growth. Such ultrathin (3 nm) and fully continuous TiN film was also successfully implemented as the top electrode to Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric capacitor. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was used for its thickness determination and a visible wake-up effect in underlying Hf{sub 0.5}Zr{sub 0.5}O{sub 2} layer was clearly observed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Comparative study of optical and scintillation properties of YVO{sub 4}, (Lu{sub 0.5}Y{sub 0.5})VO{sub 4}, and LuVO{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Yutaka, E-mail: fuji-you@tagen.tohoku.ac.j [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yanagida, Takayuki; Yokota, Yuui; Chani, Valery [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kochurikhin, Vladimir V. [General Physics Institute, 38 Vavilov Street, 119991, Federation, Moscow (Russian Federation); Yoshikawa, Akira [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); NICHe, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2011-04-11

    Optical and scintillation properties of YVO{sub 4}, (Lu{sub 0.5}Y{sub 0.5})VO{sub 4}, and LuVO{sub 4} single crystals grown by the Czochralski (CZ) method with RF heating system are compared. All vanadate crystals show high transmittance ({approx}80%) in the 400-900 nm wavelength range. In both photo- and radio-luminescence spectra, intense peak around 400-500 nm, which was ascribed to the transition from triplet state of VO{sub 4}{sup 3-}, was clearly observed. The main decay time component was about 38 {mu}s (YVO{sub 4}), 18 {mu}s ((Lu{sub 0.5}Y{sub 0.5})VO{sub 4}), and 17 {mu}s (LuVO{sub 4}) under 340 nm excitation. The scintillation light yields of YVO{sub 4}, (Lu{sub 0.5}Y{sub 0.5})VO{sub 4}, and LuVO{sub 4} crystals (obtained from the {sup 137}Cs excited pulse height spectra) were evaluated to be about 11,200, 10,700, and 10,300 ph/MeV, respectively.

  16. In vivo characterization of CYP2D6*12, *29 and *84 using dextromethorphan as a probe drug: a case report.

    Science.gov (United States)

    Gaedigk, Andrea; Twist, Greyson P; Farrow, Emily G; Lowry, Jennifer A; Soden, Sarah E; Miller, Neil A

    2017-04-01

    CYP2D6*84 was first described in a Black South African subject, however, its function remains unknown. Astrolabe, a probabilistic scoring tool developed in our laboratory to call genotypes from whole genome sequence, identified CYP2D6*84 in a trio. The father presented with intermediate metabolism when challenged with the CYP2D6 probe drug dextromethorphan (DM/dextrorphan [DX] = 0.0839). Since his second allele, CYP2D6*12, is nonfunctional, the observed activity is derived by CYP2D6*84. This finding suggests that the allele's hallmark P267H causes decreased activity toward DM and that this allele should receive a value of 0.5 for Activity Score calculations. The mother's DM/DX of 0.0543 was consistent with the decreased activity classification of CYP2D6*29. The child, a critically ill neonate, was not phenotyped, but predicted to be a normal metabolizer.

  17. Cobalt-free perovskite Pr_0_._5Sr_0_._5Fe_1_−_xCu_xO_3_−_δ (PSFC) as a cathode material for intermediate temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Moura, Caroline G.; Grilo, João Paulo de F.; Macedo, Daniel A.; Cesário, Moisés R.; Fagg, Duncan Paul; Nascimento, Rubens M.

    2016-01-01

    PSFC (Pr_0_._5Sr_0_._5Fe_1_−_xCu_xO_3_−_δ) is a new perovskite-type oxide that has gained considerable attention as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs), due to its high mixed ionic-electronic conductivity below 800 °C. In this work, PSFC (Pr_0_._5Sr_0_._5Fe_1_−_xCu_xO_3_−_δ, x = 0.2 and 0.4) powders were synthesized by the citrate method and structurally characterized by X-ray diffractometry. Screen-printed cathodes were sintered at 1050 °C and electrochemically characterized by impedance spectroscopy at 600–800 °C in pure oxygen. The area specific resistances (ASR) of the Pr_0_._5Sr_0_._5Fe_0_._8Cu_0_._2O_3_−_δ material are shown to be competitive with typical values reported for cobalt-based cathodes in the measured temperature range, while, importantly, offering a significantly lower activation energy, 0.62 eV. The thermal expansion coefficients of these Co-free cathodes are in the range of 13–15 × 10"−"6 °C"−"1, in a temperature range 200–650 °C, demonstrating a good thermal compatibility with gadolinia doped ceria (CGO) electrolytes. - Highlights: • Cobalt-free Pr_0_._5Sr_0_._5Fe_1_−_xCu_xO_3_−_δ (PSFC) cathodes successfully prepared by the citrate method. • PSFC cathodes are thermally compatible with CGO electrolytes. • Pr_0_._5Sr_0_._5Fe_0_._8Cu_0_._2O_3_−_δ presents competitive area specific resistances of low activation energy, 0.62 eV.

  18. Refinement in the structural and magnetic properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} and its application as laser micro-propellant using ablation confinement

    Energy Technology Data Exchange (ETDEWEB)

    Raza Ahmad, Muhammad, E-mail: mrazaahmad@gmail.com [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan); Jamil, Yasir, E-mail: yasirjamil@yahoo.com [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Tabasuum, Ayesha [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Hussain, Tousif [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan)

    2015-06-15

    The transition metal-substituted cobalt ferrite nanoparticles Co{sub 0.5}X{sub 0.5}Fe{sub 2}O{sub 4} (with X=Cu, Zn, Mn and Ni) exhibit a wide range of properties that result in their application in low loss magnetic core materials, vertical recording heads, antenna rods, memory elements, ferrofluids, biomedical applications, sensors and laser propulsion. Keeping in view its importance we investigated for the first time the structural and magnetic properties of the Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} samples that were subsequently subjected to thermal treatments for different time durations. The average crystallite sizes of the synthesized samples were found in the range of 24–46 nm. The values of the saturation magnetization and coercivity varied from 25.7 to 31.2 emu/g and 523.59 to 927.62 O{sub e}, respectively. The XRD patterns showed that increase in thermal treatment time resulted in the refinement of the structure whereas the SEM micrographs depicted a uniform particle size distribution of the synthesized material. We also explored the application of the synthesized material as a micro-thruster. It was found that the confinement of the laser induced plasma of Co{sub 0.5}×{sub 0.5}Fe{sub 2}O{sub 4} led to an increase in the value of coupling coefficient from the range of 5.747×10{sup −5}–7.0644×10{sup −5} N-s/J for unconfined to that of 1.41×10{sup −4}–2.68×10{sup −4}N-s/J for confined plasma corresponding to the Nd:YAG laser fluencies of 4×10{sup 9} J/m{sup 2}–6×10{sup 9} J/m{sup 2}. - Highlights: • Thermal treatment modifies the properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}. • Change in magnetic properties with increase in calcination time. • Confinement increases the laser propulsion parameters of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}.

  19. NOAA TIFF Graphic- 0.5m Backscatter Mosaic of St. Croix (Buck Island), US Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geotiff represents a 0.5 meter resolution backscatter mosaic of the north shore of Buck Island, St. Croix, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography...

  20. The effectiveness of 0.5–0.7% tetracycline gel to reduced subgingival plaque bacteria

    Directory of Open Access Journals (Sweden)

    Ernie Maduratna Setiawati

    2008-09-01

    Full Text Available Background: The tetracycline was an antimicrobial agent, that a broad spectrum. In addition to the antimicrobial effects, their efficacy was also anticollagenase and removal of the smear layer on the root surface. Purpose: The aim of the study was to evaluate effectiveness tetracycline gel 0.5–0.7% to reduction subgingival plaque bacteria. Method: A laboratory experimental study was conducted to investigate the effectiveness tetracycline gel 0.5–0.7%. Samples were divided into 5 groups with different concentration. The antimicrobial effect was performed using spectrophotometer. The statistical test was used One-Way ANOVA with significant difference 5% and subsequently Tukey-HSD test. Result: The study showed that tetracycline gel 0.5% has the highest antimicrobial has the highest antimicrobial effect. Conclusion: Tetracycline gel with 0.5% concentration is effective in inhibiting the growth of subgingival plaque bacteria.

  1. 78 FR 14095 - Determination That GEREF (Sermorelin Acetate) Injection, 0.5 Milligrams Base/Vial and 1.0...

    Science.gov (United States)

    2013-03-04

    ...] Determination That GEREF (Sermorelin Acetate) Injection, 0.5 Milligrams Base/Vial and 1.0 Milligrams Base/Vial, and GEREF (Sermorelin Acetate) Injection, 0.05 Milligrams Base/Amp, Were Not Withdrawn From Sale for...

  2. NOAA TIFF Graphic - 0.5 meter Backscatter Mosaic of St. John, U.S. Virgin Islands, 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This image represents a 0.5 meter resolution backscatter mosaic of the southern shore of St. John, US Virgin Islands.NOAA's NOS/NCCOS/CCMA Biogeography Team and...

  3. OMI/Aura Surface Reflectance Climatology Level 3 Global 0.5deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI Earth Surface Reflectance Climatology product, OMLER (Global 0.5deg Lat/Lon grid) which is based on Version 003 Level-1B top of atmosphere upwelling radiance...

  4. Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 3} ferrite synthesized by combustion and Pechini method for use in nanomedicine: methods evaluation; Ferrita Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 3} sintetizada por reacao de combustao e metodo Pechini para uso na nanomedicina: avaliacao dos metodos

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, I.L.T. de; Nascimento, A.L.C.; Costa, A.C.F.M., E-mail: allana.layla@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2016-07-01

    The objective of this work was to synthesize the Ni0.5Zn0.5Fe2O3 ferrite by combustion reaction and Pechini method, and to evaluate structural characteristics and magnetic behavior for its use in nanomedicine. The synthesized ferrite was characterized by DRX, BET, TG and magnetic properties. According to the results of XRD, the Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 3} ferrite synthesized by both methods presented nano crystallite sizes, high crystallinity, surface area, stable at high temperatures and with high saturation magnetization, being higher in the ferrite synthesized by combustion reaction. Both methods produced materials that could be used in nanomedicine.

  5. Modification of the ferrite load Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 3} by silane agent for improving the interface in the absorbing composite; Modificacao da carga de ferrita Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 3} por agente silano para melhoria da interface no composito absorvedor

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, P.C.F.; Santos, P.T.A.; Silva, T.R.G.; Costa, A.C.F.M.; Araujo, E.M., E-mail: patricia.fernandes24@hotmail.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    The main challenge of composite materials processing technology is the obtaining of an adequate interface between the components of a composite. Thus, this work aims to promote the modification of the ferrite load surface Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 3} (inorganic), by the silane agent (3-aminopropyltriethoxysilane) for introduction into the matrix of silicone (organic) rubber, and thus obtaining a efficient composite for use in electromagnetic radiation absorbing materials.

  6. XPS study of U, UNi5, UCu5 and UNisub(0.5)Cusub(4.5)

    International Nuclear Information System (INIS)

    Grohs, H.; Hoechst, H.; Steiner, P.; Huefner, S.; Buschow, K.H.J.

    1980-01-01

    Core and valence band spectra of U metal and the intermetallic compounds UNi 5 , UCu 5 and UNisub(0.5)Cusub(4.5) have been measured by X-ray excited photoelectron spectroscopy (XPS). The data indicate that in UNi 5 the configuration is 5f 3 , and in UCu 5 and UNisub(0.5)Cusub(4.5) a mixed valence configuration with fewer 5f electrons than in UNi 5 is present. (author)

  7. Core-shell Ni0.5TiOPO4/C composites as anode materials in Li ion batteries

    International Nuclear Information System (INIS)

    Zhang, X.J.; Zhang, Y.; Zhou, Z.; Wei, J.P.; Essehli, R.; Bali, B. El

    2011-01-01

    Pristine Ni 0.5 TiOPO 4 was prepared via a traditional solid-state reaction, and then Ni 0.5 TiOPO 4 /C composites with core-shell nanostructures were synthesized by hydrothermally treating Ni 0.5 TiOPO 4 in glucose solution. X-ray diffraction patterns indicate that Ni 0.5 TiOPO 4 /C crystallizes in monoclinic P2 1 /c space group. Scanning electron microscopy and transmission electron microscopy show that the small particles with different sizes are coated with uniform carbon film of ∼3 nm in thickness. Raman spectroscopy also confirms the presence of carbon in the composites. Ni 0.5 TiOPO 4 /C composites presented a capacity of 276 mAh g -1 after 30 cycles at the current density of 42.7 mA g -1 , much higher than that of pristine Ni 0.5 TiOPO 4 (155 mAh g -1 ). The improved electrochemical performances can be attributed to the existence of carbon shell.

  8. MR imaging of intracerebral hemorrhage lesions: Comparison of 2.0 T and 0.5 T images

    International Nuclear Information System (INIS)

    Han, Moon Hee; Chang, Kee Hyun

    1990-01-01

    Seventeen patients with intracerebral hemorrhage lesions were examined with magnetic resonance imaging at both 2.0 T and 0.5 T, in order to evaluate the capability of detecting and characterizing the hemorrhagic lesions at each field strength and to compare the signal intensities of the hemorrhages between both field strengths. The intervals between two imagings were within 2 hours in all patients except for 4 patients with subacute hematoma and occult cerebrovascular malformations in whom the intervals were 1 to 4 days. At each field strength, both T1 and T2-weighted spin echo(SE) images were obtained in all patients. All the hemorrhagic lesions were readily detected and characterized as hemorrhagic lesions at 2.0 T, whereas one lesion of chronic hemorrhage was not detected, and three lesions(one acute hemorrhage, one chronic hemorrhage and one occult cerebrovascular malformation) could not be characterized as hemorrhagic lesions at 0.5 T. There were statistically significant differences in signal intensity of the hematomas between 2.0 T and 0.5 T on proton density-weighted and T2-weighted images in cases of acute intracerebral hematomas: the hematomas seen as low intensity at 2.0 T appeared iso-or slightly high at 0.5 T. In conclusion, the intracerebral hematomas may be difficult to detect and to characterize with SE technique at 0.5 T, and then the gradient echo technique may be useful at 0.5 T

  9. Effect of sintering condition on the microstructure and electrical properties of lead-free (Na0.5K0.5NbO3 - Bi0.5(Na0.83K0.170.5TiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Wang Chun Huy

    2017-01-01

    Full Text Available In this work, the piezoelectric ceramic system of the (1-x(Na0.5K0.5NbO3 - xBi(Na0.83K0.17TiO3 with composition close to the morphotropic phase boundary is studied. (Na0.5K0.5NbO3 with 0∼5 mole% Bi(Na0.83K0.17TiO3 has been prepared following the conventional mixed oxide process. The effect of sintering time on the properties of 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 ceramics is discussed. For 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 ceramics, the electromechanical coupling coefficients of the thickness mode kt and the piezoelectric constant d33 reach 0.46 and 155 p/CN, respectively, at the sintering of 1100 °C for 3 h. Dielectric and piezoelectric properties have maximum values at the sintering temperature of 1100 °C for 5 h. For 0.97(Na0.5K0.5NbO3 -0.03Bi(Na0.83K0.17TiO3 ceramics, the electromechanical coupling coefficients of the thickness mode kt and the piezoelectric constant d33 reach 0.56 and 190, respectively, at the sintering of 1100 °C for 5 h. The effect of prolonging the sintering time to the 0.97(Na0.5K0.5NbO3-0.03Bi(Na0.83K0.17TiO3 system is a helpful method on ceramic processing to improve densification and properties.

  10. Flux synthesis, modulated crystal structures, and physical properties of REMn0.5SeO (RE = La, Ce)

    International Nuclear Information System (INIS)

    Peschke, Simon; Johrendt, Dirk; Nitsche, Fabian

    2015-01-01

    The selenide oxides REMn 0.5 SeO (RE = La, Ce) were synthesized by heating RE 2 O 3 , RE, Mn, and Se in a NaI/KI flux at 800 C, and their modulated crystal structures determined by X-ray single crystal and powder diffraction {P 1 1 2/n(αβ1/2)0s, Z = 2, LaMn 0.5 SeO: a = 405.7(1), b = 405.7(1), c = 915.2(1) pm, γ = 90 , q = [1/10, -1/10, 1/2]; CeMn 0.5 SeO: a = 402.0(1), b = 401.8(1), c = 910.7(1) pm, γ = 90.000(4) , q = [0.0789(2), -0.0783(2), 1/2]}. The structures are related to the ZrCuSiAs-type structure with ordered vacancies at the manganese sites. The resulting modulations of the checkerboard pattern in the [Mn 0.5 Se] layers can be approximated by 10a x 10b x 2c and 51a x 51b x 2c supercells in LaMn 0.5 SeO and CeMn 0.5 SeO, respectively. Both compounds are insulators. The optical bandgap of LaMn 0.5 SeO was determined to 2.13 eV from the Kubelka-Munk function. Magnetic measurements indicate antiferromagnetic ordering of the Mn 2+ moments with Neel points well above room temperature, as known from related manganese compounds. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Dielectric and impedance analysis of Li0.5La0.5Ti1-xZrxO3(x = 0.05 and 0.1 ceramics as improved electrolyte material for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Babu K. Vijaya

    2016-09-01

    Full Text Available The most attractive property of Li0.5La0.5TiO3 (LLTO electrolytes is their high ionic conductivity. Studies have shown that LLTO is capable of existing in a state with an ionic conductivity of 10-3 S/cm, which is comparable to liquid electrolytes. In addition to the high ionic conductivity of the material, LLTO is electrochemically stable and able to withstand hundreds of cycles. So, the studies of the solid electrolyte material are very important for the development of lithium-ion batteries. In the present paper, Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1 have been prepared by a solid-state reaction method at 1300 °C for 6 hours to improve electrolyte materials for lithium-ion batteries. The phase identified by X-ray diffractometry and crystal structure corresponds to pm3m (2 2 1 space group (Z = 1. The frequency and temperature dependence of impedance, dielectric permittivity, dielectric loss and electric modulus of the Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1 have been investigated. The dielectric and impedance properties have been studied over a range of frequency (42 Hz to 5 MHz and temperatures (30 °C to 100 °C. The frequency dependent plot of modulus shows that the conductivity relaxation is of non-Debye type.

  12. Effects of A-site nonstoichiometry on oxide ion conduction in 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Sasiporn Prasertpalichat

    2016-06-01

    Full Text Available Lead free 0.94(Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics were prepared by conventional solid-state mixed oxide route with the A-site stoichiometry modified to incorporate donor-doping (through Bi-excess and acceptor-doping (through Na-excess. Both stoichiometric and nonstoichiometric ceramics exhibited a single perovskite phase with pseudo-cubic symmetry. A significant improvement in the dielectric properties was observed in Bi-excess compositions and a deterioration in the dielectric properties was observed in Na-excess compositions. Impedance spectroscopy was utilized to analyze the effects of A-site nonstoichiometry on conduction mechanisms. Compositions with Bi-excess resulted in an electrically homogeneous microstructure with an increase in resistivity by ∼3–4 orders of magnitude and an associated activation energy of 1.57eV which was close to half of the optical bandgap. In contrast, an electrically heterogeneous microstructure was observed in both the stoichiometric and Na-excess compositions. In addition, the Na-excess compositions exhibited low resistivities (ρ∼103Ω-cm with characteristic peaks in the impedance data comparable to the recent observations of oxide ion conduction in (Bi0.5Na0.5TiO3. Long term annealing studies were also conducted at 800∘C to identify changes in crystal structure and electrical properties. The results of this study demonstrates that the dielectric and electrical properties of 0.94(Bi0.5Na0.5TiO3–0.06BaTiO3 ceramics are very sensitive to Bi/Na stoichiometry.

  13. Layered perovskite PrBa0.5Sr0.5CoCuO5+δ as a cathode for intermediate-temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    Wang, Biao; Long, Guohui; Ji, Yuan; Pang, Mingjun; Meng, Xiangwei

    2014-01-01

    Highlights: • A single-phase layered-perovskite PrBa 0.5 Sr 0.5 CoCuO 5+δ (PBSCCu) is prepared by the EDTA–citrate complexing method. • PBSCCu cathode has a good chemical compatible with GDC electrolyte. • Partial substitution of Cu for Co can efficiently lower the thermal expansion coefficient. • Performances of PrBa 0.5 Sr 0.5 CoCuO 5+δ cathode based on Gd 0.1 Ce 0.9 O 1.95 electrolyte is reported firstly. - Abstract: Layered perovskite PrBa 0.5 Sr 0.5 CoCuO 5+δ (PBSCCo) oxide is synthesized by EDTA–citrate complexing method and investigated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction results show that PBSCCo is chemical compatible with Gd 0.1 Ce 0.9 O 1.95 (GDC) electrolyte below 950 °C. The thermal expansion coefficient of PBSCCo is 17.58 × 10 −6 K −1 between 30 °C and 900 °C. The maximum electrical conductivity of PBSCCo is 483 S cm −1 at 325 °C. The polarization resistance of PBSCCo cathode on GDC electrolyte is as low as 0.06 Ω cm 2 at 800 °C. The maximum power density of the electrolyte-supported single cell with PBSCCo cathode achieves 521 mW cm −2 at 800 °C. Preliminary results indicate that PBSCCo is a potential cathode material for application in IT-SOFCs

  14. Structural and optical properties of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano ferrites: Effect of sintering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Prashant, E-mail: prashant007thakur@gmail.com; Sharma, Rohit; Sharma, Vineet, E-mail: vineet.sharma@juiit.ac.in; Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in

    2017-06-01

    Mn-Zn ferrites have shown various remarkable applications e.g. in magnetic amplifiers, power transformers and electromagnetic interference etc. due to their high initial permeability. Mn–Zn ferrite powder (Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) has been prepared by the co-precipitation method and subsequently sintered at three different temperatures i.e. 973 K, 1173 K, 1373 K. Optical properties have been correlated with the structural properties. For structural properties X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) have been employed. It has been observed that there is an increase in crystallite size with sintering from 973 K to 1373 K and FTIR confirms the formation of bond between metal ion and oxygen ion at the octahedral site and tetrahedral site. A red shift has been confirmed from UV–visible absorption spectra and photoluminescence spectra have been reported with an increase in sintering temperature. - Graphical abstract: Mn–Zn ferrite powder (Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}) has been prepared by the co-precipitation method and subsequently sintered at three different temperatures i.e. 973 K, 1173 K, 1373 K. A red shift has been confirmed from UV–visible absorption spectra and photoluminescence spectra have been reported with an increase in sintering temperature. - Highlights: • Nanoparticles of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} have been prepared by the co-precipitation method. • There is an increase in crystallite size with sintering from 973 K to 1373 K. • A red shift is found in UV–visible and PL spectra with an increase in sintering temperature.

  15. Tuning of cu doping on phase transition and high-field phase diagram of Nd{sub 0.5}Sr{sub 0.5}Mn{sub 1−x}Cu{sub x}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shang, C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Xia, Z.C., E-mail: xia9020@hust.edu.cn [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Wei, M.; Jin, Z.; Chen, B.R.; Shi, L.R. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ouyang, Z.W. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Huang, S.; Xiao, G.L. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-10-15

    Pulsed high magnetic fields up to 52 T have been used in the systematic investigation of the magnetic properties of manganites Nd{sub 0.5}Sr{sub 0.5}Mn{sub 1−x}Cu{sub x}O{sub 3} (0≤x≤0.15). The Cu-doping dependent first-order metamagnetic transitions are observed below the charge ordering temperature, which is ascribed to both Cu-doping and field-induced collapse of the charge ordering with antiferromagnetic phase. Based on the magnetization and electrical transport measurements, a three-dimensional phase diagram with coordinate axis of temperature, magnetic field, and doping level has been obtained, in which the critical fields of the metamagnetic transitions increase with the increase in Cu content and decrease with increasing temperature. The experimental results confirm that Mn-site substitution with Cu destroys the Mn{sup 3+}–O{sup 2−}–Mn{sup 4+} bridges and weakens the double exchange interaction between Mn{sup 3+} and Mn{sup 4+} ions, which shows an obvious tuning effect on the metamagnetic transition under the external magnetic field. - Highlights: • Tuning effect of Cu-doping on the properties of Nd{sub 0.5}Sr{sub 0.5}Mn{sub 1−x}Cu{sub x}O{sub 3} was studied. • First-order metamagnetic transition was observed under high magnetic fields. • A phase diagram with temperature, magnetic field and doping level was obtained. • Cu-doping weakens the ferromagnetic coupling in Nd{sub 0.5}Sr{sub 0.5}Mn{sub 1−x}Cu{sub x}O{sub 3}.

  16. Synthesis and luminescent properties of Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4}: A strong red-emitting phosphor for LED and FED applications

    Energy Technology Data Exchange (ETDEWEB)

    Du, Peng; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2016-11-15

    A series of Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4} phosphors were prepared by a typical sol–gel method. The as-prepared samples possessed a single tetragonal phase and consisted of closely-packed particles. Under the excitation of 395 nm, all the phosphors exhibited the characteristic emissions of Eu{sup 3+} ions corresponding to the {sup 5}D{sub 0}→ {sup 7}F{sub J} transitions. The photoluminescence (PL) emission intensities were enhanced with the increment of Eu{sup 3+} ion concentration and the optimum doping concentration was 0.25 mol. The energy transfer mechanism between the Eu{sup 3+} ions was dominated by dipole–dipole interaction and the critical distance was found to be 8.45 Å. Furthermore, the temperature-dependent PL emission spectra suggested that the obtained phosphors had good thermal stability (60.4% of the initial intensity at 150 °C). In addition, the color purity, chromatic and cathodoluminescence (CL) properties of the Na{sub 0.5}Gd{sub 0.5}MoO{sub 4}:0.25Eu{sup 3+} phosphor were also investigated. The results indicated that the Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4} phosphors with excellent PL and CL properties may have potential applications in white light-emitting diodes and field-emission displays.

  17. Investigation of structural and magnetic properties of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano powders prepared by self combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Sudheesh, V.D.; Nehra, J.; Vinesh, A. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Sebastian, V. [Department of Physics, Nirmalagiri College, Kuthuparamba 670701, Kerala (India); Lakshmi, N., E-mail: nambakkat@yahoo.com [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Dutta, Dimple P. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Reddy, V.R. [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001, M.P. (India); Venugopalan, K. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Gupta, Ajay [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001, M.P. (India)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} prepared by self combustion with uniform/nonuniform heating. ► Characterized using TEM, XRD, in-field Mössbauer and DC magnetometry. ► Leads to bimodal (S1) and very narrow size distribution (S2) type nano samples. ► S1 has magnetic properties of bulk Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. ► Although very even sized, S2 large magnetic anisotropy distribution. -- Abstract: Nano powders of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} have been synthesized by the self-combustion method at a relatively low temperature of 473 K under conditions of non-uniform and uniform heating. Rietveld fitting of X-ray diffractograms confirm the formation of the pure spinel phase in both samples. Transmission electron microscopy indicates that the sample prepared under non-uniform heating has a bimodal particle size distribution (average values 16 nm and 6 nm) while the one prepared under uniform heating has a very narrow particle size distribution (average size 4 nm). Low temperature, in-field Mössbauer spectroscopic studies clearly show surface spin contributions. The hyperfine fields and Curie temperature of the non-uniformly heated sample are in good agreement with those reported for the corresponding bulk samples. Despite having a very narrow particle size distribution, the uniformly heated sample has a large anisotropy distribution which is evident in the broad transition visible in the temperature dependent magnetization curve. It is also corroborated by the fact that the experimental magnetization curve at room temperature requires two Langevin functions for satisfactory reproduction.

  18. Design of Nickel-Based Cation-Disordered Rock-Salt Oxides: The Effect of Transition Metal (M = V, Ti, Zr) Substitution in LiNi0.5M0.5O2 Binary Systems.

    Science.gov (United States)

    Cambaz, Musa Ali; Vinayan, Bhaghavathi P; Euchner, Holger; Johnsen, Rune E; Guda, Alexander A; Mazilkin, Andrey; Rusalev, Yury V; Trigub, Alexander L; Gross, Axel; Fichtner, Maximilian

    2018-06-20

    Cation-disordered oxides have been ignored as positive electrode material for a long time due to structurally limited lithium insertion/extraction capabilities. In this work, a case study is carried out on nickel-based cation-disordered Fm3 ̅m LiNi 0.5 M 0.5 O 2 positive electrode materials. The present investigation targets tailoring the electrochemical properties for nickel-based cation-disordered rock-salt by electronic considerations. The compositional space for binary LiM +3 O 2 with metals active for +3/+4 redox couples is extended to ternary oxides with LiA 0.5 B 0.5 O 2 with A = Ni 2+ and B = Ti 4+ , Zr 4+ , and V +4 to assess the impact of the different transition metals in the isostructural oxides. The direct synthesis of various new unknown ternary nickel-based Fm3̅ m cation-disordered rock-salt positive electrode materials is presented with a particular focus on the LiNi 0.5 V 0.5 O 2 system. This positive electrode material for Li-ion batteries displays an average voltage of ∼2.55 V and a high discharge capacity of 264 mAhg -1 corresponding to 0.94 Li. For appropriate cutoff voltages, a long cycle life is achieved. The charge compensation mechanism is probed by XANES, confirming the reversible oxidation and reduction of V 4+ /V 5+ . The enhancement in the electrochemical performances within the presented compounds stresses the importance of mixed cation-disordered transition metal oxides with different electronic configuration.

  19. Orbital-Specific observation of O2p and Ni3d electrons in LiNi0.5Mn0.5O2, a cathode material for lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Yoshinori Satou

    2017-09-01

    Full Text Available Cathode materials for lithium-ion batteries containing Ni2+ have attracted much interest because of their high theoretical capac